Concept:Accommodation is the ability of the eye lens to change shape and focus on objects at different distances.
Loss of this ability is an age-related refractive defect.
Explanation:The eye normally adjusts its lens shape to focus clearly on near and distant objects.
When the lens loses this adjusting ability, the eye cannot accommodate properly.
This condition commonly occurs with aging and is known as presbyopia.
Short sightedness, or myopia, occurs when distant objects are focused in front of the retina.
Long sightedness, or hypermetropia, occurs when near objects are focused behind the retina.
Astigmatism is caused by an irregular curvature of the cornea, not by loss of accommodation.
Hence, presbyopia is the defect that specifically means loss of the power of accommodation.
Answer:B. Presbyopia