1,240 articles
Computer vision syndrome
Computer vision syndrome, or digital eye strain, is a group of eye, vision, and musculoskeletal symptoms from prolonged screen use, affecting about 69% of users, driven by reduced blinking and accommodative fatigue, and managed mainly with ergonomics and breaks.
Concussion
Concussion, a mild traumatic brain injury from head trauma causing temporary altered mental status; also commotion cerebri. Key facts: 300,000 US sports cases yearly, 24-48h rest then early return to school, 6-step return-to-play, Amsterdam 2022 SCAT6 tools.
Concussions in American football
Concussions in American football: sport-related traumatic brain injuries in a collision sport. NFL protocol since 2011, highest football impact accelerations (83.2 g), youth incidence 1.41 per 1,000 exposures, CTE link, $1 billion settlement, Guardian Caps and kickoff rule changes.
Conductive hearing loss
Conductive hearing loss (CHL): hearing loss from blocked or faulty sound transmission in the outer or middle ear, with normal bone conduction; causes include earwax, otitis media, perforation, otosclerosis; often treatable.
Cone cell
Cone cell (cone photoreceptor): retinal photoreceptor for daylight and color vision, with S, M, and L opsins peaking at 420, 534, and 564 nm; less sensitive than rods, never saturates, adapts in minutes.
Cone rod dystrophy
Cone rod dystrophy (CORD, CRD) is a group of inherited retinal diseases in which cone photoreceptors degenerate first, then rods, causing childhood-onset vision loss, photophobia, and legal blindness by mid-adulthood; over 30 genes, chiefly ABCA4, GUCY2D, CRX, and RPGR, are implicated.
Congenital cervical spinal stenosis
Congenital cervical spinal stenosis (ORPHA:831, congenital narrowing of cervical spinal canal, ICD-10 Q06.8) is a rare neurological disease with cervical canal sagittal diameter under 14 mm, predisposing to myelopathy and trauma-induced cord injury.
Congenital cornea plana
Congenital cornea plana (cornea plana congenita, CNA1/CNA2) is a rare bilateral flattening of the cornea causing high hyperopia; recessive CNA2 stems from KERA (keratocan) mutations, dominant CNA1 is milder and genetically unexplained.
Congenital hearing loss
Congenital hearing loss is deafness present at birth, about half genetic and half environmental; congenital CMV is the leading nongenetic cause, detected through universal newborn hearing screening.
Congenital primary aphakia
Congenital primary aphakia (CPAK, OMIM 610256) is a rare birth defect in which the eye's lens never forms, caused mainly by autosomal recessive FOXE3 variants, with anterior segment aplasia, microphthalmia, and glaucoma.
Conjunctiva
Conjunctiva (tunica conjunctiva): transparent mucous membrane lining the eyelids and covering the sclera except the cornea; secretes tear mucus, guards against infection; affected by conjunctivitis and subconjunctival hemorrhage.
Conjunctival scars
Conjunctival scars are permanent fibrous changes in the conjunctiva, the membrane covering the eye; with chronic inflammation the condition is cicatrizing conjunctivitis, with incidence about 1.3-1.5 per million.
Conjunctival vascular disorders
Conjunctival vascular disorders (ICD-11 9A61.4; conjunctival vascular disease) are disorders of conjunctival blood vessels, covering hyperemia, subconjunctival hemorrhage, and vascular tumors and malformations such as lymphangioma and hemangioma.
Conjunctivitis
Conjunctivitis (pink eye) is inflammation of the conjunctiva causing red, discharging eyes; mainly viral (~80% of infectious cases), bacterial, or allergic; contagious viral and bacterial forms usually self-resolve.
Conjunctivochalasis
Conjunctivochalasis (CCH), also called conjunctival chalasis, is a loose, redundant folding of the bulbar conjunctiva, typically bilateral and inferior, mainly from aging, causing tear film instability, irritation, and epiphora; treated with lubricants, anti-inflammatories, or conjunctival excision or cauterization.
Connectome
Connectome: the complete map of neural connections in a nervous system, coined by Sporns and Hagmann in 2005. Studied at micro, meso, and macroscales via tractography and fMRI; central to the Human Connectome Project.
Connectomics
Connectomics: neuroscience field mapping complete neural wiring diagrams (connectomes), coined 2005 by Sporns and Hagmann; spans dMRI tractography in humans, EM datasets like FlyWire (139,255 fly neurons) and MICrONS, and the Human Connectome Project.
Consciousness
Consciousness, also called subjective or phenomenal experience, is the presence of first-person experience; studied via global workspace, IIT, and higher-order theories, with neural correlates and clinical disorders of consciousness.
Constrained spherical deconvolution
Constrained spherical deconvolution (CSD) is a diffusion MRI method introduced in 2007 that estimates fiber orientation distributions in the brain, using a non-negativity constraint and implemented in MRtrix3.
Consumer neurotechnology industry
The consumer neurotechnology industry sells non-implanted, non-clinical devices, mostly wireless EEG headsets and headphones, for sleep tracking, meditation, focus monitoring, and gaming, sold as consumer electronics rather than medical devices.
Contact lens
Contact lens: thin corrective, cosmetic, or smart lens worn on the eye; soft and RGP types; first corrective lenses 1888 (Fick, Kalt), hydrogel 1959, disposables 1982, silicone hydrogel 1999; over 140 million wearers.
Contact lens-associated corneal infiltrates
Contact lens-associated corneal infiltrates, also called corneal infiltrative events, are white inflammatory cell aggregates in the cornea of lens wearers; distinguishing sterile infiltrates from microbial keratitis drives urgent management.
Contracted socket
Contracted socket (eye), also called socket contracture after enucleation or evisceration: shrinkage of anophthalmic orbital tissue with shallow fornices that prevents retention of an ocular prosthesis; graded by severity and treated with grafts, implants, and flaps.
Contrast (vision)
Contrast in vision is the difference in lightness or darkness between an object and its background; contrast sensitivity testing can detect eye diseases that standard acuity measurement misses.
Conus medullaris
Conus medullaris: the cone-shaped tapered end of the spinal cord, terminating around L1 (range T12-L3) in adults. Key facts: embryonic ascent, tethered cord thresholds, lumbar puncture safety, conus medullaris syndrome.
Cornea
Cornea: transparent front tissue of the eye, major refractive element; five layers including non-regenerating endothelium; site of keratoplasty, first performed by Zirm in 1905, now supplemented by endothelial cell therapy.
Corneal abrasion
Corneal abrasion, a scratch of the corneal epithelium, is a common eye injury from trauma, foreign bodies, or contact lenses. Diagnosed with fluorescein and slit lamp; heals in 1-3 days; patching not recommended and antibiotic benefit unproven.
Corneal abscess
Corneal abscess, a suppurative form of infectious keratitis appearing as a white corneal opacity, caused by bacteria, fungi, or parasites; diagnosed by corneal scraping or suture sampling, treated with fortified topical antibiotics and sometimes keratoplasty.
Corneal deformities
Corneal deformities (ICD-11 9A78.5) are abnormal corneal shapes, chiefly keratoconus (9A78.50) and corneal staphyloma (9A78.51), causing blurred vision and irregular astigmatism, treated with lenses or keratoplasty.
Corneal degeneration
Corneal degeneration (ICD-10 H18.4, ICD-11 9A78.4) covers acquired corneal changes from aging, metabolism, or inflammation, unlike hereditary dystrophies; examples include arcus senilis, band keratopathy, and Salzmann nodular degeneration.