ASSESSMENT OF OBSERVER VARIABILITY IN THE CLASSIFICATION OF HUMAN CATARACTS

  • 1 January 1982
    • journal article
    • research article
    • Vol. 55  (2) , 81-88
Abstract
An in vitro cataract classification system was developed and used to demonstrate a relationship between sustained aspirin intake and the apparent deceleration or retardation of human cataract formation. The reliability of this cataract classification scheme was assessed. Sets of extracted human cataractous lenses, which were photographed in vitro, were randomly assigned to 5 observers. The task was to classify the lenses on the basis of nuclear and cortical involvement, as reflected in color and area changes along 5 groupings. Assessments were made on the basis of both intraobserver and interobserver agreement levels, corrected for chance (weighted .kappa. values). All 5 examiners evidenced levels of intraobserver agreement which ranged between good and excellent (0.73-0.92). The interobserver chance-corrected agreement levels ranged between fair and excellent (0.46-0.83). Each of the 5 observers was ranked on the basis of his agreement levels with the remaining 4 observers. The more experienced the observer in classifyng cataracts, the more consistent his rankings vis-a-vis the remaining 4 evaluators. These results are discussed in the general context of observer variability studies in the field of medicine.