Total internal reflection of laser light in eyes filled with silicone oil

BACKGROUND AND OBJECTIVES: This is the first report of clinical settings in which total internal reflection of laser light in eyes filled with silicon e oil was observed. The authors analyze this phenomenon and outline the pot ential hazards it may present to patient, surgeon, and operating room perso nnel. MATERIALS AND METHODS: The authors observed significant reflection of laser light off the silicone-water interface both intraoperatively and in the cl inic. The critical angle according to Snell's law (i.e., the angle at which total internal reflection occurs at the interface between silicone oil and vitreous) was calculated. The critical angle was found to be 71.9691 degre es ( 72 degrees). RESULTS: An analysis of each of the clinical conditions where this phenomen on was observed is presented. Clinical and surgical implications are discus sed. ii CONCLUSIONS: The hazard of total internal reflection of laser light in eyes filled with silicone oil should be recognized by ophthalmologists to avoid possible complications. Techniques for overcoming and circumventing the di fficulties resulting from this phenomenon are proposed.