Eye Anatomy & Equipment

The Human Eye Depicted & Labeled:

The eye is an incredibly intricate part of the human body. Alongside this ocular diagram are brief summaries of all the labeled parts pictured (as well as some other key anatomical parts or concepts not included).

Additionally, at the bottom of the page, are summaries of a few common optical tools used by many different vision specialists. Although this may seem like a lot of information, in fact, it is only scratching the surface of the detail surrounding the anatomy and care of the eye.

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 (Not Labeled):

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 - 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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