Journal d'ophtalmologie clinique et expérimentale
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Optical Coherence Tomography for Diabetic Macular Edema: Early Diagnosis, Classification and Quantitative Assessment

Afef Maalej, Wathek Cheima, Khallouli Asma, Rannen Riadh and Gabsi Salem

Optical Coherence Tomography (OCT) is greatly enhancing our ability to detect macular thickening and is offering new insights on the different morphological patterns of macular edema.
Purpose: To assess the correlation between clinical examination, fluorescein angiography and OCT in the evaluation of Diabetic Macular Edema (DME) We propose a new tomographic classification of DME to better diagnose, catalogue and deal with this complex clinical entity.
Design: This is a prospective double masked study. An informed consent from the patients was obtained.
Methods: This study involved 314 eyes with different stages of diabetic retinopathy, either a clinical DME was present or not. All eyes underwent a clinical exam, fluorescein angiography and OCT scans. The foveal thickness was assessed manually and automatically with the OCT topography software. The correlation between biomicroscopy, angiographic features and OCT data was analyzed, and their association with visual acuity, central foveal thickness and prognosis was evaluated.
Results: The OCT sensitivity in detecting DME was excellent (98.6%). A significant correlation between macular thickness and visual acuity was observed ( r=-0.87). There was a moderate correlation between OCT and clinical assessment of retinal thickness (r= 0.57). The correlation between retinal thickness and angiographic leakage was quite good (r=0.62). OCT revealed five morphologic patterns of DME: type 1: focal macular thickening, type 2: diffuse macular thickening without cysts, type 3: Diffuse cystoid macular edema, type 4: tractional edema (4A: posterior hyaloid traction, 4B: epiretinal membrane, 4C: both posterior hyaloid and epiretinal membrane), type 5: serous retinal detachment.
Conclusion: DME exhibits five different morphologic patterns on OCT having different prognosis values. Correlation between macular morphology and function was obvious. The combined data from both OCT and fluoresein angiography may provide a clearer understanding of the anatomic and physiologic characteristics of DME. The OCT classification is useful for better therapeutic guidelines.