Stimulus type and duration affect magnitude and evolution of flicker-induced hyperemia measured by laser speckle flowgraphy at the optic disc and peripapillary vessels.

Neurovascular coupling is a vital mechanism employed by the cerebrovascular system, including the eye, to regulate blood flow in periods of neuronal activation. This study aims to investigate if laser speckle flowgraphy (LSFG) can detect coupling response elicited by flickering light stimuli and how variations in stimulus type and duration can affect the magnitude and evolution of blood flow in the optic nerve head (ONH) and peripapillary vessels. Healthy adults were exposed to two types of 10-Hz flicker stimuli: a photopic negative response-like stimulus (PhNR-S) or a visual evoked potential-like stimulus (VEP-S)-each presented in separate 10- and 60-s epochs. Both PhNR-S and VEP-S significantly increased ONH blood flow (p < 0.001) immediately after flicker cessation, with a trend of 60-s stimuli (PhNR-S = 11.6%; VEP-S = 10.4%) producing a larger response than 10-s stimuli (PhNR-S = 7.5%; VEP-S = 6.2%). Moreover, exposure to 60-s stimuli elicited a significantly prolonged ONH hyperemic response, especially with PhNR-S. Lastly, stimulation with either 60-s stimuli elicited a robust increase in blood flow within the peripapillary arterioles (p < 0.01) and venules (p < 0.01) as well. Flicker stimulation with common visual electrophysiology stimuli (PhNR-S and VEP-S) induced a demonstrable increase in ONH and peripapillary vessel blood flow, which varied with flicker duration. Our results validate that LSFG is a robust method to quantify flicker-induced hyperemic responses and to study neurovascular coupling in humans.

The Relationship Between Choroidal Abnormalities and Visual Outcomes in Pediatric Patients With NF1-Associated Optic Pathway Gliomas.

BACKGROUND: Choroidal abnormalities (CAs) visualized on near-infrared reflectance (NIR) imaging are a new diagnostic criterion for neurofibromatosis type 1 (NF1), but the association between the presence of CAs and visual function remains unknown. This study evaluated the relationship between visual acuity (VA) with the presence, number, or total area of CAs visualized by NIR in children with NF1-associated optic pathway gliomas (NF1-OPGs). METHODS: Patients (<18 years) enrolled in a prospective longitudinal study of children with NF1-associated OPGs from 3 institutions were eligible if they had optical coherence tomography (OCT) of the macula (Heidelberg Spectralis) with ≥1 year of follow-up. The central 30° NIR images were reviewed by 2 neuro-ophthalmologists who manually calculated the number and total area of CAs. VA (logMAR) was measured using a standardized protocol. Cross-sectional associations of presence, number, and total area of CAs with VA, retinal nerve fiber layer thickness (RNFL), and ganglion cell-inner plexiform layer thickness were evaluated at the first and most recent visits using regression models. Intereye correlation was accounted for using generalized estimating equations. RESULTS: Eighty-two eyes of 41 children (56% female) were included. The mean ± SD age at the first OCT was 10.1 ± 3.3 years, with a mean follow-up of 20.4 ± 7.2 months. At study entry, CAs were present in 46% of eyes with a mean number of 2.1 ± 1.7 and a mean total area of 2.0 ± 1.7 mm 2 per eye. At the most recent follow-up, CAs were present in 48% of eyes with a mean number of 2.2 ± 1.8 lesions and a mean total area of 2.3 ± 2.1 mm 2 per eye. Neither VA nor OCT parameters at first and follow-up visits were associated with the presence, number, or total area of CAs (all P > 0.05). CONCLUSIONS: CAs are prevalent but not ubiquitous, in children with NF1-OPGs. Although CAs are a diagnostic criterion for NF1, their presence and size do not appear to be associated with visual function.

Comparison of Visual Acuity Results Between ATS-HOTV and E-ETDRS Testing Methods in Children With Optic Pathway Gliomas.

Purpose: To determine if visual acuity (VA) outcomes are comparable using the amblyopia treatment study HOTV protocol (ATS-HOTV) and electronic Early Treatment of Diabetic Retinopathy Study (E-ETDRS) protocol in children with optic pathway gliomas (OPGs). Methods: Children enrolled in a prospective study of OPGs were eligible if they completed both the ATS-HOTV and E-ETDRS during the same visit. The contribution of age, testing order, having neurofibromatosis type 1, visual field loss, and circumpapillary retinal nerve fiber layer thickness to VA difference were assessed using generalized estimating equations to account for the intereye correlation. Results: Forty-eight children (median age, 10.3 years; range, 5.2-17.1 years; 49% female) met inclusion criteria and contributed 93 study eyes at their initial visit. Eleven patients (22 eyes) had more than one study visit, permitting longitudinal evaluation. ATS-HOTV measures of VA were higher than E-ETDRS at the initial (0.13 ± 0.36 vs. 0.23 ± 0.39 logarithm of the minimum angle of resolution [logMAR], P < 0.001) and all visits (0.13 ± 0.34 vs. 0.21 ± 0.36 logMAR, P < 0.001). VA remained significantly higher with ATS-HOTV regardless of test order, but the mean difference between tests was most profound when tested with ATS-HOTV first compared to E-ETDRS first (P < 0.001). Conclusions: VA results differ significantly between the ATS-HOTV and E-ETDRS testing methods in children with OPGs. Given the wide range of ages and testing ability of children, one VA testing method should be used throughout longitudinal OPG clinical trials. Translational Relevance: It is imperative that age-appropriate VA testing methods are standardized across all pediatric OPG clinical trials.

Utility of Ultrasound and Optical Coherence Tomography in Differentiating Between Papilledema and Pseudopapilledema in Children.

BACKGROUND: Differentiating between papilledema and pseudopapilledema in children presenting with mild-to-moderate optic nerve head elevation is challenging. This study sought to determine which B-scan ultrasonography (BSUS) and optical coherence tomography (OCT) features, individually or in combination, are best able to differentiate between papilledema and pseudopapilledema in children. METHODS: Children presenting with optic nerve head elevation of unknown etiology were eligible if they underwent BSUS and OCT performed by the same investigator. The absolute optic nerve sheath diameter (in millimeter) along with the presence/absence of a hyperreflective nodule(s) at the optic nerve head (indicative of druse) from BSUS was determined. The average circumpapillary retinal nerve fiber layer (cpRNFL), diameter of Bruch membrane opening, maximum papillary height, and the presence/absence of hyper-/hyporeflective lesions at the optic nerve head were calculated. Sensitivity and specificity were calculated to evaluate which BSUS and OCT imaging features, individually and in combination, accurately classified children as having papilledema vs pseudopapilledema. RESULTS: One hundred eighty-one eyes from 94 children (mean age, 11.0 years; range, 3.2-17.9) were included; 36 eyes with papilledema and 145 eyes with pseudopapilledema. Among BSUS features, optic nerve sheath widening (>4.5 mm) demonstrated the best sensitivity (86%; 95% confidence interval [CI], 64%-96%) and specificity (88%; 95% CI, 79%-94%) for papilledema. Among OCT measures, cpRNFL thickness of ≥140 µm demonstrated the best sensitivity (83%; 95% CI, 66%-93%) and specificity (76%; 95% CI, 66%-84%) to identify papilledema. The presence of both optic nerve sheath widening (>4.5 mm) and cpRNFL thickness of ≥140 µm reduced the sensitivity (72%; 95% CI, 52%-86%) but increased specificity (95%; 95% CI, 88%-98%). CONCLUSION: BSUS (optic nerve sheath widening [>4.5 mm]) and OCT (cpRNFL thickness ≥140 µm), individually and collectively, have good diagnostic accuracy for differentiating between papilledema and pseudopapilledema. The presence of druse does not exclude the diagnosis of papilledema.