The eye is a complex organ with various structures, each playing a critical role in vision.
For the context of Ocular Drug Delivery Systems, understanding the anatomy is essential to ensure the effective delivery of therapeutics.
Here's a brief overview of the eye's anatomy:
1. Cornea:
The clear, dome-shaped front surface of the eye. It refracts light entering the eye and contributes to focus.
2. Conjunctiva:
A thin, clear tissue that covers the white part of the eye (sclera) and the inner surface of the eyelids. It provides a protective barrier.
3. Sclera:
The white, outer protective layer of the eye. It maintains the shape of the eye.
4. Iris:
The colored part of the eye. It regulates the amount of light entering the eye by adjusting the size of the pupil.
5. Pupil:
The central opening in the iris. It allows light to enter the eye and reach the retina.
6. Lens:
A clear, biconvex structure behind the iris. It focuses light onto the retina.
7. Ciliary Body:
Contains the muscles that change the shape of the lens (accommodation) and produces aqueous humor.
8. Aqueous Humor:
The clear fluid filling the anterior chamber (between the cornea and the iris) and the posterior chamber (between the iris and the lens). It nourishes the eye and maintains intraocular pressure.
9. Vitreous Humor:
A clear, jelly-like substance that fills the space between the lens and the retina. It helps maintain the shape of the eye and ensures the retina remains flat against the back of the eye.
10. Retina:
The light-sensitive layer at the back of the eye. It contains photoreceptor cells (rods and cones) that convert light into electrical signals.
11. Optic Nerve:
Carries visual information from the retina to the brain.
12. Choroid:
A layer filled with blood vessels, lying between the retina and sclera. It provides oxygen and nutrients to the outer layers of the retina.
• For ocular drug delivery, understanding these structures is crucial.
• The physical barriers (like the cornea and sclera) and dynamic barriers (like the flow of aqueous humor) present challenges to the effective delivery of drugs to specific parts of the eye.
• As such, specialized delivery systems are developed to overcome these barriers and provide therapeutic concentrations at the target site.