A Systematic Correlation of Angiography and High-Resolution Optical Coherence Tomography in Diabetic Macular Edema Matthias Bolz, MD, 1 Markus Ritter, MD, 1 Miklos Schneider, MD, 1,2 Christian Simader, MD, 1 Christoph Scholda, MD, 1 Ursula Schmidt-Erfurth, MD 1 Purpose: To correlate leakage patterns in fluorescein angiography (FA) images and retinal morphologic features in high-definition optical coherence tomography (HD OCT) images in diabetic macular edema. Design: Prospective pilot study and case series. Participants: Nine consecutive patients (10 eyes) with diabetic macular edema. Methods: All patients were examined using FA (HRA 2; Heidelberg Engineering) and HD OCT (Carl Zeiss Meditec; resolution, 512128 pixels, 5.85.8 mm, and high-resolution scans consisting of 4096 A scans) on the same day. Using Adobe Photoshop (CS2 Version 9.0; Adobe Systems Incorporated, San Jose, CA) a grid containing 157 fields was superimposed on the HD OCT en face image and a late-phase FA image according to retinal landmarks. In each patient, a standardized analysis of 105 subfields was performed to provide a characterization of the type of vascular leakage in FA and the associated retinal morphologic changes in corresponding locations. Main Outcome Measures: Angiographic leakage type and structural alteration in retinal morphologic features in OCT. Results: There was a high consistency between FA and OCT in the petaloid pattern of hyperfluorescence that correlated with the presence of large cystic spaces in the outer nuclear layer (ONL) and the outer plexiform layer (OPL) with or without subretinal fluid in 30.4% and 69.6% of graded fields, respectively. A honeycomblike pattern of hyperfluorescence was associated with swelling and cystic spaces in ONL, OPL, the inner nuclear, and the inner plexiform layer in 71.4% of graded fields. Diffuse patterns of hyperfluorescence did not correlate with characteristic retinal changes in HD OCT, but rather showed diversity in the type of morphologic alteration. The presence of central fluid pooling, such as subretinal fluid, could be identified only by HD OCT and not by FA. Conclusions: In the examined patients, a petaloid pattern and a honeycomb pattern of hyperfluorescence observed in FA were found to correlate to characteristic changes in HD OCT, whereas a diffuse leakage pattern was associated with nonuniform changes in retinal morphologic features. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2009;116:66 –72 © 2009 by the American Academy of Ophthalmology. Macular edema is known to be one of the main compli- cations in diabetic maculopathy, leading to significant vision loss. The Wisconsin Epidemiologic Study of Di- abetic Retinopathy found a 10-year incidence of diabetic macular edema (DME) to be between 13.9% and 25.4% 1 and several studies reported a poor long-term progno- sis. 2–5 Although DME is found frequently in patients with retinopathy secondary to diabetes mellitus types I and II, its origin and pathophysiologic features are not understood completely. Most importantly, the morpho- logic changes within the different retinal layers corre- sponding to the leakage pattern and exudative activity are poorly identified by clinical examination. Histologic studies of eyes with DME showed that in- traretinal fluid accumulation, such as diffuse edema or cysts, can be found first in the outer plexiform layer (OPL), 6 later spreading throughout all retinal layers. However, these changes were described in a small number of ex vivo examinations without a direct correlation of angiographic and morphologic features. Consequently, several studies have focussed on imaging of retinal in vivo changes secondary to diabetic edema. 7–10 The essential imaging tools for diagnosis and grading of DME and for observing changes over time are fluorescein angiography (FA) and optical coherence tomography (OCT). The first technique, FA, reveals typical retinal vas- cular leakage patterns after systemic dye injection caused by a disturbance of the inner blood–retina barrier. 11 In edema resulting from diabetic microvasculopathy, petaloid, hon- eycomblike, and a diffuse pattern of hyperfluorescence were classified and are usually found in different retinal locations within the edematous macular area. These an- giographic leakage patterns do not provide information about the localization of the extravasate within the dif- ferent retinal layers and the associated damage to the neurosensory structures. The other imaging technique, OCT, gained significant importance throughout the last decade because it allows evaluating retinal morphologic features in detail similar to an in vivo histologic examination. However, conventional 66 © 2009 by the American Academy of Ophthalmology ISSN 0161-6420/09/$–see front matter Published by Elsevier Inc. doi:10.1016/j.ophtha.2008.09.042