| 摘要 |
A device for testing vision potential of humans comprises an enclosure containing two transparent areas through one surface, two pairs of rollers, means for turning one of the rollers, a length of material fitted around the two pairs of rollers in snug engagement therewith so that by operating the means for turning one of the rollers the material moves around the two pairs of rollers, said material having a series of vision testing lines of indicia sized to test visual acuity from 20/20 to 20/200, each of said lines being visible in one area and each of said lines having on the material and visible through the other area markings from 20/20 to 20/200. Two sources of illumination are disposed within the enclosure, one illumination source being disposed in a position to illuminate the line of indicia and the other being positioned to illuminate the series of numbers from 20/20 to 20/200. Means for providing sufficient energy to the illumination means to enable them to provide illumination and means for positioning the person to be tested at the desired from the device are provided. The device has particular applicability for determining the vision potential of humans having a cataract in one or both eyes which through utilizing a device with a pinhole through which the person to be tested views the lines of indicia one can accurately determine the visual acuity which will be achieved following cataract surgery.
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