A female client comes to the hospital and states to the doctor that she cannot differentiate between red & green color while playing cards and seeing blood. The disease occurs in which organ?

1. A

   Retina

2. B

   Cornea

3. C

   Sclera

4. D

   Iris

Appeared in: SGPGI Nursing Officer-2023

Explanation

• The retina is the correct answer because it is the neural tissue lining the back of the eye.
• It contains specialized photoreceptor cells known as cones, which are essential for color discrimination and fine detail.
• Red-green color blindness, as described by the client, results from a genetic defect affecting the photopigments in the red (L-type) or green (M-type) cones.
• Therefore, the pathology is located within the retina.

Why Other Options Were Wrong

• Option B: The cornea is the transparent front part of the eye that covers the iris and pupil. Its main function is to refract, or bend, light. It has no role in perceiving color.
• Option C: The sclera is the white, tough outer wall of the eyeball. Its function is purely protective and structural. It is not involved in the process of vision.
• Option D: The iris is the pigmented part of the eye that controls the size of the pupil, thereby regulating the amount of light that reaches the retina. While it gives the eye its color, it does not participate in color perception.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Anatomy and physiology of the eye, specifically the mechanism of color vision and the pathology of color blindness to guide bedside assessment, documentation, and the next nursing action.
• Red-green color blindness is an X-linked recessive trait, making it much more common in males (about 8%) than in females (less than 1%). A female can be colorblind if her father is colorblind and her mother is a carrier or is also colorblind.
• Nurses should be aware that color blindness can affect a patient's ability to read color-coded materials, such as pill identifiers, food expiration labels, or certain medical monitoring devices.
• Screening for color blindness is typically done using Ishihara plates, which contain numbers or patterns made of colored dots that are difficult for someone with color blindness to distinguish.

How to Approach the Question

• First, identify the core symptom presented in the clinical scenario: the inability to differentiate between red and green colors.
• Recognize this symptom as the hallmark of color blindness (specifically, red-green color blindness).
• Next, access your knowledge of ocular anatomy and physiology. The question asks for the specific organ where the disease process occurs.
• Systematically review the function of each option: Cornea (focusing light), Sclera (protection), Iris (controlling light entry), and Retina (light and color detection).
• Connect the function of color perception directly to the anatomical structure responsible for it, which are the cone cells located in the retina.
• Conclude that the retina is the affected organ, and eliminate the other options as they are not involved in color perception.

Concept Tested & Keywords

• Concept Tested: Anatomy and physiology of the eye, specifically the mechanism of color vision and the pathology of color blindness.
• Stem keywords: differentiate between red & green color, female client, disease, organ
• Lead-in keywords: which organ
• Clinical cues: The symptom 'cannot differentiate between red & green color' is the classic description of deuteranopia (green deficiency) or protanopia (red deficiency), the most common forms of color blindness.

Question ID

Qos6sx2LFONEX1mzp_TBvu

Copy ID

Reference Book

E6 Nursing Brunner Adult Health 3SA Vol 2 Part 1 p. 84-86

E6 Medicine Harrison 22e Part 1 p. 263-265

E6 Physiology Guyton 4SAE Part 3 p. 158-160