The Anatomy of the Eye is integral to designing effective ocular drug delivery systems (ODDS).
Each structure plays a critical role in vision and presents unique challenges for drug delivery due to physical and dynamic barriers.
Key Structures of the Eye
Cornea:
Function: Refracts light and focuses it onto the retina.
Drug Delivery Barrier: Highly selective, prevents many drugs from penetrating.
Conjunctiva:
Function: Protects the sclera and inner eyelids.
Drug Delivery Role: Provides an alternative absorption route for some drugs.
Sclera:
Function: Maintains the eye's shape and protects inner structures.
Drug Delivery Barrier: Limits penetration of large molecules.
Iris:
Function: Regulates light entering the eye by adjusting pupil size.
Drug Delivery Relevance: Can be targeted for conditions like glaucoma.
Pupil:
Function: Allows light to pass to the lens and retina.
Drug Delivery Note: Accessed indirectly through corneal absorption.
Lens:
Function: Focuses light onto the retina.
Drug Delivery Challenge: Shields posterior segment from anterior drug diffusion.
Ciliary Body:
Function: Adjusts lens shape (accommodation) and produces aqueous humor.
Drug Delivery Target: Key site for treating glaucoma.
Aqueous Humor:
Function: Maintains intraocular pressure and nourishes the eye.
Drug Delivery Challenge: Its flow clears drugs rapidly from the anterior chamber.
Vitreous Humor:
Function: Maintains the eye's shape and supports the retina.
Drug Delivery Target: Often accessed via intravitreal injections for posterior eye diseases.
Retina:
Function: Converts light into electrical signals for the brain.
Drug Delivery Barrier: Blood-retinal barrier restricts systemic drug access.
Optic Nerve:
Function: Transmits visual information to the brain.
Drug Delivery Role: May be targeted in neuroprotective therapies.
Choroid:
Function: Supplies oxygen and nutrients to the retina.
Drug Delivery Barrier: Dense vascularization limits drug diffusion.