525 nm Laser Induces Dose-Dependent Retinal Injury in Rabbits, from Transient Suppression to Irreversible Damage

Understanding the precise mechanisms and thresholds of laser-induced retinal injury is critical for both occupational safety and therapeutic applications. While low-level light therapy shows promise for retinal regeneration, high-power laser exposure poses significant risks, potentially leading to photoreceptor damage and retinal detachment. Current safety standards often rely on broad classifications, but specific wavelength effects, like those of 525 nm green lasers, require detailed characterization to inform protective measures and improve clinical management of laser-induced ocular trauma. This study addresses the gap in multimodal assessment of such injuries.

Researchers exposed 24 rabbits to single-eye 525 nm laser irradiation for 0.25 seconds at varying power densities: 0.5, 200, 500, and 1000 mW/cm2. Multimodal evaluations were performed to characterize laser-induced injury. These included functional assessments via electroretinography (ERG), structural imaging using optical coherence tomography (OCT) and OCT angiography (OCTA), histopathology for cellular damage, and aqueous humor cytokine microarray analysis to assess inflammatory and vascular responses.

No visible functional or pathological damage was observed after low-power laser radiation (0.5 mW/cm2). However, laser irradiation exceeding 200 mW/cm2 induced transient electroretinographic suppression and persistent laser spots in the fundus. Retinal edema and hemorrhage were naturally absorbed within 7 days post-injury, but cellular damage and structural changes persisted as old plaques by 14 days. Higher power densities caused more severe and lasting damage. > 1000 mW/cm2 laser exposure caused severe retinal detachment within 1 day, ultimately leading to a retinal hole by 14 days. While overall inflammatory array clustering showed no significant difference, several individual cytokines exhibited statistically significant changes: ANG-1 was upregulated at 500 and 1000 mW/cm2 (p < 0.01), while VEGF-A was downregulated at 500 mW/cm2 (p < 0.05). MIP-1β significantly increased at 200 mW/cm2 (p < 0.05), whereas IL-1RA decreased at 500 mW/cm2 (p < 0.05).