All contact lenses, without exception, are classified as prescription medical devices in the United States and require a valid prescription from a licensed eye care professional. Contact lenses are thin, dome-shaped devices that sit directly on the cornea. They must be properly fitted to ensure eye health, regardless of whether they correct vision or change eye color. Improper use or fitting carries a risk of causing serious harm to the eye.
The Mandatory Requirement: Medical Necessity and Legal Status
Contact lenses are regulated as medical devices by the U.S. Food and Drug Administration (FDA) due to their direct contact with the sensitive surface of the eye. Most lenses fall under the Class II or Class III medical device categories, requiring strict compliance and proof of safety before they can be legally marketed. This classification applies to all types of lenses, including those that correct vision and those that are purely decorative.
A prescription is necessary because contact lenses are not a one-size-fits-all product. An improperly fitted lens can cause serious complications, such as corneal abrasions or a tight lens syndrome that starves the cornea of oxygen. These issues can lead to painful eye infections, corneal ulcers, neovascularization, and in rare cases, permanent vision loss.
Federal law mandates that all contact lenses be dispensed only upon a valid prescription. The Federal Trade Commission (FTC) enforces the Fairness to Contact Lens Consumers Act (FTCLCA), which governs the sale and verification process. This law requires prescribers to release the prescription to the patient and ensures all sales are based on an unexpired and verified prescription. Selling lenses without a valid prescription violates FTC regulations and is considered misbranding of a medical device.
Obtaining and Using Your Contact Lens Prescription
Obtaining a contact lens prescription begins with a comprehensive eye examination to assess overall eye health and visual acuity. This is followed by a separate, specialized contact lens fitting. A glasses prescription is not interchangeable because eyeglasses sit away from the eye, while contact lenses sit directly on the cornea, requiring different power calculations and physical measurements.
The fitting involves specific measurements that determine the lens parameters for comfort and proper function. The prescription will include the Base Curve (BC), which measures the curvature of the back of the lens to match the cornea’s shape. It also specifies the Diameter (DIA), which is the width of the lens.
The prescription also lists the Power or Sphere (PWR/SPH), measured in diopters, to correct nearsightedness or farsightedness. For patients with astigmatism, additional values for Cylinder (CYL) and Axis (AX) are included to indicate the degree and angle of correction needed.
A typical contact lens prescription is valid for a specified duration, usually one year. After this period, a new eye exam and fitting are required to check for any changes in eye health or vision. When purchasing lenses, the retailer must receive a copy of the prescription or verify the details with the prescriber.
Regulatory Status of Decorative and Cosmetic Lenses
A common misconception is that non-corrective lenses, such as colored or costume lenses, can be purchased without professional oversight. The FDA regulates all contact lenses, including those with zero power (plano lenses) intended for cosmetic purposes, as Class II medical devices. This regulation protects the public from the risk of injury caused by improper fit, even without vision correction.
Decorative lenses still require a proper eye examination and a prescription to ensure they fit the eye’s unique curvature and size. Lenses purchased from unauthorized sources, such as novelty shops or online vendors that do not require verification, are often unapproved by the FDA and may be illegally manufactured. Using these unapproved and improperly fitted lenses significantly increases the risk of developing corneal infections, abrasions, and severe eye injuries.