Chorioretinopathy presenting as bitemporal hemianopia.

INTRODUCTION: Bitemporal hemianopia is usually caused by chiasmal pathology. Rarely, chorioretinal lesions may develop symmetrically in both eyes and mimic chiasmopathy. METHODS: This case series included three patients who presented to a tertiary neuro-ophthalmology centre with bitemporal hemianopic defects between 2021 and 2023 and were subsequently diagnosed with bilateral chorioretinopathy. All patients received comprehensive examinations from a fellowship-trained neuro-ophthalmologist and uveitis specialist to rule out other causes of visual dysfunction. RESULTS: Three males aged 64, 62, and 72 years were included. All patients showed bitemporal hemianopic defects crossing the vertical midline on automated perimetry and binasal thinning of the macular ganglion cell complex on spectral-domain optical coherence tomography (OCT). Fundus autofluorescence (FAF) showed classical features of acute zonal occult outer retinopathy (AZOOR) in two patients and central serous chorioretinopathy (CSCR) in another. AZOOR diagnosis was preceded by neuroimaging in both cases, whereas the patient with CSCR had longstanding, electroretinography-confirmed lesions and did not require neuroimaging. Fundus appearance and visual field defects remained stable in all patients across 3-6 months of follow-up. CONCLUSIONS: Bilateral chorioretinopathy should be considered in the differential diagnosis of bitemporal hemianopia in specific cases, including when visual field defects cross the vertical midline and when neuroimaging fails to reveal chiasmal pathology. FAF and macular OCT have high diagnostic yield as initial investigations.

Risk of pedestrian collision for persons with peripheral field loss: A computational analysis.

SIGNIFICANCE: People with peripheral field loss report colliding with other pedestrians on their blind side(s). We show that, in dyadic collision scenarios between persons, one with field loss, such as homonymous hemianopia, and the other normally sighted pedestrian, collisions occur only if the persons with homonymous hemianopia are overtaking the pedestrians, and the collision risk is concentrated at farther bearing angles than previously suggested. PURPOSE: Prior work computed the risk of collision while simulating both pedestrians as points and did not consider the ability of the other pedestrian's normal vision to avoid the collision. We extended the model to better characterize the open space collision risk posed for persons with homonymous hemianopia by normally sighted pedestrians where both have volume. METHODS: We computed the risk of collision with approaching pedestrians using a model that simulates approaching pedestrians as volumetric entities without vision, volumetric entities with vision, and as points for comparison with the prior work. Collision risk of approaching pedestrians is characterized for all three conditions through spatial collision risk maps and collision risk densities as a function of bearing and radial distances. RESULTS: The collision risk for volumetric pedestrians is slightly different from that of point pedestrians. For volumetric pedestrians simulated with normal vision, the risk of collision was reduced substantially, as the other pedestrians could detect and avoid most impending collisions. The remaining collision risk is from pedestrians approaching at higher bearing angles (>50°) and from shorter radial distances (<2 m). Thus, collisions occurred when the pedestrians started in front of the person with homonymous hemianopia that was overtaking the pedestrian. CONCLUSIONS: The probability of collisions between pedestrians and the person with peripheral field loss is low and occurs only when the person with peripheral field loss is walking from behind the pedestrian at faster speed, thereby overtaking them. Such collisions occur with pedestrians at higher bearing angles, which should be monitored by assistive aids to avoid collisions. The same collision risk applies not only in homonymous hemianopia but also in other peripheral field loss such as monocular vision loss or concentric field loss, as common in retinitis pigmentosa and glaucoma.

The Challenge of Strabismus Surgery for Patients with Hemianopic Visual Field Defects Associated with Ocular Deviations.

Homonymous and heteronymous hemianopias associated with strabismus are a therapeutic challenge because surgery may result in diplopia, decrease the visual field (VF), and/or lead to recurrence of the deviation. We present four cases: two homonymous hemianopias and two heteronymous hemianopias. Of the four patients, three had exotropia and one had esotropia. The origin of hemianopias was neoplastic in two cases and traumatic in two cases. Strabismus surgery was performed in three cases, but only one case had a good result; recurrence of the deviation and diplopia occurred in the other two cases. In conclusion, exotropia may develop as a compensatory mechanism in a patient with congenital or early-onset homonymous hemianopia and realigning the eyes could reduce the binocular VF and cause diplopia. In heteronymous hemianopias, there is little risk of the surgery causing diplopia, but the strabismus is unstable because of the absence of binocular vision and vergence reflexes if VF loss includes the macula. Further, strabismus, in association with hemianopia, may be caused by coexistent cranial nerve and/or gaze palsy. The prognosis, objective, and results of the strabismus operation should be clearly discussed with the patients or their guardians before it is performed if hemianopias are present.

Pilot study of a pedestrian collision detection test for a multisite trial of field expansion devices for hemianopia.

SIGNIFICANCE: Performance-based outcome measures are crucial for clinical trials of field expansion devices. We implemented a test simulating a real-world mobility situation, focusing on detection of a colliding pedestrian among multiple noncolliding pedestrians, suitable for measuring the effects of homonymous hemianopia and assistive devices in clinical trials. PURPOSE: In preparation for deploying the test in a multisite clinical trial, we conducted a pilot study to gather preliminary data on blind-side collision detection performance with multiperiscopic peripheral prisms compared with Fresnel peripheral prisms. We tested the hypothesis that detection rates for colliding pedestrians approaching on a 40° bearing angle (close to the highest collision risk when walking) would be higher with 100Δ oblique multiperiscopic (≈42° expansion) than 65Δ oblique Fresnel peripheral prisms (≈32° expansion). METHODS: Six participants with homonymous hemianopia completed the test with and without each type of prism glasses, after using them in daily mobility for a minimum of 4 weeks. The test, presented as a video on a large screen, simulated walking through a busy shopping mall. Colliding pedestrians approached from the left or the right on a bearing angle of 20 or 40°. RESULTS: Overall, blind-side detection was only 23% without prisms but improved to 73% with prisms. For multiperiscopic prisms, blind-side detection was significantly higher with than without prisms at 40° (88 vs. 0%) and 20° (75 vs. 0%). For Fresnel peripheral prisms, blind-side detection rates were not significantly higher with than without prisms at 40° (38 vs. 0%) but were significantly higher with prisms at 20° (94 vs. 56%). At 40°, detection rates were significantly higher with multiperiscopic than Fresnel prisms (88 vs. 38%). CONCLUSIONS: The collision detection test is suitable for evaluating the effects of hemianopia and prism glasses on collision detection, confirming its readiness to serve as the primary outcome measure in the upcoming clinical trial.

Gaze Scanning on Mid-Block Sidewalks by Pedestrians With Homonymous Hemianopia With or Without Spatial Neglect.

Purpose: The purpose of this study was to investigate gaze-scanning by pedestrians with homonymous hemianopia (HH) when walking on mid-block sidewalks. Methods: Pedestrians with right homonymous hemianopia (RHH), and left homonymous hemianopia (LHH) without and with left spatial neglect (LHSN) walked on city streets wearing a gaze-tracking system. Gaze points were obtained by combining head movement and eye-in-head movement. Mixed-effects regression models were used to compare horizontal gaze scan magnitudes and rates between the side of the hemi-field loss (BlindSide) and the seeing side (SeeingSide), among the three subject groups, and between mid-block walking and street crossing segments. Results: A total of 7021 gaze scans were obtained from 341 minutes of mid-block walking videos by 19 participants (6 with LHH, 7 with RHH, and 6 with LHSN). The average gaze magnitude and scanning rate in mid-block segments were significantly higher towards the BlindSide than the SeeingSide in LHH (magnitude larger by 1.9° (degrees), P = 0.006; scan rate higher by 4.2 scans/minute, P < 0.001) and RHH subjects (magnitude larger by 3.3°, P < 0.001; scan rate higher by 3.2 scans/minute, P = 0.002), but they were not significantly different in LHSN subjects. The scanning rate, in terms of scans/minute (mean, 95% confidence interval [CI]) was significantly lower in LHSN subjects (mean = 6.9, 95% CI = 5.6-8.7) than LHH (mean = 10.2, 95% CI = 8.0-13.1; P = 0.03) and RHH (mean = 11.1, 95% CI = 9.0-13.7; P = 0.007) subjects. Compared to street-crossings, the scan rate during the mid-block segments was lower by 3.5 scans/minute (P < 0.001) and the gaze magnitude was smaller by 3.8° (P < 0.001) over the 3 groups. Conclusions: Evidence of compensatory scanning suggests a proactive, top-down mechanism driving gaze in HH. The presence of spatial neglect (SN) appeared to negatively impact the top-down process.

Undoubtedly unaware of homonymous hemianopia: The contribution of overconfidence to anosognosia of hemianopia.

A new functional deficit caused by a stroke can be understood as a situation of uncertainty that has to prompt deficit discovery and subsequent incorporation into an altered self-perception. Anosognosia for visual field deficits is frequent after stroke. For hemiplegia, patients' performance in a riddle test provided evidence that the inability to generate and adjust beliefs in face of uncertainty contributes to anosognosia for hemiplegia. In this prospective study, the same riddles are used in patients with homonymous hemianopia due to a first-ever stroke in the posterior cerebral artery territory and in an age-matched control cohort. The riddles create a situation of uncertainty that is resolved with five successive clues which progressively delimit the target word. After each clue, patients have to guess the target word and rate their confidence in the answer's correctness. Patients were tested once during the hospital stay. According to the Bisiach score for anosognosia, 12 out of 29 patients were unaware of their visual field deficits. All patients with anosognosia for hemianopia had right hemisphere lesions. Patients with and without anosognosia did not differ significantly in global cognitive impairment, mental flexibility or memory function. Importantly, patients with anosognosia showed higher confidence ratings than patients without anosognosia and controls in the first two clues (situations of uncertainty). This was demonstrated by a significant interaction effect in a mixed ANOVA with the factors group (anosognosia, nosognosia, controls) and riddle clues. An exploratory lesion subtraction analysis showed a high proportion of deficit unawareness in patients with lesions in the right fusiform and (para)hippocampal gyri. Our findings suggest that overconfidence in situations of uncertainty might contribute to the appearance of anosognosia for hemianopia. Because this has been demonstrated before in anosognosia for hemiplegia, we suggest that overconfidence is a supra-modal contributor to deficit unawareness.

Vertical infantile nystagmus: Explanation of why the direction of nystagmus is vertical.

This case report presents a rare case of infantile nystagmus syndrome (INS) in which the direction of infantile nystagmus (IN) was vertical. A 66-year-old woman was referred to our department for investigation of abnormal eye movements. She showed a disordered field of view with a homonymous hemianopia in the lower left quadrant and vertical gaze-evoked nystagmus, but there were no other abnormal neurological findings. She did not complain of an oscillopsia. Imaging revealed that the cause of hemianopia was atrophy and low cerebral blood flow in the right occipital lobe. The vertical nystagmus became strong when attempting to fixate to stationary targets. A reversed optokinetic nystagmus response was observed in the vertical optokinetic nystagmus test. From these eye movements, we diagnosed her nystagmus as vertical IN. Patients with INS see everything by saccades. IN consists of the alternate appearance of saccades and preceding slow eye movements. For these eye movements, a wide visual field is necessary. In this case, vertical IN was caused by the wider vertical than horizontal visual field resulting from homonymous hemianopia. Therefore, the direction of IN is horizontal in most patients with INS because their horizontal visual field is the widest field.

Visual hallucinations of autobiographical memories: a single-case study.

Introduction: We report an epileptic patient who experienced hallucinatory visual experiences of autobiographical memories from her past. These visual experiences were confined to the lower left quadrant of her visual field.Methods: We carried out a single-case study that used brain-imaging, EEG and behavioural methods to study this patient.Results: We found that this patient had an incomplete left inferior homonymous quadrantanopia due to a lesion of right occipital cortex, and also that she showed neurological abnormalities in right temporal cortex, a region that is part of the brain's autobiographical-memory circuit.Conclusion: We attribute the occurrence of this patient's autobiographical-memory hallucinations to the combination of degraded visual input to right temporal cortex plus hyperexcitability of that region.

Measurement of Cerebral Glucose Metabolism in the Visual Cortex Predicts the Prognosis of Hemianopia.

BACKGROUND AND OBJECTIVE: Homonymous hemianopia caused by cerebrovascular disease may improve over time. This study investigated whether functional neuroimaging can predict the prognosis of hemianopia due to cerebral infarction. METHODS: We studied 19 patients (10 men and 9 women) with homonymous hemianopia and compared them with 34 healthy subjects (20 men and 14 women). Cerebral glucose metabolism was measured by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET), 1 to 6 months after the onset. Bilateral regions of interest (ROIs) were selected from the posterior and, anterior striate cortices, extrastriate cortex, and thalamus. Furthermore, semi-quantitative data on cerebral glucose metabolism were obtained for ROIs and compared with the data obtained for homologous regions in the contralateral hemisphere by calculating the ipsilateral/contralateral (I/C) ratio. RESULTS: The I/C ratio for the cerebral glucose metabolism in the posterior striate cortex was high (>0.750) in 8 patients, and the central visual field of these patients improved or showed macular sparing. The I/C ratio for cerebral glucose metabolism in the anterior striate cortex was high (>0.830) in 7 patients, and the peripheral visual field of these patients improved. However, no improvement was observed in 9 patients with a low I/C ratio for cerebral glucose metabolism in both the posterior and anterior striate cortices. CONCLUSION: Measurement of cerebral glucose metabolism in the striate cortex is useful for estimating visual field prognosis. Furthermore, FDG-PET is useful in predicting the prognosis of hemianopia.

Discrimination ability of central visual field testing using stimulus size I, II, and III and relationship between VF findings and macular ganglion cell thickness in chiasmal compression.

PURPOSE: To compare the relationship between macular ganglion cell layer (mGCL) thickness and 10-2 visual field (VF) sensitivity using different stimulus sizes in patients with temporal hemianopia from chiasmal compression. METHODS: A cross-sectional study was conducted involving 30 eyes from 25 patients with temporal VF loss on 24-2 SITA standard automated perimetry due to previous chiasmal compression and 30 healthy eyes (23 controls). Optical coherence tomography (OCT) of the macular area and 10-2 VF testing using Goldmann stimulus size I (GI), II (GII), and III (GIII) were performed in the Octopus 900 perimeter. For the sake of analysis, mGCL thickness and VF data were segregated into four quadrants (two temporal and two nasal) and two halves (temporal and nasal) centered on the fovea, in order to evaluate separately both the severely affected nasal hemi-retina corresponding to the temporal VF sectors and the subclinically affected temporal hemi-retina corresponding to the nasal VF sectors. Data from patients and controls were compared using generalized estimated equations. The discrimination ability of GI, GII, and GIII was evaluated, as was the correlation between mGCL and 10-2 VF sensitivity using GI, GII, and GIII. RESULTS: All mGCL parameters in the nasal and temporal halves of the retina were significantly reduced in patients compared to controls. 10-2 VF test sensitivity using GI, GII, and GIII was significantly lower in patients than in controls (p≤0.008) for all parameters, except the three nasal divisions when using GI (p = 0.41, 0.07 and 0.18) Significant correlations were found between temporal VF sectors (all stimulus sizes) and the corresponding nasal mGCL measurements, with similar discrimination ability. Significant correlations were also observed between all three nasal VF divisions and the corresponding temporal mGCL thickness when using stimulus sizes I and II, but not stimulus size III. CONCLUSIONS: On 10-2 VF testing, GII outperformed GI and GIII with regard to discrimination ability and structure-function correlation with mGCL thickness in the subclinically affected nasal part of the VF in patients with chiasmal compression. Our findings suggest that the use of GII can enhance the diagnostic power of 10-2 VF testing in early cases of chiasmal compression, although further studies are necessary to support this conclusion.

Efficacy of Neuro-Optometric visual rehabilitation in Homonymous Hemianopia.

OBJECTIVES: To assess oculomotor dysfunction and the effectiveness of neuro-optometric visual rehabilitation in improving oculomotor parameters in participants with homonymous hemianopia. MATERIALS AND METHODS: Fifty subjects diagnosed with homonymous hemianopia (HH), referred through the neuro-ophthalmology department, were recruited for the study. All the subjects underwent a detailed neuro-optometric evaluation that included testing for sensory, visuo-motor and oculomotor functions. Subjects with homonymous hemianopia were then prescribed with yoked prisms and were randomized to two treatments at one month, namely group 1: yoked prisms (n = 15) and group 2: yoked prisms with in-office visual search training (n = 15). RESULTS: The mean ± SD age of the subjects was 46 ± 12 years. Subjects with HH exhibited a significant delay in the completion time, response and accuracy of tasks on proactive, saccadic and visual search parameters using the SVI compared to age-matched controls (Independent t-test, p < 0.05). A significant improvement in the reading speed and visual search parameters (RM ANOVA, p < 0.001) was seen post neuro-optometric visual rehabilitation with both yoked prisms and SVI. Statistically significant differences were observed in the reaction time of the visual search paradigms between the two rehabilitative modalities yoked (group1), yoked and SVI (group2) (Mann-Whitney U test, p < 0.001), with the group 2 showing better visual search performance outcomes compared to group 1 (yoked). CONCLUSION: Visual search parameters among participants with homonymous hemianopia improved following combined rehabilitation (yoked prisms and visual search trainng).

Vertical and horizontal reading training in patients with hemianopia and its effect on reading eye movements.

Vertical reading training (VRTr) increases reading speed (RS) significantly in patients with hemianopic field defects (HFD). We ask, how eye movements (EM) contribute to this improvement and whether EM-behavior is affected by the side of HFD. Twenty-one patients, randomly assigned to VRTr or horizontal RTr, trained reading single lines from a screen at home, for 4 weeks. In the clinic, we recorded EM while reading short sentences aloud from a screen before training (T1), directly (T2) and 4 weeks afterwards (T3). RS-screen was correlated with RS during reading printed paragraphs (RS-print) to assess the transfer to everyday life. RS-screen and RS-print correlated positively (horizontal: r > 0.8, vertical: r > 0.9) at all times. Vertical RS did not exceed horizontal RS. We found significant negative correlations of EM-variables and RS-print: in right-HFD with the number of forward saccades (T1: r = - 0.79, T2: r = - 0.94), in left-HFD with the steps during return sweeps (T1: r = - 0.83, T2: r = - 0.56). Training effects remained stable at T3. EM-improvement was specific for the RTr and the side of the HFD: in right-HFD fewer forward saccades after VRTr, in left-HFD fewer steps during return sweeps after HRTr. RTr on a screen transfers to reading printed text in real-life situations.Trial registration: The study was retrospectively registered in the German Clinical Trials register: DRKS-ID: DRKS00018843, March 13th, 2020.

Role of corpus callosum in unconscious vision.

The existence of unconscious visually triggered behavior in patients with cortical blindness (e.g., homonymous hemianopia) has been amply demonstrated and the neural bases of this phenomenon have been thoroughly studied. However, a crosstalk between the two hemispheres as a possible mechanism of unconscious or partially conscious vision has not been so far considered. Thus, the aim of this study was to assess the relationship between structural and functional properties of the corpus callosum (CC), as shown by probabilistic tractography (PT), behavioral detection/discrimination performance and level of perceptual awareness in the blind field of patients with hemianopia. Twelve patients were tested in two tasks with black-and-white visual square-wave gratings, one task of movement and the other of orientation. The stimuli were lateralized to one hemifield either intact or blind. A PT analysis was carried out on MRI data to extract fiber properties along the CC (genu, body, and splenium). Compared with a control group of participants without brain damage, patients showed lower FA values in all three CC sections studied. For the intact hemifield we found a significant correlation between PT values and visual detection/discrimination accuracy. For the blind hemifield the level of perceptual awareness correlated with PT values for all three CC sections in the movement task. Importantly, significant differences in all three CC sections were found also between patients with above-vs. chance detection/discrimination performance while differences in the genu were found between patients with and without perceptual awareness. Overall, our study provides evidence that the properties of CC fibers are related to the presence of unconscious stimulus detection/discrimination and to hints of perceptual awareness for stimulus presentation to the blind hemifield. These results underline the importance of information exchange between the damaged and the healthy hemisphere for possible partial or full recovery from hemianopia.

Neurophysiological Alterations of the Visual Pathway in Posterior Cortical Atrophy: Systematic Review and a Case Series.

Background: The clinical features of posterior cortical atrophy (PCA), a rare condition often caused by Alzheimer's disease, have been recently defined, while little is known about its neurophysiological correlates. Objective: To describe neurophysiological alterations of the visual pathway as assessed using visual field test (VF), visual evoked potentials (VEP), and electroretinogram (ERG) in PCA patients. Methods: Studies reporting VF, VEPs, and ERG in PCA patients were selected according PRISMA method. Of the 323 articles that emerged from the literature, 17 included the outcomes of interest. To these data, we added those derived from a patient cohort enrolled at our clinic. Results: The literature review included 140 patients, half of them (50%) presented with homonymous hemianopia or quadrantanopia. VEPs were available in 4 patients (2 normal findings, 1 decreased amplitude, and 1 increased latency) and ERG in 3 patients (substantially normal findings). Our case series included 6 patients, presenting with homonymous lateral hemianopia in 50% and contralateral cortical atrophy. VEPs showed normal amplitude in 66-83% according to the stimulation check, and increased latency in 67% in absence of myelin damage on MRI. Latency was increased in both eyes in 50% and only on one side in the other 50%. Such alterations were observed in patients with more severe and symmetric atrophy. ERG showed normal findings. Conclusions: Neurophysiological investigations of the visual pathway in PCA are almost absent in literature. Alterations involve both amplitude and latency and can be also monocular. A multiple-point involvement of the optical pathway can be hypothesized.

Pediatric sellar teratoma - Case report and review of the literature.

BACKGROUND: Intracranial teratoma represents a rare neoplasm, occurring predominantly during childhood. Characteristic symptoms depend on the location but are mainly hydrocephalus, visual disturbances, hypopituitarism, and diabetes insipidus. Initial diagnosis can be challenging due to similar radiological features in both teratomas and other lesions such as craniopharyngiomas. Gross total resection is recommended if feasible and associated with a good prognosis. CASE DESCRIPTION: A 10-year-old girl presented with newly diagnosed growth retardation, fatigue, cephalgia and bilateral hemianopia. Further laboratory analysis confirmed central hypothyroidism and hypercortisolism. Cranial magnetic resonance imaging showed a cystic space-occupying lesion in the sellar and suprasellar compartment with compression of the optic chiasm without hydrocephalus present, suspicious of craniopharyngioma. Subsequently, an endonasal endoscopic transsphenoidal near-total tumor resection with decompression of the optic chiasm was performed. During postoperative recovery the patient developed transient diabetes insipidus, the bilateral hemianopia remained unchanged. The patient could be discharged in a stable condition, while hormone replacement for multiple pituitary hormone deficiency was required. Surprisingly, histopathology revealed conspicuous areas of skin with formation of hairs and squamous epithelia, compatible with a mature teratoma. CONCLUSIONS: We present an extremely rare case of pediatric sellar teratoma originating from the pituitary gland and a review of literature focusing on the variation in presentation and treatment. Sellar teratomas are often mistaken for craniopharyngioma due to their similar radiographic appearances. However, the primary goal of treatment for both pathologies is to decompress eloquent surrounding structures such as the optic tract, and if applicable, resolution of hydrocephalus while avoiding damage to the pituitary stalk and especially the hypothalamic structures. If feasible, the aim of surgery should be gross total resection.

Temporal Changes in Cerebral Blood Flow during Migraine with Aura of Alternating Left and Right Homonymous Hemianopsia.

A 16-year-old boy presented with sudden left homonymous hemianopsia followed by right ocular and occipital pain. Arterial spin labeling (ASL), a non-contrast magnetic resonance imaging technique used to evaluate perfusion, showed a decrease in cerebral blood flow in the right occipital lobe. Three hours after admission, the patient experienced right homonymous hemianopsia and ocular-to-occipital pain on the contralateral side. ASL revealed a decreased cerebral blood flow in the left occipital lobe. We ultimately diagnosed the patient with first-time migraine with aura, in which cortical spreading depression was visualized as decreased cerebral blood flow using ASL.