tests and visually evoked potentials can provide additional quantitative information (see Chapter 1). In older children, particularly those with lamellar or posterior subcapsular cataracts, glare testing may be useful for assessing decreased vision.

Ocular examination

Slit-lamp examination can help classify the morphology of the cataract and reveal associated abnormalities of the anterior segment. If the cataract allows some view of the posterior segment, careful examination of the optic nerve and fovea should be performed. If no such view is possible, B- scan ultrasonography is required in order to assess for gross anatomical abnormalities of the posterior segment. The presence of retinal or optic nerve abnormalities cannot be definitively ruled out, however, until the posterior pole can be visualized directly. See Table 23-3 for additional information.

Table 23-3

Workup

Unilateral cataracts are not usually associated with occult systemic or metabolic disease; laboratory tests are therefore not warranted. In contrast, bilateral cataracts may be associated with many systemic and metabolic diseases. If the child has a positive family history of isolated congenital or childhood cataract or if examination of the parents shows lens opacities (and there are no associated systemic diseases to explain their cataracts), systemic evaluation and laboratory tests are not necessary. A basic laboratory evaluation for bilateral cataracts of unknown etiology in apparently healthy children is outlined in Table 23-3.

Further workup should be directed by the presence of other systemic abnormalities. Evaluation by a geneticist may be helpful for determining whether there are associated disorders and for counseling the patient’s family regarding recurrence risks.

Cataract Surgery in Pediatric Patients

Timing of the Procedure

Once a decision has been made to remove the cataract(s), the next issues to be resolved are (1) when to perform surgery and (2) whether to implant an intraocular lens (IOL). In general, the younger the child, the greater the urgency to remove the cataract, because of the risk of visual deprivation amblyopia. For optimal visual development in newborn and young infants, a visually significant unilateral cataract should be removed before age 6 weeks; visually significant bilateral cataracts, before age 10 weeks.

For older children with bilateral cataracts, surgery should be recommended when the level of visual function interferes with the child’s visual needs. Although children with best-corrected visual acuity of roughly 20/70 may function relatively well in early grade school, their participation in important activities of daily living such as unrestricted driving will be restricted later in life in parts of the United States and elsewhere. Surgery should be considered when visual acuity decreases to 20/40 or worse. For teenaged patients, cataract surgery may be indicated when the visual requirements for obtaining a driver’s license need to be met.

For older children with unilateral cataract, cataract surgery is suggested when optical treatment and amblyopia therapy cannot improve visual acuity beyond 20/40.

Intraocular Lens Use in Children

The choice of optical device for correction of aphakia depends primarily on the age of the patient and the laterality of the cataract. IOL implantation in children aged 1–2 years and older is widely accepted. The use of IOLs in younger infants, however, is controversial because of a higher rate of complications and the rapid shift in refractive error that occurs during the first 1–2 years of life. It has been shown that, compared with contact lens rehabilitation in aphakic patients, IOL implantation in infants aged 1–6 months is associated with a significantly higher rate of adverse events requiring further surgery, but it is not associated with a significant difference in grating visual acuity at age 1 year. In cases without significant posterior pole abnormalities, it is possible to obtain some degree of central vision and, occasionally, excellent vision if early surgical intervention is followed by consistent contact lens wear and patching of the uninvolved eye for treatment of amblyopia. In most infants who are left aphakic, secondary IOL implantation can be performed after 1–2 years of age.

The Infant Aphakia Treatment Study showed that aphakic infants with mild PFV treated with contact lenses had a higher incidence of adverse events after lensectomy compared with children with other forms of unilateral cataract. However, both groups had similar visual outcomes 1 year after surgery.

Lambert SR, Buckley EG, Drews-Botsch C, et al; Infant Aphakia Treatment Study Group. A randomized clinical trial comparing contact lens with intraocular lens correction of monocular aphakia during infancy: grating acuity and adverse events at age 1 year. Arch Ophthalmol. 2010;128(7):810–818.

Morrison DG, Wilson ME, Trivedi RH, Lambert SR, Lynn MJ; Infant Aphakia Treatment Study Group. Infant Aphakia Treatment Study: effects of persistent fetal vasculature on outcome at 1 year of age. J AAPOS. 2011;15(5):427–431.

Management of the Anterior Capsule

To allow access to the lens nucleus and cortex during cataract surgery, a capsulorhexis is performed. Because the tearing characteristics of the pediatric capsule are quite different from those of the adult capsule, lens removal techniques are modified for pediatric patients so that the risk of inadvertent extension of the tear is minimized. The elasticity of the capsule is greatest in younger patients, especially infants, making continuous curvilinear capsulorhexis more difficult in these patients. The pulling force should be directed nearly perpendicular to the direction of intended tear, and the capsule should be regrasped frequently to maintain optimal control over the direction of tear. The use of a 2- incision push-pull technique may be helpful (Fig 23-6). An alternative to capsulorhexis in infants is vitrectorhexis, the creation of an anterior capsule opening using a vitrectomy instrument. In children with opaque capsules, visibility can be enhanced with application of trypan blue ophthalmic solution 0.06% to the capsule.

Figure 23-6 In the 2-incision push-pull rhexis technique, 2 small linear incisions are made in the superior and inferior lens capsule (A), and the center of the flap of the superior incision is grasped (B); pushing to the center of the pupil will result in a semicircular tear (B). The tear is extended to the center of the capsule, between the sites of the initial stab incisions (B). C, The flap of the inferior stab incision is then grasped and pulled to the center of the pupil, forming another semicircular tear. D, The semicircular tears are joined to form a complete, continuous curvilinear capsulorhexis. (Redrawn with permission from Hamada

S, Low S, Walters BC, Nischal KK. Five-year experience of the 2-incision push-pull technique for anterior and posterior capsulorrhexis in pediatric cataract surgery. Ophthalmology. 2006;113(8):1309–1314.)

Lensectomy Without Intraocular Lens Implantation

In children who will be left aphakic, lensectomy is performed through a small limbal or pars plana incision with a vitreous-cutting instrument (vitrector). Irrigation can be provided by an integrated infusion sleeve or by a separate cannula. Ultrasonic phacoemulsification is not required, as the lens cortex and nucleus are generally soft in children of all ages. It is important to remove all cortical material because of the propensity for reproliferation of pediatric lens epithelial cells. Tough, fibrotic plaques such as those occasionally encountered in severe PFV may require manual excision with intraocular scissors and forceps.

Because posterior capsule opacification occurs rapidly in young children, a controlled posterior capsulectomy and anterior vitrectomy should be performed at the time of cataract surgery in children who are unlikely candidates for awake Nd:YAG capsulotomy, which would otherwise be necessary within 18 months of the primary surgery. This technique allows for rapid, permanent establishment of a clear visual axis for retinoscopy and prompt fitting and monitoring of the aphakic optical correction. If possible, sufficient peripheral lens capsule should be left to facilitate secondary

posterior chamber IOL implantation at a later date.

Lensectomy With Intraocular Lens Implantation

Single-piece acrylic foldable IOLs, which can be placed through a 3-mm clear corneal or scleral tunnel incision, have become popular in pediatric cataract surgery, although larger single-piece polymethylmethacrylate (PMMA) lenses are also still used. Silicone lenses have not been well studied in children.

If an IOL is to be placed at the time of cataract extraction, 2 basic techniques can be used for the lensectomy, depending on whether the posterior capsule will be left intact. Many pediatric cataract surgeons leave the posterior capsule intact if the child is approaching the age when an awake Nd:YAG capsulotomy could be performed (usually 5 years of age). Primary capsulectomy is usually preferred for younger children. Studies have shown that in early childhood, the lens capsule opacifies, on average, within 18–24 months after surgery, but this can vary considerably.

Technique with posterior capsule intact

After the cortex is aspirated, the clear corneal or scleral tunnel incision is enlarged to allow placement of the IOL. Placement in the capsular bag is desirable, but ciliary sulcus fixation is an acceptable alternative. The surgeon should remove all viscoelastic material to prevent a postoperative spike in intraocular pressure (IOP). Closure of 3-mm clear corneal incisions with absorbable suture has been shown to be safe and does not induce astigmatism in children.

Techniques for primary posterior capsulectomy

Posterior capsulectomy/vitrectomy before IOL placement After lensectomy, the vitrector settings should

be set to the low-suction, high-cutting rate appropriate for vitreous surgery. A posterior capsulectomy with anterior vitrectomy is then performed. The anterior capsule is enlarged, if necessary, to an appropriate size for the IOL, and the lens is implanted in the capsular bag, if possible, or in the ciliary sulcus as an alternative. The surgeon must take care to ensure that the capsulotomy does not extend, the IOL haptics do not go through the posterior opening, and vitreous does not become entangled with the IOL or enter the anterior chamber.

Posterior capsulectomy/vitrectomy after IOL placement Some pediatric cataract surgeons prefer to place

the IOL in the capsular bag, close the anterior incision, and approach the posterior capsule through the pars plana. Irrigation can be maintained through the same anterior infusion cannula used during lensectomy. A small conjunctival opening is made over the pars plana, and a sclerotomy is made with a microvitreoretinal (MVR) blade 2.5–3.0 mm posterior to the limbus. This provides good access to the posterior capsule, and a wide anterior vitrectomy can be performed.

Intraocular lens implantation issues

Because the eye continues to elongate throughout the first decade of life and beyond, selecting an appropriate IOL power is complicated. Power calculations in infants and young children may be unpredictable for several reasons, including widely variable growth of the eye, difficulty obtaining accurate keratometry and axial length measurements, and use of power formulas that were developed for adults rather than children. Studies have shown that the refractive error of aphakic pediatric eyes undergoes a variable myopic shift of approximately 7.00–8.00 D from age 1 to age 10, with a wide standard deviation. This suggests that if a child is made emmetropic with an IOL at age 1 year, refraction at age 10 years would be up to –8.00 D or greater. Refractive change below age 1 year is even more unpredictable. This approach assumes that the presence of an IOL does not alter the normal growth curve of the aphakic eye, an assumption that may not be valid based on both animal