Anterior Segment Ischemia Secondary to Disinsertion of Extraocular Muscle in an Animal Model

To compare the frequency and severity of anterior segment ischemia (ASI) after disinsertion of 2, 3 and 4 rectus muscles in rabbit eyes, to evaluate the clinical course of the condition without any therapeutic intervention, and to report the histopathological features of affected eyes. This is a prospective experimental study on rabbit eyes. One eye of all rabbits randomly underwent three muscles surgery including disinsertion and myectomy, and in the fellow eye either 2 or 4 rectus muscles were operated. Each eye was examined daily in order to detect the presence of ASI, severity of inflammation and duration of involvement until complete resolution of inflammatory signs. Finally the involved eye and the non-involved eye of the same rabbit were enucleated and studied by a pathologist. The results in each group and subgroups were compared and statistically analyzed. 84 rabbits were operated and examined, in 42 animals one eye underwent three and the fellow eye underwent two rectus muscle surgery; in the other 42 rabbits, one eye underwent three muscles and in the fellow eye four rectus muscles were operated. The incidence of ASI was 4 eyes (9.5%) in two muscle group,26 eyes (31%) in the three muscle group and 21 eyes (50%) in the four muscle group (P=0.001). Inflammation improved spontaneously in all cases of ASI within about two weeks and histopathology study was reported within normal limits in most cases. In all eyes with ASI, the inflammation resolved spontaneously without therapeutic intervention in an almost similar period of time; destruction or loss of the eye was not detected in any case. ASI is a selflimiting complication of strabismus surgery and may be less disastrous than what was thought before.