Basic Ocular Anatomy

Question 1

What is the main function of the eye?

Answer 1

take information from the environment (light) & interpret it into a neural signal (sight)

Question 2

“Coats” of the eye

Answer 2

1. outer fibrous layer: has cornea & sclera
2. middle vascular layer “uvea”: iris, ciliary body, choroid
3. inner neural layer: retina

Question 3

the cornea layers

Answer 3

outer to inner:
1. epithelium
2. Bowman’s layer (membrane)
3. stroma
4. Descemet’s membrane
5. endothelium

Question 4

cornea functions

Answer 4

function: most important refractive medium in the eye

Question 5

cornea structure

Answer 5

avascular, transparent
due to the spacing of collagen fibrils in the stroma & endothelial cells limiting fluid uptake

Question 6

sclera function

Answer 6

protection, shape, and EOM insertion

Question 7

sclera structure

Answer 7

dense CT layer lined by a thin mucous membrane (conjunctiva)

opaque due to irregularly-space collagen fibrils

Question 8

anterior chamber normal vs abnormal

Answer 8

normal: filled w/ aqueous humor, appears optically empty and black

abnormal: presence of inflammatory cells or increased protein content

Question 9

iris & pupil

Answer 9

thin, contractile, pigmented diaphragm w/ a central aperture (the pupil)

control the amount of light entering the eye

suspended in the aqueous humor

Question 10

pupil movements

Answer 10

miosis (constriction): in bright light & accommodation, response to parasympathetic activity

mydriasis (dilation): low light & during excitement/fear, response to sympathetic activity

Question 11

3 spaces of the eye

Answer 11

anterior chamber & posterior chamber make up anterior segment

vitreous chamber make up posterior segment

Question 12

Lens function

Answer 12

transparent, biconvex structure, grows throughout life

behind the iris and in front of the vitreous body within the posterior chamber

Question 13

lens structure

Answer 13

1. elastic capsule: envelopes the entire lens
2. lens epithelium: anterior surface only
3. lens fibers: main mass of the lens

Question 14

ciliary body function

Answer 14

suspension of the lens and process of accommodation & produces aqueous humor

Question 15

ciliary body structure

Answer 15

complete ring around the lens, continuous w/ choroid posteriorly & peripheral iris anteriorly

Question 16

features of ciliary body & lens

Answer 16

suspension: zonules hold the lens in place
accommodation: an increase in refractive power of the eye through a change in lens shape (ciliary muscle contraction)
Presbyopia: w/ age, lens becomes less elastic, resulting in less accommodation

Question 17

accommodation near vs distance

Answer 17

unaccommodated for distance, ciliary body is relaxed
accommodated for near, ciliary body contracts

Question 18

vitreous body structure

Answer 18

gel-like substance filling the eyeball between the lens and the retina

Question 19

vitreous body functions

Answer 19

1. transmits light
2. retinal metabolism
3. posterior support (shock absorber)

Question 20

Choroid structure

Answer 20

highly vascular and pigmented layer, lining along the inner surface of the sclera

Question 21

choroid functions

Answer 21

nourish the outer layers of the retina and absorbs excess light

Question 22

retina structure

Answer 22

nervous coat, internal layer of the eyeball, thin and transparent membrane

Question 23

retina function

Answer 23

where optical image is formed from focused light, photochemical transduction, and nerve impulses are created and transmitted along visual pathways to the brain

Question 24

macula/fovea structure

Answer 24

oval, darkened area of the central retina

Question 25

fovea centralis

Answer 25

is a depressed area within the center of the macula
- has the highest conc. of cones
-provides the most distinct vision

Question 26

optic nerve/optic disc

Answer 26

site where axons of retinal nerve cells accumulate to exit the eye (opening in sclera)
site where retinal blood vessels enter the eye