Purpose
To measure and compare choroidal thickness (CHT) in diabetic and glaucoma patients with good visual acuity versus controls imaged with Spectral Domain (SD) Optical Coherence Tomography (OCT) using the enhanced depth imaging (EDI) technique.
Methods
A retrospective chart review was performed, and patients with glaucoma, diabetes and non macular diagnoses were identified. From the 11 months of Jan 2012 to Dec 2012, 164 patients had EDI OCT performed with the Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany) device. Choroidal thickness (CHT) was measured using the calipers provided by the software of the Heidelberg Spectralis unit: at the fovea, calipers were placed at the outer part of the hyperreflective line corresponding to the base of the Retinal Pigment Epithelium (RPE) and to the sclerochoroidal junction. OD and OS CHT were averaged for each patient. Study inclusion criteria: Snellen Va =20/20-20/40, glaucoma diagnosis (GL), background diabetic retinopathy (DM), Controls (CON) were defined as having no macular pathology, such as posterior vitreous detachment, refractive error, headaches. Exclusion criteria: previous retinal laser, vitreo-retinal surgery, anti-VEGF therapy. Student t test, Pearson Correlation, Kruskal Wallis and Wilcoxon rank-sum tests were used for statistical analysis.
Results
Age-matched: 24 eyes each from GL, DM and CON groups with good visual acuity (20/20-20/40) . There was no significant difference between gender (Pearson's chi sq), age (Kruskal-Wallis equality-of-populations rank test) among the groups. Median CHT for GL and DM compared to CON were 174.5, 181.0, and 236.8 (μm), respectively. There was a significant difference in choroidal thickness between GL vs. CON(p = 0.003) and DM vs. CON (p = 0.03), but no significant difference between GL vs. DM (Kruskal-Wallis and Wilcoxon rank-sum tests). Similar results were found with parametric tests (see table 2).
Conclusions
Ocular blood flow abnormalities is implicated in the pathogenesis of glaucoma and diabetic retinopathy. The choroid supplies 85% of ocular blood flow. The thinner choroidal thickness measurements suggest a decrease of choroidal blood flow in patients with glaucoma and early diabetic retinopathy despite good visual acuity.
Keywords: 436 blood supply •
550 imaging/image analysis: clinical •
461 clinical (human) or epidemiologic studies: natural history