الفهرس 
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Abstract
Gene therapy is a powerful and promising tool for replacement or inactivation of abnormal genes in some reported ocular diseases .The ideal gene delivery vector would efficiently and specially transfer the gene to target cells and obtain high level of gene expression .In addition, the vector would not evoke an immune response and would be non toxic to the recipient (Zack et al., 1993)
Improving the transfer efficiency and prolonging the duration of transgene expression will be accomplished through a better understanding of the mechanisms by which vectors gain access to cells, what factors influence their access, and what factors can tribute to the loss of transgene expression (Feuerbach et al., 1996)
Vector used to deliver the specific gene to the target cells include viral and non viral vectors reaching the target cells by in vivo, ex vivo or in situ approaches (Da Cruze et al., 1997)
Hereditary retinal dystrophy is a target for gene therapy by controlling apoptosis achieved by using gene which antagonize apoptosis e.g. Hereditary retinal dystrophy is a target for gene therapy by controlling apoptosis achieved by using gene which antagonize apoptosis e.g.by using growth factors as ciliary neurotrophic factor (CNT F) using direct intravitreal injection or indirectly using recombinant adenovirus (rAV) or recombinant adenoassociated viral(rAAV) vectors (Chen et al., 1996)
In 1996,Bennett and his associates use (rAV) vector to deliver B. photodiesterase (B.PDE) gene to the photoreceptor cells by subretinal injection in retinal degeneration (rd) mice and observe an increase in the number of payers of cells indicating success of the experiment (Bennett et al., 1996)
In 1999,Nobutsugu and his associates together with Hurwitz and his associates used herpes simplex virus thumidine himase (Hsv-TK) gene delivered by retroviral vector to suppress tumorgenesis in prepared retinoblastoma (rb) cell cultures and observe inhibition of the humor cells. Also, experimental mice were used by intraperitoneal injection of Rb cells followed by intraocular injection of significant prolongation of progression .Free survival in comparison to the untreated ones (Nobutsugu et al., 1999)
In age related macular degeneration Intravitreal injection of AAV vector mainly results in the transduction of the ganglion cells, whereas subretinal administration results in the transduction of the RPE and the photoreceptors. Bovine immunodeficiency lentivirus vector similarly has been used for subretinal gene delivery in mice. With the advent of antineovascular pharmacotherapy, the visual prognosis of patients with wet AMD has improved. However, the current standard-of-care therapies require monthly intravitreal injections by a retina specialist due to their short half-life in the vitreous. Besides the logistic difficulties ,the patient’s discomfort, cataract formation, endophthalmitis, vitreous hemorrhage and retinal detachment. (Pechan et al., 2008).
To study the mechanism by which the genetic abnormalities lead to primary open angle glaucoma (POAG), Masanori and his associates in 1998 used non viral vector,The hemagglutinationing virus of Japan liposomes to transfer lacz DNA and flourscin iso –thiocyanate (FITC) labeled phosphor thioate oligonucleotides genes into the anterior chamber of rats and monlceys and found great result in controlling the resistance to aqueous humor out flow thus controlling POAG (Masanori et al., 1998)
Finally, gene therapy is progressing rapidly because of the better understanding of genetic disease. Methods suggest that it is feasible to insert genes where they are missing or defective and suppress gene whene they produce abnormal proteins. They are forming the basis of a completely new type of treatment that may be used to a group of wide spread ocular disease that currently have no cure (Bennett et al., 1996)