Macular hole and epiretinal membrane: when to monitor, and when is surgery needed?

Some patients notice that straight lines have become wavy: a door frame, the edge of floor tiles, or lines of newspaper text. Others notice a blurred patch right in the middle of their vision, so they can see the outline of a face but not its features clearly. When a patient comes with these complaints, the question is usually: "Is this a cataract, or something more serious?" Often the cause lies in the macula itself: either a membrane that has formed on its surface, or a small hole in its center. Although the two conditions are sometimes treated with the same type of surgery, the decision and the timing are very different.

First: what is the macula?

The macula is a very small area in the center of the retina, but it is responsible for all fine vision: reading, recognizing faces, and seeing detail and color. Because it is small and sensitive, any pulling, wrinkling or opening in it shows up directly in central vision, while side vision usually stays intact.

Epiretinal membrane (macular pucker)

What is it?

A thin, transparent layer like cellophane that forms on the surface of the macula. Over time it may contract, causing wrinkles in the retina underneath, just as fabric wrinkles when you pull it from one point.

What are the symptoms?

Wavy straight lines, blurred central vision, and sometimes objects looking larger or smaller in the affected eye than they really are. But many mild cases cause no symptoms at all and are found by chance during an examination.

Is it common?

Fairly common. In an Australian population study, a membrane was found in about 7% of people over 49 years of age, and it was more common in those who had had cataract surgery. On average its effect on vision was small (Mitchell et al., 1997).

When do we monitor, and when do we operate?

This is the key question. Having a membrane does not by itself mean an operation is needed. Mild cases that do not affect the patient's life are followed with examinations and optical coherence tomography (OCT) of the retina. This scan shows the thickness of the membrane and how much it affects the layers of the macula, and helps us judge the stage (Govetto et al., 2017).

When the membrane affects vision or bothers the patient with reading, work or driving, it can be removed surgically through a vitrectomy, after which the membrane is "peeled" off the surface of the macula with very fine instruments. The decision here depends on how much the symptoms bother you more than on how the membrane looks on the scan. We discuss with each patient this balance between the expected benefit and the risks of surgery.

Together with the membrane, the surgeon may remove the internal limiting membrane, the thinnest layer on the surface of the retina. In an analysis of many studies, removing it reduced the chance of the membrane coming back, while long-term vision results were similar either way (Huang and Li, 2021).

Macular hole

What is it?

A small opening exactly in the center of the macula. It is usually caused by the vitreous gel pulling on the macula as it separates naturally with age. The vitreous is firmly attached at this point, and as it starts to move away it can "pull" part of the center with it.

What are the symptoms?

A blurred or missing patch in central vision, and distortion of lines. Patients often discover it by chance when they cover their good eye.

Is it common?

Macular hole is uncommon. In an American population study, about 8 people per 100,000 per year developed one, and it was about three times more common in women. The other eye became affected in about 12% of patients (McCannel et al., 2009).

How is it diagnosed?

Optical coherence tomography (OCT) is the key test. It confirms the diagnosis, shows whether the vitreous is still pulling on the macula, and measures the diameter of the hole (Duker et al., 2013). The size of the hole is one of the best predictors of the result: the smaller the hole, the better the chance of closure and of improved vision (Ullrich et al., 2002; Steel et al., 2021).

Can the hole close on its own?

This happens sometimes, but it is not the rule. In one clinical trial, about 1 in 10 holes closed in the group that received a sham injection. In the same trial, a medicine injected into the eye to release the attachment of the vitreous closed about 40% of holes (Stalmans et al., 2012). So most full-thickness holes need surgery.

Surgery: what happens?

Macular hole surgery was first described in the early 1990s (Kelly and Wendel, 1991) and has improved greatly since then. It usually involves four steps:

1. Removing the vitreous gel that is pulling on the macula.
2. Peeling the internal limiting membrane around the hole. In clinical trials this step increased the closure rate and reduced the need for a second operation (Lois et al., 2011; Spiteri Cornish et al., 2014).
3. For large holes, the surgeon may use the "inverted flap" technique: leaving part of this layer attached and folding it over the hole as a "roof" that helps it heal. This technique has been linked to higher closure rates in relatively small trials (Michalewska et al., 2010; Yu et al., 2021).
4. Placing a gas bubble in the eye, which presses on the edges of the hole from inside and helps it close.

No single approach suits every case. The choice of technique depends on the size of the hole, how long it has been present, and the state of the eye.

Expected results: closing the hole is one thing, better vision is another

This is the most important point in the whole article. In a large British database of about 1,500 operations, the hole closed in 96% of operations. But reaching a good level of vision happened in fewer than half, about 46% (Steel et al., 2021).

In other words, anatomical success (closing the hole) is achieved in the vast majority of patients, while functional improvement (how much vision returns) varies a great deal from one patient to another. Results were better with smaller holes, a shorter time with symptoms before surgery, and better vision before surgery (Steel et al., 2021). That is why the researchers recommended operating early to help reach better vision (Steel et al., 2021).

These figures come from external studies and are not a promise of any patient's result.

Face-down positioning after surgery: is it necessary?

This question worries patients a lot, and the honest scientific answer is that it is not fully settled. In a British trial on large holes, the closure rate was slightly higher with face-down positioning, but the difference was not statistically certain, while vision improvement was better in that group (Pasu et al., 2020). A review of several trials found that positioning may have little or no effect on hole closure, that the evidence is of low certainty, and that positioning is uncomfortable for many patients (Cundy et al., 2023).

So follow your surgeon's instructions: they will decide the position and its duration according to the size of the hole and the type of gas.

What can you expect after surgery?

• The gas bubble: vision is very poor at first because the gas fills part of the eye, then gradually improves as it is absorbed. While the gas is present, flying and traveling to high altitudes are not allowed, and any anesthesiologist must be told about it (Moorfields Eye Hospital NHS Foundation Trust, 2020). More detail is in our article on the gas bubble after retinal surgery.
• Cataract after surgery: if your eye still has its natural lens and you are over 50, a cataract is expected to develop faster after vitrectomy, especially when gas is used (Cherfan et al., 1991; Thompson, 2004). You may need cataract surgery later, and sometimes the surgeon performs both operations together (Pasu et al., 2020). See our article on cataract surgery after vitrectomy.
• Gradual improvement: vision keeps improving for several months, and some distortion of lines may remain.
• Go back to the doctor immediately if you develop increasing pain, a shadow in your vision, or a sudden severe drop in vision.

Questions patients often ask

Is an epiretinal membrane dangerous?

Usually not. On average its effect on vision is small (Mitchell et al., 1997), and the decision to operate depends on how much it bothers you.

Can a macular hole affect the other eye?

It can, but only in a small proportion of patients (McCannel et al., 2009). So we examine the other eye, and we advise patients to check their vision by covering each eye in turn from time to time.

Will my vision go back to what it was?

Vision improves in many patients after the hole closes, but the degree of improvement depends on the size of the hole, how long it was present, and vision before surgery (Steel et al., 2021).

Can the membrane come back after it is removed?

It can, but removing the internal limiting membrane reduces this chance (Huang and Li, 2021).

Summary

Epiretinal membrane and macular hole both affect the most delicate area of the retina, but the decisions are different. A membrane is often monitored, and we turn to surgery when it affects the patient's life. A full-thickness hole usually needs surgery, and the result is better when it is done at the right time. In both conditions, we make sure the patient understands the difference between anatomical success and the expected improvement in vision, so that the decision is based on realistic expectations.

This information is for health education and does not replace a medical examination.