This is the separation of the retina from it’s underlying tissue, the retinal pigment epithelium, usually as a result of fluid from the vitreous cavity entering the potential space between these tissues through a break or hole in the retina. This is known as rhegmatogenous retinal detachment. Much more rarely, fluid can enter this space via the retinal pigment epithelium, which is known as a serous retinal detachment see central serous retinopathy. Another cause of retinal detachment is pulling of the vitreous on the retina which most commonly occurs in patients with diabetic retinopathy and is known as a tractional retinal detachment.
Frequency of retinal detachment
It is thought that the chance of a rhegmatogenous retinal detachment occuring in your lifetime is around 3%. Any age can be affected, but since it usually occurs as a result of posterior vitreous detachment (PVD), the average age of presentation is approximately 60 years. Posterior vitreous detachment occurs as a result of ageing changes in the structure of the vitreous. When associated with flashing lights or an increase in floaters, about 10% of patients will have a break in the retina. By 60, about 40% of the population will have had a PVD and by 80, about 85%.
The symptoms of a posterior vitreous detachment are brief flashes of light and a sudden increase in the number of floaters. PVD’s can occur without symptoms, however, and some studies have shown that about 5% of the population will develop breaks in the retina without ever having had any symptoms from a PVD. In contrast, a retinal detachment will cause a defect in initially peripheral and then central vision (when the macula becomes detached). Some patients describe this as a bubble, curtain or cloud – essentially it is an obstruction to vision.
Causes of retinal detachment
Usually caused by a PVD associated with age, anything that stimulates a PVD is likely to increase the risk of retinal detachment. Cataract surgery can promote a PVD and is therefore associated with an increased risk of retinal detachment. One study found that about 1% of patients developed a retinal detachment within 8 years of cataract surgery, the risk being greater in younger patients with myopia. Myopic eyes often have other retinal abnormalities, such as lattice retinal degeneration and peripheral atrophic retinal holes, which in themselves increase the risk of retinal detachment.
Diagnosis and treatment of retinal detachment
Your pupils need to be dilated and the vitreous and retina examined at the slit-lamp and with an indirect ophthalmoscope by an ophthalmologist. Early treatment before the macula detaches can preserve central visual acuity. If the macula has detached for more than 1 to 3 days, central visual acuity may never recover. Nowadays, treatment requires surgery under either local or general anaesthetic, in which the vitreous is removed from the eye through three tiny incisions (for light illumination, pressure maintenance and for the vitreous cutter). Once the vitreous has been removed (and vitreo-retinal traction relieved), laser is used to “arkweld” the retina to the underlying choroid (this takes 10 days to work) and gas used to keep the retina flat against the choroid until the laser has had time to work. The gas usually stays in the eye for 2 to 3 weeks and will cause the vision to be blurred for this time.