Plus lenses become weaker as they move toward the eye. Which choice correctly completes this statement?

Plus lenses become weaker as they move toward the eye. Which choice correctly completes this statement?

• A. Stronger
• B. Weaker
• C. No change
• D. Undefined

Answer: (B)

Vertex distance matters: how strong a plus lens seems to the eye changes with how far the lens sits from the cornea. For a positive (plus) lens, moving it toward the eye reduces the eye-ward convergence it provides, so the effective power at the cornea becomes weaker. If you move the lens away from the eye, the convergence effect is applied further from the cornea and the effective power increases (the lens appears stronger). A quick illustration: a +2.00 D lens at 5 cm from the eye has a higher effective power than the same lens moved to 2 cm from the eye (roughly 2.22 D vs about 2.08 D). Therefore, plus lenses become weaker as they move toward the eye.

Vertex distance matters: how strong a plus lens seems to the eye changes with how far the lens sits from the cornea. For a positive (plus) lens, moving it toward the eye reduces the eye-ward convergence it provides, so the effective power at the cornea becomes weaker. If you move the lens away from the eye, the convergence effect is applied further from the cornea and the effective power increases (the lens appears stronger). A quick illustration: a +2.00 D lens at 5 cm from the eye has a higher effective power than the same lens moved to 2 cm from the eye (roughly 2.22 D vs about 2.08 D). Therefore, plus lenses become weaker as they move toward the eye.