Intravitreal Implants

Anatomical diagram of a human eye

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]

Applications

Non-biodegradable implants

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]

Fluocinolone acetonide (Iluvien)^[5]

Biodegradable implants

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]

Dexamethasone (Ozurdex)^[5]
Bimatoprost (Durysta)^[5]

References

↑ "Nanomedicine and drug delivery to the retina: current status and implications for gene therapy". Naunyn-Schmiedeberg's Archives of Pharmacology 395 (12): 1477–1507. December 2022. doi:10.1007/s00210-022-02287-3. PMID 36107200.
↑ ^2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 "Intravitreal Systems For Targeted Drug Delivery To The Posterior Eye Segment: A Systematic Review". Russian Open Medical Journal 11 (2): e0213. 2022-06-25. doi:10.15275/rusomj.2022.0213. https://romj.org/2022-0213.
↑ (in en) Smart Biomaterial Devices (0 ed.). CRC Press. 2016-12-19. doi:10.1201/9781315371559. ISBN 978-1-4987-0701-5. https://www.taylorfrancis.com/books/9781498707015.
↑ ^4.0 ^4.1 ^4.2 "Polymeric Implants for the Treatment of Intraocular Eye Diseases: Trends in Biodegradable and Non-Biodegradable Materials". Pharmaceutics 13 (5): 701. May 2021. doi:10.3390/pharmaceutics13050701. PMID 34065798.
↑ ^5.0 ^5.1 ^5.2 "The Use of Sustained Release Intravitreal Steroid Implants in Non-Infectious Uveitis Affecting the Posterior Segment of the Eye". Ophthalmology and Therapy 11 (2): 479–487. April 2022. doi:10.1007/s40123-022-00456-4. PMID 35092605.

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[1] "Nanomedicine and drug delivery to the retina: current status and implications for gene therapy". Naunyn-Schmiedeberg's Archives of Pharmacology 395 (12): 1477–1507. December 2022. doi:10.1007/s00210-022-02287-3. PMID 36107200.

[:1-2] 2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 "Intravitreal Systems For Targeted Drug Delivery To The Posterior Eye Segment: A Systematic Review". Russian Open Medical Journal 11 (2): e0213. 2022-06-25. doi:10.15275/rusomj.2022.0213. https://romj.org/2022-0213.

[3] (in en) Smart Biomaterial Devices (0 ed.). CRC Press. 2016-12-19. doi:10.1201/9781315371559. ISBN 978-1-4987-0701-5. https://www.taylorfrancis.com/books/9781498707015.

[:2-4] 4.0 ^4.1 ^4.2 "Polymeric Implants for the Treatment of Intraocular Eye Diseases: Trends in Biodegradable and Non-Biodegradable Materials". Pharmaceutics 13 (5): 701. May 2021. doi:10.3390/pharmaceutics13050701. PMID 34065798.

[:0-5] 5.0 ^5.1 ^5.2 "The Use of Sustained Release Intravitreal Steroid Implants in Non-Infectious Uveitis Affecting the Posterior Segment of the Eye". Ophthalmology and Therapy 11 (2): 479–487. April 2022. doi:10.1007/s40123-022-00456-4. PMID 35092605.