OCT angiography shows promise in CNV detection

By Shreeya Nanda, Senior medwireNews Reporter

Noninvasive optical coherence tomography angiography (OCTA) can successfully detect choroidal neovascularisation (CNV), research findings indicate.

Compared with the gold standard fluorescein angiography, OCTA had high specificity but low sensitivity, suggesting that the technique may be better suited to “following up CNV over time than for screening for undiagnosed CNV”, say the researchers.

This review of medical records included 61 patients (72 eyes) who underwent OCTA using the prototype AngioVue OCTA system (Optovue, Inc, Fremont, California, USA) between August and October 2014 at a US retina centre. To evaluate the sensitivity and specificity of OCTA, the team used an overlapping cohort of 24 participants (30 eyes) with suspected CNV who underwent OCTA and fluorescein angiography on the same day.

Using OCTA, CNV was detected in 48 eyes of 43 patients, while 24 eyes of 18 patients were deemed free of CNV.

Of the 31 eyes with CNV associated with neovascular age-related macular degeneration, the size of the CNV in 23%, 42% and 35% of eyes was small, medium and large, respectively. CNV size was defined as lesions with a greatest linear dimension smaller than 1 mm, between 1 and 2 mm and larger than 2 mm, respectively.

In the seven eyes with CNV linked to central serous chorioretinopathy, the CNV was small in 71% of eyes and large in 29%. And in the remaining 10 eyes with CNV associated with other diagnoses, CNVs were small, medium and large in 50%, 20% and 30% of eyes, respectively.

OCTA was “useful in localizing and measuring the size of the CNV”, Nadia Waheed (New England Eye Center at Tufts Medical Center, Boston, Massachusetts, USA) and co-workers write in Ophthalmology, adding that the ability to visualise changes longitudinally, “may lead to a decreasing necessity to rely on more invasive imaging techniques such as [fluorescein angiography]”.

Moreover, OCTA detected CNV in four of the eight eyes found to be positive for CNV by fluorescein angiography, giving a sensitivity of 50%. And of the 22 eyes considered CNV free as per fluorescein angiography, 20 were also determined to be negative for CNV by OCTA, equating to a specificity of 91%.

Waheed et al suggest that, in light of this high specificity, OCTA “could be a useful technique to confirm the presence of CNV when other methods are equivocal”.

They add: “Future studies with more varied patient demographics and larger sample sizes for higher-powered sensitivity and specificity determinations are necessary to evaluate the robustness of this technique with various types of CNV.”

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