Neuro-ophthalmology

Microglia play a critical role in brain homeostasis and disease progression. In neurodegenerative conditions, microglia acquire the neurodegenerative phenotype (MGnD), whose function is poorly understood. MicroRNA-155 (miR-155), enriched in immune cells, critically regulates MGnD. However, its role in Alzheimer's disease (AD) pathogenesis remains unclear. Here, we report that microglial deletion of miR-155 induces a pre-MGnD activation state via interferon-γ (IFN-γ) signaling, and blocking IFN-γ signaling attenuates MGnD induction and microglial phagocytosis. Single-cell RNA-sequencing analysis of microglia from an AD mouse model identifies Stat1 and Clec2d as pre-MGnD markers. This phenotypic transition enhances amyloid plaque compaction, reduces dystrophic neurites, attenuates plaque-associated synaptic degradation and improves cognition. Our study demonstrates a miR-155-mediated regulatory mechanism of MGnD and the beneficial role of IFN-γ-responsive pre-MGnD in restricting neurodegenerative pathology and preserving cognitive function in an AD mouse model, highlighting miR-155 and IFN-γ as potential therapeutic targets for AD.

Individuals with cerebral visual impairment (CVI) have difficulties identifying common objects, especially when presented as cartoons or abstract images. In this study, participants were shown a series of images of ten common objects, each from five possible categories ranging from abstract black & white line drawings to color photographs. Fifty individuals with CVI and 50 neurotypical controls verbally identified each object and success rates and reaction times were collected. Visual gaze behavior was recorded using an eye tracker to quantify the extent of visual search area explored and number of fixations. A receiver operating characteristic (ROC) analysis was also carried out to compare the degree of alignment between the distribution of individual eye gaze patterns and image saliency features computed by the graph-based visual saliency (GBVS) model. Compared to controls, CVI participants showed significantly lower success rates and longer reaction times when identifying objects. In the CVI group, success rate improved moving from abstract black & white images to color photographs, suggesting that object form (as defined by outlines and contours) and color are important cues for correct identification. Eye tracking data revealed that the CVI group showed significantly greater visual search areas and number of fixations per image, and the distribution of eye gaze patterns in the CVI group was less aligned with the high saliency features of the image compared to controls. These results have important implications in helping to understand the complex profile of visual perceptual difficulties associated with CVI.

BACKGROUND: Optic neuropathy in childhood leukemia occurs through multiple direct and indirect mechanisms, including leukemic infiltration of the optic nerve, infection, blood dyscrasias, or adverse effects of treatment. We aimed to characterize visual outcomes in pediatric patients with leukemia-associated neuro-ophthalmic manifestations. METHODS: We retrospectively identified patients with leukemia and optic nerve pathology over 13 years by diagnostic billing codes. We collected information on demographics, presentation, treatment course, and visual outcomes directly from medical records. RESULTS: Of the 19 patients who met inclusion criteria, 17 (89.5%) had pseudotumor cerebri and 2 had direct optic nerve infiltration. Causes of increased intracranial pressure included central nervous system infiltration (6 of 17), hyperviscosity/leukemia (2 of 17), venous sinus thrombosis (3 of 17), medication induced (5 of 17), and bacterial meningitis (1 of 17). 47.1% (8 of 17) had papilledema at the time of leukemia diagnosis, and 94.1% (16 of 17) of patients with pseudotumor cerebri were treated with acetazolamide. At presentation, 3 patients had decreased vision secondary to macular ischemia, subhyaloid vitreous hemorrhage, or steroid induced glaucoma. Following treatment of pseudotumor cerebri, binocular visual acuity was ≥20/25 in all patients. One patient with optic nerve infiltration had a final visual acuity of count fingers in the affected eye. CONCLUSIONS: In our chart review, the most common mechanism of neuro-ophthalmic involvement in pediatric leukemia was elevated intracranial pressure from a myriad of causes. Visual outcomes from patients with elevated intracranial pressure were excellent. Understanding the mechanisms by which leukemia can cause optic nerve disease in pediatric patients can facilitate earlier diagnosis and treatment and potentially improve visual outcomes.

Despite the high incidence of optic neuritis (ON), and the growing number of therapeutic options for the long-term treatment of diseases associated with ON including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) and MOG antibody associated disease (MOGAD), there are still only limited therapeutic options for treating an acute event of optic neuritis. These include steroids, plasma exchange (PLEX) and intravenous immunoglobulin (IVIG). High-dose steroids remain the mainstay of acute treatment. However, evidence is emerging that when optic neuritis is accompanied with certain atypical features that suggest a more unfavorable outcome this mandates special consideration such as early addition of other therapeutic agents or tapering the steroid very slowly. This review will distinguish between typical and atypical neuritis and discuss acute treatment options.

BACKGROUND: Microcephaly and chorioretinopathy (MCCRP) is a rare autosomal recessive (AR) disorder characterized by microcephaly, developmental delay, chorioretinopathy, and visual impairment. We characterized the long-term phenotype of an additional patient with MCCRP associated with TUBCGP4 pathogenic variants and analysed previously reported cases in the literature. MATERIALS AND METHODS: Analysis of clinical and genetic data of a patient with TUBGCP4-related MCCRP followed for more than 19 years and literature search for previously reported patients with TUBCGP4 variants using PubMed, Scopus, and Google Scholar. RESULTS: Molecular diagnosis using exome sequencing demonstrated two TUBCGP4 variants in trans: c.1669C>T (p.Arg557*) and c.1746 G>T (p.Leu582=). Clinical characteristics included microcephaly, microphthalmia, punched-out chorioretinal lesions, vision impairment, nystagmus, Tetralogy of Fallot and neurodevelopmental delay. Another six previously reported cases of TUBCGP4-related MCCRP were identified. Their clinical and genetic characteristics are compared. CONCLUSIONS: TUBCGP4-related microcephaly and chorioretinopathy, is a rare autosomal recessive neuro-ophthalmic disorder. Clinical characteristics in our proband have remained stable for two decades. The pathophysiology of this syndrome is not yet fully understood.

Neuronal repopulation achieved through transplantation or transdifferentiation from endogenous sources holds tremendous potential for restoring function in chronic neurodegenerative disease or acute injury. Key to the evaluation of neuronal engraftment is the definitive discrimination of new or donor neurons from preexisting cells within the host tissue. Recent work has identified mechanisms by which genetically encoded donor cell reporters can be transferred to host neurons through intercellular material transfer. In addition, labeling transplanted and endogenously transdifferentiated neurons through viral vector transduction can yield misexpression in host cells in some circumstances. These issues can confound the tracking and evaluation of repopulated neurons in regenerative experimental paradigms. Using the retina as an example, we discuss common reasons for artifactual labeling of endogenous host neurons with donor cell reporters and suggest strategies to prevent erroneous conclusions based on misidentification of cell origin.

PURPOSE OF REVIEW: Optical coherence tomography angiography (OCTA) is a novel, noninvasive imaging technique, which provides depth resolved visualization of microvasculature of the retina and choroid. Although OCTA has been widely used for the evaluation of a number of retinal diseases, its use in the field of neuro-ophthalmology has been less studied. In this review, we provide an update on the utility of OCTA in neuro-ophthalmic conditions. RECENT FINDINGS: Peripapillary and macular microvasculature analyses have indicated that OCTA can be a promising tool for early detection of a number of neuro-ophthalmic diseases, differential diagnosis, and monitoring of disease progression. Recent studies have demonstrated that structural and functional impairment can develop at early stages in some conditions such as in multiple sclerosis and Alzheimer's disease even in the absence of overt clinical symptoms. Furthermore, this dye-less technique can be a valuable adjunct tool in the detection of complications commonly seen in some congenital entities such optic disc drusen. SUMMARY: Since its introduction, OCTA has emerged as an important imaging approach shedding light on unrevealed pathophysiological mechanisms of several ocular diseases. The use of OCTA as a biomarker in the field of neuro-ophthalmology has recently gained considerable attention with studies supporting its role in clinical setting while larger studies are warranted for correlating these findings with traditional diagnostic procedures and clinical features and outcomes.

AIM: Using a visual psychophysical paradigm, we sought to assess motion and form coherence thresholds as indices of dorsal and ventral visual stream processing respectively, in individuals with cerebral visual impairment (CVI). We also explored potential associations between psychophysical assessments and brain lesion severity in CVI. METHOD: Twenty individuals previously diagnosed with CVI (mean age = 17 years 11 months [SD 5 years 10 months]; mean Verbal IQ = 86.42 [SD 35.85]) and 30 individuals with neurotypical development (mean age = 20 years 1 month [SD 3 years 8 months]; mean Verbal IQ = 110.05 [SD 19.34]) participated in the study. In this two-group comparison, cross-sectional study design, global motion, and form pattern coherence thresholds were assessed using a computerized, generalizable, self-administrable, and response-adaptive psychophysical paradigm called FInD (Foraging Interactive D-prime). RESULTS: Consistent with dorsal stream dysfunction, mean global motion (but not form) coherence thresholds were significantly higher in individuals with CVI compared to controls. No statistically significant association was found between coherence thresholds and lesion severity. INTERPRETATION: These results suggest that the objective assessment of motion and form coherence threshold sensitivities using this psychophysical paradigm may be useful in helping to characterize perceptual deficits and the complex clinical profile of CVI. WHAT THIS PAPER ADDS: In participants with cerebral visual impairment (CVI), motion (but not form) coherence thresholds were significantly higher compared to controls. These psychophysical results support the notion of dorsal stream dysfunction in CVI.

OBJECTIVE: To provide a retrospective evaluation of a new eye and vision rehabilitation care pathway in a U.S. multi-site inpatient rehabilitation network involving the occupational therapy (OT) staff and a consulting doctor of optometry (OD) specializing in vision rehabilitation. DESIGN: Retrospective study. SETTING: Two Inpatient Rehabilitation Facilities (IRFs) and 1 Long Term Acute Care Hospital (LTACH). PARTICIPANTS: There were 2083 records reviewed (44% women, avg. age 59 years). The most common diagnoses were hemispatial neglect (19.2%), homonymous field defects (18.5%), and oculomotor cranial nerve palsies (16.7%) (N=2083). INTERVENTIONS: Clinical care was reviewed where diagnosis-specific protocols were developed and training was provided to OTs in order to reinforce OD-prescribed interventions during daily treatment sessions, including (1) third, fourth, and sixth ocular cranial nerve palsies (OCNPs) with prisms fitted for full time, postural adaptation training, and oculomotor re-education using pursuits, saccades, head-rotations, and binocular vision exercises including alternate cover and vergence; (2) homonymous hemianopia with training awareness of field loss, eccentric viewing, and fitting of Peli lens for optical field expansion; and (3) prism adaptation therapy (PAT) for left hemispatial neglect. MAIN OUTCOME MEASURES: Frequency of diagnoses. HYPOTHESIS: Diagnoses with developed protocols were most common. Secondarily, feasibility and efficacy by anonymous OT survey. RESULTS: 2083 vision consults were performed over 5 years. The most common diagnoses were hemispatial neglect (n=399, 19.2%), homonymous field defects (n=386, 18.5%), and OCNPs (n=347, 16.7%). None of the OTs reported the protocols were infeasible and 63% (IQR 38%-69%) reported their patients benefited from the interventions. The survey suggested prism for OCNPs helped in 42%, and Peli lens and PAT both helped in 38%. CONCLUSIONS: Data support the feasibility of this inpatient eye and vision rehabilitation care pathway which may be used as a foundation for creating or refining similar programs elsewhere. Uniform administration of IRF-based visual neuro-rehabilitation care could provide a substrate for future clinical trials to evaluate efficacy.

BACKGROUND: Neuro-ophthalmologists have expertise in rare and complex disorders, but the ability of patients to access neuro-ophthalmic care has not been examined at a nationwide level. METHODS: Using the 2020 directory of all 502 members of the North American Neuro-Ophthalmology Society as a reference, we found the practice locations of 461 confirmed practicing members and converted each street address to latitude and longitude coordinates. We calculated the travel distance and time from each census tract to the nearest practice location and calculated population-weighted averages by state, region, and other prespecified factors. Choropleth maps were used to visualize the distribution of travel distances and times across the United States. RESULTS: California had the most practicing neuro-ophthalmologists out of any state (50), whereas 4 states (DE, MT, SD, and WY) had none. Washington, DC and MA had the most neuro-ophthalmologists per capita. The average travel distance and time to the nearest neuro-ophthalmologists were found to be 40.90 miles and 46.50 minutes, respectively, although a large portion of western plains and mountain regions had travel times of over 120 minutes. Patients in rural areas had longer travel times than those in urban areas, and Native American patients had the longest travel times of any racial or ethnic group. CONCLUSION: The travel time to see a neuro-ophthalmologist varies widely by state, region, and rurality, with Native American patients and rural patients being disproportionately affected. By identifying the areas with the greatest travel burdens, future policies can work to alleviate these potential barriers to care.

OBJECTIVE: The head and intraocular trauma tool (HITT) is a portable, binocular retinal polarization scanner (RPS) that detects ocular fixation with high precision to assess visuomotor function. We conducted a pilot evaluation of a prototype binocular RPS device to evaluate alterations in fixation stability, binocularity (convergence), and saccadic latency after mild traumatic brain injury (mTBI). METHODS: Two groups were studied prospectively: (1) single observation study of mTBI patients in a hospital ER (n = 7) and age-matched controls (n = 43); (2) high-school athletes preseason (n = 28), after sports-related mTBI (n = 3), and at season end (n = 5). Subjects were asked to fixate on an internal target and track randomly presented peripheral and central targets as fixation was assessed using binocular RPS. RESULTS: There were clinically and statistically significant alterations in the hospital ER group after mTBI, including a decrease in fixation stability (54.6% in patents vs 90.2% in controls, p = 0.014) and binocularity (28.7% in patients vs 86.6% in controls; p = 0.004). Similar trends, not statistically significant, were observed in saccadic latency in the hospital ER group as well as in the injured high school athletes. CONCLUSION: The HITT device shows promise as an objective, noninvasive method for assessment of the impact of mTBI on visuomotor function. Additional studies with larger patient populations are required to evaluate efficacy for clinical use.

BACKGROUND: Recovery from amblyopia in adulthood after fellow eye (FE) vision loss is a well-known phenomenon. Incidence of recovery varies widely following different FE pathologies, and the rate of recovery after FE ischemic optic neuropathy (ION) has not been examined. We aimed to determine the frequency and degree of improvement in amblyopic eye (AE) visual function after ION in the FE. METHODS: We performed a retrospective chart review of patients between 2007 and 2021 confirmed to have amblyopia and ischemic optic neuropathy in different eyes. Patients with unstable ocular pathology potentially limiting vision were excluded. We compared the best-corrected visual acuity (VA) in each eye before and after FE ION over time. For patients with available data, we examined change in perimetric performance over time. RESULTS: Among the 12 patients who met the inclusion criteria (mean age 67 ± 8 years), 9 (75%) improved ≥1 line and 2 (17%) improved ≥3 lines. The median time from ION symptom onset to maximal improvement was 6 months (range: 2-101 months). Reliable perimetric data were available for 6 patients. Mean sensitivity improved in the AE for all patients, with mean improvement of 1.9 ± 1.1 dB. There was no correspondence between foci of ION-related field loss and gains in field sensitivity in the AE. CONCLUSIONS: A high proportion of patients with amblyopia and contralateral ION experience improvement in AEVA. Modest gains in perimetric sensitivity in the AE may accompany FE ION. These findings support the view that residual plasticity in the adult visual cortex can be tapped to support functional improvement in amblyopia.

BACKGROUND: Absence of hydrocephalus on neuroimaging may impart a false sense of security for patients with pineal cysts. In this case series, we characterize a subset of patients with pineal cysts having an occult presentation. Unifying features of worsening paroxysmal headaches suggesting intermittent obstructive hydrocephalus and radiographic evidence of third ventricular invagination characterize these patients as high risk. OBJECTIVE: To define features of occult, high-risk pineal cysts and outcomes of endoscopic cyst fenestration. METHODS: Charts were retrospectively reviewed for patients with pineal cysts evaluated at our institution between 2018 and 2021 who underwent endoscopic cyst fenestration. To capture cysts presenting as occult, patients were excluded if hydrocephalus was noted at presentation. Relevant clinical history, imaging, operative data, and clinical outcomes were reviewed. RESULTS: Of 50 pineal cyst patients, 4 satisfied inclusion criteria. All patients presented with worsening paroxysmal headaches. In addition, 75% (3/4) also experienced intermittent syncope. Patients exhibited no hydrocephalus (n = 3) or fluctuating ventricular size on longitudinal imaging (n = 1). In all cases, high-resolution sagittal 3-dimensional T2 magnetic resonance imaging demonstrated invagination of the cyst anteriorly into the posterior third ventricle. All patients underwent endoscopic cyst fenestration with complete symptom resolution (mean follow-up of 20.6 months; range 3.5-37.4 months). CONCLUSION: The clinical history for occult, high-risk pineal cysts is notable for worsening paroxysmal headaches and episodic alterations of consciousness suggesting intermittent obstructive hydrocephalus. Because ventricular size can appear normal on standard imaging protocols, clinical suspicion should trigger workup with high-resolution magnetic resonance imaging designed to detect these cysts. Endoscopic cyst fenestration is a safe and efficacious management strategy.

BACKGROUND: Validated methods to identify neuro-ophthalmologists in administrative data do not exist. The development of such method will facilitate research on the quality of neuro-ophthalmic care and health care utilization for patients with neuro-ophthalmic conditions in the United States. METHODS: Using nationally representative, 20% sample from Medicare carrier files from 2018, we identified all neurologists and ophthalmologists billing at least 1 office-based evaluation and management (E/M) outpatient visit claim in 2018. To isolate neuro-ophthalmologists, the National Provider Identifier numbers of neuro-ophthalmologists in the North American Neuro-Ophthalmology Society (NANOS) directory were collected and linked to Medicare files. The proportion of E/M visits with International Classification of Diseases-10 diagnosis codes that best distinguished neuro-ophthalmic care ("neuro-ophthalmology-specific codes" or NSC) was calculated for each physician. Multiple logistic regression models assessed predictors of neuro-ophthalmology specialty designation after accounting for proportion of ophthalmology, neurology, and NSC claims and primary specialty designation. Sensitivity, specificity, and positive predictive value (PPV) for varying proportions of E/M visits with NSC were calculated. RESULTS: We identified 32,293 neurologists and ophthalmologists who billed at least 1 outpatient E/M visit claim in 2018 in Medicare. Of the 472 NANOS members with a valid individual National Provider Identifier, 399 (84.5%) had a Medicare outpatient E/M visit in 2018. The model containing only the proportion of E/M visits with NSC best predicted neuro-ophthalmology specialty designation (odds ratio 1.05 [95% confidence interval 1.04, 1.05]; P < 0.001; area under the receiver operating characteristic [AUROC] = 0.91). Model predictiveness for neuro-ophthalmology designation was maximized when 6% of all billed claims were for NSC (AUROC = 0.89; sensitivity: 84.0%; specificity: 93.9%), but PPV was low (14.9%). The threshold was unchanged when limited only to neurologists billing ≥1% ophthalmology claims or ophthalmologists billing ≥1% neurology claims, but PPV increased (33.3%). CONCLUSIONS: Our study provides a validated method to identify neuro-ophthalmologists who can be further adapted for use in other administrative databases to facilitate future research of neuro-ophthalmic care delivery in the United States.