University of Iowa Health Care

Ophthalmology and Visual Sciences

Diabetic Retinopathy:

From One Medical Student to Another

Jesse Vislisel and Thomas Oetting, MS, MD

Surgery Indications

PRP is advised for patients with vitreous hemorrhage and areas of neovascularization or in patients with large amounts of neovascularization of the optic nerve. It can also be considered in patients with severe NPDR to prevent progression to PDR.

Macular edema should be treated once it becomes clinically significant. CSME is diagnosed if the patient has at least one of the following criteria (Friedman 2009):

  • Retinal thickening within 500 µm of the fovea
  • Hard exudates within 500 µm of the fovea with adjacent thickening
  • Retinal thickening ≥1500 µm in diameter within 1500 µm of the fovea

The optic disc measures 1500 µm in diameter on average and can be used to estimate distances along the retina.

Vitrectomy should be performed when a vitreous hemorrhage fails to resolve after 6 months or after 1 month in type 1 diabetics (Meredith 1998). The procedure is also indicated for certain tractional retinal detachments.

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last updated: 09-01-2010

Vislisel J, Oetting T.
Diabetic Retinopathy: from one medical student to another. Sept. 1, 2010; Available from:

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