Applicability of ISNT Rule Using Bruch's Membrane Opening-based Optic Nerve Head Parameters

ABSTRACT

Purpose@#To evaluate the applicability of the ISNT rule (neuroretinal rim thickness order inferior > superior > nasal > temporal)when using Bruch's membrane opening-based optic nerve head parameters to discriminate between normal and glaucomatouseyes. @*Methods@#The medical records of 41 normal eyes and 62 open-angle glaucoma eyes were reviewed retrospectively. We analyzedthe neuroretinal rim thickness values corresponding to the superior, inferior, nasal, and temporal sides of the optic disc asmeasured using color stereo optic-disc photographs, Bruch’s membrane opening-minimum rim width (BMO-MRW), theBMO-MRW average, and Bruch’s membrane opening-minimum rim area (BMO-MRA). The sensitivity and specificity of the ISNTrule in differentiating normal and glaucomatous eyes were compared across the four methods. @*Results@#In normal and glaucomatous eyes, measuring neuroretinal rim thickness in color stereo optic-disc photographs producedlarger values for the superior, inferior, nasal, and temporal sides compared to measurements using BMO-MRW and theBMO-MRW average (p< 0.001). With respect to ISNT rule compliance using the four methods, the sensitivities of theBMO-MRW average and BMO-MRA methods were significantly higher than that when disc photographs were used (82.3% vs.98.4%, p< 0.05; and 82.3% vs. 95.2%, p< 0.05, respectively). Specificity did not differ significantly among the four methods. @*Conclusion@#BMO-based optic nerve head parameters exhibited higher diagnostic power for differentiating between normal andglaucomatous eyes based on the ISNT rule, compared with the classic method of using disc photographs.