Deposition of lipid, protein, and secretory phospholipase A2 on hydrophilic contact lenses.
OBJECTIVE
Recent studies have shown that low tear phospholipid levels are associated with tear film instability in hydrophilic contact lens wearers. The concentration of secretory phospholipase A2 (sPLA2), the enzyme that hydrolyzes phospholipids, in tears is known to exceed the levels found in serum by four orders of magnitude. This study was performed to determine the levels of sPLA2 from the deposition on two different frequent-replacement contact lens materials.


METHODS
Polymacon and etafilcon A contact lenses worn for 2 weeks by 16 experienced contact lens wearers were used for the analysis. Total lipids were determined by the sulfo-phospho-vanillin reaction. Phospholipids in lipid extracts were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Total protein was measured by bicinchoninic acid analysis. Double-antibody sandwich enzyme-linked immunosorbent assay was used to determine sPLA2 concentrations.


RESULTS
Total lipid deposition was found to be greater in the polymacon group (66.3+/-16.3 microg/lens) than in the etafilcon A group, although phospholipids were not detected in either group. The etafilcon A group had greater deposition of protein (3.7+/-0.7 mg/lens) than the polymacon group had. The etafilcon A group deposited statistically significantly more group IIa sPLA2 (1.1+/-0.3 microg/lens) than the polymacon group (0.07+/-0.04 microg/lens) did (P<0.001).


CONCLUSIONS
There was a significant difference in the lipid and protein deposition profiles in the two lenses tested. A significant amount of sPLA2 in the deposition on contact lenses may play a role in tear film instability in hydrophilic contact lens wearers.
Mochizuki
Hiroshi
H
Division for Vision Research, National Institute of Sensory Organs, National Tokyo Medical Center, Tokyo, Japan.
Yamada
Masakazu
M
Hatou
Shin
S
Kawashima
Motoko
M
Hata
Seiichiro
S
D000328:Adult; D003263:Contact Lenses, Hydrophilic; D004797:Enzyme-Linked Immunosorbent Assay; D005136:Eye Proteins / Q000032:analysis*; D005260:Female; D006801:Humans; D020100:Hydrogels; D008055:Lipids / Q000009:adverse effects*; D008297:Male; D008689:Methacrylates / Q000737:chemistry*; D054467:Phospholipases A2 / Q000032:analysis*; D011102:Polyhydroxyethyl Methacrylate / Q000031:analogs & derivatives* / Q000737:chemistry; D013666:Tears / Q000378:metabolism
D005136:Eye Proteins; D020100:Hydrogels; D008055:Lipids; D008689:Methacrylates; C114176:etafilcon; C000257:polyhydroxyethyl methacrylate hydrogels; D011102:Polyhydroxyethyl Methacrylate; D054467:Phospholipases A2