Contact lenses offer a popular and convenient method for vision correction, but they require strict adherence to wear and care rules to protect eye health. A common concern is whether sleeping in contact lenses could lead to severe, sight-threatening conditions like glaucoma. Glaucoma is a group of eye diseases that cause progressive damage to the optic nerve, which transmits visual information from the eye to the brain. This article addresses the specific risks associated with contact lens misuse and clarifies the connection—or lack thereof—to glaucoma development.
How Glaucoma Develops
Glaucoma is characterized by damage to the optic nerve, typically resulting from elevated intraocular pressure (IOP) inside the eye. The eye produces a fluid called aqueous humor, which circulates to maintain its shape and nourish tissues. This fluid must drain out at the same rate it is produced, exiting through the trabecular meshwork.
If the drainage angle or the meshwork becomes blocked, the fluid accumulates, causing the IOP to rise. This excessive pressure stresses the delicate nerve fibers of the optic nerve. Over time, these nerve fibers die off, creating blind spots that usually start in the peripheral vision and can eventually lead to irreversible blindness.
Is There a Direct Link to Glaucoma?
Sleeping in contact lenses is not a direct cause of primary open-angle or angle-closure glaucoma. The primary drivers of glaucoma are mechanical and vascular factors, such as faulty fluid drainage or a vulnerable optic nerve structure. These factors are linked to genetics, age, and existing medical conditions like diabetes or high blood pressure, not contact lens use.
The mechanism of harm from sleeping in contact lenses involves oxygen deprivation and microbial contamination, which are entirely separate from the internal pressure regulation issues that define glaucoma. Contact lenses do not initiate the optic nerve damage characteristic of the disease. Therefore, sleeping in lenses does not create the biological conditions necessary to cause this specific eye disease.
Common Severe Infections from Contact Misuse
The danger of sleeping in contact lenses is the significantly increased risk of severe corneal infections. When the eye is closed, the contact lens restricts the flow of oxygen to the cornea, causing corneal hypoxia. This oxygen deprivation causes the cornea to swell and compromises its natural defenses, making it vulnerable to invading microorganisms.
The risk of developing a serious infection, known as microbial keratitis, is increased by six to eight times with overnight wear. The lens can harbor bacteria, fungi, or parasites, which become trapped between the lens and the vulnerable corneal surface. One particularly dangerous organism is Acanthamoeba, a free-living amoeba often found in tap water, which causes Acanthamoeba keratitis. This infection is difficult to treat and frequently results in permanent vision loss or requires a corneal transplant.
Any infection or inflammation of the cornea, or a corneal ulcer, can lead to painful symptoms and long-term scarring, which permanently impairs vision. Even a short nap with lenses in raises the risk of irritation and discomfort, as the lens dries out and creates friction. The combination of reduced oxygen, lack of tear circulation, and trapped pathogens creates a high-risk environment for these sight-threatening conditions.
Guidelines for Safe Contact Lens Wear
To minimize the risk of eye complications, the fundamental rule is to never sleep in contact lenses unless they are specific extended-wear lenses prescribed by an eye care professional. Even with approved extended-wear lenses, the recommended wearing schedule must be strictly followed.
Proper hygiene is crucial and involves several steps:
- Always wash hands with soap and water before handling lenses, and dry them with a clean, lint-free towel.
- The contact lens case should be cleaned daily with fresh solution, never water, and replaced completely at least every three months.
- Fresh lens solution must be used every time lenses are stored; never simply “top off” old solution.
- Contact lenses should never be exposed to any water, including during swimming, showering, or using tap water for rinsing.