A patient has 20/100 vision at 10 feet. What lenses would you show over the trial frame during the refraction?

A patient has 20/100 vision at 10 feet. What lenses would you show over the trial frame during the refraction?

• A. +2.00, -2.00
• B. +1.00, -1.00
• C. +0.50, -0.50
• D. +1.50, -1.50

Answer: (B)

The main idea here is to choose a safe, informative starting defocus for a patient with reduced distance vision during refraction. When a patient’s acuity is poor, you want to test for a refractive error without pushing accommodation too hard or making the image excessively blurry. Using lenses with equal magnitude but opposite signs provides a balanced way to probe how the eye responds to defocus in either direction while avoiding an overly large change in clarity. A moderate pair like plus 1.00 and minus 1.00 diopters is a reasonable, conservative starting step: it’s strong enough to reveal whether a refractive component is present and to help you compare improvements in clarity when defocus is added in either direction, but not so strong that it overwhelms the patient with blur or fatigue. Lenses with larger magnitudes (+2.00/-2.00 or +1.50/-1.50) would tend to induce more blur and could mask or confuse the patient’s true refractive status. A very small change like (+0.50/-0.50) might be too subtle to reveal a meaningful difference in acuity at this stage. Therefore, the moderate equal-magnitude pair is the most informative starting point for guiding subsequent refinement toward the patient’s best correction.

The main idea here is to choose a safe, informative starting defocus for a patient with reduced distance vision during refraction. When a patient’s acuity is poor, you want to test for a refractive error without pushing accommodation too hard or making the image excessively blurry. Using lenses with equal magnitude but opposite signs provides a balanced way to probe how the eye responds to defocus in either direction while avoiding an overly large change in clarity. A moderate pair like plus 1.00 and minus 1.00 diopters is a reasonable, conservative starting step: it’s strong enough to reveal whether a refractive component is present and to help you compare improvements in clarity when defocus is added in either direction, but not so strong that it overwhelms the patient with blur or fatigue.

Lenses with larger magnitudes (+2.00/-2.00 or +1.50/-1.50) would tend to induce more blur and could mask or confuse the patient’s true refractive status. A very small change like (+0.50/-0.50) might be too subtle to reveal a meaningful difference in acuity at this stage. Therefore, the moderate equal-magnitude pair is the most informative starting point for guiding subsequent refinement toward the patient’s best correction.