Which of the following statements about defects of vision is/are CORRECT? I. For a long sighted person, close…

Analyze the question: We need to decide which of the three statements about eye defects are true.

Concept:

• Long sight (hypermetropia): The eye is too short, or the lens is too weak. Light from close objects would focus behind the retina, so nearby objects look blurred. Distant objects are seen clearly. It is corrected with a converging (convex) lens.
• Short sight (myopia): The eyeball is too long, or the lens is too strong. Light from distant objects focuses in front of the retina, so distant objects look blurred. Close objects are seen clearly. It is corrected with a diverging (concave) lens.

Check each statement:

• I. For a long sighted person, close objects appear blurred. TRUE. A long-sighted person has a far-away near point and cannot focus on close objects.
• II. For a short sighted person, distant objects appear blurred. TRUE. A short-sighted person has a limited far point.
• III. Short sight is corrected by using a pair of converging lenses. FALSE. Short sight needs diverging (concave) lenses to spread the light before it enters the eye, so the image moves back onto the retina. Converging lenses correct long sight.

Conclusion: Only statements I and II are correct.

Tip: Remember "Myopia = Minus lens". Short sight uses a minus (diverging) lens, and long sight uses a plus (converging) lens. Also, a short-sighted person sees near objects clearly, while a long-sighted person sees far objects clearly.