American Board of Ophthalmology (ABO) Practice Exam

To achieve the base curve for minus lenses, it is necessary to add a specific amount of plus power to estimate the appropriate curvature needed for the lens. This addition compensates for the increased curvature that comes with thicker lenses associated with myopia (nearsightedness).

In the case of a minus lens, the curvature moves in the opposite direction compared to that of a plus lens. The base curve is determined based on the lens power to ensure optimal visual effectiveness and comfort for the wearer. A common guideline is that for each diopter of spherical power in minus lenses, an addition of approximately +6.00 diopters is often used to calculate the required base curve.

The selection of +6.00 serves as a standard that balances the aesthetics (lens thickness) and optical performance (visual clarity) for negative power lenses while ensuring proper fit and alignment on the eye. This choice aligns with principles in lens design related to minimizing distortions and enhancing visual quality for myopic corrections.