Certified Ophthalmic Medical Technologist (COMT) Practice Exam

In the case of a patient who requires +6.00 sphere OU in spectacle lenses, will the corresponding contact lenses have more or less plus power?

1. Less plus power

2. Equal plus power

3. More plus power

4. No plus power

The correct answer is: More plus power

When prescribing contact lenses for a patient who requires +6.00 sphere in spectacle lenses, the contact lenses will have more plus power. This is primarily due to the difference in the effective power of lenses when positioned at varying distances from the eye. Spectacle lenses sit approximately 12mm away from the cornea, while contact lenses are placed directly on the surface of the eye. The distance between the lens and the eye affects the lens power needed. To achieve the same optical effect, contact lenses must have additional plus power to compensate for their proximity to the eye. In this case, if a patient requires +6.00 sphere glasses, the equivalent contact lens prescription often ends up being a little higher than +6.00 due to this adjustment in distance. Thus, the appropriate answer is that the contact lenses will have more plus power than the spectacle lenses.