A door frame that looks bent. A line of print with a gap in the middle. A face that has a blank patch where the eyes should be. These are the sort of changes that can come with a macular hole, a small break in the centre of the retina. It usually happens in one eye. This guide explains what a macular hole is, how it is found and how surgery can close it, drawing on the information published by the Macular Society, a UK charity for people with macular disease.
What the macula does
The retina is the light-sensitive layer of tissue that lines the back of the eye. The macula is a small area at its centre. It is responsible for all of a person’s central vision, most of the colour vision and the fine detail that can be seen.
When the macula is damaged, everyday tasks become difficult. It becomes hard to drive, watch television, read or recognise faces. This is why even a very small fault in this small area can have a large effect.
What a macular hole is
A macular hole is a small defect in the retinal layer that develops at the centre of the macula. The Macular Society says macular holes occur in about 3 in 1,000 people over the age of 55, and that they are more common in women than in men.
The cause is linked to the jelly, or vitreous, that fills the cavity of the eyeball. The jelly normally fills the eye fully and touches the surface of the retina. With age it becomes weaker and shrinks, and it pulls away from the retina. This is called posterior vitreous detachment, and it happens in most people as they get older.
In some people the jelly is unusually stuck to the retina. As it pulls away, it tugs on the retina and takes a small piece with it. That leaves a round defect. Unfortunately it is usually at the very centre of the macula, which handles the detailed visual work.
The early signs
In the early stage there may only be a slight distortion or blur. Straight lines may look wavy, and reading becomes difficult. Later symptoms include gaps, or the loss of the most central vision.
There is one warning to keep in mind. The sudden appearance of flashing lights, floaters or fading vision could indicate a retinal detachment. The charity says that in this case you should seek urgent medical help. Floaters are the specks or flecks that drift across the vision.
How vision is affected
A macular hole affects central vision. Side vision is unaffected, and the condition does not lead to complete blindness. If it is left untreated, vision will usually get worse, until a person may only be able to read the top letter of an eye chart, or even less.
Time matters. The charity says that the longer a hole is left, the less likely treatment is to succeed. That is why it is important to find macular holes early. Anyone who notices a sudden change in vision should be seen urgently.
The condition usually occurs in one eye only. There is a small risk, about 10%, that it will happen in both eyes. An optical coherence tomography scan, or OCT, helps the eye doctor to advise on the risk. A hole is more likely to develop if the vitreous gel is pulling on the retina. If the gel has already separated from the retina, a hole is unlikely to develop. A guide to what a dilated eye exam checks shows how the retina is looked at.
The operation, called a vitrectomy
Surgery for a macular hole is called a vitrectomy. The surgeon removes the jelly from the eye under local anaesthetic. A gas bubble is then placed in the eye. The bubble blocks the hole and lets the retina lie flat again, and the hole closes.
Recovery and the gas bubble
After surgery the eye may be sensitive, swollen and red. Eye drops are prescribed to prevent infection and to reduce inflammation. A guide to putting in eye drops safely covers the technique.
While there is gas in the eye, a person cannot see well. Over time the bubble gets smaller and rounder, until it looks like a golf ball bobbing around at the bottom of the vision. It sometimes splits into several bubbles, and the charity says that is nothing to worry about. The gas is absorbed slowly by the eye, so there is no need for another operation to remove it. Once the bubble has cleared, vision returns quickly, although improvement can continue for up to 12 months.
One rule needs to be remembered. A person cannot fly with gas in the eye. The gas would expand and raise the pressure inside the eye, which would cause pain and loss of vision. Any plan to travel by air should be discussed with the surgeon before the operation.
Posturing after surgery
Posturing means keeping the head face down for up to two weeks after surgery, so the gas or oil presses in the right place to help the hole close. If posturing is advised, equipment is available to make it more comfortable. The charity offers a few practical tips.
- Stock up on things to do while lying face down.
- Wear clothes without buttons, which are more comfortable to lie in.
- Keep the things you will need during the day close by, such as tissues, snacks, water and drinking straws.
- Plan meals so that they can be prepared quickly and easily.
A visit to the eye clinic is expected one to two weeks after surgery, and progress is commonly reviewed again after three months. A vitrectomy can change the glasses prescription. If a new prescription is given, do not get new glasses until the gas bubble has been absorbed, and ask the eye doctor for advice.
Possible complications
All eye surgery carries some risk, and the charity describes the main ones for this operation.
- Cataract. Cataracts develop in nearly all cases within 12 months of surgery. Because of this, cataract surgery and a vitrectomy may be offered together. A guide on cataract surgery in Karachi explains the cataract operation.
- Retinal tear or detachment. The retina may detach from the back of the eye during surgery. Retinal tears that can lead to detachment occur in up to 6% of cases. A person who has this will notice a shadow across the vision, and it needs urgent repair. The surgeon repairs any weak areas of the retina to try to prevent it.
- Raised eye pressure. This may cause glaucoma. Most cases settle without treatment, and when treatment is needed it is eye drops.
- Infection. It may occur in about 1 in 1,000 patients a few days after surgery. It needs urgent treatment with antibiotic injections and possibly more surgery.
- Bleeding in the eye.
Post-operative care is designed to detect these problems and to advise on them.
How likely surgery is to work
Vision improves gradually over several months. The charity says that an average improvement is being able to read two or three more lines on the eye chart. Success depends on how old the hole is. The treatment of holes younger than 6 months has a success rate of over 90%. For holes older than 12 months the success rate is lower. If a hole does not close after the first operation, more operations may be done, but the chances of recovering vision in that situation are often not very high.
Watching the other eye
A person with a macular hole in one eye may be at a higher risk of developing one in the other eye. It is important to watch for the symptoms described above. Any change in the vision of the eye at risk should be reported to an optometrist, who will assess it and may refer the person to an eye doctor.
Questions to ask the surgeon
- How long has the hole been there, and how does that affect the chance of success?
- Will a gas bubble be used, and will I need to keep my head face down?
- How long will I need to avoid air travel?
- Should the cataract be dealt with at the same time?
- When will I be seen after the operation, and which warning signs should I watch for?
If your central vision has changed
If straight lines look bent or the middle of your vision has gone blurred, have your eyes examined soon. For questions about a possible macular hole, ask PEBS about central-vision changes. Gifts are made through the donate page.
The longer a macular hole is left, the less likely surgery is to close it, so the day it is noticed is the day to book the examination.
Have a question about your eyes?
PEBS Hospital in North Karachi can examine you and explain your options. Call the helpline on 021-36908053, or send a message and the team will reply.
This article is general information and does not replace an examination by an eye doctor.
