To solve the problem, we need to identify which among the given eye defects is primarily related to aging.
1. Understanding Presbyopia:
Presbyopia is an age-related eye condition in which the eye’s lens loses its flexibility, making it difficult to focus on close objects. It typically occurs after the age of 40 and is due to the weakening of the ciliary muscles and loss of elasticity of the eye lens.
2. Differentiating from Other Defects:
- Myopia (short-sightedness) and Hypermetropia (long-sightedness) are refractive defects but not specifically age-related.
- Colour blindness is a genetic disorder and is present from birth in most cases.
- Presbyopia, on the other hand, develops with age.
Final Answer:
The age-related eye defect is \({\text{Presbyopia}} \).