This condition is more common in older, non-insulin dependent diabetics, and is the most common cause of gradual loss of vision in a patient with non-proliferative diabetic retinopathy.
- this involves
- the breakdown of the blood–retinal barrier
- leakage of plasma from small blood vessels in the macula
- swelling of the central retina
- formation of hard exudates
- diabetic macular oedema (2)
- does not cause total blindness (1)
- leads to severe loss of central vision (1)
- most common presenting clinical symptom is blurred vision
- other symptoms can include metamorphopsia (distortion of visual image), floaters, change in contrast sensitivity, photophobia (visual intolerance to light), changes in color vision, and scotomas (localized defects of visual field)
- clinically significant macular oedema is
- retinal thickening and/or
- adjacent hard exudates that either involve the center of the macula
Four types of diabetic maculopathy are recognised:
- cystoid:
- characterised by microaneurysms and haemorrhages but relatively few, if any, hard exudates
- the main feature is extensive macular oedema which if persistent, may lead to a lamellar hole at the fovea with permanent impairment of visual acuity
- focal - a background diabetic retinopathy, associated with macular oedema and surrounding hard exudates
- ischaemic - similar ophthalmic picture to cystoid and differentiated from it by fluorescein angiography
- mixed - exudates, oedema and ischaemia
Reference:
- Frank RN. Diabetic Retinopathy.N Engl J Med 2004;350:48.
- Rittiphairoj T, Mir TA, Li T, Virgili G. Intravitreal steroids for macular edema in diabetes. Cochrane Database of Systematic Reviews 2020, Issue 11. Art. No.: CD005656. DOI: 10.1002/14651858.CD005656.pub3.