Corneal scarring: causes, urgent warning signs and treatment options

The cornea sits in front of the pupil and iris and lets light into the eye. The NHS describes it as the clear, outer part of the front of the eye. Because it needs to be transparent, any lasting mark, haze or clouding in it can interfere with how light reaches the retina and can blur or distort vision.

Corneal scarring is the term used when the cornea has healed after damage with an area that is no longer fully clear. How much it matters depends on where the scar is and how dense it is. A small scar at the edge may make no difference to sight, while one over the centre of the cornea can reduce vision considerably. The sources used for this page do not give more detailed grading, so your eye specialist is the best source on your own scar.

Scarring is the outcome of an earlier problem, rather than a disease in its own right, which is why the useful questions are what caused it and what can be done to protect the eye from further harm.

The NHS lists the following as causes of damage that may eventually require a transplant, and each can also leave scarring. Shingles affecting the eye and chemical injuries are further causes of eye damage covered in separate NHS pages.

Prompt treatment of corneal injury and infection is the main way to reduce the risk of scarring. The NHS gives clear advice on when an eye problem cannot wait.

• Go to A&E or call 999 if a strong chemical such as oven cleaner or bleach is in your eye (keep rinsing with water for at least 20 minutes while waiting), a sharp object has pierced your eye, something has hit your eye at high speed, or there are any changes to your sight after an injury.

• Go to A&E or call 999 for severe pain in the eye, a headache or sensitivity to light, feeling or being sick after an eye injury, being unable to move your eye or keep it open, or blood or pus coming from the eye.

• Ask for an urgent GP or optician appointment, or call NHS 111, if you have a red eye and wear contact lenses, or your eye is very painful and red (NHS red eye advice).

• Call 999 or go to A&E for a red eye with changes to sight, such as wavy lines, flashing or loss of vision, or pain on looking at light.

• Ask for an urgent GP appointment or call NHS 111 if you have shingles symptoms and the rash is on your eye or nose, or you have changes to your vision.

• Do not touch or rub your eye, and do not wear contact lenses until the eye is better after an injury.

Corneal scars do not always cause symptoms. Where a scar does affect vision, the effect is typically blurring or cloudiness, and sometimes a visible pale patch on the eye. The NHS advice above treats sudden changes in sight as an emergency; slower changes should be checked by an optician, who can refer you to an eye specialist.

Because a cornea can become cloudy for several reasons, such as an inherited dystrophy or keratoconus, a new cloudy patch should not be assumed to be an old scar. An eye examination is needed to tell them apart.

An optician or eye specialist examines the front of the eye, usually with a microscope that lets them see the cornea in detail, and asks about past injuries, infections, contact lens use, previous eye surgery and family history. If an optician cannot find the cause of a problem, the NHS says they may refer you to an eye specialist (ophthalmologist) for tests.

The sources used for this page do not describe individual corneal tests. In practice the specialist is judging where the scar is, how deep it goes, whether the rest of the cornea is healthy, and how much it affects vision.

The sources used for this page do not describe a drop or home treatment that removes an established scar. Options depend on how much the scar affects vision. Minor scars away from the centre are often left alone and monitored. Glasses or contact lenses may be enough when the scar causes irregular focusing. The NHS says a cornea transplant is usually done if glasses or contact lenses are no longer enough to improve vision, or you have eye pain.

The NHS describes a cornea transplant as an operation to replace all or part of a damaged cornea, taking 1 to 2 hours. Most people go home the same day, though some stay 1 to 2 days. The operation removes and replaces either all layers of the cornea or only the damaged layers, using a cornea from someone who has died and donated it, which is checked to make sure it is healthy. You may have a local anaesthetic with a sedative, or a general anaesthetic.

Recovery can mean around 2 weeks off work, with some swelling, redness and discomfort. Vision takes time to improve, and the NHS says this can take up to 6 months if only the inner layer was replaced, up to 18 months if the outer and middle layers were replaced, and up to 2 years for a whole cornea transplant. You will usually still need glasses or contact lenses.

The NHS lists complications including transplant rejection (which can usually be treated with steroids if found quickly), clouding or displacement of the new cornea, astigmatism, inflammation or pressure in the eye, infection, detached retina and cataracts. It advises calling your care team straight away if you have a red eye, eye pain, sensitivity to light, blurred vision, new floaters or flashes, or a dark curtain across your vision.

If a scar affects vision, practical steps include good lighting, anti-glare lenses, and discussing driving with your optician. The NHS says not to drive after a transplant until your vision has improved enough to drive legally and your doctor says it is safe, and points to GOV.UK for eye conditions and driving. Looking after the eye matters too: avoiding rubbing it, using protective eyewear for risky jobs and DIY, and getting prompt help for any new redness or pain.

Long-term follow-up matters if you have had a transplant. The NHS says follow-up appointments are in the first week, then usually every few months for the next 1 or 2 years, or sometimes longer, and that eye drops are needed long term to reduce the risk of the transplant failing.

Eye emergencies are treated at NHS A&E or eye casualty departments, and corneal specialists and transplants are provided through NHS hospital eye services using donated tissue. Some people see a private ophthalmologist for assessment or a second opinion. If you do, share your NHS records and scan reports so that treatment is coordinated, particularly if a transplant is being considered.