[Measurement of the sealing impression during the cerclage operation]

In hypotensive or hypertensive eyes (i.e., in the treatment of perforating injuries), choosing an ideal length for the plaque is often difficult. The goal of the procedure is to achieve a sufficient depth of the impression. However, excessive depth must be avoided, since this could lead to String syndrome and scleral necrosis. On the basis of an analysis of ocular geometry it proved possible to calculate the circumference of the globe in the region of the cerclage, and from this the ideal length of the plaque. When silicone foam plaques are used it is between 70.4 mm when attached close to the muscle insertion and a maximum of 74.1 mm when placed on the equator of the bulb. Basing surgery on this calculation method in more than 300 patients, no complications such as String syndrome, scleral necrosis or secondary glaucoma were observed. A chronic inflammatory reaction to the scleral buckle was seen in three cases. In order to avoid this complication, caused by the enormous volume of the cylindrical silicone plaque, splitting or flattening of the plaque is recommended.