Ophthalmoscopy

Question 1

What is the cornea?

Answer 1

0.5mm thick

main refractive structure of the eye (40 diopters)

Question 2

What makes up the cornea? How is transparency maintained?

Answer 2

5 distinct endothelial layers and an endothelial layer the maintains hydration

cell orientation and lack of vessels

Question 3

What is the conjunctiva?

Answer 3

Translucent mucous membrane that starts at the limbus and covers the sclera and internal surface of the lids

Contains mucin secreting goblet cells

Question 4

What is the sclera?

Answer 4

Irregular hydrated collagen fibres that form a 1mm thick opaque layer which is covered by highly vascular episclera

The posterior sclera foramen transmits the ON and central retinal vessels

Question 5

What make up the two layers of the iris?

Answer 5

Stroma

Pigment epithelium

Question 6

What is the stroma?

Answer 6

Thin avascular layer which contains the sphincter papillae muscle and determines the iris colour

Question 7

what is the pigment epithelium?

Answer 7

Contains the majority of the iris pigment and contains the dilator pupillae muscle

Question 8

What is the lens held by?

What produces lens fibres?

Answer 8

Held by zonules

Epithelium produces lens fibres throughout life
High protein content. gets affected by cataract formation

Question 9

Where does the lens get its nutrition and oxygen from?

Answer 9

aqueous

Question 10

What is the function of the ciliary body?

Answer 10

o Aqueous secretion
o Accomodation
o Influences aqueous outflow

Question 11

What is the vitreous?

Answer 11

a transparent gel which is firmly attached to the optic disc and pars plana

Contains thick collagen fibres and 99% water. Its function is unknown and has a higher rate of degeneration with age

Question 12

What are the two parts of the retina?

Answer 12

Macula

peripheries

Question 13

What is the function of the macular region?

Answer 13

Provides colour vision (cones) and the fovea lies at the centre of the macula

Question 14

What is the function of the peripheral retina?

Answer 14

Provides side/night vision

Question 15

What is the neural retina responsible for?

Answer 15

Generation, amplification and transport of electrical signals + provides functional and metabolic support for the photoreceptors

Question 16

What is the fovea?

Answer 16

1.5mm diameter depression - region with the highest concentration of cones

Question 17

What is the choroid?

Answer 17

part of uveal tract and is a vascular sheet between the retina and sclera - 0.25mm thick and contains an extensive network of fenestrated vessels.

Question 18

What is the function of the choroid?

Answer 18

Provides the blood supply to the outer retina and is separated from the retina by Bruch’s membrane

Question 19

What is the optic nerve formed by?

What is its function?

Answer 19

Formed by 1 million ganglion cell axons and has a central clearing (cup) which is an empty space – it contains the central retinal vessels and the nerve is myelinated posterior to the sclera – it is covered by an extension of the dural sheath from the brain

Question 20

What things need to be checked on ophthalmoscopy?

Answer 20

Red reflex
Fundoscopy:
1. Optic nerve head (optic disc) - NASAL side
2. Retinal arterioles. Arteries = thinner than veins
3. Retinal venules
4. Macula (dark bit)

Question 21

What is the cause of homonymous hemianopia?

Answer 21

due to contralateral lesions of optic tract or lateral geniculate body

Question 22

What is the cause of a superior quadrantanopia?

Answer 22

Temporal lobe lesion

Question 23

What is the cause of an inferior quadrantanopia?

Answer 23

Parietal lobe lesion

Question 24

What is the cause of a bitemporal hemianopia?

Answer 24

lesion at optic chiasm

Question 25

What is the cause of a bitemporal superior quadrantanopia?

Answer 25

pressure from below the chasm - commonly pituitary tumour

Question 26

What is the cause of a bitemporal inferior quadrantanopia?

Answer 26

Pressure from above the chasm - e.g. craniopharyngioma, meningioma, carotid aneurysm

Question 27

What is an arcuate scotoma? When might it occur

Answer 27

arcuate scotoma: an arc-shaped defect of vision arising in an area near the blind spot and extending toward it May occur in glaucoma

Question 28

What causes peripheral field constriction?

Answer 28

Glaucoma retinitis pigmentosa poison bilateral occipital lobe infarcts, hysteria

Question 29

What muscle supplies the superior oblique?

Answer 29

CN IV (trochlear)

Question 30

What muscle supplies the inferior oblique?

Answer 30

CN III (oculomotor)

Question 31

What muscle supplies the superior rectus?

Answer 31

CNIII

Question 32

What muscle supplies the inferior rectus?

Answer 32

CNIII

Question 33

What muscle supplies the medial rectus?

Answer 33

CNIII

Question 34

What muscle supplies the lateral rectus?

Answer 34

CN VI

Question 35

What muscle supplies the levator palpebrae superiors?

Answer 35

CNIII

Question 36

Where do the recti originate from?

Answer 36

common tendinous ring in the posterior part of the orbit