Proposed changes for the retinal thermal MPE

Recent in-vitro, computer model and non-human primate threshold data provide for a more complete set of information of the dependence of the retinal thermal damage threshold values on retinal irradiance profile diameter for the complete range of relevant pulse durations. Based on this data it would be possible to reduce the unnecessarily large safety factor by increasing the current laser and broadband exposure limits for extended sources for pulsed durations up to the millisecond range. A pulse duration dependent parameter α_max is proposed which equals 100 mrad only for longer pulses and decreases to 5 mrad for shorter pulses. At the same time, for nanosecond pulses, the exposure limits need to be lowered, as in that pulse duration regime, microcavity formation around melanosomes results in a lower damage threshold than would be expected in the thermal confinement regime.