View article

Purpose: To estimate incidence and progression rates of nuclear opacities in the Longitudinal Study of Cataract, an epidemiologic study of the natural history of all types of lens opacities.

Methods: The Lens Opacities Classification System III was used to assess longitudinal changes between baseline and follow-up lens photographs for the 764 Longitudinal Study of Cataract participants. Baseline data, collected until December 1988 as part of a case-control study, included color slit, retroillumination, and Scheimpflug photographs. The same data were collected by the Longitudinal Study of Cataract at four subsequent visits at yearly intervals.

Results: Among patients free of nuclear opacities at baseline, the incidence of new opacities was 6% after 2 years and 8% after 5 years of follow-up. The progression of pre-existing nuclear opacities was much higher. After 2 years, nuclear opacities had progressed in more than …