**Question:** Green colour blindness is called -

A. Protanomaly
B. Deuteranomaly
C. Tritanomaly
D. Achromatopsia

**Core Concept:** Color vision deficiency is a condition where the ability to perceive colors is impaired due to abnormalities in the visual pathway. There are three types of color receptors in the human eye: red, green, and blue. Color vision deficiency can be classified based on which color receptors are affected.

**Why the Correct Answer is Right:**

Green color blindness, also known as deuteranomaly, occurs when the green color receptor (M-cones) is affected. This results in difficulty distinguishing between green and other colors, making greens appear more yellowish or bluish. In this case, the correct answer is A, Protanomaly, as it refers to red color receptor (L-cones) dysfunction, which results in difficulty distinguishing between red and green colors.

**Why Each Wrong Option is Incorrect:**

Option B, Deuteranomaly, is the correct answer because it describes the situation where green color receptors are affected, leading to green color blindness. The incorrect options are as follows:

**Option C (Tritanomaly):** This refers to blue color receptor (S-cones) dysfunction and is responsible for blue color deficiency.

**Option D (Achromatopsia):** Achromatopsia is a complete color blindness caused by defects in all types of cones. In this question, we are specifically discussing green color deficiency, so Achromatopsia is not the correct answer.

**Clinical Pearl:** Color vision deficiency is a common genetic disorder with an estimated prevalence of around 8% in men and 0.5% in women. It is caused by mutations in the genes encoding the opsins (proteins) responsible for cone photopigments. Color blindness can be identified through various tests, such as Ishihara color test, Farnsworth-Munsell 100 Hue test, and heterochromia (different color of iris in each eye).

**Correct Answer Explanation:**

Green color blindness (deuteranomaly) is caused by mutations in the genes encoding the opsin proteins, specifically the red (L-cones) and green (M-cones) types. These mutations lead to a reduced sensitivity of the affected cones, making it difficult for an individual with deuteranomaly to differentiate between red, green, and yellow colors.

**Why Each Wrong Option is Incorrect:**

Option A (Protanomaly) is incorrect because it refers to red color deficiency, which is different from green color deficiency discussed here.

Option B (Deuteranomaly) is incorrect as it describes green color deficiency, while Option C (Tritanomaly) describes blue color deficiency.

Option D (Achromatopsia) is incorrect because it represents complete color blindness, which is not the case in green color deficiency (deuteranomaly).