Correlation between pupillary light reflex (PLR) amplitude and visual function in primary angle-closure glaucoma: a retrospective clinical study

This study investigated the correlation between pupillary light reflex (PLR) amplitude and visual impairment severity in primary angle-closure glaucoma (PACG). This retrospective case-control study included 35 eyes of 35 PACG patients and 15 eyes of 15 age-/sex-matched controls. Pupillary parameters (photopic/scotopic diameters, PLR amplitude) were measured using the OPD-Scan III wavefront aberrometer. Clinical metrics included best-corrected visual acuity (BCVA), the cup-to-disc ratio (C/D), the visual field mean deviation (MD), and retinal nerve fiber layer thickness (RNFLT) across six optic disc quadrants. Patients were stratified into mild (MD ≥ -6 dB), moderate (-12 dB ≤ MD < -6 dB), and severe (MD < -12 dB) subgroups per HPA criteria. Compared to controls, PACG patients showed significantly reduced PLR amplitude and scotopic diameter (P < 0.001 and P = 0.013, respectively). Significant inter-subgroup differences were observed in PLR amplitude (mild vs. severe; moderate vs. severe) (all P < 0.001). Significant inter-subgroup differences were observed in MD (mild vs. severe: P < 0.001; moderate vs. mild: P = 0.010;moderate vs. severe: P = 0.032), BCVA (mild vs. severe: P = 0.005), C/D (mild vs. severe: P < 0.001; moderate vs. severe: P = 0.013), and average RNFLT (mild vs. severe: P < 0.001; moderate vs. severe: P = 0.032). PLR amplitude negatively correlated with C/D (r=-0.706, P < 0.001) and positively with MD (r = 0.746), nasal (r = 0.527), superonasal (r = 0.449), inferonasal (r = 0.513),Temporal(r = 0.475)inferotemporal(r = 0.483),and average RNFLT (r = 0.526) (all P < 0.05). Multivariable linear regression analysis revealed that only MD was independently associated with PLR amplitude (β = 0.040, P < 0.001) after adjusting for age, IOP, BCVA, ACD, and IT750. Reduced PLR amplitude in PACG correlates with structural and functional deterioration, reflecting disease severity. As a rapid, non-invasive metric, PLR assessment complements conventional methods for objective PACG evaluation.