Abstract
Abstract: :
Purpose: To determine the ability of a new disc staging scale, the Disc Damage Likelihood Scale (DDLS), to detect changes in the appearance of sequential stereo optic disc photographs. Method: Interpretable stereo disc photos (47 cases, 83 eyes) from patients enrolled in the AGIS and CIGTS studies at Wills Eye Hospital were reviewed in a retrospective manner. All cases had baseline and follow-up photos with a minimum of a five-year interval. One glaucoma specialist and two glaucoma fellows were masked to the chronological sequence of the photos and independently determined if the two pairs of photos showed «change» (glaucomatous deterioration or improvement) or «no change» as determined by clinical impression based on features such as neuroretinal rim width, disc hemorrhages, nerve fiber layer defects, peripapillary atrophy, rim color and alterations in the vasculature. Agreement of two of three observers was used to determine the gold standard of «change» or «no change.» The stereo pairs were then shuffled and presented to three different glaucoma specialists who independently evaluated each pair to determine the DDLS stage, the vertical and horizontal cup/disc ratios and the overall cup/disc ratio. Optic nerve diameter was assumed to be average. A difference of one or more DDLS stage, or ≷ 0.1 cup/disc ratio was defined as change between baseline and follow-up photos. Agreement of 2 of the 3 specialists was used to classify the photos as showing «change» (glaucomatous deterioration or improvement) or «no change.» Percent agreement between the specialists and the gold standard was tabulated and the sensitivity and specificity of the four disc grading scales was determined. Results: The percent of exact «change» agreements between the specialists and the gold standard was 57%, 62%, 67% and 57% for the DDLS, the vertical and horizontal cup/disc ratio and the overall cup/disc ratio respectively. The percent of exact «no change» agreements was 79%, 57%, 45% and 64% respectively. The sensitivity of detecting «change» was 58%, 67%, 78% and 61% for the DDLS, the vertical and horizontal cup/disc ratio and overall cup/disc ratio respectively, and specificity values were 80%, 71%, 62% and 74%. Conclusion: The DDLS is less sensitive, but more specific, than the cup/disc ratio staging scale in detecting either glaucomatous deterioration or improvement on sequential stereo optic disc photographs.
Keywords: 498 optic disc • 359 clinical research methodology • 356 clinical (human) or epidemiologic studies: systems/equipment/techniques