Purpose:
To date the vascular theory in the pathophysiology of glaucoma is still being controversially discussed. The blood supply to the prelaminar portion of the optic nerve comes mostly from the choroid. Recent studies showed a differing choroidal thickness with age and in patients with central serous chorioretinopathy with a potentially varying frequency of glaucoma. The aim of this study was to assess the choroidal thickness as a measure of the blood flow to the optic nerve in patients with primary open angle glaucoma.
Methods:
Enhanced depth imaging OCT images were obtained in patients with established diagnosis of primary open angle glaucoma (Group 1) and an age-matched healthy control group (Group 2) using Heidelberg SpectralisTM SD-OCT. Retrospective analysis and comparison of the choroidal thickness, measured from the outer border of the retinal pigment epithelium to the inner border of the sclera at foveal horizontal sections, was performed. Additional parameters assessed were age, gender, overall mean RNFL thickness, best corrected visual acuity, refraction, lens status and cup-to-disk ratio. Furthermore, disease duration and glaucomatous therapy was documented. Patients with high myopia or hyperopia, any retinal or retinal pigment epithelial pathology and poor image quality were excluded.
Results:
A total of 62 eyes with 21 eyes (11 right) in Group 1 and 41 eyes (20 right) in Group 2 were examined. Demographic characteristics were comparable among the groups. The refractive error was ±5.5dpt spherical and ±1.5dpt cylindrical in Group 1 and ±5.0dpt spherical and ±3.00dpt cylindrical in Group 2. Central retinal thickness showed a median of 233.6µm (Interquartile-Range IQR [192;315] in Group 1 and 231µm [178;327] in Group 2, respectively (p=0.907). Choroidal thickness was statistically significant lower in Group 1 (median 247µm, IQR 90;380) than in Group 2 (median 269µm, IQR 137;528, p=0.030).
Conclusions:
Choroidal thickness seems to be lower in glaucoma patients compared to healthy controls. These findings could possibly support the theory of reduced blood flow from the choroid being one of the contributing factors in patients with glaucoma.
Keywords: choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)