Atomic force microscopy analysis of the effect of plasma treatment on gas permeable contact lens surface topography. Issue 3 (June 2019)

• Record Type: Journal Article
• Authors: Gill, Felicity R.; Purslow, Christine; Murphy, Paul J.
• Is Part Of: Contact lens & anterior eye. Volume 42:Issue 3(2019)
• Page Start: 265
• Page End: 272
• Publication Date: 2019-06
• Subjects: Gas permeable contact lenses -- Plasma-treatment -- Surface roughness -- Comfort; Anterior segment (Eye) -- Periodicals; Contact lenses -- Periodicals; Segment antérieur (Œil) -- Périodiques; Lentilles de contact -- Périodiques; 617.752305
• DOI: 10.1016/j.clae.2019.02.010
• Languages: English
• ISSNs: 1367-0484

Abstract

Highlights: Plasma-surface treatment reduces roughness of unworn gas permeable contact lenses. Benefit of plasma treatment continues for at least 3 months of daily wear. No relationship was found between surface roughness and wear comfort. A sample preparation protocol was developed to produce repeatable results. Abstract: Purpose: Using atomic force microscopy (AFM) to investigate anterior surface topography (AST) in worn and unworn, plasma surface-treated (PST) and untreated (UT) gas permeable (GP) lenses, and influence of surface topography on in vivo comfort. Methods: GP lens AST evaluated with AFM in tapping mode, using an uncoated, 40 nm symmetric tip (sampling frequency: 300 kHz), at five randomised locations, over a 100μm 2 area, to produce mean average roughness (Ra) and root mean square (RMS) values for each sample. Four unworn lenses (two PST, two UT) were examined (Quasar/Boston EO material). Twenty worn lenses (ten PST, ten UT) of same design and material as unworn lenses collected after 3 months lens wear. General wearing comfort reported by visual analogue scale (VAS) at 3 months visit. For sample preparation, two worn UT GP lenses were divided into four segments; each segment underwent a different lens rinse and drying method. Results: Unworn: UT lenses had significantly higher mean RMS and Ra values compared to PST (Mann-Whitney, p < 0.05). Worn: UT Median RMS values were significantly higher than PST (Mann-Whitney, p < 0.05). Comfort: no correlation found between general comfort and RMS or Ra scores. Sample preparation: Method 4 (purified, distilled water rinse/nitrogen gas dry) produced optimum median RMS and Ra values. Conclusions: Unworn PST GP lenses had lower Ra and RMS values compared with unworn UT GP lenses. After 3 months wear, PST lenses had smoother surface topographies than UT lenses. No relationship was found between surface topography and lens wear comfort. Sample preparation protocol directly impacts AFM results.