RAPD or Marcus Gunn Pupil
Alternatively shine a light back and forth on each pupil and observe.
1 second interval in a diy lit room. Ask pt to fixate on a distant object
Avoid spillover of light (as seen here)
Look carefully, zoom in to each!
Different ?
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Alternatively shine a light back and forth on each pupil and observe.
1 second interval in a diy lit room. Ask pt to fixate on a distant object
Avoid spillover of light (as seen here)
Look carefully, zoom in to each!
Different ?
#MedTwitter #MedEd
Simplified.
Normally when light is shined in the Left eye (afferent)β retina β Left Optic Nerve β Pretectal Nucleus β Edinger Westphal Nuc of BOTH SIDES β efferent Oculomotor Nerve β CONSTRICTION OF LEFT pupil (direct) and RIGHT (Consensual)
Normally when light is shined in the Left eye (afferent)β retina β Left Optic Nerve β Pretectal Nucleus β Edinger Westphal Nuc of BOTH SIDES β efferent Oculomotor Nerve β CONSTRICTION OF LEFT pupil (direct) and RIGHT (Consensual)
In our little friend, Right Optic Nerve is damaged
Light in Left- Normal constriction in both eyes
Light is shined in right, since the βAFFERENTβ Optic nerve is damaged, there is no pupillary response
Light in Left- Normal constriction in both eyes
Light is shined in right, since the βAFFERENTβ Optic nerve is damaged, there is no pupillary response
Hence after shining the light in the left, when we go to the right, the right pupil which is constricted (consensually) , lacks the ability to constrict to direct light, hence appears to dilate (βRelativeβ)
See the video again, initially left pupil constricts. When I move the light to the right, carefully look for the initial dilation. Zooming in may help
This needs to be differentiated from Hippus that is a rapid fluctuating pupil size. Usually a normal phenomenon. Watch the initial movement closely, it will dilate or constrict (50-50) but RAPD has initial dilation
If there is bilateral vision loss, obviously, an RAPD will not be elicited
Causes of RAPD
-Optic Neuritis (because of MS NMO Idiopathic)
-Optic Nerve Damage (Trauma Radiation Tumour)
-severe Glaucoma
-retinal detachment, infections (CMV)
- ischaemic optic neuropathy
Causes of RAPD
-Optic Neuritis (because of MS NMO Idiopathic)
-Optic Nerve Damage (Trauma Radiation Tumour)
-severe Glaucoma
-retinal detachment, infections (CMV)
- ischaemic optic neuropathy
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