Short-sightedness (Myopia) can be corrected by using a:

Appeared in: RML MAINS 2025

Explanation

Myopia, or short-sightedness, is a refractive error where parallel light rays from distant objects focus in front of the retina when the eye is at rest.
This is typically due to an eyeball that is too long or a lens system with excessive refractive power.
A concave lens is a diverging lens, meaning it spreads light rays apart.
Placing a concave lens in front of a myopic eye diverges the light rays before they enter, effectively moving the focal point backward onto the retina, which corrects the vision.

Option A: A convex lens is a converging lens that brings light rays together. It would worsen myopia by causing the light to focus even further in front of the retina.
Option C: A bifocal lens has two different prescriptions in one lens and is not the primary correction for simple myopia.
Option D: A cylindrical lens corrects for focusing errors in a specific plane, which is not the issue in simple myopia.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Correction of Refractive Errors (Myopia) as background academic context rather than a clinical decision trigger.
Nurses performing vision screenings in schools or clinics need to understand the basic principles of refractive errors to identify potential vision problems in patients and provide appropriate referrals and basic patient education.
Understanding the type of corrective lens helps in patient communication, for instance, explaining why a child might need glasses and the importance of wearing them.
What if? If a patient has both myopia for distance and presbyopia for near vision due to age, a simple concave lens is insufficient. They would require bifocal or progressive lenses, which combine corrections for both distance (myopia) and near vision (presbyopia).

How to Approach the Question

First, identify the key term in the question: 'Short-sightedness (Myopia)'.
Recall the definition and cause of myopia: It's the inability to see distant objects clearly because light focuses in front of the retina.
Consider the function of different lenses. A lens is needed to move the focal point backward.
Remember that concave lenses diverge (spread out) light, while convex lenses converge (bring together) light.
To move the focal point backward, the light rays must be diverged before entering the eye.
Therefore, a concave lens is the correct choice to correct myopia. Evaluate the options based on this reasoning.

Concept Tested & Keywords

Q617wK9f5oX-LiNQ8Sv4DH

E6 Physiology Guyton 4SAE Part 3 pp. 142-144, 143-145

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 1719-1721

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