Accommodative Dysfunction
Many authors have suggested that anomalies of accommodation are commonly encountered in optometric practice.1,2,3,4,5,6,7,8,9,10 Hokoda7 studied a sample of 119 symptomatic patients and found that accommodative dysfunction was the most commonly encountered condition: 25 of the 119 subjects had binocular or accommodative disorders, and 80% of the 25 had accommodative problems. Hoffman, Cohen, and Feuer10 reported on the effectiveness of vision therapy for nonstrabismics, using a sample of 129 subjects. Of the 129 subjects studied, 62% had accommodative dysfunction. In a study of 1,650 children between the ages of 6 and 18 years, Scheiman et al8 found that 2.2% of the children had accommodative excess, 1.5% had accommodative infacility, and 2.3% had accommodative insufficiency. The overall prevalence of accommodative problems was 6%. In a study of 65 university students, Porcar and Martinez-Palomera9 found that 10.8% of the subjects had accommodative excess and 6.2% had accommodative insufficiency, for an overall prevalence of 17%. The more recent population-based Binocular Vision Anomalies and Normative Data (BAND) study11 reported the prevalence of accommodative and nonstrabismic anomalies of binocular vision among schoolchildren in rural and urban Tamil Nadu. The prevalence of accommodative insufficiency was only 0.2%. Wajuihian and Hansraj12 determined the prevalence of accommodative anomalies (insufficiency, excess and infacility) in a sample of 1,211 children (481 male and 730 female), with age range 13 to 19 years. A total of 242 participants (20.2%) had accommodative anomalies. Prevalence estimates were: accommodative infacility 12.9%, accommodative insufficiency 4.5%, and accommodative excess 2.8%. There were no significant differences based on sex, school grade level or study site, except in the prevalence of accommodative infacility, which was significantly higher in the younger than in the older grade level. In a cross-sectional study 175 university students (18 and 35 years old) the authors found accommodative dysfunctions were present in 2.3 per cent of the population.13
One of the early attempts at classifying accommodative anomalies was by Duane in 1915.14 He reported on the results of 170 patients and developed a classification that included insufficiency of accommodation, ill-sustained accommodation, inertia of accommodation, excessive accommodation, inequality of accommodation, and paralysis of accommodation. This classification has received wide acceptance. Many other authors, discussing the classification, diagnosis, and management of accommodative anomalies, have essentially used Duane’s initial classification with minor modifications.1,2,15,16,17,18 The classification of accommodative anomalies that we use in this chapter is also based on Duane’s system and is summarized next.
Classification of Accommodative Anomalies
Accommodative insufficiency
Ill-sustained accommodation
Paralysis of accommodation
Unequal accommodation
Accommodative excess
Accommodative infacility
General Treatment Strategies for Accommodative Dysfunction
SEQUENTIAL MANAGEMENT CONSIDERATIONS
Correction of ametropia
Added lenses
Vision therapy
The concepts that we discussed for the sequential management considerations of binocular vision disorders also apply to accommodative problems. Accommodative fatigue can occur secondary to uncorrected refractive error, such as hyperopia and astigmatism.16 A 3 D hyperope must accommodate 2.50 D for a working distance of 40 cm and an additional 3 D to overcome the hyperopia. The muscular fatigue resulting from 5.50 D of accommodation will often lead to the symptoms associated with accommodative problems. Low degrees of astigmatism and anisometropia can also lead to accommodative fatigue, if the accommodative level oscillates back and forth in an attempt to obtain clarity. It is also not unusual for myopes to experience discomfort when reading with their eyeglasses. This may be due to accommodative fatigue and must be considered in any management plan. The first management consideration, therefore, is correction of refractive error. We recommend applying the same criteria for prescribing that we discussed in Chapter 3.
Added lenses also play an important role in the treatment of accommodative dysfunction. Of the various accommodative problems, accommodative insufficiency and ill-sustained accommodation respond best to added plus lenses. Wahlberg et al19 randomized 22 subjects with accommodative insufficiency to either +1.00 or +2.00 D reading glasses for 8 weeks. The results showed a statistically significant improvement in symptoms in both groups, but only the +1.0 group showed a significant improvement in accommodative amplitude. The important concept is that any accommodative disorder in which the patient is experiencing problems stimulating accommodation will benefit from added plus lenses. Accommodative problems in which the difficulty is with relaxation of accommodation or facility do not respond as well to added lenses. Thus, accommodative excess and accommodative infacility generally require treatment other than added lenses.
Prism, which is so important in cases of binocular vision disorders, is not used for accommodative dysfunction unless there is an associated binocular problem. For the purposes of this chapter, we assume that the accommodative dysfunction is present in isolation. Therefore, prism is not listed as part of the sequential management for accommodative dysfunction.
The final treatment consideration is the use of vision therapy to restore normal accommodative function. Vision therapy is generally necessary in the management of accommodative excess and accommodative infacility. In many cases, it is also critical in the treatment of accommodative insufficiency and ill-sustained accommodation.
Surgery, which was a consideration for binocular vision problems, has no role relative to accommodative dysfunction.
PROGNOSIS FOR TREATING ACCOMMODATIVE DISORDERS
There have been many studies documenting the effectiveness of vision therapy for improving accommodative function, along with several reviews of the literature.20,21,22,23,24 In his review of research into the treatment of accommodative dysfunction, Rouse23 reached the following conclusions:
The literature provides a solid base of research supporting vision therapy as an effective treatment mode for accommodative deficiencies.
Vision therapy procedures have been shown to improve accommodative function effectively and to eliminate or reduce associated symptoms.
The actual physiologic accommodative response variables modified by therapy have been identified, eliminating the possibility of Hawthorne or placebo effects accounting for treatment success.
The improved accommodative function appears to be fairly durable after treatment.
The support in the literature comes from two sources: basic scientific investigation and clinical research. Basic scientists have shown that subjects can learn to voluntarily change accommodative response.25,26,27 These studies demonstrate that voluntary control of accommodation can be trained and transferred to a variety of stimulus conditions. Other researchers have tried to determine the underlying physiologic basis for improved accommodative function. Liu et al3 and Bobier and Sivak27 designed studies to identify which aspects of accommodation are affected by vision therapy. The importance of these two studies is that they used objective procedures to monitor accommodative function. These two investigations clearly demonstrated objective improvement in the dynamics of the accommodative response. The velocity of the accommodative response increased and the latency of the response decreased in both studies. In addition, both studies were able to show that the clinical testing of accommodative facility correlated well with the objective laboratory techniques. This result underscores the importance of the clinical use of accommodative facility testing.
Clinical studies of the effectiveness of vision therapy for accommodative dysfunction have consistently demonstrated excellent success rates. Recently, Scheiman et al24 published the first data from a randomized clinical trial about the effectiveness of vision therapy for the treatment of accommodative problems. They reported that after 12 weeks of treatment, the increases in amplitude of accommodation with office-based vergence/accommodative
therapy (OBVAT) with home reinforcement group 9.9 D, with home-based computer vergence/accommodative therapy (HBCVAT+) group 6.7 D, and home-based pencil push-up (HBPP) therapy group 5.8 D were significantly greater than in the office-based placebo therapy (OBPT) group (2.2 D). Significant increases in accommodative facility were found in all groups (OBVAT: 9 cpm; HBCVAT+: 7 cpm; HBPP: 5 cpm; OBPT: 5.5 cpm); only the improvement in the OBVAT group was significantly greater than that found in the OBPT group. One year after completion of therapy, reoccurrence of decreased accommodative amplitude was present in only 12.5% and accommodative facility in only 11%. The authors concluded that vision therapy is effective in improving accommodative amplitude and accommodative facility in school-aged children with symptomatic convergence insufficiency and accommodative dysfunction.
therapy (OBVAT) with home reinforcement group 9.9 D, with home-based computer vergence/accommodative therapy (HBCVAT+) group 6.7 D, and home-based pencil push-up (HBPP) therapy group 5.8 D were significantly greater than in the office-based placebo therapy (OBPT) group (2.2 D). Significant increases in accommodative facility were found in all groups (OBVAT: 9 cpm; HBCVAT+: 7 cpm; HBPP: 5 cpm; OBPT: 5.5 cpm); only the improvement in the OBVAT group was significantly greater than that found in the OBPT group. One year after completion of therapy, reoccurrence of decreased accommodative amplitude was present in only 12.5% and accommodative facility in only 11%. The authors concluded that vision therapy is effective in improving accommodative amplitude and accommodative facility in school-aged children with symptomatic convergence insufficiency and accommodative dysfunction.
The following retrospective studies included almost 300 patients. Hoffman, Cohen, and Feuer10 reported on a sample of 80 patients with accommodative dysfunction and found an 87.5% success rate for normalizing accommodative ability. About 25 visits, on average, were required. Wold, Pierce, and Keddington28 studied the effect of vision therapy on 100 consecutive patients. They found statistically significant changes in both accommodative amplitude and facility. Patients were seen three times per week, for an average of about 35 visits. In a retrospective study of 114 patients with accommodative dysfunction, Daum18 found that 96% achieved either total or partial success with an average of about 4 weeks of therapy.
Several prospective studies have also been done to control for placebo or Hawthorne effects. In addition to the work done by Liu et al3 and Bobier and Sivak27 discussed earlier, Cooper et al29 used a matched-subjects crossover design to control for placebo effects. They studied five subjects with accommodative disorders and asthenopia. The subjects were divided into control and experimental groups. The experimental group received twelve 30-minute sessions of accommodative therapy, whereas the control group received the same number of sessions of therapy using plano lenses. After the first phase of therapy, the experimental group received an additional 6 weeks of training, identical to that of the control group, and the control group received training identical to that of the experimental group. Four of the five subjects showed increased accommodative amplitude or facility and improvement in symptoms after therapy. These changes occurred only during the experimental phase of the training.
Two other controlled studies30,31 not only showed improvements in accommodative function and elimination of symptoms but also were able to demonstrate a transfer effect on performance. Weisz30 showed that performance on a paper and pencil task improved after accommodative therapy, and Hoffman31 demonstrated improved perceptual performance after treatment.
Another important treatment option for accommodative dysfunction is the use of plus lenses. As discussed later in this chapter, added plus lenses are indicated in accommodative insufficiency and ill-sustained accommodation. Daum32 evaluated the effectiveness of plus lenses for the treatment of accommodative insufficiency. Of the 17 subjects in his study, 53% reported total relief of symptoms, and 35% experienced partial alleviation of their difficulties. A greater percentage of patients received no relief at all with plus lenses compared to vision therapy (12% vs. 4%). This suggests that even for the category of accommodative insufficiency, there are some situations in which vision therapy is the only effective treatment alternative. Daum concluded that “for most patients, it would appear that the relative ease with which the training may be completed (and in view of the optical limitations and inconvenience of a near plus lens addition) makes orthoptic therapy the treatment method of choice.”
Accommodative Insufficiency (Ill-Sustained Accommodation, Paralysis of Accommodation, and Unequal Accommodation)
BACKGROUND INFORMATION
Accommodative insufficiency is a condition in which the patient has difficulty stimulating accommodation. The characteristic finding is an accommodative amplitude below the lower limit of the expected value for the patient’s age. To determine the lower limit for a patient, we suggest using Hofstetter’s formula, which states that the lower limit is equal to 15 − (0.25 × age of patient).33 If the amplitude is 2 D or more below this value, it is considered abnormal. In addition to the low amplitude of accommodation, which is the hallmark of accommodative insufficiency, there are other important characteristics, which are discussed in the next section.
It is important to realize that presbyopia, by definition, is a different entity from accommodative insufficiency. Presbyopia is a condition in which the amplitude of accommodation has diminished to the point at which clear or comfortable vision at the near point is not achievable. This usually occurs between the ages of 40 and 45. The symptoms of presbyopia are identical to those of accommodative insufficiency. However, in presbyopia, the
amplitude of accommodation is not abnormal relative to the patient’s age. Rather, the amplitude is appropriate for the patient’s age, although it is too low to permit clear comfortable vision at near. When we talk about accommodative insufficiency, therefore, we are generally referring to a condition that affects pre-presbyopes.
amplitude of accommodation is not abnormal relative to the patient’s age. Rather, the amplitude is appropriate for the patient’s age, although it is too low to permit clear comfortable vision at near. When we talk about accommodative insufficiency, therefore, we are generally referring to a condition that affects pre-presbyopes.
Ill-sustained accommodation, or accommodative fatigue, has been categorized by most authors as a subclassification of accommodative insufficiency. Both Duane14 and Duke-Elder and Abrams2 described ill-sustained accommodation as an early stage of accommodative insufficiency. It is a condition in which the amplitude of accommodation is normal under typical test conditions, but deteriorates over time. If ill-sustained accommodation is suspected, it is important, therefore, to repeat the amplitude of accommodation measurement several times (Chapter 1). Chase et al34 used a Grand-Seiko WAM 5500 autorefractor to measure accommodative response. They evaluated visual discomfort symptoms using the Conlon survey. They found a strong and positive correlation between accommodative lag and visual discomfort symptoms during near work. The prevalence of accommodative insufficiency was much higher than that estimated by clinical measures. Based on their results, they suggested that accommodative insufficiency and fatigue should be defined and described by objective methods using extended viewing times to assess function. It could be that some of the patients diagnosed with ill-sustained accommodation could have true accommodative insufficiency if assessed with objective recordings or over extended periods of time as suggested by Chase et al.
Another condition that can be categorized under accommodative insufficiency is accommodative paralysis. It is a very rare condition that is associated with a variety of organic causes, such as infections, glaucoma, trauma, lead poisoning, and diabetes. It can also occur as a temporary or permanent consequence of head trauma. Paralysis of accommodation can be unilateral or bilateral, sudden or insidious. If it is unilateral, it leads to the other category of accommodative dysfunction called unequal accommodation. Another possible cause of unequal accommodation is functional amblyopia.
Some authors have found that of the various accommodative problems, accommodative insufficiency is the most common. In a study of the prevalence of accommodative and binocular vision disorders, Hokoda7 found that 55% of the patients with accommodative anomalies had accommodative insufficiency. Daum18 studied 114 patients who had been diagnosed as having accommodative dysfunction and found that 84% had accommodative insufficiency. However, Scheiman et al8 found about an equal mix of the three primary accommodative problems in their study (accommodative excess, 2.2%; accommodative infacility, 1.5%; and accommodative insufficiency, 2.3%). Porcar and Martinez-Palomera9 found that 10.8% of their subjects had accommodative excess and 6.2% had accommodative insufficiency. In the BAND study,11 the prevalence of accommodative insufficiency was only 0.2%. In a sample of 1,211 children, Wajuihian and Hansraj12 found a prevalence of accommodative insufficiency of 4.5%.
CHARACTERISTICS
Symptoms
The symptoms of accommodative insufficiency are presented in Table 12.1. The most common complaints include blur, headaches, eyestrain, double vision, reading problems, fatigue, difficulty changing focus from one distance to another, and sensitivity to light.18 Patients may also complain of an inability to concentrate, a loss of comprehension over time, and words moving on the page. All of these symptoms are associated with reading or other close work. A number of authors have reported a relationship between accommodative insufficiency and academic performance.35,36,37 Borsting, Rouse, and Chu35 reported that children with symptomatic accommodative dysfunction have a higher frequency of behaviors related to school performance and attention. Palomo-Alvarez and Puell36 conducted a cross-sectional study on 87 poor readers and 32 control children 8 to 13 years old. They found that monocular accommodative amplitude was significantly lower in the group of poor readers. Chase et al37 used the Conlon symptom survey38 and an Academic Problems Survey with 68 college students in an attempt to identify a threshold value for the Conlon that predicted academic problems. The Conlon strongly correlated with the Academic Problems Survey, accounting for 62% of variance in selfreported academic problems. A cutoff score of 28 or more was established as a good predictor for problems with grades, homework, and reading. A cutoff score of 27 or more was predictive of accommodative insufficiency. The authors concluded that the Conlon survey is a useful tool to identify students with near work problems that negatively affect academic performance or are associated with accommodative insufficiency.
Some patients with accommodative insufficiency are asymptomatic. For example, Daum18 found that 2% of the patients in his sample had no symptoms, although they clearly had accommodative insufficiency. In such cases, the most likely explanation is avoidance of reading and other close work. Because clinicians generally base their treatment decisions on the presence and severity of the patient’s symptoms, it is important to remember that avoidance should be regarded as a symptom and is as important a reason for recommending therapy as any of the other symptoms associated with accommodative insufficiency.
Table 12.1 SYMPTOMS AND SIGNS OF ACCOMMODATIVE INSUFFICIENCY | ||||||||||||||||||
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Signs
The signs of accommodative insufficiency are presented in Table 12.1. Accommodative insufficiency is a disorder in which the patient experiences difficulty with any optometric testing that requires stimulation of accommodation. Any test that involves the use of minus lenses will generally yield a reduced finding. The most characteristic sign is the reduced amplitude of accommodation. The patient with accommodative insufficiency will also have low findings on the positive relative accommodation (PRA), minus lenses with both monocular accommodative facility (MAF) and binocular accommodative facility (BAF) testing, and more plus than expected with monocular estimation method (MEM) retinoscopy and the fused cross-cylinder test.
Accommodative insufficiency may also be associated with a binocular vision problem. It is not unusual to find a small degree of esophoria in cases of accommodative insufficiency. A likely explanation is that the patient uses additional innervation to try to overcome the accommodative problem, which stimulates accommodative convergence, causing an esophoria. A condition known as pseudoconvergence insufficiency has also been related to accommodative insufficiency.39 In such cases, the patient has difficulty accommodating and therefore underaccommodates relative to the stimulus. As a result, less accommodative convergence is available, the measured exophoria is larger, and a greater demand is placed on positive fusional convergence. Typically, such patients will also have a receded near point of convergence because of the reduced amplitude of accommodation and the lack of accommodative convergence. We presented a case of pseudoconvergence insufficiency in Chapter 9.
ANALYSIS OF BINOCULAR AND ACCOMMODATIVE DATA
The entry point into the analysis of accommodative and binocular vision data is the phoria at distance and near. In cases of accommodative dysfunction, it is not unusual for the phoria to fall outside expected values. As discussed earlier, accommodative insufficiency can be associated with exophoria or esophoria. It is important in such cases to carefully analyze the appropriate group data. For example, the patient in Case 12.1 (discussed later in the chapter) presented with symptoms of blurred vision and eyestrain after reading for 15 minutes. The cover test at distance is ortho, and at near, 2 esophoria. After eliminating refractive error and organic causes, the best initial approach is to be concerned about an esophoria and a problem of the low negative fusional vergence (NFV) type at near. We would therefore analyze the NFV group data, which includes base-in vergence at near, the PRA, BAF testing with minus lenses, MEM retinoscopy, and the fused cross-cylinder test. Case 12.1 illustrates that the indirect measures of NFV are abnormal. The patient has a low PRA and BAF finding, and MEM retinoscopy shows more plus than expected. These data can be a reflection of either an accommodative problem in which the patient has difficulty stimulating accommodation or a convergence excess. The key to differentiating these two hypotheses is the direct measures of NFV. In this case, both the smooth and step vergence findings are essentially normal. This eliminates the possibility of a binocular problem.
Case 12.1 Accommodative Insufficiency
HISTORY
Janet, a 17-year-old 11th grader, presented with complaints of blurred vision and eyestrain after reading for more than 15 minutes. Although she reported similar symptoms throughout high school, the problems had become worse since the beginning of the school year. Her medical history was negative, and she was not taking any medication. Janet had been examined about 2 years ago, and the doctor said her eyes were fine.
EXAMINATION RESULTS
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Pupils were normal, all external and internal health tests were negative, the deviation was comitant, and color vision testing revealed normal function.
CASE ANALYSIS
From the history, Janet’s symptoms seemed to be related to the use of her eyes. Her medical history was negative, and she was not taking any medication. The problems worsened at the beginning of the school year, and her symptoms occurred shortly after the onset of reading. This history tends to suggest a functional rather than organic cause. Because of the esophoria at near, the analysis should begin with the data in the NFV group. The indirect findings (PRA, BAF, and MEM retinoscopy) all suggest a potential problem with NFV. However, the direct findings (base-in vergence at near and vergence facility) are normal. Therefore, the difficulty Janet experiences with minus
lenses does not seem to be due to low NFV. The most likely cause is an accommodative problem. If we analyze the ACC group data, it becomes clear that Janet demonstrates difficulty with all tasks requiring stimulation of accommodation. The low amplitude of accommodation, reduced PRA, poor performance on MAF and BAF testing, and the high MEM retinoscopy result are all characteristic of accommodative insufficiency.
lenses does not seem to be due to low NFV. The most likely cause is an accommodative problem. If we analyze the ACC group data, it becomes clear that Janet demonstrates difficulty with all tasks requiring stimulation of accommodation. The low amplitude of accommodation, reduced PRA, poor performance on MAF and BAF testing, and the high MEM retinoscopy result are all characteristic of accommodative insufficiency.
MANAGEMENT
Reading glasses were prescribed for Janet. The final prescription was based on an analysis of the accommodative and binocular tests and the refraction. Through the subjective, the NRA-PRA relationship showed a need for a +0.75 add, MEM retinoscopy was about +1.00 higher than expected, and the near phoria was 2 esophoria with a 6:1 AC/A ratio. Based on these findings, we prescribed a near vision prescription of +1.25 OD and OS. We asked Janet to wear these glasses for reading over the next 6 weeks, and she returned for a reevaluation at that time.
After 6 weeks, Janet reported complete relief of all symptoms when using the glasses. The reevaluation at this point revealed the following findings through the subjective:
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Although the patient was asymptomatic, the findings continued to show that she had difficulty with accommodative stimulation. We chose not to recommend any additional treatment because she was very content with the result, even though she had to use reading glasses. Another possible option could have been to recommend vision therapy to try to normalize accommodative function, making her less dependent on the reading glasses.
This case is representative of the most common type of accommodative insufficiency. Refractive correction and added lenses are often sufficient to relieve the patient’s symptoms. If the patient continues to experience discomfort or the findings are not normal after wearing the glasses for 4 to 6 weeks, the vision therapy program outlined in Tables 12.3 and 12.4 can be recommended.
Once a binocular vision problem is eliminated, we recommend analysis of the accommodative system (ACC) group data. These data reveal a low amplitude of accommodation and inability to clear −2.00 with MAF, along with the reduced PRA, high MEM finding, and inability to clear −2.00 lenses binocularly. These findings, analyzed as a group, suggest that the patient has difficulty with all tests requiring stimulation of accommodation, confirming a diagnosis of accommodative insufficiency.
DIFFERENTIAL DIAGNOSIS
The differential diagnosis of accommodative insufficiency is presented in Table 12.2. Accommodative insufficiency is considered to be a benign condition, with no serious consequences other than the visual symptoms listed in Table 12.1. It is relatively easy to differentiate from other accommodative disorders. Accommodative insufficiency is the only condition associated with a reduced amplitude of accommodation. In addition, whereas the accommodative insufficiency patient has difficulty with all tests requiring stimulation of accommodation, the accommodative excess patient has difficulty with all tests requiring relaxation of accommodation. The accommodative facility patient has difficulty with both stimulation and relaxation of accommodation. Accommodative paralysis is a condition in which the amplitude of accommodation is dramatically reduced; there is usually some local or systemic disease or medication that can explain the problem.
Although accommodative insufficiency generally has a functional etiology, it may occur in association with primary ocular disease, generalized systemic and neurologic disorders, as well as with lesions that produce focal interruption of the parasympathetic innervation of the ciliary body.9 A variety of ocular and systemic drugs can also lead to accommodative insufficiency. Several comprehensive sources describe these nonfunctional etiologies in detail.15,40 Table 12.2, compiled by London,15 lists the nonfunctional causes of accommodative problems. It is always important to rule out these nonfunctional causes before deciding on any treatment plan for accommodative insufficiency. This differential diagnosis depends very much on the case history. Patients presenting with accommodative insufficiency secondary to any of the diseases listed
in Table 12.2 will have a history of being ill in the past or at the present time. A history of diseases such as diabetes, encephalitis, multiple sclerosis, malaria, and typhoid, for example, would certainly be easy to elicit from a patient with any of these problems. The same is true of the various medications listed in Table 12.2. Accommodative insufficiency secondary to functional causes will present with long-standing chronic complaints and a negative health and medication history.
in Table 12.2 will have a history of being ill in the past or at the present time. A history of diseases such as diabetes, encephalitis, multiple sclerosis, malaria, and typhoid, for example, would certainly be easy to elicit from a patient with any of these problems. The same is true of the various medications listed in Table 12.2. Accommodative insufficiency secondary to functional causes will present with long-standing chronic complaints and a negative health and medication history.
Table 12.2 DIFFERENTIAL DIAGNOSIS OF ACCOMMODATIVE INSUFFICIENCY | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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In most cases, therefore, the differential diagnosis is not difficult. However, if symptoms and findings do not improve as expected when managing a case of accommodative insufficiency that is thought to have a functional basis, it is prudent to reconsider the etiology of the condition.
TREATMENT
We recommend the management sequence listed in Table 12.4.
Lenses
Because uncorrected refractive error can be a cause of accommodative fatigue, we recommend that correction of ametropia be the first management consideration. When dealing with patients with accommodative insufficiency, even small degrees of refractive error may be significant. Prescribing for small degrees of hyperopia, astigmatism, and small differences in refractive error between the two eyes may provide some immediate relief of symptoms for the patient.
Added Lenses
Analysis of the near point findings in accommodative insufficiency clearly shows that these patients benefit from the use of added plus lenses. The low PRA, difficulty clearing minus during accommodative facility testing, the low amplitude of accommodation, and high MEM retinoscopy are all examples of data suggesting the need for plus lenses for near. The amount of added plus can easily be determined by analyzing this data. Referring to Case 12.1, the NRA was +2.50 and the PRA −1.00. This suggests an add of +0.75. This patient could not clear −2.00 lenses during accommodative facility testing, and MEM retinoscopy was +1.00. Because the normal finding is +0.50, this suggests an add of +0.50.
Occasionally, myopic patients will experience difficulty with accommodation after they receive their first prescription or a large change in prescription. Esophoria at near is also a common finding in such cases. If the findings reveal accommodative insufficiency, a bifocal should be prescribed.
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