MEASURED CHANGES IN CATARACT OVER 6 MONTHS - SENSITIVITY OF THE NIDEKEAS-1000

Lens opacities in 98 eyes from 63 consecutive outpatients with catarac t were recorded by both retroillumination and Scheimpflug slit methods by one operator. This was repeated at 26 +/- weeks. Image analysis us ed the EAS-1000 software. Cortical and posterior subcapsular (PSC) cat aracts were measured in retroillumination images as density more than 14 cct units below background density. Linear densitometry of white sc attered light along the optical axis was measured for slit images by b oth peak density and mean density ('area under the curve'). Retroillum ination images showed no discernible change over 6 months (the regress ion coefficient being as for the intersession reliability). Half of th e Scheimpflug slit images could not be analysed because overlying cort ical changes masked the more posterior parts of the lens. The other 49 eyes showed a significant increase in nuclear white scatter after 6 m onths, with greater degrees of change occurring in those eyes with the greatest amount of nuclear cataract initially. This is reflected by t he decreased intraclass correlation coefficient (R = 0.42). The area o f lens showing greatest change was the anterior fetal nucleus. The Nid ek EAS-1000 is able to detect changes over a 6-month period in nuclear density but not in cortical or PSC cataract. The rate of progression of nuclear white scatter increases as the lens opacity becomes more de nse. The ability to detect change in cataract over 6 months has implic ations for epidemiological studies and for trials of anti-cataract dru gs.