Visual System

Medical Device Monday: Artificial Intelligence to Detect Vision Loss in Diabetic Adults

Today’s science and technology is truly beginning to look like a SciFi movie: robots and medical devices with artificial intelligence performing tests and tasks to help make new discoveries and form conclusions that we might not be able to. We— as humans— can only do so much, but with the help of new, smarter medical devices, we can make more discoveries, improve diagnoses, and enhance a patient's quality of life. Artificial intelligence (AI) is a technology that uses algorithms and software to interpret complex data without human help, and is something that has definitely been on the medical horizon for a while. Thanks to the Breakthrough Devices Pathway (defined in a Wednesday Wisdom earlier this month), a new medical device has just been granted by the FDA that will help millions of patients.

IDx-DR is a device recently granted via the de novo pathway, and is geared towards adults with diabetes who run the risk of vision loss. There are more than 30 million adults living with diabetes in the US today, and one of the risks that comes with diabetes is vision loss, or diabetic retinopathy. Diabetic retinopathy is the most common cause of vision loss among adults with diabetes, and occurs when high blood sugar levels lead to swelling and leakage of blood vessels in the retina. There are two stages of diabetic retinopathy: the initial stage is called the Non-Proliferative Diabetic Retinopathy (NPDR) and the advanced stage is called the Proliferative Diabetic Retinopathy (PDR) which can lead to blindness. In NPDR, the tiny blood vessels weaken and can leak blood and fluid into the retina. Sometimes the blood vessels close and blood cannot reach the macula; these events lead to a blurry vision. In PDR, damaged vessels eventually close off leading to the growth of new, abnormal blood vessels in the retina. These new blood vessels can also be leaky...leading to an imbalance of the normal flow of fluid out of the eye...leading to pressure build up and eventual optic nerve damage. Additionally, the scar tissue stimulated by the growth of new blood vessels may lead to retinal detachment. IDx-DR is the first medical device to use artificial intelligence to detect higher levels of retinopathy in diabetic adults, and is a medical device developed to discover and detect these indicators to prevent vision loss.

Early detection of diabetic retinopathy is very critical in preventing vision loss, and this new medical device is one that works to make early detection more common, ultimately cutting down the percentage of diabetic adults that lose vision from diabetic retinopathy. The current mode of diagnosis involves a visit to the ophthalmologist who will either do a fluorescein angiography— where a yellow dye is injected to see what is happening with the retina— or an Optical Coherence Tomography (OCT) to measure the thickness of the retina.

Compared to these modes of diagnosis, IDx-DR promises to provide an immediate, reliable assessment for diabetic retinopathy which can be used even at a primary care physician’s office. One of the great things about it is you don’t have to be a rocket scientist to use it! It is designed to be user-friendly, and can be administered by trained novice operators who have no prior experience with ocular imaging.

Don’t believe me? Let’s figure out how this thing actually works...

Using a Topcon NW400 camera, the operator captures images of the retina. The retinal images are then uploaded onto a computer where the IDx-DR software is installed. The IDx-DR software then analyzes retinal images using algorithm to detect signs of retinopathy.  In less than a minute, the operator will receive a results report with one of the three outputs:

a.       Exam quality is insufficient if the images are of low quality

b.      Negative for more than mild diabetic retinopathy. Retest in 12 months.

c.       More than mild diabetic retinopathy detected. Refer to an eye care professional.

In a 2017 clinical study, IDx-DR was tested on 900 diabetic patients across 10 sites in the US. IDx-DR was successful in detecting mild diabetic retinopathy with 87% sensitivity and 90% specificity. That’s pretty awesome! Unfortunately, IDx-DR cannot be used on patients who already have vision loss, blurred vision, or floaters. It is also contraindicated in patients diagnosed with other eye issues, like macular edema, severe non-proliferative retinopathy, proliferative retinopathy, radiation retinopathy, or retinal vein occlusion. Finally, IDx-DR can be used to only detect diabetic retinopathy and not any other ophthalmic diseases.

With an estimated 24,000 people who go blind from diabetic retinopathy each year due to lack of screening, IDx-DR promises to be a novel device in managing diabetic retinopathy. The benefit of this device far outweighs the risk and we're excited to see it come to market!  

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Med Device Monday: Raindrop Vision Inlay

Presbyopia is a fancy (okay, medical) way of saying farsightedness, meaning the ability to see things at a distance, but difficulty seeing or reading things up close. It's caused by aging-related loss of elasticity in the lens of the eye. We've all seen someone of a certain age hold a menu or a price tag or a recipe at arm's length in order to read it. The next time you see this happen, take note! These eyes have been places and seen things–to wit, presbyopia is the Greek word for "old eye". This quick, 30-second video from the American Academy of Ophthalmology is a good primer for understanding this condition and a futuristic new device that might make that unnecessary arm-length-reading a thing of the past.

Essentially, the lens in our eye must change shape in order for us to read text up close. As we age, the lens thickens and becomes less elastic, making this change more difficult to accomplish. Raindrop Near Vision Inlay is a medical device that received FDA approval in 2016, and aims to fix this. 

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This innovative, implantable contact lens is made of 77% water and is placed through a quick, LASIK-like procedure. It works by reshaping the front of the eye to allow for up-close reading. Per FDA, "The safety and effectiveness of the Raindrop Near Vision Inlay were studied in a clinical trial of 373 subjects implanted with the device. Two years after implantation, 92 percent of patients included in the analysis (336 out of 364) were able to see with 20/40 vision or better at near distances with the inlay-implanted eye."

Other reported results also look strong:

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This type of device—one that gives a longterm solution to an every day problem—is one of the many beautiful things medical devices can do. I recommend checking out the Raindrop Inlay manufacturer's website. They do an exceptional job of illustrating the daily hassle that comes with this medical condition and makes it easy for anyone to imagine what it would be like, even if they don't (yet!) have to contend with it. I look forward to following this product.


Further Reading:

Raindrop Near Vision Inlay Approval Letter

Summary of Safety and Effectiveness Data


Med Device Monday: Triggerfish

Glaucoma is a term used to describe a group of diseases of the eye and optic nerve which, if left untreated, can lead to blindness or loss of vision. Once vision loss sets in, it cannot be recovered. While there is no cure for glaucoma, with early detection and treatment it can be managed and these side effects can be mitigated, delayed, or even avoided.

Managing the disease has to do with managing or alleviating pressure in the eye. 

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The National Eye Institute explains, "Several large studies have shown that eye pressure is a major risk factor for optic nerve damage. In the front of the eye is a space called the anterior chamber. A clear fluid flows continuously in and out of the chamber and nourishes nearby tissues. The fluid leaves the chamber at the open angle where the cornea and iris meet. (See diagram below.) When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye.

In open-angle glaucoma, even though the drainage angle is “open”, the fluid passes too slowly through the meshwork drain. Since the fluid builds up, the pressure inside the eye rises to a level that may damage the optic nerve. When the optic nerve is damaged from increased pressure, open-angle glaucoma-and vision loss—may result. That’s why controlling pressure inside the eye is important."

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So if managing pressure is key, then so must be monitoring it. 

Enter the Triggerfish "smart" contact lens. (If looking at this doesn't make you feel like you're living in the future, I don't know what will.)

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While traditional methods of monitoring pressure in the eye meant taking a measurement during a visit to your eye doctor, Triggerfish is a soft contact lens that monitors pressure in the eye over a 24-hour period, providing insight into changes and peaks in pressure throughout the day. The type, timing, and dose of medication (like pressure-mitigating eye drops) can then be more precisely prescribed for the patient. Personalizing and targeting precise treatment in this way is then of course more likely to lead to a better outcome.

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An article from VisionAware (part of the American Foundation for the Blind) explains, "The Triggerfish® lens is a sensor that monitors changes in the curvature of the cornea, the transparent dome-shaped tissue that forms the front part of the eye. According to Sensimed, these changes in the cornea correspond directly to fluctuations in intraocular pressure, which is characteristic of certain types of glaucoma.

Eye pressure data from the Triggerfish® lens is transmitted wirelessly to a small adhesive antenna placed on the face near the eye. The antenna then transmits the data to a portable recorder worn by the patient. The lens can be worn continuously for one 24-hour period...When the patient returns to his or her eye doctor, the data is transferred from the recorder to the doctor's computer via Bluetooth technology for immediate analysis."

The article's editor then goes on to note that recent studies have shown that pressure is often lowest during waking hours, when patients are most likely to see their doctors, and highest at night–thus making this information that much more valuable in crafting a treatment plan.

I absolutely love this type of personalized medicine: it's a win for patients and healthcare providers alike. Being able to tailor a care plan to a patient's specific experience and needs not only means that their vision is more likely to be preserved, but it is also more efficient by cutting back on the number of doctor's appointments for evaluation and treatment adjustments. Triggerfish is one more reason I'm excited to be living in the medical future!


Further reading:

FDA's Triggerfish Classification Order

FDA's Triggerfish Decision Summary

Med Device Monday: LASIK Study

LASIK is a well-known surgery that's not quite new. Designed to correct eyesight and eliminate or reduce the need for daily contact lenses or glasses, it was approved by FDA in 1999. LASIK (Laser-Assister In Situ Keratomileusis) works by permanently changing the shape of the cornea in order to alter vision. It is of course meant to be a positive, life-changing medical procedure, but as with any procedure or medical device, it is not without risk. 

This video is a bit dry, but it outlines the procedure, its intended outcome, and the associated risks:

In 2009, ten years after LASIK was granted by FDA, the National Eye Institute (NEI) and the Department of Defense (DoD) began working together on something called the LASIK Quality of Life Collaboration Project (LQOLCP). This joint effort was designed to get a solid look at patient outcomes by speaking directly with patients both before and after their procedures. In other words, the study sought to determine not just a level of satisfaction, but a relative level of satisfaction. And of course, this helps inform labelling and patient expectations when considering the surgery. The program itself sums it up:

"The project aimed to develop a tool to determine the percent of patients who develop difficulties performing their usual activities following LASIK, and to identify predictors for those patients.

At the time we developed our project, there was a limited amount of valid scientific data on certain patient-reported outcomes (PROs) related to LASIK. A PRO is a report of a condition experienced and reported by the patient, not the health care provider.

Most LASIK studies used tools, such as questionnaires, to assess visual symptoms, but only after the surgery. The Patient-Reported Outcomes with LASIK (PROWL) studies in the LQOLCP assessed visual symptoms both before and after their LASIK surgery to identify changes over time. The studies also measured the impact symptoms directly had on performing usual activities, which had not previously been done."

Various steps were taken in this study, which you can read about in detail in the link above. The study began in 2011 with patients who were contemplating LASIK surgery. Patients were interviewed and asked to complete carefully researched and conducted surveys designed to gauge their pre-surgery feelings and experience. In 2014, the second half of the study began: one part was conducted in the civilian population, and the other right here in San Diego at the Balboa Naval Hospital. The study helped establish new measurements of success and side effects for the procedure: " scales that can be used to more thoroughly assess candidates' symptoms before LASIK surgery, monitor them for visual symptoms as well as satisfaction after LASIK surgery, and measure the impact any post-LASIK symptoms have on a patient's ability to function." What the studies found is that LASIK is generally quite successful in terms of both results and patient satisfaction. Check out the details below:

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While careful planning and testing of devices is essential to get FDA approval and get your device to market, it's certainly satisfying to see a follow-up study showing that the procedure is still successful–particularly after it's been on the market for some time. It also makes sense to continue to evaluate the effectiveness and impact of a device in order to help inform patients who may consider it! 

For further reading on this topic:

FDA's LASIK information center

FDA-approved Lasers for PRK and Other Refractive Surgeries

FDA's role in LASIK

Med Device Monday: REBIScan

The earlier amblyopia (lazy eye) and strabismus (misaligned eyes, eyes that don't track together) can be detected and treated, the better the outcome for the patient. Both of these conditions can affect vision, balance, and depth perception, and if left untreated can lead to permanent blindness. And while both amblyopia and strabismus are fairly common in children, impacting up to 5% of the population, most children do not routinely undergo visual screenings. While obvious cases of 'lazy' or misaligned eyes may be caught, these disorders are not always apparent to the observer, and without routine eye examinations up to 50% of these cases are missed in children. 

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REBIScan aims to bridge that gap with their Pediatric Vision Scanner (PVS): a handheld ocular scanning device that can detect both of these conditions. Additionally, early intervention and treatment may not just be more effective, but may also prove to save costs. According to REBIScan's website, "Researchers estimate that the direct cost of the conditions in America is over $1 billion per year. This is related to both missed diagnoses (leading to longer and costlier follow up examinations) and referrals of healthy children to specialists (resulting in wasted insurance...[spending]...and patient co-pays.) In America, approximately half of all cases are missed. Globally, it is estimated that 35-40 million children are affected by the condition." An easy-to-use device that streamlines improves the healthcare process and makes for better outcomes? Sounds like a win to me.

Recently approved via the de novo pathway, the PVS is roughly 94% effective at detecting these conditions in children. Per the de novo classification request "The Pediatric Vision Scanner is intended for the automated detection of misalignment of the visual axes using polarized light. It is indicated for the screening of amblyopia and micro strabismus associated with amblyopia in children age 2 to 8 undergoing evaluation in a professional eye care setting and who are responsive to taking direction and who can pay attention for at least 5 seconds." 

FDA's Evaluation of Automatic Class III Designation (de novo request) is here.

Read REBIScan's press release here.

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