Agreement Between Cirrus HD-OCT Circumpapillary Retinal Nerve Fiber layer Thickness (RNFLT) Analysis and a Novel Computation Algorithm for Analysis of the RNFLT Over a 6 × 6 mm2 Peripapillary Area

Abstract

 

Purpose:

 

To evaluate the agreement between Cirrus HD-OCT circumpapillary retinal nerve fiber layer thickness (RNFLT) analysis and a novel computation algorithm for analysis of the RNFLT over a 6 × 6 mm² peripapillary area.

 

Methods:

 

One Cirrus HD-OCT optic nerve scan was obtained weekly from healthy participants and glaucoma patients for four consecutive weeks. The RNFLT map displays the pattern of peripapillary RNFLT using a color-coded scale, ranging from black (0 µm) to white (350 µm). RGB pixel values of the map were automatically obtained using ImageJ (ver. 1.44P, NIH, Bethesda, MD). Custom Perl scripts matched RGB pixel values with the RGB of the color-coded scale and assigned the RNFLT value in order to obtain average and quadrant RNFLT over the 6 × 6 mm² peripapillary area. Agreement between peripapillary area RNFLT map and circumpapillary RNFLT analysis was calculated using the limits of agreement (LoA), and the coefficient of determination (R²) was calculated.

 

Results:

 

27 eyes from 19 glaucoma patients and 22 eyes from 13 healthy individuals were included. 95% LoA and R² between the two RNFLT analysis methods for average and quadrant RNFLT in the two groups are shown in Table 1. RNFLT analysis was strongly correlated in both groups except moderately correlated in the nasal quadrant. Agreement was good in both groups with closer agreement in temporal and nasal quadrants than superior and inferior quadrants. Mean circumpapillary RNFLT analysis was consistently higher than mean peripapillary RNFLT Map analysis.

 

Conclusions:

 

Further study should be done to evaluate the diagnostic performance of the Cirrus HD-OCT peripapillary RNFLT Maps and their ability to monitor glaucomatous RNFLT progression.  

 

Keywords: imaging/image analysis: clinical • optic disc