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OD1 Semester 2 - Integrated Ophthalmic Sciences and Preclinical Optometry > Direct and MIO - Week 1 > Flashcards

Direct and MIO - Week 1 Flashcards

1
Q

Compare Direct and MIO for the following:

  • Image of Fundus (IOF)
  • Image orientation (IO)
  • Stereopsis
  • Field of View (FOV)
  • Magnification
  • Limitation
A 
Direct.           MIO
IOF:        Virtual           Real
IO:          Upright.        Upright
Stereo:     No.                No 
FOV:       5deg(2DD).  12deg(4DD)
Mag:         15x.                5x 
Lim:        Equator.        Beyond Equator
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2
Q

What are the different clinical uses for an opthalmoscope?

A
  • visualisation and localisation of opacities
  • examination of vitreous and posterior pole
  • examination of mid-peripheral retina
  • assessment of fixation
  • corneal or conjunctival defect/lesion (cobalt blue filter)
  • PD + pupils testing
  • Oreos Make Very Filling Cake Pastry
  • opacities, mid-periph, ret., fixation, conjunctival, pupils
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3
Q

What aperture size do we generally use in preclin (for opthalmoscopy)?

A

The middle aperture

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4
Q

What aperture size is used for pupils/PD? (Dilated)

A

Large aperture

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5
Q

What aperture size is used for viewing the macula with opthalmascope?

A

Small aperture

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6
Q

What 3 controls do all modern opthalmoscopes have?

A
  1. On/off switch – also controls brightness of light. is usually found on the top of the handle
  2. Focus - adjusted by lens wheel (found on size of head of instrument, has a range of lens powers)
  3. Aperture of the light – for keeler it’s that switch on the back (for Heine it’s a dial on the front - because its precision german engineered and the superior ophthalmoscope)
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7
Q

How do you adjust focus for opthalmoscope?

A
  • adjusted by lens wheel on the side
    Dialing clockwise: Increases the lens power
    Dialing counter-clockwise: Decreases the lens power
  • note: clockwise means downwards if opthalmoscope is upright

Adjusting lens power will move the focal point

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8
Q

What influences your choice of aperture?

A

What you are looking at
The pupil size
The region you are looking at

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9
Q

What’s the purpose of the slit beam?

A
  • it highlights contours/indicates depth

- it is a source of indirect illumination

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10
Q

Why are glasses best removed from the px during ophthalmoscopy? Are there any cases where it’s better to leave them on?

A
  • glasses often produce reflections and artifacts, and can be physically awkward during the examination

However, if they have a high Rx, it may be better to leave them on – b/c the ophthalmic lenses alone may not be powerful enough to neutralise a high refractive error

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11
Q

When looking through an ophthalmascope, which eye should we use?

A

Right eye for px right eye

Left eye for px left eye

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12
Q

What is the “red reflex” that you see when looking at a px’s eyes through an ophthalmoscope?

A

It is the reflection of the ophthalmocope light off the choroidal vessels

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13
Q

True or False: Viewing the red reflex is useful for determining the clarity of the ocular media?

A

True

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14
Q

What happens to the red reflex if there is a very dense opacity?

A

The red reflex disappears

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15
Q

What’s the primary first goal when looking through an opthalmoscope to a px’s eye?

A

To find the optic disc – use it as a reference point

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16
Q

What makes a Red-free filter?

A

A monochromatic green source light

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17
Q

Advantages of a Red-free filter?

A
  • Increased vessel detail – red free light gives a better contrast b/w retinal vessels and the underlying background; easier to see vessels
  • Easier to see nerve fibre layer (visualisation of NFL)
  • Differentiate pigment/naevus from blood
  • localisation of pigmentary lesions
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18
Q

Why is visualisation of the NFL (nerve fibre layer) important?

A

NFL loss could indicate gluacoma or optic nerve disease –> shown via the loss of the usual “stripey” look to the NFL

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19
Q

What happens to choroidal naevus, retinal naevus and blood when using red-free filter?

A

Choroidal naevus: disappears
Retinal naevus: stays the same
Blood: looks darker (than pigment)

(note: a naevus is basically just a pigmentation

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20
Q

How does refractive error of px influence the size of the fundus image in ophthalmoscopy?

A

Myopic patient: image appears slightly larger

Hyperopic patient: image appears slightly smaller

21
Q

What are the potential problems that can occur with direct ophthalmoscopy?

A
  1. Unable to focus fundus image
  2. Insufficient FOV
  3. Unable to visualise fundus
  4. Unable to visualise macula
  5. Excessive reflections
22
Q

How can you resolve an uncorrected high rx? (for ophthalmoscopy problem)

A
  • use auxillary lenses

- view through patients rx (even though you’ll get increased reflections and decreased FOV it may still be worth it)

23
Q

How to resolve uncorrected astig for ophthalm?

A
  • view through rx
24
Q

What could cause difficulty focusing fundus image?

A
  • High refractive error
  • Uncorrected Astig
  • Media opacity
25
Q

How to resolve media opacity?

A
  • tilt ophthalmoscope to view around opacities

- dilate

26
Q

How to resolve insufficient FOV (ophthalm)?

A
  • move closer to px
  • hold ophthalmoscope closer to eye
  • semicircle aperture?
27
Q

How to resolve unable to visualise fundus?

A
  • check alignment
  • hold px’s lids
  • dilate
28
Q

How to resolve unable to visualise macula?

A
  • direct px to look to top edge of light

- change aperture/light intensity

29
Q

How to resolve excessive reflections?

A
  • check alignment/tilt ophthalmoscope

- direct px fixation: not straight into light

30
Q

Why would you want to adjust the brightness of your ophthalmoscope?

A

You may want to reduce brightness to:

  • reduce/minimise pupil constriction
  • minimise px pain
31
Q

Benefit of small aperture? (Medium actually because they call our small “micro”)

A

Provides easy view of the fundus through an undilated pupil. start with this aperture

32
Q

Purpose of cobalt blue filter

A

(used in conjunction with fluorescein dye)

- is helpful in detecting corneal abrasions and foreign bodies

33
Q

When performing opthalmoscopy (direct or MIO), where should the examiner be positioned?

A

15 degrees temporal side of patient

i.e. 15 deg temporal to the visual axis of the patient. Patient will be looking straight ahead

34
Q

How can you obtain the largest view using MIO?

A

Compress the eyecup halfway against the patient’s brow

- (this allows the user to view the entire optic disc + many surrounding vessels at one time)

35
Q

To examine the extreme periphery (MIO), instruct the patient to do what?

A
  • look up to examine superior retina
  • look down to examine inferior retina
  • look temporally to examine temporal retina
  • look nasally to examine nasal retina
36
Q

What are the benefits of MIO?

A
  • more peripheral view is possible (in undilated pupils)
  • less dependent on px’s refractive error
  • greater distance b/w px and optom (comfort)
  • uncooperative children
  • fundus screening
  • px intolerant of bright BIO illumination
  • monocular examiner unable to appreciate advantages of BIO
37
Q

What is considered the technique of choice for looking at fundus? Why?

A

BIO - b/c it allows depth perception (3d images)

38
Q

What is a normal cup disc ratio (C/D)?

A

0.30 or 0.35 (0.35)

39
Q

What is a normal Artery to Vein ratio (diameter) (A/V)?

A

2:3

40
Q

What colour is the normal fundus/posterior pole? What may be visible?

A
  • red/yellow (pinkish tinge)
  • temporal half may appear paler
  • cupping may appear whitish
  • lamina cribroa may be visible
41
Q

What rule does the normal fundus follow?

A 
ISNT rule I>S>N>T (in terms of size of neuroretinal rim)
I = inferior region/border
S = superior
N = nasal
T = temporal
42
Q

What is the normal fundus elevation?

A

flat with slight central cupping (cup less than 0.5 of vertical diameter)

43
Q

What is the normal fundus border?

A

distinct, possibly with surrounding pigment or pale crescent

44
Q

What do veins look like compared to arteries in fundus examination?

A

veins are darker shade of red compared to arteries

45
Q

What is AV nicking (arteriovenous nicking)?

A

Is the phenomenon where, on examination of the eye, a small artery (arteriole) is seen crossing a small vein (venule), which results in the compression of the vein with bulging on either side of the crossing.

– this is most commonly seen in eye disease caused by high blood pressure (hypertensive retinopathy)

46
Q

What are the arteriovenous crossings like in a normal fundus?

A
  • no compression at all
  • no deviation
  • no banking
47
Q

Is spontaneous venous pulsation seen in fundus? Where?

A

spontaneous venous pulsation is commonly seen (up to 80%) as you exit the optic nerve head

48
Q

What pattern does the normal Retinal Nerve Fibre Layer (RNFL) follow?

A

Bright, Dark, Bright

49
Q

What does the normal macula look like in fundus exam?

A

macula apears darker than surrounding retina

OD1 Semester 2 - Integrated Ophthalmic Sciences and Preclinical Optometry (49 decks)

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