HOWELL PHORIA CARD®によるAC/A比測定の試み

山口 知春, 長谷部 佳世子, 大久保 小百合, 高場 美貴, 志羅 美恵, 長谷部 聡, 大月 洋

doi:10.4263/jorthoptic.041f102

[Purpose] To evaluate the usefulness of the Howell phoria card^® (HPC, Cyclopean Designs) for measuring the accommodative convergence to accommodation (AC/A) ratio. [Methods] Fifty-six normal subjects in three age groups (the 20s: 29 subjects, the 30s: 15 subjects, and the 40s: 12 subjects) without ocular abnormalities except refractive error were examined. The AC/A ratio was measured under a full optical correction using the following methods: far HPC, near HPC, the far gradient method (far G), the near gradient method (near G), the alternating fixation method using a synoptophore (Synopto). Comparisons were made according to the measuring methods and the age groups. Data were analyzed using unpaired t-test, paired t-test, and analysis of variance (ANOVA). A P-value less than 0.01 was regarded as statistically significant. [Results] None of the measuring methods showed a significant difference in the AC/A ratio among the three age groups. The measuring methods for the AC/A ratios ranked in ascending order were as follows: Synopto, near HPC and near G, far HPC and far G. The AC/A ratios by far HPC and near HPC were approximately equivalent to the ratios by far G and near G, respectively. The AC/A ratio by near HPC was significantly higher than that by far HPC. The AC/A ratios by near HPC indicated that no significant dioptric differences were observed in any age group. [Conclusions] The AC/A ratios measured by the HPC were almost equivalent to those by the gradient method. Therefore, the HPC could be used as an easy method for measuring the AC/A ratio especially in patients with heterophoria.

HOWELL PHORIA CARD<SUP>®</SUP>によるAC/A比測定の試み

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