Question

Describe briefly the common eye disorders.

Answer 1

1. Myopia or short-sightedness: A person can see nearby objects clearly but distant objects appear blurred. The image of a distant object forms in front of the retina. It is corrected with a suitable concave lens.
2. Hypermetropia or hyperopia: A person can see distant objects clearly but has difficulty seeing nearby objects. The image of a nearby object forms behind the retina. It is corrected with a suitable convex lens.
3. Presbyopia: It is an age-related defect in which the lens loses flexibility and the ciliary muscles become weaker, making near vision difficult. It is corrected with suitable convex lenses or bifocal/progressive lenses when necessary.
4. Astigmatism: Uneven curvature of the cornea or lens causes some parts of an object to appear clear and others blurred. It is corrected with cylindrical lenses.
5. Cataract: The eye lens becomes cloudy or opaque, causing reduced or blurred vision. It is treated by surgically removing the cloudy lens and replacing it with an artificial intraocular lens.
6. Night blindness: A person has difficulty seeing in dim light because of inadequate rhodopsin in rod cells, commonly due to vitamin A deficiency. It can be prevented or treated with a vitamin-A-rich diet and medical advice.
7. Colour blindness: It is usually an inherited condition in which a person cannot distinguish certain colours, commonly red and green. There is generally no permanent corrective treatment.
8. Squint or strabismus: The two eyes do not point in the same direction because of abnormal eye-muscle action or nerve problems. It may be managed with spectacles, eye exercises or surgery.
9. Corneal opacity: Scarring makes the cornea cloudy and may impair vision severely. In serious cases, vision may be restored by corneal transplantation.
10. Conjunctivitis: Infection or inflammation of the conjunctiva causes redness, irritation and watering of the eyes. It requires appropriate medical treatment and good hygiene.