To investigate ethnic differences in corneal endothelial bleb formation and corneal swelling during contact lens wear
under closed-eye conditions, with the use of lenses of varying oxygen transmissibilities (Dk/L) in Asian and non-Asian subjects.
Asian and non-Asian contact-lens naive subjects were fitted with one of four different types of contact lenses at each 20-minute session. During lens wear, the eyelid was closed. Endothelial bleb formation was determined by specular microscopy or confocal microscopy immediately on eye opening. Some Asian contact-lens naive subjects were asked to wear one of two types of lenses (Dk/L values of 24 and 175) on each eye for 1 hour. Corneal swelling was determined immediately after opening of the eyes.
Asian subjects had a significantly higher degree of endothelial bleb formation than the non-Asian population for all closed eye conditions, p=0.0001. There was no significant difference in endothelial bleb formation between closed eyes with or without lenses in the non-Asian population. There was a significantly higher degree of bleb formation with low Dk/L lenses, ≤40, compared to high Dk/L lenses, ≥110, in Asian subjects, p=0.0001.
There is a significant difference between Asian and non-Asian subjects in the corneal response to stress. Under a closed eyelid only contact lenses with very high levels of Dk/L do not cause cornea stress in Asian patients.