“Most of us believe outside situations shape our attitudes when, in fact, it is our view of the situations that shape our attitudes” said, Darren L. Johnson, the American writer. But did you know that your view of situations is also governed by a shape? It is the shape of your cornea…
The cornea is a transparent dome shaped front surface of your eye. It acts as the window of the eye, allowing light to pass through to the lens. This light then goes onto the retina and then the brain to form an image. The normal surface of the cornea is smooth which allows the light rays to pass undistorted to the retina enabling the brain to perceive a clear image.
What happens when the shape of your cornea changes- The clarity of the image is lost and it may appear distorted!
Keratoconus (KC) is the condition in which the cornea thins out and slowly bulges outwards to form a cone 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. (About 14%).
Myopia (near sightedness) and irregular astigmatism (irregular curvature of the eye) occur which leads to loss of vision. Scarring of the cornea in advanced stages also plays a role.
What exactly causes KC is not known.
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).
Decreasing vision (distortions, glares, ghost images, double vision)
Increased sensitivity to glare and bright light.
Troubles with night vision.
Headache after eyestrain.
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.
A routine eye examination can diagnose KC, but the following tests also help:
Slit lamp examination
Eye Refraction Vision test
Keratometry: It measures the curvature of the cornea.
Computerised Corneal Topography: It scans and maps out the corneal surface.
• 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 irregular changes in your cornea, these contacts sit over the sclera (the white part of the eye) and vault over the cornea.
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 links between the connective tissue fibres in the cornea.
Intrastromal Rings (Intacs): Two small transparent crescent shaped 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.
Deep Anterior Lamellar Keratoplasty (DALK): This is a partial thickness corneal transplant in which the inner layer (called the endothelium) of your own cornea is preserved.
This reduces the risk of rejection associated with a full corneal transplant.
Cornea Transplant/ Keratoplasty: Here, an entire portion of your cornea is replaced with donor cornea. Recovery after keratoplasty can take up to a year and may require continuation of rigid contact lenses, but they are generally very successful.
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.