See below for the drawings.
Layers in the Eye
Each eyeball is surrounded by three distinct layers.
The outer layer in the eye is the sclera, an opaque layer of dense connective tissue. The inner sclera
is located adjacent to the choroid. It contains different types of connective tissue fibers and connective
tissue cells, including macrophages and melanocytes. Anteriorly, the sclera is modified
into a transparent cornea, through which light rays enter the eye.
Vascular Layer (uvea)
Internal to the sclera is the middle or vascular layer (uvea). This layer consists of three parts: a
densely pigmented layer called the choroid, a ciliary body, and an iris. Located in the choroid are
numerous blood vessels that nourish the photoreceptor cells in the retina and structures of the
The innermost lining of the most posterior chamber of the eye is the retina. The posterior three
quarters of the retina is a photosensitive region. It consists of rods, cones, and various interneurons,
cells that are stimulated by and respond to light. The retina terminates in the anterior region
of the eye called the ora serrata, which is the nonphotosensitive part of the retina. This region continues
forward in the eye to line the inner part of the ciliary body and the posterior region of the iris.
Chambers in the Eye
The eye also contains three chambers.
The anterior chamber is a space located between the cornea, iris, and lens.
The posterior chamber is a small space situated between the iris, ciliary process, zonular
fibers, and lens.
The vitreous chamber is a larger, posterior space that is situated behind the lens and zonular
fibers, and surrounded by the retina.
The anterior and posterior chambers are filled with a watery fluid called the aqueous
humor. This fluid is continually produced by the ciliary process located behind the iris.Aqueous
humor circulates from the posterior chamber to the anterior chamber, where it is drained by
veins. The vitreous chamber is filled with the gelatinous substance called the vitreous body.
Photosensitive Parts of the Eye
The photosensitive retina contains numerous cell types organized into numerous and distinct cell
layers. The layer that is sensitive to light contains cells called rods and cones. These cells are stimulated
by light rays that pass through the lens. Leaving the retina are afferent (sensory) axons
(nerve fibers) that conduct light impulses from the retina via the optic nerve to the brain for
The posterior region of the eye also contains a yellowish pigmented spot called the macula
lutea. In the center of the macula lutea is a depression called the fovea. The fovea is devoid of
photoreceptive rods and blood vessels. Instead, the fovea contains a dense concentration of photosensitive
|Retina and Choroid(Hematoxylin-Eosin)|
|Layers of choroid and retina (Hematoxylin-Eosin)|
|Whole eye-sagittal section (Hematoxylin-Eosin)|
|Ciliary body, iris, lens (Hematoxylin-Eosin)|