Kerato means Cornea (Front transparent portion of the eye) and Conus means cone like. As the name suggests, in keratoconus, cornea becomes distorted and has thin point protruding forward. Cornea is transparent structure which focusses light rays onto retina. If cornea becomes distorted in shape then clarity of image is lost and even object looks distorted to the eye.

WHAT IS KERATOCONUS?

Keratoconus (KC) is the condition in which the cornea becomes thin 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.

Its typical presentation in in early 20 years of age. It runs in family. Due to change in the shape of cornea, patients present with frequent change in glasses. Usually they have irregular astigmatism. Even the best corrected visual acuity is not 100 % in most of the cases. In later stages, cornea may get swollen up or scarred leading loss of vision.


WHAT CAUSES KERATOCONUS?

Exact pathogenesis of KCN is unknown.

Risk factors include a history of eye allergies, rigid contact lens wear and vigorous rubbing of the eyes.

KCN is seen in connective tissue disorders, Down’s syndrome, Mitral Valve prolapse (a disease of the heart valves) and Atopic Dermatitis (a skin disease).

SIGNS AND SYMPTOMS

1. Blurred vision (distortions, glares, haloes, ghost images, diplopia {double vision})
2. Intolerance to bright light
3. Headache after eyestrain
4. Pain in late stage

Bacterial and parasitic corneal ulcer are more common in person using contact lenses. Proper precautions should be followed during contact lens use. Viruses like herpes simplex & H. zoster can cause recurrent corneal ulcers. Fungal corneal ulcers are very common in farmers. Overuse of steroids is one of the risk factor for fungal corneal ulcer.

If left untreated, it may progress leading to Hydrops. It occurs when one of the inner layers (Endothelium) of the cornea gives way. The fluid from the eye enters the cornea. Cornea becomes oedematous and becomes white.

Keratoconus can be diagnosed by ophthalmologist by slit lamp examination, Refraction report, keratometry (it gives information about curvature of cornea) and topography (It tells about shape & thickness of cornea)

TREATMENT :

Once it is observed that KCN is progressive with the help of sequential topography reports, to stop progression of KCN, C3R is done. Full form of C3R is Corneal Collagen Cross linking with Riboflavin. It strengthen the bonds between collagen in cornea. This procedure stops progression of KCN in most of the cases.

For visual rehabilitation after C3R , patient can be advised

  • Glasses: It can correct blurred vision in the initial stages.
  • Rigid Gas Permeable Contact Lenses: These are hard contact lenses which are specially designed for KCN.
  • Scleral Contact lenses: It forms vault over cornea and its periphery is in touch with sclera. Piggybank CL & hybrid CL can be used to improve vision.


SURGERY :

Optical Keratoplasty : TIn late stage of KCN , where there is scarring over cornea, complete replacement of host cornea with cornea obtained from eye banks might be required.

Deep Anterior Lamellar Keratoplasty (DALK): This is advanced technique of corneal transplant where upper part of cornea is replaced keeping behind thin layer of patient’s cornea namely endothelium. Chances of rejection of cornea is less than that of Optical keratoplasty.

Intrastromal Rings (Intacs) : These are plastic rings implanted in the substance of cornea so that steeper cornea becomes flat and patient can have better contact lens fit thereafter. Corrective spectacles may be required after INTACS, but the surgery helps the lenses fit better and be tolerated better.

PREVENTION :

Don’t rub your eyes. If itching is intolerable, visit your ophthalmologist.

If there is frequent change in your glass number or there is blurred vision even after wearing glasses, please visit your ophthalmologist.