Patterns of glaucomatous progression in the region of the circumpapillary retinal nerve fiber layer associated with the superior hemifield of the 24-2

Abstract

Purpose : While patterns of glaucomatous visual field (VF) progression have been characterized, [1] less is known about the patterns of OCT circumpapillary retinal nerve fiber layer (cRNFL) loss. Here we examine the rate and pattern of local cRNFL loss in a region associated with the superior hemifield of the 24-2 VF.[2]

Methods : 30 eyes of 25 patients with a diagnosis of glaucoma and evidence of progression on OCT had sdOCT disc cube scans (Topcon OCT 3000) on at least 3 separate visits. The time between the first and last visits ranged from 2.5 to 11.4 (mean 7.2±2.6) years. The enface images of disc cube scans from different sessions were aligned using blood vessels (Fig. 1A) to assure that the region of interest (ROI = 0° to -135°) of each coincided. This ROI (red in Fig. 1B) corresponds to the cRNFL associated with the superior hemifield of the 24-2 VF. The region of progression (ROP) was defined based upon the difference in cRNFL thickness between the first and subsequent visit (blue line in Fig. 1C, bottom). The locations of its leading (close to fixation) and trailing edges (blue arrows), as well as the depth of its deepest location (green arrow) were determined. Average and total loss in the ROP were also measured (hatched region, Fig. 1).

Results : On average, the ROP between the first and last visit was 89° wide, 66% of the width of the ROI, and it ranged from 40° to 134°. The ROP widening occurred both towards and away from fixation in 16 eyes, only away from fixation in 4, only towards in 8, and neither in 2. The rate of widening toward and away from fixation was comparable. The ROP of 27 of the 30 eyes also deepened at the point of maximal loss. Eyes with similar average loss (Fig. 2B), or similar remaining average thickness (Fig. 2A) in the ROI had different patterns.

Conclusions : The cRNFL loss associated with the superior 24-2 VF shows progression over a relatively wide cRNFL region and proceeds toward and away from fixation. As with VFs,[1] the abnormal region widens and deepens over time. However, progression is more complicated, as eyes with similar average cRNFL thicknesses after progression can have very different patterns of remaining cRNFL, and eyes with similar amounts of cRNFL loss during progression can have very different patterns of loss. 1. Boden et al. AJO, 2004; 2. Hood PRER, 2017.

This is a 2020 ARVO Annual Meeting abstract.

 

Figure 1

 

Figure 2