Embryoloical basis of RD, Factors that keep retina attached, Mechanism of Detachment, Causes of Exudative RD
Presented as DNB Resident at Sri Sankaradeva Nethralaya, Guwahati
2. Retinal detachment- separation of neurosensory
retina from the retinal pigment epithelium with the
accumulation of fluid in the potential space between
them.
Depending on mechanism of subretinal fluid
accumulation-
5. Normally, these two layers lie in apposition to each other, the potential space between them representing the
original primary optic vesicle.
It is understandable that these two layers can separate from each other and such an event is k/a detachment.
8. Three mechanisms for exudative RD
1.excessive production of fluid, such as from a neoplasm,
2. reduced RPE function, such as from inflammation- Harada disease,
posterior scleritis
3. poor outflow, such as with idiopathic uveal effusion syndrome
9.
10. 1. constant secretion of fluid into the eye by the ciliary body, causing minor changes in
hydrostatic pressure from the center of the eye to the outside.
2. High osmotic pressure in the choroid, when compared with that of the
vitreous, would cause outward movement of water.
3. Also, the retinal pigment epithelium (RPE) is constantly moving ions toward the
choroid with associated movement of water. This causes the tissues lining the eye to
remain in apposition.
11. RPE has a high capacity for water transport
The RPE maintains retinal adherence and absorbs subretinal
fluid by means of
1.active transport
2.creation of an osmotic gradient
3. hydrostatic forces (lesser degree)
12. Exudative retinal detachment-
Vascular, inflammatory and neoplastic diseases of RPE involving retina, RPE and
choroid in which fluid leaks outside vessels and accumulates under the retina.
As long as RPE is able to compensate by pumping the leaking fluid into the
choroidal circulation, RD does not occur.
When the mechanism is overwhelmed or functions subnormally, fluid accumulates
in subretinal space.
13. 1.Neoplasms involving retina, RPE and choroid- such as choroidal melanoma, malignant melanoma, choroidal hemangioma,
and metastatic lesions to the choroid (eg. from breast).
Lifting up retina mechanically and transudation of fluid due to circulatory disturbances caused by the mass of neoplasm
Exudative RD should be considered to be due to intraocular tumour until proved otherwise.
2.Inflammatory- Sympathetic ophthalmia, Vogt Kayanagi Harada syndrome (posterior uveitis), posterior scleritis
3. Vascular
Coat’s disase (congenital vascular malformation), Angiomatosis retinae- excessive production of subretinal fluid and exudates
Malignant hypertension, toxaemia of pregnancy (ischemia of retina causing RPE dysfunction)
Subretinal neovascular membranes- ocular histoplasmosis, age related macular degeneration (ARMD)
Choroidal neovascularisation may leak and give rise to extensive accumulation of fluid at posterior pole
4. Idiopathic- Uveal effusion syndrome (thickening of sclera)
15. In conditions such as central serous chorioretinopathy (idiopathic central serous choroidopathy), the
metabolic
activity of the RPE can be diffusely compromised and subretinal fluid is presumably less effectively
absorbed.
Hyperpermeability of choroidal vessels as demonstrated by indocyanine green angiography are also
seen as part of the disease process.
Exudative retinal detachments can occur when steroids (exogenous, hypercortisolism) are used in
the setting of central serous chorioretinopathy.
16.
17. Idiopathic uveal effusion can produce a serous retinal detachment along with a similar detachment of
the choroid, possibly resulting from impaired choroidal venous outflow.
Associated with nanophthalmos (mean axial length 16 mm) or high hyperopia (mean +16 diopters)
with abnormally thick sclera (disorganization of collagen fiber bundles and deposits of proteoglycans
in the scleral matrix.
Abnormally thick sclera compresses the vortex veins and impedes venous drainage.
Further support for this concept is derived from the observation that decompression of the vortex
veins may cause the effusion to resolve.
