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The Eye Depicted & Labeled:
Listed below this diagram of the eye are basic descriptions of all labeled ocular parts (plus a few other key parts/concepts not pictured in the diagram).
Additionally, brief summaries of common optical equipment used by vision specialists (optometrists, ophthalmologists, eye care technicians, etc.) can be found at the bottom of the page.
Although this may seem like lots of detail, it is only scratching the surface of ocular anatomy and optical care!
Anterior Chamber
Function: holds aqueous humor
Composition: aqueous humor (watery, gel-like substance)
Aqueous Humor
Function: Helps maintain the eye's shape
Composition: water, amino acids, and sodium (98-99% water)
Choroid
Function: supplies nutrients and regulates temperature
Composition: tissue and blood vessels
Ciliary Body
Function: helps the eye to focus and produces the aqueous humor solution
Composition: smooth muscle fibers (a.k.a ciliary muscles)
Cornea
Function: protects the eye from outside debris/harmful light and helps direct/focus the amount of light that enters into the eye
Composition: numerous layers of tissue
Fovea
Function: responsible for providing sharp (well-defined) vision
Composition: mostly cone cells
Hyaloid Canal
Function: supplies blood to the lens during early development (afterwards becomes filled with lymph)
Composition: collagen
Iris
Function: helps regulate the amount of light that can enter into the retina by controlling the pupil
Composition: two layers of smooth muscle (the amount of pigment present determines eye color)
Lens
Function: changes its shape to help focus, adjust, and clarify visual objects at varying distances for the retina
Composition: tissue with high protein concentration
Macula
Function: responsible for central vision
Composition: photoreceptor cells (i.e., rods & cones)
Optic Disc
Function: transfers signals between photoreceptor cells and the optic nerve
Composition: combination of numerous tissues
Optic Nerve
Function: communicates visual signals to the brain
Composition: nerve fibers (axons of retinal ganglion cells)
Posterior Chamber
Function: holds aqueous humor
Composition: aqueous humor (watery, gel-like substance)
Pupil
Function: regulates the amount of light that can enter into the retina by changing its size (controlled by the iris)
Composition: hole in the middle of the iris
Retina
Function: converting light energy into electrical energy
Composition: neural, glial, and photoreceptor cellular layers
Retinal Blood Vessels
Function: nourishes the retina
Composition: blood/nutrients
Sclera
Function: helps maintain the eye's shape and prevent injuries
Composition: numerous layers of tissue (same as cornea) and gives the eye its white color
Suspensory Ligaments
Function: holds the lens in place and connects it to the ciliary body
Composition: connective tissue
Uvea
Function: varies based on its individual parts
Composition: comprised of the choroid, iris, and ciliary body
Vitreous Body/Humor
Function: helps maintain the eye's shape
Composition: water, glucose, and charged particles (98-99% water)
Other Key Parts/Concepts of the Eye:
Axons of the Eye
Function: sends electrical nerve impulses from eye to brain
Composition: retinal ganglion cells
Eyelashes & Eyelids
Function: tear lubrication (eyelids) and debris protection (eyelashes/eyelids)
Composition: small hair follicles (eyelashes) and skin/soft tissue (eyelids)
Orbit & Extraocular Muscles
Function: structural support/protection (orbit) and facilitates movement (extraocular muscles)
Composition: bony structure (orbit) and skeletal muscle (extraocular muscles)
Photoreceptors (Rods & Cones)
Function: helps with night vision (rods) and helps with color and daytime vision (cones)
Composition: cellular material for rods and cones
Retinal Ganglion Cells
Function: helps with overall communication between the eye and the brain
Composition: axons and dendrites
Common Eye Care Equipment
Snellen Chart
Penlight
Year Invented - 1862
Inventor - Dr. Herman Snellen (Dutch Ophthalmologist)
Function - Measures visual acuity (i.e., sharpness). It consists of rows of letters that decrease in size, allowing vision specialists to assess how clearly a person can see at a standardized distance, typically 20 feet.
Year Invented - 1899
Inventor - David Misell (British Inventor)
Function - Miniture flashlight that assesses pupil size and reactivity to different levels of brightness, helping evaluate neurological and ocular function.
Phoropter
Slit Lamp
Year Invented - 1922
Inventor - Henry DeZeng (American Inventor)
Function - Measures refractive error and determines a patient’s eyeglasses or contact lens prescription. It contains multiple lenses and filter switches to refine visual clarity and identify the best corrective lens.
Year Invented - 1911
Inventor - Dr. Allvar Gullstrand (Swedish Ophthalmologist)
Function - Projects a thin beam (slit) of light into the eye via a a high-intensity flashlight and high-powered microscope. It allows optometrists and ophthalmologists to examine the cornea, iris, lens, and anterior chamber in detail for ocular health and disease monitoring.
Retinal (Fundus) Camera
Visual Field Analyzer
Year Invented - 1904
Inventor - Dr. Friedrich Dimmer (Austrian Ophthalmologist)
Function - Captures detailed photographs of the retina, optic disc, and blood vessels at the back of the eye. It allows optometrists and ophthalmologists to detect, document, and monitor eye diseases such as diabetic retinopathy, glaucoma, and macular degeneration.
Year Invented - 1984
Inventor - Dr. Mike Patella (American Optometrist) and Anders Heijl (Swedish Professor)
Function - Measures a patient’s visual field (i.e., central and peripheral vision). It helps detect ocular conditions by mapping peripheral vision sensitivity with precise, computerized testing.
Tonometer
Non-Contact Tonometer
Year Invented - 1905
Inventor - Dr. Hjalmar Schiøtz (Norwegian Ophthalmologist)
Summary - Measures intraocular pressure (IOP) in the eye. It helps optometrists and ophthalmologists screen for and monitor glaucoma by detecting abnormal pressure levels that could damage the optic nerve.
Year Invented - 1972
Inventor - Dr. Bernard Grolman (American Optometrist)
Summary - Measures intraocular pressure (IOP) without touching the eye. It uses a brief puff of air to flatten the cornea, providing a quick and painless method to screen for glaucoma and monitor eye health.
Retinoscope
Indirect Ophthalmoscope
Year Invented - 1850
Inventor - Dr. Franciscus Danders (Dutch Ophthalmologist)
Function - Examines the reflection of light from the retina. It helps optometrists and ophthalmologists estimate refractive errors and determine the appropriate eyeglass or contact lens prescription.
Year Invented - 1950
Inventor - Dr. Charles Schepens (Belgian-American Ophthalmologist)
Function - Provides binocular, wide-angle 3D view of the retina. It allows ophthalmologists to examine and diagnose retinal conditions with greater depth and clarity than direct viewing methods.
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