What is a Macular Hole?
A macular hole is a small break in the central part of the retina which is called the macula. The retina is like the film in a camera and lines the back wall of your eye like wallpaper. The retina is essentially nerve tissue which converts the images we see into electrical signals which go to your brain which it interprets thus allowing us to see. The macula provides the sharp, central vision we need for reading, driving, recognising faces and seeing fine detail.
Macular holes occur more commonly in those over middle-age however it is not the same as age-related macular degeneration and your eye doctor will be able to confirm which condition you have, usually with a retinal scan to confirm.
What is the cause of a macular hole?
Our eyes are filled with a clear collagenous jelly-like tissue called the vitreous body. As we age, the vitreous slowly shrinks and pulls away from the retinal surface. Some of the collagen fibres coalesce and form floaters (See “Floaters” [hyperlink]), which are little black dots you may notice in your field of vision on a bright background or sunny day. Sometimes, and by luck, if the vitreous pulls on the central macula, it can create a hole. Why some people get this and others don’t is still unknown. Macular holes can also occur in other eye conditions, such as high myopia, eye injuries, retinal detachments and epiretinal membranes.
What are the symptoms of a macular hole?
In the early stage of a macular hole you may not notice any problems at all or may notice a slight distortion or blurriness in your central vision. Straight lines or objects can begin to look bent or wavy. Reading and performing other routine tasks with the affected eye becomes difficult. Some people may only notice it if they cover their unaffected eye as sometimes your brain compensates by ignoring the affected eye especially if the affected eye isn’t your dominant eye.
In people who have high myopia, a macular hole can also increase your risk of developing a macular-hole detachment or rhegmatogenous retinal detachment (See “Retinal Detachment”[hyperlink]). In these individuals, you can get rapid loss of vision in the affected eye and it is more urgent that this is attended to by a retinal surgeon.
Is my other eye at risk?
If you get a macular hole in one eye, there is a 5 to 10 percent chance that you may develop a macular hole in your other eye at some point in your lifetime. This is why it is important to get both eyes checked or scanned at regular intervals.
How is a macular hole treated?
Macular holes are graded into 4 main stages which depend on its extent and size as measured on a retinal scan. This helps your retinal surgeon advise you on the best course of action for your particular condition. Sometimes very early stage macular holes can resolves themselves and may only require close monitoring. Most macular holes however can progress through the stages quickly and though the symptoms may appear only gradually they usually become very noticeable in the later stages. It is unlikely that the more advanced stage macular holes seal themselves and they actually fare better with surgical intervention.
The surgery is called a vitrectomy and is essentially a micro-keyhole surgical technique used frequently by retinal surgeons to remove the vitreous (jelly) from inside your eye and to repair your retina. A medical-grade gas is then inserted to encourage the macular hole to close. The surgery can be done under local or general anaesthesia on a daycare basis. The gas inserted into your eye will blur your vision until it dissipates completely on its own after a few weeks. In this time that you have gas in your eye, you are advised to:
- Do not travel by air
- Do not go uphill (do not go up more than 1000 feet in elevation)
- Do not rub your eye
- Do not go swimming or diving
- Do inform your anaesthetist or dentist if you are having another procedure whilst you still have gas in your eye
It is important to take the above precautions as any change in environmental pressure can cause the gas bubble inside your eye to expand thus increasing the pressure within your eye. This can cause you a lot of pain and possibly blindness if not addressed promptly. Following surgery, some patients may be advised to remain in a face-down position which your doctor will describe further. Once the gas dissipates, the natural fluids in your eye fills the whole eyeball.
What are the risks of surgery?
Eye surgery nowadays is very safe however as with any operation there may be risks which are usually outweighed by the benefits of improved vision. The most common complication of this surgery includes developing a cataract. Since most people with a macular hole are in the age-group who may have a cataract anyway, it is usually advised to have this operated on simultaneously for 3 reasons. Firstly, removing a cataract before any retinal surgery improves the surgeon’s view of your retina. Secondly, this negates the (high) complication of worsening of the cataract and you only need 1 operation instead of 2. Lastly, if you require a cataract operation at a later date, there is a 7% chance that your macular hole could re-open, possibly requiring you to have another retinal operation to close it again.
Other less common complications include retinal detachments, recurrence of the hole, scar tissue growth on the retina etc. The risk of severe complications is rare with only about 1 in a thousand people (0.1%) losing vision in the operated eye due to severe infection or bleeding. The risk of the other eye being affected by a complication is less than 1 in 10,000.
How successful is this surgery?
The anatomical success rate of this surgery is usually 80% to 95% however visual improvement varies between individuals and depends of a few factors. This includes your age, how long you have had the macular hole for and the size of your macular hole. As with most conditions, the earlier it is detected and treated, the better the outcome. This is especially so with the retina as it is nerve tissue and cannot be replaced. Furthermore it can take between 3 to 6 months to gain full visual recovery however most patients will notice an improvement in their vision as soon as the gas bubble dissipates from your eye. Your eye doctor will be able to help explain your individual chance of visual improvement and ensure you know what to expect.