Which amplitude of accommodation test requires you to add the working distance (+2.50) to your findings?

Which amplitude of accommodation test requires you to add the working distance (+2.50) to your findings?

• A. Push-up test
• B. Pull-away test
• C. Minus lens test
• D. MEM

Answer: (C)

Focus on how much the eye can accommodate and how the testing distance sets a fixed baseline. In the minus lens test, you keep the target at a near, fixed distance (typically 40 cm), which inherently demands about 2.50 diopters of accommodation. You then add minus lenses until the target becomes blurry. The amount of accommodation the eye could muster is the sum of that fixed near-demand and the extra accommodation required by the minus lenses. That’s why you add the working-distance value, +2.50 D, to the minus-lens power at the point of blur to get the true amplitude. For example, if blur occurs with -3.50 D of lenses, the amplitude would be 2.50 + 3.50 = 6.00 D. The push-up and pull-away methods measure the near point directly without needing to add a fixed distance, and MEM is a retinoscopy-based estimate that doesn’t use this +2.50 adjustment.

Focus on how much the eye can accommodate and how the testing distance sets a fixed baseline. In the minus lens test, you keep the target at a near, fixed distance (typically 40 cm), which inherently demands about 2.50 diopters of accommodation. You then add minus lenses until the target becomes blurry. The amount of accommodation the eye could muster is the sum of that fixed near-demand and the extra accommodation required by the minus lenses. That’s why you add the working-distance value, +2.50 D, to the minus-lens power at the point of blur to get the true amplitude. For example, if blur occurs with -3.50 D of lenses, the amplitude would be 2.50 + 3.50 = 6.00 D. The push-up and pull-away methods measure the near point directly without needing to add a fixed distance, and MEM is a retinoscopy-based estimate that doesn’t use this +2.50 adjustment.