Abstract
Purpose: :
To identify optical coherence tomography (OCT) fluid and tissue patterns in patients with diabetic macular edema (DME), that could be predictive of visual outcomes after intravitreal therapy, using minimum intensity projection (MinIP) images from Cirrus™ (Carl Zeiss Meditec, Dublin, CA) spectral domain OCT (SD-OCT).
Methods: :
10 eyes of 8 patients with DME involving the foveal center, and treated with intravitreal triamcinolone (IVT) were studied retrospectively. Patients were imaged with Macular Cube 512x218 scans on separate visits, and pre-IVT and post-IVT images were analyzed and compared to visual acuity (VA). The Cirrus internal limiting membrane and retinal pigmentary epithelium segmentations were used to split the retina into three fractions: an outer half and two quarters referred to as the Inner Quarter and Innermost Quarter. Speckle reduction was performed, and the axial minimum image intensity was determined at each lateral location for each retinal fraction. For comparison, the axially summed intensity was also determined. The resulting en-face images were then segmented using an entropy-based thresholding to give an estimate of the lateral area occupied respectively by fluid and tissue within a 0.75 mm distance from the foveal center.
Results: :
Tissue correlated with decimal VA = 10^(-logMAR): mean tissue area of the three layers before treatment, calculated with MinIP, was correlated with VA after treatment (r = 0.68). More specifically, tissue area in the innermost quarter before IVT was correlated with VA after IVT (r = 0.54). No correlation was found with tissue areas calculated with summed intensity. Pre IVT tissue area was poorly correlated with post IVT retinal volume (r = 0.31).
Conclusions: :
The amount of retinal tissue in the central area may be a prognostic factor for visual acuity after intravitreal injection in eyes with diabetic macular edema. Further studies are needed to confirm those data
Keywords: retina • diabetic retinopathy • macula/fovea