Abstract
Purpose: :
Previous studies suggest that Asian, compared to non–Asian, corneal epithelium, is more susceptible to micro–trauma during contact lens wear. [Lin et al., CL & AE 2003; Lin et al., E & CL 2003S] Is this change in corneal epithelial permeability to fluorescein (Pdc) due to normal anatomical/physiological differences between Asians and non–Asians or is it due to the interaction differences during contact lens wear (CLW) between the two ethnic groups? To answer this question, we measured Pdc in non–CLW groups of Asian and Non–Asian subjects.
Methods: :
Pdc was measured using an automated scanning fluorometer on 39 Asian and 40 Non–Asian subjects with no prior history of contact lens wear. Pdc measurements were taken at a minimum of 4 hours after awakening (PM) on all subjects. 23 Asians and 24 Non–Asians returned the following morning with one eye patched prior to sleep. Morning Pdc was measured in the patched eye immediately after patch removal and within 2 hours of awakening for the unpatched eye.
Results: :
Mean ± SD PM Pdc were –2.52 + 0.31 and –2.45 + 0.28 for Asians and non–Asians, respectively (p > 0.05). Mean ± SD Pdc values immediately after eye opening after overnight eye closure were –2.42 + 0.15 and –2.56 + 0.15 for Asians and non–Asians, respectively (p > 0.05). Within 2 hours of awakening, Mean ± SD Pdc values were –2.44 + 0.12 and –2.40 + 0.12 for Asians and non–Asians, respectively (p > 0.05).
Conclusions: :
There was no fundamental difference in corneal epithelial barrier function between Asians and non–Asians. This suggests that the higher increase of corneal epithelial permeability after overnight soft CLW in Asians is a result of other parameters (e.g., vertical palpebral aperture size, presumed higher lid tension, thinner post–lens tear thickness) that lead to more disruption on the corneal epithelium.
Keywords: cornea: epithelium • cornea: clinical science • contact lens