At present, clinical treatment of myopia mainly includes spectacles, laser surgery, orthokeratology, and other methods. Orthokeratology uses specially designed orthokeratology lenses to reshape the cornea and rapidly improve uncorrected visual acuity. Compared with refractive surgery, orthokeratology has the advantages of being non‑surgical and reversible. Current studies have confirmed that orthokeratology lenses (OK lenses) have shown positive effects in slowing the progression of myopia and correcting daytime vision in adolescents, and are increasingly widely used in clinical practice.

However, as the wearing time increases, problems may occur on the lens surface, such as reduced hydrophilicity, oxygen permeability and antifouling performance, protein deposition, bacterial proliferation, and decreased wearing comfort. Therefore, proper lens care is essential to ensure a safe, comfortable and effective wearing experience.

Incomplete or inadequate care can lead to reduced hydrophilicity and protein deposits on the lenses, which further impair wearing comfort, causing foreign body sensation, dry eyes, and even corneal inflammation due to bacterial growth, endangering ocular health. Regular deep cleaning and care are thus necessary for both the lenses and the wearers.

Surface modification is the most direct and effective way to improve the surface properties of biomaterials. Compared with other methods, plasma cleaning features a simple process, easy operation, controllable parameters, low equipment cost, and no pollution. It does not affect the bulk properties of the substrate and provides strong sterilization effects, making it one of the effective methods for biomaterial surface modification.

Plasma Cleaning

When energy is applied to a gaseous substance, some of its atoms become ionized. This state is known as the fourth state of matter, distinct from solid, liquid and gas, also called the plasma state. Plasma is an electrically neutral substance composed of charged ions and particles, which can react with materials and transfer energy.

Plasma cleaning is a dry cleaning technology that requires no water and involves only gas‑solid interactions. During the reaction, energetic particles bombard the substrate surface, effectively modifying the surface free energy, wettability and other properties. The plasma cleaning process acts only on the material surface, at a depth ranging from several to hundreds of nanometers, and therefore does not alter the bulk properties of the material. Gases used for modification are typically oxygen, argon and similar gases, so no harmful emissions are produced.

Simply put, plasma acts like a super cleaner that gently cleans the lens surface. Organic contaminants are quickly removed and thoroughly pumped away by the built‑in vacuum pump, achieving molecular‑level cleaning and leaving the lens extremely clean. Meanwhile, plasma reacts with organic substances on the lens surface to produce carbon dioxide and water. This not only cleans the lens but also improves its hydrophilicity, making lens wear more comfortable

Main Functions of Plasma Cleaning

Improved Hydrophilicity – Enhanced Wearing Comfort

Orthokeratology lenses have low water content and absorb little moisture. After prolonged use, polymers can accumulate on both inner and outer surfaces. Professional plasma cleaning equipment uses a large number of energetic particles to bombard and restructure the polymers on the lens surface, generating more polar groups and reducing the wetting angle of the lens material. This alleviates foreign body sensation and greatly improves initial adaptation during lens wear.

Enhanced Antifouling Performance

Plasma cleaning can form functional groups on the lens surface, making it more difficult for bacteria, charged proteins, conjunctival sac secretions and other contaminants to adhere. The lenses become easier to clean and maintain.

Molecular‑Level Cleaning – Higher Cleanliness

Inside the plasma cleaner, gas plasma in the cleaning chamber gently cleans the lens surface and alters its molecular structure, achieving ultra‑cleaning of organic contaminants. Contaminants are quickly removed and exhausted by the vacuum pump, achieving molecular‑level cleanliness. This improves surface smoothness and enhances visual quality during and after lens wear.

Auxiliary Sterilization – Improved Safety and Health

Studies and experiments have verified that low‑temperature plasma provides rapid bactericidal and disinfection effects. It reduces the adhesion of bacteria and residual mucus from the conjunctival sac, improving the safety of lens wear.