Concordance of flicker comparison versus side-by-side comparison in glaucoma

BackgroundFlicker comparison superimposes baseline photos of the optic nerve head to subsequent photos, alternating them at a high frequency rate to create the perception of motion showing glaucomatous structural changes over time. The primary purpose of this study was to determine the degree of concordance among examiners in judging glaucomatous progression between serial optic nerve head photos using digital image flicker comparison versus the traditional side-by-side photograph comparison method. The secondary purpose was to determine if flicker comparison was quicker than side-by-side comparison.MethodsA total of 29 eyes were selected from patient records at Nittany Eye Associates. Fourteen eyes showed various degrees of glaucomatous structural change among photos, while the remaining 15 eyes had no glaucomatous structural change. Three masked optometrists experienced in glaucoma management graded whether the photos represented glaucomatous change or no change when viewing photos randomly assigned to side-by-side or flicker comparison.ResultsAmong multiple graders, flicker comparison gave moderate agreement, whereas side-by-side analysis gave fair agreement. The difference in time between the 2 methods was not statistically significant.ConclusionsFlicker comparison is a unique, easy to learn, and an accurate way to view serial optic nerve head photographs. More study is needed to determine if flicker comparison is a useful tool in the clinical management of structural glaucoma progression.