Infant Cataract Surgery Increases Long-Term Glaucoma Risk, Regardless of IOL Implants

Among children who underwent unilateral cataract removal in infancy, risk of glaucoma-related adverse events continues to increase with longer follow-up and is not associated with primary intraocular lens (IOL) implementation, according to research published in JAMA Ophthalmology.

Glaucoma—characterized by progressive retinal ganglion cell apoptosis and subsequent visual field defects—is the second leading cause of blindness worldwide and can occur as a result of childhood cataract removal, researchers explained.

However, frequency and risk factors of this event vary by study population, definition, and follow-up time, while effects of primary IOL implementation during surgery in young children are difficult to evaluate, due to a lack of randomized trials.

To better characterize this adverse event, investigators conducted a secondary analysis of The Infant Aphakia Treatment Study (IATS), a multicenter, randomized, controlled clinical trial sponsored by the National Eye Institute. The original study aim was to compare surgery outcomes for unilateral cataract with or without primary IOL implantation in infants who underwent cataract removal surgery between ages 1 to 6 months.

Researchers collected 10-year surgical outcomes using optic nerve head (ONH) photographs and assessing peripherally retinal nerve fiber layer thickness (RNFL) via spectral-domain optical coherence tomography.

In addition, “Standard definitions of glaucoma and glaucoma suspect were developed and uniformly applied for surveillance and diagnosis of eyes within the IATS, with the former requiring not only elevated intraocular pressure but also associated structural changes in the infant eye or need for glaucoma surgery,” the authors wrote.

A total of 114 infants were originally randomized in the trial; 110 (96.5%) of them completed clinical examination at age 10.5 years. Fifty-seven patients initially received IOLs whereas the other 57 remained aphakic (contact lens [CL] group). At 10 years, patients had a mean (SD) age of 10.6 (0.3) years and 55 were included from each group for follow-up analyses. Mean postsurgical follow-up time was 10.4 years and glaucoma status was available for 106 participants (55 IOL and 51 CL) at this time.

At 10 years, 25 eyes (23%) developed glaucoma, with 21 eyes (20%) developed glaucoma suspect, for a total 46 operated-on eyes (40%) with glaucoma plus glaucoma suspect diagnosis. Thirteen eyes (25%) in the CL group developed glaucoma and 13 (25%) developed glaucoma suspect. In the IOL group, 12 eyes (22%) and 8 eyes (15%) developed glaucoma and glaucoma suspect, respectively.

Kaplan-Meier analyses found:

• For all study eyes combined (n = 114), risk of glaucoma after cataract removal rose from 9% (95% CI, 5%-16%) at 1 year, to 17% (95% CI, 11%-25%) at 5 years, to 22% (95% CI, 16%-31%) at 10 years.
• Risk of glaucoma plus glaucoma suspect diagnosis after cataract removal rose from 12% (95% CI, 7%-20%) at 1 year, to 31% (95% CI, 24%-41%) at 5 years, to 40% (95% CI, 32%-50%) at 10 years.
• Risk of glaucoma and glaucoma plus glaucoma suspect diagnosis at 10 years was not significantly different between treatment groups.
• By 10 years, glaucoma surgery had been performed in 11 of 25 eyes (48%) with glaucoma (7 requiring a single surgery by the 10-year examination).
• Eyes with glaucoma (compared with eyes with glaucoma suspect or neither) had longer axial length but relatively preserved RNFL and similar ONH appearance and visual acuity at age 10 years.

“These findings underscore the need for long-term glaucoma surveillance among infant cataract surgery patients. They also provide some measure of assurance that it is not necessary to place an intraocular lens at the time of cataract surgery," said Michael F. Chiang, MD, director of the National Eye Institute.

Multivariate analyses showed that younger patient age at the time of surgery is the strongest and only independent risk factor for glaucoma, 10 years after surgery. In addition, “For development of any glaucoma-related adverse event at 10 years, small corneal diameter at surgery, closely related to age at surgery, emerged as the only risk factor.”

Because children who underwent surgery earlier vs later exhibited better median visual acuity, researchers cautioned that the desire to achieve maximum visual acuity must be counterbalanced against an increased risk of glaucoma in infants with a unilateral congenital cataract.

A relatively small sample size, lack of study-required follow-up between 5 and 10 years, and lack of study-related treatment protocols mark limitations to the study.

“Lifelong surveillance for the development of glaucoma-related adverse events remains important, with the hope that early diagnosis and treatment may facilitate preservation of ONH health and maximal visual function,” the authors concluded.

Reference

Freedman SF, Beck AD, Nizam A, et al. Glaucoma-related adverse events at 10 years in the infant aphakia treatment study: a secondary analysis of a randomized clinical trial. JAMA Ophthalmol. Published online December 17, 2020. doi:10.1001/jamaophthalmol.2020.5664