Fundus: Retinal Detachment Flashcards
What is retinal detachment?
It is a cleavage in the plane between the neurosensory retina and the RPE (thus ‘creating’ a subretinal space).
How many layers does the retina comprise? Name them.
Two layers:
- Neurosensory retina (including the photoreceptors and the ganglion cell layer)
- The retinal pigment epithelium (RPE).
What is retinal detachment with and without a retinal break called? Which is more common?
Rhegmatogenous and non-rhegmatogenous respectively.
Most cases of retinal detachment are rhegmatogenous.
Describe rhegmatogenous retinal detachment.
The retinal detachment is caused by a tear or a hole in the neurosensory retina, which allows fluid from the vitreous humour to pass through into the subretinal space.
Degenerative changes in the vitreous are important in the pathogenesis of rhegmatogenous retinal detachment.
What are two types of non-rhegmatogenous retinal detachment?
- Tractional: where the retina is pulled off by membranes growing across its surface (eg. advanced diabetic eye disease)
- Exudative: caused by a breakdown of the blood-retinal barrier, allowing fluid to accumulate in the subretinal space.
What is the structure of the vitreous?
It is a gel consisting of water and glycosaminoglycans. It is structured, having a central body and a peripheral cortex. The cortex coats the retinal surface and, in places, is firmly attached to the retina.
As part of the normal ageing process of the eye, the vitreous loses its gel structure and peels away from the retina (posterior vitreous detachment). Traction on the retina may then create a tear.
This is more common in high myopes and following ocular trauma (blunt or perforating).
What are the symptoms of posterior vitreous detachment?
- Floaters (vitreous opacities from degeneration, and sometimes haemorrhages from torn retinal vessels).
- Flashing lights (caused by traction on the retina).
Posterior vitreous detachment is very common. Usually the floaters and the flashing lights are a nuisance only, and reduce with time.
What is the management for posterior vitreous detachment?
No specific Rx is available, but the pt with an acute onset of vitreous detachment (less than 6 weeks) should be referred for dilated retinal examination, particularly if there is myopia.
What are the 5 clinical features of rhegmatogenous retinal detachment?
- Floaters/flashing lights
- Peripheral field loss (early retina, detachment)
- Loss of central vision (when detachment reaches macula. If fovea detaches, central vision deteriorates badly to ‘hand movements’).
- Loss of red reflex (degree of loss depends on the area of retina detached)
- Detached retina (grey, seems to balloon forwards)
Usually there is an antecedent Hx of vitreous detachment, but the importance of the symptoms go unrecognised and so presentation with visual loss is usual.
What are the four principles of surgical management of (rhegmatogenous) retinal detachment?
- Relief of vitreo-retinal traction (vitrectomy, or by indenting the eye wall from the outside with placement of a sutured explant).
- Closure of the retinal break (augment with injection of gas or oil).
- Drainage of the subretinal fluid (needle puncture through the sclera and choroid).
- Adhesion of detached retina to RPE (external cryotherapy or internal laser causes inflammation of choroid and retina -> adhesion).
What is the prognosis of (rhegmatogenous) retinal detachment?
Visual recovery depends on the duration of retinal detachment, and whether or not fovea, detachment occurred. If the detachment is a few days old only, the prognosis is good.
Surgery is usually successful, but reoperation is sometimes necessary (particularly if scar-like membranes grow across the retina, pulling it off (proliferative vitreoretinopathy).
Retinal detachment resulting from a macular hole, as may occur in high myopia and age-related macular degeneration, carries a poor prognosis but is fortunately rare.
What are two associations which may lead to tractional retinal detachment?
- Proliferative diabetic retinopathy
- In association with rhegmatogenous retinal detachment, contractile membranes may grow across the retina.
Tractional retinal detachment is difficult to treat. Optimal management of diabetic retinopathy should prevent this severe complication.
What are three chief causes of serous (exudative) retinal detachment?
- Posterior uveitis
- Intraocular tumours
- Central serous retinopathy, affecting the macula (proliferative diabetic retinopathy).
Retinal detachment without a retinal break is much less common.
What is serous (exudative) retinal detachment?
The breakdown of the blood-retinal barrier may lead to intraretinal oedema and subretinal (space) fluid.
The blood-retinal barrier comprises the junctions between adjacent RPE cells (outer barrier) and the tight junctions of the endothelial cells of the retinal vasculature (inner barrier).
What are the clinical features of exudative retinal detachment?
Will depend on the part of the retina involved. Usually only macular involvement will be symptomatic. The retinal detachment is much less extensive (both in area and in volume) and may not be detectable on direct ophthalmoscopy.
Mx depends on cause. Spontaneous reattachment may occur. Foveal detachment usually results in a permanent degree of impairment of visual activity.
