ACTIVITY 1
Read the following explanation on the various defects of vision and answer the questions at the evaluation section.
Common eye defects
- Short sightedness or myopia. It’s a condition of the eye where near objects are clear while far objects are blurred (not clear ). The eyeball is too large for the and this makes images of far objects to be formed infront of the Retina. The defect is corrected by placing a concave lens in front of the eye.
2. Long sightedness or hypermetropia. It's a condition of the eye where far images are clear while near objects are not clear. Images are formed beyond the retina. The defect is corrected by placing a convex lens infront of the eye.
3. Presbyopia – this is the inability of the eye to accommodate and this occurs as the eye ages due to the weakening of the ciliary muscles. It can be corrected by the use a pair of spectacles.
4.Astigmatism – this is a defect where the eye has two different focal lengths as a result of the cornea not being spherical. Corrected by the use of cylindrical lens.
5. Colour blindness– caused by deficiency of colour detecting cells in the retina.
ACTIVITY 2
Watch the clip below on the various defects of vision and answer the questions at the Evaluation section.