Vasculature: primarily derived from the ophthalmic artery.Orbit: bony structure that contains the eyeball and several openings for the passage of nerves, vessels, and lymphatics.Choroid : supplies the retina with nutrients.Retina: pigment cells translate light signals into neuronal signals that travel to the brain via the optic nerve ( CN II).

Vitreous chamber : between lens and retina, contains vitreous humor.

Posterior chamber: between lens and iris.

Anterior chamber: between cornea and iris.

Lens : refracts light and focuses it on the retina by accommodating its convexity according to the distance of objects focused on.

Iris : regulates the amount of light impinging on the retina.

Nervous tunic (innermost layer): retina.

Vascular tunic/ uvea (middle layer): choroid, ciliary body, pigmented epithelium, iris.

Fibrous tunic (external layer): cornea and sclera.

Extraocular muscles connect the eyeball to the orbit and control movement of the eyelid as well as the eye. The development of the eye and accessory visual structures occurs between the 3 rd and 10 th week of embryonic development. The lacrimal gland secretes tear fluid, which reduces friction and cleans the eye, while the eyelid protects the eyeball from excessive light, dryness, and foreign bodies. Accessory visual structures include the lacrimal gland and the eyelid. The eyeball lies within the bony orbit, which has several openings for the passage of neurovascular structures. Cranial nerves mediate vision ( CN II) and eye movement ( CN III, IV, VI), while accommodation is mediated by fibers of the autonomic nervous system. The eye receives its arterial supply from branches of the ophthalmic artery and drains into the ophthalmic vein. The refractive media, comprising the cornea, lens, aqueous humor, and vitreous body, directs and refracts light to the posterior region of the retina. The visual pathway begins with the first-order neurons of the retina, retinal rods and cones, which convert the optical image into neuronal signals, which are transmitted to the brain. Functionally, the eye can be divided into structures that perceive light (components of the visual pathway) and structures that refract light (refractive media).

The anterior eye is subdivided further into two chambers: the posterior chamber (between lens and iris) and the anterior chamber (between iris and cornea), both of which are filled with aqueous humor. The lens is suspended between the pupil and the vitreous body by ligaments attached to the ciliary body. The eye is further divided into an anterior segment, which contains the lens and structures anterior to it, and a posterior segment, which contains the vitreous humor and the retina. Anatomically, the outer portion of the eye is divided into three layers: the fibrous tunic ( cornea and sclera), the vascular tunic ( choroid, iris, and ciliary body), and the nervous tunic ( retina). The eyes are paired, sensory organs that enable vision.