Three degrees of scleral damage were observed when heating sclera in physiological saline: formation of vacuoles at 50 C, fragmentation of collagen bundles at 59 C, and denaturation of collagen at 65 C. The same degrees of damage were found after diathermy applications. The gradient of temperatures indicated by the silver-stained cryosections demonstrates the pathway of the electric current through sclera. A point electrode produces high temperatures at the point of contact with sclera. With a flat electrode, the electric current flows along the periphery of the metallic electrode and scleral damage is more prominent along the edges of the electrode. Scleral damage can be decreased with a cuff of saline solution around the electrode.
deGuillebon HF, Ishii Y. Scleral Changes During Diathermy ApplicationInfluence of Electrode Type. Arch Ophthalmol. 1970;83(6):752-759. doi:10.1001/archopht.1970.00990030752015