In the anatomy of the eye, the fibrous outer layer consists of the cornea and the sclera. The cornea is the clear domed part at the front of the eye, while the sclera is the white of the eye, providing structural support. The conjunctiva is a fine mucus membrane covering the sclera and providing protection and lubrication to the front of the eye.
The vascular layer is composed of the choroid, iris, and ciliary body. The iris controls the amount of light that enters the eye through the pupil and has two types of muscles: constrictor and dilator. The lens receives and focuses light on the retina, which contains photoreceptor cells that transform light waves into electrical signals for the brain to interpret. The eye is divided into two segments: the anterior segment and the posterior segment. The anterior segment contains a fluid called aqueous humor produced by the ciliary body and drained by the Canal of Schlemm. The posterior segment is filled with a jelly-like substance called vitreous humor, which helps maintain the eye's shape and absorbs shock.
<ul> <li>Anatomy of the eye <ul> <li>Fibrous outer layer <ul> <li>Cornea: clear domed part at the front of the eye</li> <li>Sclera: white of the eye, provides structural support</li> <li>Conjunctiva: fine mucus membrane covering the sclera, provides protection and lubrication</li> </ul> </li> <li>Vascular layer <ul> <li>Choroid: lines the inside surface of the eye</li> <li>Iris: controls the amount of light entering the eye through the pupil, has constrictor and dilator muscles</li> <li>Ciliary body: contains muscles that manipulate the lens, produces aqueous humor</li> </ul> </li> <li>Lens: receives and focuses light on the retina</li> <li>Retina: in inner layer; contains photoreceptor cells that transform light waves into electrical signals for the brain to interpret</li> <li>Eye segments <ul> <li>Anterior segment: contains aqueous humor produced by the ciliary body and drained by the Canal of Schlemm</li> <ul> <li>Anterior segment separated into anterior chamber and posterior chamber (note anterior & posterior "chambers" vs "segments")</li> </ul> <li>Posterior segment: filled with vitreous humor, which maintains the eye's shape and absorbs shock</li> </ul> </li> </ul> </li> </ul>
The eye can be divided into three main layers: the fibrous outer layer, the vascular middle layer, and the inner layer. The main structures of the eye include the cornea, sclera, conjunctiva, iris, ciliary body, retina, aqueous humor, and vitreous humor.
The cornea and sclera make up the fibrous outer layer of the eye. The cornea is a transparent structure at the front of the eye that helps to focus light entering the eye. The sclera, also known as the "white of the eye," is a tough, opaque tissue that provides support and protection for the eye. The conjunctiva is a thin, transparent layer of tissue that covers the front of the sclera and the inside of the eyelids.
The iris is a pigmented circular structure that controls the amount of light entering the eye by adjusting the size of the pupil. The ciliary body is a muscular structure that produces the aqueous humor, a clear fluid that fills the anterior chamber of the eye, and is responsible for controlling the shape of the lens for accommodation and focusing.
The retina is a light-sensitive layer of tissue that lines the back of the eye. It is responsible for converting light into electrical signals which are then sent to the brain via the optic nerve, allowing us to perceive visual images. The retina consists of several cell types, including photoreceptors (rods and cones), bipolar cells, and ganglion cells.
The aqueous humor is a clear fluid found in the anterior and posterior chambers of the eye, between the cornea and lens. It provides nutrients to the avascular cornea and lens and helps to maintain the intraocular pressure. The vitreous humor is a clear, gel-like substance that fills the space between the lens and retina, making up about two-thirds of the eye's volume. It maintains the shape of the eye and provides structural support for the retina.