Chapter 7- Optometric instrumentation part 2 (1)

Question 1

What are the two types of ophthalmoscopy?

Answer 1

1- Direct ophthalmoscopy

2- Indirect ophthalmoscopy

Question 2

What is direct ophthalmoscopy?

Answer 2

This is a method of examining the external eye, internal eye, and retina

Question 3

Is ophthalmoscopy done on all patients?

Answer 3

Yes

Question 4

By law, what should you perform when conducting an eye test?

Answer 4

You must perform an internal and external examination and carry out additional examinations as appear to be necessary to detect signs of injury, disease, or abnormality in the eye or elsewhere.

Question 5

What is on the front of the direct ophthalmoscope?

Answer 5

A system of filters

Question 6

What is down at the bottom of a direct ophthalmoscope?

Answer 6

A rheostat which controls the brightness

Question 7

What should a practitioner do when doing direct ophthalmoscopy?

Answer 7

Remove their glasses, unless they have a high astigmatism or prescription.

Question 8

What should a patient do when going through direct ophthalmoscopy?

Answer 8

They should remove their glasses.

However, if your patient has a high prescription, the image you’ll see on the ophthalmoscope will be quite disjointed so it’s best for them to keep them on.

Question 9

When looking at the external eye, what power would you need on your lens wheel on the ophthalmoscope?

Answer 9

+12D

Question 10

When you move closer to the patient and go through the eye, what should you do?

Answer 10

Reduce the lens power and examine the iris and anterior chamber.

The Px (patient) looks up, down, left, and right.

Question 11

When examining the crystalline lens, what should you adjust the lens power to?

Answer 11

+8D

Question 12

When looking behind the lens (optic media), what would you do?

Answer 12

You would reduce the plus power more and examine the vitreous (floaters)

Question 13

How would you examine the optic disk?

Answer 13

1- Adjust the lens power to 0D

2- Patient looks straight ahead

3- Examine the optic disc- you do this by looking at the vertical C/D ratio (cup/disk ratio) and check the appearance of the disc margins

Question 14

What is the C/D ratio?

Answer 14

The vertical diameter of the cup expressed as fraction of the vertical diameter of the optic disk. Written in decimal notation.

Question 15

Why do we measure the C/D ratio?

Answer 15

Because this will help give us an indication as to whether a patient has glaucoma.

Question 16

What are the blood vessel colours in the eye?

Answer 16

Arteries= lighter red and thinner

Veins= darker red and thicker

Question 17

What two parts from the ophthalmic artery come into the eye through the optic nerve head?

Answer 17

The central retinal artery and the central retinal vein

Each then branches from the optic nerve head to serve four main quadrants of the retina.

These vessels provide the blood supply for the inner two thirds of the retina.

Question 18

What type of zone is the macula?

Answer 18

The macular is an avascular zone- no blood vessels present and has the fovea at its centre.

Question 19

What are the advantages of direct ophthalmoscopy?

Answer 19

1- The image you see is erect- the right way round

2- Good magnification

3- Portable

4- No eyedrops need to be put in

Question 20

What are the disadvantages of direct ophthalmoscopy?

Answer 20

1- Small field of view

2- 2D image so you can’t tell the depth of anything

3- Difficult with small pupils

Question 21

A panoptic ophthalmoscope is a form of what?

Answer 21

Indirect ophthalmoscopy

Question 22

What are the advantages of a panoptic ophthalmoscope?

Answer 22

1- About 5x greater FoV- field of view

2- Good for amblyopes- someone with a lazy eye

Question 23

What are the disadvantages of a panoptic ophthalmoscope?

Answer 23

1- It is 2D

2- Not superior to the direct ophthalmoscope for detecting diabetic retinopathy.

Question 24

What is indirect ophthalmoscopy (volk lens)?

Answer 24

Uses a positive lens to form an aerial image which is real and inverted with a magnification of x2 and x5.

Question 25

To perform volk, what do you need?

Answer 25

A slit lamp