Contact lenses are thin medical devices placed directly on the surface of the eye, primarily used to correct vision or change the eye’s cosmetic appearance. These lenses are engineered to sit precisely on the cornea for clear vision and proper eye health. The practice of layering contacts, often called “piggybacking,” involves wearing two separate lenses on the same eye. This article addresses the safety and physical implications of wearing multiple lenses.
The Medical Stance on Layering
Eye care professionals strongly advise against layering contact lenses. This practice is considered an improper and unsafe use of a medical device. Contact lenses are designed and fitted to the unique curvature of a single eye. Introducing a second lens fundamentally alters this precise fit, compromising the intended function and safety.
Common Reasons for Considering Layering
The motivation behind layering is often a desire to combine vision correction with a cosmetic effect. A common scenario involves wearing a clear prescription lens underneath a non-prescription colored or novelty lens. This is sometimes seen as a less expensive alternative to purchasing custom-made prescription colored contacts. Other users may consider layering to adjust a minor vision issue or correct a slightly incorrect prescription, such as stacking a weak power lens to fine-tune visual acuity. Some also attempt this practice to address minor discomfort or fit issues with their primary lens.
Physical Consequences of Wearing Multiple Lenses
Layering contacts impedes the flow of oxygen to the cornea, a condition known as hypoxia. The cornea lacks blood vessels and must absorb oxygen directly from the air and tears to stay healthy. Stacking a second lens, especially a thicker, colored one, amplifies the barrier effect, starving the underlying corneal tissue.
Chronic oxygen deprivation can trigger corneal neovascularization, a response where abnormal blood vessels grow into the clear cornea. This vessel growth interferes with corneal transparency and can permanently compromise vision. Hypoxia also leads to corneal swelling and increased susceptibility to infections, such as microbial keratitis.
The presence of two lenses disrupts the necessary movement of the lens on the eye, which is essential for tear exchange and debris clearance. This poor fit and resulting friction can lead to corneal abrasions or ulcers. The space between the layered lenses becomes a breeding ground for bacteria and a site for rapid buildup of proteins and debris, which clouds vision and increases the risk of a severe eye infection.
Safe Alternatives to Layering
Individuals seeking both vision correction and a change in eye color should opt for prescription colored contact lenses. These devices combine the necessary power correction with the desired color tint in a single, medically approved lens. They are custom-fitted to ensure proper oxygen flow and movement on the eye.
Aesthetic Needs
For those who wish to use non-prescription colored lenses for aesthetic reasons, a safe alternative is to wear them in combination with prescription eyeglasses. This method provides the cosmetic effect while correcting vision without layering lenses on the cornea.
Fit and Prescription Issues
If the underlying issue is a poor fit or incorrect prescription, consulting an eye care professional for an updated examination is the correct course of action. They can prescribe a different brand, material, or type of lens, such as a specialty or hybrid lens, designed for complex vision needs.