Obtaining contact lenses without a valid, current prescription from a licensed eye care professional is illegal and medically unsafe. Contact lenses are classified as regulated medical devices by the U.S. Food and Drug Administration (FDA) due to their direct interaction with the eye. This classification applies to all types of lenses, including those for vision correction and purely decorative or colored contacts. The requirement for a prescription is a fundamental safeguard designed to protect eye health and prevent serious injury.
Why a Prescription is Legally Mandated
Contact lenses are legally regulated as medical devices under the Federal Food, Drug, and Cosmetic Act. Most types are classified as Class II or Class III devices, meaning they must meet strict compliance and safety standards before being sold. The legal requirement for a prescription is enforced by the Federal Trade Commission (FTC) through the Fairness to Contact Lens Consumers Act (FCLCA) and the subsequent Contact Lens Rule.
This law mandates that eye care providers must give patients a copy of their contact lens prescription immediately after a fitting. The FCLCA also governs the sales process, requiring all sellers—whether online or in a brick-and-mortar store—to dispense lenses only in accordance with a valid prescription. Sellers must either receive the prescription directly from the patient or verify its details with the prescriber before the sale is completed.
The Essential Role of the Eye Exam
The eye examination for contact lenses is a specialized medical procedure that goes far beyond simply determining the vision correction power needed for distance or reading. A standard prescription for eyeglasses is insufficient because it does not contain the physical specifications required for a lens that rests directly on the eye’s delicate surface. The fitting process involves a precise assessment of both ocular health and the physical dimensions of the eye.
A crucial measurement taken is the base curve (BC), which defines the curvature of the back surface of the contact lens and must closely match the shape of the cornea. This ensures the lens rests correctly on the eye without being too tight or too loose. A diameter measurement is also taken to confirm the correct overall size of the lens. If the base curve or diameter is incorrect, the lens can cause discomfort, blurry vision, and serious physical damage to the cornea.
The eye doctor assesses the health of the eye, checking factors like tear film quality and the presence of underlying conditions to determine if the patient is a suitable candidate for contact lens wear. An improperly fitted lens can restrict oxygen flow to the cornea, a condition known as corneal hypoxia. This restriction can lead to swelling and compromise the eye’s ability to resist infection. The professional eye exam ensures the physical lens specifications are appropriate for the individual eye, preventing issues even if the vision power is accurate.
Health Dangers of Misusing Contacts
Wearing contact lenses without professional guidance or a proper fit significantly increases the risk of severe, vision-threatening complications. The most serious risk is microbial keratitis, an infection of the cornea caused by bacteria, fungi, or Acanthamoeba. This infection is the leading cause of contact lens-related blindness and is often linked to poor hygiene, such as showering or sleeping in lenses.
An ill-fitting lens, even with the correct power, can rub against the cornea and create tiny scratches or tears, known as corneal abrasions. These abrasions provide an entry point for infectious organisms. The lack of professional instruction on cleaning and wearing schedules amplifies the chances of contamination. Improperly cleaned lens cases or reusing old solution introduces a high risk of infection.
Another common issue is giant papillary conjunctivitis (GPC), an allergic reaction where small bumps form on the inner surface of the eyelid due to deposits on the lens. This often results from extended or improper wear. These complications are amplified when lenses are worn for too long or are not replaced on schedule, which frequently occurs when purchasing unverified products. Microbial keratitis can result in permanent loss of visual acuity and severe damage.