Long-term functional outcomes of different subtypes of primary congenital glaucoma

Aim To analyse long-term visual outcomes across different subtypes of primary congenital glaucoma (PCG). Methods Patients with PCG with a minimum of 5-year follow-up post surgery were included in the study. Snellen visual acuity recordings taken at their last follow-up were analysed. We evaluated the results using Kaplan-Meier curves to predict the probability of maintaining good vision (as defined by a visual acuity of 6/18 or better) in our patients after 30-year follow-up. The results were also analysed to determine whether there were any differences in the long-term visual acuities with time between the neonatal and infantile PCG. We also analysed the reasons for poor visual outcomes. Results We assessed a cohort of 140 patients with PCG (235 eyes) with an average follow-up of 127 +/- 62.8 months (range 60-400 months). Overall, the proportion of eyes with good visual acuity was 89 (37.9%), those with fair visual acuity between 6/60 and 6/18 was 41 (17.4%), and those with poor visual acuity (<= 6/60) was 105 (44.7%). We found a significant difference (p=0.047) between neonatal and infantile patients with PCG whereby the neonatal cohort fared worse off in terms of visual morbidity. On Kaplan-Meier analysis, the cumulative probability of survival of a visual acuity of 6/18 or better was more among the infantile PCG in comparison to the neonatal PCG (p=0.039) eyes, and more among the bilateral than the unilateral affected eyes (p=0.029). Amblyopia was the most important cause for poor visual acuity as shown on a Cox proportional-hazards regression model. Conclusions Long-term visual outcomes of infantile are better than neonatal PCG. Eyes with unilateral have worse visual outcomes compared with those with bilateral PCG because of the development of dense amblyopia.