Contact lenses are regulated medical devices, and prescriptions are brand-specific. You cannot switch brands without authorization, even if you find a lens with the same power. Safely and legally changing to a different brand requires a professional refitting to ensure the health and safety of your eyes.
Why Prescriptions Are Brand-Specific
Contact lenses are classified and regulated as medical devices by the U.S. Food and Drug Administration (FDA). This classification means they are subject to strict compliance requirements for safety, sterility, and effectiveness. The prescription itself is a medical order, not just a measurement of visual acuity, which is why it must include the specific brand name approved by your eye care professional (ECP).
When your ECP issues a prescription, they are guaranteeing that the specific device listed has been properly fitted and evaluated on your eye. This process ensures that the lens parameters are appropriate for your unique corneal shape and eye health needs. The legal requirement for the prescription to specify a single brand prevents retailers from substituting what they consider a “similar” lens, protecting you from receiving an unapproved or ill-fitting product.
Key Differences Between Contact Lens Brands
One brand cannot simply be interchanged with another because contact lenses are not a standardized commodity. Each manufacturer uses unique physical parameters, materials, and designs that affect how the lens interacts with the eye. The physical fit is determined by the Base Curve (BC) and Diameter (DIA).
The Base Curve measures the depth of the lens’s curvature and must align closely with the curvature of your cornea for a comfortable and stable fit. The Diameter is the width of the lens, which must be correct to ensure the lens covers the cornea completely and centers properly. Slight variations in these measurements between brands can lead to a lens that is too tight, restricting tear exchange and oxygen flow, or too loose, causing discomfort and blurry vision.
Material composition is another significant difference, with lenses made from either traditional hydrogel or modern silicone hydrogel materials. Silicone hydrogel lenses are designed to allow significantly more oxygen to pass through to the cornea, often measured by the Dk/t value (oxygen transmissibility). This material difference is important for long-term eye health. Many brands also incorporate proprietary designs, such as specific edge designs or built-in moisture agents, which contribute to lens comfort and vary significantly between manufacturers.
The Necessary Steps for Switching Brands
If you wish to switch contact lens brands, perhaps to try a newer material or find a more affordable option, the first step is to schedule an appointment with your eye care professional (ECP). Your ECP must evaluate your eyes and the proposed new lens brand before any change can be made safely.
During this visit, the ECP will conduct a new fitting exam, which involves placing a trial lens of the new brand on your eye. They will use a slit lamp, a specialized microscope, to assess how the new lens sits on your cornea, checking for proper coverage, movement, and centering. This step confirms that the new brand’s specific Base Curve and Diameter are compatible with your individual eye shape.
If the initial fit is successful, your ECP will provide a limited supply of trial lenses and establish a trial wear period, which often lasts a week or more. This evaluation period ensures the lens maintains comfort and stability throughout a typical wearing schedule and that your eye responds well to the new material. Only after a successful trial and a follow-up check will the ECP issue a new prescription, which will then specify the newly approved brand.