Contact lenses can be a blessing in terms of convenience and even aesthetic purposes. While they may seem small and harmless, your contacts require specific care and hygiene routines to avoid a range of problems starting with mild irritation and ending with vision-threatening conditions.

Your eyes are one of the most delicate and sensitive parts of your body after all. Here are five common mistakes you should avoid when using contact lenses:

1. Do not go swimming while wearing them

Wearing your contacts while swimming can irritate your eyes at best. In one of the worst-case scenarios, it may lead to an eye infection which can eventually lead to the development of a corneal ulcer. This can threaten your vision and even cause blindness, requiring a cornea transplant in some cases.

This risk is not just limited to swimming pools either.

"There is a risk of eye infection from bacteria in swimming pool water, hot tubs, lakes and the ocean," states the Food and Drug Administration (FDA). It is also recommended that lenses are removed before taking a shower.

2. Do not compromise on storage and cleaning 

Never use anything besides your contact lens disinfecting solution to clean your lenses whenever you remove them. That means no saliva and definitely, no water should be used. Ensure that the contacts are stored in the case with the contact lens solution, and don't forget to change the case every three months at the least. 

Also, avoid the practice of topping off i.e. adding fresh solution to the used solution in your case. Even if it appears clean, the used solution may contain bacteria which will come into direct contact with your eyes and cause a possible infection. 

3. Do not fall asleep while wearing them

Sleeping while wearing your contacts can lead to oxygen deprivation. "It's like having a plastic bag over your head when you sleep," said Dr. Rebecca Taylor, an ophthalmologist in private practice in Nashville, Tennessee. "It's not ideal for oxygen exchange."

Studies have suggested that even occasional overnight use of contacts can significantly increase the risk of corneal inflammation. If you accidentally fall asleep, Dr. Beeran Meghpara, an eye surgeon at Wills Eye Hospital in Philadelphia recommends removing the lenses as soon as you wake up and wearing glasses to allow your eyes to breathe.

4. Do not put them in after wearing makeup 

For those who wear products such as eyeliner and mascara, remember to put your lenses in before applying makeup and taking them out before removing makeup. This will avoid the possibility of trapping makeup in the lenses. 

In terms of types, waterproof and oil-based makeup are not recommended for contact wearers. There is a risk that the makeup may bind itself to the lenses. And since oil-based products are required for removing waterproof makeup, both types may ultimately cause blurring of vision.

5. Do not wear them when you are sick

Lenses should not be worn if you are suffering from a cold or flu. This particularly applies to sicknesses that affect the eyes by causing redness or puffiness. 

The reason is that your immune system is weakened when you are sick and this can increase the chances of an eye infection, explained Dr. Weslie Hamada, associate director of Professional Affairs at Johnson & Johnson Vision Care, Inc.