Distinct DME patterns seen on OCT

Optical coherence tomography (OCT) is valuable in managing diabetic macular oedema (DME), more so than fluorescein angiography, in which the degree of leakage is not correlated with visual acuity and outcomes, according to Peter Kaiser, MD. In addition, angiography does not show vitreoretinal abnormalities that may require a different treatment.

OCT provides a retinal thickness map that correlates well with leakage clinically, fluorescein leakage, and more importantly, with decreased visual acuity. The maps can be used to track progression and treatment efficacy, according to Dr Kaiser, of the Cole Eye Institute, Cleveland Clinic, Ohio, US.

The OCT single scan tomograms identify specific morphologic patterns in patients with DME; these six different patterns indicate different prognoses, requiring different management.

The sponge-like pattern is the one most commonly seen in which the inner layers of the retina appear to be compressed as the result of fluid absorption, and which responds well to laser treatment.

Cystoid macular oedema, characterized by cysts that grow and coalesce and are associated with worse visual acuity than with the sponge-like pattern, responds to steroids and anti-VEGF drugs.

Serous retinal detachment without posterior hyaloidal traction is characterized by serous fluid in the fovea not seen on ophthalmoscopy; treatment and absorption of the fluid often leads to the hard exudates deposits in the subretinal space.

Posterior hyaloidal traction leading to DME seems to be a distinct subgroup of patients. The traction is subtle but can be identified by sheen on clinical examination. Traction can cause a traction retinal detachment in a few patients. If there is traction that is more tangential resulting from the hyaloidal traction, it can be very subtle.

A retinal detachment can occur without traction; this does not respond to laser or medical therapy but requires vitrectomy.