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First Author: A.Abdel-Salam EGYPT
Co Author(s): A. Hassan D. Ghoneim A. El-Dib S. Abdelkawi
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To evaluate the effect of photodynamic therapy utilizing benzoporphyrin derivative (verteporfin) and diode laser in the treatment of experimental corneal neovascularization.
The study was done on 33 New Zealand rabbits, conducted at the National Institute of Laser Enhanced Science, Cairo University. Corneal neovascularization was induced in 30 rabbits, by a three-interrupted 7.0 silk sutures at midstromal depth approximately 1 mm from the limbus. Three rabbits served as control.
Fifteen rabbits with corneal neovascularization were left without treatment, while 15 rabbits were projected to photodynamic therapy (PDT) by intravenous injection with Verteporfin at a dose of 1.5 mg /Kg. Diode laser (660 nm) was applied 15minutes later for 5 minutes with a power of 50 mW/cm2. All rabbits were followed up by slit lamp examination at day 1 and then at 1, 2, 3 and 4 weeks. The amount of corneal neovascularization was assessed by determination of number and length of visible corneal blood vessels. Three rabbits were selected and sacrificed following each examination (n=6 eyes each) and the corneas were isolated for histopathological examination and documentation.
Significant improvement with regression of the corneal neovascularization was observed both on slit lamp and histological examination, in the PDT treated group. On day 1, the number of vessels was 7.3ḟ0.47 in the non-treated group, decreased to 6.7ḟ0.42 after PDT, with a percentage change of -8.2% (P?0.05). At 1 week, the number of vessels was 8.7ḟ0.45 and significantly decreased to 5.7ḟ0.44 after PDT with a percentage change of -34.5% (P?0.01). At 2 weeks, the number of vessels decreased from 9.3ḟ0.47 to 4.3ḟ0.46 after PDT, with a percentage change of -53.8% (P?0.001). At 3 weeks, , the number of vessels decreased from 10.0ḟ0.81 to 1.7ḟ0.48 after PDT, with a percentage change of -83% ( P?0.001). At 4 weeks there was nearly complete recovery with values of 12.4ḟ0.49 and 1.3ḟ0.47 respectively (-89.5%, P?0.001). Nearly similar confirmatory results were obtained regarding the length of corneal blood vessels. Histological photographic documentation confirmed the disappearance of blood capillaries at the second and third weeks with some irregularities of the stromal lamellae that recovered completely to match the control group at 4 weeks.
PDT for corneal neovascularization is a feasible and effective novel treatment modality. Further clinical trials are needed to precisely determine the dosage and finely tune the laser parameters before a widespread application of the technique.