Physiology Lab - Vision 2

Question 1

What does ophthalmoscopy (fundoscopy) examine?

Answer 1

Interior of the eye - retinal structures in particular e.g. optic disc, retinal blood vessels and the macula

Question 2

What does the slit lamp examination look at?

Answer 2

Anterior segment of the eye - allows us to visualize the actual anatomy of the anterior segment

Question 3

Describe the principles explaining how ophthalmoscopy works.

Answer 3

Light rays entering the eye through the pupil return along the same path when exiting the eye after reflection.
This can be used in order to view the interior aspect of the eye - we look along a beam of light directed into the pupil.

Question 4

What is the most widely instrument used for ophthalmology?

Answer 4

Monocular direct ophthalmoscope

Question 5

Explain how a monocular direct ophthalmoscope works.

Answer 5

Mirror on to which light from a lamp is focused
Small central hole in the mirror allows the observer to look through
Small and round apertures are used for small and large pupils
Vertical slit is used for gauging elevation of a retinal lesion
Grid can be used to measure size
Green filter provides red-free light beam = identify haemorrhages & to distinguish nerve fibres coursing to the optic nerve

Question 6

What is the first thing to do when starting the ophthalmology exam?

Answer 6

Test red reflex - reflection of light back from the retina

Question 7

What are the 3Cs about the optic disc?

Answer 7

Cup, colour, contour

Question 8

Name the three steps of the ophthalamogy exam.

Answer 8

1 - red reflex
2 - optic disc
3 - macula

Question 9

Name the 4 things the slit lamp allows you to assess.

Answer 9

Three layers of the cornea
The iris
The front and back surface of the lens
The anterior surface of the vitreous

Question 10

Name the five layers of the cornea.

Answer 10

Epithelium
Bowman’s membrane
Stroma
Decemet’s membrane
Endothelium
6th layer = tear film - visible on the front surface of the cornea, glistening layer that moves rapidly upwards following each blink
*** Can only see three layers with slit lamp

Question 11

What is the function of the iris?

Answer 11

Regulates the amount of light entering the eye - alters pupil size

Question 12

Name the two layers making up the iris.

Answer 12

Stroma = group of fibres - dilator/constrictor fibres)

Question 13

How are the dilator vs constrictor fibres of the stroma of the iris arranged?

Answer 13

Dilator fibres in roughly radial pattern

Constrictor fibres is a sphincter around the pupil margin

Question 14

What pigment determines the colour of our eyes?

Answer 14

Pigment along stromal fibres

Question 15

Where does the obstruction of light occur?

Answer 15

In the pigment epithelium of the iris (behind the stroma)

Question 16

What is the lens made up of?

Answer 16

Multi-layered structure made up of the cortex and a nucleus within an elastic capsule

Question 17

Where can the anterior surface of the vitreous be seen?

Answer 17

Very transparent in a young eye

Visible if there is a small gap between it and the posterior surface of the lens

Question 18

Name the aspects of the eye which are examined by the slit lamp.

Answer 18

1 - External (cheek, nose, brow)
2 - Lids and lashes
3 - Conjunctiva and sclera
4 - Cornea 
5 - Anterior chamber (fluid filled space) 
6 - Iris 
7 - Lens
8- Vitreous chamber/cavity