Evans Letter Contrast Test (ELCT) Sku(s): 500330 (Set), 500331 (Chart 1), 500332 (Chart 2) Description: The Evans Letter Contrast Test (ELCT) chart is the first standardized test for letter contrast sensitivity. The ELCT chart is designed to be used with either the ESV3000 or ESC2000 providing consistent lighting for improved testing results. The ELCT chart presents Sloan Letters optotypes line size of 20/630 with a testing distance of 1m. The varying contrast in sets of 3 letters of equal contrast level. All triplets are balanced for letter difficulty and differ in contrast by 0.15 log contrast step. ELCT Chart 1 contains 12 contrast levels ranging from standard 100% acuity to 1.65 log contrast or 2.24% contrast level. Studies show that 1.65 log contrast is the average letter contrast sensitivity for the normal older population. (Weber contrast calculation). ELCT Chart 2 presents 4 contrast levels from 1.8 to 2.25 log contrast. Set includes both Chart 1 and Chart 2.