It is a type of refractive error in which light rays are focused in front of the retina?

Appeared in: KPSC Staff Nurse - 2017

Explanation

Myopia, also known as nearsightedness, is a refractive error where parallel light rays from distant objects are focused at a point in front of the retina.
This misalignment is typically caused by an eyeball that is too long (axial myopia) or a cornea/lens system that has too much refractive power.
The primary symptom is blurred vision for distant objects, while near vision remains relatively clear.
Correction is achieved with a concave (diverging or minus-powered) lens, which diverges the light rays, effectively moving the focal point backward onto the retina.

Option A: In hypermetropia (farsightedness), light rays from distant objects focus at a point behind the retina, not in front of it.
Option C: Metropia is not a standard term for a refractive error. The correct term for a normal eye with no refractive error, where light focuses perfectly on the retina, is Emmetropia.
Option D: In astigmatism, light rays do not come to a single focal point. Instead, they focus at multiple different points, either in front of or behind the retina, due to an irregular curvature of the cornea or lens.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Refractive errors of the eye as background academic context rather than a clinical decision trigger.
Nurses are often involved in vision screening in schools and communities, making the identification of signs of refractive errors like myopia crucial for early referral and treatment.
Uncorrected myopia in children can lead to poor academic performance and social difficulties. In adults, it can be a safety hazard, particularly when driving.
Patient education is a key nursing role, including explaining the nature of the refractive error, the importance of wearing corrective lenses as prescribed, and the need for regular eye examinations.

How to Approach the Question

Identify the core concept of the question, which is about the physics of vision and refractive errors.
Focus on the key phrase: 'focused in front of the retina'. This is the defining characteristic you need to match.
Recall the definitions of the common refractive errors:
Myopia = Nearsightedness = Focus in front of the retina.
Hypermetropia = Farsightedness = Focus behind the retina.
Astigmatism = Multiple focus points due to irregular shape.

Concept Tested & Keywords

QgZfEl0RhVsqXPS-xcFm9J

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

E6 Physiology Guyton 4SAE Part 3 p. 142-144

Practise the full KPSC Staff Nurse - 2017

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