Frenzel goggles
Timothy C. Hain, MD•Page last modified: February 27, 2021
There are two types of Frenzel goggles -- optical and video. The content on this page discusses optical frenzels. The video frenzel goggles are far preferable, but they cost substantially more than the optical versions (Baba, 2004). See this page for the various vendors of video frenzel goggles.
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Conventional optical Frenzel goggles. |
Frenzel goggles are extremely useful in evaluation of patients with vestibular disorders. In essence, 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.
Hermann Frenzel's a German physician(Gejrot, 1994) , should not be confused with Augustin-Jean Fresnel, a French physicist. Fresnel is known for his work with optics, and his name is associated with a type of magnifying lens. Fresnel lenses are used in Frenzel's goggles, in the GN-otometrics design (see below).
Video Frenzels are much better than optical Frenzels
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Video-Frenzel goggles. |
In the authors medical practice in Chicago Illinois, we use video Frenzels. A single 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. 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. The superiority was pointed out by Baba et al (Baba, 2004).
Anyway, there are six sources of the optical Frenzel glasses that I am aware of which are discussed below:
- Baxter (cat # Au5050)
- ICS Medical
- Nagashima
- Bausch and Lomb (same as Baxter)
- Russian.ru goggles
- US Neurologicals (Blessing goggles)
- "takeaway" Frenzel glasses or "M" glasses
- Do it yourself
Most people use the Baxter or Bausch and Lomb glasses (which are the same device as Baxter).
Baxter Frenzel's Goggles
Baxter (cat # Au5050). Baxter often doesn't even seem to know that they sell these things so use the catalog #. Their goggles are actually made in Germany, and are lightweight and sturdy. The bulbs are expensive, about $20, and are the same ones used by Bausch and Lomb, but they don't blow out that frequently. One disadvantage is that you must purchase a power supply to go with them. They work well with a 4-volt supply. Too much and they get hot and the bulbs blow. Too little and you can't see. The bulbs blowing thing is a safety issue as glass shards can be produced. So, we do not recommend using anything but a fixed voltage 4-volt supply. These glasses are not UL approved.
I got mine from the V. Mueller Division (800-323-9088). Another contact # is 708-948-3756. The price in 1996 was $477 for the glasses, but Bausch and Lomb sells them for $100 less (see below). These goggles need a 4 volt power supply. Bome sells an inexpensive one that can be modified to produce 4 volts. Bome's number is 716-436-6584. Bausch and Lomb also sells a power supply.
These goggles I believe are remarketed German goggles.
ICS Frenzel's Goggles
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ICS's Frenzel's goggles have a different design than the Baxter goggles Personally, I prefer the Baxter goggles, but ICS's goggles aren't bad. They are made of plastic rather than composite like the Baxter and Nagashima brand goggles, and their lighting is a bit dim compared to either. Perhaps they could be brighter if one used a higher voltage supply. I don't know. They are priced similarly to the Baxter/Bausch and Lomb goggles.
ICS formerly was located in 2227 Hammond Drive, in Schaumberg, Illinois, 60173. 708-397-2150. ICS was purchased by Natus
Nagashima Frenzel's Goggles
The Nagashima Frenzel's goggles are the best optical goggles on the market (excepting the video system), but they are somewhat expensive (>$1200 last priced). They are nicer than the others because of their bright lighting, wide field of view, and relative comfort (for the patient). In my opinion, they are really not worth $1200 -- maybe $600, but if you have lots of money to spend, hey, why not go for the best. On the other hand, if you have lots of money to spend, it might be a better idea to get a video system. I am told (but am not entirely sure) that the Nagashima goggles are the only ones that are UL approved. This may be important if you are planning to use them in a hospital. If you don't have to move the goggles around from room to room, just get a video system - -don't waste your money on these.
Bausch and Lomb -- Frenzel goggles
Bausch and Lomb sells the same goggles as does Baxter.The part number is n0785. Prices as of 2003 for the goggle is 386.00. The B&L recommended power supply (S1910A) is 136.00.This power supply produces between 0 and 6 volts. In our opinion, it is safer (less blown bulbs) to use a power supply that cannot provide more than 4 volts. Phone: 1-800-338-2020. US neurologicals also sells Frenzel goggles (price $378, in 2006). Their part # is 701. Bome sells an inexpensive power supply that can be modified to produce 4 volts. Bome's number is 716-436-6584.
Blessing goggles
I have no personal experience with these goggles, but they appear to be an improved design of the Frenzel goggles.
According to the web page marketing these devices, these goggles have a shielded bulb, and several useful accessories. It appears to me that the lens is smaller than is desirable. I prefer the Nagashima size lens. Bigger is better, for Frenzels anyway.
As of 2006, model 721 was being sold for $445 by US neurologicals. It is usually a good idea to have extra bulbs and a provision for power. Bome sells an inexpensive one that can be modified to produce 4 volts. Bome's number is 716-436-6584.
vestibular.ru goggles
These optical goggles are made by vestibular.ru, and they originate in Russia. They can be purchased from vestibular.ru, which is in Russia.. These are reasonable goggles, with a few design differences. The illumination is with LEDs. The device is powered with a battery in the front, just under the power switch. They do not require a power supply and have no danger of being burnt out, but the battery has to be changed periodically.
There are several variants of "Frenzel" glasses, (quotes intended), that are simply spectacles.
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| Frenzel spectacles of Dhonde and Khadilkar (2020). |
One example is shown above -- these are simply 20 Diopter lenses mounted in conventional glases. A similar implementation is that of Strupp et al, (2014) called "M-glasses". While better than nothing, we think the enclosed devices above are all superior.
Do it yourself Frenzel goggles
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.
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.
- Dhonde, P. and S. Khadilkar (2020). "Frenzel glasses: an affordable alternative." Pract Neurol 20(6): 504.
- Gejrot, T. (1994). "[Hermann Frenzel and the lighted eyeglasses. He introduced a new way to measure vertigo]." Lakartidningen 91(38): 3395-3396.
- Strupp, M., et al. (2014). "The takeaway Frenzel goggles: a Fresnel-based device." Neurology 83(14): 1241-1245.