AVPS - Opthalmoscopy II - Topic 5

Question 1

What is the red free filter?

Answer 1

Blocks red light.

Question 2

What are the functions of the red-free filter?

Answer 2

• Enhances visibility of retinal blood. vessels/haemorrhages

* Can also help in C:D ratio assessment (see later) and to identify nerve fibre layer (NFL) dropout, a sign of glaucoma

Question 3

What is the Blue filter?

Answer 3

Used in fluorescein angiography, an imaging technique used particularly in patients with diabetes/AMD

Question 4

What is the function of the blue filter?

Answer 4

Can enhance reflectivity of optic disc drusen

Question 5

What is the Graticule, on the aperture wheel, used for?

Answer 5

• Used to determine relative size and position of fundus features.
• Can also be used in assessment of eccentric fixation/steadiness of fixation

Question 6

What is the Slit, on the aperture wheel, used for?

Answer 6

•Helps assess the depth of structures.

Question 7

What is the fundus of the eye?

Answer 7

is the inside, back surface of the eye. It is made up of the retina, macula, optic disc, fovea and blood vessels.

Question 8

What is the systematic examination for Posterior Eye examination?

Answer 8

1. Media.
2. Optic Nerve Head.
3. Vascular Arcades/Blood Vessels.
4. Peripheral Retina.
5. Macula.

Question 9

What are the advantages of using opthalmoscope for posterior eye examination?

Answer 9

◦Portable/hand-held – can be used for domiciliary visits.

◦Relatively simple to perform.◦Useful when slit lamp cannot be used.

◦Image degradation can give an idea of visual dysfunction for patient caused by cataract.
◦Direct view so retina appears in actual orientation – image is erect, non-reversed.
◦Moderate to high magnification for posterior eye examination(15x for an emmetrope).
◦Can use lens rack power as estimate of spherical refractive error

Question 10

What are the limitations of using Opthalmoscope for examining posterior eye?

Answer 10

◦Monocular view – no stereopsis, i.e. hard to assess depth.
◦Small FOV (approx. 5°) – may require pupil dilation for adequate view.
◦Poor view through media opacities, e.g. cataract.
◦Short working distance – can be uncomfortable for patient and practitioner.
◦Patient’s refractive error can have a big effect on magnification/FOV – high myopes -> high magnification, small FOV and vice versa.
◦Poor for viewing anterior eye – other methods should be used unless absolutely no choice.
◦Can lead to back/strain problems over longer term.
◦Difficult to assess changes in colour.
◦Can’t see very far into the periphery (can’t see past equator).
◦Time consuming/difficult to assess entire fundus in detail

Question 11

Why do we use the largest beam if possible?

Answer 11

– more light = easier to view structures

Question 12

What is emmetropia?

Answer 12

• term used to describe a person’s vision when absolutely no refractive error or de-focus exists.
• Your vision is normal and you can see clearly at all distances and do not require glasses.

Question 13

For macula, what aperture do you use on the opthalmoscope?

Answer 13

Small aperture

Question 14

For the general posterior eye, which aperture do you use for the opthalmoscope?

Answer 14

Use medium aperture

Question 15

What is the function of the lens rack?

Answer 15

• Will alter refraction of light rays

- Will make light focus on both retina’s