Cornea and External Diseases in Thailand

The cornea is the outermost, transparent, dome-shaped layer, which covers the pupil and iris in the front of the eye. The corneal tissue has five basic layers: endothelium, stroma, epithelium, Descemet's membrane and Bowman's layer. Though the cornea is clear, it has a highly structured group of proteins and cells. Contrary to most tissues in the body, the cornea has no blood vessels to protect or nourish against infection. Rather, the cornea gets its nutrients from the aqueous humor and tears, which fill the chamber behind it.

• First, together with the tear film, sclera (white section of the eye), eyelid, and the eye socket, the cornea protects the eye from germs, dirt, along with other hazardous matter.
• Second, as the outermost lens of the eye, it is the point of entry for light into the eye. When light hits the cornea, it refracts or bends the incoming light onto the lens. The lens additionally refocuses the light onto the retina, a light-sensing layer of cells of light-sensing lining the back of the eye.

To see well, the lens and cornea have to focus the light rays accurately on the retina. This refractive procedure resembles the way a camera captures an image. The lens and cornea in the eye function as would the lens of a camera. The retina estimates the film. If the cornea fails to focus the light correctly, then the retina gets a blurry image.

Some trauma, which includes blunt trauma, projectile foreign bodies, and lacerations, may result in scarring, which clouds the cornea. Hereditary problems, which include dystrophies and degenerations, might as well cloud the cornea. The commonest hereditary ailment seen in young people is keratoconus, an ailment where the cornea assumes a cone shape. This is popular in kids with Down’s syndrome as well as in people with allergic conjunctivitis. These patients might be able to use glasses or contact lenses for some time; however, might ultimately develop high astigmatism and scarring, which can't be rectified without corneal transplantation.

Sometimes, it might be essential to carry out a corneal transplant following cataract operation, if bullous keratopathy takes place. Bullous keratopathy is a disorder where the endothelial cells on the back of the cornea decline in number after a cataract operation. But this is less popular nowadays due to improved lens designs and new techniques.

The surface of the eye may be seriously damaged by several problems, which include:

• Thermal and chemical injuries
• Pathological illnesses like pemphigoid and Stevens-Johnson syndrome
• Inflammations and chronic infections
• New tissue growths like tumors and ptergium (believed to be linked to sun damage)
• Neurotrophic problems (because of damage to the eye’s sensory nerves)
• Uncommon hereditary situations like aniridia (congenital lack of the iris)

These problems may lead to extensive damage on the eye surface, resulting in scarring and new blood vessel formation; damage that leads to loss of vision.

Bascom Palmer scientists are assessing the potential of common tears for modulating promoting and modulating the healing of these conditions. A complete understanding of the correct role of tears in the healing process must result in strategies, which would quicken visual recovery and boost the percentage of patients totally pleased after the operation.