Probabilistic retinal exposure model

Exposure of retinal tissue to a laser source requires two conditions: the person must be exposed to the laser beam and the laser must be in his/her optical field-of-view. The authors have developed a probabilistic model for the second condition. This model is based on random eye movements, known as saccades, about a look direction. This direction is an input to the model and is known either from head orientation or a task. The model calculates the instantaneous probability that the laser is in the optical field-of-view of the retinal tissues of fovea, macula, and retina. Because of saccades, the location of exposure will change several times a second. The duration of laser exposure for the look direction is then used to calculate the probability that the retinal tissue is exposed at least once, based on independent exposures from the saccades. The concepts and equations of the model are presented, along with example calculations from applying the model to a specific exposure scenario. For a given retinal tissue optical field-of-view, the primary contributor to the probability of exposure is the angle between the look direction and the laser.