Ocular Biometric Determinants of Intraocular Pressure and Risk Factors for Ocular Hypertension: The Chinese American Eye Study

Precis: Angle width and iris area measured by anterior OCT are increasingly predictive of intraocular pressure and ocular hypertension below parameter-specific angle width cutoffs. Cumulative gonioscopy score is weakly predictive below all score cutoffs. Purpose: To assess ocular biometric determinants of intraocular pressure (IOP) and risk factors for ocular hypertension (OHTN). Methods: CHES participants underwent Goldmann applanation tonometry, gonioscopy, ultrasound A-scan, and anterior segment OCT (AS-OCT) imaging. Biometric data from one eye per participant were used to develop linear and logistic regression models of IOP and OHTN (IOP >21 mm Hg), respectively, below different angle width cutoffs adjusted for central cornea thickness (CCT). Results: 2,360 eyes of 2,360 eligible participants (1,518 female, 842 male) were analyzed. Mean age was 60.2±7.8 years. Multivariable stepwise linear regression models and changepoint analysis showed that below a trabecular iris space area (TISA 750 ) measurement of 0.08 mm 2 , models became increasingly predictive of IOP up to an adjusted R 2 of 0.84. Smaller TISA 750 and iris area (IA) were the only parameters consistently associated ( P ≤0.04) with higher IOP for TISA 750 below 0.20, 0.10, and 0.05 mm 2 . In multivariable models of OHTN (AUC≤0.95), smaller TISA 750 was associated with OHTN for TISA 750 less than 0.20, 0.10, and 0.05 mm 2 ( P ≤0.03) while IA was associated with OHTN for TISA 750 less than 0.05 mm 2 ( P ≤0.03). Cumulative gonioscopy score (sum of gonioscopy grades) was weakly predictive of IOP at all cutoffs (adjusted R 2 ≤0.08). Conclusion: TISA 750 and IA become strongly predictive of IOP when angle width decreases below a TISA 750 cutoff of 0.08 mm 2 . The relationship between cumulative gonioscopy score and IOP is weak below all gonioscopy score cutoffs. AS-OCT measurements could supplement gonioscopy by helping identify individuals at higher risk for elevated IOP from angle closure.