A MEM result of > +1.00 D would most likely indicate a lag of accommodation.

• A. Lag
• B. Lead
• C. No difference
• D. Cannot determine

Answer: (A)

The main idea is how MEM reflects how accurately the eye’s accommodation matches the near demand. In the MEM test, you neutralize the reflex by adding lenses in front of one eye. If you need a more plus lens to achieve neutralization, that means the eye is not contracting enough to meet the near demand—it’s lagging. A positive MEM value shows this lag, and the larger the positive value, the greater the lag. So a MEM result greater than +1.00 D indicates a noticeable lag of accommodation, meaning the accommodative response is about 1 diopter or more behind the demand.

A lead of accommodation would show up as a negative MEM value, where the eye overaccommodates and the reflex neutralizes with minus lenses. If MEM is around zero, the response is well matched to the demand. “Cannot determine” would be used if the reflex couldn’t be measured reliably.