Anytime subretinal fluid accumulates in the space between the neurosensory retina and the underlying retinal pigment epithelium (RPE), a retinal detachment occurs. Depending on the mechanism of subretinal fluid accumulation, retinal detachments traditionally have been classified into rhegmatogenous, tractional, and exudative.
Under normal conditions, water flows from the vitreous cavity to the choroid. The direction of flow is influenced by the relative hyperosmolarity of the choroid with respect to the vitreous and the RPE that actively pumps ions and water from the vitreous into the choroid. When there is an increase in the inflow of fluid or a decrease in the outflow of fluid from the vitreous cavity that overwhelms the normal compensatory mechanisms, fluid accumulates in the subretinal space leading to an exudative retinal detachment.
The composition of the choroidal interstitial fluid plays a fundamental role in the pathogenesis of an exudative retinal detachment. The composition of the choroidal interstitial fluid in turn is influenced by the degree of choroidal vascular permeability. Any pathological process that affects choroidal vascular permeability can potentially cause an exudative retinal detachment. Alternatively, damage to the RPE prevents the pumping action of fluid and can lead to fluid accumulation in the subretinal space. Several inflammatory, infectious, vascular, degenerative, malignant, or genetically determined pathological conditions have been recognized to cause exudative retinal detachments.
In preeclampsia, there is intense vasoconstriction of the choroidal arterioles, which leads to choroidal ischemia and RPE infarction. The outer blood-retinal barrier is broken down and causes increased vascular permeability.
Eyes with Coats disease exhibit vascular endothelial growth factor (VEGF) and VEGF receptors. Nine enucleated eyes with Coats disease were analyzed, and immunoreactivity for VEGF and vascular endothelial growth factor receptor 2 (VEGFR-2) was detected in macrophages and endothelia of abnormal vessels. 
Given the diverse nature of the underlying causes of exudative retinal detachments, no reports are available on the frequency of this condition.
Mortality and morbidity depend on the underlying cause. For instance, a patient with an exudative retinal detachment from scleritis secondary to rheumatoid arthritis has a severe condition. Compare this to a healthy patient who underwent scleral buckling surgery with an exudative retinal detachment. The outlooks are very different in each case.
Exudative retinal detachment secondary to preeclampsia usually resolves without long-term complications. After delivery, the subretinal fluid is absorbed by the RPE pump and the visual acuity returns to pre-detachment levels in a few weeks. However, patients with severe eclampsia may experience permanent visual loss secondary to extensive RPE necrosis even when the retinal detachment resolves.
Racial predilection depends on the underlying cause, to include the following:
Vogt-Koyanagi-Harada syndrome appears to be more common in Asians and Hispanics than in Caucasians.
Choroidal melanoma is more common in Caucasians than in other races.
Exudative age-related macular degeneration is more common in Caucasians than in other races.
Sex predilection depends on the underlying cause, to include the following:
Coats disease is more common in males than in females.
The uveal effusion syndrome is more common in males than in females.
Idiopathic central serous chorioretinopathy occurs more commonly in men than in women.
Age predilection depends on the underlying cause, to include the following:
Coats disease is more common in children and young adults.
Exudative age-related macular degeneration is a condition of elderly persons.
Idiopathic central serous retinopathy occurs most often in middle-aged people.
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