Certified Ophthalmic Medical Technologist (COMT) Practice Exam

Which test is utilized to fine-tune a refraction using different wavelengths?

1. Duochrome test

2. Visual acuity test

3. Stereopsis test

4. Contrast sensitivity test

The correct answer is: Duochrome test

The Duochrome test is specifically designed to help fine-tune a refraction by evaluating how well a patient perceives letters against different background colors. During this test, two colors (typically red and green) are used to present a target. The principle behind the Duochrome test is based on the chromatic aberration of the eye, where different wavelengths of light are focused at slightly different points on the retina. The human eye tends to focus blue light slightly in front of the retina, while red light focuses slightly behind it. Therefore, when patients are given the option to choose between two colors, their feedback can indicate whether the current prescription is optimal or if adjustments are needed. If a patient sees the letters more clearly against one color, it suggests that the refraction may require modification to better accommodate the wavelength they are struggling with. By utilizing different wavelengths, the Duochrome test effectively allows for the fine-tuning of a refraction, which enhances overall visual acuity. Other tests mentioned, such as the visual acuity test, stereopsis test, and contrast sensitivity test, assess different aspects of visual function, but do not specifically focus on the use of different wavelengths to refine a refraction.