Christy Sheehy, PhD, chief executive officer and cofounder of C. Light Technologies, talked about the FDA clearance of Retitrack—retinal eye-movement monitor—and how the device holds promise for facilitating more accurate ocular motor assessments at bedside.
Degenerative disorders in neurology and ophthalmology have interconnected biological and pathophysiological foundations.1 A tool that providers can use in their clinical practice to assess ocular motor function among patients with neurologic or ophthalmic diseases is the Retitrack, a monocular, tabletop eye movement monitor. The device is intended for recording, viewing, measuring, and analyzing temporal characteristics of fixation and saccadic responses when viewing a visual stimulus.
In recent news, C. Light Technologies announced it received 510(k) FDA clearance for the Retitrack, making it the first retinal eye-movement monitor cleared for use in the healthcare field. According to a statement, the clearance marks an important achievement for healthcare providers, allowing for a new understanding and perspective into oculomotor function via the retina to provide actionable and objective metrics.2
Recently, Christy Sheehy, PhD, chief executive officer and cofounder of C Light Technologies, sat down in an interview with NeurologyLive® to discuss more about the function of the device and her reaction to FDA clearance. She talked about how the retinal eye movement monitor operates and the types of eye movements that can be quantified by the device. She also spoke about the potential applications of the Retitrack device in clinical settings and the medical communities that could benefit from its use. Additionally, Sheehy elaborated on the advantages of using retinal video analysis over traditional pupil trackers for measuring functional eye motion.
The Retitrack is the first retinal eye-movement monitor and was designed to assess and analyze oculomotor function. Healthcare providers and their care teams are now able take videos of the back of the eye (the retina) to record and analyze temporal characteristics of eye movement data: saccades and fixation. Saccades are rapid, voluntary movements of the eye that abruptly move back and forth, such as the task of looking at my finger and then looking at my nose. We also quantify involuntary movements of the eye called fixational eye motion. Using the Retitrack provides new insights and understanding into ocular motor function for clinicians by quantifying both movements via the retina.
The Retitrack has both hardware and software components and operates by recording 10-second retinal videos. These 5-degree field-of-view videos visualize retinal structure at the cone photoreceptor level— the tiny cells in the back of the eye that help us see color. These structures are micron-level in size, and we lock on to them, as well as capillaries and blood vessels, to quantify eye motion down to roughly 0.1 degrees. The accompanying software then extracts the eye movement data from these videos. For the fixation task, that would be microsaccades and drift metrics. For the active task, it would be horizontal saccade characteristics. In real time, we can then generate a comprehensive report for healthcare providers to interpret and aid their clinical decisions.
For any clinician that is currently performing the “look at my finger, look at my nose” or “the follow my finger test” at bedside, they are ultimately performing an eye-tracking or oculomotor assessment. We can typically see this type of bedside exam being done in neurology, the neuro-ophthalmology, and optometry communities, and even in the ER. In essence, we take that subjective bedside ocular motor exam, quantify its movement, and provide objective metrics for the clinician to interpret. In addition, we also provide quantitative information regarding fixation, which would otherwise be invisible at bedside.
The indication that we are cleared for right now is for general eye movement monitoring of saccades and fixation, allowing the clinician to interpret the data. Our long-term company vision is to pursue additional indications for use in evaluating eye motion in neurological conditions. We are actively looking to partner with pharma, clinical research organizations, and care centers to research and validate device performance for new indications in order to achieve accompanying FDA clearances for each condition.
We've had the opportunity to observe the practical application of our device in clinical research, spanning from basic scientific investigations to exploratory endpoint trials.As for some research C. Light has internally accomplished to-date, we have conducted validation studies for our FDA clearance with human subjects showing that we can measure saccadic eye motion and fixation both accurately and repeatedly. We were also able to compare that data to existing pupil trackers, which are more common in the commercial eye-tracking world. These are eye-trackers that use the front of the eye (pupil) to track how the eye moves. We plan to publish these results in the coming year.
To better understand some of the differences between pupil vs. retinal tracking, I’ll go into some quick examples. First, when using the retina to track, a user no longer needs to perform screen-based calibration for each new patient. This process can be time consuming, where individuals look at 9 points on a screen, and pupil-tracking software needs to correlate how the front of the eye is moving with respect to a target on the screen. This method can be error-prone when you have a patient with a neurological or ocular motor conditions, for example. Second, pupils are dynamic and ever-changing: the size of the pupil can change during recordings based on variables such as lighting, emotional excitement, or disease. This can also pose issues in finding the pupil centroid, or the center of the pupil, which is required to track. The use of the retina gives an unambiguous record of where the eye is looking and what part of the eye is being used to view a target, with no patient calibration required.
We're the first retinal eye movement monitor cleared for marketing by the FDA—a very exciting achievement for C. Light Technologies. I think one of the most groundbreaking things we provide clinically is fixational eye motion quantification. These are microscopic eye movements on average less than ½ a degree (or <150 microns) in size and can impact how a person perceives the outside world. If a patient’s eye moves too much during fixation, the world can appear “jittery” or “unstable”; and if the eye doesn’t move enough, the patient can experience visual fading. We provide metrics that show speed, stability, amplitude, and direction of movement, etc., which provide a clinician with objective data to determine if oculomotor deficits are the primary culprit of a patient’s reported symptoms. I think it's a great opportunity for us to quantify metrics that would otherwise be completely invisible to a clinician, ultimately giving the patient experience a new voice. To me, that is extremely powerful.
One of our big company visions for the future is to provide advanced analytics to make our approach AI-driven, specifically being able to combine an AI or ML (machine learning) approach to our large eye motion data sets. That's something we are working towards for future iterations of our software and devices. We areacutely aware of the substantial impact this approach is poised to make and are excited to lead this endeavor for healthcare.
I think re-iterating how important eye motion is for patient health is one of the plugs that we always love to give. The efferent visual pathway in the brain is responsible for making eye movements. With this pathway innervating all 4 lobes of the brain, signals have to be coordinated in order to make an eye movement of the right size, the right speed, and at the right time. Having an objective way to observe oculomotor function on a clinical readout report will empower clinicians and save their valuable time, moving away from, “follow my finger; look at my finger; look at my nose,” to our novel device metrics.
The other big piece of information that we’re excited to share of course is that our device, the Retitrack, is officially for sale. Now that we are 510(k) FDA cleared for marketing, we are available for sale in the US. We'd love to connect with early adopters in the clinician community who share in our passion for furthering ocular motor health!
Transcript edited for clarity.