Simulation of laser induced retinal thermal injuries for non-uniform irradiance profiles and their evaluation according to the laser safety standard

TL;DR

This paper presents a computer model to simulate laser-induced retinal thermal injuries considering non-uniform irradiance profiles, comparing injury thresholds with safety standards to improve laser safety evaluations.

Contribution

The study introduces a novel computer simulation approach that predicts retinal injury thresholds without averaging irradiance profiles, enhancing laser safety assessment accuracy.

Findings

The model predicts injury thresholds for various non-uniform irradiance profiles.

Comparison shows differences between model predictions and safety standard classifications.

The approach improves understanding of laser safety limits for complex irradiance patterns.

Abstract

Laser systems emitting radiation in the visible and near infrared region are potentially hazardous for the retina of the human eye. This can result in irreparable injuries due to photomechanical, photothermal or photochemical light-tissue interactions. This investigation focuses on the photothermal interaction for which a computer model is used to simulate the thermal behavior of the retina and to predict the injury threshold values. The most important factors are the wavelength of the radiation, the exposure time and the irradiance profile on the retina. For performing safety evaluations and classifications the laser safety standard IEC 60825-1:2014 has to be considered. These evaluations are based on emission limits which depend on the same above mentioned factors. According to the IEC 60825-1:2014, non-uniform retinal images are treated by an image analysis where an averaged spot size is used. This averaged size is calculated by the extent of the irradiance profile along two orthogonal directions. Unlike the laser safety standard, the computer model predicts the injury thresholds for an irradiance profile on the retina without averaging the spot size. In this investigation, a broad variety of non-uniform retinal images is investigated with regard to the injury thresholds predicted by the computer model and to the classifications according to the laser safety standard.