Authors:

Wilkins, A.J., Della Sala, S., Somazzi, L. & Nimmo-Smith, I.

Reference:

Year of publication:

1988

CBU number:

2148

Abstract:

The Cambridge Low Contrast Gratings provide a simple, inexpensive but reliable measure of contrast sensitivity at a spatial frequency close to that at which the normal human visual system is maximally sensitive. The range of contrasts is sufficient to avoid ceiling and floor effects with normal observers and with patients, and the change in contrast from one grating to the next is small enough to avoid spuriously high or low estimates of contrast threshold. Test scores show consistency from one laboratory to another. The test takes less than 5 minutes to administer, but it commonly reveals deficits present in diabetes, multiple sclerosis, optic neuritis and glaucoma amongst patients who have normal Snellen letter acuity. The incidence of these deficits is higher in young patients than in the middle-aged or elderly. From the twenties onwards, contrast sensitivity scores for the normal population decline with age by about 10% for each decade of life. The average decline over the life span is similar to the range of sensitivity within the normal population at any given age.