A theoretical model for predicting interfacial relationships of retinal tamponades

Purpose. To establish a theoretical model to determine the relationship between retinal coverage and tamponade shape in relation to tamponade volume, for a variety of tamponades, and to test these relationships with a physical analogue of the human eye. Methods. The theoretical model was based on a static balance between buoyancy forces and surface tension forces, for an axisymmetrically shaped bubble or droplet. In the laboratory experiments, two hemispheres were cut into an acrylic block. The acrylic was soaked with bovine serum for 10 minutes to ensure that the wetting properties were similar to the human retina. Photographic images of various fractions of lighter-than-water (gas, silicone) and heavier-than-water (Oxane HD) tamponades were analyzed by using algorithms written in commercial image-processing software and compared with the theoretical predictions and published data. Results. The theoretical predictions of tamponade shape and retinal coverage agree closely with the results obtained from the analogue experiments. Conclusions. The theoretical model was validated against measurements in a human eye analogue and published data. The three key parameters that characterize the retinal coverage of any given tamponade are the bond number, the contact angle of the tamponade, and the volume used. The model may be used to predict the static properties of new tamponades without in vivo tests.