Pathophysiology
Clinical meaning
Aging produces predictable changes across sensory systems. Vision: presbyopia (decreased lens elasticity after age 40), cataracts (lens opacification), macular degeneration (central vision loss), glaucoma (optic nerve damage from increased IOP), senile miosis (smaller pupils), lens yellowing (difficulty with blues/greens). Hearing: presbycusis (progressive bilateral high-frequency sensorineural hearing loss), cerumen impaction. Taste/smell: decreased taste buds and olfactory receptors reduce appetite and ability to detect hazards (spoiled food, gas leaks). Touch: decreased Meissner and Pacinian corpuscles increase burn and pressure injury risk. Proprioception: decreased joint position sense increases fall risk. Pain: variable changes — some elderly have decreased perception, leading to silent MI or delayed recognition of peritonitis.