VIS-OCT offers sight line

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The benefits of optical coherence tomography (OCT) have long been known as an imaging tool in ophthalmology, enabling the examination of the eye at microscopic resolution. But what may not be widely appreciated is that the use of visible light sources can improve upon the results of this well-developed technique in the detection and understanding of various eye-related diseases such as macular degeneration and glaucoma.

Doug FarmerWhile most commercial OCT and OCTA (angiography) systems use NIR light for economic and technical reasons, broadband visible light sources have expanded from 400 to 2000 nm or more. This has enabled the imaging of the complete vascular network and all five of the outer retinal layers. With resulting higher resolution and imaging contrasts at the tissue level generated with VIS-OCT made available to clinicians and researchers, conditions like blood oxygen saturation can be measured as never before.

In our cover story, professor Hao F. Zhang of Northwestern University and Kieren Patel, a founder of Opticent Health, reflect on the many possibilities for ophthalmology brought to the forefront with VIS-OCT. More investment in VIS-OCT is needed, they write, to bring down costs and excite clinicians about its application.

Also featured in this issue:

• In lens-free microscopy, a light source is placed right on top of an image sensor. An algorithm helps translate the pattern caught by the sensor to achieve enough resolution that the image can be studied and virtually dissected. Contributing editor Hank Hogan talks to experts in the field, who reveal that challenges remain to fully implementing lens-free microscopy in the laboratory and field. Without the need for lenses, the microscopes can be made smaller and less expensive than other types. Read more.

• Keeping with the core technologies of microscopy, guest authors Pablo Blinder, Lior Golgher, and Hagai Har-Gil of Tel Aviv University write that open-source photon counting can reveal details of a specimen while removing much of the noise. PySight, an open-source application, has been developed to implement this technology in standard microscopes, eliminating the need for extensive training or upgrades. Using a depth-scanning varifocal lens, researchers were able to acquire a large volume of images, capturing what is occurring in a specimen in real time. Read more.

• When searching for a suitable camera to take advantage of the dynamic developments within the spectrum of fluorescence microscopy, prospective buyers should consider a number of factors, Felix Asche of Basler points out. Basic choices — including optical format and resolution; CCD, CMOS, sCMOS, or BSI; monochrome or color; global shutter versus rolling shutter; sensitivity and dynamic range; image quality and noise; and cooling — all weigh on the search to acquire a camera for purposes in a range of industrial settings. Asche explains that with SONY’s discontinuation of CCD camera components, opportunities exist for companies to chart new ground in the life sciences. Get an inside look at some of these changes.

• And in our “Biopinion” for this issue, Jasmin Schaefer, Iain Johnson, and Claudia Jaffe of Lumencor Inc. examine the need for strong, high-quality light sources for microscopy, a feature they argue is too often overlooked in medical and industrial applications. Solid-state lighting has been available for the last half-century, they point out, but there are many medical and manufacturing settings where, for whatever reason, it has not been embraced. With the right light source, test results can prove to be more reliable and less expensive at the same time. Learn more about the authors’ perspectives.

Enjoy the issue!

Published: September 2019

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