Reproducibility of Minimum Rim Width and Retinal Nerve Fiber Layer Thickness Measurements using the Anatomic Positioning System in Patients with Glaucoma and Normal Controls

Abstract

Purpose : To perform a prospective, cross-sectional study to determine the test-retest repeatability of minimum rim width (MRW) and retinal nerve fiber layer (RNFL) thickness measurements obtained by spectral-domain optical coherence tomography (SD-OCT) using the anatomic positioning system (APS) protocol in glaucoma patients and controls. In addition, the diagnostic ability of the MRW and RNFL thickness was assessed in three circular peripapillary locations.

Methods : SD-OCT (Spectralis, Heidelberg Engineering GmbH, Heidelberg, Germany) scans of the optic nerve head were obtained twice at one visit using the APS protocol. MRW was measured and RNFL thickness measurements were obtained at three peripapillary locations (3.5 mm, 4.1 mm, and 4.7 mm). Intraclass correlation coefficients (ICCs) and areas under the receiver operating characteristic curve (AUCs) were calculated.

Results : A total of 36 glaucomatous eyes and 59 control eyes were included in the analysis. ICCs of MRW and RNFL thickness (3.5 mm and 4.1 mm circles) ranged between 0.98-1.00 for global measurements. The ICCs of global RNFL thickness measurements in the larger diameter circle (4.7 mm) were lower (0.76 - 0.90). The MRW had an AUC of 0.97 while the RNFL thickness measurements were 0.95, 0.95, and 0.96 for the 3.5 mm circle, 4.1 mm circle, and 4.7 mm circle respectively.

Conclusions : MRW and RNFL thickness measurements using the APS protocol had overall excellent reproducibility and diagnostic performance. Therefore, using this protocol and the novel parameter MRW may be useful in diagnosing and evaluating patients with glaucoma.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Top left: Infrared image of optic nerve head (ONH) with Fovea-to-Bruch’s Membrane Opening (FoBMOC) axis as defined by Anatomic Positioning System (APS). Top right: Infrared image of ONH with 48 Bruch’s membrane opening (BMO) points (dots). Middle: B-scan showing the BMO (red dots), Internal limiting membrane (ILM) (red line), and minimum rim width (MRW) (arrow). Bottom: Sector map showing average BMO-MRW measurements by sector and globally. A diagram of the thickness profile of BMO-MRW (black line).

 

Age-adjusted receiver operating characteristic (ROC) curves for the global Minimum Rim Width (MRW), inner circle (3.5mm) Retinal Nerve Fiber Layer (RNFL) thickness, middle circle (4.1mm) RNFL thickness, and outer circle (4.7mm) RNFL thickness.