The Experimental Study of N-HA/PVA-H Keratoprosthesis

Yao Xiaoming, Deng Hongwei, Qi Wei, Zhu Fengjiao, Li Ming, Nie Danyao, Yu Li

Shenzhen Eye Hospital, Shenzhen Ophthalmic Center of Ji'nan University Medical College, Shenzhen 518040, China

Purpose: To explore the biocompatibility and the biohealing characteristics of a newly design porous nanohydroxyapatite/polyvinyl alcohol hydrogel keratoprosthesis (n-HA/PVA-H KPro) with the animal experimental studies. The n-HA/PVA-H KPro was implanted to the alkali-burned corneal stroma of rabbits. This study was estimating the clinical feasibility of the n-HA/PVA-H simultaneously.

Methods: Ten New Zealand white rabbits have been used in these studies. The rabbits were randomly numbered NO.1 to NO.10. To obtain a similar clinical condition of alkali-burned corneal, the rabbits' corneas were alkali-burned by 1mol/L NaOH three months before the surgical implantation procedure.
Stage I operation: The n-HA/PVA-H KPro was inserted to the alkali-burned corneal 1/3 anterior stroma. The biocompatibility and corneal neovascularization were observed everyday after operation for 3 months.
Stage II operation: The anterior lamellar corneal tissues were removed and the central optical core of the KPro was exposed. The stability of the KPro and corneal condition were observed by slit-lamp microscope. Two of the animals were sacrificed 1 month and 2 months after operation. Then the corneas were removed for the histological studies by light microscope. The surface of the artificial corneal skirt was observed under scanning electron microscope. The remaining rabbits were investigated to estimate for the clinical outcome for three months. The anterior chamber angles were observed with the ultrasonic bio-microscope (UBM) three months after operation.

Results: NO.7 rabbit was terminated because of a failure operation. The rest of 9 n-HA/PVA-H KProes have been retained well with the parasitifer without severe complication during the experiment. The central optical core of the KPro was keeping transparence condition except NO.1 and NO.8 rabbits, The proliferous membrane appeared in front and post of the Kpro，respectively. Histological studies showed that fibroblast and neovascularization had penetrated the microporous of the nanohydroxyapatite(n-HA) skirt. The extracellular matrix deposited on surface of NHA skirt was more denser and tighter than traditional keratoprosthesis.

Conclusions This study shows the newly design n-HA/PVA-H KPros could profited the adhesion of the fibrocyte and promoted the corneal neovaslarization. It also improves the nutrient deposit and prevent the epithelial growth. The excellent compatibility and optical properties make n-HA/PVA-H KPro designed has clinical application prospect. The patent of this newly design has been achived in July 2009 in China(Patent No. ZL 2004 1 0027122.6).