ולידציה של תפקוד הרגישות לקונטרסט ב-Chart 2020
A validation of the contrast sensitivity function in the vision Chart2020

שם הסטודנטיות: מרים ביבאס ואביגאל טואיטו
שם מנחה: ד"ר רימה שבעני

Introduction: The minimum contrast required for detection is called contrast sensitivity (CS, Barten,1999). CS may help in detecting and monitoring ocular diseases (e.g. Hawkins et al., 2003; Yamane et al., 2004). The aim of this study is to test if the CS function of the Chart2020 and the MARS chart (which have good validity and repeatability, Dougherty et al., 2005) are interchangeable.
Methods: Healthy subjects, with 6/6 distance Visual Acuity (VA, Snellen), J2 Near VA (Jaeger), participated in this study. Three consecutive measurements (on the right eye only, at 50cm distance) of the MARS chart (by student A) and the Chart2020 (by student B, using the mode letters that decrease in contrast), were performed in a random order and the average and standard deviation was calculated. Measurements were performed only on the right eye, in the same room as the VA testing, with dimmed lighting for the Chart2020 test. A calibrated screen to a luminance of 85cd/2 for the Chart2020 test was used. CS results was compared with the MARS test vs the Chart2020 using Correlation, Paired T tests and Bland and Altman test (1986).
Results: 30 subjects (25 women, 5 men) between the ages of 18-35 (average age 24.85±3.25 years) participated in this study. The mean CS with the MARS was 1.78±0.014 and significantly higher than CS with Chart2020 (1.68±0.009, P <0.01). No correlation was found between the two tests (r=0.39).
Conclusions: The Mars and the Chart2020 are not interchangeable maybe because there are different CS steps between the two charts and different CS calualtion: the Chart2020 doesn’t take into account the mistakes made along the test but uses only the last level of CS seen-as the end result, unlike the MARS that takes into consideration those mistakes. Measuring CS with the Chart2020 may represent better the CS of people who work on computers daily and use smartphones