Retinal venular calibre predicts ranibizumab vision improvement

By Shreeya Nanda, Senior medwireNews Reporter

Retinal venular calibre may predict visual outcome in diabetic macular oedema patients given the anti-vascular endothelial growth factor (VEGF) monoclonal antibody ranibizumab, a pilot study suggests.

Factors predictive of the response to ranibizumab in this patient population are currently not known, but previous research indicates that retinal vascular calibre could be one such factor, say Quan Nguyen (University of Nebraska Medical Centre, Omaha, USA) and colleagues.

This study used data from individuals with diabetic macular oedema who received intravitreal ranibizumab, either alone or together with laser treatment, in the phase II READ-2 trial.

Using optic disc-centred fundus photographs, the researchers calculated the baseline central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE), defined as the mean vessel calibre of the six largest arterioles and venules, respectively, in an area one-half to one-disc diameter from the optic disc margin.

And best-corrected visual acuity was assessed at baseline and a year after ranibizumab therapy using the Early Treatment of Diabetic Retinopathy Study chart.

Following treatment, 10 eyes from the same number of patients showed moderate improvement in vision, defined as a minimum two-line gain. These eyes had a significantly wider baseline CRVE than the 25 eyes from as many individuals whose vision did not improve moderately, at 248.3 µm versus 226.6 µm.

By contrast, baseline CRAE did not vary significantly between the participants whose visual acuity did and did not improve.

Nguyen et al propose that retinal specialists could use CRVE to predict visual improvement after intravitreal ranibizumab treatment in patients with diabetic macular oedema.

But they add in Eye: “Further prospective studies with a larger sample size and a broader range of disease severity and visual acuity are needed to confirm this finding.”

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