ABSTRACT
Diseases related to the posterior segment of the eye, especially due to the aging population in the world, the high incidence of intraocular inflammatory and autoimmune diseases and the advance in understanding the molecular basis of retinal degenerative and genetic diseases, urgently necessitate the development of either new drugs or drug and gene-based drug delivery systems suitable for intraocular applications. The blood-retinal barrier (BRB) that restricts the passage of most of the drugs to the retina through systemic administration makes the development of local assess to the diseased site by intravitreal or subretinal injections of drugs and gene-based drug delivery systems or by intravitreal implants essential for the treatment of vitreoretinal diseases. In this respect, the pharmaceutical basis of drug development, and concepts in drug delivery design, must create appropriate formulations by taking the properties of the target biological compartments or site into consideration. Moreover, knowledge about the posterior part of the eye, especially the BRB and the cells forming this barrier, is necessary for the design of ideal intraocular drug and gene-based delivery systems.
