Abstract
Purpose:
Transverse section analysis (TSA) of optical coherence tomography (OCT) scans offers the opportunity to image the distribution of intraretinal cysts or subretinal fluid in a single en face image. Pooling is a phenomenon caused by dye accumulation in retinal cysts during a late phase fluorescence angiography. The aim of this study was to reveal if FA can be replaced by TSA scans in imaging retinal cysts in diabetic macular edema.
Methods:
In 25 eyes of 25 patients with clinically significant diabetic macular edema a FA examination and OCT TSA scan at minute 5 were performed simultaneously using Spectralis HRA and OCT (Heidelberg engineering). Transverse section full retina analysis and FA images were then superimposed and correlated regarding (1) the location and (2) the planimetric dimension of intraretinal cyst formation in OCT and the area of pooling or hyperfluorescence in FA (MATLAB 2012a, The MathWorks). Furthermore, for each area of intraretinal fluid accumulation in OCT the source of leakage was analysed in both imaging techniques.
Results:
There was no significant correlation between the location of intraretinal cysts in TSA images and visible pooling in FA images at minute 5. Further, there was no correlation between the planimetric dimension of intra-retinal cyst areas and detectable local pooling or hyperfluorescence areas in FA. The source of leakage was defined in FA images by detecting microaneurysms, capillary non-perfusion or capillary leakage depending on the individual edema type graded by the SAVE grading system. These changes in FA were not detectable in TSA images.
Conclusions:
OCT transverse section analysis and FA offer complementary information and are not interchangeable in imaging intra-retinal cyst formation. TSA reveals the amount and location of intraretinal fluid accumulation in more detail than pooling or changes in fluorescence in FA. FA in contrast to TSA is capable to detect the individual source of leakage and cyst formation. Hence, it remains to be clarified if a combination of TSA and OCT angiography together can replace FA in certain cases of clinically significant diabetic macular edema.