REPORTED STORY:During a recent holiday to South-East Asia I used shampoo for cleaning my mask to prevent it from fogging up during the dive. I have used shampoo before (e.g. in the Red Sea and Baltic Sea) without problems; but on this day, I used shampoo supplied by the dive boat.
Regrettably, the shampoo was a strong concentrate and I did not completely rinse out my mask. During the dive, I felt only mild eye-soreness. After ascending, I took the mask off and that is when the irritation got stronger and very uncomfortable, so I wiped my eyes to clear the irritant away but the situation only got worse. Back on shore, I learned there was no doctor on the island and by now my left eye was stinging so bad that I had to take an emergency boat trip to the hospital on a larger island nearby.
Later, when I returned home, I visited my local doctor and was relieved to hear that no further treatment is going to be needed.
COMMENT:This diver was lucky that his eyesight recovered fully. Nonetheless, this was a painful and frightening experience; it cut short his diving and cost hundreds of dollars for transport and treatment.
Let's briefly recap mask cleaning. When a mask is new, or when it has been in storage for a while, fumes may have settled on the inside of the lens and toothpaste is a suitable gentle abrasive that can be used to scour off this residue. After cleaning the inside of the lens, make sure all the toothpaste is removed. Next, before diving, we want to smear a fine coating of detergent on the inside of the lens to stop micro-droplets of water forming on the glass. These micro-droplets are what causes mask fogging but they will not stick to detergent. Non-irritant commercial anti-fogging agents can be purchased from many dive centers but we have a naturally occurring detergent in our saliva therefore many divers prefer to spit in their mask, then wipe the spit over the inside of the lens before swilling out any excess. It goes without saying, this is yet another good reason for owning your own mask. Whichever method you choose, remember to use clean hands to spread the detergent (smears of sunscreen, for example, will cause it to fog up). Lastly, while in theory other types of detergent might prevent fogging such as shampoo, as this diver has shown, not all shampoos are non-irritant and therefore it is still best practice to use either a commercial anti-fogging product or good old spit.
~ Peter Buzzacott, MPH, PhD