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Neuro-Ophthalmological Findings in Patients with Posterior Circulation Stroke
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
The most common visual field defect when one hemisphere is infarcted is a hemianopia. Patients usually report inability to see to the hemianopic side, or a void, or grayness to that side. The hemianopia is most often homonymous and congruent. The responsible lesion is usually an occipital lobe infarct (Figure 23.1). When the hemianopia is complete and splits the macula, the lesion usually involves the optic radiations subcortically or includes the calcarine cortex from the occipital pole to the anterior occipital region. In some patients, the macular, central, region of the hemianopic field adjacent to the vertical meridian is relatively spared. This central portion of the visual field is represented in the posterior portion of the striate cortex (VI) near the occipital pole. Macular sparing usually means that the occipital pole is preserved and that the lesion likely involves striate cortex rather than optic radiations. If there is macular sparing, the occipital poles are likely supplied, in addition to the PCAs, by collaterals from the middle cerebral arteries (MCAs).
Visual cortex
Published in Fiona Rowe, Visual Fields via the Visual Pathway, 2016
Occlusion of the posterior cerebral artery can produce a macular sparing congruous homonymous hemianopia (Leff 2004). If macular sparing occurs, it is diagnostic of an occipital lobe lesion since it is rarely encountered with lesions outside the visual cortex and is therefore of localising value. Macular sparing occurs due to the separate blood supply of the posterior cerebral artery and middle cerebral artery to the visual cortex (Ehlers 1975; Smith and Richardson 1966). The macular fibres typically receive vascular supply at the occipital cortex from the middle cerebral artery.
Proceedings of the 43nd Annual Upper Midwest Neuro-Ophthalmology Group Meeting, July 23, 2021 and Second Virtual Upper Midwest Neuro-Ophthalmology Group Meeting
Published in Neuro-Ophthalmology, 2021
Deena Tajfirouz, Casey Judge, John J. Chen, Collin McClelland
Jonathan Trobe MD, University of Michigan, presented a retrospective investigation showing the correlation of macular sparing and homonymous paracentral scotomas with lesion location in posterior cerebral artery (PCA) ischaemic strokes. A cohort of 94 patients whose magnetic resonance imaging (MRI) showed exclusive PCA territory infarcts were studied. The study found that lesions sparing the posterior 50% of the visual cortex often produced macular sparing of the central 15 degrees of the visual field with no significant difference in the visual field spared when comparing pathology sparing 25% versus 50% of the posterior visual cortex. Homonymous paracentral scotomas confined to the central 15 degrees of the visual field were associated with lesions isolated to the posterior 50% (or less) of the visual cortex. This study supports that the central 15 degrees of the visual field is mapped onto at least 50% of posterior visual cortex.
Clinical and Imaging Findings One Year Following Traumatic Chiasm Transection
Published in Neuro-Ophthalmology, 2019
Ayman G. Elnahry, Gehad A. Elnahry
Traumatic chiasm transection (TCT) is a rare condition characterized by bitemporal hemianopsia following head trauma. In a study of visual complications following head trauma, only 4.4% of patients suffered from chiasmal injuries.1 Injury to the chiasm can range from small tears to complete transection of the chiasm which is even more rare.2 Most injuries occur following frontal head trauma and are often associated with skull fractures.2,3 Injuries to the chiasm following head trauma can result from the mechanical stretch, compression by a hematoma or cerebral oedema, and by contusion necrosis.2 MRI is the best imaging modality to diagnose TCT and can reveal complete transection.2,4 Reported visual acuity following TCT is variable and can be different between both eyes.2 Macular splitting is a condition which occurs in hemianopic patients in which the scotoma reaches the fixation point leading to eccentric or unstable fixation. It is commonly reported with chiasmal injury.5 Macular sparing denotes sparing of the vision in the central area of the visual field and can be missed with standard automated perimetry using the 30–2 pattern.5,6 Hemifield slide phenomenon is a condition in which there is vertical or horizontal displacement of the visual fields in the absence of muscle paresis in patients with heteronymous hemianopsia.7,8 This occurs due to loss of binocularity in these patients with loss of the ability to fuse the visual fields of both eyes. This may lead to instability of ocular alignment and ocular deviations as in the presented case.7,8
Pigmentary retinopathy with perivascular sparing in a SOFT syndrome patient with a novel homozygous splicing variant in POC1A gene
Published in Ophthalmic Genetics, 2023
Bilge Batu Oto, Deniz Ağırbaşlı, Oğuzhan Kılıçarslan, Gökhan Celik, Aysel Kalayci Yigin, Mehmet Seven, Hüseyin Yetik
In ophthalmic external examination, hypertelorism was observed, and interpupillary distance was measured as 51 mm. Visual acuity could not be evaluated properly with Snellen or Lea charts since the patient had limited contact with anyone outside the family but maintained a central and steady object tracking. Patient had orthophoric gaze in Cover-test, and glob movements were bilaterally normal. Anterior segment was evaluated normal in slit-lamp biomicroscopy. Fundus examination revealed bilateral yellow-white punctate retinal pigment epithelium lesions which were located in the perivascular areas in the midperipheral retina. Macular sparing of lesions was observed (Figure 3a). These pigmentary changes followed major vascular arcades but had a narrow clear zone around macrovessels. Increased venous tortuosity was prominent especially in the peripapillary area, but macular reflex was normal bilaterally. Macular anatomy was normal bilaterally in spectralis optical coherence tomography (Figure 3b). In fundus autofluorescence, the lesions appeared hyperautofluorescent (Figure 3c). Full-field ERG was performed via gold foils according to ISCEV standarts. In dark adapted 0.01 full-field flash ERG, a wave amplitude (38 µV) was slightly low and a wave implicit time (27 ms) was slightly delayed. Amplitude of b wave was 115 µV and b wave implicit time was 112 ms (both of them in lower limits by age) in this response. Photopic 3.0 30 Hz flicker response was in normal borders. Amplitude of a wave was 30 µV and b wave was 102 µV, implicit time of a wave was 16 ms and b wave was 28.8 ms in photopic 3.0 bright flash full-field ERG (were all in normal borders by age).