Certified Ophthalmic Medical Technologist (COMT) Practice Exam

How much accommodative power is required of a patient wearing full distance correction when trying to clear an image held at 33 cm?

1. 2D

2. 3D

3. 4D

4. 5D

The correct answer is: 3D

To determine how much accommodative power is needed when a patient wearing full distance correction is trying to clear an image at 33 cm, we can utilize the concept of accommodation, which is the eye's ability to change focus from distant to near objects. The formula for calculating accommodative demand is given by the equation: Accommodative Demand (D) = 1 / (distance in meters) In this case, the distance is 33 cm, which converts to 0.33 meters. Therefore, the accommodative demand would be: 1 / 0.33 = approximately 3 diopters (D) This indicates that the patient must exert approximately 3D of accommodation to bring the image into clear focus at that distance. Full distance correction allows the patient to see distant objects clearly, and any additional accommodative power beyond the full correction is required to maintain clarity at closer distances. Given this context, the correct answer identifies that the patient indeed requires 3 diopters of accommodative power to clear an image situated at 33 cm.