Intravitreal implants are micro device-like inserts injected into the posterior segment of the eye to treat retinal diseases releasing therapeutic drugs at a set rate over a desired period of time. [1] [2] The posterior segment of the eye consists of the sclera, choroid, fovea, vitreous humor, optic nerve, and retina. [3] [4]
Inserts made with non-biodegradable materials such as polymers require a surgical removal of the implant after the end of the treatment period. [2] Examples of these materials consist of polymers such as ethylene-vinyl acetate (EVA), polyvinyl alcohol (PVA), polyurethane (PU) and poly siloxane (PS). [4] An advantage to these non-biodegradable implants is that they do not cause any immune response towards the retina and the release of the drug substance can be controlled by "layering polymers of different permeability." [2]
Biodegradable implants are made of materials, typically, either water-soluble or metabolizable to degrade into un-harmful byproducts which can be safely excreted by the human body. [2] [4] It is important to note the release of the therapeutic drug is determined by the degradation of the implant and the diffusion rate of the drug substance. [2] Indicating that the higher the molecular weight of the polymer and drug substance used, the slower the release of the drug into the vitreous humor. [2]
Intravitreal implants are micro device-like inserts injected into the posterior segment of the eye to treat retinal diseases releasing therapeutic drugs at a set rate over a desired period of time. [1] [2] The posterior segment of the eye consists of the sclera, choroid, fovea, vitreous humor, optic nerve, and retina. [3] [4]
Inserts made with non-biodegradable materials such as polymers require a surgical removal of the implant after the end of the treatment period. [2] Examples of these materials consist of polymers such as ethylene-vinyl acetate (EVA), polyvinyl alcohol (PVA), polyurethane (PU) and poly siloxane (PS). [4] An advantage to these non-biodegradable implants is that they do not cause any immune response towards the retina and the release of the drug substance can be controlled by "layering polymers of different permeability." [2]
Biodegradable implants are made of materials, typically, either water-soluble or metabolizable to degrade into un-harmful byproducts which can be safely excreted by the human body. [2] [4] It is important to note the release of the therapeutic drug is determined by the degradation of the implant and the diffusion rate of the drug substance. [2] Indicating that the higher the molecular weight of the polymer and drug substance used, the slower the release of the drug into the vitreous humor. [2]