MELANIN GRANULE MODEL FOR LASER-INDUCED THERMAL-DAMAGE IN THE RETINA

An analytical model for thermal damage of retinal tissue due to absorp tion of laser energy by finite-sized melanin granules is developed. Si nce melanin is the primary absorber of visible and near-IR light in th e skin and in the retina, bulk heating of tissue can be determined by superposition of individual melanin granule effects. Granules are mode led as absorbing spheres surrounded by an infinite medium of water. An alytical solutions to the heat equation result in computations that ar e quick and accurate. Moreover, the model does not rely on symmetric b eam profiles, and so arbitrary images can be studied. The important co ntribution of this model is to provide a more accurate biological desc ription of submillisecond pulse exposures than previous retinal models , while achieving agreement for longer pulses. This model can also be naturally extended into the sub-microsecond domain by including vapori zation as a damage mechanism. It therefore represents the beginning of a model which can be applied across the entire pulse duration domain.