Choroidal thickness measured with swept source optical coherence tomography in posterior staphyloma strongly correlates with axial length and visual acuity

K. V. Chalam,Kumar Sambhav

doi:10.1186/s40942-019-0166-y

Abstract

PurposeTo measure the choroidal thickness in patients with high myopia from staphyloma using swept source OCT (SS-OCT) in Early Treatment Diabetic Retinopathy Study (ETDRS) fields and compare to normal cohort. The study also evaluated the correlation between choroidal thickness with axial length and best-corrected visual acuity (BCVA).MethodsIn this prospective cross sectional study, 37 eyes of 20 patients with high myopia from staphyloma and 86 eyes of 43 normal subjects were included. In each eye, horizontal scans centered on the fovea (12 × 9 mm) were performed using SS-OCT (DRI-OCT, Topcon, Japan). Choroidal thickness in 9 ETDRS subfields, including central subfield (CSF) was analyzed and correlated with axial length as well as BCVA.ResultsThe axial length and BCVA in the high myopia from staphyloma group ranged from 25.12 to 33.54 mm (28.4 ± 1.2) and 20/20–20/400, respectively. The choroidal thickness in staphyloma group was 85.53 ± 48.61 μm as compared to 250.24 ± 71.01 μm in the normal group (p < 0.0001). Stepwise regression analysis showed that axial length strongly correlated with decreased choroidal thickness (p < 0.001) in staphyloma group (r = 0.71, r2 = 0.5). Refractive error and BCVA moderately correlated(r = − 0.47; r2 = 0.22) with choroidal thickness (p < 0.001).ConclusionChoroidal thickness in staphyloma (measured with novel technology of SS-OCT) patients is markedly reduced compared to normal controls. In addition, choroidal thickness strongly correlated with axial length of the eye and inversely correlated with visual acuity. This testing modality maybe used as a good predictor of visual acuity in patients with high myopia from staphyloma.

Highlights

Posterior staphyloma, an abnormal protrusion of the uveal tissue due to weakness of outer layer of eye typically involves macula, causes increase in axial length of eye and thereby high myopia
There were 23 women and 20 men included in the normal subject group and 11 women and 9 men in staphyloma group
Three eyes in staphyloma group were excluded from analysis (1 patient was mono-ocular and in 2 eyes scan quality did not meet the inclusion criteria)

Summary

Introduction

An abnormal protrusion of the uveal tissue due to weakness of outer layer of eye (sclera) typically involves macula, causes increase in axial length of eye and thereby high myopia. The distance between the Bruch’s membrane and the sclera is markedly decreased and thinning of the choroid is noted (30 μm vs 250 μm in normals) with axial elongation of globe in myopic patients [2, 3]. This thinning of choroid is associated with loss of choriocapillaris and retinal pigment epithelium. Accurate measurement of choroidal thickness is difficult with spectral domain OCT (SDOCT) or enhanced depth imaging (EDI) due to limited penetration and poor delineation of the deeper posterior border of the choroid. Choroidal thickness measurements between manual segmentation by Spectralis SD-OCT and automated segmentation by SS-OCT (DRI OCT-1) may differ by ~ 50 μm (the measurements by SD-OCT being higher) [4]

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Results

Conclusion