| Objective To investigate and assess the efficacy of photodynamic therapy (PDT) with verteporfin (Visudyne; Novartis AG, Basel, Switzerland) for treatment of corneal neovascularization (CoNV) in a rabbit eye model and interaction of mannitol with verteporfin-PDT.Methods New Zealand rabbits were randomly devided into 4 groups. Group I was anegative control group. Corneal neovascularization was induced in rabbits by placing an intrastromal silk suture near the limbus in the rest 3 groups. Group II and group III received PDT in which verteporfin was administered by intravenous injection at a dose of 1.5 mg/kg. And 20% mannitol was administered by intravenous injection at a dose of 4.0g/kg two times in grouap II. Group IV was a positive control group. The change of CoNV was observed with slit lamp microscope and areas of CoNV were then recorded after PDT. To assess PDT-induced toxicity of the anterior segment, corneal and iris/ciliary body histology and immumohistochemitry S-ABC method, which was used to measure the expression of vascular endothelial growth factor( VEGF), were then evaluated after PDT.Results On day 3, week 1 and week 2 after PDT, the mean percentages of CoNV areas of group II and III were both smaller than group IV(P<0.01). There was no significant difference between group II and III (P>0.05). Corneal histology disclosed that vessel walls of CoNV were destroyed and thrombus was formed. The expression of VEGF in group II and III obviously increased compared to group I (P<0.01), while decreased compared to group IV (P<0.01). No significant difference was found between group II and III (P>0.05).Conclusion These results provide evidence that PDT can produce significant regression of neovascular corneal vessels with no observable toxicity to the anterior segments. Mannitol as a kind of free radical scavenge of hydroxide radica can not degrade the efficacy of PDT with verteporfin for treatment of CoNV. There was no evident interaction between vertporfin and mannitol possibly.
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