[Spectral domain OCT in eyes with retinal artery occlusion]

Retinal artery occlusions are a straightforward, essentially clinical diagnosis. The role of spectral domain ocular coherence tomography (SD-OCT) in this condition is not well described.

Anoxic retinal edema develops in the acute phase of retinal artery occlusion (RAO) followed by a regressive phase giving way to retinal atrophy. The purpose of the study was to determine dynamics of theses retinal changes in central retinal artery occlusion (CRAO) and branch retinal artery occlusion (BRAO) using spectral domain optical coherence tomography (SD-OCT).

A prospective study of patients hospitalized at Hôpital Edouard-Herriot de Lyon between June and September 2009 was performed after patient education and informed consent. Retinal thickness of patients with central retinal artery occlusion (CRAO), branch retinal artery occlusion (BRAO) or cilio-retinal artery occlusion was measured centered on the macula or on the site of occlusion with spectral domain optical coherence tomography (SD-OCT) using Cirrus(®) (Carl Zeiss Meditec, Germany) upon admission, throughout hospitalization, at 1 month and at 3 months. Thickness and reflectivity of the various retinal layers were compared with the fellow eye.

Fourteen patients were included (seven CRAO, six BRAO and one cilio-retinal artery occlusion). SD-OCT in the acute phase showed retinal thickening and increased reflectivity confined to the inner retinal layers supplied by the retinal circulation with decreased reflectivity from the photoreceptor and retinal pigment epithelial layers secondary to a shadowing effect in the affected area. These changes subsequently resolved at 1 month and gave way to a marked thinning of the inner retinal layers by 3 months. In one case of CRAO associated with an ophthalmic artery occlusion and consequent occlusion of the ciliary circulation as well, initial OCT revealed complete retinal thickening involving both the inner and outer layers.

This study demonstrates that the anoxic intracellular edema resulting from retinal artery occlusions (RAO) observed histologically appears on OCT as a thickening of the inner retinal layers in the acute stage of the condition, giving way to atrophic areas starting at approximately 1 month ("pseudonormalization") and becoming clearly atrophic at 3 months.

SD-OCT is useful in the diagnosis of RAO, especially if the patient is seen later in the disease process, when the ischemic retinal whitening is no longer present on fundus exam.