Rapid Communication - Ophthalmology Case Reports (2022) Volume 6, Issue 1
Translational potential of nanocarriers for ocular medication delivery.
The eye can be broadly divided into the anterior and posterior segments. The anterior segment includes the cornea, conjunctiva, iris, ciliary body, lens, and aqueous humour, while the posterior segment includes the sclera, choroid, retina, and vitreous body. The anterior and posterior segments of the eye are affected by several vision-threatening diseases. To treat eye diseases, topical administration is the preferred non-invasive technique. However, 90% of currently available conventional ophthalmic formulations are eye drops, which are principally administered into the conjunctival cul-de-sac and exhibit poor ocular bioavailability because various anatomical and physiological constraints impede drug delivery to both the anterior and posterior regions of the eye. Physiological barriers (nasolacrimal drainage, lacrimation rate, blinking) are among them, as are anatomical barriers (static and dynamic), efflux pumps, and ocular tissue metabolism. The tear film also serves as a barrier, preventing drug absorption when applied topically. An outside lipid layer, a middle aqueous layer, and an inner mucus layer make up the tear film. As a result, the medication is diluted and wiped away by the tear film. Furthermore, mucin in the tear film produces a hydrophilic layer on the ocular surface's glycocalyx, protecting the eye from cell debris and external substances while also functioning as a barrier to medications delivered.
Author(s): David Penson