A macular hole is a small gap that opens in the central macula, the portion of the retina responsible for central and fine vision. The retina that transmits messages along the optic nerve is a light-sensitive layer. Light rays enter the eye through cornea and then pass through the iris, the lens and the vitreous (a jelly like substance) before reaching the retina.
With age, the vitreous gel begins to shrink and during the process it pulls away from the retina. While in most cases, there is no negative effect of this vitreous separation, in some cases the movement of vitreous may result in formation of a hole in the macula. This is called macular hole. People suffering from the condition experience dark spot in central vision, distortion of the central vision or central visual loss.
Macular Hole Causes
Formation of macular holes happens when the vitreous, lying in front of the macula, pulls away because of aging. In some cases, the gel is unable to pull away because of which the macular tissue stretches. After several months, this causes a hole to open up in the macula.
Macular Holes Symptoms
Macular holes begin to appear gradually. As the disease progresses, the patient may experience the following symptoms:
- Decreased or blurred central vision
- Distortion in central vision
- Lines may begin to look wavy
Performing routine tasks such as reading becomes difficult.
Macular Hole Diagnosis
The condition requires a thorough eye examination. Your ophthalmologist will dilate the pupils and examine the retina. Optical coherence tomography (OCT) is routinely used to diagnose and stage a macular hole accurately. A special laser camera is used to take photograph of the retina and the test measures the thickness of the retina, swelling and fluid and records any defects or hole in the macular area. OCT can detect the smallest of macular holes that are sometimes too small to be seen by clinical examination alone. Sometimes fluorescein angiography may be used with OCT scans to clarify the diagnosis or clarify any diagnostic uncertainty, a yellow brown dye is injected into a vein in your forearm which goes with your natural circulation and makes its way to the retinal circulation. A series of pictures is then taken to study the retinal circulation.
Treatment of Macular Holes
Surgical procedure for visual improvement is the way to treat macular holes. The macular hole surgery procedure is called vitrectomy (also termed Pars-Plana Vitrectomy or PPV) and it involves microscopic removal of the vitreous gel from the centre of the eye. Particular attention is directed to removing any vitreous attachment from the macula, thereby releasing the traction on the retina. A fine layer, which is the innermost lining of the retina, called the Internal Limiting Membrane (ILM) is most often peeled away to ensure complete removal of traction which is keeping the macular hole open. This settles the retina against the wall of the eye.
A large gas bubble is placed within the eye which when comes in contact with the retina presses it against the wall of the eye sealing the hole. For the process to be effective, it is essential that the bubble must apply upward pressure against the retinal surface. As the macula is at the back of the eye, patients are usually asked to remain in face-down position to allow the bubble to rise towards the back of the eye. For successful closure, patients must maintain the face-down position for about 7 to 10 days and it is most vital do this if instructed to maintain this position by your retinal surgeon or nurse for closure of the macular hole.
It may take the gas bubble around 6 to 8 weeks to completely disappear. The surgery may be performed under general anaesthesia or local anaesthesia and may require an overnight stay. Following surgery, several eye drops will be applied for several weeks. Full recovery of vision can be as late as three months after surgery.
With any major surgery, there is a risk of complication and macular hole eye surgery is no different. It is essential to realise that it's generally infrequent. Any of the following complications can result in the failure of the operation, loss of some vision and in extremely rare situations, complete loss of the eye.
Very few patients develop retinal tears or detachments. These can be fixed in the postoperative period. Patients who haven't had cataract surgery, cataracts may develop within six months to two years. General risks include bleeding or infection.