Keratoconus is a progressive disease in which the cornea thins and changes shape. It can occur in almost any decade of life. This disease changes the curvature of the cornea, creating mild to severe distortion, called astigmatism, and usually nearsightedness. Keratoconus may also result in swelling and scarring of the cornea and vision loss. It can also cause significant distortions in night vision that can make night driving impossible.
Factors associated with keratoconus include:
Genetics (a person can inherit a tendency for the condition from a parent)
Eye trauma (for example, from extensive rubbing of the eyes)
Eye diseases, such as retinitis pigmentosa, retinopathy of prematurity, vernal keratoconjunctivitis
Other diseases, like Down syndrome, osteogenesis imperfecta, Addison's disease, Leber's congenital amaurosis, and Ehlers-Danlos syndrome
The main goal of treatment of keratoconus has changed over the last few years from that focused mainly on improvement of visual acuity to an array of newer modalities focused on the prevention of progression of the disease.
1. Spectacles. Reduced visual acuity due to keratoconus is initially managed with spectacles. When spectacles fail to adequately correct visual acuity, contact lenses are the next option.
2. Contact lenses. Contact lenses often provide better vision than spectacles by masking irregular astigmatism (higher-order aberrations).
3. Intrastromal corneal ring segments ( INTACS ): Contact lens-intolerant patients with clear central corneas may benefit from intracorneal ring segment insertion.
4. Phakic intraocular lenses ( ICL). Surgical techniques other than laser corneal refractive procedures should be considered for the correction of residual refractiveerror in the post-ICRS keratoconus patients. One alternative is the use of anterior or posterior phakic IOLs, including toric lenses, either alone or after implantation of ICRS.
5. Cornea Collagen Cross linking ( C3R): The disadvantage of the previously mentioned procedures is that none adequately prevent keratoconus progression that occurs due to the underlying biomechanical corneal changes.
6. Keratoplasty: In advanced cases of keratoconus where all the above mentioned modalities of treatment are not helpful, transplantation of the cornea needs to be done. The conical shaped cornea ( 8-8.5mm central part ) is replaced by a healthy donor tissue. Newer techniques of transplantation have come in vogue where only anterior layer or the front part of the cornea is damaged there by improving the longevity of the donor cornea in these patients ( DALK).