Which of the following statements about the human eye is NOT correct?

RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Applied Physiology

Easy

Appeared in: RRB Nsg Superintendent -29 April 2025 (Shift-1st)

Explanation

This statement is factually incorrect.
The standard value for the near point, or the least distance of distinct vision, for a healthy young adult is 25 cm.
While the near point can vary, especially with age (it is closer in children and recedes in older adults), 20 cm is not the accepted standard for a young adult.

Option B: This statement is factually correct. 'Least distance of distinct vision' is another name for the near point.
Option C: This statement is factually correct. The process of accommodation, where the lens becomes more convex to focus on near objects, has a physical limit. Therefore, the focal length can only be shortened to a certain minimum.
Option D: This statement is factually correct. It provides the standard definition of the 'least distance of distinct vision.'.

Visual 1: Diagram - An illustration of the human eye showing the lens, ciliary muscles, and retina. Arrows could demonstrate how light from a near object (at 25 cm) is focused onto the retina when the lens is accommodated (more convex).
Visual 2: Chart - A simple chart showing the change in the near point distance with age (e.g., Child: ~9 cm, Young Adult: 25 cm, 50-year-old: >50 cm) to illustrate the concept of presbyopia.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiology of the human eye, specifically the concepts of near point, accommodation, and the least distance of distinct vision as background academic context rather than a clinical decision trigger.
Understanding the near point is crucial for identifying presbyopia, the age-related loss of accommodation. Nurses often encounter older patients who require reading glasses because their near point has receded, making it difficult to read medication labels or instructions.
A patient's complaint of needing to hold reading material farther away is a classic sign of presbyopia, prompting a recommendation for an eye exam.
What if the patient is a 10-year-old child? The answer would still be A, but the underlying physiology is different. A child's near point is much closer (around 9 cm) due to the high elasticity of their lens and strong power of accommodation. The 20 cm value would still be incorrect for them, but for a different reason than for a young adult.

How to Approach the Question

First, identify the negative framing of the question: you are looking for the statement that is 'NOT correct' or false.
Read each option carefully and evaluate its factual accuracy based on your knowledge of eye physiology.
Option A presents a specific numerical value (20 cm). Recall or verify the standard value for the near point in a young adult.
Options B and D are definitions. Assess if they are the correct, standard definitions for the terms used.
Option C describes a physiological limit. Consider the mechanism of accommodation to determine if this limit exists.
The statement that contains a factual error is the correct answer to this 'NOT' question.

Concept Tested & Keywords

Concept Tested: Physiology of the human eye, specifically the concepts of near point, accommodation, and the least distance of distinct vision.
Stem keywords: human eye, vision, near point, least distance of distinct vision, focal length
Lead-in keywords: NOT correct
Negative lead-in flag: The question asks for the statement that is NOT correct.

QBKtKDRO68WH7IAyUfBPqf