Near infrared ex-vivo bovine and computer model thresholds for laser-induced retinal damage

Abstract

AbstractThresholds for thermal damage of the retina were determined with excised bovine eyes and a computer model for 1090 nm laser radiation in the applicable pulse duration regime and for varying retinal laser spot diameters. The thresholds compare well with available rhesus monkey data, further validating the models for absolute threshold predictions and parameter studies including in the near infrared (NIR) range up to about 1340 nm. The variation of the spot size dependence for different pulse durations that was found in an earlier study for the wavelength of 532 nm was confirmed, which supports the proposed amendment of ICNIRP, ANSI and IEC laser and incoherent optical radiation exposure limits. The earlier conclusion that the damage mechanism at threshold determined 24 h and 1 h after exposure for the non-human primate (NHP) model is retinal pigment epithelium (RPE) cell damage and not thermal coagulation of the sensory retina was confirmed. The data in the NIR range indicate that scattering within the RPE and choroid does not significantly enlarge the effective spot size, and that the rhesus monkey minimal spot