Retinal detachment is a sight-threatening disorder. It comprises the separation of the retina from the underlying retinal pigment epithelium (RPE).
The RPE is a layer of nutritive cells, which are rich in melanin. They supply the retinal layers with nourishment and also restore the bleached photopigments to renewed activity. They also remove the photoreceptor disks which contain the visual pigments, in the outer part of the photoreceptor cells. They thus ensure that fresh pigment is always available in the eye. The dark melanin pigment also prevents the backscattering of light rays that have passed through all the retinal layers without being absorbed, by trapping them.
Symptomatic retinal tears and retinal detachment
Retinal detachment is of various types, of which the most common type is the rhegmatogenous detachment. This follows the development of retinal breaks or tears. Other types include tractional (due to the pull of scar tissue on the retinal surface) and exudative (as occurs in inflammatory conditions of the eye).
Symptomatic breaks are responsible for the highest incidence of rhegmatogenous retinal detachment. The presence of symptoms such as photopsia indicates the potential for detachment is high. Photopsia refers to the occurrence of flashes of light, often arc-shaped, in the peripheral field. It is the result of the retina getting detached towards the area of the optic disk.
The traction on the edges of the optic disk pulls on the axons passing through that area, stimulating the nerves and producing light flashes. At the same time, the traction forces liquefied vitreous beneath the borders of the break. This results in the accumulation of subretinal fluid and progressive detachment. Approximately half of such breaks are associated with retinal detachment, as compared to only 5% in asymptomatic tears of the retina. Hence this symptom is the most significant indication of the need for preventive surgery.
Again, in the case of atrophic holes, as are commonly seen in conditions such as lattice degeneration of the retina, only 2% progress to retinal detachment.
How to prevent retinal detachment
Most cases of retinal detachment are related to aging and related vitreous detachment. These are hard to predict or prevent.
However, prevention of retinal detachment starts with having regular routine eye examinations every year or two. These help your eye specialist to detect any changes such as inflammation, thinning or tears in the retina which could progress to retinal detachment.
High-risk factors for retinal detachment
People who should never put off regular eye examinations include:
- People with short-sightedness (high myopes)
- Those who have had retinal detachment in the past
- Those with a family history of retinal detachment
- Those with a history of cataract surgery, eye injury or degenerative eye disease
This is important also in people who have diabetes mellitus. Diabetes makes the retina more prone to a type of vascular disease (diabetic retinopathy) which may produce plenty of fibrinous or inflammatory exudate. This may lead to scarring and traction on the retina, encouraging retinal detachment. Diabetic patients should have a yearly eye examination with dilatation of the pupils to identify any retinopathy. In addition, they need to monitor their blood sugar levels as closely as possible.
Prevention of traumatic retinal detachment
Again, it is important to prevent eye injuries as far as you can. This involves wearing protective goggles when you are working with power tools or performing activities which involve small objects flying around (possibly into one eye). This also applies when you are using guns of any description, or participating in any type of fireworks show.
Similarly, when you take part in physical contact sports such as boxing, squash, or soccer, it is important to protect your eyes from a direct blow, which could lead to detachment of the retina, by wearing appropriate eye protection.
Preventive retinal tear repair
If a tear is present, your healthcare provider will examine you carefully to decide on whether to treat it or not. This depends on the type of tear, the etiology, other medical conditions, the previous medical history of the patient, and whether there is a history of any previous retinal break as well as its outcome.
Repair of any tear that is present in order to prevent retinal detachment may be done by laser photocoagulation or cryopexy. Laser energy is supplied to heat up the retina by the absorption of the light, to about 60 0C, inducing coagulation necrosis. In cryotherapy, a cryoprobe is applied to the eyeball to freeze the retinal tissue. Both techniques are aimed at scar formation, leading to reattachment of the retina onto the RPE at the region of the tear, provided both layers are in contact. Once macular detachment occurs, it may be impossible to regain central vision.