What MEM value range is considered a normal lag?

What MEM value range is considered a normal lag?

• A. 0.25-0.75
• B. 0.0-0.25
• C. 0.75-1.25
• D. 1.25-1.75

Answer: (A)

MEM assesses how accurately the eyes can accommodate at near by measuring the lens power needed to make a near target appear clear. The value you read is the amount of minus lens required to neutralize the target; a positive number means the eye is not fully meeting the near demand (an accommodative lag), while a negative value would indicate over-accommodation (a lead). The normal lag is about 0.25 to 0.75 diopters, reflecting a typical, age-appropriate response. For a near target at about 40 cm (demand ~2.50 D), a MEM of 0.25–0.75 D means the actual accommodation is roughly 1.75–2.25 D, which fits normal function. Larger lags suggest accommodative inefficiency, while values near zero or negative indicate little lag or excess accommodation.

MEM assesses how accurately the eyes can accommodate at near by measuring the lens power needed to make a near target appear clear. The value you read is the amount of minus lens required to neutralize the target; a positive number means the eye is not fully meeting the near demand (an accommodative lag), while a negative value would indicate over-accommodation (a lead). The normal lag is about 0.25 to 0.75 diopters, reflecting a typical, age-appropriate response. For a near target at about 40 cm (demand ~2.50 D), a MEM of 0.25–0.75 D means the actual accommodation is roughly 1.75–2.25 D, which fits normal function. Larger lags suggest accommodative inefficiency, while values near zero or negative indicate little lag or excess accommodation.