An in vivo comparison of the kinetics of protein and lipid deposition on group II and group IV frequent-replacement contact lenses.
OBJECTIVE
To investigate the degree and rate of deposition of protein and lipid on FDA group II and group IV contact lens materials over a period of up to 28 days of wear.


METHODS
Twenty-two subjects wore a group IV lens (Acuvue) and a group II lens (Soflens 66) in a randomized, cross-over study. The lenses were randomly worn for periods between 1 and 28 days and then collected for laboratory-based deposition analysis.


RESULTS
The group II lenses revealed an increased degree of lipoidal spoilage (p < 0.0001) and the group IV lenses exhibited increased protein spoilage (p < 0.0001). Surface protein for both materials reached a maximum after 1 day and did not increase over the 4-week wearing period (p = NS). Total protein for group IV lenses reached a maximum between 1 and 7 days and then reached a plateau, with no further increase occurring (p = NS), whereas total protein accumulation on the group II lens continued to increase across all time periods (p < 0.05). Lipid deposition on the group IV lens was maximal after 1 day and increased no further (p = NS), whereas lipid deposition on the group II material monotonously increased and progressively built-up over the 4 weeks of wear (p < 0.0001).


CONCLUSIONS
The kinetics of contact lens deposition is mediated by the chemical structure of the contact lens material under consideration. Protein deposition occurs rapidly with group IV materials before reaching a maximum, whereas N-vinyl pyrrolidone-containing group II materials progressively accumulate protein and lipid deposits, with no plateau occurring.
Jones
L
L
Biomaterials Research Unit, School of Engineering and Applied Science, Aston University, Birmingham, United Kingdom. lwjones@sciborg.uwaterloo.ca
Mann
A
A
Evans
K
K
Franklin
V
V
Tighe
B
B
D000328:Adult; D001672:Biocompatible Materials / Q000737:chemistry*; D003263:Contact Lenses, Hydrophilic; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008055:Lipids / Q000032:analysis*; D008297:Male; D011109:Polymethacrylic Acids / Q000737:chemistry*; D011506:Proteins / Q000032:analysis*; D011760:Pyrrolidinones / Q000737:chemistry*; D016037:Single-Blind Method; D013056:Spectrophotometry, Ultraviolet; D013499:Surface Properties; D013997:Time Factors
D001672:Biocompatible Materials; D008055:Lipids; D011109:Polymethacrylic Acids; D011506:Proteins; D011760:Pyrrolidinones; C042670:N-vinyl-2-pyrrolidinone