Geometric Changes of the Eye with an Encircling Scleral Buckle

Abstract

Abstract: : Purpose: To investigate the postoperative changes and the mechanism of retinal reattachment after an encircling scleral buckle, the geometric changes of the eye with an encircling scleral buckle was analyzed using a simplified eye model and enucleated porcine eyeball. Methods: The simplified eye model is an inelastic sphere with an external diameter of 25 mm and an internal diameter of 23.6 millimeters. With an encircling scleral buckle, it was assumed that the circumference of the eyeball would decrease, and in particular with tightening of the buckle, the cross-section of eyeball would be deformed to an ellipsoid shape. The changes in radius, internal surface area, and volume of the eyeball in relationship to the changes in height and span of the silicone buckle were calculated. Ex vivio experiments were done with enucleated procine eyeball. The difference of axial length and volume displacement were measured and compared to the theoretical data. Results: The radius of eyeball decreased by 0.19-0.90 mm with an encircling scleral buckle, and varied according to the increment of the tightening of the encircling band. The axial length of the eye increased and the volume of the eye decreased also with increased tightening of the band. The scleral arc of the buckle was shorter than the retinal arc of the buckle by 0.09-0.55 mm and the scleral surface area of the buckle was smaller than the retinal area of the buckle by 56-219 mm²; therefore the retina would be redundant. Ex vivo experiment showed that the predicted change of axial length and volumn by the model fitted well with the actual change of them. Conclusions: An encircling scleral buckle changes the axial length and decreases the volume and internal surface area of the eye, making the retina redundant. This redundancy helps resolve or alleviate the problem of a foreshortened retina in retinal reattachment procedures.

Keywords: retinal detachment • anatomy • animal model