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Technology used to fix eyes - Coggle Diagram
Technology used to fix eyes
Glasses
Myopia = concave lenses
Extends focal length of light rays; allows focused image to fall on retina
Thicker towards outside, thinner in middle
Bend light rays outwards, diverge before they reach the eye
Hyperopia = convex lenses
Bends light rays inwards, converge before they reach the eye
Thicker towards centre, thinner towards edges
Shortens focal length; allows focused image to fall on retina
Laser eye surgery
What is the visual disorder being treated?
Myopia
Hyperopia
Astigmatism
hese disorders can also be managed through the use of glasses and/or contacts. However, Laser eye surgery results in a permanent treatment.
How does the disorder impair visual function?
When the clear front surface of the eye (the cornea) curves too steeply or the eyeball is too long, the light entering the eye does not focus on the back of the eye (retina), but focuses in front of the retina so the image appears blurry. Inversely long sightedness also causes blurry vission due to the cornea being too flat, or the eyeball being too short. This mean the light entering the eye focuses behind the retina instead of on it.
What treatment exists for the visual disorder and how does it work?
The LASIK procedure reshapes the cornea to enable light entering the eye to be properly focused onto the retina for clearer vision. This is accomplished by a surgeon then folds back the hinged flap to access the underlying cornea (called the stroma) and removes some corneal tissue using an excimer laser. Excimer lasers create a cool ultraviolet light beam to remove ("ablate") microscopic amounts of tissue from the cornea to reshape it so light entering the eye focuses more accurately on the retina for improved vision.
How effective is laser surgery?
In general, Laser eye surgery has a very good chance of achieving 20/25 vision or better for a patient after surgery. More than 8 out of 10 people who've undergone LASIK refractive surgery no longer need to use their glasses or contact lenses for most of their activities. However, one study conducted found that 35 percent of individuals who had LASIK needed retreatment over 10 years.
Contact lenses
Shaped to fit the curvature of the eyeball
Lens + refraction of light, similar to spectacles
Smaller + directly in contact with surface
Cataract surgery
Corrects cataracts
Cloudy lens removed from lens capsule
Artificial lens is inserted via small incision
Device inserted, delivers high- frequency sound
Sound breaks up cloudy lens
Small lens particles are suctioned out