Ocular structural remodeling and optic nerve damage in primary congenital glaucoma: findings from a vietnamese tertiary cohort.

BACKGROUND: To characterize the clinical and ocular structural features of primary congenital glaucoma (PCG) and to identify factors associated with optic nerve damage in a Vietnamese tertiary referral cohort. METHODS: In this cross-sectional study, 48 patients with PCG (85 affected eyes) examined at the Vietnam National Eye Hospital between 2022 and 2025 were included. Clinical, biometric, and ultrasound biomicroscopy (UBM) parameters were analyzed at both patient and eye levels. Descriptive comparisons were presented for all affected eyes and fellow healthy eyes, whereas inferential comparisons between affected and fellow healthy eyes were restricted to paired analyses of unilateral cases. Comparisons across C/D-based optic disk cupping categories were performed using patient-clustered generalized estimating equations (GEE) to account for inter-eye correlation. Multivariable GEE linear regression was used to identify factors independently associated with cup-to-disk ratio (C/D). RESULTS: Among 48 patients (median age, 3.0 years), 37 (77.1%) had bilateral disease, leaving 11 patients with unilateral PCG and fellow healthy eyes available for paired comparisons; 37 of 46 evaluable patients (80.4%) were symptomatic at presentation. In paired analyses of these 11 unilateral cases, affected eyes demonstrated significantly larger corneal diameter (12.50 vs 10.50 mm, p = 0.001), longer axial length (25.40 vs 22.30 mm, p = 0.001), more myopic refractive error (-2.00 vs +0.38 D, p = 0.016), and greater C/D ratio (0.45 vs 0.00, p = 0.008) than fellow healthy eyes, whereas RNFL thickness did not differ significantly (p = 0.250); however, this comparison was based on only three paired OCT examinations and should be considered exploratory. UBM revealed wider anterior chamber angles, thinner limbal cornea, reduced iris thickness, longer ciliary processes, and deeper anterior chambers in affected eyes (all p < 0.05). Greater optic disk cupping was associated with more myopic refractive error (GEE p < 0.001), larger corneal diameter (GEE p < 0.001), higher intraocular pressure (GEE p = 0.002), and longer axial length (GEE p < 0.001). In multivariable GEE analysis, both corneal diameter (adjusted B = 0.106, 95% CI 0.025-0.187; p = 0.010) and axial length (adjusted B = 0.046, 95% CI 0.012-0.080; p = 0.008) remained independently associated with C/D ratio. CONCLUSION: Primary congenital glaucoma was associated with substantial structural alterations involving both the anterior and posterior segments of the eye. Among the evaluated structural parameters, axial length demonstrated the most consistent association with optic nerve damage across descriptive, severity-stratified, and multivariable analyses, whereas corneal diameter also remained independently associated after multivariable adjustment. These findings from this cross-sectional cohort suggest that axial elongation and corneal enlargement should be interpreted as structural markers associated with cumulative ocular remodeling and disease severity, rather than causal determinants of glaucomatous optic nerve damage. Longitudinal studies are needed to determine whether serial structural measurements, particularly axial length, can improve monitoring of disease progression in children with PCG.