| 摘要 |
An ophthalmic refractor is constructed to judge whether a visual acuity value of a symbol with a mask is minimum or maximum among values in a selected charts, select a chart containing a symbol indicating a visual acuity value smaller than the minimum visual acuity value when the visual acuity value is judged to be minimum, and select a chart containing a symbol indicating a visual acuity value larger than the maximum visual acuity value when the visual acuity value is judged to be maximum.
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