A study of the effect of X-ray irradiation on the structure of Narafilcon A biopolymer soft contact lenses

Abstract

Background. The effects of external factors such as X-ray irradiation on the structure and physical properties of contact lenses are very important for both the patients using contact lenses and medical personnel. Objectives. The aim of the study was to investigate the effect of X-rays on the structure of Narafilcon A silicone-hydrogel contact lenses. Material and methods. In order to study the structural changes caused by X-rays in Narafilcon A polymer contact lenses, the following spectroscopy methods were used: positron annihilation lifetime spectroscopy (PALS), Fourier transform middle infrared spectroscopy (FTIR) and Raman spectroscopy (RS). Irradiation of the investigated sample was carried out using an Elekta Synergy accelerator. The contact lenses were irradiated with the following total doses of X-rays: 0.05 Gy, 0.5 Gy, 0.8 Gy, and 1.0 Gy. Results. The PALS measurements showed that X-ray irradiation caused slight changes in the size of the free volume and the fractional free volume in the structure of the polymer contact lenses examined. However, the FTIR and RS measurements showed that X-rays did not break the monomer bonds in the polymeric structure of the sample. Conclusions. The changes revealed by the PALS method may be related to possible displacement of monomer chains, resulting in changes in the dimensions and numbers of free volumes. The finding that X-ray radiation does not affect or damage polymer bonds can in the future contribute to the use of X-ray and gamma radiation to sterilize contact lenses.

Positron Annihilation Lifetime Spectroscopy as a Special Technique for the Solid-State Characterization of Pharmaceutical Excipients, Drug Delivery Systems, and Medical Devices—A Systematic Review

“…An increased total irradiation dose decreased the free volume size and slightly increased the number of free volumes. The X-rays did not affect the microstructure in a negative way and did not cleave monomer bonds [ 115 ]. Calcium deposits were investigated in PHEMA soft contact lenses (Soflens and Super Soft).…”

Using X-ray Technology to Sterilize Medical Devices

“…Structural studies on polymer materials used in medicine have developed rapidly in recent years, e.g., for the production of contact lenses. In another study Filipecka et al [20], of was to examine changes in the polymer structure of Narafilcon A soft siliconehydrogel contact lenses (a very popular type of contact lens) due to exposure to X-ray irradiation. The finding showed that X-ray radiation did not affect or damage polymer bonds and can in the future contribute to the use of X-ray and γ-radiation to sterilize contact lenses.…”