Farsightedness is corrected by using

Appeared in: MNS 2024

Explanation

Farsightedness, medically known as hyperopia, is a refractive error where light from near objects focuses at a point behind the retina.
This occurs because the eyeball is anatomically too short or the eye's lens system has too little converging power.
A convex lens is a converging lens that adds refractive power to the eye's optical system.
This added power bends the light rays more sharply, moving the focal point forward from behind the retina to directly onto the retina, resulting in a clear image.

Option A: A cylindrical lens corrects for refractive errors in a specific plane or meridian.
Option B: A bifocal lens contains two different prescriptions and is not the primary correction for simple farsightedness.
Option C: A concave lens is a diverging lens that spreads light rays apart, which would worsen farsightedness by moving the focal point even further behind the retina.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Correction of Refractive Errors: Farsightedness (Hyperopia) as background academic context rather than a clinical decision trigger.
Nurses often conduct initial vision screenings (e.g., using a Snellen chart) and must be able to recognize signs of refractive errors like squinting, headaches, or difficulty reading, prompting referral to an ophthalmologist.
Patient education is a key nursing role. Explaining the difference between farsightedness and nearsightedness and the importance of wearing prescribed corrective lenses helps ensure compliance and prevent complications like eye strain or amblyopia in children.
What if? If a patient with farsightedness also develops cataracts, simply changing their glasses prescription will not be sufficient. The cataract (clouding of the lens) requires surgical removal and implantation of an intraocular lens to restore clear vision.

How to Approach the Question

First, identify the key term in the question: 'Farsightedness'.
Recall the medical term and the underlying optical problem for farsightedness, which is hyperopia, where the image focuses behind the retina.
Think about the goal of correction: a lens is needed to increase the bending (convergence) of light to move the focal point forward onto the retina.
Analyze the function of each lens type. A convex lens converges light, while a concave lens diverges light.
Based on this, select the convex lens as the logical choice for correcting farsightedness.
Confirm your choice by eliminating the other options: cylindrical lenses are for astigmatism, bifocal for presbyopia, and concave for nearsightedness.

Concept Tested & Keywords

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

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

Practise the full MNS 2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.