menu Contact Us Dizzy Patients Health Care Providers Research BPPV DVD Tai Chi DVD Understanding Dizziness Acknowledgements Disclaimer Quoting

Frenzel goggles

Timothy C. Hain, MD Page last modified: December 13, 2011

There are two types of Frenzel goggles -- optical and video. The video are far preferable, but they cost substantially more than the optical versions.

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.

Frenzel, a German physician, 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

ENG display Video-Frenzel goggles.

In the authors 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. While some video Frenzel goggles offer the ability to see both eyes simultaneously, this capabilty is usually associated with several small images on a security style TV monitor. We do not think that the ability to see both eyes simultaneously adds much value, and the small images detract from the devices usefulness.

Such video-eye movement recording systems, called "video Frenzels", such as those sold by Micromedical Technology (Chatham IL, USA, 217-483-2122) 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 model that we favor is the "RealEyes" monocular. They cost considerably more (about $2600) than optical Frenzels (typically about $500). We do not favor systems that require a computer, and we also do not favor systems that monitor both eyes at the same time. We prefer "analog" monitors to flat-screens, as display contrast is more reliable and a very large monitor is much more attainable. Because the size and resolution of the image is critical, a "quad splitter" is not recommended. Instead, we favor a "picture in picture" processor (PIP), that puts a small dirigible image in a corner of the display. We are uncertain whether the "record to PC" feature is useful. We STRONGLY advise against models that do not have a focus knob.

The main advantage of optical Frenzels over video Frenzels are their portability and lower cost. If you go this way, we suggest that you buy your own large monitor, as well as a room camera, DVD player, and PIP processor. As of 2010, this costs roughly $1000 more. More about this is found here.

Anyway, there are six sources of the optical Frenzel glasses that I am aware of which are discussed below:

Copyright August 3, 2016 , Timothy C. Hain, M.D. All rights reserved. Last saved on August 3, 2016