A comparison of widely used clinical contrast sensitivity tests: the relation between defocus specific contrast sensitivity and higher order aberrations.

The relation between contrast sensitivity and spherical aberration and other higher order aberrations (RMS) will be studied in young and elderly subjects without ocular pathology. Contrast sensitivity will be assessed with the use of eight different contrast sensitivity tests at optimal focus and at positive and negative defocus. These results will be related to the higher order aberrations of the eyes.

Higher order aberrations, like spherical aberration, decreases visual performance.

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Best corrected visual acuity was determined with an ETDRS chart and the spherical aberration (SA) was measured with a wavefront analyzer (WASCA version 1.26.3, Asclepion Meditec, Jena, Germany).




The contrast sensitivity is measured with two computerized tests:

1. One with vertical sine-wave gratings (1.5-12 cpd) generated on a CRT (Cambridge Research Systems, Rochester, UK; Von Bekesy tracking method);

2. The Holladay sine-wave (1.5 -18 cpd) modulated circular lines (HACSS) (M&S Technologies, Skokie, Illinois, USA), and with six contrast sensitivity chart tests:

1. Pelli Robson contrast sensitivity test;

2. low contrast ETDRS-like optotype chart 2.5%;

3. Low contrast ETDRS-like optotype chart 10%;

4. Edge contrast sensitivity test: GECKO;

5. Edge contrast sensitivity test: GECKO-100;

6. Vector Vision. Contrast sensitivity is measured in mesopic (3 cd/m2) and photopic (160 cd/m2) conditions, using only the dominant eye.

Tests were performed at optimal refractive state of the eye and at a variety of defocus situations(-2D to 2D).