Detection of Glaucoma Deterioration in the Macular Region with Optical Coherence Tomography: Challenges and Solutions

Abstract

Purpose: Macular imaging with optical coherence tomography (OCT) measures the most critical retinal ganglion cells (RGCs) in the human eye. The goal of this perspective is to review the challenges to detection of glaucoma progression with macular OCT imaging and propose ways to enhance its performance.

Design: Perspective with review of relevant literature.

Methods: Review of challenges and issues related to detection of change on macular OCT images in glaucoma eyes. The primary outcome measures were confounding factors affecting the detection of change on macular OCT images.

Results: The main challenges to detection of structural progression in the macula consist of the magnitude of and the variable amount of test-retest variability among patients, the confounding effect of aging, lack of a reliable and easy-to-measure functional outcome or external standard, the confounding effects of concurrent macular conditions including myopia, and the measurement floor of macular structural outcomes. Potential solutions to these challenges include controlling head tilt or torsion during imaging, estimating within-eye variability for individual patients, improved data visualization, the use of artificial intelligence methods, and the implementation of statistical approaches suitable for multidimensional longitudinal data.

Conclusions: Macular OCT imaging is a crucial structural imaging modality for assessing central RGCs. Addressing the current shortcomings in acquisition and analysis of macular volume scans can enhance its utility for measuring the health of central RGCs and therefore assist clinicians with timely institution of appropriate treatment.

Figure 1.

An example of clustering of the superpixels from the macular volume scans of the Spectralis OCT based on age-related rates of change in normal subjects. The Posterior Pole Algorithm of the Spectralis OCT provides an 8×8 array of 3°×3° superpixels within the central 24° of the macula. In this example, the superpixels demonstrating similar age-related rates of change in the ganglion cell layer were clustered in a pericentral pattern with thicker superpixels displaying larger absolute age-related rates of change. This particular set of clusters was derived from hierarchical clustering using 5- and 10-year age brackets and k-means clustering using 10-year age brackets. Data from the foveal pit were excluded from analysis (black circle) since there is no retinal ganglion cells in this area. (Reprinted from Tong J, Phu J, Khuu SK, et al. Development of a Spatial Model of Age-Related Change in the Macular Ganglion Cell Layer to Predict Function From Structural Changes. Am J Ophthalmol. 2019, with permission from Elsevier.)

Figure 2.

Sectoral absolute mean age-related rate change of the macular retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), and outer nuclear layer (ONL) thickness (right eye format). The innermost circle has a diameter of 1 mm with an incremental increase of 1 mm in the diameter of each concentric circle (key, upper right). Each circle, except the most central one, is divided into twelve 30° sectors. The darker red colors denote more negative rates and darker green sectors show more positive rates (key, bottom right). I: inferior; N: nasal; S: superior; T: temporal. The rates were calculated based on a cross-sectional group of 246 White subjects. (Reprinted from Chauhan BC, Vianna JR, Sharpe GP, et al. Differential Effects of Aging in the Macular Retinal Layers, Neuroretinal Rim, and Peripapillary Retinal Nerve Fiber Layer. Ophthalmology. 2019, with permission from Elsevier.)

Figure 3.

Sectoral relative mean age-related rate change of the macular retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), and outer nuclear layer (ONL) thickness expressed in percent loss (right eye format). The innermost circle has a diameter of 1 mm with an incremental increase of 1 mm in the diameter of each concentric circle (key, upper right). Each circle, except the most central one, is divided into twelve 30° sectors. The darker red colors denote more negative rates and darker green sectors show more positive rates (key, bottom right). I: inferior; N: nasal; S: superior; T: temporal. The rates were calculated based on a cross-sectional group of 246 White subjects. (Reprinted from Chauhan BC, Vianna JR, Sharpe GP, et al. Differential Effects of Aging in the Macular Retinal Layers, Neuroretinal Rim, and Peripapillary Retinal Nerve Fiber Layer. Ophthalmology. 2019, with permission from Elsevier.)