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February 1993

Microwave Diathermy of the Retina and Choroid

Author Affiliations

From the Department of Ophthalmology, North Shore University Hospital-Cornell University Medical College, Manhasset, NY (Drs Finger and Svitra); the Departments of Ophthalmology (Dr Finger) and Pathology (Dr McCormick), The New York (NY) Eye and Ear Infirmary; MMTC Inc, Princeton, NJ (Mr Presser); and the Department of Ophthalmology, Cornell University Medical College, New York, NY (Drs Finger and Svitra). Dr Finger has submitted a patent covering the design and use of the device and procedure described in this study. Drs Svitra and McCormick have no proprietary interest in the materials and/or methods described in this study. Mr Presser was and is currently employed by and owns one share of MMTC Inc.

Arch Ophthalmol. 1993;111(2):254-258. doi:10.1001/archopht.1993.01090020108033

• Microwaves were used to induce chorioretinal scar formation in normal rabbit eyes. We have developed a directional 6.8-gigahertz microwave applicator with a rectangular aperture. It was designed to mimic the shape and function of a T-shaped scleral depressor. For treatment, the applicator was placed on the conjunctiva over the sclera. Then, indentation was used to visualize probe placement during indirect ophthalmoscopy. Thermocouple-controlled heating was initiated such that conjunctival temperatures in a range of 51°C to 65°C were induced for 10 seconds per treatment. We found that treatment at temperatures of 51°C or 52°C for 10 seconds produced circular areas of acute retinal whitening. From these microwave-induced lesions, there evolved chorioretinal attenuation with and without evidence of retinal pigment epithelial hyperplasia. No evidence of scleral damage was noted at these thermal doses.