I have just examined a 65-year-old male patient. He was complaining of blurred, distorted vision in his right eye and problems with reading small print. He is healthy, denies taking any medication. Using a direct ophthalmoscope, I can see no signs of drusen or obvious age-related macular degeneration but the macular looks drawn over to one side as if there is some clear plastic lying on it. The other eye is normal. The right visual acuity is 6/9 and N8 at 35 cm. What is going on?
This sounds like an epiretinal membrane (ERM). These are thin, transparent layers of fibrous (scar) tissues that form a film on the surface of the retina. It is also known as macular pucker and cellophane retinopathy.
About 2% of people over 50 have one and this rises to 25% in people over 75.
These are the risk factors that predispose people to develop an ERM in one or both eyes:
Posterior vitreous detachment.
Retinal tear or detachment
Retinal vascular diseases
Existing ERM in one eye.
Although some people without any of these risk factors develop an ERM in one or both eyes and it is most likely due to aging.
ERMs usually cause a few mild symptoms. They are generally monitored and not treated. But in those instances where they cause loss of vision and visual distortion they may be treated. An ERM may contract and disrupt the structure of the retinal layers in the macula resulting in distorted and/or blurred vision. It sounds like from your description of the macula ‘looks drawn over to one side’ that this ERM has contracted. This also explains your patient’s symptoms of blurred and distorted vision.
They can be difficult to see using an ophthalmoscope or on a retinal photograph and the best way to identify an ERM is from an OCT scan. Not all practices have an OCT device.
The only treatment for an ERM is a vitrectomy.
As your patient is having symptoms (although his visual acuity at distance and near are good) he may want to be referred to discuss the advantages and disadvantages of a vitrectomy. All ocular surgery has risks and with vitrectomy these are risks of infection (endophthalmitis), bleeding retinal tear or detachment, and Progression of cataract. These risks are very low but you might want to discuss them with your patient before making any referral. Of course, brief notes of discussions, advice, and management should be noted in the clinical records.