examining the fundus Flashcards
what is ophthalmoscopy?
examining the eye: looking at the external eye , the optic media ( middle of eye )and the fundus ( back of eye )
what is fundoscopy ?
examining the fundus
what do we use ophthalmoscopy to detect ?
- 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
what are the types of ophthalmoscopy ?
- direct ophthalmoscopy
- panoptic
- indirect ophthalmoscopy which is divided into
. slit lamp with condensing lens
. head-mounted
what is direct ophthalmoscopy ?
- 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
what does the term direct mean in direct ophthalmoscopy ?
- term direct refers to the fact that when we doing direct ophthalmoscopy we are viewing the eye and the fundus directly
what are some characteristics of direct ophthalmoscopy ?
- 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
explain the various structures of a direct ophthalmoscope ?
. there’s a system of lenses ( for focusing ) and different illumination
. we can adjust the lenses to get a clear view
what type of lenses do we use for direct ophthalmoscopy to view fundus ?
- to view the fundus we need to use lenses that correct for refractive error ( yours and the patient’s ) and viewing distance
what is the function of power wheel in a direct ophthalmoscope ?
- 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
when are auxilliary lenses used in a direct ophthalmoscope ?
- we use them we making really big changes in lens power
- not used very often
what is the function of the focusing dial at the top of direct ophthalmoscope ?
- we use this to change auxilliary lenses
not used very often
what is the function of filters in direct ophthalmoscope ?
help enhance or improve our view of certain structures and features
function of focusing lenses in direct ophthalmoscope ?
what is usually used to focus an ophthalmoscope
how to add patient’s and clinician’s refractive error when using a direct ophthalmoscope ?
- emmetropic examiner and emmetropic px
. fundus in focus with 0D - -5.00Dexaminer/emmetropic px
. fundus focus with -5.00D - -5.00D examiner / -3.00 D Px
. fundus focus with -8.00D
- emmetropic examiner /-4.00 px wearing contact lenses
. fundus focus with 0D
as px is wearing contact lenses
explain direct ophthalmoscopy routine ?
. 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
what is ideal working distance when using a direct ophthalmoscope ?
2 cm
what do you see with an ophthalmoscope ?
- 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 )
how to view the external eye with an ophthalmoscope ?
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
what do to do after examining external eye using an ophthalmoscope
- 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
what to do after checking the four corners of eye ?
- 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 - continue to reduce power of the focusing lens to focus on the vitreous - allow to see floaters of the eye
- continue reducing lens power until fundus is in focus
. 2cm from cornea
what is first thing you want to look for when examining the fundus ?
. 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
how to locate the fovea ?
- 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
what is function of macula ? and where is it located
- responsible for central most detailed vision
- the macular region lies about 15 deg temporal to the optic disc and is long the visual axis
