Corneal Clouding May Portend Vision Loss in Patients With Congenital Glaucoma

Corneal clouding may help clinicians predict future blindness in pediatric patients who are diagnosed with primary congenital glaucoma (PCG), according to findings published in the American Journal of Ophthalmology. However, the Saudi Arabia-based research team cautions that their findings may not apply to Western populations.

PCG is a significant cause of childhood blindness in the Middle East, according to researchers. Despite timely surgical intervention to control intraocular pressure (IOP), a significant proportion of children with PCG still develop a visual impairment like optic nerve damage, corneal opacities, cataract, or amblyopia.

Several studies show poor visual outcomes in PCG are associated with unilateral disease, multiple surgeries, poor vision at diagnosis, and ocular comorbidities. Factors such as age at initial presentation, sex, and IOP at initial presentation were not proven to impact long-term visual outcomes.

To determine the baseline risk factors associated with eventual blindness in patients with PCG — and possibly enable early identification of those at high risk — researchers conducted a retrospective clinical cohort study using a hospital-based registry of all pediatric patients who presented with a diagnosis of childhood glaucoma between 1995 and 2014. The baseline characteristics of patients with PCG who were blind at the last follow-up visit were compared with those who were not blind. Excluded from the study were those who had a follow-up visit in less than 5 years, those with secondary forms of childhood glaucoma, and any children who went blind due to surgical complications, such as endophthalmitis and suprachoroidal hemorrhage.

The study included 196 children with a mean age of approximately 9.54 months at presentation. After a mean follow-up of 8.49 years, 20 children (10.2%) were blind. Both “blind” and “not blind” groups had similar (P >.05) baseline demographic factors, IOP, horizontal corneal diameter, spherical equivalent, axial length, and corneal thickness, according to researchers. However, the team found that blind children tended to have severe but also more diffuse corneal clouding (5/20 with “diffuse” in the “blind” group compared to 12/176 in the “not blind” group).

More specifically, in the multivariate regression, only the severity of corneal opacification remained significantly associated with the risk of blindness (P <0.001). . In eyes that were blind, nearly 2 out of 3 had grade 3 corneal clouding (12/20=60%). In contrast, the proportion with grade 3 corneal clouding was 6-fold lower (P <.001) in the “non-blind” group (16/176=9.1%).

Researchers note several limitations of their study, including that the proportion of patients who were blind at follow-up was relatively small, so the ability to find a difference between “blind” and “not blind” groups may have been limited. Second, a few patients received initial treatment somewhere before visiting the researchers’ facility, so baseline clinical features are representative of those on referral rather than those at diagnosis. Third, some clinical features are dependent on subjective evaluation. Additionally, investigators didn’t correlate genetic findings with clinical outcomes. Additionally, the findings are specific to the population studied and may not apply to Western populations.

Reference

Alshigari R, Freidl A, Souru C, et al. Risk factors for blindness in children with primary congenital glaucoma–follow-up of a registry cohort. Am J Ophthalmol. Published online December 20, 2020.  doi:10.1016/j.ajo.2020.12.014