Does an autorefractor tend to overminus or overplus patients?

Does an autorefractor tend to overminus or overplus patients?

• A. Overminus
• B. Overplus
• C. Neutral
• D. No bias

Answer: (A)

When you measure refraction with an autorefractor, the eye can still accommodate unless you control for it. In non-cycloplegic conditions, especially with younger patients, accommodation tends to pull the measurement toward more minus power. This makes the device read a more myopic (overminus) error than the truly relaxed eye has. That’s why autorefractors are prone to overminus unless accommodation is suppressed—typically by fogging the vision or using cycloplegia. In practice, clinicians confirm autorefractor results with subjective refraction and cycloplegic measurements in young patients to avoid this bias.

When you measure refraction with an autorefractor, the eye can still accommodate unless you control for it. In non-cycloplegic conditions, especially with younger patients, accommodation tends to pull the measurement toward more minus power. This makes the device read a more myopic (overminus) error than the truly relaxed eye has. That’s why autorefractors are prone to overminus unless accommodation is suppressed—typically by fogging the vision or using cycloplegia. In practice, clinicians confirm autorefractor results with subjective refraction and cycloplegic measurements in young patients to avoid this bias.