“O” selections in the Glossary of Terms for
Anatomy, Physiology & Pathology of the Human Eye

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oblique muscle
either of two muscles, the superior oblique (a long thin muscle that arises just above the margin of the optic foramen, is inserted on the upper part of the eyeball, and moves the eye downward and rotates the top of the eye nasally) or the inferior oblique (a short muscle that arises from the orbital surface of the maxilla, is inserted slightly in front of and below the superior oblique, and moves the eye upward and rotates the top of the eye temporally)

occipital lobe
see lipid layer

oculi unitas or uniter (O.U.)
both eyes working simultaneously as a unit

oculo utro (O.U.)
each eye

oculus dexter (O.D.)
right eye

oculus sinister (O.S.)
left eye

oculus uterque (O.U.)
both eyes

oil layer
see lipid layer

open angle glaucoma
see glaucoma, open angle

ophthalmologist (M.D.)
medical doctor (physician and surgeon) specializing in the structure, functions, and diseases of the eye, treating with medications, surgeries, and lasers

optometric physician (O.D.)
optometrist specializing in the structure, functions, and diseases of the eye, often treating with medications, surgeries, and lasers

optometrist (O.D.)
doctor of optometry concerned with examination, diagnosis, and treatment of the eyes and related structures and with determination and correction of vision problems using lenses and other resources, such as low vision aids and visual therapy

optical infinity
the least distance (simulating a virtually infinite distance) at which there is no significant accommodation by a viewer’s crystalline lens

optic atrophy
degeneration of the optic nerve, causing severe vision loss and even blindness

optic chiasm
optic chiasma; the X-shaped partial decussation on the undersurface of the hypothalamus through which the optic nerves are continuous with the brain

optic disc (or disk)
optic nerve head in the eye, in which no photoreceptors are present, thus resulting in a blind spot in the visual field

optic nerve
cranial nerve II; the sensory nerve which carries electrical impulses from visual stimuli in the retina out of the eye, across the optic chiasm, and to the ventral part of the diencephalon, on their way to the visual cortex in the occipital cortex of the brain for interpretation

optic neuritis
inflammation of the optic nerve within the eyeball (papillitis) or behind the eyeball (retrobulbar optic neuritis)

optic neuropathy
an abnormal and usually degenerative state of the optic nerve

optic neuropathy, ischemic
“stroke” of the optic nerve; a sudden loss of central vision and/or side vision because of reduced blood flow to the optic nerve; can be arteritic (due to an inflammation of the arteries supplying the optic nerve, such as temporal arteritis) or non-arteritic (due to disorders such as diabetes, malignant hypertension, eclampsia (high blood pressure during pregnancy), migraine, and systemic lupus erythematosus, arteriosclerosis, shock, carotid artery disease, and collagen vascular disease)

optic neuropathy, non-ischemic
optic nerve damage caused by such things as toxicity (from overdose of drugs such as barbiturates, DDT, alcohol, lead, aniline dyes, and medical drugs such as digitalis, ergotamine, inderal, and ethambutol), nutritional deficiency, glaucomatous optic nerve disease, and Leber’s hereditary optic neuropathy

optic radiation
the portion of the optic fibers between the lateral geniculate body, located in the thalamus of the brain, and the striate cortex (or Brodmann’s Area 17) in the occipital lobe of the brain

optic tract
the portion of the optic fibers between the optic chiasm and the lateral geniculate body, located in the thalamus of the brain

a maker of or dealer in optical items and instruments; a person who reads prescriptions for visual correction, orders lenses, and dispenses eyeglasses and contact lenses

a doctor of optometry who examines the eyes and associated structures to determine refractive errors, extraocular muscle imbalances, and pathological conditions, prescribing glasses or contact lenses, eye exercises, and in some cases topical and systemic drugs to treat ocular disorders

ora seratta
the serrated junction between the retina and the ciliary body; marks the transition from the simple non-photosensitive area of the retina to the complex, multi-layered photosensitive region

eye socket; the bony cavity of the skull that contains the eye

outer nuclear layer
layer of the retina containing the cell bodies of the photoreceptors (cones and rods)

outer plexiform layer
layer of the retina containing the axons of photoreceptor (cone and rod) cells, as well as the dendrites of horizontal cells and bipolar cells

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