Retina Detachment: The major threat to vision
The retina is the neural tissue where an image is formed after it passes through the optic system of the eye. We can compare it to the film of camera. This is where the necessary chemical processes happen in order for the neural stimulations to be transported to the brain, via optic channels for analysis and processing. It is a thin semitransparent membrane which covers the inner surface of the eye. It is attached to the choroid and to the sclera.
During retinal detachment, the retina separates from the back wall of the eye. Upon detachment the retina is removed from its blood and nutritional supply. If it remains detached it will degenerate and will loose its ability to function. As a result the central vision will be lost.
The most common form of retinal detachment is the Rhegmatogenous type, which is due to a tear or break in the retina and the vitreous fluid fills the centre of the eye passing through the break and detaching the retina. The disease can happen to anybody, however there is a higher risk in people who are short sighted, have had a cataract operation or recently have had a severe blow to the eye.
- Photopsia: Flashes of light in the visual field.
- “Flies” Spots in the vitreous which can also present in the form of spiders webs or in rings.
- Disturbance of the visual field: in the form of a black curtain which may start from lower or upper hemisphere of the optic field and may include the central vision.
The first two symptoms appear mainly in the Rhegmatogenous type of detachment. The diagnosis is made with the use of a slit lamp – the ophthalmic surgeon’s microscope, where the anterior chamber is examined. The posterior chamber of the eye including the retina is examined after dilation of the pupil with medication placed in the eyes by form of drops. The examination is made also using special lenses which give a very good aspect of the retinal condition.
Treatment of retinal detachment:
A. Scleral buckle: All sites where the retina tears are located and treated by supporting them with a firm support of silicone.
B. Vitrectomy: Small incisions are made into the wall on the outer part of the eye to allow the introduction of instruments into the vitreous cavity, the middle of the eyeball, in order for the vitreous to be removed followed by the re-attachment of the retina.
C. Pneumatic Retinopexy: A gas bubble is placed inside the vitreous cavity before or after the retinal tear has been treated with Laser or Cryotherapy. This procedure is used to help the permanent closure of the tear, preventing the fluid from entering the eye during the healing period of the retina.
The percentage of visual sharpness after the above mentioned surgical procedures depends mainly on the status of the retina before the detachment. If the macula has not detached, then the expected vision will reach the same level as before once a successful operation for retinal detachment has been performed. However, if the macula did detach and the central vision has been affected then perhaps there will be a permanent loss of vision, even if the retina has been re-attached successfully .The longer the retina is detached the greater the danger of permanent loss of vision due to irreversible damage to the photoreceptor cells.
Dr Georgiou points out that a vitrectomy surgical procedure is a major advancement in medical therapies of the retina and prevents the loss of vision in patients who otherwise would have been driven to blindness without the availability of this technique.
The complications could be those of infection, haemorrhage, cataract, glaucoma and detachment or re-detachment of the retina. Any one of these complications could result in serious loss of vision even loss of the eye itself.