Human health and medicine

Vision Screening

Vision screening (eye test) is a short check of near and far vision, via eye charts or photoscreeners, to flag people needing full eye exams. USPSTF recommends it at ages 3-5 for amblyopia; WHO backs school-age screening every 1-2 years under SPECS 2030.

VISION study

VISION (Vascular Events in Noncardiac Surgery Patients Cohort Evaluation), NCT00512109, McMaster-led international cohort of 40,004 patients that defined MINS and linked postoperative troponin elevation to 30-day mortality.

Vision Tests

Vision tests (eye tests, vision screening) check near and far vision, usually with Snellen or similar charts, to detect amblyopia, strabismus, and refractive error; accuracy varies by test, age, and screener, and abnormal results require comprehensive eye exams.

VISION trial

VISION trial (NCT03511664): phase 3 trial of 177Lu-PSMA-617 (Pluvicto) plus standard care in PSMA-positive metastatic castration-resistant prostate cancer; 831 randomized, survival 15.3 vs 11.3 months; distinct from ophthalmology, stroke, and tepotinib VISION trials.

Vismodegib

Vismodegib (Erivedge), first-in-class oral Smoothened inhibitor approved by FDA in 2012 and EMA in 2013 for advanced basal cell carcinoma; 150 mg daily; ERIVANCE ORR 30-43%, common effects muscle spasms, alopecia, dysgeusia.

Visual acuity

Visual acuity (VA): the eye's spatial resolving capacity, measured as the reciprocal of the minimum angle of resolution; 20/20 equals 1 arcmin. Tested with Snellen, Landolt C, and logMAR/ETDRS charts.

Visual agnosia

Visual agnosia: inability to recognize visually presented objects despite normal vision, language, and memory, with intact recognition by touch. Subtypes are apperceptive and associative (Lissauer 1890, Seelenblindheit), plus category-selective forms like prosopagnosia.

Visual deprivation nystagmus

Visual deprivation nystagmus, also called amaurotic or ocular nystagmus, is involuntary eye movement caused by binocular visual loss, typically infantile cataract during the sensitive period; ICD-11 code 9C84.50.

Visual discomfort

Visual discomfort (asthenopia, eye strain; ICD-11 9D50) is pain or discomfort in or around the eyes with headache and nausea, triggered by stripes, flicker, and glare, linked to excessive visual cortex activity.

Oct 20, 2026

Visual Evoked Potentials

Visual evoked potentials (VEPs, visual evoked responses) are averaged EEG signals from the occipital cortex in response to pattern or flash stimuli, used clinically to assess optic nerve and visual pathway function, notably prolonged P100 latency in optic neuritis and multiple sclerosis.

Visual field

Visual field: the full area visible with fixed gaze, about 160 degrees horizontal per eye. Measured by perimetry (Goldmann, Humphrey SAP, kinetic, microperimetry); field defect patterns localize glaucoma and neurologic lesions.

Visual field testing

Visual field testing measures how sensitive vision is to light across the field, most commonly with automated perimetry, to detect and monitor glaucoma and other eye or neurological disease.

Visual floaters

Visual floaters (vitreous floaters, myodesopsia) are shadows on the retina cast by clumps in the eye's vitreous gel, usually from age-related posterior vitreous detachment; sudden new floaters with flashes can signal retinal tear or detachment.

Visual hallucinations

Visual hallucinations are the perception of objects or events in the absence of an external stimulus, occurring in eye disease, neurologic disorders, toxic states, and psychiatric illness.

Oct 20, 2026

Visual impairment

Vision impairment including blindness (ICD-11 9D90) is reduced vision from eye conditions, graded by visual acuity. At least 2.2 billion people affected; leading causes are refractive error and cataract.

Visual inspection with acetic acid

Visual inspection with acetic acid (VIA) is a point-of-care screening method for cervical precancer in which dilute acetic acid is swabbed on the cervix and read by eye.

Visual phototransduction

Visual phototransduction, also called the phototransduction cascade, is the process by which retinal rod and cone cells convert absorbed light into electrical responses via a G protein cascade.

Visual prosthesis

Visual prosthesis (bionic eye): implantable device restoring rudimentary sight by electrically stimulating surviving retinal or cortical neurons; approved devices include Argus II, IRIS II, Alpha IMS/AMS; acuity stays below legal blindness.

Visual reinforcement audiometry

Visual reinforcement audiometry is a behavioral hearing test in which infants are conditioned to turn toward sound for a visual reward, used from about 6 to 24 months.

Visual release hallucinations

Visual release hallucinations, or Charles Bonnet syndrome, are complex purely visual hallucinations in people with vision loss and intact cognition, caused by cortical release after deafferentation, often ceasing when sight improves.

Visual snow syndrome

Visual snow syndrome (VSS), also called visual snow, is a chronic neurological condition of continuous pan-field visual static plus palinopsia, entoptic phenomena, photophobia, or nyctalopia; ICHD-3 criteria, ~2% prevalence, cortical hyperexcitability, and lamotrigine as best-evidence treatment distinguish it.

Visual system

Visual system: the neural pathway converting light into perception, from retinal phototransduction through optic nerve, chiasm, LGN, and visual cortex; also called the visual pathway, with retinotopic organization and localizable field defects.

Vital Capacity

Vital capacity (VC), including forced (FVC), slow (SVC), and inspiratory (IVC) variants, is the maximum air exhaled after a maximal inspiration, defined by John Hutchinson in 1846 and central to spirometric diagnosis of restrictive and obstructive lung disease.

Vital pulp therapy

Vital pulp therapy (VPT) is a set of dental treatments that preserve a tooth's living pulp instead of removing it, using pulp capping and pulpotomy.

Vital signs

Vital signs: body temperature, pulse, respiratory rate, blood pressure, and often oxygen saturation and pain, the core physiological measurements used in clinical assessment, early warning scores such as NEWS2, and detecting patient deterioration.

Vitamin

Vitamins: 13 essential organic nutrients (A, C, D, E, K, B complex) needed in small amounts for normal cell function, split into fat-soluble and water-soluble groups, obtained from food, sunlight, supplements, and fortification.

Vitamin A

Vitamin A is a group of fat-soluble retinoids, primarily retinol and retinyl esters, needed for vision, immune function, and growth. Deficiency remains a leading cause of preventable childhood blindness.

Vitamin A deficiency

Vitamin A deficiency (VAD, xerophthalmia, night blindness) is inadequate dietary vitamin A, defined by serum retinol below 0.70 µmol/L; it affects about 190 million preschool children and is a leading preventable cause of childhood blindness.

Vitamin B12

Vitamin B12 (cobalamin) is a water-soluble vitamin from animal foods needed for DNA synthesis, red blood cells, and the nervous system; deficiency causes megaloblastic anemia and neurological damage, treatable orally or by injection.