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Rachel Sarah Varughese, Rebecca Rewbury, Andrew Want, Victor Chong; Foveal choroidal thickness in patients with diabetic retinopathy and diabetic macular edema. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4431.
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Diabetic retinopathy (DR) is a leading cause of visual loss in the working age population yet its pathogenesis remains incompletely understood. It is postulated that the choroidal layer may play a role but it is unknown whether the choroidopathy is associated with DR or diabetic macular edema (DME). The recent development of spectral domain optical coherent topography (SD-OCT) with enhanced depth imaging (EDI) has enabled adequate visualisation of the choroidal layer and subsequent measurement of its thickness. The relationship between choroidal thickness, DME and progression of DR is, however, unclear as the few existing studies report conflicting results. We hypothesised that choroidal thickness would correlate more closely with DR rather than DME as it is more likely to represent a diffuse pathological process. The present study therefore aimed to investigate whether there is a relationship between subfoveal choroidal thickness and (1) the severity of DR and (2) the presence of DMO.
This study was approved by the local Ethics Committee. A complete list of all patients who had attended the diabetic eye clinic at Oxford Eye Hospital between January 2012 and February 2013 was collected. We have included only type II diabetics, with a documented history of foveal involving DME in at least one eye, no prior treatment, and without any other retinal pathologies. Two masked observers analysed 145 eyes. The severity of DR was assessed on Optomap retinal photography. Corresponding Heidelberg Spectralis EDI-OCT images were used to determine the presence of foveal involving DME and to measure sub-foveal choroidal thickness.
1) In proliferative DR, there was a statistically significant increase in choroidal thickness (242.1microns) when compared to the mild non-proliferative DR group (217.7microns), p=0.027. 2) DME was associated with a non-statistically significant increase in choroidal thickness (225.4microns) compared to eyes without DMO (209.3microns), p=0.13. This may reflect the higher incidence of more severe retinopathy in the eyes with DME.
The results suggest that there is an association between choroidal thickness and the progression of DR rather than DME. It is possible that the choroid responds to the retinal vascular disease. EDI-OCT is an effective non-invasive method of imaging the choroid, which may prove useful in the clinical assessment of diabetic eye disease.
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