The potential of spectral domain optical coherence tomography imaging based retinal biomarkers

Abstract

Background: Biomarker", a merged word of "biological marker", refers to a broad subcategory of medical signs that objectively indicate the state of health, and well-being of an individual. Biomarkers hold great promise for personalized medicine as information gained from diagnostic or progression markers can be used to tailor treatment to the individual for highly effective intervention in the disease process. Optical coherence tomography (OCT) has proved useful in identifying various biomarkers in ocular and systemic diseases.

Main body: Spectral domain optical coherence tomography imaging-based biomarkers provide a valuable tool for detecting the earlier stages of the disease, tracking progression, and monitoring treatment response. The aim of this review article is to analyze various OCT based imaging biomarkers and their potential to be considered as surrogate endpoints for diabetic retinopathy, age related macular degeneration, retinitis pigmentosa and vitreomacular interface disorder. These OCT based surrogate markers have been classified as retinal structural alterations (macular central subfield thickness and cube average thickness); retinal ultrastructural alterations (disruption of external limiting membrane and ellipsoid zone, thinning of retinal nerve fiber layer and ganglion cell layer); intraretinal microangiopathic changes; choroidal surrogate endpoints; and vitreoretinal interface endpoints.

Conclusion: OCT technology is changing very quickly and throughout this review there are some of the multiple possibilities that OCT based imaging biomarkers will be more useful in the near future for diagnosis, prognosticating disease progression and as endpoint in clinical trials.

Keywords: Age related macular degeneration; Biomarkers; Diabetic retinopathy; Inherited macular disorder; Optical coherence tomography; Retinitis pigmentosa; Vitreomacular interface disorders.

Fig. 1

Spectral domain optical coherence tomography showing grades of disruption of the ELM and EZ. a Grade 0: no disruption of ELM and EZ. b Grade 1: ELM disruption (white arrowhead), EZ intact. c Grade 2: both ELM and EZ disrupted (yellow arrow)

Fig. 2

Retinal Nerve Fiber Layer (RNFL) thickness analysis using optic disc cube 200 × 200 feature depicting on RNFL thickness deviation map a left eye of patient with non-proliferative diabetic retinopathy showing RNFL thinning, b left eye of patient with proliferative diabetic retinopathy showing thinning of RNFL

Fig. 3

Ganglion Cell Analysis in a patient of diabetes showing thinning in thickness of GCL in GCL thickness map (a), deviation map (b), GCL sectoral quantative analysis (c). d Cross-sectional retinal imaging of GCL (layer)

Fig. 4

Three dimensional visualization shows flecks at the level of retinal pigment epithelium (enclosed in black circle)

Fig. 5

Three dimensional imaging along the X plane showing vitreo-retinal interaction with elevation of inner retinal layers at sites of persistent attachment of vitreous