Diabetic Macular Edema (DME)

Diabetic Macular Edema (DME)
SYMPTOMS Decrease in central vision, Metamorphopsia
SIGNS Loss of a foveal reflex, Exudates in the shape of a circinate ring with retinal thickening found in the middle of the exudative ring, Cystic spaces that start in the outer plexiform layer/Henle’s layer with eventual involvement of the inner nuclear layer, Signs of diabetic retinopathy
If edema is diffuse, there tends to be a greater amount of retinal thickening compared to exudates
If edema is focal, there tends to be a greater amount of exudates compared to retinal thickening
Chronic diabetic macular edema will eventually cause Photoreceptor loss, Macular ischemia, Macular holes, and Sensory retinal detachments at the fovea
WORK-UP Full eye exam with dilated retinal exam, OCT analysis of the macula (signs of diabetic macular edema are best seen with an OCT), OCT-Angiography, Fluorescein Angiography, Fundus Autofluorescence, Fundus photos, Infrared retinal imaging, Watzke-Allen test, Macular photostress test, Amsler grid
TREATMENT Give take home Amsler grid in order to monitor for change
Patient needs to follow up with their primary care provider and control blood sugar, blood pressure, and cholesterol
Criteria for monitoring DME: Best corrected vision in the eye with diabetic macular edema is better than or equal to 20/25, Patient has good glycemic control (HbA1c should be less than or equal to 7%), Diabetic macular edema that is non-center involving, Edema that does not meet the criteria for clinically significant macular edema, and The presence of minimal to moderate non-proliferative diabetic retinopathy
The is no significant difference in visual acuity outcome in the eye with diabetic macular edema when seeing 20/25 or better over a 2 year period when comparing patients who had intravitreal anti-VEGF injections, laser, or were only monitored
Criteria for referring patient to a retinal specialist within 1-2 weeks: Best corrected vision in the eye with diabetic macular edema is worse than or equal to 20/30, Patient has poor glycemic control (HbA1c is worse than 7%), Diabetic macular edema that is center involving, Edema that does meet the criteria for clinically significant macular edema, or The presence of diabetic retinopathy that is worse than moderate non-proliferative diabetic retinopathy
Treatment for diabetic macular edema includes intravitreal anti-VEGF injections, focal laser, grid laser, intravitreal steroid injections, intravitreal steroid implants, and a vitrectomy with ILM strip
FOLLOW-UP If monitoring diabetic macular edema, the patient should be seen back in 2-3 months
If macula is stable following treatment by retinal specialist, patient should be seen back in 4-6 months (Also depends on severity of diabetic retinopathy as well)
ADDITIONAL LAB | TESTS The patient needs to follow-up with their PCP for additional testing if not already done which includes the following: Blood pressure, Fasting blood sugar, HbA1c, Lipid panel, CBC with differential, Renal function testing
ETIOLOGY Occurs due to breakdown of the inner blood-retina barrier which leads to leakage of plasma and exudates from the retinal capillaries specifically in the deep vascular complex
DIFFERENTIAL DX Central serous chorioretinopathy, Cystoid macular edema
NOTES Diabetic macular edema is the most common reason for decrease in vision in patients with diabetic retinopathy
Diabetic macular edema can happen during any stage of diabetic retinopathy but it is more likely to occur in the later stages
Exudates in the foveal region can become visually devastating especially if longstanding
Cystic spaces in the fovea region tend to be larger than the rest of the macula as there are fewer and weaker Muller cells in this area
Classification based on fundus evaluation (Clinically Significant Macular Edema)
Retinal thickening at or within 500 microns of the fovea
Exudates at or within 500 microns of the fovea with associated retinal thickening (Why not just exudates? There can be exudates present without any active edema as fluid is typically absorbed sooner than exudates)
Retinal thickening greater than 1DD in size within 1 DD of the fovea
Classification based on OCT evaluation
Center-Involving Diabetic Macular Edema: Retinal thickening at the macula that involves the central subfield zone that is 1mm in diameter
Non-Center Involving Diabetic Macular Edema: Retinal thickening at the macula that does not involve the central subfield zone that is 1mm in diameter
Signs associated with a higher risk of poor vision and poor prognosis: Disorganization of retinal inner layers (DRIL) that includes disruption of the ganglion cells, IPL, INL, OPL, and ONL / ELM and ellipsoid zone disruption / or Presence of VMT and ERMs
Diabetic Macular Edema (DME): OCT of the macula demonstrating center-involving diabetic macula edema with associated cystic spaces, exudates, and a foveolar sensory retinal detachment https://medicine.uiowa.edu/eye/patient-care/imaging-services/optical-coherence-tomography

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