Does laser delivery mode matter? Corneal sensitivity and ocular surface changes after single-spot and multispot PRP in proliferative diabetic retinopathy

Panretinal photocoagulation (PRP) is the standard treatment for proliferative diabetic retinopathy (PDR), but it may alter corneal sensitivity and tear film stability through thermal and neuroinflammatory mechanisms. The recent introduction of pattern-scanning multispot systems allows shorter pulse durations and lower cumulative energy delivery. This study aimed to evaluate pre- and post-treatment changes in corneal sensitivity and ocular surface parameters following single-spot and multispot PRP in patients with PDR. This retrospective observational study included 90 eyes from 45 patients with type 2 diabetes mellitus who underwent PRP using either single-spot (n = 44) or multispot (n = 46) techniques. Corneal sensitivity (Cochet–Bonnet esthesiometer), tear breakup time (TBUT), Schirmer I test, and corneal fluorescein staining (Oxford scale) were measured at baseline, and at 1 and 3 months after PRP. Repeated measures were analyzed using generalized estimating equations to account for inter-eye correlation, and multivariate analysis was performed to adjust for potential confounding factors. In the single-spot PRP group, TBUT, Schirmer, and esthesiometry values significantly decreased at both 1 and 3 months compared with baseline (p < 0.05), while Oxford grading scores increased significantly (p < 0.05). In the multispot PRP group, TBUT values decreased at 1 month but showed no significant difference from baseline at 3 months, and esthesiometry values increased significantly at 3 months (p < 0.05). Total delivered energy was lower in the multispot group despite a higher number of laser burns (p < 0.001). Diabetes duration was independently associated with Schirmer test values at month 1 and Oxford grading scores at month 3 (p < 0.05). Both PRP techniques effectively treated PDR, but their effects on ocular surface parameters differed. Single-spot PRP resulted in a sustained reduction in corneal sensitivity and tear film stability, whereas changes after multispot PRP were transient and less pronounced. The multispot technique, characterized by shorter pulses and reduced cumulative energy, may therefore minimize anterior segment alterations associated with PRP.