Risk for glaucoma continues to rise over time following cataract removal in infancy
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In children who underwent cataract removal in infancy, risk for glaucoma is high and continues to rise over a decade, with no difference observed in eyes implanted with an IOL compared with eyes left aphakic, according to a study.
Sharon F. Freedman MD, and colleagues published secondary analysis of the 114 children included in the Infant Aphakia Treatment Study (IATS), a 5-year multicenter trial sponsored by the National Eye Institute comparing the outcomes of unilateral cataract surgery with and without IOL implantation in infants aged 1 to 6 months. All children were seen once again as they reached the age of 10 years to evaluate the cumulative incidence of glaucoma and glaucoma suspect, the potential risk factors other than surgery, and the effects on the retinal nerve fiber layer (RNFL), optic nerve head (ONH) appearance and visual acuity.
In the IATS, children were assigned in equal number to IOL implantation or contact lens use. Two in each group were lost to follow-up. At the 10-year examination, 25 eyes (23%) had developed glaucoma and 21 (20%) were glaucoma suspect. In Kaplan-Meier analysis, the cumulative risk of glaucoma plus glaucoma suspect after cataract removal rose from 12% at 1 year to 31% at 5 years and to 40% at 10 years. No difference was found between eyes implanted or not implanted with an IOL, while small corneal diameter and younger age at surgery was independently associated with a higher risk of developing glaucoma.
By 10 years, approximately 50% of eyes with glaucoma or glaucoma suspect were treated with medications and 48% of eyes had undergone glaucoma surgery. OCT showed no significant decrease in RNFL thickness in eyes with glaucoma or glaucoma suspect and most ONH photographs appeared normal.
Visual acuity was similar among eyes with and without a diagnosis of glaucoma or glaucoma suspect but was better in children who had undergone surgery earlier. “Therefore, the desire to achieve maximum visual acuity must be counterbalanced against an increased risk of glaucoma or glaucoma suspect diagnosis in an infant with a unilateral congenital cataract,” the authors wrote.
This study, they noted, shows that lifelong surveillance for the development of glaucoma is important in children who underwent cataract surgery in infancy, “with the hope that early diagnosis and treatment may facilitate preservation of ONH health and maximal visual function.”
Perspective
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There are three main take-home messages from this study. The first is that eyes operated for congenital cataract in the first 6 months of life will develop high IOP (glaucoma suspect) or verified glaucoma at a rate that approaches 50% by the end of the first decade of life. The rate of glaucoma or glaucoma suspect continues to rise as these children get older, so life-long surveillance is needed. The second important message is that in these infants with congenital cataract, implantation of an IOL is not protective and results in a rate of glaucoma or glaucoma suspect that is at least as high, if not higher, that when eyes are left aphakic. The final take-home message is that micro-cornea (the diameter of the cornea at surgery) emerged as the only risk factor for the development of glaucoma and glaucoma suspect. Micro-cornea is a marker for incomplete anterior segment development and assuredly an underdeveloped trabecular meshwork.
For eyes at risk (those with congenital cataract and micro-cornea/microphthalmia who need surgery early in life), life-long surveillance is very important. It is remarkable that this study documents no significant difference in visual acuity and optic nerve fiber thickness between glaucoma/glaucoma suspect eyes compared with those with normal IOP. Because this was a funded multicenter clinical trial, coordinators and surgeons developed a very close communication relationship with these families. Infants operated for congenital cataracts outside of a study need this same intensity of communication and follow-up. If not, then the incidence of severe glaucoma damage is likely to be much higher, owing to the lack of early diagnosis and properly timed medical or surgery treatment of high IOP.
It will be essential to follow this carefully selected and closely studied cohort until adulthood to document any additional adverse events. In addition, it is important for surgeons to not generalize these data to children with acquired developmental cataracts who are operated after the initial 6 months of life. We (under the title of TAPS, Toddler Aphakia and Pseudophakia Study) recently published data from children operated for developmental cataracts from 7 to 24 months of life. These children have a markedly lower risk for glaucoma and a very low rate of micro-cornea.
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