Abstract
Purpose: :
To examine choroidal thickness in patients with diabetes using spectral-domain optical coherence tomography (SD-OCT).
Methods: :
Forty-nine eyes of 49 patients with diabetes and 24 eyes of 24 age - matched normal subjects underwent high-definition raster scanning using SD-OCT with frame enhancement software. The patients with diabetes were classified into three groups: 11 patients (11 eyes) with non-proliferative diabetic retinopathy (NPDR) and no macular edema (NPDR group), 18 patients (18 eyes) with NPDR and diabetic macular edema (DME) (DME group) and 20 patients (20 eyes) with treated proliferative diabetic retinopathy (PDR) (PDR group). Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500 micron intervals up to 2500 micrometers temporal and nasal to the fovea. All measurements were performed by 2 independent observers. The correlation between central foveal thickness of the retina and central foveal choroidal thickness was also examined.
Results: :
Reliable measurements of choroidal thickness were obtainable in 75.3% of eyes examined. Mean choroidal thickness showed a pattern of thinnest choroid nasally, thickening in the subfoveal region, and then thinning again temporally. There was a statically significant difference between choroidal thickness of normal subjects and patients in the DME group (P< 0.001) and PDR group (P< 0.001). Mean subfoveal choroidal thickness was thinner in patients with diabetic macular edema (63.3 microns, 27.2% - P < 0.05) or PDR (69.6 microns, 30.0% - P < 0.01), compared with normal subjects. A weak negative correlation between central foveal thickness of the retina and central foveal choroidal thickness was observed in DME group.
Conclusions: :
Choroidal thickness can be measured using SD-OCT high-definition raster scans in the majority of diabetic eyes. Diabetic choroidal thickness is altered in diabetes and related to the degree of severity of retinopathy. The presence of macular edema is associated with a significant decrease in the choroidal thickness.
Keywords: choroid • diabetic retinopathy • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)