The impact of foggy goggles on sensation and perception

I've been an avid skier for over 25 years -- but I didn't start using goggles until very recently. Under the overcast Washington State skies, they didn't seem to be necessary. But now that I live in North Carolina, skiing is usually done under sunny skies on artificial snow; goggles are a must. As a person who also wears glasses, however, the experience can be frustrating -- any time I stop for more than a few seconds, my goggles, glasses, or both will usually fog up -- the goggles rely on airflow to keep from getting foggy. In this situation, I'm left with two choices: proceed with impaired vision and hope I don't run into anything, or begin a lengthy defogging process.

For soldiers, construction workers, and others who rely on protective eyewear, the fogging problem can be even more significant. If lenses fog up, they can be tempted to remove the goggles and risk an eye-threatening injury. While anti-fog coating can reduce fogging, no studies have examined how well goggles perform in real-world circumstances. Furthermore, fogging can occur in many different conditions, and no study has attempted to replicate the most common conditions of eyewear fogging.

Jacquelyn M. Crebolder and Rodger B. Sloan devised a simple test to measure the effectiveness of different types of eyewear by simulating the most common conditions of lens fogging: coming into a warm environment out of the cold, or generating body heat through exertion while outside. Crebolder and Sloan tested Canadian soldiers under both conditions. Take a look at this graph of perceived lens fogginess.

Participants rated the fogginess of lenses on a scale of 1 to 5, where 1 was perfectly clear and 5 was completely opaque. The blue line represents the fogginess of lenses that were chilled and then worn at room temperature: after just a few minutes, these lenses were perfectly clear. However, if participants rode exercise bikes in a chilled room, after about 5 minutes, the lenses gradually became foggier, and continued to increase in fogginess over a long period of time.

During both conditions, the participants were required to perform a simple vision test: they looked at a six-by-six grid of dark circles. The task was to indicate whether one of the circles was lighter than the others (half the time a light circle was present, and half the time it was absent). Half the participants wore goggles without anti-fog coating and half wore coated goggles. Here are the results:

When participants were not exercising but wore cold goggles in a warm room, their reaction time while the goggles were foggy was significantly faster wearing coated goggles than wearing uncoated goggles. However, while exercising in a cold room, reaction times when the goggles were foggy were not significantly different, whether or not goggles had anti-fog coating (however, the coating did keep goggles fog-free for about 10 minutes).

When accuracy was measured, however, the results were different:

Anti-fog coating improved accuracy in both conditions.

Crebolder and Sloan suggest that anti-fog coatings on goggles should be systematically tested under these realistic conditions to determine which coatings are most effective. What I'd like to know is whether Canadian military anti-fog coating is available for my eyeglasses.

Crebolder, J.M., & Sloan, R.B. (2004). Determining the effects of eyewear fogging on visual task performance. Applied Ergonomics, 35, 371-381.