The Union Ministry of Health and Family Welfare recently amended the Transplantation of Human Organs and Tissues (Amendment) Rules, 2025, to boost cornea donation and transplant services across the country.

About Cornea

The cornea is the transparent, dome-shaped outermost layer at the front of the eye that serves as both a protective barrier and the eye's primary focusing lens. It provides approximately two-thirds of the eye's total focusing power, bending (refracting) light to form a sharp image on the retina. 

Structure

The cornea is a highly organized and avascular (lacking blood vessels) tissue, which is essential for its transparency. It is composed of multiple distinct layers that work in harmony: 

• Epithelium: The outermost layer acts as the eye's first line of defense against dust, germs, and other foreign materials. It contains thousands of tiny nerve endings, making it extremely sensitive to pain, which triggers protective reflexes like blinking. It also absorbs oxygen and nutrients from tears.
• Bowman's Layer: A tough, thin layer of collagen fibers located beneath the epithelium, providing structural strength and helping the cornea maintain its shape. Damage to this layer can result in permanent scarring.
• Stroma: The thickest layer (about 90% of the cornea) is composed of regularly arranged collagen fibers and water. This precise arrangement is crucial for the cornea's transparency and strength.
• Descemet's Membrane: A thin but strong and elastic protective barrier that lies beneath the stroma. It regenerates easily after injury.
• Endothelium: The innermost layer consists of a single layer of cells responsible for pumping excess fluid out of the stroma to prevent swelling (edema) and maintain clarity. Endothelial cells do not regenerate easily in adults, so their preservation is vital for long-term eye health.
• Dua's Layer (Pre-Descemet's layer): A recently identified layer of robust collagen found between the stroma and Descemet's membrane, which provides additional strength. 

Function

The cornea's two essential functions are:

• Refraction: It bends incoming light rays to help them focus precisely onto the retina, which converts the light into electrical signals sent to the brain for interpretation as images.
• Protection: It shields the inner, more delicate parts of the eye from environmental threats and filters out some harmful UV light wavelengths. 

Common Conditions and Treatments

Various conditions can affect the cornea, often causing symptoms such as pain, blurred vision, redness, and light sensitivity. 

• Keratitis: Inflammation, often caused by infections (bacterial, viral, fungal, or parasitic), particularly common among contact lens wearers.
• Corneal Abrasions/Ulcers: Scratches or sores on the surface that can become infected if not treated promptly.
• Keratoconus: A progressive disorder where the cornea thins and bulges outward into a cone shape, causing distorted vision.
• Corneal Dystrophies: A group of often inherited diseases that cause cloudy material to build up in one or more layers, leading to vision loss.
• Dry Eye Syndrome: Occurs when the eyes do not produce enough tears, leading to irritation and potential surface damage. 

Treatments range from prescription eye drops, gels, and special contact lenses to advanced procedures such as laser treatment (phototherapeutic keratectomy, or PTK), corneal cross-linking, and, in severe cases, corneal transplant surgery using donor tissue or an artificial cornea. 

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