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Contact lens induced corneal acidosis
1Morton D. Sarver Center for Corneal and Contact Lens Research, University of California, Berkeley 94720, USA.
Purpose:
Changes in pH in the corneal epithelium, stroma, endothelium and aqueous humor following contact lens wear were evaluated.
Methods:
Intracellular pH, stromal pH, and aqueous humor pH were measured either in vivo or in vitro in humans and in rabbits using pH-sensitive fluorescent dyes. Fluorescence was measured before and during lens wear using a slit lamp fluorimeter (in vivo experiments) or a microscope fluorimeter (in vitro experiments).
Results:
The pH of corneal epithelium, stoma epithelium and aqueous humor decreased significantly with lenses up to Dk/L = 100. Hypoxia had large effects on the corneal epithelium and stroma, but had no effect on the endothelium or aqueous. Conversely, carbon dioxide accumulation caused significant acidosis in all compartments measured.
Conclusions:
Corneal acidosis during contact lens wear is significant under a variety of wearing conditions and, thus, must be considered when evaluating the morphological or functional changes that occur following long-term contact lens wear.