Video Frenzel goggles

Timothy C. Hain, MD•Page last modified: March 2, 2021

Frenzel goggles are extremely useful in evaluation of patients with vestibular disorders. In their original incarnation as optical devices, they consist of the combination of magnifying glasses (+20 lenses placed in front of the patient), and a lighting system. When Frenzel's goggles are placed on the patient, and the room lights darkened, nystagmus can easily be seen because the patients eyes are well illuminated and magnified, and because fixation is removed as the patient can hardly focus through magnifying glasses on a dark room.

Things have changed. Now there are two types of Frenzel goggles -- optical and video. The video are far preferable, but they cost substantially more than the optical versions. This page is about the video ones only. Basic material about Frenzel goggles is on the optical Frenzel goggle page.

Video Frenzels are much better than optical Frenzels

In the authors practice in Chicago Illinois, we use video Frenzels. An image of the eye fills the entire screen of a 30 inch monitor. This allows one to see very small amounts of nystagmus from across the room.

Such video-eye movement recording systems, called "video Frenzels", are usually preferable to optical Frenzel goggles (Baba, 2004). Video systems provide a mechanism of recording the examination and also are more educational for patients, spouses and students. Video goggles eliminate vision entirely, compared to Frenzel goggles which merely obscure vision. They also provide the capability of showing much larger images. These are very important advantages.

Vendors of Video Frenzel Goggles

As of 2021, we have an odd situation where there is a large market for video Frenzel goggles, but the leader in the field (Micromedical Technology) stopped manufacturing their excellent "RealEyes" goggle. The biomedical engineering community seems to be gradually developing replacement devices for this situation where a vacuum was created. The reason that there is a large market for video Frenzel goggles is that the vestibular PT community has realized that there is great value in being able to monitor eye movements while treating the most common dizzy condition (BPPV), and there are a lot more PTs than there are physicians who are interested in testing for dizziness.

At this writing (2021), there are some "high end" video frenzel goggles, and some "low end" goggles, that just barely function. The proliferation of the low-end goggles now has blurred the usual rather easy distinction of "no frenzels", vs "video frenzels". Now one needs to consider -- no frenzels (most of the time), optical frenzels (much better), low-end video (about the same as optical), and high-end video. The rank order is:

 

We don't think that any of these devices is as good as the "RealEyes" goggle, but as the "RealEyes" is no longer being made, I will list them here anyway and provide contact information when available. My opinions are mainly based on video's that I have seen from these devices.

The features that a "good" video Frenzel goggle system should have includes:

1. Non-visible light illumination (infrared). While this should seem rather obvious, there are some devices out there that use visible light. This is not OK.
2. High spatial resolution -- the eye should (not the image of the eye and surrounding stuff) should be at least 400x400. Practically this means that either the eye should be close enough to the camera so it fills the camera's sensor (and focussed too !) , or that the camera has far higher resolution and one can have software crop the video. We don't know of any goggles that can do this aside from the Micromedical RealEyes (which is no longer being sold). So this is the big problem. One potential solution is to use a very high resolution camera (such as 4000x4000) and "crop" it in hardware before it reaches the PC. The devil is in the details of course.
3. Ability to allow one eye (or both) to view while other is being recorded. This means that one either needs a frame that can accept a monocular camera, or a mirror system allowing the eye to both be viewed and imaged. The goggles that do this are the Micromedical (no longer being sold), the Synapsis goggles, the Russian goggles, and the Nagashima goggles. Designs that don't allow this include the new "Vestibular first" goggle, and the Sercom goggles.
4. Reasonable time resolution -- the minimum is 30 frames/sec. This is quite easy with USB cameras, and also easily attainable with composite. So generally not an issue, but check -- what you should be looking for is dropped frames - -you play back the video, and it suddenly jumps. Don't buy these.
5. Focus -- the iris should be clear enough that torsion can be seen. Practically this means that there must be an easy way to adjust the focus from the outside. The most straightforward method is to move the camera in and out. Most of the goggles on this page cannot do this. The Micromedical RealEyes did this, and the Russian goggles have some focusing ability. We do not think anyone should buy goggles that can't function, given that they want to see what they are doing. This is a mostly unsolved problem (sadly). The high-res/hardware crop solution might be a way around this (see item #2).
6. Ability to accomodate to various shapes of faces and keep the camera on the eye. This can be done using a ball joint of or using very high resolution cameras. The Micromedical and Synapsys goggles have ball joints. As of 2019, we think that the high resolution camera is the better solution as there are less moving parts. We are not entirely sure, but we think that none of the current crop of goggles are high-res. Another problem for engineering to solve. The high-resolution/hardware crop solution (see item #2) might work.
7. Independent from computer -- a goggle system should not require you to carry around a computer. Practically this means that either the system should use a composite camera (rarely seen now), or have a USB storage system built into the system. There are a few USB goggle systems, such as the Sercom goggle, that have portable storage built in. This is a good idea for devices being carted around. We envision here a processing unit that does the hardware crop and stores on a local USB drive.
8. Light weight and difficult to break. This has to do with mechanical design. We have had patients tear off their goggles and throw them. The Micromedical Goggles are tough ! Goggles with mirrors are usually not so tough because you can break a mirror. Goggles that have video displays integrated into the goggle are obviously not going to withstand being thrown on the floor. One has to consider the whole package.
9. Reasonable price (right now, $3000 is the most we think anyone should pay). Prices are rather variable, but so far we don't think any of them are worth more than about $1500.
10. A "room cam". One needs to know what is going on, although not necessarily at as high speed as the eye . Usually this is attained through a 2nd camera in the room, called a "room cam". These are very cheap, but for the USB version, one needs a way of acquiring another stream of video. USB is not really a video standard, and it can get bogged down if your PC should, for example, start to download a Microsoft windows update, you might drop some frames. With a composite camera, it is totally impractical to convert two streams of video at the same time, and the usual methodology here is to use a PIP (picture in picture) converter, and then convert the whole thing. This has the good feature of adding a time stamp as well, but the bad feature of obscuring the eye. At this writing (2021) we are somewhat in favor of a high-res USB camera.
11. Hardware/software should not be proprietary and "locked down". This is somewhat difficult to find as companies that invest in these devices are hoping for return on their investment, and also the very limited market for these devices. Goggles that use composite cameras are intrinisically "open". There are not so many of these left however. The Nagashima and Sercom goggles are examples. The VENG vendors, such as MIcromedical for example, typically "lock down" their USB cameras. Perhaps this makes sense for a $20,000 VENG system, but we are a bit dubious that this makes sense for a mass-market $1500 device. The DIY goggles are, of course, open.
12. FDA and CE approval. Many of these devices are from other countries than the US and not all of these devices are FDA or CE approved. Although there are few safety issues to consider, still this may impact one's ability to use them in a clinical setting. Regarding safety issues, we would be mainly interested in the intensity of the IR illumination. It is difficult to imagine any other safety concern.
13. Portability -- one that hooks up to an Ipad or cell phone for video display would be ideal. Of the devices on this page, the Australian device claims this capability. We have seen devices that have the video display on the goggle itself. We think this is not very wise.

List of goggles shown below: (other vendors -- email me and I will add on your device)

• Do it yourself
• Micromedical (no longer sold)
• Nagashima (Japan)
• Russian (probably the best design in 2019)
• Sercom (Argentina) -- a little large
• Synapsis (France)
• Vestibular First (USA) -- a little large.
• Vesticam (Australia).

We are not including VENG systems here that can be used as Frenzel goggles, as these are generally much more expensive, and we don't see why one needs to pay $5-20,000 for a webcam in a goggle.

Synapsis Video Frenzel goggles

Synapsis is a French company that sells VENG equipment in Europe. Their equipment is particularly friendly to recording children, but it is not as well designed for adults. Unusual features of the Synapsis goggles are a wireless connection The wireless connection solved a "non-problem" -- they sacrificed a reliable connection for a small amount of convenience. There is also a version of this device with a wire, that appears to be a relic from a much earlier time.

We are not sure about this, but we have seen some models of this device advertised with a high resolution video camera. If really present, this is a wise engineering decision as it makes the problem of camera postion much less concerning.

The image quality of this device, when we saw it about a year ago, was "OK". A good feature of this device is that the Synapsis company is stable and unlikely to vanish. We thought it cost too much, especially considering the much cheaper devices available with similar image quality. It seems likely to us that these are CE approved.

Vestibular First Goggles

 

Vestibular First is a start-up US company, that appears to be attempting to fill in the huge void left by the Micromedical RealEyes goggle system. It appears to be designed to be inexpensive (about $1250-1500). Unfortunately, it does does not solve the focus problem (which is critical). This device uses a pair of USB cameras. Obviously it does not allow for monocular viewing, it is bulky, and there is no method of positioning the camera. The methodology (like others) is to avoid a focussing knob and mechanical positioning by putting the cameras far away from the eye, and using software to crop the portions of the image that are not the eye. We have not yet tried this device out and cannot say right now about whether or not it is effective. We see it's main selling point is a good price compared to some of the alternatives, and also FDA approval. We are told that FDA approval has been attained. It is not CE approved. The images above were emailed by me by the developer.

Nagashima Video Frenzel Goggles (Japan)

These goggles are appear lighter in weight and less bulky than the newer designs, and share some features of the Micromedical Real-Eyes frame. We are not certain about many details, and we have never used these goggles. They have a composite output, and are about 500x500 resolution. Although the design is very old, they appear better in some ways than the newer devices which look more like VR systems. We are not sure how they deal with facial anatomy, or focus. We are not sure if these are FDA or CE approved.

Russian goggles (vestibular.ru)

 

A Russian designer of video frenzel goggles has created what appears to be a device that solves several of the problems of the others on this page.. These goggles can be purchased on ebay. They view both eyes at the same time using mirrors, they have some abilty to focus, but their resolution is low because the camera is quite far away from the eye. They are USB based. These goggles are not FDA or CE approved. We think these goggles have some good design points and are much better than most on this page. We have not seen them "live" as yet. Their biggest issue is likely low resolution as the cameras are quite far away from the eye.

Argentina goggles: Sercom Argentina

This company, Sercom, has developed goggles in Argentina, that look very much like the Vestibular First goggles. The camera is a composite type, and can be directly connected to a TV set. They also have other models as well. Prices are similar to Vestibular First. We have not tried out these goggles and do not know how well they perform. From the exterior, it is clear that they are not monocular goggles, which greatly limits their usability. It seems doubtful that these are FDA or CE approved.

Vesticam

This device is a camera that is connected to a portable android phone, at 27 fps, as well as directly to a PC or Mac using a USB cable. It is patented and ARTG (i.e. Australian) approved but not FDA approved. It can be purchased for education and research purposes right now. It states that it has a focus adjustment. I have not tried this device out, but it appears reasonable.

The Micromedical RealEyes goggle (no longer made).

The video-frenzel goggle model that we favor is the "RealEyes" monocular. Sadly, they are no longer being made. When they were made, they cost considerably more (about $2600) than optical Frenzels (typically about $500), but they were worth the price because they "had it all". The excellent Micromedical goggles were discontinued a few years before the vestibular PT's discovered goggles, and was likely a bad business decision.

Very good features of these goggles included the focussing mechanism, the ability to angle the camera, a nearly indestructible design, and composite cameras. The composite camera meant that you could just hook this camera up to a TV and you were ready to go. One could also process the composite signal with a USB converter, add a Picture-in-Picture processor, etc. More about this is found here.

Do it yourself Goggles -- two versions

It is possible to make your own Frenzel goggles, for even less of an investment. Several designs have been provided. See this page for more details.

In Conclusion:

There is space in the market for a better video Frenzel goggle. We hope that this happens soon as these devices are extremely useful.

If I have missed any video Frenzel goggle makers, please send me an email, and I would be pleased to add your device to this page.

References

• Baba, S., et al. (2004). "A comparative study on the observation of spontaneous nystagmus with Frenzel glasses and an infrared CCD camera." J Nippon Med Sch 71(1): 25-29.