Motility and binocular function after radial episcleral buckle

Abstract

The incidence of motility disturbances induced by episkleral buckle operations for retinal detachment has been reported to range between 7 and 77%. We anticipated a relation between the buckle size and the incidence and extent of motility disturbances. We examined 45 patients 2 to 4 years after successful retinal detachment surgery with a radial buckle. The buckle diameter was 3-11 mm. Patients were examined for diplopia and heterophoria in the primary position and in 20 degrees secondary and tertiary gaze deviations. Stereopsis was determined using the TNO plates. Refractive error and visual acuity were also measured. Heterophoria measurements in the various directions of gaze revealed a hypermotility in 22/45 cases. A hypomotility was encountered only in one of the 45 cases. In 40 of the 45 cases the field of binocular single vision had a radius of at least 20 degrees. 39 of the 45 patients had stereopsis (after macular detachment 17/22, without macular detachment 22/23). 7/32 patients with a buckle of > or = 5 mm reported on diplopia, but none of the 13 patients with a buckle of < or = 4 mm. Heterotropia in the primary position was found in one of the 45 cases. He had three buckles, a 10.5 mm buckle under the superior rectus muscle of one eye and a 4 and 7.5 mm buckle under the inferior oblique and rectus muscles of the other eye. The resulting vertical deviation was successfully treated with prisms. Motility disturbances in the upper field of gaze were found in 2 of 45 cases with buckles of 5 and 7.5 mm. Diplopia was not permanent in these cases. Hypermotility towards the position of the buckle may be explained by a deviation of the adjacent rectus muscles, after sharp preparation and shrinkage of the intermuscular septum. Since motility disturbances were encountered only with buckles of > or = 5 mm, small buckles (< or = 4 mm) should be applied whenever possible.