You've probably often heard, "You shouldn't wear contact lenses for more than eight hours," but modern people often wear contact lenses for over ten hours due to study or work demands. With so many types of contact lenses available, like daily disposables, monthly lenses, colored lenses, and enlargement lenses, does the wear time remain the same for all?

Oxygen permeability affects wear time – Colored lenses with dye should not be worn for long

According to an article published by the Ministry of Health and Welfare's Food and Drug Administration, wearing contact lenses for more than ten hours a day can reduce oxygen levels reaching the eyes. While this might not cause acute corneal inflammation immediately, prolonged wear over time may lead to severe corneal hypoxia and dehydration, causing blood vessels to grow into the cornea. This can result in corneal edema and scarring, which may permanently affect vision and, in severe cases, lead to blindness.

Dr. Hou Yu-Chih, an ophthalmologist at Cathay General Hospital, explains that wearing contact lenses for eight to ten hours is generally fine as long as the lenses have high oxygen permeability and the wearer's eyes are healthy. Silicone hydrogel lenses typically offer about five times more oxygen permeability than hydrogel lenses, so Dr. Hou recommends choosing silicone hydrogel lenses or lenses with an oxygen permeability rate of 70 to 80 for long wear times. However, wearing them overnight should still be avoided, as this increases the risk of corneal damage and infection.

For those who favor colored or enlargement lenses, Dr. Hou notes that these products often contain dyes, which reduce oxygen permeability and can trigger allergic reactions. He advises against wearing them for long periods, especially for those with allergies.

Wearing daily disposable lenses repeatedly may harm your eyes

In the past, monthly and yearly contact lenses were the most common, and these could be used for a month or a year with proper cleaning. However, Dr. Hou emphasizes that daily disposable lenses must be discarded after one day of use. Reusing daily lenses reduces their overall oxygen permeability and material quality, making them unsuitable for further wear. Repeated use can lead to dry eyes, redness, corneal hypoxia, edema, and blood vessel growth, ultimately damaging your eyes.

Improper wear can damage the cornea

Every time you put in or remove contact lenses, there is a chance of accidentally scratching your cornea with the lens or your fingernail. In severe cases, this can lead to symptoms like redness, stinging, light sensitivity, and blurry vision. Generally, corneal scratches heal within a few days, but you should stop wearing contact lenses during that time and follow your ophthalmologist's prescribed treatment, such as using antibiotic eye drops to prevent infection and help the cornea heal faster.

What if your contact lenses get stuck after sleeping with them on?

Many contact lens wearers have experienced wearing their lenses for too long or accidentally sleeping with them on, only to find the lenses stuck to their eyes. This happens because long wear allows protein deposits to accumulate on the lenses, leading to corneal hypoxia and edema, while drying out the surface of the eye. This combination causes the lenses to stick to the corneal surface. Dr. Hou recommends using artificial tears to moisten the eyes, resting to allow natural tear production, and then gently removing the lenses.

Six situations when you should avoid wearing contact lenses:

1. When you have an eye infection, cold, or during an eye inflammation
2. In dry or poor working environments (e.g., air-conditioned rooms or long flights)
3. During pregnancy
4. While swimming or showering
5. While sleeping
6. While barbecuing or eating hot pot

Your eyes are precious, and you should never compromise their health for convenience. Handle your contact lenses carefully to protect your vision.