J Korean Ophthalmol Soc.  2020 Aug;61(8):921-928. 10.3341/jkos.2020.61.8.921.

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

  • 1Department of Ophthalmology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea


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.
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.
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.
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.


Bruch’s membrane opening-minimum rim area; Diagnostic ability; ISNT rule; Glaucoma optic disc
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