Excised bovine retinas were used as an explant model for threshold determination of laser induced thermal damage for multiple pulse exposures for the laser wavelength of 532 nm. The thresholds as determined by fluorescence viability staining compare very well with the prediction of thermal damage computer model that is based on the Arrhenius damage integral. Comparison of the experimental data with the thermal damage computer model that additivity of multiple pulses can be understood on the basis of partial thermal damage induced by the individual pulses. Both models were previously (BIOS 2006) validated against non-human primate threshold data. The multiple pulse thresholds for a given series of pulses were compared against the MPE evaluation method for multiple pulses, referred to as N^-1/4 or Total on Time (TOT) rule. Variation of the pulse duration, retinal spot size and the spacing between pulses shows that the TOT rule either reflects the damage threshold trend for multiple pulses very well or errs on the conservative side.

Date Published: 26 March 2007
PDF: 8 pages
Proc. SPIE 6426, Ophthalmic Technologies XVII, 642626 (26 March 2007); doi: 10.1117/12.702354

Published in SPIE Proceedings Vol. 6426:
Ophthalmic Technologies XVII
Bruce E. Stuck; Fabrice Manns; Per G. Söderberg; Michael Belkin M.D.; Arthur Ho, Editor(s)