ffERG -VEP disparity or dissociation has different factors , mainly central vs peripheral pathology and Inner layers vs outer layer pathology , both flash VEP and ffERG for me are indicators only not denominators
Matt is right about of course it is a primary retinal pathology no doubt but I saw many cases of VKH with optic nerve pathology and few of them presented primarily with optic neuritis - papilledema and got diagnosed through investigations
Original Message:
Sent: 4/18/2026 10:27:00 PM
From: Alfredo Sadun
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Hi Matt,
This is news to me! IpRGCs or melanopsin RGCs, project primarily to the pretectum, to three nuclei of the hypothalamus, to the superior colliculus and even to some layers of the LGN. But, to my knowledge, they do not bypass the brain stem to project directly to the visual cortex.
Alfredo
Original Message:
Sent: 4/18/2026 9:05:00 PM
From: Matthew Kay
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
The ipRGCs Likely project to the visual cortex directly and might still respond to a flash VEP in the setting of an extinguished ERG. However, this case still almost certainly represents a primary retinal process Given the extinguished e r g.
Original Message:
Sent: 4/18/2026 12:30:00 PM
From: Sherif Ahmed Kamel Abdelbar
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Yes could be in ffERG , called functional disparity or dissociation
Original Message:
Sent: 4/18/2026 12:05:00 PM
From: Andrew Carey
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Is a visual electrical potential test valid in the setting of a non-detectable full-field ERG? How will the signal get from the photoreceptors to the optic nerve if the photoreceptors aren't functioning?
Original Message:
Sent: 4/18/2026 11:34:00 AM
From: Floyd Warren
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Unfortunately, with HM. Vision, can probably only get av flash VEP
Original Message:
Sent: 4/18/2026 10:48:00 AM
From: Sherif Ahmed Kamel Abdelbar
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Yes for sure I agree but what I wanted to say is to add VEP and pattern ERG so it may add some data
Original Message:
Sent: 4/17/2026 8:01:00 PM
From: Matthew Kay
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
An extinguished Fulfield e r g Implies widespread photoreceptor damage as opposed to a multifocal e r g for focal macular processes while optic neuritis would demonstrate optic nerve enhancement and papilledema would be readily visible on fundus exam. They could certainly have combined retinal and optic nerve pathology, But the retinal pathology must be diffuse given the ERG and could certainly account for hand motions vision.
Matt
Original Message:
Sent: 4/17/2026 3:35:00 PM
From: Sherif Ahmed Kamel Abdelbar
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Yes for sure but focal retinal pathology hardly cause HM vision so I was thinking about double pathology , either contiguous optic neuritis with uveitis or papilledema
Sherif
Original Message:
Sent: 4/17/2026 3:29:00 PM
From: Matthew Kay
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
As the erg is extinguished, this is primarily retinal not the nerve.
Matt
Original Message:
Sent: 4/17/2026 7:34:00 AM
From: Sherif Ahmed Kamel Abdelbar
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Definitely this looks like optic nerve affection rather that retinal , if we have VEP can add some information , except there is more massive subretinal fluid , I would go first for pulse steroids first before deciding with the immunologist and Uveitis specialist what sort of maintenance therapy would be suitable
One second thing is that it is not uncommon to have elevated ICP resembling IIH in those cases , are there any doubts about that , is there any suspicion of papilledema
Original Message:
Sent: 4/16/2026 11:45:00 PM
From: Ajay Patil
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Hi Yan,
If happy that the diagnosis is VKH (exam/FFA/ICG all consistent), aggressive acute treatment / induction with IVMP is crucial in limiting retinal damage/avoiding depigmented fundus. Important to also titrate steroids to choroidal thickness and not just resolution of vision/exudative detachments.
VKH is also one of the few uveitic entities that warrants long term immunosuppression at the outset so the sooner something is commenced the better, as will take some time to take effect (eg Aza in a young male).
Good luck!
Ajay Patil
Neuro-ophthalmology & Uveitis
University Hospitals Birmingham, UK
Original Message:
Sent: 4/16/2026 8:38:00 PM
From: Andrew Carey
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Hi Yan,
If there is photoreceptor dysfunction (as evidenced by the ERG l) and the retina looks okay, you have to look in the choroid (which provides oxygen / nutrients to photoreceptors) which means ICGA / FFA.
Have to wonder about choroidal ischemia / vasculitis / infection.
Original Message:
Sent: 4/16/2026 8:15:00 PM
From: Yan Yan
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Hi Drew,
Thanks for the opinion. It occurred while maintaining a dose of 50mg of prednisone, without any dose lowering. The fundus examination showed significant improvement, which means the ophthalmic findings clearly indicate a response to steroids. There were multifocal neurosensory retinal detachments and thickened, edematous choroid before using steroids. And now there is only subfoveal fluid, basically normal fundus. The anterior chamber cells have also resolved. She has no history of any ocular surgery or trauma. Currently, there is a symptom-sign dissociation.
Best,
Yan
Original Message:
Sent: 4/16/2026 8:00:00 PM
From: Andrew Carey
Subject: RE: Acute VKH with sudden vision drop to HM and steroids not working
Hi Yin,
What a tough case. This process doesn't make sense. Was the Prednisone dose lowered and then the patient got worse?
If the full field ERG is reliable and there truly is non-detectable waveforms, then there has to be widespread retinal photoreceptor dysfunction which should not occur acutely in the setting of a normal fundus. If the patient is worse on steroids, you need to reevaluate the diagnostic process. I would repeat the fluorescein angiogram along with an ICG angiogram and fundus autofluorescence as well as macular OCT.
Getting worse on high dose oral steroids, especially if initially responding would not be consistent with VKH, I would be highly concerned for an infectious process and you may need to do anterior chamber and or vitreous biopsy for viral PCRs and consider lumbar puncture for the same. TB and sympathetic ophthalmia / sarcoid can mimic VKH as well syphllilis and lymphoma, although sympathetic ophthalmia and sarcoid should not worsen on steroids.
Mycophenolate will take 2-4 weeks or more to start working and it does not sound like this patient has weeks to wait. If infection is ruled out, the next steps would be IV steroids and consideration of cyclophosphamide given the rapid decline but it helps if you know what you are treating.
Best of luck to you and your patient,
Drew
Original Message:
Sent: 4/16/2026 7:43:00 PM
From: Yan Yan
Subject: Acute VKH with sudden vision drop to HM and steroids not working
Hi Dear All,
I have a patient for whom I would appreciate your opinions.
A previously healthy 32-year-old female with acute VKH is on oral prednisone 50 mg daily for two weeks. FFA and OCT findings are typical for VKH, with a few cells in the anterior chamber. Repeat OCT shows significant improvement, with only subfoveal fluid. However, the patient reports worsening vision, and progress within a few days, her visual acuity drops from 20/50 to HM in both eyes, without having received any other immunosuppressive agents. Orbital and brain MRI w/o contrast are unremarkable. CBC and basic metabolic panel show no abnormalities. Serum AQP4 and MOG antibodies are negative. Syphilis, HIV, ACE, and ANA are also negative. Chest x-ray is normal. The uveitis specialist added mycophenolate later.
When I saw the patient, visual acuity was HM in both eyes, both pupils were 4 mm with no reaction to light, the anterior chamber was quiet, and the fundus appeared normal. A full-field ERG showed nearly undetectable waveforms. I ordered anti-retinal antibodies but the results are still pending. I am considering IVMP 1 g, but I'm not sure whether steroid pulse therapy will be effective in her case. Should PLEX or IVIG be prioritized instead? Is a PET-CT also indicated?
Any input is welcome.
Thanks!
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Yan
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