Transitioning from wearing glasses to contact lenses offers visual freedom and convenience. Contacts eliminate frame obstructions, providing a wider field of view and making physical activities easier. This shift requires a dedicated examination and a new daily routine, not just transferring your eyeglass prescription. Understanding the differences in prescriptions and lens care requirements is the first step toward successful wear.
Why Your Contact Lens Prescription Differs from Your Glasses Prescription
A contact lens prescription is distinct from an eyeglass prescription due to the lens placement relative to your eye. Eyeglasses sit approximately 12 to 14 millimeters away from the cornea, creating the vertex distance. Contact lenses rest directly on the eye’s surface, making the vertex distance zero.
This difference alters the effective power, especially for stronger prescriptions. For powers exceeding about +/- 4.00 diopters, the eye care professional must perform an adjustment calculation called vertex compensation. For nearsightedness, the contact lens power will be slightly less minus, and for farsightedness, the power will be slightly more plus.
Beyond corrective power, the prescription must include measurements unique to the lens’s physical fit. The Base Curve (BC) defines the curvature of the back surface, which must match the curvature of your cornea. The Diameter (DIA) specifies the width of the lens, ensuring it covers the cornea for stability and comfort.
Choosing the Right Contact Lens Type
Contact lenses are divided into soft lenses and Rigid Gas Permeable (RGP) lenses, with soft lenses being the most common. Soft lenses are made from flexible, water-containing plastic polymers called hydrogels. Newer Silicone Hydrogel lenses incorporate silicone to allow more oxygen to pass through to the cornea, promoting better eye health.
RGP lenses are constructed from a firmer, durable plastic that allows oxygen to permeate. They offer sharper vision than soft lenses and are often recommended for specific vision issues, such as high or irregular astigmatism. RGP lenses require a longer initial adaptation period and are less comfortable than soft lenses.
You will also choose a specific wear schedule. Daily disposables offer the highest convenience and hygiene, as they are worn once and discarded. This eliminates the need for cleaning and storage solutions, reducing the risk of infection. Bi-weekly or monthly lenses are more cost-effective but require a strict regimen of cleaning and storage.
Specialty lenses address complex vision needs. Toric lenses correct astigmatism using multiple power curves, requiring a precise fit to prevent rotation. Multifocal or bifocal lenses contain different power zones for near, intermediate, and distance vision, providing an option for people with presbyopia, an age-related focusing difficulty.
Essential Hygiene and Handling Practices
Proper hygiene is necessary for safe contact lens wear. Always wash your hands thoroughly with soap and water, then dry them with a lint-free towel before touching your lenses. This prevents the transfer of microorganisms and debris to your eyes.
When inserting and removing lenses, always use the soft pads of your fingertips, not your fingernails, to avoid damaging the lens or scratching the eye. Establishing a consistent routine, such as always starting with the same eye, prevents mixing up lenses if your prescriptions differ.
For reusable lenses, the “rub and rinse” method is recommended, even if the solution is labeled “no-rub.” After removal, rub both sides gently with fresh solution, and then rinse thoroughly before soaking. Never use water or saliva to clean or store lenses, as tap water can harbor harmful pathogens like Acanthamoeba that cause severe eye infections.
The lens case requires diligent care, as it can quickly become a breeding ground for bacteria. After use, empty the old solution, rub the case clean with fresh solution, and allow it to air-dry upside down with the caps off. Replacing the lens case every three months is recommended to prevent bacterial biofilm buildup.
Troubleshooting Common Beginner Issues
New contact lens wearers may experience minor issues as their eyes adapt. The most frequent complaint is dryness or discomfort, especially after extended wear or in dry environments. Using rewetting drops specifically approved for contact lenses can help lubricate the eye and lens.
A common beginner mistake is inserting a lens inside-out, which immediately feels uncomfortable and results in blurry vision. Check the lens orientation by placing it on your fingertip and viewing it from the side. If the edges point straight up like a cup, it is correct; if the edges flare outward like a bowl, it is inverted.
Adaptation takes time, especially with RGP lenses, which require a longer break-in period. Contact your eye doctor immediately if you experience red flags signaling a serious issue, such as sudden blurred vision, persistent redness after removing the lenses, or severe, persistent pain.