Fuchs’ Dystrophy, Why Vision Is Worst in the Morning and When a Transplant Helps

Some people wake up with misty vision that clears as the morning goes on. In time it may take longer to clear, and glare from lights, especially at night, may become harder to bear. When this happens in a person in their forties or fifties, one possible cause is Fuchs’ endothelial corneal dystrophy, usually shortened to Fuchs dystrophy or FECD. It is a slow condition of the cornea that many people live with for years. For some it ends in a cornea transplant. This guide explains how the condition develops, what it does to vision and how it is managed, using information from RNIB, the sight loss charity.

What Fuchs dystrophy is

The RNIB page on Fuchs dystrophy describes it as an eye condition that affects the cornea, the clear front window of the eye. The cornea is made of different layers. FECD affects the innermost layer, the endothelium. It may cause the cornea to become swollen, cloudy and sensitive to light, and vision may decline as a result.

RNIB gives a few facts about who is affected. FECD is three to four times more common in women than in men. It usually affects both eyes. It is typically seen in people in their 40s and 50s, although it can appear much earlier or later. It usually develops slowly and affects people to different degrees. Some never have any real problem with vision, while others notice blurring and glare quite early.

Why some people develop it

Usually FECD is sporadic, which means there is no family history. It can also be inherited. If either parent has FECD, there may be a 50 per cent chance of developing it, a pattern called autosomal dominant inheritance.

RNIB gives reassurance to relatives. Because no treatment is needed unless vision is affected, family members do not need to be screened and do not need special extra care for their eyes. Regular routine eye examinations are enough. The condition affects only the eyes, and no other part of the body.

What the endothelium does

The endothelium is a single layer of cells lining the back of the cornea. Its main job is to keep the right amount of fluid in the cornea. It pumps out the excess and keeps the cornea clear.

A small number of these cells are lost as part of normal ageing, and this does not usually change vision. In FECD the loss speeds up and more cells than usual are lost. Eventually the endothelium stops working properly, and fluid builds up in the cornea. The cornea becomes thicker and swollen, which is called oedema, and vision becomes cloudy and blurred. For many people the process is slow, and they never develop problems with their vision.

A guide on corneal blindness and cornea transplant explains the wider picture of why damaged corneas matter.

Why the morning is worst

One of the first symptoms people notice is blurred vision first thing in the morning. The cornea naturally swells slightly when the eyes are closed in sleep, and this can be worse with FECD. Vision often improves through the day. This happens because, with the eyes open, fluid can evaporate from the surface of the cornea. RNIB adds that the blurring can get worse when the humidity is high.

Other changes can follow. Extra fluid in the cornea can make light uncomfortable, and bright conditions harder to see in. There may be glare and halos around lights, which are often more noticeable at night, for example when driving. Some people develop small drop-like bumps at the back of the cornea, called guttata. They can only be seen with a special microscope, and they scatter light and can cause glare.

The fluid can also affect how well a person picks out objects against a background when there is little contrast, such as white rice on a white plate. Colours may look washed out. If one eye is more affected than the other, picking up objects can become difficult, because reduced vision in one eye can cause a loss of depth perception.

In the longer term

Eventually some people find that vision no longer improves through the day. They have lost a substantial number of endothelial cells, and fluid now stays in the cornea all the time, keeping its layers swollen.

The outer layer of the cornea has many nerve endings. When it swells, the eyes can feel gritty and painful. The swollen cornea may also develop blisters on its surface. If this happens, the condition is called bullous keratopathy. A blister that bursts can cause sharp pain. Blisters can increase light sensitivity and glare, make the eyes water and feel sore, as if there were something in the eye, and, if they do not heal, they can scar the cornea and reduce vision. They can also make the shape of the cornea uneven, which affects the way light is focused.

RNIB stresses that for most people FECD develops slowly, and it is possible to go a long time without any symptoms.

How the symptoms are treated

If FECD is not affecting sight, or causes only mild symptoms, no treatment is needed. The eyes may be examined regularly to see how the condition changes over time.

• Morning blur. If vision is mostly affected in the morning and clears through the day, the eye doctor may suggest sodium chloride drops or ointment, which might help to remove excess fluid in some cases. They may not help every patient.
• Light sensitivity. Tinted glasses can reduce the light entering the eyes. The level of tint is a matter of personal choice and a balance between being dark enough to help with glare and still letting in enough light. Photochromic lenses, which darken in bright sunlight, may help, and so may polarised lenses, which reduce glare reflected from flat surfaces such as water.
• Night glare. An optometrist can advise whether clear prescription lenses with an anti-reflection coating might help.
• Blisters. Medicines may be prescribed for the pain. Some people also wear soft therapeutic contact lenses day and night, which act like bandages by protecting the exposed nerve endings and helping burst blisters to heal.

When a corneal transplant is considered

If the changes in sight begin to cause difficulties in daily activities, the eye doctor may recommend a corneal transplant, and RNIB says that corneal transplants can successfully treat FECD. A transplant removes all or part of the damaged cornea and replaces it with healthy, clear tissue from a healthy donor. It is possible to replace all of the cornea, or only some of its layers. A corneal transplant is also called a keratoplasty or a corneal graft.

For FECD the common operations replace only the innermost layers. They are called endothelial keratoplasty. The commonest is DMEK, in which only the endothelium and its supporting membrane from a donor cornea are used. RNIB says that because the transplanted layer is so thin, recovery is faster than with other kinds of transplant, the visual results are better, and the risk of rejection is lower. The other main kind, DSEK, also called DSAEK, gives the patient a new endothelium, the membrane and some of the layer beneath.

In both, the damaged layer is removed through a small cut and the new tissue is put in place. Just a few stitches, if any, are needed, and they are usually removed two to four weeks after the operation. A temporary air bubble acts like a bandage and holds the new layers in place. If the bubble is left in, the patient may be asked to lie on their back as much as possible for the first few days, and the bubble is harmlessly absorbed.

These operations generally have short recovery times, usually a few weeks or months, and a low risk of rejection. It can take up to six months for the full improvement in vision to be seen. Less often, if the middle layer of the cornea is scarred, a full-thickness transplant may be needed, which requires stitches and generally has a recovery of about 18 months.

How well transplants work

Both kinds work very well for FECD, because the condition does not come back in the transplant. Most people notice an improvement in sight in the first six months after the operation. Those who have an endothelial transplant are likely to see an improvement sooner than those who have a full-thickness one, because it is a keyhole operation that heals quickly.

No transplant is free of risk. A graft can sometimes need to be repeated if there are problems with rejection. Rejection happens when the body’s defences recognise the transplanted tissue as foreign. It is usually possible to treat it with anti-inflammatory drops that reduce swelling, and the risk is reduced by using steroid eye drops. The new cells can also fail for other reasons, including injury, infection and natural loss of cells. If a graft fails, the cornea becomes swollen and cloudy again.

Tissue for these operations comes from donors. A guide to the cornea shortage and what a waiting list means explains why donated corneas matter.

Cataracts and Fuchs dystrophy

Fuchs dystrophy and cataracts both become more common with age, so they often occur together. RNIB says they do not interact and do not make each other worse.

There is one caution. Any eye surgery, including cataract surgery, can further reduce the number of healthy endothelial cells in a person with FECD. This may lead to swelling and clouding of the cornea, and it sometimes has to be followed by, or combined with, an endothelial transplant. For this reason it is important for a person with FECD to have the cornea examined carefully before cataract surgery. The surgeon may decide to do both operations together, or to let the eye settle after the cataract operation first. A guide on cataract surgery in Karachi describes the cataract operation itself.

Coping with the diagnosis

It is natural to be upset when diagnosed with an eye condition, and normal to worry about the future. Talking about those feelings with someone outside the family can help. RNIB also points out that many people with FECD do not have many problems with vision. When they do, much can be done to make the most of remaining sight, such as making things bigger, using brighter lighting or using colour to make things easier to see.

If you are worried about your vision

If you wake with blurred vision that clears slowly, or if glare at night has become a problem, have your eyes examined. For questions about morning blur or Fuchs’ dystrophy, ask PEBS about Fuchs dystrophy. Those who wish to give can review the hospital’s donation methods.

A blur that clears slowly through the morning is a clue worth taking to an eye doctor.

This article is general information and does not replace an examination by an eye doctor.