Egypt. J. Biophys. Biomed. Engng.Vol. 18 , pp. 46 -55 (2017) ُ*Corresponding author :ayman_salah8@yahoo.com DOI: 10.21608/EJBBE.2018.2840.1014 ©2017 National Information and Documentation Centre (NIDOC) The eye is a vital organ which gives us the sense of sight, allowing us to learn more about the surrounding world than we do with any of the other four senses. Cornea is the outermost part of the eye. It is clear with no blood vessels to nourish it but it obtains its nourishments from the tear and aqueous humor. It is an organized group of cells and proteins arranged in fve layers (1) . It provides two-thirds of the total ocular refractory power. Corneal neovascularization (CNV) is considered as one of the most common cause of blindness worldwide (2) . Corneal neovascularization (CNV) is a challenging condition, and because corneal clarity and avascularity are critical for maintaining vision, developing treatments for corneal NV is crucial. Corneal NV occurs as a result of disequilibrium between angiogenic and T HE AIM of the present work is to evaluate the effect of photodynamic therapy (PDT) by using argon laser with rose bengal (Herbs) as a photosensitizer when compared to the Avastin for treatment of corneal neovascularization (CNV) in rabbits. Thirty-Nine Newzealand male rabbits aged 2.5 months and weighing 2.5-3 kg are selected from the animal house of research institute of ophthalmology, Giza, Egypt. Three rabbits are considered as control, and thirty-six rabbits are subjected to corneal neovascularization (CNV) induced by 3 silk sutures at mid-stromal depth approximately 1 mm from the limbus. After four days, sutures are removed and slit lamp examinations are performed to determine the area of CNV. Rabbits with CNV are divided into 3 groups: (1) The frst group left without any treatment (n=12); (2) The second group (n=12 rabbits) were generally anesthetized and rose bengal (C20H4Cl4I4O5) with a dose of 50 mg/Kg was administered by slow intravenous injection in the marginal ear vein. After 15 minutes, rabbit’s eyes were exposed to argon laser (Quantel-Medical, Vitra, France) in a pulsed mode at 532 nm, spot size of 50 μm, pulse duration of 0.2 ms and a power of 150-200 mW/cm 2.; (3) The third group has been treated with subconjunctival injection of 25 mg Avastin (n=12). The rabbits were followed up for 4 weeks and 3 rabbits are selected and sacrifced weekly from each group. The corneas have been isolated for determination of protein content, SDS-poly acrylamide gel electrophoresis, total antioxidant capacity (TAC) and total oxidative capacity (TOC). Final results show that avastin is almost as effective as photodynamic therapy. Keywords: Corneal neovascularization (CNV) , Photodynamic therapy (PDT), Argon laser , Avastin. 5 Effciency of Argon Laser and Bevacizumab (Avastin) in Treatment of Corneal Neovascularization in Experimental Animal Models Mohamed I. El Gohary * , Salwa A. Abdelkawi ** , Aziza A. Hassan *** , Ahmed TS Saif **** and Ayman S. El Shinawy * . * Physics Department, Biophysics Branch, Faculty of Science, Al-Azhar University (Boys); ** Department of Vision Science, Biophysics and Laser Science Unit, Research Institute of Ophthalmology; *** Ophthalmic Unit, National Institute for Laser Enhanced Science, Cairo University, **** Ophthalmology Department, Fayoum University, Egypt. antiangiogenic stimuli (3,4) . Many different types of treatment have been tried previously for corneal neovascularization. The primary treatments of these vessels are the topical corticosteroids and non-steroids anti-inflammatory drugs. However, if the vessels have been established for an extended period, these treatments are ine- ective (5) . In photodynamic therapy, systemically administered porphyrin derivatives accumulate in proliferating endothelial cells. Laser energy is then used to activate the porphyrin derivatives librating cytotoxic oxygen free radicals (6) . This reactive oxygen species (ROS) facilitate the damage of vascular endothelium by activates platelets, leading to the formation of thrombus that occlude the target vessels. Vascular endothelial growth factor (VEGF) is a member of the platelet-