I am certain that the group is familiar with this study by Seymour Hershenfeld and Jim Sharpe regarding monocular temporal hemianopsia that showed a surprising number of lesions in the region of the chiasm.
Monocular temporal hemianopia
Seymour A Hershenfeld, James A Sharpe
British Journal of Ophthalmology 1993; 77:424-427
Abstract
Monocular temporal hemianopia was identified in 24 patients. The field of the fellow eye was normal. Computed tomography or magnetic resonance imaging showed juxtasellar lesions in 19 patients. Fifteen had pituitary adenomas, two had tuberculum sella meningiomas, one a craniopharyngioma, and one an astrocytoma. One patient had optic neuritis. A relative afferent pupillary defect (RAPD) was detected in most patients. Field loss was functional in two. Two had congenital optic disc dysversion with hemianopia which did not respect the vertical meridian. Monocular temporal hemianopia is attributed to involvement of the ipsilateral optic nerve close enough to the chiasm to selectively impair conduction in
crossing nasal retinal fibres from the ipsilateral eye, but too anterior to affect crossing nasal retinal fibres from the contralateral eye. The combination of an RAPD, with or without optic disc pallor, on the side of monocular temporal field loss implicates compression of the optic nerve at its junction with the chiasm.
Janine
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Janine L. Johnston BScPharm., MD FRCPC FAAN
Neuro-ophthalmology and Neuro-otology
Thomson House Medical Consultants
Professor
Section of Neurology
Departments of Medicine and Ophthalmology
University of Manitoba
Original Message:
Sent: 1/29/2026 8:13:00 AM
From: Michel Van Lint
Subject: RE: temporal vision loss
I have around 10 patients with unexplained monocular temporal hemianopia. A few years ago, I presented this at a local meeting, but I was met with skepticism. One of the attendees did not believe me and became rather annoyed. In two patients I believe there was a possible explanation: a prechiasmal meningioma in one, and an optic neuritis in the other. The weird thing is, most patients are willing to do all sorts of tests, but then never return after saying we don't understand. Actually, there was a third patient where we found a cause: instead of the right eye the monocular loss was suddenly in the left eye after some delayed follow-up :)
Edit to add: Some of the patients I asked to look nasally with the affected eye and when I presented a small light at the slitlamp at the nasal retina, they would not always be able to see the light
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Original Message:
Sent: 01-28-2026 12:15
From: Bradley Katz
Subject: temporal vision loss
In the last 3 months I have seen 3 men, ages 49-67 reporting temporal vision loss in one eye. In all 3 cases, extensive neuro and retina evaluations have been unrevealing. The symptoms seem to wax and wane. There are no positive phenomena like you'd expect with an inflammatory retinopathy. The symptoms do not occur in "spells" like you'd expect if was vascular.
I'm not overly worried that any of them have some sinister illness, but also at a loss for an explanation. Has anyone else seen anything similar or is this epidemic isolated to Utah?
Bradley J Katz, MD, PhD
Professor of Ophthalmology and Visual Sciences
John A Moran Eye Center
he/him/his
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