Gas Permeable (GP) lenses offer wearers a distinct combination of sharp vision and long-term durability. These lenses are made from a firm, oxygen-transmitting plastic that allows the cornea to “breathe,” reducing the risk of issues associated with older hard lenses. The rigid material maintains a stable shape on the eye, which is effective for correcting conditions like astigmatism. GP lenses require a specialized regimen of care solutions that differ significantly from those used for common soft lenses. Selecting the correct solution is paramount for maintaining lens clarity, comfort, and eye health. This guide will clarify the differences in GP lens care and help you choose the best maintenance system.
Why GP Lens Solutions Are Unique
GP lenses are fundamentally different from soft contact lenses. Soft lenses are flexible, water-containing hydrogels. In contrast, GP lenses are rigid, do not absorb water, and are composed of durable plastics like fluoro-silicone acrylate. This material difference dictates the specialized chemical components required for cleaning.
The surface of a GP lens is naturally hydrophobic, or water-repelling, making it susceptible to the adhesion of lipids and oils from the tear film. These greasy deposits compromise vision and comfort, demanding surfactant-based cleaners that specifically break down and emulsify these oily residues. While soft lenses tend to attract and bind proteins, GP lenses require a different chemical focus to address their primary deposit challenge.
GP lens solutions must also contain conditioning agents, specialized polymers designed to enhance the surface’s wettability. This process changes the lens surface at a molecular level, bringing hydrophilic elements to the surface to attract and maintain a stable layer of tear fluid. Without this step, the rigid, hydrophobic lens would feel dry and uncomfortable. Standard soft lens solutions lack these specialized surfactants and conditioning agents, making them inadequate for GP lens materials.
Multipurpose Systems Versus Two-Step Care
GP lens maintenance is organized into two primary formats: Multipurpose Systems (MPS) and Two-Step Care. MPS combine the functions of cleaning, disinfecting, and conditioning into a single bottle, offering maximum convenience and speed.
The trade-off for this simplicity is that the all-in-one formulation may not be as aggressive at removing stubborn deposits compared to dedicated daily cleaners. Users of MPS may require adjunct products, such as a weekly enzymatic cleaner, to prevent the buildup of proteins and lipids. The chemical agents in MPS must perform all functions simultaneously, which can sometimes result in a compromise between effective cleaning and optimal conditioning.
Two-step care systems separate the cleaning and conditioning functions into two distinct solutions. The first step involves a daily cleaner, often a highly concentrated surfactant, that is rubbed onto the lens to physically and chemically scrub off deposits. The second step is a separate conditioning or soaking solution, which is used for disinfection and to thoroughly re-wet the lens surface overnight.
This process generally provides the most thorough cleaning and maximum hygiene, as each chemical agent performs a single, specialized function. The drawback is the increased time commitment and higher cost due to purchasing two separate products. Hydrogen peroxide systems offer superior microbial kill rates but require a special case and a neutralization period, adding complexity.
Selecting the Right Solution and Handling Tips
Choosing the optimal GP solution involves considering the specific lens type, individual sensitivities, and lifestyle factors. For instance, large-diameter scleral lenses often require solutions with a lower viscosity for insertion. Conversely, standard corneal GP lenses benefit most from highly viscous conditioning solutions that maximize wetting and cushion the lens on the eye.
Individual sensitivities to solution preservatives, such as thimerosal or ethylenediaminetetraacetic acid (EDTA), can also narrow the selection. Patients experiencing irritation or allergic reactions may need to switch to a preservative-free system, such as a hydrogen peroxide solution. Consulting with an eye care professional is the most reliable way to select a system that matches the lens material and the wearer’s unique tear film chemistry.
Regardless of the system chosen, proper physical handling is indispensable for preventing infection and maintaining lens integrity. The routine must always begin with thorough handwashing and drying before touching the lenses. The physical “rub” step is non-negotiable for effective cleaning; this involves applying the daily cleaner to the lens and gently rubbing it with a finger pad for 10 to 30 seconds.
Following the rub, the lens must be thoroughly rinsed with a sterile saline solution to remove all loosened debris and residual cleaner before soaking. Lens cases should be emptied, rinsed with sterile solution, and allowed to air dry once the lenses are inserted in the morning. A new lens case should be used every month or with every new bottle of solution to mitigate the risk of microbial contamination. It is imperative to avoid the use of tap water for rinsing lenses or cases, as it can harbor a microorganism called Acanthamoeba, which can cause a serious eye infection.