anatomy - the eye and vision

refraction

light bending

accomodation

ability to focus for close vision (under 20 ft)

emmetropia

normal vision, eye focuses correctly on the retina

hyperopia

inability to focus well on close objects (farsightedness), results from an eyeball that is too short or from a “lazy lens”

photopupillary reflex

reflect constriction of pupils when they are exposed to bright light

cataract

clouding of the lens, resulting in loss of sight

myopia

nearsightedness, distant objects appear blurry, results from an eyeball that is too long, a lens that is too strong, or a cornea that is too curved

astigmatism

blurred vision, resulting from unequal curvatures of the lens or cornea

glaucoma

condition of increasing pressure inside the eye, resulting from blocked drainage of aqueous

convergence

medial movement of the eyes during focusing on close objects

accomodation pupillary reflex

reflex constriction of the pupils when viewing close objects

night blindness

inability to see well in the dark, often a result of vitamin A deficiency

cillary zonule

attaches the lens to the cilliary body

aqueous humor

fluid that provides nutrients to the lens and cornea

sclera

the white of the eye, white connective tissue

optic disk

area of retina that lacks photoreceptor, where optic nerve leaves the eyeball

cilliary body

contains smooth muscle that controls the shape of the lens

choroid

nutritive (vascular) tunic of the eye, heavily pigmented tunic that prevents light scattering within the eye

canal of schlemm

drains the aqueous humor of the eye

retina

contains the rods and cones, contains millions of photoreceptors

vitreous humor

gel like substance behind the lens that helps to reinforce the eyeball

iris

smooth muscle structures (intrinsic eye muscles), pigmented “diaphragm” of the eye

fovea centralis

area of acute or discriminatory vision, area on retina with the highest density of cones

cornea

anteriormost part of the sclera, allows light to pass through, transparent

1. three

2. blue

3. red

4. green

5. at the same time

6. color blindness

7. males

8. rods

1. There are (1) varieties of cones. One type responds most vigorously to (2) light, another to (3) light, and still another to (4) light. The ability to see intermediate colors such as purple results from the fact that more than one cone type is being simulated (5). Lack of all color receptors results in (6). because this condition is sex linked, it occurs more commonly in (7). Black and white, or dim light, vision is a function of the (8)

1. cilliary body

2. cilliary zonule

3. iris

4. aqueous humor

5. lens

6. cornea

7. vitreous humor

8. optic disk

9. fovea centralis

10. sclera

11. choroid

12. retina