What is Cornea?
Cornea is the transparent outermost layer of the human eye. Technically speaking, the cornea is not a single layer; it’s made of five delicate membranes that are arranged one below the other. Cornea plays a major role in focusing person’s vision. Cornea is transparent and curvy in shape which helps in refracting light from any object to create its image on retina thereby enabling us to see the object clear and sharp.
As per World Health Organization corneal blindness is the fourth leading cause of blindness in India.
Common problems that affect the cornea are corneal ulcers, keratitis (inflammation of the cornea) and keratoconus (thinning and protrusion of the cornea) apart from the allergies, infections like herpes and the corneal abrasions caused by external injuries.
General symptoms of corneal disease:
- Reduced Vision
- Inability to open eyes in bright light
- Swelling of the eyelid
Treating corneal blindness is possible through corneal transplant. In this treatment, a healthy cornea is transplanted in place of a diseased cornea. Penetrating Keratoplasty where in the entire cornea is replaced with a donated cornea. Lamellar Keratoplasty where a partial part of the cornea which is diseased is replaced
Corneal transplant (Keratoplasty) can be :
- Full thickness corneal transplant surgery (known as penetrating keratoplasty) : A circular portion is removed from the centre of the diseased cornea. A matching circular area is removed from the center of a healthy, clear donor cornea, placed into position and sutured into place.
- Lamellar Keratoplasty :
a. DALK :Deep Anterior Lamellar Keratoplasty (only front layers transplanted)
b. DSAEK:Endothelial keratoplasty (only abnormal inner lining of the cornea is replaced)
What is Eye donation?
Eye donation is the donation of cornea after death which is then transplanted to corneally blind people
Who can donate eyes?
Anyone can be an Eye Donor
- People of any age
- Spectacle users
- Eye surgery patients
- Diabetics, Hypertensives
How much time does it take forretrieval of the eye after donation ?
Removal of eyes takes only 20 minutes. It does not delay funeral arrangements or disfigure the face.
What is the time gap for removal of eyes after death?
Eyes can be removed within 6-8 hours of time of death. If eyes are kept moist with wet cotton and in an air-conditioned room, a longer gap also may be acceptable
Eyes can be donated irrespective of whether the deceased had pledged his/her eyes. Decision is taken by the relatives.
Keratoconus is a progressive disorder of unknown cause that typically starts during adolescence. It is usually an inherited corneal disorder which means that approximately 50% of family members may have it. Normal pressure within the eye causes the cornea to bulge forward into an irregular cone shape.
What are the treatment options for Keratoconus?
A new non-surgical, non-invasive treatment, based on collagen cross-linking with Ultraviolet A (UVA, 365nm) and riboflavin (Vitamin B 2), a photosensitizing agent is now available. This changes the intrinsic biomechanical properties of the cornea, increasing its mechanical strength. This increase in corneal strength has shown to arrest the progression of keratoconus.
The treatment is performed in operation theatre under completely sterile conditions. Usually, one eye is treated in one sitting. The treatment is performed using anaesthetic eye drops. The surface of the eye (cornea) is treated with application of Riboflavin eye drops for 30 minutes. The eye is then exposed to UVA light for 30 minutes. Hence, the treatment takes about an hour per eye. After the treatment, antibiotic eye drops are applied; a bandage contact lens may be applied, which will be removed during the follow-up visit.
However one needs to understand that Collagen cross-linking treatment is not a cure for keratoconus, rather, it aims to slow the progression of the condition. However, following the cross-linking treatment, it makes the patient more comfortable to wear contact lens. The main aim of this treatment is to arrest progression of keratoconus, and thereby prevent further deterioration in vision and the need for corneal transplantation.
Diagnostic: Pachymetry, Keratometry, Topography