Myopia is corrected by using?

Appeared in: RRB Nsg. Superintendent-21 July 2019 (Shift-2nd)

Explanation

Myopia, also known as nearsightedness, is a condition where distant objects appear blurry because the eye focuses the image in front of the retina.
This typically happens if the eyeball is too long or the cornea has too much curvature.
A concave lens is a diverging lens, which means it spreads out light rays.
Placing a concave lens in front of a myopic eye diverges the light rays just enough to move the focal point backward, ensuring the image lands precisely on the retina for clear distance vision.

Option A: A cylindrical lens corrects for refractive errors in one specific plane.
Option C: A bifocal lens contains two different optical powers.
Option D: A convex lens is a converging lens, which would worsen myopia by focusing light even more strongly in front of the retina.

Visual 1: Diagram: Correction of Myopia. A two-part diagram showing (A) light from a distant object focusing in front of the retina in a myopic eye, and (B) a concave lens placed before the eye, diverging the light rays so they correctly focus on 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: Myopia as background academic context rather than a clinical decision trigger.
Nurses play a key role in vision screening in schools and communities, identifying potential refractive errors like myopia for referral to an optometrist or ophthalmologist.
Patient education is crucial. Nurses can explain the nature of myopia and the importance of wearing corrective lenses as prescribed to prevent eye strain, headaches, and safety risks (e.g., while driving).
What if? If an older adult patient has both myopia (for distance) and presbyopia (for near vision), they would not be prescribed a simple concave lens. Instead, they would likely need bifocal or progressive lenses, which incorporate the concave correction for distance and a different power for near vision.

How to Approach the Question

This is a factual recall question that tests your knowledge of common eye conditions and their treatments.
First, identify the condition mentioned in the stem: Myopia (nearsightedness).
Recall the basic optics of myopia: light focuses in front of the retina.
Consider the function of each lens type. To move the focal point backward, you need a lens that spreads out (diverges) light.
Recall that a concave lens is a diverging lens, while a convex lens is a converging lens.
Therefore, a concave lens is the correct choice to correct myopia. A useful mnemonic is 'My Cave' (Myopia is corrected by a Concave lens).

Concept Tested & Keywords

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Practise the full RRB Nsg. Superintendent-21 July 2019 (Shift-2nd)

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