Choroidal Biomarkers: A Repeatability and Topographical Comparison of Choroidal Thickness and Choroidal Vascularity Index in Healthy Eyes.

Katharina Breher,Louise Terry,Siegfried Wahl,Thomas Bower

doi:10.1167/tvst.9.11.8

Katharina Breher, Louise Terry + Show 2 more

Open Access

https://doi.org/10.1167/tvst.9.11.8

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Abstract

PurposeChoroidal thickness (ChT) and choroidal vascularity index (CVI) represent two important metrics in health-, disease-, and myopia-related studies. Wide-field swept-source optical coherence tomography (OCT) provides improved and extended imaging and extraction of choroidal variables. This study characterizes the topography and repeatability of these parameters in healthy eyes.MethodsSwept-source OCT volume scans were obtained on 14 young adult patients on three separate days. ChT and CVI were automatically corrected for image magnification and extracted for different enface regions within an extended ETDRS grid of 10 mm diameter. Topographical distribution, correlation to ocular length, and intersession repeatability of both choroidal parameters were assessed.ResultsCVI showed little fluctuation between subfields, unlike ChT, which demonstrated thinning toward the peripheral choroid (coefficients of variation 5.92 vs. 0.89). ChT showed a consistent negative correlation with axial length (ρ = −0.05 to −0.61), although this was only statistically significant in the inner superior subfield (P = 0.02). There was no consistent or significant relationship between CVI and axial length or between CVI and ChT. The repeatability of CVI measurements (3.90%–5.51%) was more consistent between scan regions than ChT measurements (10.37–20.33 µm).ConclusionsCVI values were consistent across the central 10 mm of the retina, while ChT reduced with eccentricity. The repeatability of both parameters is similar to the effect size reported in many studies using the choroid as a biomarker, which should be considered in the interpretation of findings.Translational RelevanceThis study provided normative as well as metrological information for the clinical interpretation of ChT and CVI in health and disease.

Highlights

The choroid is located between the retina and the sclera and consists of five layers—Bruch’s membrane, choriocapillaris, Haller’s layer, Sattler’s layer, and the suprachoroid—with its main task to provide blood supply to the outer retina.[1,2] The choroid is suggested to play an essential role in various fields of human eye research
choroidal vascularity index (CVI) values were consistent across the central 10 mm of the retina, while choroidal thickness (ChT) reduced with eccentricity
The repeatability of both parameters is similar to the effect size reported in many studies using the choroid as a biomarker, which should be considered in the interpretation of findings

Summary

Introduction

The choroid is located between the retina and the sclera and consists of five layers—Bruch’s membrane, choriocapillaris, Haller’s layer, Sattler’s layer, and the suprachoroid—with its main task to provide blood supply to the outer retina.[1,2] The choroid is suggested to play an essential role in various fields of human eye research. Changes to the choroidal structure have been suggested as biomarkers for a variety of ocular pathologies; altered choroidal thickness (ChT) was previously observed in central serous chorioretinopathy,[3] Vogt-Koyanagi-Harada disease,[4] and polypoidal choroidal vasculopathy and exudative age-related macular degeneration.[5] bidirectional changes of ChT influence the regulation of eye growth due to its location in the signaling pathway from retina to sclera.[2,6].

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