The globe

Question 1

What proportion of the globe does the anterior segment form?

Answer 1

1/6th

Question 2

What is the radius of curvature of the AC?

Answer 2

roughly 8mm

Question 3

What proportion of the globe does the posterior segment form?

Answer 3

5/6th

Question 4

What is the radius of the posterior segment?

Answer 4

12mm

Question 5

Where does the posterior pole lie in relation to the optic nerve head?

Answer 5

slightly temporally

Question 6

Which anatomical landmark forms the anterior pole?

Answer 6

centre of curvature of the cornea

Question 7

Which anatomical landmark forms the posterior pole?

Answer 7

centre of posterior curvature of the eyeball

Question 8

What is the optical axis?

Answer 8

the line connecting the anterior and posterior poles

Also known as geometric axis

Question 9

Where does the equator lie?

Answer 9

Halfway between anterior and posterior poles

Question 10

What is the visual axis

Answer 10

line connecting the fovea centrals of the retina with the nodal point of the eye and continuing anteriorly through the cornea

Question 11

Do the optic axis and the visual axis coincide?

Answer 11

NO.
fovea is temporal and slightly inferior to the posterior pole, so optical and visual axes do not coincide

Question 12

What are the lengths of the following diameters:
a) the anteroposterior diameter of the eye
b) vertical diameter of the eye
c) horizontal diameter of the eye

Answer 12

a) 24mm
b) 23mm
c) 23.5mm

Question 13

Is a patient more myopic of hypermetropic if the AP diameter of the eye is longer?

Answer 13

MYOPIC

Question 14

Where in the orbital cavity is the eyeball found?

Answer 14

Anterior part, closer to the roof than the floor. Closer to lateral wall than medial wall

Question 15

If a line is drawn from the superior to inferior orbital margin, what will it coincide with?

Answer 15

Cornea/slightly anterior to it

Question 16

if a line is drawn from medial to lateral orbital rim, what proportion of the eye lies infant of it?

Answer 16

1/3rd

Question 17

How far from the limbus do the following muscles insert into the sclera:
a) medial rectus
b) inferior rectus
c) lateral rectus
d) superior rectus

Answer 17

a) 5.5mm
b) 6.5mm
c) 6.9mm
d) 7.7mm

Question 18

How far from the limbus does the medial rectus insert into the sclera?

Answer 18

5.5mm

Question 19

How far from the limbus does the inferior rectus insert into the sclera?

Answer 19

6.5mm

Question 20

How far from the limbus does the lateral rectus insert into the sclera?

Answer 20

6.9mm

Question 21

How far from the limbus does the superior rectus insert into the sclera?

Answer 21

7.7mm

Question 22

The volume of the globe is:
a) 15ml
b) 3 ml
c) 6.5ml
d) 12ml

Answer 22

c) 6.5ml