The Shearing intraocular lens: where does it go and what does it do in the eye?

Seven Shearing lenses were inserted in four dogs that were selected because their ciliary body sulcus diameter was approximately equal to that of humans. These animals were killed at intervals ranging from 4.5 to 11 months and the eyes submitted for histopathology. In all instances, gross examination revealed the lenses to be well tolerated; however in two eyes there was migration of the peripheral loop into the peripheral iris stroma and in one case, ciliary body sulcus necrosis was seen. No vitreous hemorrhage was found in any of the eyes. One intraocular lens was removed before the animal was killed and the eye did not appear to be damaged. This study raises the possibility of ciliary body damage in those eyes in which the lens is slightly displaced so that one loop exerts pressure on the ciliary body. For this reason, we feel that posterior vitreous hemorrhages must be carefully looked for.