Abstract
Purpose: :
To determine if freezing temperatures are transmitted to the sclera across silicone explants, and to objectively measure and compare the magnitude of temperature-lowering effect by cryopexy across various silicone explants.
Methods: :
Human cadaveric sclera fixed in ethanol are subjected to therapeutic freezing temperatures used in cryopexy treatment in the management of retinal detachment. The sclera are either directly exposed to the cryoprobe, or with various silicone explants placed between the cryoprobe and the bare sclera in room temperature. The temperature on the opposite side of the sclera is objectively recorded using metal probe connected to a digital thermometer (EXTECH Instruments Dual Input Datalogging Thermometer). Recordings were recorded several times for each experiment and the mean readings are analysed and compared.
Results: :
The lowest temperature recorded in cryopexy across the bare sclera did not reach as low as -76°F as commonly thought, but only half of the working temperature at -29°F±5°F. Silicone buckle with or without encircling bands are able to transmit freezing temperatures across the sclera. However, silicone sponge has the lowest ability to transmit freezing temperatures in trans-scleral cryopexy, recording a lowest temperature of only 41°F±6°F.
Conclusions: :
Cryopexy and scleral buckle are standard methods of treating retinal detachment by different modes of actions. It is standard practice to apply cryopexy to cause retinal adhesion before the use of silicone scleral buckle to reduce vitreo-retinal traction, as silicone is known to be heat insulators. However, we have shown that freezing temperatures can be transmitted to the sclera across various silicone explants, which may create sufficient localized inflammation to cause retinal adhesions. This may prove to be therapeutically beneficial in sealing a break in the retina and provide a new perspective in the management of retinal detachment.
Keywords: retina • retinal detachment