Dynamic reflectometer for control of laser photocoagulation on the retina

In retinal laser photocoagulation, constant exposure parameters do not result in identical lesions. This lack of reproducibility increases the rate of complications from over- or undertreatment and inhibits determination of the optimal treatment endpoints for different retinal disorders. To this end, a feedback-controlled photocoagulator could make retinal photocoagulation a safer, more reproducible, and faster procedure. A dynamic confocal reflectometer was integrated into a slit lamp laser delivery system. Real-time reflectance changes on the retinas of pigmented rabbits were obtained by monitoring the increasing back-scattered light of the coagulating beam during argon laser photocoagulation. Reproducible temporal reflectance patterns were measured that correlated with ophthalmoscopically assessed lesion intensity independent of the exposure parameters, the transparency of the optical media, and the focusing conditions. As a step toward the development of a feedback-controlled photocoagulator, the confocal reflectometer has been proven in animal trials closely resembling clinical practice.