Ophthalmology, Otology, and Aging: Vision, Hearing, and Smell Disorders

Cataracts

Cloudy lens; blurred vision, glare, decreased color vision; treat with lens replacement.

Glaucoma

Chronic pressure above 20 mmHg damaging the optic nerve.

Amblyopia (lazy eye)

Reduced vision not due to physical eye disease.

Scotoma

Blind spot in visual field due to optic nerve or retinal lesion.

Presbyopia

Age-related loss of lens flexibility causing difficulty focusing on near objects.

Myopia

Nearsightedness — can't see far objects.

Hyperopia

Farsightedness — can't see near objects.

Astigmatism

Irregular corneal curvature causes blurry vision.

Color blindness

X-linked condition; can't distinguish red from green.

Hemianopia

Loss of half of visual field.

Papilledema

Swelling of optic disc due to increased intracranial pressure.

External ear

Includes pinna, auditory canal, and eardrum; conducts sound.

Middle ear

Contains malleus, incus, stapes, oval window, and Eustachian tube; transmits sound.

Inner ear

Includes cochlea and semicircular canals; controls hearing and balance.

Organ of Corti

Contains hair cells that convert sound waves to nerve signals.

Otoliths

Calcium crystals that sense movement and position.

Presbycusis

Age-related high-frequency hearing loss due to cochlear hair cell degeneration.

Conductive hearing loss

Sound blocked in outer or middle ear (wax, fluid, infection).

Sensorineural hearing loss

Damage to cochlea or nerve pathways (aging, ototoxic drugs, loud noise).

Mixed hearing loss

Combination of conductive and sensorineural loss.

Functional hearing loss

No physical cause; psychological origin.

Otitis externa

Outer ear infection ("swimmer's ear") from bacteria; causes pain, swelling, drainage.

Otitis media

Middle ear infection, often from bacteria (S. pneumoniae, H. influenzae).

Hyposmia

Reduced ability to smell.

Anosmia

Complete loss of smell.

Olfactory hallucinations

Smelling odors that aren't present (seen in temporal lobe seizures).

Parosmia

Distorted or "off" sense of smell.

Hypogeusia

Decreased taste sensation.

Ageusia

Loss of taste.

Parageusia

Distorted or unpleasant taste.

CN IX damage

Loss of bitter taste.

CN VII damage

Loss of sweet, salty, and sour taste.