Which term describes the sign of diopter power used to correct hyperopia?

• A. Plus power
• B. Minus power
• C. Zero power
• D. Double power

Answer: (A)

The sign indicates whether the corrective lens converges (positive) or diverges (negative) light. For hyperopia, the eye currently focuses images behind the retina, so you need lenses that converge light to move the focal point forward onto the retina. This is done with convex lenses, which have positive diopter values. Therefore, the term describing the sign of diopter power used to correct hyperopia is plus power. Negative power would correct myopia by diverging light, zero power would provide no correction, and double power isn’t a standard term. In prescriptions you’ll often see a plus sign, like +2.50 D, indicating plus power.