Color Vision Testing — Complete User Guide

Color Vision Basics

Color vision is mediated by three types of cone photoreceptors in the retina: L cones (long wavelength/red), M cones (medium wavelength/green), and S cones (short wavelength/blue). Color vision deficiency occurs when one or more cone types are abnormal or missing.

Types of Color Vision Deficiency

Congenital (Genetic)

• Protanopia: L cone missing (red blindness), ~1% of males
• Deuteranopia: M cone missing (green blindness), ~1% of males
• Tritanopia: S cone missing (blue-yellow blindness), rare
• X-linked recessive inheritance; predominantly affects males

Acquired

• Can affect any cone type
• Often progressive and asymmetric between eyes
• May indicate underlying retinal or optic nerve disease

Testing Methods

Ishihara Plates

Quick screening test; numbers or paths visible only to normal color vision within colored dots.

Farnsworth D-15 Test

Arrangement test; more detailed classification of color deficiency type and severity.

Clinical Significance

• Congenital deficiency: Usually stable, affects both eyes symmetrically
• Acquired deficiency: Requires investigation for underlying cause
• May affect career choices (aviation, electrical work, certain medical specialties)

References

• Sharpe LT, et al. Violations of color vision norms. Prog Retin Eye Res. 1999.
• Simunovic MP. Color vision deficiency. Eye. 2010.