The duochrome test is a subjective refraction technique used in ophthalmology and optometry to refine the spherical endpoint of a patient’s prescription. It works by utilizing the principle of chromatic aberration, where different colors of light are refracted differently by the eye’s optics.
How it works:
- Red and Green Filters: The test involves presenting the patient with two colors, typically red and green, which are focused at slightly different points due to chromatic aberration.
- Comparing Clarity: The patient is asked to compare the clarity of letters or symbols on both the red and green backgrounds.
- Adjusting the Prescription: Based on the patient’s responses, the practitioner adjusts the spherical power to achieve equal clarity between the two colors.
Purpose:
- Refine Spherical Correction: The duochrome test helps fine-tune the spherical component of a prescription, ensuring the most accurate correction for nearsightedness or farsightedness.
- Confirm Endpoint: It can confirm the endpoint of a subjective refraction, providing additional assurance in the final prescription.
The duochrome test is a valuable tool in clinical practice, particularly for patients with high visual demands or those requiring precise corrections.
