on Wednesday, June 27, 2012
Many contact lens wearers find that they occasionally fall asleep with their contact lenses still on and want to know if that is okay. Other patients find that sleeping in contacts is desirable and want to know for how long they can do so. Sleeping in contacts without any negative effects to the eye is dependent on several factors. Some of these factors are the lens material, lens thickness, the prescription, and the length of time the eye is closed while sleeping in contacts.
When the eye is closed, the cornea receives oxygen from the blood vessels in the underside of the lids. When sleeping in contacts, the lens material must have enough oxygen permeability to allow oxygen to diffuse through the lens to reach the cornea. Currently, the highest oxygen permeability is found in lenses made from a silicone hydrogel material such as CooperVision’s Biofinity lenses. If contact lenses are not made from a silicone hydrogel material, the thinner a lens is and the higher the water content a lens has, the higher the oxygen permeability will be. However, the oxygen permeability is no where nearly as great as in a silicone hydrogel lens. The more nearsighted (myopic) a person is, the thinner the center of the contact lens. The more farsighted (hyperopic) a person is, the thicker the center of the lens. People who need a correction for astigmatism or are wearing multifocal contacts will also have slightly thicker lenses. The material, design, thickness and prescription all influence the amount of oxygen passing through a contact lens.
Sleeping in contacts for overnight wear requires a lens that has received extended wear approval from the FDA. Just because a lens has been approved for extended wear does not guarantee that a person sleeping in contacts will be able to do so successfully. That is dependent not just on the amount of oxygen reaching the cornea, but on the composition of the tears, the amount of deposits on the lens, the amount of lens dehydration and tear exchange beneath the lens.
When sleeping in contacts for a short period of time, just remove the lenses upon awakening. It may be necessary to instill some contact lens approved rewetting drops to loosen the lens prior to removal. Problems are rare when sleeping in contacts for a short period of time, like napping. If you plan on sleeping in contacts overnight, you may want to use rewetting drops after you wake up to help improve comfort and vision. Sleeping in contacts overnight does have a higher risk factor for corneal problems. If you are sleeping in contacts and develop pain, redness, blurred vision, etc. make sure to contact your eye doctor immediately.