The retina is a thin layer of light sensitive tissue on the back wall of the eye. The optical system of the eye focuses light on the retina much like light is focused on the film in a camera. The retina translates that focused image into neural impulses and sends them to the brain via the optic nerve. Occasionally, posterior vitreous detachment, injury or trauma to the eye or head may cause a small tear in the retina. The tear allows vitreous fluid to seep through it under the retina, and peel it away like a bubble in wallpaper.
- 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.
- 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 detahment 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.
- 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.
A minority of retinal detachments result from trauma, including blunt blows to the orbit, penetrating trauma, and concussions to the head. A retrospective Indian study of more than 500 cases of rhegmatogenous detachments found that 11% were due to trauma, and that gradual onset was the norm, with over 50% presenting more than one month after the inciting injury.