Researchers found that plasma-enhanced chemical vapour deposition (PECVD) of polymerised 1-vinyl-2 -pyrrolidone (NVP) and poly(ethylene glycol) methacrylate (PEGMA) on orthokeratology lenses leads to a significant increase in hydrophilicity and a clear anti-adhesive effect.

Enhanced hydrophilicity and anti-fouling effect demonstrated on orthokeratology lenses coated with NVP and PEGMA via plasma-enhanced chemical vapor deposition. Source: Adobe.Stock

Plasma-enhanced chemical vapor deposition (PECVD) is a vacuum plasma treatment procedure for the deposition of thin film on a substance, which was first used on orthokeratology lenses (ortho-k lenses) in order to coat polymerized 1-vinyl-2-pyrrolidinone (NVP) and poly(ethylene glycol) methacrylate (PEGMA) on the lenses. First, the surface of ortho-k lenses was pretreated with electrons, radicals, and peroxides for 9 min, under 9 sccm Ar, 36 sccm O2, and 120 W of applied radio frequency (RF) power. NVP and PEGMA were deposited on the surface of lenses through the heating of NVP to 50°C and PEGMA to 43°C.

The chamber pressure was maintained at 300 mTorr, with 40 W of applied RF power, 12 sccm Ar, and an 8-cm treatment distance. Obviously decreased water contact angle of NVP/PEGMA-coated lenses exhibited excellent hydrophilicity, which lasted for up to 90 days, and significant lower protein adsorption was observed on NVP/PEGMA-coated lenses. Besides, the MTT assay revealed the great biocompatibility of the coated lenses. Therefore, the results showed that PECVD can be used to prepare NVP/PEGMA-coated ortho-k lenses with excellent long-lasting hydrophilicity and anti-fouling effect.