Recognition acuity versus age at surgery for children treated for a dense unilateral congenital cataract showing a better fit with a bilinear than a linear model (Used with permission from Birch and Stager )
Visual outcome data for 112 children treated for a dense unilateral congenital cataract in the Infant Aphakia Treatment Study: (a) Scatterplot of recognition visual acuity at 4.5 years of age versus age at cataract surgery; (b) Plot comparing recognition visual acuity at 4.5 years of age versus age at cataract surgery (Used with permission from Hartmann et al. )
Bilateral Cataract Surgery
It is generally believed that bilateral congenital cataracts should be removed by 8 weeks of age to achieve the best visual outcomes. Lambert and coworkers  evaluated the long-term visual outcomes for 43 children with dense bilateral congenital cataracts and found a linear relationship between the age of cataract surgery and the visual acuity in the better seeing eye (correlation coefficient = 0.28) (Fig. 18.3). They noted that delaying cataract surgery to 10 week of age or later increased the likely of a poor visual outcome (20/100 or worse). In contrast, Birch and coworkers  reported a bilinear relationship between the age of surgery and the visual outcome in 37 infants with dense bilateral congenital cataracts. Between birth and 14 weeks of age they noted a progressively worse visual outcome the older a child was at the time of cataract surgery (visual acuity decreased by 1 line with each 3 week delay in surgery). However, after age 14 weeks until 31 weeks, the visual outcome was independent of age at the time of cataract surgery (Fig. 18.4). These two studies suggest that unlike children with unilateral congenital cataracts, children with dense bilateral congenital cataracts do not have a well-defined latent period. However, other considerations such as the increased risk of glaucoma associated with very early cataract surgery and comorbidities should dictate the timing of cataract surgery.
Best corrected visual acuity (BCVA) at 5 years of age in the better seeing eye versus age at surgery for 43 children treated for dense bilateral congenital cataracts. Symbols indicate the status of nystagmus at the initial exam. Dotted lines indicate BCVA of 20/80 and age of 10 weeks (Used with permission from Lambert et al. )
Long-term visual outcome data for 37 children treated for dense bilateral congenital cataracts along with the best-fit linear model of the critical period (Used with permission from Birch et al. JAAPOS. 2009;13:67–71)
18.2.2 Cataract Morphology
The type of cataract has been reported to be a predictor of the visual outcome . However, confounding variables make it difficult to ascertain the relative contribution of the type of cataract on the visual outcome. Certainly the density of lens opacities and the age of onset are important considerations. For example, eyes with partial cataracts that are acquired after birth (e.g. posterior lentiglobus and lamellar cataracts) are usually associated with better visual outcomes (Fig. 18.5) than cataracts associated with dense congenital opacities such as nuclear cataracts (Fig. 18.6) . Cataracts arising from persistent fetal vasculature (PFV) have been reported to have a worse visual prognosis, but eyes with PFV vary greatly in their severity and some subtypes may be associated with good visual outcomes . While personal photographs may allow the age of onset of cataracts to be ascertained in some instances , it is still difficult to ascertain the rate that cataracts progress using photographs alone.
Lamellar cataract in a 2-year-old child
Dense nuclear cataract in a newborn
18.2.3 Amblyopia Therapy
Occlusion therapy is critical for the successful visual rehabilitation of children with a unilateral congenital cataract after cataract surgery. Selected children with bilateral congenital cataracts also require occlusion therapy after cataract surgery. Little is known about the best patching regimen to optimize visual acuity and binocular vision following unilateral congenital cataract surgery. Lambert and coworkers  reviewed the medical records of 9 children who underwent unilateral congenital cataract surgery when 6 weeks of age or younger. All of these children were compliant with patching therapy until 12 months of age and optical correction until 6 years of age. At age 12 months, the fellow eyes were patched a mean of 6.7 h/day. However, by 6 years of age, patching had declined to a mean of 1.7 h/day. Furthermore, 4 of the 9 children abandoned patching therapy entirely between the ages of 3 and 6 years. Nevertheless, visual acuity only worsened in one child after the cessation of patching therapy suggesting that visual acuity was not adversely affected by early termination of patching therapy provided the correct optical correction was being worn by the child.
Patching regimens for children with unilateral aphakia, unlike patching regimens for children with anisometropic and strabismic amblyopia [15, 25, 36], are not evidence based. However in recent years, there has been a trend to reduce the number of hours that patients are patched each day to potentiate the development of binocular vision in these children [18, 21]. Patching a child for longer than 6 h each day probably does not improve the visual outcome and may contribute to the loss of binocularity and contribute to the development of strabismus. This is illustrated by two case studies from my clinical practice. Both of these children underwent unilateral congenital cataract surgery during early infancy and both achieved 20/20 visual acuity in their aphakic eyes. However, Patient 1 had the fellow eye patched nearly full-time for 2 ½ years and now has no stereopsis and has required two strabismus surgeries to achieve satisfactory ocular alignment. In contrast, the fellow eye of Patient 2 was never patched for more than 6 h a day and patching was tapered beginning at age 14 months. These cases illustrate that good visual outcomes can be achieved with part-time patching. In addition, part-time patching may facilitate the development of binocular vision. Based on the excellent visual and stereopsis outcome achieved with the patching regimen for Patient 2, I now advise parents to only patch their child’s fellow eye for one-half of their waking hours until age 14 months. I then advise them to gradually reduce the frequency of patching until age 7 years when I recommend patching therapy be discontinued.
A child with a dense nuclear cataract in his left eye underwent a lensectomy at age 3 weeks. Immediately after cataract surgery, he was treated with an extended wear contact lens and patching therapy of his fellow eye for one-half of his waking hours. At age 8 months, his patching therapy was increased to 9 ½ h/day and then increased to 11 h/day at age 18 months. This patching regimen was then maintained for the next 2 ½ years. At age 4 years, his patching therapy was gradually tapered (age 4 years: 10 h/3 days a week; 4 ½ years: 6–7 h/day; 5 years: 4 h/3 days; and 6 years: 4 h/2 days a week) and then discontinued at age 7 ½ years. At age 10 months he underwent a left medial rectus recession to correct an esotropia. At age 17 years, his left medial rectus muscle was advanced to correct a consecutive exotropia. At age 21 years, an intraocular lens was implanted in the left eye. At age 30 years (Fig. 18.7), his best corrected visual acuity was 20/15 in the right eye and 20/20-2 in his left eye. He reports using his left eye for reading at night since he only has low myopia in this eye, but high myopia in his right eye. He has never had measurable stereopsis and his exotropia has recurred.
A dense cataract was diagnosed in the left eye of this patient as a newborn. At age 3 weeks, a lensectomy was performed and he wore an aphakic contact lens until age 21 years when an intraocular lens was implanted in the sulcus. He received nearly full-time patching therapy of his right eye until age 4 years. He is now 30 years old and has visual acuity of 20/15 in his right eye and 20/20 in his left eye. He has undergone two strabismus surgeries and continues to have a dissociated vertical deviation and a small angle exotropia. He has no stereopsis
A child with a dense nuclear cataract in her left eye underwent a lensectomy at age 6 weeks. One week after cataract surgery, she started wearing an extended wear contact lens on her aphakic eye and began patching her fellow eye 1 h/day. Patching was gradually increased by 1 h/day/month of life until she was being patched 6 h/day. Patching was maintained at this level until age 14 months, when patching was reduced to 5 h/day. Patching was then slowly tapered (age 2 ½ years: 3–4 h/day; 3 years: 2 h/day; 4 years: 4 h every other day; and 5 years: 4 h/day twice a week) and then discontinued at age 7 ½ years. At age 12 years (Fig. 18.8), her best corrected visual acuity was 20/20 in both eyes. She was orthophoric and had 120 s/arc of stereopsis using the Randot stereoacuity test.
Twelve year old patient who was diagnosed with a dense cataract in the left eye as a newborn. At age 6 weeks, a lensectomy was performed on her left eye. Postoperatively, her left eye was corrected optically with a contact lens and she underwent part-time patching therapy of her right eye until age 7 years. She continues to wear an aphakic contact lens on her left eye. She is orthophoric and has 120 s/arc of stereopsis. Her best corrected visual acuity is 20/20 in both eyes
Nystagmus occurs commonly in children with bilateral congenital cataracts. If cataracts are left untreated, nystagmus usually develops between the ages of 10 and 12 weeks. Lambert and coworkers  reported that in children with bilateral congenital cataracts, preoperative nystagmus was a better predictor of a poor visual outcome than age at cataract surgery (Fig. 18.3). Only 38 % of children with preoperative nystagmus developed a best corrected visual acuity of 20/40 or better compared to 74 % of children with no preoperative nystagmus. Children with preoperative nystagmus underwent cataract surgery at a mean age of 18 weeks compared to 8 weeks for children undergoing cataract surgery without nystagmus. Young and coworkers  also found that nystagmus was a predictor of a worse visual outcome in children with bilateral congenital cataracts. However, they reported that most children developed nystagmus after cataract surgery, rather than before cataract surgery. While nystagmus can develop after cataract surgery, this is unusual. It is likely that the nystagmus was present preoperatively, but not documented since this was a retrospective chart review.
18.2.5 Type of Optical Correction
The type of optical correction worn probably does not affect the visual outcome in children with congenital cataracts provided the optical correction is worn on a consistent basis. However, compliance may be better with certain types of optical corrections than others. The Infant Aphakia Treatment Study found that children with a unilateral congenital cataract had similar visual outcomes at age 4 ½ years if an eye underwent primary IOL implantation or was left aphakic and corrected with a contact lens (Fig. 18.9) . Birch and coworkers  also reported similar visual outcomes in children with dense unilateral cataracts after cataract extraction with or without IOL implantation when patients had good-to-excellent contact lens compliance. However, they reported worse visual outcomes in eyes left aphakic and treated with contact lenses when contact lens compliance was moderate-to-poor. Another case series reported similar visual outcomes in 15 children who underwent bilateral congenital cataract surgery coupled with primary IOL implantation compared to 18 children who underwent bilateral lensectomies and were initially optically corrected with contact lenses and only later underwent secondary IOL implantation . Therefore the type of optical correction does not appear to be a major factor in determining the visual outcome if there is good to excellent compliance with the optical correction.
Histogram of recognition visual acuity at age 4.5 years by treatment group (CL contact lens, IOL intraocular lens) for 112 children treated for a dense unilateral congenital cataract in the Infant Aphakia Treatment Study. The median visual acuities were 0.90 logMAR (20/159) for both groups. LP indicates light perception, LV low vision (Teller Acuity Card), NLP no light perception (Used with permission from The Infant Aphakia Treatment Study Group )
18.104.22.168 Visual Outcomes
Bilateral Congenital Cataracts
Pattern of Visual Recovery
Maurer and coworkers  evaluated the pattern of visual recovery following unilateral and bilateral congenital cataract surgery in children treated with aphakic contact lenses. They noted on average a 0.40 octave improvement in monocular acuity in the treated eye 1 hour after contact lens correction and another 0.60 octave improvement 1 month later. The pattern of improvement was similar for unilateral and bilateral cataracts and was not related to age at the time of cataract surgery. They hypothesized that patterned visual input alone supports some visual improvement independent of any competitive interaction with the fellow eye.
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In a recent multi-center series from the U.S.A., 28 % of children who underwent bilateral congenital cataract surgery at a mean age of 11.5 weeks were able to see 20/30 or better in their better seeing eye after long-term follow-up (Fig. 18.3) . Furthermore, none of these children had a visual outcome worse than 20/100. Similar visual results have been reported in a series from Sweden (Table 18.1) . In contrast a recent series from India reported that only 22 % of children with bilateral cataracts were able to see 20/60 or better in their better seeing eye after cataract surgery and 59 % had a visual outcome worse than 20/200 . One of the likely causes for the worse visual outcomes in India was that cataract surgery was often delayed until later in childhood; only 18 of the 46 (38 %) children in the study underwent cataract surgery before 6 months of age. There was even a greater delay in cataract surgery in a series reported from Tanzania. Cataract surgery was performed at a mean age of nearly 4 years. However, since only 25 % of these children had preoperative nystagmus, it is likely that some of these children had acquired cataracts .