Giant Retinal Tears

Giant retinal tear (GRT) is defined as peripheral break extending through 900 or more of the retinal circumference in which the vitreous gel is attached essentially to the anterior flap thereby allowing independent mobility of the posterior edge of tear. GRT needs to be differentiated from Giant dialysis, which is retinal disinsertion from the ora serrata with 90 degrees or more of circumferential extent. These conditions differ markedly in their vitreoretinal relationships and prognosis. In dialysis vitreous bridges the dialysis gap and is attached to the posterior margin of the dialysis and posterior vitreous detachment is absent thus preventing it from inversion. Conversely in giant tear vitreous remains strongly attached to the anterior margin of the tear and the posterior flap, without any vitreous adhesion is free to move and inverts towards disc due to gravity. Dialysis is generally amenable to buckling where as giant tear requires highly specialized techniques especially for unfolding the inverted retinal flap. Schepens described three types of giant retinal tears: Idiopathic seen in 70%, traumatic in 20% and in 10% at the posterior edge of chorioretinal degeneration (1). Giant retinal tears (idiopathic or traumatic) occur more frequently in males. Myopia was a frequent finding, with approximately 40% of eyes in this series having more than 8 diopters of myopia. Fellow eyes of patients with giant tear are at considerable risk of retinal breaks, giant tears and retinal detachment. In a study of 226 patients with giant tears, 51 % developed retinal tears in the fellow eye including 13% who developed Giant tears (2). The pathogenesis of idiopathic GRT is a liquefying process of the central gel forming a cavity while there is relentlessly progressive shrinkage of the remaining gel in. the vitreous base exerting traction on the base and the peripheral retina causing GRT. Posterior flap folds because it is not sustained by intact vitreous face. Radial extensions may occur generally at either end of the tear and if large in size may present difficulties in surgical repair.