What are the causes of the following defects of vision and how can they be corrected ?(a) Cataract(b) Presbyopia

(a) Cataract: A cataract is caused by the clouding of the lens in the eye, which leads to a decrease in vision. This can occur due to aging, long-term exposure to sunlight, exposure to radiation, or it can be present at birth. Certain diseases, such as diabetes, or behaviors, like smoking and alcohol use, can also increase the risk of cataracts.

Correction: Cataracts can be corrected through surgery. The cloudy lens is removed and replaced with an artificial lens. This surgery is generally safe and effective, restoring vision.

(b) Presbyopia: Presbyopia is caused by the loss of elasticity of the lens of the eye, usually due to aging. As the lens becomes less flexible, it becomes more difficult for the eye to focus on close objects.

Correction: Presbyopia can be corrected with prescription glasses, contact lenses, or surgery. Reading glasses or bifocals (glasses with two distinct optical powers) are common solutions. Certain types of contact lenses can also provide better close-up vision. Surgical options include procedures to improve the eye's focus or to insert corrective lenses.