Visual Defects

Question 1

Short-sightedness

Answer 1

Myopia. This occurs when a person can read and see close objects clearly but distant objects are blurred. Caused by: an eyeball that is too long or, the cornea or lens being too convex. This results in light rays converging to form an image in front of the retina
Remedy: to wear concave lenses that diverge light rays before they enter the eye

Question 2

Long- sightedness

Answer 2

Hypermetropia. This occurs when a person can see distant objects but not close by. This caused by: an eyeball that is too short or, the curvature of the lens or cornea being too flat. It results in light rays converging to form an image behind the retina.
Remedy: to wear convex lenses that converge light rays before they enter the eye so that they form an image on the retina and not behind it.

Question 3

Astigmatism

Answer 3

Astigmatism may be caused by an irregularly shaped:

• cornea - corneal astigmatism, the cornea is shaped more like an oblong rugby ball than a spherical soccer ball.
• lens - lenticular astigmatism

Astigmatisms are usually hereditary but the cornea may be scarred by an injury, eye surgery or keratoconus. Can usually be corrected with spectacles, soft contact lenses or refractive laser eye surgery.

Question 4

Cataracts

Answer 4

Some of the protein may clump together and start to cloud a small area of the lens.
Diagnosed by:
- a vision test
- by examination of the eye itself that could reveal a colour change of the lens.
How can cataracts be treated:
- a local anaesthetic is used
- a small cut is mad directly into the eye
- the clouded lens is shattered by ultra sound and then suctioned out of the lens capsule
- the new clear, plastic, artificial lens is rolled up and inserted into the lens capsule where it unrolls
- the surgical opening is then closed