Contents
Retinal thickening caused by the accumulation of intraretinal fluid, primarily in the inner and outer plexiform layers as a result of hyperpermeability of the retinal vasculature.
- M/C cause of vision loss among diabetics
Clinically-significant macular edema (CSME):
Early Treatment of Diabetic Retinopathy Study (ETDRS) definition, consisting of any of the following
- Retinal thickening at or within 500 µ or 1/3 the disc diameter of the fovea.
- Hard exudates at or within 500 µ of the fovea, with adjacent retinal thickening.
- Retinal thickening greater than one disc diameter (1500 µ) in size that is within one disc diameter from the fovea.
Aetiology
Systemic risk factors:
- Age, male gender
- Systolic blood pressure
- Hyperlipidemia
- Proteinuria
- Insulin use
- Diuretic use
- Duration of diabetes
- Higher glycosylated hemoglobin
- Pan-retinal photocoagulation (PRP)
Local factors:
Angiogenic factors
- Vascular endothelial growth factor (VEGF)
- Protein kinase C (PKC)
- Prostaglandins
- Growth hormone
- Anatomy of the posterior hyaloid face
Clinical features
DME present with a range of visual symptoms depending on the degree to which the fovea is involved and the chronicity of the edema.
- Metamorphopsia
- Fluctuation of vision from day-to-day or even over the course of a day
Diagnosis
DME is diagnosed stereoscopically.
Fundus examination:
Fluorescein angiography (FA)
Optical coherence tomography (OCT):
Diagnostic test of choice
Differential diagnosis:
- Hypertension
- Retinal vein occlusion (RVO)
- Ruptured microaneurysm
- Radiation
- Irvine-Gass syndrome
- Subfoveal choroidal neovascularisation
Management
Laser photocoagulation:
Mainstay treatment for clinically-significant macular edema (CSME)
- Focal laser photocoagulation
- Scatter laser photocoagulation
Anti–VEGF agents:
- Ranibizumab
- Bevacizumab
- Aflibercept “VEGF trap”
Intravitreal corticosteroids:
Benefits of glucocorticoids depend on their anti-inflammatory and anti-VEGF effects
- Triamcinolone acetonide (TA)
Pars plana vitrectomy (PPV):
Removes traction forces and proinflammatory substances and increases the oxygenation of inner retinal layers; indicated in refractory cases
