Korean J Ophthalmol.  2018 Feb;32(1):38-44. 10.3341/kjo.2017.0031.

Factors Affecting ISNT Rule Satisfaction in Normal and Glaucomatous Eyes

Affiliations
  • 1Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea. xcski@hanmail.net
  • 2Department of Ophthalmology, Seoul National University Hospital, Seoul, Korea.
  • 3Department of Ophthalmology, SMG-SNU Boramae Medical Center, Seoul, Korea.

Abstract

PURPOSE
To determine the factors that influence the satisfaction of the "˜ISNT rule' (neural rim width: inferior ≥ superior ≥ nasal ≥ temporal) in normal and glaucomatous eyes.
METHODS
The medical records of patients that visited Boramae Medical Center, Seoul, Korea, were reviewed. Each group of normal and glaucomatous eyes was divided into subgroups based on whether or not they satisfied the ISNT rule. ISNT rule assessment was performed by measuring the rim width with stereoscopic optic disc photographs using ImageJ software. Logistic regression analysis was performed to determine the factors that affect ISNT rule satisfaction.
RESULTS
Seventy-seven normal eyes and 97 glaucomatous eyes were included in the study. The ISNT rule was intact in 59 (76.6%) of the normal eyes and was violated in 71 (73.2%) of the glaucomatous eyes. Logistic regression analysis revealed a significant influence of axial length in violation of the ISNT rule in the normal eye group, while the mean deviation value was a significant factor for violation of the ISNT rule in the glaucomatous eye group.
CONCLUSIONS
The ISNT rule should be cautiously applied when evaluating normal eyes with long axial lengths. In addition, the ISNT rule might not be as effective for detecting early glaucoma.

Keyword

Axial length; Glaucoma; Nerve fibers; Optic disk; Optic nerve diseases

MeSH Terms

Glaucoma
Humans
Korea
Logistic Models
Medical Records
Nerve Fibers
Optic Disk
Optic Nerve Diseases
Seoul

Figure

  • Fig. 1 Clinical assessment of the normal optic disc. Optic disc center was defined as the intersection of the longest diameter (LD) and shortest diameter (SD) of the optic disc. Superior (S) and inferior (I) rims were defined as the vertical line that passes through the optic disc center. Nasal (N) and temporal (T) rims were defined as the horizontal line that passes through the optic disc center.


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