Researchers devise a better way to potentially avert blindness due to diabetic retinopathy

(c) USC Translational Imaging Center

Researchers have developed a new non-invasive technique that images the retina to quickly screen patients for diabetic retinopathy.

More than 7.7 Americans suffer from diabetic retinopathy, the leading cause of blindness in American adults, according to the National Eye Institute at the National Institutes of Health. However, current diagnostic methods are invasive and inconvenient, causing half of afflicted patients to forgo eye exams, oblivious to their advancing disease until it’s too late to receive sufficient treatment.

Researchers in the Translational Imaging Center, a joint venture between the USC Dornsife College of Letters, Arts and Sciences and the USC Viterbi School of Engineering, are improving optical coherence tomography (OCT), a system that quickly and non-invasively images the retina to simplify the diabetic retinopathy screening process.

Scott Fraser, Provost Professor at USC Dornsife, Children’s Hospital Los Angeles, the Keck School of Medicine of USC and USC Viterbi, and Jeff Fingler, senior scientist at the Translational Imaging Center, are leading the work, which could help the 50 percent of unidentified patients begin treatment earlier while simultaneously easing the workload of busy ophthalmologists.

The authors point out that with increasing number of patients with diabetes, but with no corresponding increase in retinal specialists or ophthalmologists, majority of these patients are not being screenings often enough. Which lead them to take up this work.

Diabetic retinopathy can result in vision loss from retinal damage. When screening patients for it, doctors must check for any changes in blood vessels, including leakage, swelling, missing vessels or growths.

(c) http://www.opsweb.org

Traditionally, patients are diagnosed using fluorescein angiography, which is a drawn-out lengthy and invasive process. Patients are injected intravenously with fluorescein, a dye that makes their blood brightly fluorescent, so their blood vessels glow green when illuminated with a blue light. After the dye reaches the eye, the subject must stare into an instrument that subjects them to bright flashes of blue light for several minutes. Fluorescein angiography’s combination of bright flashes and eye dilation impacts patients’ vision for the rest of the day.

Fluorescein angiography has been used for over 50 years, but being expensive, complicated and too invasive to be used as a screening tool, retinal specialists usually recommend it for people who they suspect have retinal changes, preventing them from catching people at the earliest stages of the disease. With diabetic retinopathy, catching the disease at the earliest stages is crucial. Most treatments cannot reverse the damage done by the disease; they only can prevent future damage. By making the screening process accessible to diabetic patients, who are at risk for diabetic retinopathy, Fingler’s and Fraser’s improved screening system will help more patients receive adequate treatment and save some from blindness.

Described by Fraser as “an optical equivalent of an ultrasound machine,” OCT was originally invented by Keck School of Medicine Dean Carmen A. Puliafito. Invisible, infrared light travels through an interferometer, which splits the light into two beams: one that is shined though the pupil and recollected after it reflects back from the retina; the other is bounced off a simple mirror. By comparing the two reflections with a spectrometer, which measures the color of the light, the image of a virtual slice through the retina is created.

The entire OCT-angiography process only requires seconds, compared with the fluorescein method’s 10 minutes, and it screens patients without the inconvenience of injections and dilations or the intense blue flashing light. The team hopes that the speed, comfort and simplicity of their screening process will increase the compliance of diabetic patients being screened for diabetic retinopathy.

Since OCT is already used by ophthalmologists all the time, the team wants to enhance the instrument so that it can easily become a more widely acceptable angiography method that is available to the masses. While OCT itself isn’t new, Fingler’s and Fraser’s idea for its application is.

The two hope to make OCT screening stations available in pharmacies, akin to blood pressure monitors frequently found in drug stores. This would effectively alleviate two major problems surrounding treatment of diabetic retinopathy. First, placing devices in local pharmacies would make screening easier, lessening the number of undiagnosed patients. Additionally, moving the screening process from doctor’s offices to pharmacies would give ophthalmologists more time to spend with higher-risk or already diagnosed patients — time that is increasingly valuable given the large gap between supply and demand of ophthalmologists.

Although there are currently more than 200,000 ophthalmologists worldwide, there is an anticipated shortage of ophthalmologists in both developed and developing countries, according to the International Council of Ophthalmology. Developing countries simply lack significant numbers of ophthalmologists; in developed countries, the population over 60 is growing at twice the rate of the growth in the ranks of ophthalmologists. This means more patients, without an adequate increase in doctors.

According to the team, taking the primary diagnostics out of the ophthalmologist’s office will allow doctors to spend more time actually treating the disease, instead of screening people who are actually healthy.

Minor modifications from the original source

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