Deriving irradiation control parameters for laser photocoagulation on the retina

Laser photocoagulation is used extensively by ophthalmologists to treat retinal disorders such as diabetic retinopathy and retinal breaks. Currently, the procedure is performed manually and suffers from several drawbacks that a computer-assisted system could help alleviate. Such a system is under development that will rapidly and safely place multiple therapeutic lesions at desired locations on the retina in a matter of seconds. This system provides real-time, motion-stabilized lesion placement for typical clinical irradiation times (100 ms). When performing laser photocoagulation on the retina, the dynamic reflectance of the lesion formed by the laser may be used as a control signal. Using digital filtering and estimation techniques on the sampled reflectance signal, the latency time and growth rate are determined. These parameters are used to derive a control signal for the irradiation time of the laser. The goal is to optimize the therapeutic effect, without overexposing the tissue. The result is consistent lesion formation over any part of the retina.