Transscleral freezing of the retina: an experimental study.

Transscleral freezing of the dogs retina for 2 seconds icas done experimentally and demonstrated ophthalmoscopically and histologically. The residling lesion was studied from the instant of freezing to the stage of final healing. Attempts were made to alter the lesion by methods known to affect the freezing of live tissue. The Cooper-Linde cryoprobe was used to produce the lesions. Retinal freezing occurred when the temperature of the probe tip was between -30 and -40° C. Adhesive chorioretinitis involving sclera was observed, first evident in 4 days, and healed in 7 days. The lesion was resistant to retinal separation and without hemorrhage. The conjunctiva appeared unaffected. Retinal destruction increased with increased duration of freezing up to 20 seconds, with little further damage thereafter. Decreasing the temperature of the probe tip to -60° C. for 2 seconds caused a marked increase in retinal destruction, but little change with longer durations at that temperature. Refreezing increased retinal destruction slightly and choroidal reaction markedly. Rapid thawing and subconjunctival injection of glycerol had no effect.