Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What method of occlusion should be used for testing visual acuity in a patient with nystagmus?

1. Use a polarizing occluder

2. Blur the non-tested eye with a high plus lens

3. Cover both eyes simultaneously

4. Use a standard black occluder

The correct answer is: Blur the non-tested eye with a high plus lens

In testing visual acuity for a patient with nystagmus, blurring the non-tested eye with a high plus lens is the most effective method. Patients with nystagmus often exhibit involuntary eye movements, which can lead to fluctuating visual acuity. By using a high plus lens, the non-tested eye's vision is intentionally blurred, minimizing any potential advantage it might provide during the assessment. This approach helps to ensure that the visual acuity measurement is accurately reflecting the capabilities of the tested eye alone, without interference from the other eye. This method also helps to stabilize the patient's visual perception, as it reduces the likelihood of the brain opting for the clearer image from the non-tested eye. As a result, the true visual acuity of the eye being tested can be evaluated more effectively. This focus on isolating the testing variables is crucial in providing an accurate assessment of the patient's vision status.