Explain the structure and function of eye and its parts in detail. Also explain myopia, hypermetropia and presbyopia.

Hypermetropia
- A condition of over-measured sight
- Commonly known as farsightedness
- Result of the visual image being focused behind the retina rather than directly on it
Causes
- Low converging power of eye lens because of weak action of ciliary muscles.
- Eyeball being too short because of which the distance between eye lens and retina decreases.
Myopia
- known as near-sightedness
- a condition of the eye where the light that comes in does not directly focus on the retina but in front of it
presbyopia
- farsightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.