Ans. C: Diabetes Secondatv retinal detachment may be due to the retina being mechanically pulled away from its bed by the contraction of fibrous tissue in the vitreous, tractional detachment, such as occurs in plastic cyclitis, proliferative retinopathy (diabetes) or the retinopathy of the prematurity Predisposing factors for rhegmatogenous detachment (commonest type) of the retina are myopia, previous intraocular surgery such as aphakia or pseudophakia, a family history of retinal detachment, trauma and inflammation Retinal detachment It is a disorder of the eye in which the retina peels away from its underlying layer of suppo tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency. Types 1. Rhegmatogenous retinal detachment A rhegmatogenous retinal detachment occurs due to a break in the retina that allows fluid to pass from the vitreous space into the subretinal space between the sensory retina and the retinal pigment epithelium. Retinal breaks are divided into three types - holes, tears and dialyses. Holes form due to retinal atrophy especially within an area of lattice degeneration. Tears are due to vitreoretinal traction. Dialyses which are very peripheral and circumferential may be either tractional or atrophic, the atrophic form most often occurring as idiopathic dialysis of the young. 2. Exudative, serous, or secondary retinal detachment An exudative retinal detachment occurs due to inflammation, injury or vascular abnormalities that results in fluid accumulating underneath the retina without the presence of a hole, tear, or break. In evaluation of retinal detachment it is critical to exclude exudative detachment as surgery will make the situation worse, not better. Although rare, exudative retinal detachment can be caused by the growth of a tumor on the layers of tissue beneath the retina, namely the choroid. This cancer is called a choroidal melanoma. 3. Tractional retinal detachment A tractional retinal detachment occurs when fibrous or fibrovascular tissue, caused by an injury, inflammation or neovascularization, pulls the sensory retina from the retinal pigment epithelium. Tractional retinal detachments can also occur in patients with proliferative diabetic retinopathy or those with proliferative retinopathy of sickle cell disease. In proliferative retinopathy, abnormal blood vessels (neovascularization) grow within the retina and extend into the vitreous. In advanced disease, the vessels can pull the retina away from the back wall of the eye, leading to tractional retinal detachment. A minority of retinal detachments result from trauma, including blunt blows to the orbit, penetrating trauma, and concussions to the head. Frequency The incidence of retinal detachment in otherwise normal eyes is around 5 new cases in 100,000 persons per year. Retinal detachment is more common in people with severe myopia (above 5-6 diopters), in whom the retina is more thinly stretched. About two-thirds of cases of retinal detachment occur in myopics. Retinal detachment is more frequent after surgery for cataracts. Although retinal detachment usually occurs in just one eye, there is a 15% chance of it developing in the other eye, and this risk increases to 30-35% in patients who have had cataracts extracted from both eyes