All our swim goggles are treated at point of manufacture with an anti-fog coating. While no coating lasts forever these normally are good for upwards of one year with average use of the swim goggles.
Our original V1 goggles have been sold along with an aftermarket anti-fog treatment “ZEROFOG”. This has been used with no problems.
HOWEVER, our new style of prescription swim goggles, “V2”, has a factory anti-fog coating that is adversely affected by the application of ZEROFOG. The ZEROFOG actually dissolves part of the factory coating and gives the appearance of a heavily scratched lens.
The lenses are not actually scratched (unless an abrasive cloth or tissue was used) and the irregular marking can be removed by using “isopropyl alcohol” commonly called rubbing alcohol. Place a few drops of alcohol onto the inside of the lens & rub with your finger to dissolve all of the factory coating. Then rinse in HOT water.
Alcohol will also dissolve any factory anti-fog coating on the V2 goggles and then ZEROFOG can be used to provide anti-fogging protection.
If you have used ZEROFOG on the V2 Goggles, you will have to use alcohol & a finger scrub to remove all the factory coating then rinse with HOT WATER. You might have to let the lens soak for a while to make sure all coating on the inside of the lens is removed. Then ZEROFOG or other anti-fog treatment can be applied.
If you have cleaned the inside of any lens and it appears badly scratched it might be useful to try removing the factory coating as this scratches much more easily than does the polycarbonate lens.