Have you ever wondered what sleeping in your contact lenses does to your eyes? Is leaving your contact lenses in your eyes for 15 or more hours per day safe? Contact lenses are a great alternative to wearing glasses all the time for people who are nearsighted, farsighted and/or who have astigmatism. However, they come with risk. Proper cleaning and care needs to be taken when wearing contact lenses.
Why do my lenses feel uncomfortable and I am not able to wear them more than a few hours per day?
Contact lens discomfort can be due to many problems. For example, the contacts could be causing your eyes to dry out. Sometimes using an artificial tear (non-preservative drop) can help with re-wetting the eye and improving contact lens comfort. Alternatively, your eye could be having an allergic reaction to dust/pollen in the environment causing discomfort. Sometimes switching to a daily contact lens can help with this or by using allergy eye drops. Your eye may also be forming protein deposits on the contact lens causing discomfort. Usually cleaning your contacts with a hydrogen peroxide solution can help with this. Sometimes switching between contact lens solution brands can also cause ocular allergies. It is best to use one brand and stay with it.
Why is my vision more blurry in my contact lenses and clearer in my glasses?
This can be due to various reasons but generally speaking, myopes (people who are nearsighted and have blurry vision far away) see better in contacts than in glasses. People who are hyperopic (farsighted and have difficulty reading up close) can see better in glasses then in contacts. Patients with astigmatism sometimes face more challenges in contacts because their exact prescription is often not available in a contact lens, so the closest prescription available is what is corrected for.
For example, take the prescription: -2.00-1.50X73. The cylinder portion of the astigmatism is -1.50, contacts however do not come in a -1.50 so the eye doctor would likely put you in an astigmatism lens correcting -1.25D. Secondly, the axis which the astigmatism sits on is 73. Astigmatism contacts don’t come in 73 for the axis for astigmatism…only 70 or 80…so the doctor would likely put you in an axis of 70 as 73 is closer when rounded to 70 then it is to 80.
Why do I see glare and halos at night while driving in my contacts more so then in my glasses?
At night, the black part of our eyes (the pupil) gets larger or dilates to allow more light in. Due to the large pupil, spherical aberration can occur around the pupil which can cause glare/halos around lights. This isn’t as severe with glasses however, as most glasses come with an anti-reflective coating which blocks some of the glare/halos.
What are the risks involved with over wearing my contact lenses?
Contact lens over wear can cause your eyes to become red, watery, burn and you may start to see rainbows and halos around lights (swelling of your cornea). More importantly however, contact lens over wear usually results in not enough oxygen reaching the cornea. This can be caused by sleeping in contacts (this is a big no-no), not replacing contact lenses as directed, or wearing contact lenses for too many hours per day. The real issue with not enough oxygen reaching the cornea (front of the eye) is that prolonged decrease of oxygen to the cornea can lead to neovascularization. This is where new blood vessels grow on the front of the eye to bring more oxygen to the eye. Even if contact lens wear is reduced, once these vessels form they are always there (they may just not be filled with blood – in this case they are called ghost vessels). Ultimately this can cause irregularity to the cornea and degrade vision. On a more severe scale, this could even lead to the need for a corneal transplant.
Contact lens over wear can also lead to a condition called Giant Papillary Conjunctivitis (GPC)
GPC is an ocular allergy your eye is having. This allergy can sometimes be to the contact lenses themselves or to the solution you are using but most commonly the allergy occurs when protein deposits form on the contacts. GPC causes big bumps to form under the eyelids (usually upper eyelids). Most people report they can “feel the lens” as they blink their eyes. It can also cause the eyes to become red, watery and perhaps even have a ropey textured discharge. The best way to deal with GPC is to discontinue contact lens wear for a period of time (as directed by your Optometrist). Your Optometrist will likely also prescribe anti-inflammatory or anti-allergy drops to speed recovery and ease your symptoms. Once resolved, it is a good idea to switch to daily contact lenses as protein deposits do not have a chance to form on these lenses, or switch to a different lens material altogether.
Perhaps the most serious condition associated with contact lens over wear is the occurrence of a corneal ulcer. A corneal ulcer is basically an open sore on the front surface of the eye (the cornea). It is usually white/grey in colour and may be too small to see with the naked eye. Corneal ulcers can cause the eye to become red, watery, or feel very painful (especially when looking at bright lights), and sometimes even produce a thick discharge. Corneal ulcers are usually cured with prescription eye drops. Without treatment, corneal ulcers can lead to a loss of vision and even blindness. The good news is that corneal ulcers can be prevented! It is very important to remember to never sleep in your contacts. Never wash your contacts with saliva, tap water, or anything other than contact lens solution. Wash your hands before putting contacts in the eyes and remember to clean the contact lens case!
To find out what type of contact lens is best for you (daily/biweekly/monthly), please speak with one of our highly trained Optometrists.