Non-infectious disease - Prevention Flashcards
Types of hearing loss - conductive
occurs when sound waves cannot reach the inner ear (problem with the mechanical conduction of vibrations); it is caused by defects in the middle or outer ear (perforated eardrum, infections in the middle/outer ear, damage to ossicles and hardening of stapes bone.
Types of hearing loss - sensorinerual
occurs because of damage to, or malformation of the inner ear, including parts of the cochlea, the hair cells or auditory nerve. The most common cause is excessive noise exposure, while others are hereditary, infections, ageing and more.
Most common type of visual disorder - refractive errors
when the eye doesn’t focus light properly due to incorrect shaping of cornea.
Myopia (short-sightedness) - light focusses in front of retina and is caused by eyeball being longer than usual or cornea being curved too steeply.
Hyperopia (long-sightedness) - light focuses behind retina and caused by eyeball being shorter than normal or cornea being curved too little.
other visual disorders
o Cataract – Clouding of the lens reducing transmission of light and resulting in blurry vision.
o Macular degeneration – Deterioration of cells in the retina, resulting in loss of central vision.
function of kidneys
main function of removing nitrogenous wastes from the bloodstream and maintenance of optimal levels of substances such as salt and water (osmoregulation). The kidney has three main functions: filtration, reabsorption and secretion.
hearing loss - cochlear implants
use an external speech processor and transmitter coil and bypass the outer and middle ear and deliver the sound or vibrations directly to the auditory nerve. Internally a receiver is attached to an electrode array surgically implanted in the cochlea. The microphone of the speech processor detects sound, converts it into a digital signal and send it to the transmitter, then receiver. The signals are then converted to electrical signals that are sent to the electrode array in the cochlea to then be sent to the brain.
- Used by people with profound sensorineural loss when hearing aids are not beneficial.
Bone conduction implants
Bone conduction implants have a microphone that detects sound and transforms it into vibrations, that are then passed via the implant to the bone above the ear. These vibrations travel through the bone to cochlea which functions as normal.
- Used to treat conductive or mixed hearing loss or-single sided deafness
Hearing aids
Hearing aids are used to magnify the sound vibrations to better enable their transmission into the middle and then inner ear. They are a small electronic device, consisting of a microphone, amplifier and a speaker.
- Used to improve hearing in people with sensorineural hearing loss.
Glasses or contact lenses
- Glasses contain different types of lenses that allow the eye to focus light on the right part of the retina. Some can provide a level of magnification as well.
- Similarly, contact lenses are a thin, curved lens placed on the film of tears that covers the surface of your eye and corrects the angle of refraction of light so it focuses correctly on the retina.
Intraocular lens implant (cataract surgery)
An intraocular lens (IOL) is placed inside the eye and are artificial lenses made from plastic that work in the same way as a natural lens, however, is a permanent surgical implant. The cloudy lens (usually caused by cataract) is removed from the lens capsule and an artificial lens is inserted, resulting in correct focus and clear vision.
