Diabetic Macular Edema

SALIENT FEATURES

Diabetic macular edema (DME), the most common cause of visual loss in patients with diabetic retinopathy (DR), is prevalent in 4.2% to 12.8% of patients with diabetes.¹
DME may appear in patients with nonproliferative diabetic retinopathy (NPDR) or proliferative diabetic retinopathy (PDR).
The pathogenesis of DME is multifactorial and incompletely understood; however, both vascular permeability and inflammation have been implicated in its development.²

OCT IMAGING

Optical coherence tomography (OCT) is considered the gold standard for the diagnosis and monitoring of DME.
The basic morphologic features of DME include intraretinal fluid, which presents on OCT as focal hyporeflective circular structures within the retinal tissue, and subretinal fluid, which presents as a hyporeflective space between the retina the retinal pigment epithelium (RPE) (Figure 7.1).
There are some data to suggest that patients that present with primarily subretinal fluid experience greater visual acuity gain after treatment than those with cystoid macular edema.³

Central foveal thickness (CFT) and mean central subfield thickness (CST) are standardized OCT-derived measurements thickening that may help to identify abnormal thickening and can track changes over time (Figure 7.2C and D).

FIGURE 7.1 Optical coherence tomography (OCT) of a patient with diabetic macular edema highlighting many common features of diabetic retinopathy and diabetic macular edema including hyperreflective dots (green arrow), subretinal fluid (yellow asterisk), intraretinal fluid (green asterisk), vitreomacular adhesion (white arrow), epiretinal membrane (pink asterisk), and microaneurysm (yellow arrow).

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