Maximum permissible exposure of the retina in the human eye in optical coherence tomography systems using a confocal scanning laser ophthalmoscopy platform

When using scanning laser ophthalmoscopy to produce images of the eye fundus, maximum permissible exposure (MPE) limits must be considered. These limits are set out in international standards such as the National Standards Institute ANSI Z136.1 Safe Use of Lasers (USA) and BS EN 60825-1: 1994 (UK) and corresponding Euro norms but these documents do not explicitly consider the case of scanned beams. Our study aims to show how MPE values can be calculated for the specific case of retinal scanning by taking into account an array of parameters, such as wavelength, exposure duration, type of scanning, line rate and field size, and how each set of initial parameters results in MPE values that correspond to thermal or photochemical damage to the retina.