Patent ID: 7784948

Claim:
A visual acuity testing apparatus ( 100 ) which projects an image of a chart for visual acuity testing onto a screen ( 20 ), the apparatus comprising: a projection optical unit including a disk ( 4 ) whereon the chart is placed, an illumination light source ( 1 ), and variable projection lenses which include a plurality of projection lenses ( 8 , 9 ) movable in a direction of an optical axis which are moved so as to change an image-forming position and an image size of the chart image; an input unit ( 71 ) into which an installation distance which defines a distance between the screen and the visual acuity testing apparatus and a test distance which defines a distance between the screen and an examinee are inputted; a projection lens driving unit which moves the variable projection lenses based on the installation distance and the test distance inputted into the input unit; and a light intensity adjusting unit ( 70 , 71 ) which adjusts light intensity based on the installation distance and the test distance so that brightness of the chart image falls within a predetermined reference range.