The retina is the delicate lining at the back of the eye where the image you see of the world is formed and transmitted to the brain.
Under certain conditions, especially with advancing age, the clear gel-like fluid which fills the eye can begin to recede. As it does, it sometimes pulls the retina along with it, tearing minute holes in the fragile membrane.
Left untreated, fluid seeps through these holes causing the layers of the retina to separate and detach. Depending on the degree of detachment, partial or total blindness may be the result.
Among those most at risk for retinal detachment are older adults and people with severe nearsightedness or a family history of the condition. A severe blow to the eye, tumours or complications from diabetes can also cause the retina to detach.
What to look for
The symptoms of retinal tears sometimes include sudden, unexplained flashes of light and moving black spots in the vision called "floaters." In most cases, these symptoms do not indicate serious eye problems; they can, however, indicate a substantial shrinking of the vitreous and attendant retinal tears.
If you experience floaters or flashes, please call to arrange an eye examination. New retinal tears may be easily treated with laser before they lead to a more severe retinal detachment.
Symptoms of detachment
When part of the retina detaches, the rods and cones are pushed and pulled out of their normal orientation and no longer work properly. The result can often be the rapid appearance of a dark shadow in the field of vision, and loss of vision.
Some detachments can occur very suddenly, causing the patient to experience total loss of vision in the affected eye.
Detection and Diagnosis
There are numerous tools and techniques your doctor may use to examine the retina.
The ophthalmoscope is used to examine both the central and peripheral retina. In both procedures, your pupils will first be dilated, allowing the retina to be examined under bright light and magnification.
The slit lamp combines a microscope with strong illumination. It is often used with a hand-held lens, allowing doctors to see portions of the retina in greater detail.
Treatment of Retinal Tears
Usually, retinal tears are at the edges of the eye and affect only your peripheral vision; doctors often monitor small breaks without treatment.
If treatment is determined to be appropriate, however, your doctor will probably recommend either cryotherapy or laser treatment.
In cryotherapy, a local anaesthetic is applied to the eye and the small area around the break is completely frozen with a probe. As the frozen area heals, it forms scar tissue which reattaches the retinal layers at the point of the break.
Lasers use an intense beam of energy to, in effect, weld layers of the retina back together, again by causing scar tissue to form.
Treatment for Detachment
Once the retina is detached, an operation is needed to fix the problem. Drops, tablets or laser alone are insufficient. The surgery required is extremely specialised and admission to hospital is required, sometimes urgently.
The operation aims to close the holes in the retina that have caused it to detach. Most commonly, a thin piece of silicone rubber is sutured onto the white of the eye (it is not visible from the outside) so that it makes an indentation directly under the retinal hole, to give it support. At the same time the hole is treated with freezing therapy (cryotherapy) to seal it off. This is called a "scleral buckle" operation. Alternatively sometimes an operation on the inside of the eye (vitrectomy) is needed to reattach the retina.
What to expect
The vast majority of all retinal detachments can be reconnected using modern surgical techniques. However, the degree of vision which returns within the next six months varies depending on a number of factors.
Excellent vision returns to about four in ten. The remainder will achieve differing amounts of detail and/or distance vision depending on the degree to which the macula - and area of the retina detail and responsible for straight-ahead, colour vision - has been involved.