Vision Flashcards
What are the roles of the visual system?
Interaction with environment
Anticipatory function - Warning about potential dangers
Social interactions - Non-verbal communication
Motor movement - Eye-hand coordination, postural control
What are zonules?
Ligaments connecting the lens to ciliary body.
What are the functions of the iris?
Eye color
Pupil size
What are the ciliary body?
Ring-shaped structure with lens muscles
What is the cornea?
The entry point of light into the eye
What is the sclera?
Eye white
Provides muscular attachments
What is the choroid?
Vascular membrane that provides collateral blood flow.
What is the macula?
The pigmented area with cones for high acuity.
How do the numbers of rods and cones compare?
There are way more rods (120 milion) than cones (5 million).
How do the rods and cones respond to light?
Rods are very sensitive to light. Cones need enough light to perceive colour.
How do the distributions of rods and cones compare?
Rods are distributed equally over the retina, while cones are concentrated in macula
How many cranial nerves are involved for the movement of eyes?
4
Which cranial nerve innervates the eyelid?
CN III
What are the most common problems with the eye?
Acuity (near/far) Cataracts Macular degeneration Glaucoma Diabetic retinopathy
What is myopia?
Near-sightedness due to eye length being too long.
What is hyperopia?
Far-sightedness due to eye length being too short.
How do acuity issues present?
Blurred, fuzzy vision with decreased ability to focus.
Adjusting distance between self and objects.
Uses peripheral vision.
Needs more light.
Cautious when ambulating.
Which test is often used for acuity?
Snellen letter chart
What are the procedures for Snellen letter chart?
Test eyes separately and together from 6 feet away. 20/20 considered norm.
What are the treatments for acuity issues?
Glasses
Surgery
Laser treatment
What is presbyopia?
Problems with near vision due to degenerative lens thickening starting at over 40 years
Why do women need reading glasses before men?
Men tend to have longer arms, so they can hold things far for longer until they absolutely need glasses.
What are cataracts?
Degenerative clouding of the lens which limits light from entering through the lens. The leading cause of visual impairment.
What are the symptoms of cataracts?
Sensitivity to light Difficulty seeing detail Poor central vision, compensation with peripheral vision (seeing with head turned) Difficulty seeing colours Limited night vision
What are the treatment options for cataracts?
Using higher contrast
Surgery to remove lens and insert artificial lens
What is the success rate of cataract surgeries?
95%
What are the risk factors for cataracts?
Age Family history Diabetes mellitus Smoking Alcohol Sun exposure Medications Injury
What is macular degeneration?
Damage to blood vessels resulting in progressive degeneration of the macula, affecting central vision in one or both eyes.
True or False: Macular degeneration is age-related.
True. It is the leading cause of vision loss in in elderly.
What is the cure for macular degeneration?
There is no cure, only treatments to slow the process.
What is glaucoma?
Damage to the optic nerve, often by build up of fluid causing pressure in the eye.
What is the main symptom of glaucoma?
Loss of peripheral vision, i.e. tunnel vision
Less dynamic vision → Avoidance of dynamic environments
Glaucoma is often [detected/undetected] and [can/cannot] cause complete blindness.
Undetected
Can cause complete blindness