Certified Ophthalmic Medical Technologist (COMT) Practice Exam

Which two methods are commonly used by optical labs to achieve the desired prismatic effect?

1. Decentration and polishing

2. Decentration and grounding

3. Ground-in and decentration

4. Slotting and reshaping

The correct answer is: Ground-in and decentration

The correct answer focuses on the methods commonly used by optical labs to create a prismatic effect in lenses, which are ground-in and decentration. Ground-in refers to a process where the prism is incorporated into the lens by grinding specific angles into the lens surfaces, allowing for the precise amount of prism needed for optimal visual performance. This process fundamentally alters the shape of the lens to create the desired prismatic effect, directly influencing how light is refracted through the lens. Decentration is another critical method where the optical center of the lens is intentionally shifted from the geometric center of the frame. By decentering the lens, the light entering the eye is redirected, thereby generating a prismatic effect without requiring extensive grinding of the lens surface. This adjustment allows for fine-tuning of the optical properties of the lens to enhance visual acuity and comfort for the wearer. Together, these two methods enable optical labs to customize lenses effectively, ensuring that they meet the specific visual needs of patients requiring prism correction. The combination of grinding in the precise shape and decentering appropriately provides flexibility in achieving a range of prismatic effects.