Anomalous reflectance of laser-induced retinal lesions

We investigated anomalies in the reflectance change of retinal lesions resulting from laser photocoagulation. These anomalies deviate from the predicted pattern and could cause misleading postoperative assessment of lesion depth and problems with proposed automated lesion control algorithms. We found that for certain irradiation parameters which produce super-threshold lesions, lesions exhibiting annular reflectance patterns are induced in an albumen eye phantom. The correlation between central reflectance and actual lesion depth thus becomes invalid for these anomalous lesions. Evidence of anomalous lesions in vivo was also found. Assumptions regarding retinal lesion formation must consider annular reflectance patterns. These patterns are produced by vaporization in the albumen eye phantom; vaporization may also play a role in anomalous retinal lesions along with the well known effect of minor retinal hemorrhage.