The ISNT Rule: How Often Does It Apply to Disc Photographs and Retinal Nerve Fiber Layer Measurements in the Normal Population?

ABSTRACT:

Purpose

To determine what percentage of normal eyes follow the ISNT rule, and whether ISNT rule variants may be more generalizable to the normal population.

Design

Cross-sectional study.

Methods

Setting: Institutional setting.

Study population

Total of 110 normal subjects.

Observation procedures

Neuroretinal rim assessments from disc photographs and retinal nerve fiber layer (RNFL) thickness measurements from spectral-domain optical coherence tomography.

Main outcome measures

The percentages of subjects that obeyed the ISNT rule and its variants.

Results

The ISNT rule is only valid for 37.0% of disc photograph rim assessments and 43.8% of RNFL measurements. Deviation of the nasal sector from the expected ISNT pattern was a major cause for t

SUBMITTER: Poon LY 

PROVIDER: S-EPMC5705386 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature