The apparatus for measuring differences in the transmission of light through a lens of an eye is an eye chart has two main sections including a test section that displays a shade of a test color and a reference section that displays either a spectrum of shades, or a different shade of, the test color. The chart is displayed in a box, projected on a wall or displayed as a chart hung on a wall. The chart is illuminated using a constant or variable intensity light source. A patient is required to find or make a match between the shades disposed on the chart. When the variable intensity light is used, the patient will be required to adjust the light intensity of the section it illuminates until a match in color shades is made. The chart may be used in conjunction with a Snellen eye chart.