The Inferior, Superior, Temporal Rim Width Pattern (IST Rule) Detects Glaucoma in a Japanese Population.

PRCIS

The inferior>superior>temporal rim width rate (IST pattern) rather than inferior≥superior≥nasal≥temporal (ISNT) pattern was suited for screening glaucoma in Japanese subjects. Failure of the IST pattern was associated with several important risk factors for glaucoma.

PURPOSE

The purpose of this study was to find a rim width rate pattern to yield the highest positive likelihood ratio (LR+) in detecting glaucoma eyes and to identify risk factors for glaucoma correlating with its failure in a population-based setting.

METHODS

Disc stereophotographs of 2474 eyes of 2474 normal subjects and 237 eyes of 237 glaucoma subjects found in the Kumejima Study were analyzed using computer-assisted planimetry. Among all combinations of the inferior (I), superior (S), nasal (N) and/or temporal (T) rim width rate, a pattern showing the highest LR+ was selected and risk factors for glaucoma correlating with its failure were determined using multiple logistic regression analysis.

RESULTS

The average I, S, N, and T rim widths (SD) were 0.45 (0.10), 0.39 (0.09), 0.47 (0.11), and 0.27 (0.07) mm. Among all combinations, the I>S>T rim width rate pattern (IST pattern) disregarding the N rim width showed the highest LR+ of 2.002 (95% confidence interval, 1.778-2.253). Failure of the IST pattern in normal eyes correlated with a smaller disc area (PS>T rim width pattern, the IST pattern, yielded the highest LR+ in detecting glaucoma in Japanese glaucoma eyes and its failure of or compliance with the pattern significantly correlated with several known risk factors for glaucoma.