If you spend a lot of time in swimming pools, know this: Chlorinated water can really hurt your eyes. For one thing: Chlorine doesn’t kill all the bacteria in the water, which means, you’re going to be exposed to germs that can cause eye diseases like pink eye. And the number of germs in the water depends on how recently the chlorine was added, how much was added and how often the pool is used. Meaning the busier the pool, the bigger your risk of eye problems.

Also, swimming in chemically treated water can temporarily affect your vision. Optometrist Dr. Glenda Secor says when our face is underwater; the sterile film of tears that helps protect our corneas from bacterial infections is replaced by pool water. That means all the contaminants – including chlorine, dust, and bacteria – can get up close and personal with our eyeballs. Chlorine also dehydrates the cornea, which can lead to temporarily distorted vision. In most people, the symptoms will go away after a few minutes. But for older people, it can take several hours for your eyes to feel normal. So use lubricating drops to flush out the chlorinated water, and replenish your tears.

And be extra careful if you wear contact lenses. Dr. Secor says after a swim, flush out your eyes with sterile solution before you put your contacts back in. Because if your lenses trap contaminated pool water against your cornea – or absorb the water – it can cause painful corneal ulcers, or even blindness. And that night, even if you’re allowed to wear your contact lenses while you sleep, take them out at bedtime. That’ll give your tears a chance to wash away any germs or contaminants.