In children affected by either unilateral or bilateral cataracts, the indications for surgery and the risk-benefit ratio decisions are more complex than for an adult patient. In an adult, the risks of the procedure are low and the benefits are high, and the presence of a cataract that noticeably degrades vision or alters the patient’s lifestyle is a sufficient indication for surgery.

In a child, additional factors must be considered, such as the health of the child, the availability of resources for perioperative care, and the availability of anesthesiologists who are trained in the care of infants and young children. In adults, the surgery can be scheduled to accommodate the convenience of the patient and the surgeon. In children, the timing of surgery may be dictated by the degree of maturation of the visual system. Surgery may need to be performed urgently to facilitate the effective treatment of amblyopia. In infants with unilateral congenital cataracts, a critical period in visual development exists after birth, during which treatment should be initiated to optimize the possibility for promoting visual development in the affected eye. Evidence suggests that this critical period is before the first 6 to 17 weeks of age, and earlier surgery is felt to minimize deprivation amblyopia.^1,2,3

Another difference is the frequent presence of structural abnormalities of the child’s globe and visual pathways. These abnormalities can influence the visual result that is achieved in these affected children. Affecting the results achieved in all young children are the inherent limitations in the available methods of optical correction and problems with compliance with optical correction and amblyopia therapy. Additionally, persistence with treatment of strabismus, glaucoma, and other related complications is needed to maintain a successful visual result.

Because of the difficulties with correction of aphakia in children, surgery may not be advisable in some cases. For example, observation of a monocular partial lens opacity that decreases visual acuity to 20/40 in an amblyopia-susceptible 2-year-old child may be preferable to making that child aphakic and intolerant of contact lenses or even pseudophakic without the ability to accommodate, and intolerant of glasses with bifocal lenses. The reverse also can be true. Irreversible deprivation amblyopia can be caused by a partial lens opacity, for example, posterior lenticonus, in an infant or a young child. In these cases, the opportunity to achieve high levels of central vision may be permanently lost if surgery is delayed.⁴ Because of these many factors, the accepted 95% success rate for excellent vision following cataract surgery in adults is not possible in children.

Not all cataracts require surgical treatment. Eyes with punctate or small anterior polar cataracts and others with partial opacification of the lens, such as posterior lenticonus, which only slightly interferes with the refraction of light, are best followed and not surgically treated (Fig. 100-1). In preverbal children or in children who are not able to have formal measurements of visual acuity performed, it is up to the surgeon to make the oftentimes difficult decision on the effect that the cataract may have on visual acuity, amblyopia, and visual development. In some cases, it is difficult to determine whether the presence of a partial cataract is responsible for a decrease in visual acuity or whether the refractive error or optical distortion produced by the cataract has produced a mild, reversible form of deprivation amblyopia. In these situations, correction of the refractive error and a trial of occlusion therapy should be attempted. If the visual acuity improves, it may be deduced that amblyopia was responsible for some of the decrease in visual acuity and that the optical distortion produced by the partial cataract is not solely responsible for all of the decrease in acuity.

When a cataract is extensive or if a partial cataract is present and the vision does not improve with a trial of occlusion therapy, cataract surgery should be considered. The guidelines for cataract surgery given in this section are based on the extent of the lens opacity and whether the cataract is isolated to one eye or both. Specific indications for cataract surgery, however, should be considered individually for each child.

Decisions to perform cataract surgery can be difficult when young or developmentally delayed children cannot provide subjective visual acuity responses. In these situations, the decision to remove a cataract depends on the size, density, type, location, and progression of the opacity and the estimated effect of these factors on vision. Estimates of the effect of a partial cataract on vision can at times be difficult, even for experienced examiners; in difficult cases, second opinions can be helpful.⁷

There are few contraindications for performing cataract surgery in children. If a severe life-limiting disease, such as Lowe syndrome or Edward syndrome, is present, cataract surgery should be deferred. Surgery is contraindicated in cases of severe microphthalmia (corneal diameter <5 mm) and in eyes in which the retina is irreparably detached or the posterior segment is disorganized (Fig. 100-6). Because of the risk of extraocular spread of tumor, another contraindication is the presence of untreated retinoblastoma. Surgery is not contraindicated in eyes with successfully treated tumors.¹³

Until three decades ago, it was widely believed that the prognosis for visual rehabilitation of any child with a unilateral congenital cataract was poor.^14,15 Frey et al¹⁶ re-evaluated the treatment of children with monocular cataracts. They were encouraged when three children who had congenital monocular cataracts had 20/40 or better visual acuity. Some surgeons believe that surgery is not indicated when a monocular cataract is first diagnosed in an adolescent. However, a cataract that is presumed to be congenital or of undetermined onset may not have been visually significant at birth or early in infancy, and some visual development may have occurred. In such cases, visual results after cataract surgery on a visually mature child or adult may be much better than assumed.¹⁷ Additionally, cataract surgery should be considered for adults, even when irreversible deprivation amblyopia precludes recovery of central visual acuity. In these situations, the increase in the peripheral visual field on the side of the affected eye may be useful and desirable (Fig. 100-7). An attempt at visual rehabilitation of an eye with a monocular cataract is warranted unless medical contraindications are present, the globe is structurally disorganized, or the risk of complications is high.

The immature visual system of a young child is sensitive to defects that interrupt the focusing of light on the retina. Studies conducted in animals as well as in humans have identified a critical period in visual development during which the immature visual system must be stimulated with focused images on the retina to permit normal visual development.^18,19 If this stimulation does not occur, profound amblyopia develops. When early treatment of a cataract is followed by accurate optical correction and occlusion therapy, stimulation of the retina occurs during the critical period, and a complete reversal of deprivation amblyopia is possible. Conversely, if treatment of a complete cataract is delayed beyond the critical period, complete reversal of the amblyopia may not be possible.

In infants who have complete unilateral congenital cataracts, the critical period for visual development ends at around 17 weeks.² Therefore, the length of the critical period removes infantile cataract surgery from the category of emergency surgery. However, amblyopia is more amenable to treatment when treatment begins as early as possible.¹ An extension of this rationale applies when monocular partial cataracts occur after birth. In these patients, the amblyopia is reversed more easily and completely when treatment begins as soon as possible after the onset of visual deprivation. Therefore, we can assume the existence of similar critical periods in visual development related to visual deprivation, either complete or partial, with an onset not at birth but later during the course of visual development. These periods may be much longer or less rigid because at least some stimulation and development of the visual system occurred. In children who are susceptible to amblyopia, cataract surgery should be performed soon after a visually significant lens opacity is identified.

A critical period for complete reversal of deprivation amblyopia caused by complete bilateral congenital cataracts also exists. Surgery must be performed before the patient is 2 to 3 months old. After this time, the onset of nystagmus owing to sensory deprivation occurs.²⁰ Once this form of nystagmus develops, obtaining visual acuity better than 20/50 is unlikely. Birch et al³ have demonstrated that earlier surgery performed on patients between birth and 14 months of age is associated with improved visual acuity and less amblyopia and that visual acuity when surgery is performed between 14 and 31 weeks of age is independent of age at surgery for these older children with a mean visual acuity of 20/80. Young children with bilateral cataracts should undergo surgery on the eye with the most opaque lens as early in life as safety permits. After surgery has been performed and no untoward effects have been identified, the fellow eye can be treated.

In adolescent patients who have bilateral partial cataracts, surgery may be indicated for the eye with the worst vision to enhance distance visual acuity. If the near visual acuity in the second eye is acceptable, surgery may be delayed for this eye. This treatment plan allows the patient to have the benefit of accommodation and also may allow the patient to take advantage of future advances in surgical techniques or developments in intraocular lens (IOL) technology if the lens opacity increases.

After a decision to perform surgery has been made, it is necessary to decide on the type of aphakic optical correction that will be used. For a child, the ideal optical correction for aphakia should be safe and provide a constant, undistorted focused image on the fovea. This correction should remain effective with growth of the eye, should have optical power and magnification effects similar to those of the natural lens of the fellow eye, and should provide accommodation. Finally, it should provide protection from ultraviolet light and be long lasting and cost-effective.

Available measures for optical correction of aphakia include glasses, contact lenses, and IOL implants. Epikeratoplasty, once used for the optical correction of pediatric aphakia, is essentially no longer performed. All of these forms of aphakic correction have advantages as well as limitations. The decision as to which method of correction is best for any particular patient must be made on a case-by-case basis. Consideration should be given to whether the patient is affected by monocular or binocular cataracts, both now and in the foreseeable future; the patient’s age; and the family or social situation. The optical problems of anisometropia and aniseikonia and concerns for safety and complications with the use of bilateral intraocular lens implants also dictate the choice of optical correction (Tables 100-1 and 100-2).

Aphakic spectacles with bifocals are used principally to correct binocular aphakia in patients who are unable to tolerate contact lenses. In infants and young children, there are difficulties with fitting thick aphakic glasses, and these glasses have optical disadvantages when compared with contact lenses. Patients with monocular cataracts are better rehabilitated with a contact lens or an IOL, avoiding the aniseikonia that a monocular aphakic eyeglass lens would produce.

Contact lenses had previously been the mainstay of treatment of either unilateral or bilateral aphakia in children. Developing confidence in the feasibility and safety of IOL implantation has led to a more widespread use of IOLs in children in recent years; however, contact lenses remain the optical rehabilitation method of choice in infants younger than 1 year of age because of their excellent optical properties, safety, and ability to be changed in power with the changing needs of the growing infant eye. Although the use of contact lenses in older children is being supplanted by IOL implantation, contact lenses remain a viable alternative to IOLs in all patients and are indicated when contraindications to IOL use are present, such as chronic inflammatory disease and some cases of glaucoma. Silicone soft contact lenses and rigid gas-permeable contact lenses are available in powers high enough for the correction of aphakia in the small infant eye, and each type of lens has its advantages and disadvantages.²¹ Silicone lenses can be worn on an extended-wear schedule with removal of lenses only every several weeks for cleaning or, preferably, they may be worn on a daily wear schedule. These lenses are, unfortunately, available only in a limited number of fit and power parameters, and compromises must be made in many patients. Eyes of young infants and especially microphthalmic eyes may have very steep corneal curvatures requiring contact lens base curves of >50.00 D and powers of >30.00 D. Rigid gas-permeable lenses are readily available in custom designs for fit and power, are relatively lower in cost, and with their smaller diameter may be easier for parents to insert and remove. Rigid gas-permeable lenses neutralize astigmatism better than soft contact lenses. Although naps and an occasional night with rigid gas-permeable lenses in place are acceptable, a daily wear schedule is recommended with this type of lens.

Patients with dry eyes, lid abnormalities, or irregular or scarred corneas are poor candidates for contact lenses, as are children with large-amplitude nystagmus. Extensive family commitment is required for the insertion, removal, and care of contact lenses, and lost or damaged lenses are an ongoing financial responsibility. Contact lens intolerance seldom occurs in infants younger than 1 year of age if the parents are motivated and well instructed in the care of the lenses. Some children are, however, psychologically and physically resistant to the insertion, wear, and removal of lenses, either on their initial use or sometimes after an extended period of successful wear. Delayed intolerance of contact lenses occurs most frequently when a child reaches the age of 18 to 36 months and begins to assert more independence. If the family can be motivated to continue over a period of several difficult months, the child frequently gives up fighting over the lenses. Children between the ages of 2 and 5 years are perhaps the most difficult to start using contact lenses, especially traumatic cataract patients, and primary IOL implantation should strongly be considered for these patients. Predicting which children and families will be poorly suited to contact lens wear is difficult, and even the most experienced practitioners and contact lens technicians frequently are surprised by contact lens successes in the seemingly most difficult and resistant of children, provided that the physician, technical help, and parents are motivated for the effort required.

The first contact lens is placed on the eye between 1 and 2 weeks after surgery. The fit of the first lens is determined either from keratometry measurements or from a trial lens fit obtained before surgery. The power of the first lens is determined from the spherical equivalent refraction between 3 and 7 days after surgery. An adjustment in the lens is almost inevitable in the immediate postoperative period, and frequent lens power and fit changes may occur, especially during the first 6 months of life.²² In infants, the power of the contact lens is chosen to produce an overcorrection of -2.50 to -3.00 diopters (D) spherical equivalent to allow clear vision in the near range. When distance acuity becomes of greater importance and growth of the face allows the wear of glasses incorporating a bifocal, around 18 months to 2 years, the contact lens power is then chosen to produce a spherical equivalent overcorrection equal to whatever eyeglass lens may be required for the fellow eye. A bifocal of +2.50 to +3.00 D is then prescribed.

IOL implants provide immediate, constant, high-quality, no-maintenance optical correction of similar magnification to the natural lens. These are all important advantages in children in whom visual rehabilitation and development are influenced by the pediatric issues of amblyopia, development of binocular function, compliance, convenience, and the need for familial care. Although the first implantation of an IOL in a child was performed more than 50 years ago, only over the past 15 years has IOL use in children approached common practice. IOLs are becoming the preferred means of optically correcting older children.²³ Questions, however, remain that are not yet fully answered concerning growth of the eye, power considerations, potential complications, and long-term safety. For economic and legal reasons, the use of IOL implants in patients younger than 18 years of age is not approved by the United States Food and Drug Administration. Nevertheless, with continued investigation and experience, the minimum age at which IOL implantation is recommended and recommendations for bilateral implantation continue to evolve, making IOL use in children more common. IOL implants are an essential option for many, and probably most, pediatric patients older than 1 to 2 years of age.