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Purpose <p>To quantify accommodation-related bias in objective refraction measured at 3&#xa0;m, 5&#xa0;m, and an optical 5&#xa0;m space-saving chart (SSC) relative to a 20&#xa0;m reference, and to evaluate simple distance-specific corrections to obtain 20&#xa0;m-equivalent values.</p> Methods <p>Eighteen healthy adults with myopia (20–29 years; right eyes) underwent open-field autorefractor measurements (WAM-5500). At 20&#xa0;m, over-refraction was performed in 0.05 diopter (D) increments, adjusting the sphere/cylinder values as close to 0.00 D as possible. Refraction was recorded at 5&#xa0;m, 3&#xa0;m, and optical 5&#xa0;m (SSC-370) in a randomized order. Ten readings per condition were averaged. The primary outcome was spherical equivalent (SE). Bland–Altman bias and 95% limits of agreement (LoA) were estimated; secondary analyses compared shift magnitudes among short distances.</p> Results <p>Mean (± standard deviation) SE was − 0.030 ± 0.047 D (20&#xa0;m), − 0.212 ± 0.032 D (5&#xa0;m), − 0.342 ± 0.023 D (3&#xa0;m), and − 0.225 ± 0.037 D (SSC). Myopic shifts versus 20&#xa0;m were significant (all <i>p</i> &lt; 0.001). LoA were − 0.285 to − 0.081 (5&#xa0;m), − 0.413 to − 0.211 (3&#xa0;m), and − 0.314 to − 0.077 (SSC). The 3&#xa0;m shift exceeded that of 5&#xa0;m and SSC (both <i>p</i> &lt; 0.001); the shifts at 5&#xa0;m and SSC did not differ (<i>p</i> = 0.31).</p> Conclusions <p>Shorter test distances introduce a systematic myopic bias in objective refraction, being the greatest at 3&#xa0;m; 5&#xa0;m and SSC (optical 5&#xa0;m) are comparable. Applying distance-specific constant corrections may allow practical conversion to 20&#xa0;m-equivalent values.</p>

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Effect of test distance on refraction bias at 3 m, 5 m, and optical 5 m, compared with 20 m

  • 期刊论文

  • 发表日期：

    2026年3月19日

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  • Yo Iwata

摘要

Purpose

To quantify accommodation-related bias in objective refraction measured at 3 m, 5 m, and an optical 5 m space-saving chart (SSC) relative to a 20 m reference, and to evaluate simple distance-specific corrections to obtain 20 m-equivalent values.

Methods

Eighteen healthy adults with myopia (20–29 years; right eyes) underwent open-field autorefractor measurements (WAM-5500). At 20 m, over-refraction was performed in 0.05 diopter (D) increments, adjusting the sphere/cylinder values as close to 0.00 D as possible. Refraction was recorded at 5 m, 3 m, and optical 5 m (SSC-370) in a randomized order. Ten readings per condition were averaged. The primary outcome was spherical equivalent (SE). Bland–Altman bias and 95% limits of agreement (LoA) were estimated; secondary analyses compared shift magnitudes among short distances.

Results

Mean (± standard deviation) SE was − 0.030 ± 0.047 D (20 m), − 0.212 ± 0.032 D (5 m), − 0.342 ± 0.023 D (3 m), and − 0.225 ± 0.037 D (SSC). Myopic shifts versus 20 m were significant (all p < 0.001). LoA were − 0.285 to − 0.081 (5 m), − 0.413 to − 0.211 (3 m), and − 0.314 to − 0.077 (SSC). The 3 m shift exceeded that of 5 m and SSC (both p < 0.001); the shifts at 5 m and SSC did not differ (p = 0.31).

Conclusions

Shorter test distances introduce a systematic myopic bias in objective refraction, being the greatest at 3 m; 5 m and SSC (optical 5 m) are comparable. Applying distance-specific constant corrections may allow practical conversion to 20 m-equivalent values.