Abstract
Purpose: :
Determine metabolic effects of closed and open eye lid conditions in the rabbit with/without high Dk silicone hydrogel contact lenses (lotrafilcon A [lotA]).
Methods: :
Six rabbit eyes wore lotA lenses under closed eye lids, six closed eye lids had no lenses, six open eyes wore lotA lenses and six open eyes had no lenses. Rabbits were anesthetized, lenses placed on appropriate eyes, and one eyelid of each rabbit sutured per study design. Following awakening, the rabbits were in the study for six hours after which they were euthanized and tissues harvested. The open eye was sampled first; 0.25 mL. of aqueous humor was aspirated with 30 gauge needle; corneas were excised with corneal scissors inside the limbal junction. Each cornea tapped dry of surface fluid, weighed and extracted in 0.5 mL of 8% perchloric acid at 4ºC for 20 hours. Aqueous humor samples were analyzed for glucose (n=6) and lactate (n=6) and corneal extract for lactate (n=6). The T-test was used to determine statistical significance.
Results: :
Significant differences (p<0.05) were observed for corneal lactate between open no lens vs closed no lens, between open lens vs closed lens, and between open no lens vs open lens. No significant difference in lactate was observed between closed no lens and closed lens. Significant differences were observed for aqueous lactate between open lens and closed lens and between open no lens vs open lens. The open eye lotA lens-wearing eyes had significantly lower lactate levels in the cornea (3.301±0.252 µmol/gm wet wt) and in the aqueous humor (5.369±0.666 mM) compared to open eyes not wearing lenses (cornea: 3.806±0.465 µmol/gm wet wt and aqueous: 6.580±0.504 mM).
Conclusions: :
As expected the open eyes w/wo lenses had higher aqueous glucose than comparable closed eyes and open eyes had lower lactate than closed eyes w/wo lenses. However, in this study open eyes fit with lotA lenses had significantly less lactate in the cornea and the aqueous humor compared to the eyes with no lens.
Keywords: contact lens • cornea: basic science • metabolism