Experimental study on the influence of pupil diameter on laser-induced retinal damage effects

To investigate the impact of pupil diameter on laser-induced retinal damage, this study employed 473 nm and 1064 nm lasers to irradiate the retinas of Chinchilla rabbits, with an exposure duration of 0.1 s. Apertures of 2 and 5 mm were placed in front of the dilated eyes to simulate pupil conditions in bright and dim environments. Five dose groups were set for each of the four exposure conditions. Retinal damage was assessed at 1 and 24 h post-irradiation by fundus photography and optical coherence tomography (OCT), and the retinal damage threshold (ED₅₀) was determined from the damage incidence collected from fundus photographs. Threshold-level retinal lesions presented as grayish-white coagulation spots. For the 473 nm laser, the ED₅₀ values, expressed as total intraocular energy (TIE), were 1.53 and 2.10 mJ for the 2 and 5 mm apertures, respectively, corresponding to corneal radiant exposures of 48.7 and 10.7 mJ/cm². For the 1064 nm laser, the ED₅₀ values were 38.9 and 67.1 mJ for the 2 and 5 mm apertures, respectively, with corresponding corneal radiant exposures of 1239.3 and 341.7 mJ/cm². These findings demonstrate that when evaluated in terms of corneal radiant exposure, the retinal damage threshold is lower for larger pupil diameters; when assessed in terms of TIE, the retinal damage threshold is lower for smaller pupil diameters.