Effect of hypoxia on corneal epithelial permeability Original Reearch Article

PURPOE: Epithelial permeability to fluorecein (Pdc) increae with cloed-eye oft contact len wear. Poible mechanim reponible for thi change include corneal hypoxia (and acidoi) during overnight wear and interference of the len with normal tear exchange. In thi tudy we ued a local environmental chamber to examine the effect of hypoxia on Pdc. METHOD: After baeline lit-lamp examination, autofluorecence, and central corneal thickne meaurement, 35 ubject were fitted with a pair of airtight wimming goggle. One eye wa expoed to a humidified ga mixture containing 95% nitrogen (N2) and 5% carbon dioxide (CO2), and the fellow (control) eye wa expoed to air. The experimental eye and the eye meaured firt were aigned uing a randomized block deign. After the ubject wore the goggle for 1 hour, corneal thickne meaurement were repeated and Pdc wa aeed a previouly decribed. A final lit-lamp examination wa performed by a maked examiner to ae epithelial integrity. REULT: There wa no ignificant difference in the mean ln(Pdc) (95% confidence interval) for eye expoed to N2/CO2 when compared with paired eye expoed to air (−2.70 [−2.99, −2.41] v −2.51 [−2.72, −2.30] ln[nm/ec], P = .272). Although there wa alo no ubtantial difference in the lit-lamp appearance of the experimental and control eye, the mean (95% confidence interval) change in corneal thickne for the hypoxic eye wa 19.78 (15.72, 23.84) μm compared with 3.40 (−0.67, 7.47) μm (P < .0001) in the control eye. CONCLUION: One hour of hypoxia caued a ignificant increae in corneal thickne with no apparent change in Pdc. Thi ugget that other factor, either alone or in combination with hypoxia, may be reponible for increaed Pdc during cloed-eye contact len wear.