Keratoconus – symptoms, causes and treatment

Medically reviewed by Sharon Copeland on 16 December 2021

Keratoconus is a bilateral eye condition that affects the structure of the cornea (the transparent front part of the eye). In this condition, the cornea which is generally round becomes uneven and cone shaped and bulges out, resulting in blurry vision or distorted vision. This disorder tends to develop most often during puberty.

This problem usually occurs in both eyes. Generally, one eye will get affected before the other. However, it can be genetically passed too. If you have a family history of this condition, it is best to look out for the signs of this disease and consult an optician.

What causes keratoconus?

According to the NHS, the exact cause of this condition is unknown. However, this problem is more common in people with the following conditions:

• Repeatedly rubbing your eyes
• Conditions such as asthma, hay fever, retinitis pigmentosa, down syndrome and Ehlers Danlos syndrome
• Having a family history of this eye condition

Symptoms of keratoconus?

Many people experiencing eye discomforts are unaware that they have this eye condition.

Symptoms include:

• Red eyes
• Swollen eyes
• Distorted vision
• Mild blurred vision
• Light sensitivity (photophobia) to bright light
• Increased sensitivity to bright light and glare
• Need for frequent change in spectacle prescriptions
• Sudden worsening or clouding of vision

How early can keratoconus be diagnosed?

This eye condition is usually detected during a person’s early 20s or teenage years. For diagnosis, your optician will review your medical and family history and conduct an eye exam. Various tests can be carried out to examine the details regarding the shape of your cornea. It can be detected through the following means:

• Slit lamp examination - a vertical beam of light is directed towards the surface of your eye. A low powered microscope is used to view the shape of your cornea and spot the other potential problems.
• Eye refraction – looking through a device containing different lenses to see which combination gives you the best/sharpest vision.
• Keratometry – this test examines the cornea’s basic shape by focussing on circle of light on your cornea.
• Computerised corneal mapping – includes photographic tests (such as corneal tomography and corneal topography) that records the images to see how uneven and curved your cornea has become.

How is keratoconus treated?

Mild cases of keratoconus can be treated with contact lenses or glasses. Remember, although contact lenses do not slow down the rate of progression of the cone, but they aid in a better vision. First line of treatment is usually to correct irregular cornea with rigid gas permeable (RGP) contact lenses. Further, it can also be corrected by using sclera or combination of soft lenses. The treatment will depend on the severity of your problem and how rapidly it is progressing.

Contact lenses for keratoconus

• Custom soft contacts – these custom lenses are designed according to the detailed measurements of the person’s keratoconic eye(s).
• Hard contact lenses - for advanced keratoconus, hard (rigid, gas permeable) contact lenses are often the next step. These lenses can be customised to fit your cornea. Although wearing hard lenses can be painful at first, but eventually many people adapt to them and find that they provide excellent vision.
• Piggybacking contact lenses - this involves placing a soft contact lens, such as silicone hydrogel contact lenses in your eyes first and then covering it with a hard lens. This piggybacking approach increases the wearer’s comfort (as the soft lens acts as cushioning).
• Hybrid contact lenses - people who can't tolerate hard contact lenses may prefer hybrid lenses.
• Scleral lenses – these lenses are used for advanced keratoconus. Unlike other lenses, these lenses sit on the white part of the eye (sclera) and leap over the cornea without touching it.

Corneal cross linking

If your keratoconus is rapidly progressing, corneal cross linking (CXL) is a new method to treat this condition. This helps in slowing down or stopping the progression. Rather than replacing any tissue, cross-linking strengthens the cornea and works to prevent any further deterioration. It is an invasive treatment which includes the use of eyedrop medication and ultraviolet (UV) light from a machine to stabilise cornea’s shape.

This treatment doesn’t reverse keratoconus but helps to reduce its progression by stabilizing the cornea in an early stage. After the treatment, you might need new glasses or contacts.

Corneal transplant

Transplant is an extreme case. Some patients with keratoconus can't wear rigid contact lenses. This is because they have reached a point where contact lenses or therapies can no longer aid in effective vision. For such patients, the last remedy to be considered is a cornea transplant.

Keratoconus – parents supporting children

Since this condition tends to develop most often among adolescents or at around puberty, it is essential for parents to support their kids by understanding their experience and communicating with them. Here are some points to help parents support their kids with this eye condition:

• Parents should encourage their children to avoid rubbing their eyes repetitively and vigorously by telling them how this habit can harm their eyes more; if they continue to do so, a consultation should be booked with an optician.
• If you have a family history of this condition (if you are a parent having this condition or close family member i.e., grand parent, brother, sister), then it is essential to have regular eye test.
• Encourage your child to wear glasses or contact lenses to help improve the vision immediately.
• Maintain a healthy communication channel between you and your child to make sure you are not missing on any vision related issue your child is experiencing.
• It is very important to take your children for regular eye examinations for a healthy vision.

If you are thinking, ‘how can I tell if my child has vision problems?’, then the answer is be vigilant and be updated with your child’s eye health through regular eye test. Consult an ophthalmologist for diagnosis if you find your child continuously rubbing their eyes.

Can you go blind if you have keratoconus?

NHS states that keratoconus can progress rapidly, but it does not cause blindness.

Is astigmatism and keratoconus the same?

Both astigmatism and keratoconus are related to the change in the shape of the cornea. However, these two conditions are different.

An easier way to explain the difference is:

• Normal eye (without astigmatism) is spherical in shape
• Regular astigmatism is dome shaped, principal meridians are perpendicular (90 degrees apart)
• Irregular astigmatism is shaped like a rugby ball, principal meridians are not perpendicular (sometimes caused by injuries and scarring of the cornea)

The perpendicularity of the principal meridians of the cornea determines whether the astigmatism is regular or irregular.

Please note that all people who have keratoconus have astigmatism, but not all people who have astigmatism necessarily have keratoconus.

What vision looks like with keratoconus?

In this eye condition, the person will have blurred or distorted vision because of the curvature in the cornea. The person may also have double vision while looking. Usually, the person might see hallos while looking at the bright light.