The refractive error caused by the differences in the curvature of the cornea and lens is called:

Appeared in: DSSSB 13 August 2024

Explanation

Astigmatism is a refractive error characterized by an irregular curvature of the cornea or lens.
This irregularity prevents light from focusing at a single point on the retina, causing blurred or distorted vision.
The term specifically relates to the difference in curvature in various meridians of the eye, unlike myopia or hypermetropia which relate to the eye's length.

Option A: Myopia, or nearsightedness, is incorrect. This condition is typically caused by the eyeball being too long or the lens having too much refractive power, which causes distant objects to be focused in front of the retina, not due to irregular curvature.
Option B: Emmetropia is the term for normal vision, where there is no refractive error. Light from distant objects focuses perfectly on the retina without the need for accommodation.
Option D: Hypermetropia, or farsightedness, is incorrect. This condition is usually caused by the eyeball being too short or the lens having too little refractive power, causing nearby objects to be focused behind the retina.

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 should be aware that uncorrected astigmatism can cause symptoms like headaches, eye strain, and fatigue, which a patient might not immediately associate with a vision problem.
Patient education is key. A nurse can explain that astigmatism is very common and can be corrected with cylindrical lenses in glasses, toric contact lenses, or refractive surgery (like LASIK).
What if a patient has both an irregularly shaped cornea and a long eyeball? This patient would be diagnosed with myopic astigmatism, a common combination where both nearsightedness and astigmatism are present and need correction.

How to Approach the Question

First, identify the core concept of the question. The stem asks to name a specific type of refractive error.
Next, isolate the key descriptive phrase: 'differences in the curvature of the cornea and lens'.
Recall or deduce the definitions of the options provided.
Myopia and Hypermetropia relate to the length of the eyeball and where light focuses (in front of or behind the retina).
Emmetropia is the absence of refractive error (normal vision).
Astigmatism specifically relates to an irregular or uneven curvature. Match this definition to the key phrase in the question to find the correct answer.

Concept Tested & Keywords

Qj-e9vST0-etQ7hJvQvIUU

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 1720-1722

E6 Physiology Guyton 4SAE Part 3 p. 143-145

Practise the full DSSSB 13 August 2024

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