Structural and Functional Evaluations for the Early Detection of Glaucoma

Abstract

The early detection of glaucoma is imperative in order to preserve functional vision. Structural and functional methods are utilized to detect and monitor glaucomatous damage and the vision loss it causes. The relationship between these detection measures is complex and differs between individuals, especially in early glaucoma. Using both measures together is advised in order to ensure the highest probability of glaucoma detection, and new testing methods are continuously developed with the goals of earlier disease detection and improvement of disease monitoring. The purpose of this review is to explore the relationship between structural and functional glaucoma detection and discuss important technological advances for early glaucoma detection.

Keywords: Bruch’s Membrane Opening; Flicker Defined Form Perimetry; Frequency Doubling Perimetry; Ganglion Cell Inner Plexiform Layer; Glaucoma; Lamina Cribrosa; Multifocal Visual Evoked Potential; OCT; OCT Angiography; Pattern Electroretinography; Standard Automated Perimetry.

Figure 1. Structural RNFL Defect Detected with OCT before Functional Defect detected with Humphrey Visual Field 24-2

Significant thinning of the RNFL (denoted with yellow at the first occurrence and red at each subsequently matching occurrence) is seen during the baseline exam and progresses over the course of follow-up. An abnormality is detected using perimetry nearly 4 years later.

Figure 2. OCT Angiography of a Glaucomatous Optic Nerve Head

The vasculature of the optic disc is seen as a projection (nerve head) and three different specific retinal layers (vitreous, radial peripapillary capillaries, choroid).

Figure 3

Ganglion Cell Analysis Detects Damage Missed by Total Macular Thickness Analysis Abnormality detected in the inferior ganglion cell inner plexiform layer (GCIPL) that is reproducible and worsens over time (bottom). Thinning is not detected by analysis of total macular thickness (top).