Influence of dynamic contact of hard contact lens materials on corneal epithelial cells examined by rose bengal staining.
OBJECTIVE
To establish a method for evaluation of less irritating contact lens materials by dynamic contact with cornea, we examined epithelial and endothelial cell injury to the porcine cornea caused by rotatory rubbing with four kinds of hard contact lenses (HCL).


METHODS
The HCLs used were (1) polymethylmethacrylate (PMMA) HCL, (2) gas-permeable HCL composed of a graft co-polymer of dextran derivative and methylmethacrylate (MMA) (Suncon Mild II(TM), 12 Dk), (3) gas-permeable HCL composed of a graft co-polymer of dextran derivative, a monomer containing silicone, a monomer containing fluorine and MMA (New Dx HCL-136, 32 Dk), and (4) gas-permeable HCL composed of a monomer containing silicone, a monomer containing fluorine and MMA(RGPL-A, 216 Dk). Using a specially designed apparatus, we produced a standardized injury to the epithelium or endothelium of porcine corneas by holding the HCL against the corneal surface while rotating the lens rapidly.


RESULTS
After rotatory rubbing of the HCL on the epithelium, the degree of rose bengal staining of the epithelial cells, indicating degeneration of the cells and mucin detachment, were significantly different among these HCLs (New Dx HCL-136 < Suncon Mild II(TM), PPMA < RGPL-A), and the cell injury rates of the endothelium were also significantly different among them (Suncon Mild II(TM) < New Dx HCL-136, PMMA < RGPL-A). The water-wettability of HCLs was not directly correlated with cell injury rates on epithelial and endothelial cells.


CONCLUSIONS
Both the New Dx HCL-136 and Suncon Mild II(TM), which have a common composition of graft co-polymer of dextran derivative, are less irritating to the epithelium and to the endothelium. Also a very few patients complaints regarding Suncon Mild II(TM) wearing in individuals with dry eyes have been reported. Therefore, we would expect that the New Dx HCL-136 should be satisfactory for wear by individuals with dry eyes.
Iguchi
I
I
Division of Research and Development, Sun Contact Lens Co., Ltd., 475 Sasaya-cho, Fuyacho-Ebisugawa, Nakagyo-ku, Kyoto 604, Japan.
Kamiyama
K
K
Imamichi
M
M
Ohashi
T
T
He
J
J
Wang
X
X
Imanishi
J
J
D000818:Animals; D003261:Contact Lenses / Q000009:adverse effects*; D003315:Cornea / Q000166:cytology; D065306:Corneal Injuries; D004728:Endothelium, Corneal / Q000166:cytology / Q000293:injuries; D004848:Epithelium / Q000293:injuries; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D007638:Keratoconjunctivitis Sicca / Q000150:complications; D008422:Materials Testing; D012395:Rose Bengal; D012449:Safety; D013314:Stress, Mechanical; D013552:Swine; D014867:Water
D005456:Fluorescent Dyes; D014867:Water; D012395:Rose Bengal