The eye care practitioner is in a unique position to provide expert consultative services to athletes regarding vision correction and the potential uses and benefits of ophthalmic products. The practitioner should consider the nature of the athletic activity (contact vs. noncontact sports) as well as the weather and atmospheric conditions that may be encountered by the athlete. These aspects oblige the practitioner to consider and analyze the following environmental factors:
the presence of ocular hazards;
the need for protection from impact for the eye, face, and head;
the need for protection from solar radiation;
issues of visibility and mechanical forces with protection;
issues with sunlight conditions (variability and glare);
issues with artificial lighting (color perception and glare);
temperature issues that may affect ophthalmic products;
humidity conditions, especially low humidity with contact lens (CL) wear;
altitude factors that may affect oxygen transmission in CL wear;
dust and foreign body potential;
sweat, fogging, and precipitation effects with ophthalmic products;
the need for product flexibility because of environmental variability.
These environmental factors will be addressed in the following sections to assist the practitioner in determining the advantages and disadvantages of the available options. Each athlete has individual variables that affect ophthalmic recommendations. The gender, age, level of participation, combination of sports activities, and previous history of product use influence the choice of available options. Some athletes seek a single product to meet all visual performance needs, whereas others seek the optimal products for a variety of highly specific uses. Effective patient counseling begins with a thorough history to determine the specific needs and profile for the individual. Many patients would like to make informed decisions about the use of ophthalmic products; therefore a thorough case history coupled with comprehensive education and recommendations establish the practitioner as a valuable resource for the athlete.
Studies conducted on populations of teenaged and professional adult athletes have found similar incidence of refractive error and visual symptoms as in the general population (approximately 20%–40%), dispelling the impression that athletes have a lower incidence of refractive error and vision problems. Athletes who currently use vision correction require an evaluation to determine if the prescription is providing optimal visual performance for the specific sport demands. A task analysis of the sport will assist in determining the specific visual demands, and a careful refractive analysis can establish the best refractive compensation for use in that sport. For example, a myopic baseball player may benefit from an additional 0.25 D of minus to improve contrast judgment or when playing in twilight conditions. This prescription becomes the sport-specific prescription and is not intended for general use. Other sports, such as billiards, have specific viewing distances that should be considered, especially for the presbyopic athlete.
The eye care practitioner should advise athletic patients about the advantages and disadvantages of spectacles, protective eyewear, CLs, and refractive surgery for specific sports. The athlete should be able to make an informed decision about the best option for his or her individual needs. If spectacles are an option, the athlete should be counseled on the best lens characteristics, frame designs, tint characteristics, and protection factors. CLs offer a method to minimize many of the disadvantages found with most spectacle corrections, specifically poor optics, distortion, lack of safety, and lack of comfort. Refractive surgery offers the potential advantage of eliminating the need for optical devices; however, surgical procedures have safety and suboptimal vision performance outcome concerns. Orthokeratology offers an alternative to refractive surgery for some athletes.
For the approximately 80% of athletes who do not use vision correction, some may benefit from a sport-specific refractive prescription. To determine the possible benefits of a refractive prescription, the eye care provider should consider the athlete’s entering unaided visual acuities, the visual demands of the sport, and the effort exerted by the athlete to achieve clarity. For example, a golfer with unaided visual acuities of 20/25 (6/7.5) may appreciate the improved ability to judge the terrain of the course and find the ball when wearing a −0.25 DS prescription. This amount of myopia is typically insignificant, but the lack of compensation may have an impact on golf performance. Similarly, an uncorrected hyperope may find relief from eye strain with a prescription when playing tennis.
Guidelines have been published to assist the practitioner in determining when refractive compensation should be considered ( Table 6.1 ). Any patient with myopia of −0.25 D or more should be counseled on the possible benefits of refractive compensation. Astigmatism has a similar effect on visual resolution as myopia, especially against-the-rule and oblique astigmatism. Refractive compensation should be considered with −0.50 D or more astigmatism, although with-the-rule astigmatism compensation may not yield as much improvement on clinical measures. Low amounts of hyperopia are often well tolerated without correction; however, hyperopia of +1.00 D or greater may require a significant amount of effort from the athlete to achieve and maintain clarity. Low amounts of anisometropia are not always compensated for, especially when the refractive errors are low. Anisometropia of 0.50 D or more can have a detrimental effect on depth perception, and some athletes may be sensitive to that effect. Additionally, the effects of meridional anisometropia should be considered in athletes with asymmetric astigmatism. These guidelines are useful for the practitioner to trigger the discussion of the potential benefits of a refractive prescription; the athlete ultimately makes the decision whether to experiment with the prescription.
|Refractive Status||Consider Prescribing at|
|Myopia||−0.25 D or more|
|Hyperopia||+1.00 D or more|
|Astigmatism||0.50 D or more a|
|Anisometropia||0.50 D or more b|
a Against-the-rule astigmatism and oblique astigmatism are more detrimental than with-the-rule astigmatism.
When an athlete decides to experiment with a refractive prescription and he or she has not previously worn a correction, the timing of the experimentation should be discussed. The best time to experiment is during the off-season. The athlete is typically not competing at that time, so adaptation to the prescription will not directly affect critical performance. Athletes generally use the off-season to rest, work on biomechanical skills, and prepare their physical conditioning for the next season. This presents a perfect opportunity to experiment with refractive compensation. If a new prescription is introduced during the competitive season, the athlete may find that performance is negatively affected during the adaptation to the magnification effects induced by spectacle lens wear. For example, a basketball player who wears a myopic prescription for the first time will need to adjust to the change in spatial perception induced by the lenses (e.g., the basket can appear closer).
Presbyopia potentially presents a prescribing challenge in some sports activities. In many sports, a near addition is unnecessary because near visual acuity has a minimal impact on performance. In tennis, for example, clarity of near vision provides no advantage to performance. In golf, near visual acuity does not affect performance; however, clear near vision is desirable for seeing the score card and identifying the ball during play. A spectacle prescription with near addition lenses can interfere with the golfer’s view when addressing the ball and adjusting swing mechanics. A small, low-set segment set in one lens in the opposite viewing direction from the putting view angle has been recommended as a solution to this problem. For example, offset the segment in right gaze (lower temporal corner of the right lens) for a right-handed golfer. A better option may be CLs for playing the game and a near spectacle addition to use when scoring. Alternatively, a progressive addition lens (PAL) may be prescribed with a short corridor and narrow near zone set low to minimize peripheral distortion effects. For example, the Definity Fairway Transitions SOLFX and Oakley True Digital Golf PALs are designed for use in golf. Pilots and boat operators may require a double segment design, with positioning of the near additions to allow them to read instruments in downgaze and upgaze positions. Placing a small segment at the top of the lens and a traditional segment at the bottom of the lens typically provides a solution to the near-vision challenge (although this lens design is not currently available with polycarbonate lenses). Billiards players often use a single-vision intermediate-distance prescription during play, and the optical centers may need to be carefully measured in the billiards viewing position with strong prescriptions to minimize induced prism effects. Scuba divers may need a multifocal CL or spectacle prescription bonded to the face mask or attached as an insert within the mask to allow the diver to see the equipment, instruments, and underwater environment clearly. In these cases, a spectacle prescription must be adjusted for the significant increase in vertex distance created by the mask. For dynamic reactive sports, spectacle lenses produced better reaction times at near distances in presbyopes than CLs. Several companies offer PALs in high base (wrap) designs for use in sports.
The toughest challenge with presbyopia is created by shooters. Shotgun shooters are not significantly affected by the loss of accommodation because the task does not require critical alignment of sights on the target. Rifle shooting requires that the shooter clearly focus the target at a far distance while carefully aligning the front and rear sights of the rifle with the target. For the presbyope, the rifle’s front sight (intermediate distance) and rear sight (just beyond the spectacle plane) cannot be viewed with the same clarity as they were before the onset of presbyopia, and bifocal, trifocal, and multifocal lens designs do not offer an effective solution. Some shooters are happy with the distance correction slightly overplussed, creating a tolerable amount of blur for both the target and sights. Telescopic sights also have been recommended for this situation to allow clarity and accurate alignment without the need for near accommodation. Aiming scopes are available for archery as well; however, the increased magnification offered by these converging lenses does not improve visual acuity of the target because of the presence of significant dioptric blur. If spectacles are worn by the shooter, the lens material should protect the athlete and the eye relief distance should be sufficient to protect against rifle recoil. , As described with billiards, the optical centers may need to be carefully marked with the athlete in the shooting position(s) with a strong refractive prescription to minimize the induced prism effects.
Pistol shooters are particularly affected by presbyopia because the front and rear sights must be aligned with exacting precision as a result of the shorter length of the weapon. Again, the front sight is positioned at an intermediate distance from the eyes, and the difference in accommodative demand between the sights and the far target creates significant blur for one distance when focusing at the other. Presbyopic pistol shooters are particularly disturbed by the loss of image clarity and often want a solution that provides image clarity at both distances. A pinhole aperture can be created by punching a tiny hole in black electric tape and carefully aligning the tape on the spectacle lens of the aiming eye to allow adequate acuity at both distances for the early presbyope. As the pistol shooter approaches absolute presbyopia, the pinhole will no longer provide adequate relief and a bifocal spectacle will need to be carefully measured to allow clarity of the distant target through the upper lens and clarity of the pistol sights through the near addition lens. This movement between the distance correction and near correction should occur with 1 mm of head movement up or down when in the shooting position, and the practitioner should meticulously measure this position (with clear tape to simulate the add position) for a special-purpose shooting prescription. An executive or FT40 segment design will not induce a vertical image jump when moving into the near segment. A flip-down lens design that would allow clarity at two distances also has been recommended, , but the effect on alignment created by flipping the lenses may be unacceptable.
Nonprotective Sports Eyewear
A nonprotective spectacle correction is only recommended for use in some noncontact sports. In sports with a low incidence of contact (e.g., volleyball), other risks for eye injury exist, such as injury from the ball. In most sports the use of CLs or appropriate protective eyewear is preferred over the use of dress eyewear. Dress eyewear does not offer the impact resistance necessary to protect the wearer from the possible hazards encountered in many sports. There may be a need for education among non–eye care sports professionals regarding the advantages of CLs for use in sports.
The American National Standards Institute (ANSI) has established industry standards for the impact resistance of ophthalmic lenses. Dress eyewear performance standards are detailed in the ANSI Z80.1 standard, and the industrial strength (safety) eyewear standards are detailed in the ANSI Z87.1 standard. Outside the United States, there are regional (European Committee for Standardization) and global (International Organization for Standardization [ISO]) governing bodies that work cooperatively to develop eye protection standards. The use of polycarbonate, Trivex (PPG Industries, Pittsburgh, Pennsylvania), or NXT (Intercast Europe, Parma, Italy) lens materials can provide significantly improved impact attenuation properties over conventional glass and CR-39 lens materials. , Trivex and NXT materials deliver impact resistance similar to polycarbonate while also providing better optical clarity (higher Abbe value), lighter weight materials (lowest density), and improved scratch and crack/chip resistance. However, the frame construction of dress eyewear does not withstand the forces encountered in many sports. The ANSI Z80.3 standard for nonprescription sunglasses and dress eyewear and standards for sports protective eyewear are discussed later in this chapter.
Spectacle prescriptions are not commonly recommended for use in sports. The main concerns besides the lack of adequate eye protection provided by dress eyewear is the potential impact of optical aberrations of the lenses and visual field restriction created by the frames. Four of the seven monochromatic, or Seidel, lens aberrations can degrade the optical image transmitted through the off-center portions of the lens; radial or oblique astigmatism, power error caused by the curvature of the lens, lateral chromatic aberration, and distortion can each decrease the useful field of view through a lens. , The reduction in the useful field of view can have a detrimental impact on performance in sports. For example, a right-handed golfer viewing the hole during a putt looks through the left field portions of his or her spectacle lenses, and the image can be significantly altered in large refractive errors because of these aberrations. Stronger refractive prescriptions also produce larger amounts of prismatic effects when viewing away from the optical centers of the lenses, and the effect is increased with larger angles of view as approximated by Prentice’s rule. , Therefore lens design and optical center measurements are critical features of crafting the optimal spectacle correction for an athlete. Wrap lens designs potentially can eliminate or reduce some of the aberration and visual field problems found in nonwrap lenses; however, these designs are more commonly found in performance sun eyewear rather than dress eyewear. Wrap design frames and lenses may create problems with induced prismatic effects; therefore careful measurement of the optical centers is necessary with stronger prescriptions.
Spectacle lenses may be a good prescribing option for some noncontact sports and recreational athletes who do not require high-performance optics. Many who participate in golf, tennis, running, cycling, fishing, archery, and shooting sports perform satisfactorily with spectacle corrections. These athletes should be prescribed a suitable impact-resistant lens material and counseled regarding the risks of eye injury with dress eyewear. These athletes also may appreciate the visual performance benefits of CLs, such as elimination of the four field-of-view aberrations and expanded visual fields. Many shooters and archers prefer spectacles over CLs because of the stability of clear vision obtained with spectacle lenses. Because peripheral vision is not a significant factor in most aiming sports, the enhanced visual field does not offer a significant benefit. The shooter or archer is not typically bothered by lens aberrations off the optical center; however, the lenses may need to be fit with the optical centers set for eye position used when aiming with strong prescriptions. The athlete should bring the weapon, carefully unloaded, to the office for this measurement. The practitioner can also arrange to meet the athlete at his or her training facility to make the measurement to generate interest in sports vision services. Additionally, CL movement on the eye can produce undesirable visual fluctuations during prolonged gaze behavior (without blinking) that many shooters and archers develop.
Lens Treatment Options
Ophthalmic lenses are available with a variety of lens treatment options. Most athletes will be bothered by reflections from the lens surface, and reflections off the back surface of the lens are particularly distracting. For example, the tennis player who sees a reflection of the leaves on a tree behind him or her fluttering in a breeze may be bothered by this distraction during the serve or service return. Antireflective coatings are a particularly valuable lens treatment option, and the improvements in technology that allow multilayer antireflective coating have improved the performance of this lens option. The athlete should be warned that antireflective coatings are easy to scratch if the spectacles are not cleaned properly or not kept in a protective case when not in use and that the coating will make dirt and smudges more visible. If polycarbonate lenses are prescribed, an abrasion-resistant coating is provided by the manufacturer because polycarbonate is an inherently soft material and is easily scratched.
Lens fogging and precipitation are two other factors that should be considered in spectacle wearers who compete in predisposing environmental conditions. Condensation appears on spectacle lenses when the temperature of the lenses is lower than the dew point of the surrounding air. Rain, fog, and other moisture in the environment also will produce water drops on the lens surface that can dramatically degrade the athlete’s vision through the lenses. Antifog coatings are available to make the lens surface more wettable so that the moisture forms a thin film on the lens rather than droplets. These coatings also help slough water off the lens surface quicker in wet environments. An antifog coating does, however, interfere with the efficacy of an antireflective coating.
Lens coatings reduce the impact resistance properties of the lens because of the change in surface tension created by the coatings. However, polycarbonate and Trivex lens materials with antireflection coatings have reduced penetration resistance to sharp objects, especially in lenses with reduced center thickness. ,
In many sports, participation exposes the athlete to significant risk for eye injury. Sports involving a ball or fast-moving object, a racquet, a stick, a bat, or body contact have a significant potential for eye injuries (see Table 6.2 for sport risk categories). In 2019, Prevent Blindness America estimated that more than 30,000 eye injuries occur each year from sports participation in the United States. This estimate is recognized as only a fraction of the true incidence of sport-related eye injuries because these injuries represent only those reported from a core of hospital emergency departments in the United States and its territories. There are other methods for determining the true incidence. The Coalition to Prevent Sports Eye Injuries estimates that more than 600,000 eye injuries related to sports and recreation occur each year. Many of the eye injuries sustained during sports participation are preventable with the use of appropriate eye protection. Primary eye care providers must educate all patients about the risks for eye injury during vocational and avocational pursuits, provide information regarding the options for prevention of eye injuries, and direct the patient to ophthalmic services for ocular protection during sports and recreational activities.
|Sport||Minimal Eye Protector||Comment|
|Baseball/softball (youth batter and base runner)||ASTM F910||Face guard attached to helmet|
|Baseball/softball (fielder)||ASTM F803 for baseball||ASTM specifies age ranges|
|Basketball||ASTM F803 for basketball||ASTM specifies age ranges|
|Bicycling||Helmet plus streetwear/fashion eyewear|
|Boxing||None available; not permitted in sport||Contraindicated for functionally one-eyed athletes|
|Fencing||Protector with neck bib|
|Field hockey (men and women)||ASTM F803 for women’s lacrosse |
Goalie full-face mask
|Protectors that pass for women’s lacrosse also pass for field hockey|
|Football||Polycarbonate eye shield attached to helmet-mounted wire face mask|
|Full-contact martial arts||None available; not permitted in sport||Contraindicated for functionally one-eyed athletes|
|Ice hockey||ASTM F513 face mask on helmet |
Goaltenders ASTM F1587
|HECC- or CSA-certified full-face shield|
|Lacrosse (men)||Face mask attached to lacrosse helmet|
|Lacrosse (women)||ASTM F803 for women’s lacrosse||Optional helmet|
|Paintball||ASTM F1776 for paintball|
|Racquet sports (badminton, tennis, paddle tennis, handball, squash, and racquetball)||ASTM F803 for selected sport|
|Soccer||ASTM F803 for selected sport|
|Street hockey||ASTM 513 face mask on helmet||Must be HECC or CSA certified|
|Track and field||Streetwear with polycarbonate lenses/fashion eyewear b|
|Water polo, swimming||Swim goggles with polycarbonate lenses|
|Wrestling||No standard available||Optional custom-protective eyewear|
a Joint policy statement of the American Academy of Pediatrics Board of Directors, February 1996, and the American Academy of Ophthalmology Board of Trustees, February 1995. Revised and approved by the American Academy of Pediatrics Board of Directors, June 2011, and the American Academy of Ophthalmology Board of Trustees, 2013.
b Eyewear that passes ASTM F803 is safer than streetwear eyewear for all sports activities with impact potential.
As previously discussed, dress eyewear or occupational safety eyewear does not offer the impact resistance necessary to protect the wearer from the possible hazards encountered in many sports. Polycarbonate, Trivex, or NXT lens materials provide significantly improved impact attenuation. However, the frame construction of dress eyewear cannot withstand the forces encountered in many sports. Specifically, the materials used for dress eyewear and potentially vulnerable construction of the temple and bridge create endangerments. Similarly, CLs do not offer eye protection for athletes; in fact, rigid CLs may increase the damage to the cornea if they break from a blunt trauma. Many manufacturers have designed eyewear and equipment to protect the athlete during sports participation, and performance standards have been developed to ensure adequate protection for specific sport purposes. ,
The American Society for Testing of Materials (ASTM) is a nongovernmental group that has developed performance standards (F803) for eye and head protection in many sports, including basketball, baseball, racquet sports, field hockey, and women’s lacrosse. ASTM performance standards are established for each sport individually, and the forces potentially encountered in a sport are used to determine appropriate testing parameters. Typically, the protective eyewear is placed on a standard head form and the ball, puck, stick, finger, or elbow is directed at the eyewear from a variety of angles at the predetermined velocity. For example, the eyewear designed for racquet sports must protect the eye and orbit from a squash or racquetball projected at 90 mph from several angles. More details regarding the development of standards and evaluation methods can be found at the ASTM web site ( www.astm.org ). Additional ASTM standards are available for sports in which traditional eyewear designs are inadequate, including protection attached to a helmet for youth baseball batters and base runners (F910), ice hockey (F513), paintball (F1776), airsoft sports (F2879), and skiing goggles and shields (F659). All protective eyewear are also tested for standard D1003, which covers the evaluation of specific light-transmitting and wide-angle, light-scattering properties of transparent materials. The ISO also has sports eye protection standards for skiing goggles (ISO 18527-1) and racquet sports (ISO 18527-2).
Several groups certify equipment to ensure compliance with the ASTM standards for various sports. The Canadian Standards Association (CSA) certifies products that meet Canadian standards for racquet sports (similar to the ASTM standards). The Protective Eyewear Certification Council (PECC) certifies protectors that meet ASTM F803 standards. The Hockey Equipment Certification Council certifies helmets and face shields for use in hockey. For baseball and football helmets and face protectors for football and men’s lacrosse, the National Operating Committee on Standards for Athletic Equipment offers certification. Athletes should use equipment that displays the logo of these certifying bodies to ensure safety ( Fig. 6.1 ). The ASTM standards have proven to be extremely effective in preventing sports eye injuries; no severe eye injuries have been reported for an athlete wearing appropriate eye protection.
To assist athletes in selecting appropriate sports eye protection, the American Academy of Ophthalmology issued a joint policy statement with the American Academy of Pediatrics containing recommended eye protectors for selected sports ( Table 6.2 ). Many publications have provided recommendations for eye protection in sports. , Two basic types of protective eyewear designs are available: a goggle style worn similarly to dress eyewear ( Fig. 6.2 ) and shield-style protection attached to a helmet ( Fig. 6.3 ). Protective sports eyewear must be correctly fit to ensure adequate protection for the athlete. If a young athlete has facial features that are too small to fit any available protective sports eyewear correctly, polycarbonate lenses of 3 mm center thickness should be placed in a children’s frame that meets ANSI Z87.1 standards. This design offers the best chance of eye protection in this situation, although it may not completely protect the athlete from the forces encountered in many sports.
Eye protection can prevent ocular damage in many sports. This chapter focuses on the more common sports in which eye protection is used.
As discussed in Chapter 7 , a significant portion of sport-related eye injuries are caused by racquet sports. , Racquet sports include badminton, handball, racquetball, squash, and tennis; the CSA and ASTM F803 standard and ISO 18527-2 standard are designed to provide protection for any racquet sport. The ball or shuttlecock is hit with tremendous force and can travel at dramatic speeds ( Table 6.3 ). As previously mentioned, the eyewear must protect the eye and orbit from a squash or racquetball projected at 90 mph from several angles, including the side. The hinges are also tested to ensure protection from the forces directed at this potentially weak area. Hingeless frames with straps are recommended when feasible.
|Sport||Shot Type/Record||Speed in kph (mph)|
|Table tennis||Smash record||116 (72)|
|Tennis||Men’s serve record||253 (157)|
|Women’s serve record||210.8 (131)|
Even though the balls used in some racquet sports are larger than the average orbital opening, the compression forces can push the ball deep inside the orbit. The first protective eyewear was designed for use in handball and consisted of a lensless rubber-covered wire frame to reduce the orbital opening ( Fig. 6.4 ). These open eye guards were subsequently used for protection in squash and racquetball. Studies demonstrated that the lack of a protective lens allowed penetration of the ball, potentially resulting in significant eye trauma. The ability of the lensless eye guard to compress the ball actually may increase the risk to the ocular tissues by essentially funneling the ball into the orbit. , Additionally, lensless eye guards offer only limited protection from a racquet injury and are never recommended for use.
Performance requirements for prescription and nonprescription sports protective eyewear for racquet sports (racquetball, squash, and tennis) will have a new ASTM international standard, F3164. The new standard will expand on F803 to address specific requirements for racquet sports and to update the standards to match the advances in these sports.
Many have advocated for protective eyewear use in squash and racquetball and for promoting education regarding the ineffective protection provided by dress eyewear. Dress eyewear with glass or CR39 lenses may increase the risk of severe ocular trauma in racquet sports if the lens shatters on impact. , , , , , Most racquet sport organizations for handball, racquetball, and squash mandate the use of appropriate protective eyewear during competition, and many athletic clubs have instituted eye protection requirements for club play. Similar consideration should be given for mandating appropriate protective eyewear for badminton, especially considering the speed of the shuttlecock in competition.
Ice and Field Hockey
In ice hockey the most common cause of eye injury is from the stick, followed by the puck or opponent. , , With the mandate for face protection in all levels of hockey, except the National Hockey League (NHL), the incidence of eye injuries has significantly declined. No eye injuries have been reported with a full-face shield in use; however, significant trauma has been incurred with a half-face shield. It was unfortunate that for many years the NHL resisted issuing a mandate for face protection, with each season producing examples of the ocular effects of this decision. Beginning with the 2013–14 season, the NHL mandated that all players who have fewer than 25 games of NHL experience must wear a visor properly affixed to their helmet. Furthermore, visors are to be affixed to the helmets in such a fashion as to ensure adequate eye protection. A retrospective study of 10 NHL seasons found significantly increased risk of eye injuries in players who did not wear a visor, and those players were found to be involved in more fights, hits, and penalty minutes. At this time, more than 90% of NHL players use a visor. There are many styles of face protection approved for hockey by ASTM (F513 and F1587) and CSA (CAN3-Z262.2-M78) standards: full-face masks for goaltenders and full-face masks or half visors for other positions ( Fig. 6.5 ). Because of the improved eye safety profile, full-face shields are recommended.
The ASTM F803 standard is recommended for eye protection in field hockey. Similar to the update to the F803 standard described for tennis, field hockey now has a new standard (F2713) specific to the requirements of the sport. A study found significantly higher rates of eye injuries and concussions in states with no protective eyewear mandate for field hockey compared with those that had mandates. , In the states with no mandate, players were more than five times likely to sustain a hockey-related eye injury than those in a state with a mandate. The eye injuries were more serious in states without a mandate and were virtually eliminated in those with a mandate. In addition, the concussion rates were similar between the states, indicating that the use of protection did not result in more aggressive or physical play in the states with a mandate.
Lacrosse has risks for eye injury that are similar to hockey in that the stick and ball present significant hazards. Men’s lacrosse mandates head and face protectors, thereby minimizing the risk for ocular injury. Women’s lacrosse did not mandate face protection until recently, and the incidence and severity of eye injuries that caused many to advocate for compulsory eye protection appear justified by a significant reduction in the number of eye injuries in the year following the mandate. , The ASTM F803 standard is recommended for protection in women’s lacrosse, and wire mesh protectors are favored by the athletes ( Fig. 6.6 ). The women’s lacrosse ball is shot at 45 mph at the eyewear during ASTM testing to determine effective attenuation of the forces encountered in the sport. Similar to the update to the F803 standard described for tennis and field hockey, lacrosse now has a new standard (F3077) specific to the requirements of the sport.
Baseballs have a high incidence of reported eye injuries in the United States, and the sport of baseball has been reported as the leading cause of sport-related eye injuries in children in the United States. , , Risks include being hit with a pitch or a batted or thrown baseball. Spectators are also at risk of injury from batted balls or errant throws. The hardness of the ball has been related to the potential risk for head injury but does not have a significant effect on ocular injuries; the harder the ball, the greater the risk for head and brain injury. The ASTM F910 standard is designed to provide protection for batters and base runners in youth baseball. Approved face guards have provided excellent protection and have good acceptability by athletes and parents. A significant portion of youth baseball players reported vision obstruction (40%) and discomfort (23%) and that they played worse with the face guard (12%); however, 81% believed playing with the face guard was acceptable.
Paintball and Airsoft Sports
War games with paintball guns present a tremendous risk for ocular injury when proper protection is not used. The paint pellet is shot with sufficient energy to cause severe eye trauma; the ASTM F1776 standard therefore establishes specifications for eye protection ( Fig. 6.7 ). Eye injuries have not been reported with the use of ASTM F1776 approved eyewear, although eye injury can occur from a shot that displaces loosely fitting eyewear. Airsoft sports are covered by the F2879 standards; however, other shooting sports are not specifically covered by ASTM standards. The ASTM F803 standard is generally recommended for use as “combat goggles,” and polycarbonate lenses with side shields have been recommended to protect against shotgun spray.
The risk of ocular trauma is relatively low for cross-country and downhill skiers. Tree branches can cause problems and ski pole tips can result in significant damage. The ASTM F659 standard is designed to protect against lens breakage from a ski pole impact. Because the amount of ultraviolet (UV) radiation markedly increases at higher elevations, and snow reflects 85% of the UV radiation, additional risk of photokeratitis exists when appropriate UV filters are not used. Many goggle designs are available with prescription inserts for those who do not wear CLs, although CLs are typically the preferred method for refractive compensation.
Swimming and Water Sports
Swimming and water sports also do not present a significant risk of eye trauma. A study of ocular pathology prevalence in swimmers using goggles for at least 5 years compared with nonswimmers found no significant differences. The elastic band tension, however, can cause swim goggles to snap back and cause severe ocular injuries. Many swim goggles are commercially available, and many designs are available with prescription lenses. , Most swimmers and divers use a goggle or face mask so that no adjustment is necessary to the habitual prescription to compensate for the difference in the index of refraction of the water medium. Some goggle designs have ventilation holes to reduce lens fogging in highly active water sports such as water skiing, surfing, windsurfing, and endurance swimming. A variety of dive masks are also available with prescription inserts or corrective lenses affixed to the faceplate. The air space of the dive mask eliminates the need to change the habitual prescription; however, the increased vertex distance may necessitate an adjustment to the prescription. Water polo presents a risk of blunt trauma from fingers, elbows, or the ball to the improperly protected eye. Swim goggles for water polo should contain polycarbonate lenses to prevent lens breakage, particularly for goalkeepers, who are at a higher risk for facial injury from the ball.
The soccer ball is responsible for most ocular traumas in soccer, although the incidence of eye injuries is relatively low. , , Although the soccer ball is significantly larger than the orbital opening, a portion of the ball will deform and enter the orbit during contact with the high velocities at which the ball is kicked. , A work item for eye protection in soccer (WK1237) was initiated under an ASTM committee for F803, but there were no recommendations produced. Most practitioners recommend the use of ASTM F803 standard eyewear for racquet sports with a secure strap for protection in soccer.
Eye protection may be desirable in many other sports and recreational activities, but no standards exist for those activities. Protective eyewear that meets the ASTM standard for squash often offers the best available protection for athletes unless custom-fabricated protective eyewear can be acquired.
Issues With Protective Eyewear
Some of the common issues causing athletes to be resistant to using protective eyewear are eyewear discomfort, adjustment to wearing eyewear, lens fogging, poor vision (especially visual field constriction), cosmetic appearance, and the perception that it is unnecessary. Athletes who do not habitually wear a spectacle prescription have more difficulty adjusting to wearing eyewear. Adjustment can occur quickly if the eyewear is worn for an extended period (e.g., several hours continuously), and this should be done outside the sport situation to minimize athlete stress during adaptation. This eyewear adaptation training should also help the athlete adjust to the change in peripheral visual field size that may be induced by the frame.
Early studies found that sports protective eyewear constricted the peripheral visual field. The constricted visual field was perceived by 12.5% of subjects using racquetball protectors and was reported to affect visual reaction time (especially with flat lens design eyewear). A study of several types of protective eyewear found that all restricted peripheral vision to some degree but that the restriction did not affect a peripheral reaction task. Some recent studies did not find that sports eye protectors constricted visual fields, , whereas a comparison of hockey visor and sports goggles did find field restrictions but no effect on visual acuity, contrast sensitivity, color vision, or foveal threshold. The decision to wear eye protection becomes a balance between the cost to peripheral vision versus the risk of vision loss.
In highly active sports, and humid or cold environmental conditions, problems with eyewear fogging can occur. All approved protective eyewear has an antifog coating on the lenses and additional antifog solutions are available for supplemental use. Athletes should remove the eyewear when not actively participating in the sport to prevent the rising body heat from condensing on the lenses.
Many athletes are concerned about cosmetic appearance and protective eyewear is not typically appealing to the athlete. Fortunately, protective eyewear has evolved into more fashionable designs with vibrant colors and more options to select from, which will hopefully help earn greater acceptability in some sports. Athletes and sports in which a prevailing attitude of machismo impedes the use of appropriate eye protection will always exist.
Squash is a sport with a significant risk for eye injury and has received the attention of several studies to determine the issues related to the low rates of protective eyewear use in the sport. Many players believe that prescription dress eyewear offers adequate protection, and lensless eye guards may continue to be sold as protection. Among those who do not wear any eyewear during squash, most believed that protective eyewear was unnecessary because of inadequate knowledge of the risks. , , The misperception that experience and expertise reduce the risk for eye injury in squash also exists ; in fact, the amount of time playing squash and the increased speeds encountered at higher levels of play actually increase the risk for injury. , Some squash players were concerned with poor vision and comfort ; however, studies suggest that education regarding injury risk and prevention is an effective motivator to increase eye protection use (especially because a previous eye injury increases use). , , , , ,
Functionally Monocular Athletes
Some athletes would like to compete in sports but have some level of loss of function in one eye. Best corrected visual acuity less than 20/40 (6/12) is often used to determine loss of visual function because this level of impairment begins to affect academic and occupational performance as well as driving privileges. A study of children with an enucleated eye found good compliance with protective eyewear use in sports and that subsequent eye injury to the remaining eye had been successfully averted . In the functionally monocular athlete, the main risk is severe injury to the better eye. Children with amblyopia have a risk of blindness that is more than 15 times higher than those with normal vision (1.75/1000 compared with 0.11/1000), and trauma (including sports trauma) accounts for more than 50% of the resulting blindness.
Functionally monocular athletes should use protective eyewear that meets relevant standards for participation in all sports activities. These same athletes should wear well-built dress eyewear frames containing polycarbonate or Trivex lenses for nonsport activities. Functionally monocular athletes should be discouraged from participating in sports with a risk for serious eye injury in which an effective method of eye protection does not exist, such as boxing, wrestling, and martial arts. ,
Athletes who have had eye trauma or eye surgery that has resulted in a weakening of the ocular tissues should be counseled about the risk of eye trauma in sports. Recommendations for eye protection in sports and recreational activities are made similar to those for the functionally monocular athlete. Specifically, athletes who have undergone radial keratotomy (RK) should be adequately counseled because the procedure significantly weakens the corneal integrity. Modern ablation methods of laser refractive surgery have a lower risk profile compared with RK; however, there is an increased risk of flap dislocation in post-laser in situ keratomileusis (LASIK) eyes for athletes in some sports. ,
Clinicolegal Issues for Protective Eyewear
Eye care providers are in a position that requires appropriate patient counseling regarding eye injury risks and suitable prevention measures. All prescribed or recommended ophthalmic materials are potential sources of legal liability. Legal liability claims can be based on either practitioner negligence or product-based liability resulting from problems with the lenses or frames. Plano eyewear and plano sun eyewear can also be a source of potential liability for the practitioner if proper counseling is not provided. Patients who use CLs or who have undergone laser refractive surgery also need appropriate counseling regarding supplemental eye protection during sports and recreational activities.
Good patient counseling begins with a thorough patient history to determine the specific needs and risk profile for the individual. A lack of knowledge regarding a patient’s sports participation does not protect a practitioner in a liability case if an attempt to elicit that information was not made. Any eyewear recommendations must be made with a thorough knowledge of how that eyewear will be used.
A claim of professional negligence is particularly troubling for a practitioner. Negligence claims involving sports and recreational eyewear typically stem from failure to prescribe the appropriate lens material, failure to warn of potential for breakage (especially with non-impact-resistant materials), or failure to inspect and verify the eyewear before dispensing. , Industry standards play an important role in determining legal liability, and practitioners are expected to understand and comply with those standards. As previously mentioned, polycarbonate or Trivex lenses offer increased impact resistance compared with glass or CR-39; therefore these materials clearly are the recommended choice. The lens material preference should be clearly stated on the prescription provided to the patient; if the patient refuses the recommended lens material, that fact should be adequately documented in the patient record and the patient should be warned of the diminished impact resistance of the alternate material. The impact resistance of a lens material should be discussed without using the words shatterproof or unbreakable because even polycarbonate material will shatter if hit with sufficient force. If a practitioner offers ophthalmic dispensing services, the ancillary personnel responsible for verification and dispensing should be properly educated regarding the industry standards. The lenses should be inspected to ensure that the impact resistance is not compromised by surface treatments or improper edging.
Eye care practitioners are also obligated to counsel the patient on suitable frames for sports and recreational activities. The frames should meet any prevailing ASTM, CSA or ISO performance standards, and the practitioner and dispensing personnel must understand the proper uses for the eyewear and any liability issues. For example, claims have resulted from the recommendation of lensless eye guards for racquetball. , If a patient selects a frame that is not suitable for protection, that fact should be adequately documented in the patient record and the patient should be warned of the diminished impact resistance of both the frame and the lenses (because the frame may not adequately prevent the lenses from displacing back into the eye on impact).
Prescribing Filters and Performance Sun Eyewear
Athletes who participate in outdoor sports and recreational activities require protection from solar radiation. On a bright sunny day, illuminance ranges from 1000 to 10,000 footlamberts, saturating the retina and reducing finer levels of contrast sensitivity. Dark sunglasses aid in recovery of contrast sensitivity and dark adaptation after photoreceptor saturation. The commonly accepted benefits of sun eyewear include protection from sun exposure and ocular trauma, and the reduction of eye fatigue, squinting, and glare disability. The ability of properly selected filters to reduce glare and improve contrast may also produce an enhancement in the ability to discern crucial details and judge depth.
The ocular effects of UV radiation depend on the duration of exposure and the wavelength of the radiation. Prolonged exposure to the middle UV-B waveband has been associated with a variety of ocular problems, including pterygium, pinguecula, cataract, and keratopathy. UV protection provides patients with decreased risks of cataracts, photokeratitis, corneal burns, anterior uveitis, and retinal lesions. , The American Optometric Association recommends 99%–100% protection from near- and middle-UV (UV-A, UV-B) radiation for sun eyewear.
Research on the hazards of high-intensity blue light, defined by European sunglass standards as 380–500 nm, has shown that short-wavelength visible light may create deleterious retinal changes, specifically retinal lesions. , The most harmful wavelength in the visible spectrum for the production of retinal injury appears to be radiation near 440 nm.
The visible light portion of the electromagnetic spectrum is between approximately 380 and 760 nm ( Fig. 6.8 ). The human eye is capable of discerning the entire spectrum of color because of the different wavelengths of light that comprise the chromatic spectrum. Part of the eye’s ability to see artificial (or enhanced) depth is because of the natural chromatic aberration that occurs when monochromatic light is focused on the retina. Because of the differences of wavelength, different colors will refract through the ocular media with different focal points. The difference in focal power between the shorter wavelengths (blue spectrum) and the longer wavelengths (red spectrum) is approximately 2.3 D of focal length. This chromatic aberration results in image blur. Chromatic aberration is cited as the most significant aberration in the well-corrected human eye, , and filters that diminish transmission of the short-wavelength (blue) portion of the visible light spectrum improve retinal image quality by reducing the amount of chromatic aberration.
Visible light is responsible for glare that can cause significant interference with an athlete’s ability to see the visual details critical for successful performance. For example, direct glare from the sun is evident in a blue sky because it affects the visibility of a lofted ball. Reflected glare is exceptionally troubling for athletes when the sun is reflected off surfaces such as water, snow, pavement, and sand. These surfaces reflect horizontally polarized light that can produce substantial glare, particularly water surfaces that are constantly moving. Vertically polarized filters are effective by virtually eliminating horizontally polarized light in the environment.
For an athlete who must compete during the twilight transition hours, the exposure to bright sunlight impedes the initial phase of dark adaptation. , The final level of dark adaptation is elevated, and daily prolonged sun exposure can produce decrements in visual acuity and contrast sensitivity. , , Excessive exposure to bright visible light can result in erythropsia, which is often reported as “red vision” when the individual returns indoors after many hours in the sun. The judicious use of sun eyewear can minimize the impact of bright sunlight on the dark adaptation process and thereby assist the athlete during the transition to artificial lighting conditions. Additionally, the transmission levels of sun eyewear lenses may need to be periodically adjusted in changing sun conditions (e.g., variable cloud cover). An athlete may benefit from a variety of sun eyewear products or a single product with interchangeable lenses or photochromic lenses. Skeet and trap shooters are particularly sensitive to the effects of changing light levels and typically possess eyewear incorporating several filter hues with several tint densities ( Fig. 6.9 ).
Sun eyewear is a tremendous market, and growth in the sports sun eyewear segment has been impressive. Significant innovations in frame design have been made to suit sports demands better, and a trend toward sport-specific lens tinting has been growing. Many manufacturers have invested heavily in research and design to develop light transmission characteristics that purportedly offer performance enhancement features for specific sport demands. Continued innovation in this area can be expected as frame and lens technologies continue to push the envelope of individualized and sport-specific performance. Separating the hype from solid evidence of performance benefits is often difficult, and tint preference is still broadly influenced by individual variations. The transmittance characteristics for each filter are based on the tint colors used, the amount of tint used, and the lens material used. , , The resulting spectral transmission curve is often proprietary for the manufacturer and protected by patent law. The general filter recommendations in this chapter are presented as a guide.
Neutral Gray Tints
Neutral gray tints absorb all wavelengths of the visible light spectrum approximately equally; therefore the natural appearance of colors is preserved. Gray filters often have the lowest transmission properties, so that they perform best in very bright conditions. These filters are preferred by athletes who are sensitive to color information in their sport and who do not appreciate even subtle alteration of the natural environment. Neutral gray tints are often favored by those participating in golf, skiing, and mountaineering activities. Athletes must make critical performance decisions based on subtle terrain details in these sports and distortion of natural contour cues can lead to poor decisions.
Yellow-Brown Range Tints
The process of filtering some of the visible spectrum through the attenuation of the transmittance of the shorter wavelength colors (blue) decreases the chromatic aberration between the longer red wavelengths and the transmitted midrange greens. The reduction in chromatic aberration leads to improved image clarity, and the selective transmission of yellow wavelength light concentrates the visible information at the most sensitive portion of the visible light spectrum. Therefore yellow-range tints filter the glare produced by the short-wavelength light while transmitting peak visible light information with reduced chromatic aberration. Studies have not always been successful in quantifying the improvement in visual acuity and contrast sensitivity reported with yellow tints. Yellow filters have been shown to improve depth perception, contour recognition, and reaction times. Of note, many of these studies were conducted under indoor artificial lighting conditions that are far below the intensity (in candelas per square meter) of natural sunlight and this factor may obfuscate the enhancement effects.
Many athletes appreciate the improvement in contrast with yellow-range tints, especially in low-light conditions such as twilight (dawn and dusk), fog, and heavy cloud cover. Early studies found that objects were more visible in fog with a yellow tint in front of a light. , Of note, outdoor low-light conditions are still substantially more intense than indoor artificial lighting. The common response is that these filters brighten and sharpen the details while enhancing subtle contrast features; however, the effect may be uncomfortable for photosensitive athletes. The improved contrast judgment is most likely caused by the reduction in chromatic aberration induced by the filter. Yellow and brown tints are popular with shooting and snow sport athletes and perform well in fog and low-light conditions. Mountaineers use yellow tints in whiteout conditions to enhance the contrast of environmental features. Thick fog and whiteout conditions produce a Ganzfeld effect, and the reduced chromatic aberration serves to enhance the visibility of low-contrast images. Yellow tints have been used for driving, boating, or flying in low-light conditions; however, the filters distort color perception and can cause problems with traffic signal recognition. A yellow-range tint may be helpful in sports in which an object must be located or tracked against the background of a blue or overcast sky, such as tennis, baseball, and soccer. Studies have demonstrated improved perception of low-contrast contours and faster reaction time for low-contrast targets with yellow tints. ,
Information in the green portion of the visible light spectrum is selectively transmitted by green-range tints. This allows green information to be enhanced and other colors to be relatively muted. Green tints may be preferred in golf, tennis, and woodland shooting. For golf, the green tint enhances the contour information of the grass, and the tint will accentuate the contrast of a brown animal against the green foliage for hunters. Green-range tints have been advocated in tennis to enhance the contrast of the yellow tennis ball against the blue sky; however, the tint can effectively mask the ball against a green background—a common paint color for the court surface and windscreen around the court.
Red-range tints are designed to transmit information selectively at the far end of the visible light spectrum. These filters are widely used in trap and skeet shooting because the reddish orange sporting clay is enhanced against the background of brown dirt, grass, green foliage, or blue sky. Red-range filters also absorb short-wavelength light that contributes to the poor image quality effects of chromatic aberration. These tints are popular in sports in which sharp image clarity is crucial, especially in heavy overcast or foggy conditions. Skiers favor red-range tints for “flat” light conditions and often report enhancement of contrast judgment and depth information with red-range goggles.
Blue-range tints do not offer a substantive benefit for most sports. The selective transmission of short-wavelength visible light does not serve to diminish glare or enhance contrast. In fact, most athletes report that contrast sensitivity is degraded when blue tints are worn outdoors. Some performance sun eyewear appears to have blue-tinted lenses; however, this impression is created by the metallic or iridescent coatings applied to the lens surface.
As previously mentioned, polarized filters are excellent for reducing the effects of reflected glare off horizontal surfaces, especially water, snow, pavement, and sand. Polarized lenses are available in gray, brown, and photochromic lens options. The athlete can choose the lens option best suited for his or her sport demands. Many sports performance sun eyewear products are available with polarized filters and are potentially beneficial for fishing, water sports, driving, and cycling (especially useful for wet surfaces). Despite the widespread acceptance of polarized filters, they may remove important details in some sports. Although the amount of reflected glare from the snow surface is considerable in downhill skiing, crucial details regarding surface conditions (e.g., ice) and contours can be masked by the filters. Several companies offer a variety of golf sun eyewear with polarized lenses; however, one study found that polarized filters did not offer any statistically significant advantage or disadvantage on putting performance over nonpolarized filters. It may be that polarized lenses remove some of the reflectance information from the blades of grass when judging the contours of the green. Another disadvantage of polarized filters is that many liquid crystal displays utilize a polarizer that is set at 45 degrees to aid visibility, which can significantly reduce visibility when viewed through vertically oriented polarized filters. Polarized lenses may interfere with the ability to see instrument displays used in some sport activities, such as cycling, motor sports, or flying.
Photochromic lenses change transmission characteristics in response to changes in light or UV radiation. Photochromic lenses were initially only available in glass lenses, making them unsuitable for many sports activities. Photochromic lenses are now available in CR-39, polycarbonate, and Trivex lens materials, which significantly improve their suitability for some sports. Most photochromic lenses have a gray or brown tint that darkens with exposure to intense sunlight; a photochromic lens that darkens with a polarized filter is also now available. A study comparing activated photochromic lenses with clear lenses found significant improvements in glare disability, glare discomfort, heterochromatic contrast thresholds, and photostress recovery time. Photochromic lenses can be an excellent option for recreational athletes who participate in noncontact sports and who wish to have sun eyewear that is flexible with changing environmental conditions. Many persons who participate in golf, tennis, running, cycling, and fishing perform satisfactorily with spectacle corrections containing photochromic tints. For the competitive athlete, the optical performance of this option may not provide the high performance sought in performance sun eyewear.
Premium sun lenses typically have coatings to help achieve a higher level of optical performance. Most manufacturers use high-vacuum technology to apply several thin layers of coatings. These vacuum deposition coatings are designed to reduce reflections, attenuate transmission of UV and infrared radiation, selectively transmit portions of the visible spectrum (in particular, reduce transmission of short-wavelength light), minimize lens fogging, and improve scratch resistance. The exact nature of the lens coatings, the sequence of the coatings, and the number of layers applied remain proprietary information protected by the manufacturer.
Metallic coatings are used to create a mirrored surface on the front of the lens that effectively reflects incident light. There are two basic types of mirror coatings: metallized and dielectrically coated. The main difference is that metallized coatings not only reflect light, like dielectrically coated mirrors, but also absorb some of the light to reduce overall transmission. Dielectrically coated mirrors can be made in almost any color, and is distinguished from “flash” coatings that have more transparency and less reflection. The use of mirror coatings significantly decreases the amount of light reaching the eye; these coatings are exceptionally effective in sports in which sun intensity can be high, such as snow sports, water sports, beach volleyball, running, and cycling. As some mirror coatings reflect infrared radiation, which produces extra heat, these coatings are useful in sports where the ocular tissues can become overheated, such as endurance sports including running and cycling.
The use of sun eyewear results in a reduction of overall mean luminance. A natural scene in sports contains fine spatial detail that is often of low contrast, which requires a lot of light stimulating the retina in order to resolve some important details (judging a fly ball in baseball, softball, or cricket). The use of filters reduces mean luminance, which means that the ball must subtend a larger area on the retina in order to be seen. This explains why filters may not be useful in some sport situations because the object would need to be closer before the important details could be detected. The issue of visibility and contrast sensitivity at far distances reinforces the need to balance filter color with visible light transmission properties so that the filter is not too dark to discern the target; sometimes more light transmission (e.g., a lighter tint) is optimal in sports applications.
The ANSI standard Z80.3 establishes impact and UV attenuation standards for plano (nonprescription) dress eyewear applied to sun eyewear. , Athletes should be counseled regarding the modest protection offered by premium sun eyewear with polycarbonate or Trivex lenses compared with glass or CR-39 lenses. Sun eyewear should offer protection from both UV-A and UV-B radiation, although manufacturer transmittance claims have been shown to be overestimated. The transmittance curve of a lens product helps determine the level of UV protection. Any polycarbonate lens offers better UV protection than do uncoated glass or CR-39 lenses.
Prismatic effects induced by the lens design of the sun eyewear are another factor that may be noticed by athletes. Contributing factors to prismatic effects include the steep front and back lens curves, the tilt of the lens, lens thickness, and manufacturing abnormalities. Premium sports eyewear was found to have significant amounts of prism in both primary and lateral gaze. Prismatic effects induced by eyewear designs may affect the athlete’s ability to judge depth and location. For example, with yoked horizontal prisms the image is displaced laterally, but if the prisms are oriented in opposing horizontal directions, both the perceived size and distance of the object appear to change. Changes in lateral displacement or apparent size and distance may cause critical errors in sport situations such as golf putting. Most ophthalmic professionals are concerned about the amount of optical distortion present in sun eyewear.
Face-form (wrap) design sun eyewear offers improved coverage of the ocular surface tissues and a wider field of view than traditional designs. The improved coverage increases UV protection by preventing light leakage around the frame and protects the eye from the harmful effects of wind and dust. The expanded visual field afforded by wrap-design eyewear is often offset by the induced prismatic effects of this design. Several eyewear manufacturers have used innovative optical designs to minimize the amount of induced prism, especially in the peripheral aspects of the lens. The result has been wrap-design lenses with an enhanced “sweet spot” viewing area with minimal prismatic distortion. The Nike and Oakley ( Oakley.com ) eyewear designs were found to have the least amount of induced prism in both primary gaze and 30 degrees of lateral gaze directions. Of note, prescription eyewear with a wrap design may need to have the prescription power adjusted to compensate for the wrap.
An excellent fit is required when dispensing sun eyewear for sports use. The frame needs to fit snugly to the face to prevent issues with vertex distance and visual field obstruction from the frame; however, a snug fit can reduce wind exposure while creating fogging problems. Many sports frames are designed to minimize fogging through improved ventilation around the frame and through the nosepiece ( Fig. 6.10 ). The frame should also stay secured to the head so that movement does not dislodge the eyewear. Many manufacturers use rubber and silicone to softly grip the frame to the head at its contact points on the nose bridge and around the ears. The frames should be adjusted so that the touch points of the frame do not create discomfort and the optical centers are aligned in the primary viewing position. Some sports frames have adjustable or changeable temples and nose bridges to provide the athlete with the best possible fit. The specific needs of the female athlete have begun to be addressed by the sun eyewear industry, resulting in better-fitting frames and sport-specific designs. Finally, eyewear designs obviously need to be aesthetically pleasing for any athlete to use it!