Epiretinal Membrane – Why Straight Lines Look Wavy

What is an epiretinal membrane?

Let’s break down the name:

• Epi = on top of
• Retinal = the retina (light-sensitive tissue at the back of the eye)
• Membrane = a thin layer or film

So an epiretinal membrane is:

A thin layer of scar tissue or “cling film” that forms on the surface of the retina, usually over the macula (the central area responsible for detailed vision).

You can think of it like a very thin, translucent plastic film that contracts gently and crinkles the surface of the retina.

What symptoms can an epiretinal membrane cause?

Epiretinal membranes are fairly common, particularly as we get older. Many are found incidentally during routine eye checks with an eye doctor and cause no symptoms at all.

When they do cause symptoms, the most typical ones are:

• Metamorphopsia
• Straight lines appear wavy or bent
• Objects may look slightly stretched, squashed or distorted
• Parts of a grid or page may look “pulled” or uneven
• Blurred vision
• Central vision may be slightly blurred or smudged

• • Fine detail is harder to see, especially for reading or fine work

Sometimes one eye is worse than the other; the “better” eye can mask the symptoms until the affected eye is checked on its own.

How do we diagnose an epiretinal membrane?

1. Clinical examination

At the slit lamp (microscope), an eye specialist can often see:

• A subtle glistening layer over the macula
• In more advanced cases, wrinkling or puckering of the macula and surrounding retina

2. OCT scan (Optical Coherence Tomography)

The gold standard for diagnosing and assessing epiretinal membranes is an OCT scan:

• • It’s a quick, comfortable, in-room scan
  • Produces a cross-section image of the macula in high resolution
  • In a normal OCT, the macula has a smooth, regular contour
  • With an epiretinal membrane, we often see:
    • A bright line or film on the surface of the retina

• The macula being pulled into folds or ridges

• • Distortion of the normal foveal dip

The more the retina is pulled and distorted, the more likely you’ll notice symptoms.

3. Amsler grid (distortion monitoring)

We may also use an Amsler grid, a simple grid of straight lines:

• With a healthy macula, the lines look straight and even

• • With an epiretinal membrane, patients may see:

• Wavy, bent or crooked lines

• Areas where lines disappear or look “broken”

• • Patches of distortion

This is useful both for diagnosis and for monitoring changes over time.

When do we consider surgery?

Not every epiretinal membrane needs an operation.

We look at several factors:

• How good is your vision?

• How bothersome is the distortion in daily life?

• How severe is the puckering on OCT?

• Is the condition stable or getting worse?

In general:

• Mild membranes with minimal symptoms → observe and monitor

• • Moderate to severe membranes causing:
    • Significant distortion
    • Reduced central vision

• Difficulty reading, driving or working
  → Retinal surgery (vitrectomy and membrane peel) is usually recommended

As an eye surgeon at the Lowveld Eye Institute with a focus on retinal surgery, I have detailed discussions with patients about the risk-benefit balance based on their work, hobbies and visual needs.

How is an epiretinal membrane treated surgically?

The only effective way to treat a symptomatic epiretinal membrane is to peel it off the surface of the retina.

This is done with a pars plana vitrectomy and membrane peel:

• Vitrectomy

1. 1. 1. Small (micro-incision) ports are placed in the eye
      2. The vitreous gel is removed to allow access to the macula

• Chromovitrectomy (using dye)

1. 1. 1. A special blue dye is gently injected over the macula
      2. The dye stains the epiretinal membrane (and sometimes the internal limiting membrane)

• This makes the membrane much easier to see and grasp safely

• Membrane peel

1. 1. 1. Using very fine microsurgical forceps, we:
         1. Pick up a small edge of the stained membrane
         2. Peel it away from the retina in a controlled fashion
      2. Diagrammatically, it looks like peeling cling film off a surface

• Possible gas tamponade

1. 1. In some cases, a small gas bubble is placed in the eye at the end of surgery
   2. This supports the macula while the retina settles
   3. Vision is blurry while the gas is present and improves as it absorbs

Thanks to small-gauge vitrectomy systems and modern instrumentation, this surgery is now:

• More comfortable
• Often done as a day procedure
• Associated with high success rates, particularly for reducing distortion

What results can you expect and how long does recovery take?

It’s important to set realistic expectations:

• This is not like the routine cataract surgery patients often know, where vision frequently improves dramatically within days.
• With epiretinal membrane surgery:

• • The retina may have been wrinkled or pulled for months or years

• • Once the membrane is peeled, the retina needs time to relax and flatten

• • Visual improvement can be gradual over weeks to months, and may continue to evolve

Typical outcomes:

• Metamorphopsia (distortion)
  • Often improves markedly and is the symptom that responds best

• Visual acuity (reading letters on the chart)
  • Usually improves, although the final level varies from person to person
• Some distortion may persist in longstanding or very advanced cases

Your individual prognosis will depend on:

• How long the membrane has been present
• How severely the macula was distorted beforehand
• Any other eye conditions (e.g. diabetes, previous retinal surgery, macular degeneration)

These factors are discussed in detail at your consultation with an eye specialist in Mpumalanga who regularly performs retinal surgery.

Living with an epiretinal membrane, when to seek help

You should consider seeing an eye specialist/eye doctor when;

• You notice new distortion, straight lines not looking straight
• One eye seems more blurred or warped than the other
• Reading, computer work or driving is becoming more difficult
• You’ve been told you have an epiretinal membrane and it’s worrying you

At your appointment we will:

• Check vision and glasses prescription
• Examine the macula and retina
• Perform an OCT scan
• Possibly use an Amsler grid to map distortion
• Discuss whether monitoring or surgery is the better option at this stage

Final thoughts

Epiretinal membranes are common and often mild, but when they start to affect your day-to-day life, modern retinal surgery can offer significant improvement – especially in distortion and visual comfort.

If you live in Nelspruit, Mbombela or the wider Mpumalanga region and are worried about wavy lines, distortion or unexplained blurred vision, consider booking a consultation at Lowveld Eye Institute to have your macula properly assessed. Early evaluation gives you more options and a clearer understanding of what to expect going forward.