Keratoconus is a disorder of the eye that results in progressive thinning of the cornea. This results in gradual bulging of the cornea outward. As the name implies, ‘Kerato’ means cornea, ‘Conus’ means cone, the condition results in conical protrusion of the cornea. Keratoconus usually affects both eyes, though it often affects one eye more than the other.
The cause of Keratoconus is usually unknown although genetic and environmental factors are involved, The risk factors for developing keratoconus are rubbing of eyes, history of keratoconus among family members and having certain conditions like severe allergy, retinitins pigmemtosa and few other ocular syndromes.
A cone shaped cornea causes blurry vision and it may cause light sensitivity and glare. There is a need for frequent change of spectacle prescription due to irregular curvature of the cornea leading to myopia and irregular astigmatism. These symptoms usually occur in early teens, which may progress slowly. In very small number of cases, cornea will swell up and cause sudden significant drop in vision.
This condition can be diagnosed through a routine examination. Additional investigations include computer assisted detailed mapping of the curvature of the cornea, which gives us the diagnosis at a very early stage.
During the initial stages (forme fruste keratoconus ) corrective glasses are sufficient. Soft toric lenses or rigid gas permeable lenses can also be dispensed. Newer designs of contact lenses like Rose-K and Semi scleral lenses provide clear vision for patients with keratoconus. Some may treatment to strengthen the cornea by cross linking. Collagen cross linking with Riboflavin drops and UV light (CXL / C3R) stiffens the corneal tissue and thus halts progressive corneal thinning.
Refractive surgery cannot be performed in patients with Keratoconus. Excimer laser photo therapeutic keratectomy (PTK) is a procedure that is successfully used in management of keratoconus. Transepithelial PTK uses an excimer laser ablation in order to remove the outer corneal epithelium and smooth the anterior irregular cornea. This procedure followed by CXL improves visual outcome.
INTACS (Intrastromal corneal ring segments) are two small plastics crescents that are placed into channels created by the femto second laser within the layers of the cornea. The structural support provided will help create more regular surface closer to its original shape, which allows us to comfortably fit glasses or glasses to achieve optimal vision.
In advanced cases, Deep Anterior Lamellar Keratoplasty (DALK) allows good visual recovery. A full thickness corneal transplant is warranted when the cornea becomes extremely thin or scarred.