Abstract
Purpose: :
Parapapillary atrophy (PPA) progression has been associated with progressive glaucoma but has proven to be difficult to assess clinically. We compared intra- and interobserver agreement using a novel automated alternation flicker technology to side- by- side digital photograph inspection for the evaluation of PPA progression.
Methods: :
Consecutive patients with serial digital optic nerve photographs at least 1 year apart were included. Two graders (NR, BV) masked to photograph chronology assessed a set of photographs for progressive PPA using predefined criteria based on reference photographs containing mild, moderate, extensive or no PPA progression. At a separate session, the graders evaluated photos using alternation flicker (EyeIC, Narberth, PA) applying the same criteria. The order of patients and technique was randomized. Graders then assessed the same set of flickers and photos a second time with the order of presentation reversed. The main outcome measure was the number of quadrants of progressive PPA as identified by alternation flicker and stereophotography inspection. Inter- and intraobserver agreement using each technique were assessed using the weighted kappa statistic. A bootstrap method for comparing correlated kappa coefficients was used to assess statistical significance.
Results: :
Serial photographs from 131 eyes of 68 patients were evaluated. Both graders identified significantly more cases of PPA progression using flicker compared to photography (27-34% vs. 8-13%; both p≤0.003). The mean number of progressive quadrants identified by each grader was also larger using flicker (both p<0.05). Interobserver agreement was moderate (kappa=0.45) and significantly better (p=0.01) using flicker than photographs, which showed poor agreement (kappa=0.15). Intraobserver agreement was similar for both graders (photos: grader 1 kappa=0.53 vs. grader 2 kappa=0.52, p=0.92; flicker: grader 1 kappa=0.58 vs. grader 2 kappa=0.69, p=0.22).
Conclusions: :
Flicker identified more cases of progressive PPA than photographic review. Agreement between observers was significantly higher when using the automated flicker technology.
Keywords: optic nerve • imaging/image analysis: clinical