Name a common objective test used to screen for color vision deficiency in clinical practice.

• A. Snellen chart
• B. Amsler grid
• C. Visual field test
• D. Ishihara color plates

Answer: (D)

Ishihara color plates are designed to quickly check color discrimination in a clinical setting. Each plate hides a numeral or shape using dots of colors that normal color vision can pick out, while many with common red-green color vision deficiencies cannot see the embedded symbol. The plates are pseudoisochromatic, meaning they minimize reliance on brightness or lighting cues, so the result mainly reflects true color perception. This makes the test fast, inexpensive, and standardized, with well-established norms for detecting red-green color deficiencies—the most common type. Other tests you might see in eye exams assess different aspects of vision, like sharpness of vision with letters (acuity), central vision issues with an Amsler grid, or peripheral vision with a field test, but they don’t specifically screen for color vision deficiency.