Abstract
Purpose: :
To evaluate biocompatibility of microporic poly β-hydroxyethyl methacrylate (PHEMA) and polymethyl methacrylate (PMMA) in the cornea of a rabbit xerophthalmia model.
Methods: :
1) The rabbit xerophthalmia model was constructed by ablating the lacrimal gland, 3rd eyelid and Harder’s gland of the right eye of New Zealand rabbits and cauterizing the bulbar conjunctiva at the superior and inferior fornix with 50% trichloroacetic acid (TCA). 2) PHEMA was a circular thin film of 5 mm in diameter and 0.1 mm in thickness with a hole diameter of 50~100 µm. PMMA was a circular thin film of 5 mm in diameter, 0.1 mm in thickness with a hole diameter of 200 µm. 3) Surgical procedures: An arch incision was made between 10 and 1 o’clock of the cornea at about 2 mm of the corneal lumbus to a 1/2 to 2/3 depth of the corneal thickness to form a 6 mm circular corneal lamellar pocket. PHEMA and PMMA were implanted to the pocket respectively. 4) Clinical manifestations of cornea were observed and recorded at postoperative 15 days, 1 and 2 months under the slit lamp. Histological change of the cornea was observed by HE stain.
Results: :
Corneal edema and turbidity of the surgical eye alleviated gradually within 15 days after operation, and angiogenesis was seen around the suture. One month after operation, the cornea became clear, and newborn vessels grew downward from the corneal incision in the form of a curtain or brush with homogenous density. Histological examination showed synthesis of small numbers of collagenous fibers and growth of small vessels in micropores around the thin film. Slit lamp examination 2 months after operation showed that the number and density of newborn corneal vessels decreased significantly. Histological examination showed that there were slender spindle-like corneal matrix cells and synthetic collagenous fibers at the conjunction of the cornea and the implanted material, and the number of newborn small vessels was also increased, which grew steadily to the center of the thin film.
Conclusions: :
Under the xerophthalmic condition, both PHEMA and PMMA had good biocompatibility in the corneal tissue.
Keywords: cornea: tears/tear film/dry eye