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examining the fundus Flashcards

1
Q

what is ophthalmoscopy?

A

examining the eye: looking at the external eye , the optic media ( middle of eye )and the fundus ( back of eye )

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2
Q

what is fundoscopy ?

A

examining the fundus

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3
Q

what do we use ophthalmoscopy to detect ?

A
  • used to detect signs of cataract which affects the crystalline lens of the eye
  • retinoblastoma - condition that affects children
  • hypertension - high blood pressure
  • diabetes
  • macular disease
  • optic nerve inflammation
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4
Q

what are the types of ophthalmoscopy ?

A
  • direct ophthalmoscopy
  • panoptic
  • indirect ophthalmoscopy which is divided into
    . slit lamp with condensing lens
    . head-mounted
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5
Q

what is direct ophthalmoscopy ?

A
  • px must be in a dark and grey
  • clinician shines a beam of light through the pupil using an instrument called ophthalmoscope and looks through the eye piece
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6
Q

what does the term direct mean in direct ophthalmoscopy ?

A
  • term direct refers to the fact that when we doing direct ophthalmoscopy we are viewing the eye and the fundus directly
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7
Q

what are some characteristics of direct ophthalmoscopy ?

A
  • monocular image - we look through one eye as the examiner when look at the patient
  • real ( direct ) image
  • small field of view - not able to see everything in one go - we must be able to move ophthalmoscope around to be able to view all the features
  • high magnification - 15 x
  • portable
  • no other equipment needed
  • no pupil dilation needed
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8
Q

explain the various structures of a direct ophthalmoscope ?

A

. there’s a system of lenses ( for focusing ) and different illumination
. we can adjust the lenses to get a clear view

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9
Q

what type of lenses do we use for direct ophthalmoscopy to view fundus ?

A
  • to view the fundus we need to use lenses that correct for refractive error ( yours and the patient’s ) and viewing distance
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10
Q

what is the function of power wheel in a direct ophthalmoscope ?

A
  • to take into account for the distance we are viewing at and to do this we use the power wheel
  • it’s the big wheel on the back of the ophthalmoscope
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11
Q

when are auxilliary lenses used in a direct ophthalmoscope ?

A
  • we use them we making really big changes in lens power

- not used very often

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12
Q

what is the function of the focusing dial at the top of direct ophthalmoscope ?

A
  • we use this to change auxilliary lenses

not used very often

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13
Q

what is the function of filters in direct ophthalmoscope ?

A

help enhance or improve our view of certain structures and features

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14
Q

function of focusing lenses in direct ophthalmoscope ?

A

what is usually used to focus an ophthalmoscope

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15
Q

how to add patient’s and clinician’s refractive error when using a direct ophthalmoscope ?

A
  1. emmetropic examiner and emmetropic px
    . fundus in focus with 0D
  2. -5.00Dexaminer/emmetropic px
    . fundus focus with -5.00D
  3. -5.00D examiner / -3.00 D Px

. fundus focus with -8.00D

  1. emmetropic examiner /-4.00 px wearing contact lenses

. fundus focus with 0D
as px is wearing contact lenses

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16
Q

explain direct ophthalmoscopy routine ?

A

. explain to px what you are going to do (going to use this to look at the health of your eyes)
. tell px what to look at i.e. fixation target ( distant target straight ahead )
. px sits at similar or lower level
. no spectacles ( unless px is very high myope )
. turn off room illumination
. observer stands on side of examined eye
e.g. if examining px right eye use your right eye and if you are examining patient’s left eye you use your left eye
. RE for RE and LE for LE

. not suitable for amblyopic clinician

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17
Q

what is ideal working distance when using a direct ophthalmoscope ?

A

2 cm

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18
Q

what do you see with an ophthalmoscope ?

A
  • the pupil - as you get closer to pupil you will have a higher field of view
    will see a red reflex = reflection from retina (posterior surface )
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19
Q

how to view the external eye with an ophthalmoscope ?

A

1.start by viewing external eye
2. px eye closed
. viewing distance 10cm
. using a high power lens ( +10 if both you and px are emmetropic ) + ( in addition to your refractive error - not patients r.e )
e.g. if you’re refractive error is -2 you want use +8 lens

20
Q

what do to do after examining external eye using an ophthalmoscope

A
  1. reduce power slightly to view the iris and the lens
    . ask px to look up , down , left and right in order to get a good view of all corners of eye (4 position gaze)
    . at this point you are able to observe red reflex
    . reflected light from the choroid or retina
    . opacities appear dark against this light ( cataract )
    . adjust brightness ( use aperture size )
    large aperture = external eye
    medium aperture= fundus
    small aperture = view macula
    . place your free hand on headrest behind px or on px shoulder or forehead- to stabilise yourself- not shaking
21
Q

what to do after checking the four corners of eye ?

A
  1. start to reduce power of focusing lens ( rotate power wheel ) and check clarity of media
    . ask px to look up , down , right , left
    . swing 30 deg up , down , right , left
  2. continue to reduce power of the focusing lens to focus on the vitreous - allow to see floaters of the eye
  3. continue reducing lens power until fundus is in focus
    . 2cm from cornea
22
Q

what is first thing you want to look for when examining the fundus ?

A

. optic disk is ALWAYS located around 15 deg nasally to the fovea
. fovea is located on visual axis completely centrally
. to view optic disk we would look along an axis about 15deg from the visual axis on the patient’s temporal side illuminating a nasal location on the fundus
. in RE to move light to right we move ourself to the left
. in LE the optic disk is going to be situated nasally , we will want to move our light to the left of visual axis

23
Q

how to locate the fovea ?

A
  • it’s central part of the macula
  • located 15 deg temporal to optic disk on visual axis
  • to view fovea we would look straight into the eye , along the visual axis
  • you can swing into the patient’s visual axis or ask the patient to look straight into your light
  • reduce illumination and aperture size- can help control the reflections swell
24
Q

what is function of macula ? and where is it located

A
  • responsible for central most detailed vision

- the macular region lies about 15 deg temporal to the optic disc and is long the visual axis

25
Q

what are general features to look for at the macula ?

A
  • the main feature of the normal fovea is there is nothing to see
  • no blood vessels.relatively dark
  • blood vessels ( and ganglion cell axons ) arc around this region but don’t extend into the macula
  • possibly a pin-prick of light at the central fovea- but only in younger eyes
26
Q

how to examine fundus periphery ?

A

. keep working distance ( 2cm )
. patient looks up/down/left/right
. 8 directions of gaze
e.g.
up , up into the right , straight over to the right , down into right , straight down, down to the left , straight over to the left and up and left
. you adjust your viewing angle too
. examine the retinal background and the blood vessel “ tree “

27
Q

why do you crouch down to get a good view of the patient’s superior retina ?

A
  • when patient looks up . view of superior fundus
  • when you move down you’re able to tilt your light up more and then you’re able to view even further into the superior periphery
28
Q

what are some tips for direct ophthalmoscopy ?

A
  1. use your hand to judge distance from the patient’s eye
    external = 10 cm viewing distance
    fundus = 2cm
  2. use small aperture for small pupils
  3. keep your index finger on the power wheel for easy focusing
  4. when needed , gently hold lids with your thumb
    - for inferior fundus viewing
    - to minimise blinks in photophobic patients
  5. have your other eye open or close
29
Q

what is panoptic direct ophthalmoscope ?

A
  • image produced by panoptic is an indirect image
  • monocular - can be used with either eye - good for amblyopic practitioners due to greater working distance
  • easy for small un dilated pupils
  • enables a 25deg field of view vs the standard 5deg field of view with standard direct ophthalmoscope
  • increases magnification by 26% over a standard ophthalmoscope
  • greater working distance than direct ophthalmoscope - it can be used for amblyopic practitioners
30
Q

what are the advantages and of direct ophthalmoscope ?

A
  • evaluation of posterior eye ‘un dilated’
  • portable
  • minimal patient cooperation needed
  • image right way up ( erect )
  • med-high magnification of fundus ( 15x )
  • easy to master and perform
  • patient comfort
31
Q

what are the disadvantages of direct ophthalmoscope ?

A
  • limited field of view
    ( approximately 5 deg )
  • no depth perception
  • refractive error can distort view
  • cloudy media/media opacities can reduce view
  • short working distance ( 2cm )
32
Q

How is the eye viewed in direct opthalmopscopy ?

A

actual fundus features are viewed directly in their real locations
-direct image f

33
Q

How is the eye viewed in indirect ophthalmoscopy ?

A
  • indirect image- formed between the lens we are using to view image and our eye- get an aerial image.
  • Fundus features are inverted horizontally and vertically and (laterally reversed) - which means the image we are seeing are back to front and upside down
34
Q

What is the 1st method of the binocular indirect ophthalmoscopy?

A

Using a Slit lamp with a condensing lens

35
Q

What do we see with a slit lamp with a condensing lens ?

A
  • Have an additional lens that a practitioner holds in own hand infront of the patients eye.
  • Binocular image is formed- asses the depth of the features viewing
  • Image is back to front
  • image inverted and reversed (upside down)
  • Large field of view
  • use a Condensing (e.g. Volk) lens of varying powers , +66D, +78D, +90D (
  • The stronger the power of the condensing lens, the closer it must be held to the eye
  • Pupil dilation may be needed to obtain a good view
36
Q

What can you see from looking through the slit lamp with condensing lens?

A

see a slit and able to move the slit around to see the whole fundus

37
Q

What is the advantages of using a SL with a condensing lens ?

A

Independent of patients Rx
• Magnification approx 5x -70X (can really vary mag)- can change the condensing lens we use - as they have different magnifying powers as well as having a magnification setting - good range

38
Q

What is the 2nd method of binocular indirect ophthalmoscopy ?

A

.Head mounted BIO (binocular indirect opthalmoscopy )

39
Q

How is the practioner prepared to do a Head mounted BIO?

A
  • Practioner wears a head set - observation of illumination system is in this.
  • practioner holds condensing lens infront of the eye
  • condensing lens used is different to slit lamp method.
40
Q

What do we see in the indirect ophthalmoscopy methods ?

A

-To view the eye and fundus indirectly (virtual image)

41
Q

What do we see in a Head mounted BIO?

A

Binocular image

  • Back-to-front image which is
  • Inverted
  • Reversed
  • image is formed between the condensing lens and practitioners eye
  • Large field of view
  • Condensing lens +20D - Independent of Rx
  • Magnification ~2x -5X
  • Pupil dilation needed -
42
Q

What is a big advantage of head mounted BIO over SL?

A
  • portable method- take headset wherever
  • doesnt require patient to put head on a chin rest - so helpful with patients with mobility problems or more difficulty sitting on a SL - useful
43
Q

Where is the Head mounted BIO commonly used?

A

paediatric clinics - less daunting for children

44
Q

What are some limitations of direct and indirect opthalmocopy ?

A
  • Ophthalmoscopy view can be limited by small pupils
  • Restricted fundus view
  • May be necessary to dilate pupil
45
Q

How is the pupil dilated for a better view?

A

-A large dilated pupil is obtained with the use of eye drops

46
Q

what is pupil dilation known as ?

A

Pupil dilation is known as ‘mydriasis’

-The relevant drops are ‘mydriatic’ or ‘cycloplegic’

47
Q

What causes a small pupil ?

A
  • Age (older patients)
  • Side effect of some drug use-
  • Bright light

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