Gradually reducing vision starting in the teens to middle age. Sudden development of corneal edema (acute corneal hydrops) can cause a sudden fall in vision, pain, redness, watering, and light-irritation (photophobia).

Etiology

Not known. There is central corneal thinning. Keratoconus is associated with Down's syndrome, atopic diseases, and mitral valve prolapse. Some authors relate the condition to chronic eye rubbing.

What is it?

There is gradual thinning and bulging of the central cornea causing irregular astigmatism which cannot be corrected with spectacles. Semi-soft (gas-permeable) lenses of a special type are useful in this condition.

Treatment

Don't rub your eyes!
RGP contact lenses when glasses can not correct vision.
Keratoplasty (corneal transplant) surgery when vision is not corrected by either lenses or glasses.
Riboflavin activated by UV-A (more information at http://www.visioncarindia.com/KERATOCONUS.htm)
For acute corneal edema (acute corneal hydrops) Please consult your ophthalmologist-
a. A cycloplegic agent
b. Hypertonic Saline (usually 5%) in the form of drops if eye is kept open, or ointment if it is to be patched.
c. Pressure bandage for upto 48 hours, following which hypertonic saline drops are used 2-3 times a day sometimes for several months.
See also Keratoconus Corneal Cross-Linkage.