Consider the following pairs : Condition | Result 1. If ciliary muscles are relaxed | focal length of the eye lens increases 2. If eye lens becomes thicker | enables us to see nearby objects clearly 3. For a young adult with normal vision | near point is about 25 cm How many of the above pairs are correctly matched?

Accommodation of the eye

• The ability of the eye lens to adjust its focal length is called accommodation and it is brought about by the ciliary muscles.
• When the ciliary muscles are relaxed, the lens becomes thin, its focal length increases and distant objects are seen clearly. Hence, pair 1 is correctly matched.
• When the ciliary muscles contract, the curvature of the eye lens increases, the lens becomes thicker, its focal length decreases and nearby objects can be seen clearly. Hence, pair 2 is correctly matched.
• The minimum distance at which objects can be seen most distinctly without strain is called the near point or the least distance of distinct vision, which is about 25 cm for a young adult with normal vision. Hence, pair 3 is correctly matched.
• The far point of a normal eye is infinity.