Normative contrast sensitivity values for the back-lit Melbourne Edge Test and the effect of visual impairment.

Background: The Melbourne Edge Test (MET) is a portable forced-choice edge detection contrast sensitivity (CS) test. The original externally illuminated paper test has been superseded by a backlit version. The aim of this study was to establish normative values for age and to assess change with visual impairment.

Method: The MET was administered to 168 people with normal vision (18-93 years old) and 93 patients with visual impairment (39-97 years old). Distance visual acuity (VA) was measured with a log MAR chart.

Results: In those eyes without disease, MET CS was stable until the age of 50 years (23.8 +/- 0.7 dB) after which it decreased at a rate of approximately 1.5 dB per decade. Compared with normative values, people with low vision were found to have significantly reduced CS, which could not be totally accounted for by reduced VA.

Conclusions: The MET provides a quick and easy measure of CS, which highlights a reduction in visual function that may not be detectable using VA measurements.