Early-Onset Normal-Tension Glaucoma in Patients Under 40 Years of Age: Risk Factors for Progression

Purpose: To investigate the clinical characteristics of normal-tension glaucoma (NTG) in patients under 40 years of age, aiming to identify distinct patterns and risk factors associated with progression in early-onset NTG. Methods: A retrospective study was conducted on NTG patients under 40 years of age seen at a tertiary eye care center from 2006 to 2023. Details that were retrieved included visual field indices, intraocular pressure at baseline, central corneal thickness, refractive error, optical coherence tomography (OCT) & OCT angiography (OCT-A) parameters, ocular and systemic associations, and visual field progression on glaucoma progression analysis. Data were statistically analyzed using multivariate regression for predictors of progression. Results: A total of 41 eyes from 26 NTG patients under 40 years (mean age = 32 ± 5.1 years; 22.5% female) were studied. Twelve had bilateral NTG, while 14 were unilateral (seven showing pre-perimetric changes and seven being normal or disc suspects). Affected eyes had significantly worse mean deviation (MD) (-10 ± 8.1 dB) and visual field index (VFI) (78 ± 25.9%) compared to unaffected eyes (-1 ± 1.1 dB and 92 ± 7.8%, p = 0.02). Low-to-moderate myopia was observed in 72%, while high myopia (>6 dioptres) was present in six eyes (three patients). Progression occurred in nine eyes (rate of progression = -3 ± 1.9 dB, including five eyes with high myopia), with high myopia and reduced macular VD being significant predictors (β = -0.6, p = 0.03; β = 0.3, p = 0.002). Conclusion: NTG in individuals under 40 years of age is characterized by significant changes in macular vessel density. High myopia and reduced macular vessel density on OCT-A may be risk factors for the progression of NTG in young patients.