Blog: Behind an FDA Clearance

An FDA clearance is necessary to market a medical device in the United States. Everyone is aware that regulatory hurdles can be an expensive, intrusive process. Having one carries a lot of weight. However, few companies have been through the process and rarely discuss the challenges. But there are benefits to transparency. Users of SyncThink technology deserve to know how objective measures enhance clinical judgment. The rules are in place to protect patients and improve care.

Let’s discuss three hurdles:

1) Efficacy

2) Safety

3) Quality



All medical devices carry an indication for use (IFU) – a statement of utility. The efficacy standard of a medical product is a basic guarantee that the product does what it says it’s going to do. The medical device manufacturer must demonstrate to the FDA that a product affects the IFU. For SyncThink’s EYE-SYNC, our IFU is:

The EYE-SYNC is intended for recording, viewing, and analyzing eye movements in support of identifying visual tracking impairment in human subjects.

To support this claim, SyncThink had to provide validation testing of our eye tracking performance. Eye tracking has not yet become a commoditized technology. In fact, most eye tracking is far less reliable than the technology built into EYE-SYNC, and none provides our performance in a mobile form factor. It is not particularly difficult to make an eye tracker, but it is exceedingly difficult to make an eye tracker that works well across all populations.

It’s further challenging to make this technology fast and easy to use. For all EYE-SYNC assessments, we make a live video of our infrared eye tracking cameras available to the clinician in real time. This serves several purposes:

– the clinician can monitor for compliance/malingering;

– it provides a subjective preview of user performance;

but most importantly, live video monitoring ensures that a user is within the eye tracking field of view, and that our eye tracking reference points – six reflections on the cornea – are as visible as possible during the assessment. Even with these tools, there is still going to be a small population that is difficult to capture. These are users with large or small inter-pupillary distance; hard or ill-fitting contact lenses; eyelid occlusion (i.e. double eyelid); and visual conditions like amblyopia (lazy eye), diplopia, etc. Some of these are contra-indications for EYE-SYNC. However, to mitigate confusion, we also provide a simple, automated quality assessment with every assessment result: Good, Fair, and Poor. These quality techniques have been developed under the guidance of eye tracking experts and thousands of clinical eye tracking results.

Most of SyncThink’s risk mitigations are directed towards a false positive reading: incorrect assessment of impairment in a healthy individual. We want to ensure that users receive the information they need to pursue their personal goals with confidence. However, the other type of failure, false negative, is far more important to ensure. No clinician wants to place an impaired individual in a potentially harmful situation. It’s this dangerous situation where eye tracking excels. We take thousands of individual measurements over the course of a 60-second EYE-SYNC assessment. A user simply cannot ‘luck’ into a high-performing eye tracking result. If a user tries to sandbag a baseline measure, they will look severely impaired.

Of course, eye tracking alone is useless without visual presentation. We have distilled decades of clinical research and experience into three important assessment paradigms for isolating and measuring modes of visual orientation:

1) Saccades: fixation performance of a motionless user with respect to a static world

2) Smooth Pursuit: visual synchronization of a motionless user with respect to a predictable, dynamic world

3) Vestibulo-ocular Reflex (VOR): visual synchronization of a moving user with respect to a static world

We use all three modes of orientation in conjunction as we navigate daily life. For high-risk activities in industry or sport, maintaining visual orientation is essential to avoid injury.



Medical devices are held to the same tenet of any medical practice: do no harm. All regulated medical devices undergo extensive safety testing. As a Class II device, EYE-SYNC is required to meet several standards.

IEC 60601-1 Part 1 Electrical Safety Testing: Since 1977, the International Electrotechnical Commission (IEC) has published general requirements for safety and essential performance of electrical medical equipment. Generally, IEC 60601-1 is designed to minimize the risk that a device will directly or indirectly harm the user. Battery standards and operational current are reviewed to ensure that users cannot be severely electrocuted or burned. The device workflow is also reviewed in the context of its IFU to ensure that electrical fault will not cause an inappropriate result or delay.

IEC 60601-1-2 Electromagnetic Disturbances: Our phones, computers, and gadgets coordinate with each other over intricate and resilient radio communications. It is one of the great magic in modern technology and it’s made possible through strict regulation. Poorly-designed devices could easily gum up our airwaves with noisy radio emission. The situation is even more sensitive in a medical environment, where those communications may be life-saving. IEC 60601-1-2 is a standard to ensure that medical devices emit quality radio signals at reasonable energy.

IEC 60601-2-57 Non-laser Light Sources: We’ve long understood that laser light can be a weapon in the hands of Bond villains. However, all colors of light can be a hazard with sufficient intensity. EYE-SYNC uses infrared lighting to provide consistent, adequate lighting for eye tracking analysis, without distracting the user. The limits imposed here are governed by an IEC 60601 supplemental standard. No worries, EYE-SYNC lighting comes nowhere near an intensity that might harm your eyes.

ISO 10993-1 Biocompatibility: No one should expect to receive a rash or infection from using of a medical device. International Organization for Standardization (ISO) detail a set of standards for device contact inside and outside of the body. Fortunately, EYE-SYNC is limited to skin contact.

Software Risk: Bugs are a routine part of computer-based technologies. Everyone has had an app crash or Windows display the Blue Screen of Death. These are annoying and careless, but usually harmless. However, as medical devices become increasingly complex and capable, the risk from software approaches consumer complexity. As part of SyncThink compliance, our engineers must regularly evaluate the risk of software failures and ensure that none will cause harm to our users.


Many consumer technologies undergo a rigorous quality assurance process. Materials and parts are included in the design, then procured and then tested for a conformity and reliability. Complex products may also have a serial number identifying the model, batch, and individual unit. These are best practices that we expect from consumer devices. None are a requirement. Some devices we purchase may come from parts unknown, but if it breaks, no harm was done. Better luck next time.

Medical devices conform to a higher standard. If something breaks, it may cause harm, and everyone involved will expect to know why. We hope that we’re never that situation, but if required, all EYE-SYNC devices can be traced back to their original components, build instructions, handlers, assemblies, and testing. Our quality program implements ISO 13485: Quality Management Systems for Medical Devices. If we find a faulty component in the field, we can trace that to a specific lot and vendor. If we receive a complaint, it’s documented, investigated, reviewed, and corrected. If our product changes, our documentation is revised and our team trained. If a product is returned, that device is quarantined, inspected, and thoroughly tested before returning to the field. Our quality program ensures that EYE-SYNC is built to the highest standard, and we’re continuously raising that bar.