Virtual trial designed to explore AMD monitoring

February 3, 2016

Constructing vignettes from retina images and data can serve as a useful low-cost alternative to clinical trials for evaluating different screening approaches, researchers said. The researchers, from seven British medical centres, have taken this approach in a virtual trial to determine whether community optometrists can assess the risk that quiescent neovascular age-related macular degeneration (AMD) lesions can reawaken.

Constructing vignettes from retina images and data can serve as a useful low-cost alternative to clinical trials for evaluating different screening approaches, researchers said.

The researchers, from seven British medical centres, have taken this approach in a virtual trial to determine whether community optometrists can assess the risk that quiescent neovascular age-related macular degeneration (AMD) lesions can reawaken.

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They published their finding about the design of this trial, the Effectiveness of Community versus Hospital Eye Service (ECHoES), in the journal Eye. They have not yet published the results of the trial.

Following multiple injections of anti-vascular endothelial growth factor (VEGF) drugs, AMD lesions may become quiescent, but because they frequently reactivate, hospital ophthalmologists review them regularly.

Reviews take one of two approaches: Either they take place monthly-which is burdensome for patients; or practitioners continue to treat the patients while steadily extending the intervals between treatments-which increases costs.

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Community optometrists in the United Kingdom already have the training to recognize AMD, as they are responsible for the majority of referrals of AMD cases to the Hospital Eye Service (HES). Some have invested in equipment for colour fundus and optical coherence tomography (OCT) photography.

To test whether optometrists could screen for reactivated AMD, a randomised controlled trial could be ineffective because patients might not trust optometrists to do this work, the researchers speculated. In addition, these trials are expensive and time-consuming.

To see how well community optometrists could review quiescent AMD, the researchers provided a webinar training to 72 ophthalmologists and 83 optometrists.

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The researchers assembled a database from information collected for the IVAN trial of alternative treatments to inhibit VEGF. The database included images from the Network of Ophthalmic Reading Centres for the United Kingdom.

They used this data to create 288 vignettes representing patients with quiescent AMD being monitored for reactivation. Each vignette consisted of sets of colour fundus and OCT images from the study eye at two time points: “baseline” from when the lesions were quiescent and “index” from another clinical visit. The vignettes included clinical information such as visual acuity.

Three retina specialists evaluated the vignettes and established a reference standard for each index image. In the 28% of cases where they did not agree, they met to reach a consensus.

After participants took part in the webinars, the researchers asked them to assess 24 training vignettes each. If the participants could not correctly classify the lesion status for 18 of these vignettes, they were given a different set of 24 vignettes. If they could not correctly classify the lesion status of 18 of these vignettes, they were excluded from the trial.

Results

 

Out of the 56 ophthalmologists who completed the training, 48 passed the training test on the first attempt and two on the second attempt, but two withdrew afterward, leaving 48 ophthalmologists total.

Out of 61 optometrists who completed the training, 38 passed the training test on the first attempt and 11 passed on the second attempt, but 1 withdrew, leaving 48 optometrists total.

Those participants who passed the test in the training phase were asked to assess 42 different vignettes each. Each vignette was assessed seven times. Pairs of participants from each profession were assigned the same vignettes.

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The primary outcome of the study is to explore whether the participant agrees with the retina specialists’ determination of a lesion’s status. The researchers are comparing the number of these agreements between the two professions.

The study will also tally the number of potentially sight-threatening errors made by the participants, the participants’ judgments about lesion components (such as subretinal fluid and pigment epithelial detachment), and the participant’s own rating of their confidence about the primary outcome on a 5-point scale.

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The researchers are also conducting an economic analysis to see whether money could be saved if optometrists review patients for reactivated lesions.

The researchers concluded that this approach to analyzing different approaches to screening for AMD offers important advantages: Since participation took place entirely through a web-based application, the researchers were able to recruit participants quickly, and carry out the trial over a short period at a low cost, without risk to patients, they said.