MEASUREMENT OF GLARE SUSCEPTIBILITY USING LOW-CONTRAST LETTER CHARTS

The Committee on Ophthalmic Procedures Assessment of the American Acad emy of Ophthalmology suggested either contrast sensitivity or low-cont rast visual acuity (VA) measured before and after adding a glare sourc e as a test for assessing overall visual disability from immature cata racts. We have developed a test that follows the Committee's three pri nciples of design, and we report that the effect of glare on VA is con siderably greater for recognizing low-contrast letters than for recogn izing high-contrast letters. The effect of glare on VA increases progr essively as letter contrast is reduced from 96% through 50%, 25%, 11%, and 4%. The 25% chart (and possibly the 11% chart) gives the most sui table sensitivity for eyes with immature cataracts. Neither age-relate d brunescence and aging itself nor even the presence of a distinct opa city necessarily produces high sensitivity to glare. The test is sensi tive enough to detect an ageing effect even before the age of 45 to 55 years and to reveal large intersubject differences among normally sig hted 19- to 25-year-old subjects.