Gross Anatomy of Eye

Question 1

Normal adult has an eye diameter of what?

Answer 1

24-25mm

Question 2

What is the average distance of the eye medial to the bony orbit?

Answer 2

5-7mm

Question 3

Which lid moves more upon closing?

Answer 3

Upper

Question 4

The three layers of the eye are what?

Answer 4

1. Fibrous tunic (cornea and sclera, outermost and strongest)
2. Vascular Tunic (Iris, ciliary body and choroid, middle also called Uvea)
3. Neural tunic (retina, inner most)

Question 5

As the iris moves posterior what happens?

Answer 5

it becomes thinner becomes ciliary body/processes then becomes the choroid

Question 6

Anterior chamber includes what? Posterior? Vitreous?

Answer 6

Everything in front of Iris
Everything behind Iris
Entire eye
(dont get confused with anterior segment: everything in front of vitreous and posterior segment everything behind and including vitreous).

Question 7

What is the main refracting structure? what does the rest? changes in shape/size of eye due to which structure?

Answer 7

cornea (80%), lens.

Sclera.

Question 8

Collarette is what?

Answer 8

Ring of muscle around Iris

Question 9

The average eye is how long across? vertical distance? and circumference?

Answer 9

Across: 12 mm
Down: 11 mm
Circumference: 37 mm

Question 10

Ciliary body is made up of what two structures?

Answer 10

pars plicata: tissue folds (also called ciliary processes around 80 of them)
Pars plana: no tissue folds

Question 11

Ora Serrata is what?

Answer 11

transition zone between anterior uvea and posterior uvea

Question 12

The rounded edges of the pars plana are called? the indentations are called? what do these make up?

Answer 12

Oral bay, deutate process makes up ora serrata.

Question 13

The three layers of the choroid are?

Answer 13

1. Choriocapillaris: tiny holes for capillaries, right next to RPE
2. Sattlers Layer (stromal): small/medium blood vessels
3. Haller’s Layer (suprachoroid): contains large blood vessels

Question 14

Is the choroid pigmented? is it vascular? it is a blood supply for what tissue?

Answer 14

yes, dark brown.
yes
retina

Question 15

What are the three chambers?

Answer 15

1. Anterior: 200ul
2. Posterior: 50ul (smallest one)
3. Vitreous

Question 16

What structures line the anterior chamber? posterior chamber? Vitreous?

Answer 16

Ant: Anteriorly, cornea and posteriorly, anterior iris
Post: anteriorly, posterior iris. Posteriorly, anterior lens and zonules. laterally: junction between iris and ciliary body.
Vitreous: anteriorly, lens and ciliary process. Posteriorly, retina (back of eye)

Question 17

Zonule fibres connect to what?

Answer 17

connects lens to ciliary processes (pars plana)

Question 18

Pathway of trabecular meshwork? which fluid takes this route?

Answer 18

series of small canals, goes to schlemms canal and then to venous system.
Aqeuos humor

Question 19

What are three transparent tissues?

Answer 19

Cornea, lens and vitreous

Question 20

the viscoelastic gel present in vitreous humor is what percent water? what is the refractive index? what are the two zones in the vitreous? what type of cells are found here?

Answer 20

98%. n=1.33
Cortical zone: outer most, denser collagen fibres
Central zone: more liquid
hyalocytes (thought to be macros)

Question 21

Where do the zonules attach to the lens? they are in what shape?

Answer 21

anteriorly, posterioly and centrally.

a ring

Question 22

What happens when ciliary muscles contract?

Answer 22

releases tension on zonules which icnreases curvature of lens increasing dioptic power.

Question 23

Define presbyopia. you wont get this if you are what?

Answer 23

reduced accommodative ability happens around 40-50 years old, loss of elasticity, corrected with + lens.
myopic

Question 24

The viscosity in the vitreous humor is due to what?

Answer 24

sodium hyaluronate and collagen type 11