Experimental 24 Hour Corneal Swelling by Extended Wear Contact Lenses

ABSTRACT

We evaluated corneal swelling induced by extended wear contact lenses(EWCLs) in New Zealand white rabbits domestically available in Korea. At first, we measured the corneal thickness prior to contact lens wearing with ultrasonic pachometer and examined the condition of the anterior segment of the eye. Then four soft EWCLs, one rigid gas permeable lens, and one disposable lens were applied on the corneas of the rabbits for 24 hours in closed eye condition achieved by transient tarsorrhapy. After 24 hours, the corneal thickness was remeasured and the condition of the external eye was reexamined to compare with the initial values. Conclusively, corneal swelling was developed after 24hour wearing of EWCLs in all rabbits. The percent corneal thickness changes decreased inthe following order; Ciba soft(Cooper Vision) 27.54%. Hyper II(International Contact Lens Lab.) 21.99%, Bescon III(International Contact Lens Lab.) 16.15%, Ciba thin(Cooper Vision) 14.22%, Optima FW(Bash and Lomb) 13.79%, Acuvue(Johnson and Johnson). The control group whitch did not wear any contact lens showed no change in the corneal thickness(p>0.05). The results of corneal swelling correlated well with the DK/L of each EWCLs. This experiment revealed that the EWCLs used widly in Korea could induce corneal swelling and so careful evaluation 0f the EWCLs wearers may be required.