Keratoconus

What is Keratoconus?

Keratoconus (KC) is the condition in which the cornea thins out and slowly bulges outwards to form a conical, protruded shape. This cone shaped cornea also has an irregular surface which leads to blurred vision. It usually affects both the eyes.
It usually develops during teenage or early twenties. However it can occur in any age. Occasionally it may run in families.
Myopia (near sightedness) and irregular astigmatism (irregular curvature of the eye) occur which leads diminution of vision. Scarring of the cornea in advanced stages may lead to loss of vision.

What causes Keratoconus?

Risk factors include a history of eye allergies, rigid contact lens wear and vigorous rubbing of the eyes.
KC usually occurs in isolation, however sometimes, it has been found to occur in patients having connective tissue disorders, Down’s Syndrome (A condition in which the child has physical and mental developmental delay), Mitral Valve prolapse (a disease of the heart valves) and Atopic Dermatitis (a skin disease).

Do I have Keratoconus? (Signs and Symptoms)

Frequent changes in spectacle power.Decreasing vision (distortions, glares, ghost images, double vision)
Increased sensitivity to glare and bright light.
Troubles with night vision.
Headache after eyestrain.

What are the complications that could occur?

Scarring of the cornea which worsens vision.
Hydrops which occurs when one of the inner layers of the cornea splits. The fluid from the eye enters the cornea causing it to swell and become cloudy white.

What tests are needed?

A routine eye examination can diagnose KC, but the following tests are helpful
Slit lamp examination
Eye Refraction Vision test
Keratometry: It measures the curvature of the cornea.
Corneal Topography: It scans and maps out the corneal surface.

How can it be treated?

1. Lenses:

• Glasses or Soft Contact lenses can correct blurry vision in the initial stages.
• Rigid Gas Permeable Contact Lenses: These are hard contact lenses which are specially designed for KC.
• Piggyback Lenses: If you are not too comfortable with hard lenses, your doctor may “piggyback” a hard lens on top of a soft lens.
• Hybrid Lenses: Another option for those uncomfortable with hard lenses, these contacts have a soft ring on the outside with a rigid centre.
• Scleral Contact lenses: Indicated for  advanced irregular changes in your cornea, these lenses sit over the sclera (the white part of the eye)  and provide clear vision by nullifying the aberrations (optical imperfections) of the eye.

Most KC patients require frequent check-ups and changes to obtain good vision and comfort.

2. UV Crosslinking:
Here, eye drops containing Vitamin B2 are placed over the cornea and activated by UV Light. This helps to strengthen the cornea and stabilize the power of the cornea

3. Surgery:
Intrastromal Rings (Intacs): Two small transparent crescent shaped PMMA (plastic)  rings are inserted into the cornea, which helps flatten the cone and stabilise the corneal shape. You may still require to wear corrective lenses, but the surgery helps the lenses fit better and be tolerated better.
Corneal Transplant:
Deep Anterior Lamellar Keratoplasty (DALK): This is a partial thickness corneal transplant in which only the outer layers of the cornea are replaced and  the inner layer (called the endothelium) of your own cornea is preserved.
This reduces the risk of corneal graft rejection associated with a full thickness  corneal transplant.

Penetrating keratoplasty: Here full thickness of your cornea is replaced with donor cornea. Recovery after keratoplasty  takes up to 2 to 3 months  and may require continuation of rigid contact lenses, but they are generally very successful.

How can I prevent it?

Most cases aren’t preventable, but you can take the following precautions:
If you need to rub your eyes, do it as gently as possible.
Never share hard contact lenses with someone else.
Suspect an abnormality if you need a frequent change in your glass prescription or if your vision is blurred even with glasses.