124 relations: Absolute threshold, Aging-associated diseases, Anterior chamber of eyeball, Antioxidant, Aperture, Aqueous humour, Arcus senilis, Astigmatism, Blind spot (vision), Blinking, Cataract, Cataract surgery, Central retinal artery, Central retinal vein, Choroid, Ciliary body, Ciliary muscle, Ciliary processes, Circadian rhythm, Computer monitor, Cone cell, Conjunctiva, Contact lens, Contrast ratio, Cornea, Corneal transplantation, Corrective lens, Dermatochalasis, Dura mater, Ectropion, Encyclopædia Britannica Ultimate Reference Suite, Entrainment (chronobiology), Entrance pupil, Entropion, Eye, Eye care professional, Eye chart, Eye color, Eye disease, Eye examination, Eye strain, Eyeglass prescription, Far-sightedness, Feedback, Fibrous tunic of eyeball, Field of view, Floater, Fovea centralis, General practitioner, Hyaloid canal, ..., Inferior oblique muscle, Inferior rectus muscle, Intrinsically photosensitive retinal ganglion cells, Iris (anatomy), Iris dilator muscle, Iris recognition, Iris sphincter muscle, John Wiley & Sons, Knobloch syndrome, Lacrimal caruncle, Lateral rectus muscle, Lens (anatomy), Lens (optics), Light, Lutein, Macula of retina, Macular degeneration, Mammalian eye, Medial rectus muscle, Melatonin, Multiple chemical sensitivity, Muscle, Near-sightedness, Ocularist, Oculolinctus, Oculoplastics, Ophthalmology, Optic disc, Optic nerve, Optician, Optokinetic response, Optometry, Ora serrata, Organ (anatomy), Orthoptics, Paraphilia, Peter Wiedemann, Photon, Photoreceptor cell, Posterior chamber of eyeball, Posterior vitreous detachment, Presbyopia, Ptosis (eyelid), Pupil, Reflex, Refractive surgery, Retina, Retinal detachment, Rheum, Rod cell, Saccade, Schlemm's canal, Sclera, Sensory nervous system, Sick building syndrome, Sleep, Snellen chart, Spectral sensitivity, Superior oblique muscle, Superior rectus muscle, Tenon's capsule, Throat irritation, University of California, Los Angeles, Uvea, Vergence, Vestibulo–ocular reflex, Vision therapy, Visual acuity, Visual perception, Vitreous body, Volatile organic compound, Vorticose veins, Zeaxanthin, Zonule of Zinn. Expand index (74 more) » « Shrink index
In neuroscience and psychophysics, an absolute threshold was originally defined as the lowest level of a stimulus – light, sound, touch, etc.
An aging-associated disease is a disease that is most often seen with increasing frequency with increasing senescence.
The anterior chamber (AC) is the fluid-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium.
Antioxidants are molecules that inhibit the oxidation of other molecules.
In optics, an aperture is a hole or an opening through which light travels.
The aqueous humour is a transparent, watery fluid similar to plasma, but containing low protein concentrations.
Arcus senilis is an old age syndrome where there is a white, grey, or blue opaque ring in the corneal margin (peripheral corneal opacity), or white ring in front of the periphery of the iris.
Astigmatism is a type of refractive error in which the eye does not focus light evenly on the retina.
A blind spot, scotoma, is an obscurity of the visual field.
Blinking is a bodily function; it is a semi-autonomic rapid closing of the eyelid.
A cataract is a clouding of the lens in the eye which leads to a decrease in vision.
Cataract surgery is the removal of the natural lens of the eye (also called "crystalline lens") that has developed an opacification, which is referred to as a cataract.
The central retinal artery (retinal artery) branches off the ophthalmic artery, running inferior to the optic nerve within its dural sheath to the eyeball.
The central retinal vein (retinal vein) is a short vein that runs through the optic nerve, leaves the optic nerve 10 mm from the eyeball and drains blood from the capillaries of the retina into either superior ophthalmic vein or into the cavernous sinus directly.
The choroid, also known as the choroidea or choroid coat, is the vascular layer of the eye, containing connective tissues, and lying between the retina and the sclera.
Christmas is an annual festival commemorating the birth of Jesus Christ,Martindale, Cyril Charles.
The Christmas season, also called the festive season, or the holiday season (mainly in the U.S. and Canada; often simply called the holidays),, is an annually recurring period recognized in many Western and Western-influenced countries that is generally considered to run from late November to early January.
Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus.
Christmas traditions vary from country to country.
The ciliary body is a part of the eye that includes the ciliary muscle, which controls the shape of the lens, and the ciliary epithelium, which produces the aqueous humor.
The ciliary muscle is a ring of smooth muscleSchachar, Ronald A. (2012). "Anatomy and Physiology." (Chapter 4). in the eye's middle layer (vascular layer) that controls accommodation for viewing objects at varying distances and regulates the flow of aqueous humour into Schlemm's canal. It changes the shape of the lens within the eye, not the size of the pupil which is carried out by the sphincter pupillae muscle and dilator pupillae.
The ciliary processes are formed by the inward folding of the various layers of the choroid, i.e., the choroid proper and the lamina basalis, and are received between corresponding foldings of the suspensory ligament of the lens.
A circadian rhythm is any biological process that displays an endogenous, entrainable oscillation of about 24 hours.
A computer monitor is an output device which displays information in pictorial form.
Cone cells, or cones, are one of three types of photoreceptor cells in the retina of mammalian eyes (e.g. the human eye).
The conjunctiva lines the inside of the eyelids and covers the sclera (the white of the eye).
A contact lens, or simply contact, is a thin lens placed directly on the surface of the eye.
The contrast ratio is a property of a display system, defined as the ratio of the luminance of the brightest color (white) to that of the darkest color (black) that the system is capable of producing.
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber.
Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue (the graft).
A corrective lens is a lens typically worn in front of the eye to improve vision.
Dermatochalasis is a medical condition, defined as an excess of skin in the upper or lower eyelid, also known as "baggy eyes." It may be either an acquired or a congenital condition.
Dura mater, or dura, is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord.
Ectropion is a medical condition in which the lower eyelid turns outwards.
Encyclopædia Britannica Ultimate Reference Suite is an encyclopædia based on the Encyclopædia Britannica and published by Encyclopædia Britannica, Inc..
Entrainment, within the study of chronobiology, occurs when rhythmic physiological or behavioral events match their period to that of an environmental oscillation.
In an optical system, the entrance pupil is the optical image of the physical aperture stop, as 'seen' through the front of the lens system.
Entropion is a medical condition in which the eyelid (usually the lower lid) folds inward.
Eyes are organs of the visual system.
An eye care professional (ECP) is an individual who provides a service related to the eyes or vision.
An eye chart is a chart used to measure visual acuity.
Eye color is a polygenic phenotypic character determined by two distinct factors: the pigmentation of the eye's iris and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris.
This is a partial list of human eye diseases and disorders.
An eye examination is a series of tests performed by an ophthalmologist (medical doctor), optometrist, or orthoptist assessing vision and ability to focus on and discern objects, as well as other tests and examinations pertaining to the eyes.
Eye strain, also known as asthenopia (from Greek asthen-opia, ἀσθεν-ωπία, "weak-eye-condition"), is an eye condition that manifests through nonspecific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache, and occasional double vision.
An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist or ophthalmologist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient.
Far-sightedness, also known as hyperopia, is a condition of the eye in which light is focused behind, instead of on, the retina.
Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop.
The sclera and cornea form the fibrous tunic of the bulb of the eye; the sclera is opaque, and constitutes the posterior five-sixths of the tunic; the cornea is transparent, and forms the anterior sixth.
The field of view is the extent of the observable world that is seen at any given moment.
Floaters are deposits of various size, shape, consistency, refractive index, and motility within the eye's vitreous humour, which is normally transparent.
The fovea centralis is a small, central pit composed of closely packed cones in the eye.
In the medical profession, a general practitioner (GP) is a medical doctor who treats acute and chronic illnesses and provides preventive care and health education to patients.
Hyaloid canal (Cloquet's canal and Stilling's canal) is a small transparent canal running through the vitreous body from the optic nerve disc to the lens.
The inferior oblique muscle or obliquus oculi inferior is a thin, narrow muscle placed near the anterior margin of the floor of the orbit.
The inferior rectus muscle is a muscle in the orbit.
Intrinsically photosensitive retinal ganglion cells (ipRGCs), also called photosensitive retinal ganglion cells (pRGC), or melanopsin-containing retinal ganglion cells (mRGCs), are a type of neuron in the retina of the mammalian eye.
In humans and most mammals and birds, the iris (plural: irides or irises) is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina.
The iris dilator muscle (pupil dilator muscle, pupillary dilator, radial muscle of iris, radiating fibers), is a smooth muscle of the eye, running radially in the iris and therefore fit as a dilator.
Iris recognition is an automated method of biometric identification that uses mathematical pattern-recognition techniques on video images of one or both of the irises of an individual's eyes, whose complex patterns are unique, stable, and can be seen from some distance.
The iris sphincter muscle (pupillary sphincter, pupillary constrictor, circular muscle of iris, circular fibers) is a muscle in the part of the eye called the iris.
John Wiley & Sons, Inc., also referred to as Wiley, is a global publishing company that specializes in academic publishing.
Knobloch syndrome is a rare genetic disorder presenting severe eyesight problems and often a defect in the skull.
The lacrimal caruncle, or caruncula lacrimalis, is the small, pink, globular nodule at the inner corner (the medial canthus) of the eye.
The lateral rectus muscle is a muscle on the lateral side of the eyeball in the orbit.
The lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina.
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction.
Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.
Lutein (Random House Webster's Unabridged Dictionary. from Latin luteus meaning "yellow") is a xanthophyll and one of 600 known naturally occurring carotenoids.
The macula or macula lutea is an oval-shaped pigmented area near the center of the retina of the human eye and some other animalian eyes.
Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field.
Mammals normally have a pair of eyes.
The medial rectus muscle is a muscle in the orbit.
Melatonin, also known as N-acetyl-5-methoxy tryptamine, is a hormone that is produced by the pineal gland in animals and regulates sleep and wakefulness.
Multiple chemical sensitivity (MCS), also known as idiopathic environmental intolerances (IEI), is a disputed chronic condition characterized by symptoms that the affected person attributes to low-level exposures to commonly used chemicals.
Muscle is a soft tissue found in most animals.
Near-sightedness, also known as short-sightedness and myopia, is a condition of the eye where light focuses in front of, instead of on, the retina.
New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.
New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.
In the Gregorian calendar, New Year's Eve (also known as Old Year's Day or Saint Sylvester's Day in many countries), the last day of the year, is on 31 December which is the seventh day of Christmastide.
An ocularist is someone who specializes in the fabrication and fitting of ocular prostheses for people who have lost an eye or eyes due to trauma or illness.
Oculolinctus, also known as "worming" or eyeball-licking fetishism, refers to the paraphilic practice of licking eyeballs for erotic gratification.
Oculoplastics, or oculoplastic surgery, includes a wide variety of surgical procedures that deal with the orbit (eye socket), eyelids, tear ducts, and the face.
Ophthalmology is a branch of medicine and surgery (both methods are used) that deals with the anatomy, physiology and diseases of the eyeball and orbit.
The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye.
The optic nerve, also known as cranial nerve II, is a paired nerve that transmits visual information from the retina to the brain.
An optician, or dispensing optician, is a technical practitioner who designs, fits and dispenses corrective lenses for the correction of a person's vision.
The optokinetic response is a combination of a slow-phase and fast-phase eye movements.
Optometry is a health care profession which involves examining the eyes and applicable visual systems for defects or abnormalities as well as the medical diagnosis and management of eye disease.
The ora serrata is the serrated junction between the retina and the ciliary body.
Organs are collections of tissues with similar functions.
Orthoptics is a profession allied to eye care profession whose primary emphasis is the diagnosis and non-surgical management of strabismus (wandering eye), amblyopia (lazy eye) and eye movement disorders.
Paraphilia (previously known as sexual perversion and sexual deviation) is the experience of intense sexual arousal to atypical objects, situations, fantasies, behaviors, or individuals.
Peter Wiedemann (born 23 October 1953 in Erlangen, West Germany) is a German ophthalmologist, specialist in medical and surgical retina and head at the Department of Ophthalmology at the Leipzig University, Germany, since 1993.
The photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles).
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction.
The posterior chamber is a narrow space behind the peripheral part of the iris, and in front of the suspensory ligament of the lens and the ciliary processes.
A posterior vitreous detachment (PVD) is a condition of the eye in which the vitreous membrane separates from the retina.
Presbyopia is a condition associated with the aging of the eye that results in progressively worsening ability to focus clearly on close objects.
Ptosis (/ˈtoʊsɪs/) is a drooping or falling of the upper eyelid.
The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina.
A reflex, or reflex action, is an involuntary and nearly instantaneous movement in response to a stimulus.
Refractive eye surgery is any eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses.
The retina is the innermost, light-sensitive "coat", or layer, of shell tissue of the eye of most vertebrates and some molluscs.
Retinal detachment is a disorder of the eye in which the retina separates from the layer underneath.
Rheum (from Greek: ῥεῦμα rheuma "a flowing, rheum"), also known as gound, is thin mucus naturally discharged from the eyes, nose, or mouth during sleep (cf. mucopurulent discharge).
Rod cells are photoreceptor cells in the retina of the eye that can function in less intense light than the other type of visual photoreceptor, cone cells.
A saccade (French for jerk) is a quick, simultaneous movement of both eyes between two or more phases of fixation in the same direction.
Schlemm's canal is a circular lymphatic-like vessel in the eye that collects aqueous humor from the anterior chamber and delivers it into the episcleral blood vessels via aqueous veins.
The sclera, also known as the white of the eye, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some elastic fiber.
The sensory nervous system is a part of the nervous system responsible for processing sensory information.
Sick building syndrome (SBS) is a medical condition where people in a building suffer from symptoms of illness or feel unwell for no apparent reason.
Sleep is a naturally recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with surroundings.
A Snellen chart is an eye chart that can be used to measure visual acuity.
Spectral sensitivity is the relative efficiency of detection, of light or other signal, as a function of the frequency or wavelength of the signal.
The superior oblique muscle, or obliquus oculi superior, is a fusiform muscle originating in the upper, medial side of the orbit (i.e. from beside the nose) which abducts, depresses and internally rotates the eye.
The superior rectus muscle is a muscle in the orbit.
The fascia bulbi (also known as the capsule of Tenon and the bulbar sheath) is a thin membrane which envelops the eyeball from the optic nerve to the limbus, separating it from the orbital fat and forming a socket in which it moves.
Throat irritation can refer to a dry cough, a scratchy feeling at the back of the throat, a sensation of a lumpy feeling, something stuck at the back of the throat, or possibly a feeling of dust in the throat.
The University of California, Los Angeles (UCLA) is a public research university in the Westwood district of Los Angeles, United States.
The uvea (/ˈjuːvɪə/) (Lat. uva, grape), also called the uveal layer, uveal coat, uveal tract, vascular tunic or vascular layer is the pigmented middle of the three concentric layers that make up an eye. The name is possibly a reference to its reddish-blue or almost black colour, wrinkled appearance and grape-like size and shape when stripped intact from a cadaveric eye. Its use as a technical term in anatomy and ophthalmology is relatively modern.
A vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision.
The vestibulo-ocular reflex (VOR) is a reflex, where activation of the vestibular system causes eye movement.
Vision therapy (also known as vision training, or VT) is used to improve vision skills such as eye movement control, eye coordination, contrast sensitivity, and perception.
Visual acuity (VA) commonly refers to the clarity of vision.
Visual perception is the ability to interpret the surrounding environment using light in the visible spectrum reflected by the objects in the environment.
The vitreous body is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates.
Volatile organic compounds (VOCs) are organic chemicals that have a high vapor pressure at ordinary room temperature.
The vorticose veins, referred to clinically as the vortex veins, drain the ocular choroid.
Zeaxanthin is one of the most common carotenoid alcohols found in nature.
The zonule of Zinn (Zinn's membrane, ciliary zonule) (after Johann Gottfried Zinn) is a ring of fibrous strands forming a zonule (little band) that connects the ciliary body with the crystalline lens of the eye.
2018 has been designated as the third International Year of the Reef by the International Coral Reef Initiative.
2019 (MMXIX) will be a common year starting on Tuesday of the Gregorian calendar, the 2019th year of the Common Era (CE) and Anno Domini (AD) designations, the 19th year of the 3rd millennium, the 19th year of the 21st century, and the 10th and last year of the 2010s decade.