The retina is the neurosensory tissue that lines the back wall of the eye. Like the film in a camera, the retina is responsible for creating the images that one sees. The center of the retina is called the macula and is the only part capable of fine detailed vision, i.e. reading vision, recognizing faces, etc. The remainder of the retina , the peripheral retina, is for side vision. The retina outside the center of the macula, which makes up more than 95% of the retina, is not capable of the fine detailed vision.
This is a condition affecting older people between the age of 60-80 years of age. It is somehow three times more common in women than men and although it usually affects one eye it can also affect the second eye in 5-10% of patients.
Most patients complain of blurry and patchy vision. More commonly there may also be distortion of images and lines when looking straight ahead.
The diagnosis of macular hole is made after a complete ocular examination which includes dilated retinal examination. If the condition is suspected or confirmed a simple non invasive investigation called an OCT (Optical Coherence Tomography) is performed to study the nature of the macular hole.
Early macular holes do not need treatment as there is a good chance it will resolve. However established holes will usually progressively get worse and cause loss of central and reading vision. The only treatment option is a surgery called vitrectomy and then using a medium to long acting gas to close the retinal hole. The success of the operation involves careful removal of membranes around the hole and maintaing face down posture for up to 2 weeks on a very strict basis to allow the gas to close the hole. The success rate of this operation is up to 90% with improvement of vision of more than 50 %.
This condition may be either idiopathic ie no known cause or secondary to other ocular abnormalities eg eye injuries, surgery etc.
If idiopathic, it most commonly occurs in older people above 50 years of age. Males and females are equally affected and may affect both eyes in up to 20% of people.
Some patients may have no symptoms if the membrane is thin and does not cause distortion of the retina. However worsening can occur if there is progressive thickening of the membrane. This can cause significant decrease and distortion of vision.
The diagnosis of macular hole is made after a complete ocular examination which includes dilated retinal examination. If the condition is suspected or confirmed a simple non invasive investigation called an OCT (Optical Coherence Tomography) is performed to study the nature of the membrane and the relationshio to the retina.
If there are no significant visual complains or if they are mild and which does not seem to be worsening the condition can be observed. Surgery is able to help if there is visual blurring. An operation called vitrectomy is performed to allow the membrane to be peeled from the retinal surface. Most patients will experience subjective improvement of vision.
The eyeball is filled with a clear transparent semi solid gel like substance called the vitreous humour. It normally completely fills the eyeball and it sticks to the entire surface of the retina. However it undergoes liquefaction(becomes watery) and falls away from the retina and floats freely in the cavity of the eye, This process is called posterior vitreous detachment(PVD). This occurs naturally in normal people as a result of ageing and commonly occurs in middle aged people. It is also more common in shortsighted people and also after cataract surgery.
Floaters are the symptoms of this condition although other conditions like bleeding in the eye eg from diabetic retinopathy or inflammation can also cause floaters. The can take various forms and appear as dots, spots or lines or cobwebs. In the initial stages it is often associated with flashes of light which are sensation of streaks of light with movement of the eye. This can appear even in the dark as it is due to retinal stimulation from movement of the gel. The pulling of the gel can cause retinal bleeding or in more severe cases tears of the retina.
Floaters and flashes are important symptoms that need to be attended to. This is especially if they are new and of recent onset. The only way to exclude retina bleeding or tears is to have a full eye examination including a dilated retina check. Fortunately most people do not have any retina problems following the vitreous detachment and the floaters will then gradually subside. The symptoms will persist for weeks to months and in some people will continue be annoying. There is no specific medical treatment for vitreous floaters and surgery is not usually advised. Tears of the retina may be treated with laser to seal the tears and prevent retinal detachment from occurring.
Tears of the retina can lead to a condition called retinal detachment where the retina separates from the back wall of the eye. This is a serious condition that requires urgent attention. People with moderate to high myopia, or had cataract surgery, accidental eye injuries or a family history of retinal detachment are at higher risk for this condition. Sometimes it occurs in middle age for no apparent reason following vitreous detachment and tears of the retina.
The symptoms are progressive loss of vision field that looks like a curtain or shadow blocking the vision. They may be preceded by floaters and flashes . Sometimes small detachments may have no symptoms.
Once the retina has detached it is usually not possible to treat with laser and surgery is required to reattach the retina. There are a few options for surgery and this depends on the nature and type of retinal detachment. It may take the form of injections a gas bubble into the eye, tying a silicone band around the eyeball (scleral buckle operation ) or a vitrectomy to remove the source of traction and filling the eye with gas or silicone oil.
The results of surgery for retinal detachment are generally good and the success rate ranges from 85% to 95%. However in some cases the retina cannot be attached in one operation and further surgery may be required. In general there will be recovery of vision but the final outcome varies from case to case.
Camden Medical Centre,
1 Orchard Boulevard,
Tel: 6738 2000
Fax: 6738 2111