Wearing contact lenses overnight 

Wearing contact lenses on a continuous basis without removal can be very convenient but the risk of serious eye infections with overnight wear is higher than with daily wear lenses. For example, an international survey conducted in 39 countries between 2006 and 2010 showed that the risk for severe keratitis in extended wear contact lens wearers was about 20 cases per 10,000 vs. four cases per 10,000 in daily wear lenses¹.

Sleeping in contact lenses overnight increases the risk of infection by about four times, irrespective of lens type. You should carefully discuss the benefits and risks of this option with your eyecare practitioner before proceeding. Only lenses that are specifically designed and approved for overnight (extended or continuous) wear should be worn during sleep, and then only on the advice of your eyecare practitioner.

Conventional soft lenses have prevented enough oxygen passing through to the eyes to be worn safely overnight. The new generation of silicone hydrogel lenses have much improved oxygen transmission that provides health benefits to the eye and some are approved for up to 30 days of continuous wear. However, some eyes are not suitable for this type of lens and even if you are, regular checks of the health of the eye are essential. The lenses are usually fitted as daily wear lenses and if the eyes show no sign of ill effects, overnight wear is commenced.

Rigid gas permeable (RGP) lenses are also used for overnight wear in some circumstances. Orthokeratology or ortho-K lenses (also known as corneal re-shaping or overnight vision correction) are RGP lenses designed to alter the shape of the cornea (the transparent front part of the eye). These lenses are worn nightly or alternate nights and removed in the morning. The incidence and prevalence of eye infections with these lenses is not known. It is also not known whether the risk of infection is greater for children than adults.

The success of any contact lens is also dependent on appropriate use by the wearer and it is, therefore, very important to adhere to the wearing times and replacement schedule recommended by your practitioner. All contact lens wearers should pay attention to the comfort of their lenses, the appearance of their eyes and the quality of their vision. If you experience any problems such as redness, pain or blurred vision, you should remove your lenses immediately and consult your eyecare practitioner at once.

As with all types of contact lenses, if you use continuous wear lenses you should have an up-to-date pair of spectacles for when you need to remove the lenses, such as if the eyes are irritated or if you feel unwell. It is now recognised that swimming, water sports and hot-tub use while wearing contact lenses can be associated with complications and should be avoided, unless wearing tight-fitting goggles. If lenses are worn for showering, the eyes should be kept firmly closed. For more details on wearing contact lenses overnight visit your eyecare practitioner. 

Reference

1. Efron N, Morgan PB, Woods, CA, the International Contact Lens Prescribing Survey Consortium. International survey of contact lens prescribing for extended wear. Optom Vis Sci. 2012;89(2):122-129.