Which of the following structures of the eye is responsible for color?

Appeared in: CIP Ranchi 2023

Explanation

The iris is the pigmented part of the eye that is visible externally.
Its color is determined by the amount and type of melanin pigment present in its layers, a genetically determined trait.
The iris surrounds the pupil and contains muscles that control the amount of light entering the eye, but its most defining visual characteristic is its color.

Option A: The sclera is the tough, fibrous, white outer layer of the eye. It provides structural support but has no pigment and does not determine eye color.
Option C: The retina is the light-sensitive neural layer at the back of the eye. While it contains cone cells responsible for perceiving color, it is not the structure that gives the eye its external color.
Option D: The cornea is the transparent, avascular layer at the front of the eye that covers the iris and pupil. Its function is to refract light, and its clarity is essential for vision; it is not colored.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy and physiology of the human eye, specifically the function of its major structures as background academic context rather than a clinical decision trigger.
A nurse's assessment of the eyes includes observing the color of the iris and sclera. Yellowing of the sclera (scleral icterus) can indicate jaundice and liver problems.
Changes in iris color or the appearance of spots can sometimes be associated with certain medical conditions (e.g., neurofibromatosis, Waardenburg syndrome) and warrant referral to a specialist.
Heterochromia, a condition where an individual has different colored irises or parts of an iris are different colors, is usually harmless but can sometimes be a sign of an underlying condition.

How to Approach the Question

First, read the question carefully to identify the key concept: 'structure of the eye responsible for color'.
This is a factual recall question based on knowledge of eye anatomy.
Mentally review the function of each option provided.
Sclera: The white part. Eliminate.
Iris: The colored part. This is a strong candidate.
Retina: The light-sensing part at the back, involved in seeing color, not being colored. Eliminate.

Concept Tested & Keywords

Concept Tested: Anatomy and physiology of the human eye, specifically the function of its major structures.
Stem keywords: structures of the eye, responsible for color
Lead-in keywords: Which

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E6 Anatomy Applied Ashalatha 4e p. 246-248

E6 Histology Inderbir 11e p. 157-159

Practise the full CIP Ranchi 2023

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