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.
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.
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:
|Type||Example||Reason for ranking|
|Video, high end||MIcromedical Real eyes||Focus, positioning, no computer needed|
|Video, low end||
Russian goggles, Synaptic goggles
|No focus or positioning, computer needed. Thus, can't always see torsion.|
|Good visualization of eyes, patient not in darkness|
|No frenzels||Patients can fixate.|
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:
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 goggles (From https://www.synapsys.fr/en/diagnose)|
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.
|Internals of 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 Goggles(From) https://www.nagashima-med.com/products-lineup/frenzel-goggles/infrared-eye-movement-imaging-tv-device|
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 (From this page)|
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.
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.
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 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.
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.
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.