Eyes Flashcards
Rods and cones
Cones>.colours»and are spaced near the FOVEA
Rods»night vision»and are spaced away from the FOVEA
Blind spot is where the optical nerve is connected Pupil >>makes the light in 6 muscles pull the eyes up and down Iris Pupil Lens Cornea
Presbyopia
Presbyphia»age related long sightedness
Saccase»_space;quick simultnanoues mvemnt of both eyes between two
Accomodation
Squishing the eye with the ciliary muscle to change the shape of the eye ball
The vision should be able to see at 20feet that whihc the so called nirmal person is capable of seeing at this range
Visual acuity depends from the angular distance from the FOVEA
140 degrees is the visual vision using both eyes in front,
It can be 180 to the sides just on
Dark to light»10sec
Light to dark» cones 7min, rods 30min
Red light helps to optimise the night vision
Night vision
Looking away 10/15degres helps night vision
Affected by ~age ~mild hypoxia ~cabin altitudes above 5000 ~smoking ~alcohol ~deficiency of vitamin A
Colour vision deficency
Colour visoin deficinecy
Genetic fault
Missing cones
More common in male gender 7% than female 0.1%
Binocolour vision
Depth perception. ,effective up to 200ft/60m
Non stereoscopic vision to figuer out the depth
~colour
~contrast
~size
~rate of movement
Sunglasses should be
Impact ressiteant Thin meatl frames Coated with polycarbonate for strentgh Good optical Don’t use polarised lenses
For high energy blue light and uv rays ,sunglasses can prevent damage to the retina
