Abstract
Purpose: :
Determine corneal metabolism of rabbit corneas following six hours of either lotrafilcon A [lotA] lens wear or no lens wear. The Dk of lotrafilcon A material is 140 barrer.
Methods: :
The study design controlled for tissue sampling order and consisted of four groups of rabbits (n=3 per group): 1) rabbits wearing lotA lenses in both eyes, 2) rabbits with open eyes wearing no contact lenses, 3) rabbits wearing a lotA lens OD and no lens OS, and 4) rabbits with no lens OD and a lotA lens OS. Following the six hour study period, the rabbits were euthanized and tissues harvested. The OD was sampled first; 0.20 mL. of aqueous humor was aspirated with 30 gauge needle; corneas were excised with corneal scissors inside the limbal junction. Each cornea was tapped dry of surface fluid, weighed and extracted in 0.5 mL of 8% perchloric acid at 4ºC for 20 hours. Each aqueous humor sample was analyzed for glucose (n=3) and lactate (n=3) and corneal extract for lactate (n=3). ANOVA analysis was used.
Results: :
Contact lens wear was a significant main effect (p=0.000254) only for corneal lactate with reduced levels observed with lotrafilcon A lens wear compared to no lens. The sampling order was a significant main effect or interaction in all three assays. The effect of sampling the first eye compared to the second eye was about a 5% increase in the aqueous glucose and about a 5% decrease in aqueous lactate independent of lens wear. The corneal lactate decrease was about 28% with lens wear and about 7% with no lens for the first eye compared to the second eye.
Keywords: contact lens • metabolism • hypoxia