INCIDENCE AND PROGRESSION OF NUCLEAR OPACITIES IN THE LONGITUDINAL-STUDY OF CATARACT

Purpose: To estimate incidence and progression rates of nuclear opacit ies in the Longitudinal Study of Cataract, an epidemiologic study of t he natural history of all types of lens opacities. Methods: The Lens O pacities Classification System III was used to assess longitudinal cha nges between baseline and follow-up lens photographs for the 764 Longi tudinal Study of Cataract participants. Baseline data, collected until December 1988 as part of a case-control study, included color slit, r etroillumination, and Scheimpflug photographs. The same data were coll ected 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 progr essed in more than one third of the patients with pre-existing opaciti es; after 5 years, almost half had progressed. Older age was significa ntly related to higher incidence of new nuclear opacities, but not to progression of pre-existing opacities. Patients with other opacity typ es had higher nuclear incidence and progression rates. Conclusions: In this clinic-based, older-patient population, new nuclear opacities de veloped in less than one tenth of the patients after 5 years of follow -up. in contrast, almost one half of the patients with pre-existing op acities had worsened after 5 years. These estimated rates can be used to plan intervention or other studies of nuclear changes in similar po pulations.