Determination of protein deposits on RGP lenses by X-ray photoelectron spectroscopy

Hideji Ichijima, Tetsuji Kawai, Kazuaki Yamamoto, Harrison D Cavanagh

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Purpose: To establish a novel and objective screening method for evaluating the cleaning efficacy of contact lens care solutions for removal of protein deposits on single rigid gas permeable (RGP) lenses. Methods: New and unworn RGP lenses containing no nitrogen atoms were incubated in a standard tear protein test solution. Protein deposition on lenses was determined by X-ray photoelectron spectroscopy (XPS) before and after standardized cleaning with commercially available care solutions (daily cleaners A, B) and a wetting/soaking solution or with 0.1 w/v% sodium dodecyl sulfate (SDS) as a control. Cleaning efficacy was calculated based on the percentage of nitrogen atoms present in the total elements of the measured XPS scan spectrum. Results: Nitrogen atoms originating from residual protein deposits on RGP lenses after cleaning were determined by XPS. The cleaning efficacy of the wetting/soaking solution was lower (74%) than that of daily cleaners A and B (95%) or SDS (96%) controls. Conclusions: XPS determination of residual protein deposits is a novel and direct evaluation method for determining the cleaning efficacy of RGP lens care solutions for single lenses.

Original languageEnglish (US)
Pages (from-to)18-20
Number of pages3
JournalCLAO Journal
Issue number1
StatePublished - Jan 1 2000

ASJC Scopus subject areas

  • Ophthalmology


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