Introduction to anatomy/embryology of the eye

Question 1

Eye embryology:
Optic vesicles reach the surface ectoderm, this stimulates the ectoderm to thicken and form the (a)……………….. This then invaginates to form (b)……………………..

Answer 1

(a) lens placode

(b) optic cup

Question 2

A choroid fissue is formed in the inferior wall as blood vessels pass through, in health this will usually disappear as the eye develops. If it doesn’t disappear a hole can be left in any of the structures of the eye. This is known as…..

Answer 2

Coloboma

Question 3

A break in the retina allows vitreous humor to enter the potential space between layers of the optic cup, causing painless loss of vision

Answer 3

Retinal detachment

Question 4

Direct trauma to orbit causing thin inferior and medial orbital bones fracture causing contents to herniate into nearby sinuses

Answer 4

Blow out fracture (can see “tear drop sign” on a CT scan)

Question 5

Orbital fat (a)………… in thyroid disease leading to (b)…………….

Answer 5

(a) hypertrophies

(b) proctosis

Question 6

Name the blood vessels which supply the cornea

Answer 6

None, the cornea is avascular and is supplied by passive diffusion from surrounding structures

Question 7

……………… of cornea has an active pump to keep aqueous humor out of the stroma

Answer 7

Endothelium layer

Question 8

Healing of damage deeper than the epithelial layer of the cornea will cause:

Answer 8

Scarring which will create an opacity in the cornea and reduce vision

Question 9

Why are corneas viable to be transplanted to any patient

Answer 9

Their avascularity means there is a much lower chance of the donor graft being rejected

Question 10

Which anatomic site is responsible for the physiological blind spot and why?

Answer 10

The optic head, there are no rods/cones in this region

Question 11

Which anatomic site is responsible for maximal visual acuity and for which two reason?

Answer 11

Fovea centralis. It contains only densely packed cones and it has the thinnest layer of ganglional cells of the whole retina

Question 12

Aqueous humor is produced by………

Answer 12

The ciliary body

Question 13

What is the function of aqueous humor

Answer 13

Maintains pressure within the eyeball

Question 14

Aqueous humor flows through the iris and is filtered out at the angle at the edge of the anterior chamber through (a)…………. and into (b)…………… which connects into venous channels. A blockage to this system causes (c)………………

Answer 14

(a) Trabecular meshwork
(b) Schlemm’s canal
(c) Glaucoma