Novel device tests suitability of lens implants

Researchers in Spain have developed a hand-held device to help patients with cataracts visualize how the world would look depending on the type of artificial lens they get implanted.

The device, dubbed the simultaneous vision simulator or simply SimVis, allows patients to experience an implanted lens’ effect on their vision before surgery, according to a statement. There has been a proliferation of intraocular lenses in the past decade to replace lenses clouded by cataracts. Some correct only far vision, requiring patients to wear glasses to correct their near vision, while multifocal lenses correct both near and far vision, but with some image quality and contrast tradeoffs, according to the statement.

"Currently, the decision on which intraocular lens is implanted during cataract surgery is typically based on the explanations and experience of the surgeon," said Carlos Dorronsoro, first author of the paper, in the statement. But because it’s difficult to translate a surgeon’s descriptions into an imagined visual experience, it is difficult for patients to make the decision, he said.

SimVis comprises an optoelectronic tunable lens that changes its shape when an electric current is applied, the researchers said in the statement. It simulates multifocal lenses by changing its shape back and forth quickly enough that human vision can perceive it. This allows a patient looking through the device to see near and far distances in focus, while also getting the loss of image quality and contrast.

The study involved 9 patients, who used the device to compare 7 different lenses. They looked through the SimVis at a poster, a laptop, a tablet and a smartphone, with text and eye charts at different distances, according to the statement. They then said which corrections they preferred.

"The favored or rejected lenses were different for different testers, suggesting the need for this kind of simulation prior to surgery to customize the selection of lenses according to patient requirements," Dorronsoro said in the statement. "Clinical use of the SimVis could provide an evidence-based way to assess the subjective needs and preferences of patients before they undergo cataract surgery."

- here's the statement

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