As an eyeglass wearer, you may often have to deal with the nuisance of foggy lenses. You move from a warm to a cold environment, from outdoors into an air-conditioned area, or vice versa. Or sip into a hot beverage, or start cooking. Instantly, your eyeglasses fog up to obstruct your vision. Moreover, this common annoyance is becoming especially challenging now that the pandemic has made wearing masks obligatory. Having to wipe off the mask-induced mist from your eyeglasses throughout the day is a hassle. And if you operate heavy machinery, or perform as a frontline worker, clear vision is crucial. Hazy glasses can be hazardous in your job.

But why does this happen, and what is the solution? Here are the explanation and some useful tips.       

What causes fog on your eyeglasses?

Fogging is the result of phase change of matter, that is, its transition from gas to liquid. When warm air with water in its vapour state strikes a cold surface, the steam turns into liquid-state, forming condensation.

The same thing happens when the water vapour in your warm breath escaping through the top of your mask touches your lens. Or steam from hot liquids, or moisture from your sweat, lands on your eyeglasses. The water vapour, being hotter than the lens, thus loses its heat to the cold glass. It triggers the change of the vapour into its liquid phase. Minute droplets then form on your eyeglasses that scatter light rays, turning the lenses foggy. Tight-fitting frames that hamper airflow make the problem worse.

How to keep your eyeglasses from fogging up?

Avoiding every situation that leads to your eyeglass fogging up is not realistic. Fortunately, there are several straightforward techniques to avoid the annoyance and the associated risks.   

1. Treat your eyeglass lenses to an anti-fog coating: 

Regular eyeglass wearers have found several creative solutions that achieve this result.

• Wash with soapy water: Dip your spectacles in soap water, shake off the excess liquid, and allow the glasses to air-dry. A thin layer of soap sticks to the lens. It reduces the surface tension of water, which is its tendency to shrink into the least surface area, forming droplets. The soap makes the water spread out over the lens in a transparent film that allows light to pass through.
• Use shaving foam: Polish your lenses with a small blob of shaving foam. Allow it to dry and then gently wipe off the extra with a soft cloth. This method creates a layer that urges water to coat the lens as a transparent film. It lasts long and solves the issue of fogging.

The problem with such hacks is that these can erode any anti-glare, UV- blocking, or blue-light protective coatings on your prescription glasses. Therefore, it is wise to check with your optician and opt for fog-resistant eyeglasses.

Some other less-risky approaches are as follows:

2. Wear eyeglass frames that fit right

Glasses that sit away from your face allow the air to circulate freely around the lenses, minimizing condensation build-up. You can try to adjust the nose pads or the arms of our spectacles to increase the airflow around the lenses. However, on prescription glasses, especially ones with progressive lenses, this can result in vision alterations. Hence, you may want to consider buying a better-fitting frame that provides more space between your face and the glasses.

3. Keep your eyeglasses clean

Condensations easily adhere to any dirt, scratches, or smudges on your lenses. Therefore, it is essential to keep your lenses clean. Avoid leaving fingerprints on them and handle the glasses with care to avert scratches.

4. Adjust the fit of your mask

While wearing a mask, you can keep your lenses from fogging up by directing your breath away from the lenses. For this, make sure that the top of your mask sits snugly over your nose. A secure fit will prevent your breath from escaping through the mask. You can try the following:

• If your mask has ties, you can tie the top ones below your ears and the bottom strings above them. This crisscross tying will create a tighter fit.
• You can buy a mask with a nose-bridge that moulds the mask’s edge to better fit your face.
• Pull your mask high up your nose, place your glasses on top, and seal the margin.
• Tie two knots on the strings of your mask.

5. Choose your seasonal accessories with care

Avoid overdressing your head and neck in winters with excess layers. It can cause your body to overheat, leading to sweats and hot breaths, making your glasses fog. Choose breathable materials to allow airflow.

6. Buy anti-fogging sprays/ wipes

Such products can produce temporary fog-resistant eyeglasses by turning water vapour into non-scattering transparent water-films over your lenses. But you must repeat the application at short intervals for the best results.

7. Invest in anti-fog glasses

A more long-term solution is to buy eyeglasses specially designed to prevent condensation build-ups. Regardless of the reason behind the fogginess, masks, or otherwise, lenses with an anti-fog coating like Essilor Optifog UV are the most effective solutions. The anti-fog property lasts long because you can apply a specially formulated activator on either side of the lenses once a week. The coating on the lenses retains the activator, blocking fog formation. Thus if you want permanent freedom from foggy eyeglasses, ask your eye doctor about Optifog lenses.

FAQs

Why does my eye fog up my glasses?

It is not your eye but your breath that fogs up your glasses. When your warm breath reaches your lenses, the water vapour in it condenses into tiny water droplets. These drops scatter light in multiple directions, and light cannot pass through the glass. Thus, your vision becomes blurred. The same thing happens when steam or moisture-laden hot air touches your cold lenses.

How do I keep my glasses from fogging under my mask?

• Line the top of the mask with some tissue paper before wearing it.
• Ensure a tight seal of the mask’s top margin over your nose bridge by tying its strings in a crisscross fashion behind your head.
• Use a mask with a nose bridge that takes up the shape of your face.
• Wear anti-fog glasses with special fog-repellant coating.