Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What formula is used to calculate the location of images, objects, and power of lenses?

1. Power equation: P = 1/f

2. Vergence equation: U + P = V

3. Distance formula: d = rt

4. Lens equation: 1/f = 1/do + 1/di

The correct answer is: Vergence equation: U + P = V

The lens equation, which is expressed as 1/f = 1/do + 1/di, is fundamental in optics for determining the relationships between the object distance (do), image distance (di), and the focal length (f) of a lens. This equation allows one to find the precise location of images formed by lenses, making it essential in both theoretical and practical applications in ophthalmology. In this context, the focal length is a critical parameter, as it determines how the lens will bend light rays to focus them at a particular point—essential for assessing visual acuity and ensuring correct lens prescriptions. By using this formula, practitioners can determine whether the image formed is real or virtual and can adjust the lens accordingly to achieve the desired optical effect. While the vergence equation (U + P = V) is also relevant in describing the behavior of light rays as they traverse through various media, it does not directly calculate the image and object distances related to lens systems in the same way as the lens equation. The power equation, P = 1/f, relates to the power of the lens but does not provide the necessary relationships between object distance and image distance. The distance formula, d = rt, is more applicable to linear motion and does