Severity of visual field defects in primary congenital glaucoma and their risk factors

Purpose The primary objective of the study was to assess the frequency and severity of visual field defects (VFD) in primary congenital glaucoma (PCG). The secondary objective was to ascertain any associated risk factors. Methods An ambispective review of patients with PCG on follow-up with a ‘target’ intraocular pressure (IOP) of ≤ 15 mmHg. Age, sex, laterality, duration of follow-up, baseline IOP, baseline cup-disc ratio (CDR), central corneal thickness (CCT), age during filtering surgery, second surgery if any, yearly IOP, glaucoma medications and best corrected visual acuity from 2013 (year 1) to the final review and final CDR were noted down. Children ≥ 5 years of age with best corrected visual acuity ≥ 6/60 were subjected to manual kinetic Goldmann perimetry, and visual field defects (VFD) were identified. Results Seventy-one of 90 eyes completed a reliable kinetic perimetry. The mean age of children was 12.34 ± 4.86 years, and the mean follow-up duration was 10.77 ± 4.69 years. Baseline IOP and CDR were 29.07 ± 8.83 mmHg and 0.66 ± 0.22, respectively. 86.67% of eyes underwent a trabeculotomy + trabeculectomy with mitomycin-C. Thirty-one eyes (34.44%) required a second surgery, 25 of which were bleb revisions and 3 trabeculectomies. Mean IOP and CDR during last visit were 10.23 ± 2.76 mmHg and 0.52 ± 0.25, p < 0.001 as compared with baseline. On Goldmann perimetry, 19 eyes, 26.76%, had defects, arcuate scotoma being most frequent. On the Fisher exact test, a baseline/final CDR > 0.8, undergoing just a trabeculectomy with MMC, needing ≥ 2 glaucoma medications on review or a repeat trabeculectomy was associated with greater severity of VFD. On univariate logistic regression, eyes that needed a bleb revision [OR, 95% CI 9.75 (2.66–35.67), p = 0.001], a repeat trabeculectomy with mitomycin-C [OR (CI) 18 (1.31–245.58), p = 0.03] and final CDR of > 0.8 [OR (CI) 23.1 (3.7–144.21), p = 0.001] were associated with VFD. On multivariable regression analysis, female sex [OR (CI) 18 (2.01–161.04), p = 0.01] was identified as the single most important risk factor for development of a VFD. Conclusion At a ‘target’ IOP of ≤ 15 mmHg, 26.76% of PCG eyes manifested a VFD over 10 years. Baseline and/or final CDR > 0.8, necessity for ≥2 medications or a repeat glaucoma surgery, and female sex were identified as risk factors for development and greater severity of glaucomatous VFD.