Kameran Lashkari

Purpose Delayed Dark-Adapted vision Recovery (DAR) is a known biomarker for Age-related Macular Degeneration (AMD); however, its measurement is often cumbersome for both patients and examiners. In this study, we developed NeuroVEP, a portable, wireless, and user-friendly system designed to objectively assess Dark-Adapted Visual Evoked Potentials (DAVEP). Methods NeuroVEP consists of a headset with a smartphone that delivers controlled photo-bleach and monocular pattern reversal stimuli while utilizing custom electroencephalography (EEG) electrodes and electronics to measure DAVEP. The system allows for separate analysis of the near peripheral and macular visual field of each eye, completing the test in a comfortable, single-session format (Results The algorithm demonstrated: 86% accuracy in early-stage AMD detection (Healthy vs. Early AMD) (Sensitivity: 97%, Specificity: 65%, AUC-ROC: 0.81 and AUC-PR: 0.92) and 93% accuracy in overall AMD detection (Healthy vs. All AMD stages) (Sensitivity: 98%, Specificity: 65%, AUC-ROC: 0.82 and AUC-PR: 0.97). Conclusions We successfully developed a portable, objective user-friendly VEP system and an advanced Bayesian-GMM statistical analysis framework capable of identifying DAR deficits in AMD patients. This novel technology shows high potential for early AMD detection and could serve as a non-invasive, objective diagnostic tool for AMD screening in clinical and remote settings.

Delayed Dark Adapted vision Recovery (DAR) is a biomarker for Age-related Macular Degeneration (AMD), however its measurement is burdensome for patients and examiners. We developed a portable, wireless, quick-setup system that employs a headset with a smartphone to deliver controlled photobleach and monocular pattern reversal stimuli, while using custom electroencephalography (EEG) electrodes and electronics in order to measure objective Dark Adapted Visual Evoked Potentials (DAVEP) at multiple locations of the visual field - all in one comfortable 20-minute session, without requiring subject reporting. DAVEP responses post photobleach (up to 15 minutes), were measured concurrently in both eyes of 13 patients with AMD and 8 others not diagnosed with AMD. New, unexpected features at high latencies were observed in the DAVEP responses to scotopic stimulus intensities. The amplitude recovery of the DAVEP response was significantly delayed in AMD patients compared with controls. We developed DAVEP1 scores, a simple metric for DAR, using it to successfully identify all 100% of AMD subjects and classify 90% of subject eyes correctly. Deficits in DAR in patients with AMD can be identified using this objective VEP based system and the DAVEP1 metric, a promising new objective biomarker for this disease that can be easily tested in a clinic.

Activation of the alternative complement cascade has been implicated in the pathogenesis of age related macular degeneration (AMD) and Alzheimer’s disease (AD). Amyloid β (Aβ), a component of drusen, may promote complement activation by inhibiting CFI bioactivity. We determined whether Aβ reduced CFI bioactivity and whether antibodies against Aβ including a monoclonal antibody, GSK933776 could restore CFI bioactivity. We also measured CFI bioactivity in plasma of subjects with AMD and AD. In support of the GSK933776 development program in AMD (geographic atrophy), we developed a quantitative assay to measure CFI bioactivity based on its ability to cleave C3b to iC3b, and repeated it in presence or absence of Aβ and anti-Aβ antibodies. Using this assay, we measured CFI bioactivity in plasma of 194 subjects with AMD, and in samples from subjects with AD that had been treated with GSK933776 as part of the GSK933776 development program in AD. Aβ reduced the CFI bioactivity by 5-fold and pre-incubation with GSK933776 restored CFI bioactivity. In subjects with AMD, plasma CFI levels and bioactivity were not significantly different from non-AMD controls. However, we detected a positive linear trend, suggesting increasing activity with disease severity. In subjects with AD, we observed a 10% and 27% increase in overall CFI bioactivity after treatment with GSK933776 during the second and third dose. Our studies indicate that CFI enzymatic activity can be inhibited by Aβ and be altered in proinflammatory diseases such as AMD and AD, in which deposition of Aβ and activation of the alternative complement cascade are believed to play a key role in the disease process.

Purpose: Choroidal neovascularization (CNV) is a major cause of visual loss with age-related macular degeneration (AMD). We evaluated whether blockade of phosphatidyl-inositol-3-kinase (PI3K) and the mammalian target of rapamycin (mTOR), by impairing VEGF-A and other growth factor receptors like platelet-derived growth factor (PDGF), would reduce laser-induced CNV in mice. Methods: Choroidal neovascularization lesions were induced in C57BL/6 mice. Two groups of mice received oral GSK2126458 (3 mg/kg) or vehicle for 14 days following laser, whereas three groups were treated with GSK2126458 (6 μg/eye), aflibercept (2 μL/eye), or vehicle intravitreally on days 0 and 7 after laser. Vascular leakage was measured by fluorescein angiography (FA) on day 14. Choroidal neovascularization membranes were evaluated on choroidal flat mounts following FITC–dextran perfusion, as well as ED1 and isolectin B4 (IB4) immunohistochemistry. Results: Oral and intravitreal (IVT) GSK2126458 reduced leakage and area of CNV lesions. Greater probability of leaking lesions (∼60%; P < 0.05) was observed in both vehicle groups. Fluorescein isothiocyanate-dextran–labeled total CNV burden area (total lesion area/eye) was reduced ∼67% (P < 0.05) and 35% (P = 0.0528) after oral and IVT GSK2126458 administration. GSK2126458 treatment reduced lesion size by ∼80% (P < 0.05) and 50% (P < 0.05) for oral and IVT control groups. Aflibercept did not alter lesion size (∼27% reduction). Conclusions: Phosphatidyl-inositol-3-kinase/mTOR is involved in laser-induced CNV angiogenic processes. GSK2126458 effectively reduces CNV size and leakage. Choroidal neovascularization size following IVT GSK2126458 was smaller than after oral administration. Therefore, inhibition of PI3K/mTOR pathways may be more effective due to blockade of action of multiple growth factors.

Purpose: To characterize the angiogenic and inflammatory vitreous biomarker profiles in a spectrum of ischemic retinopathies, including neovascular glaucoma. Methods: This institutional review board–approved study retrospectively analyzed 80 undiluted vitreous samples obtained during pars vitrectomy. The specimens were frozen (−80°C) and sent for concentration analysis of 34 proteins by Bio-Plex Pro assays. Specimens were divided into four groups: patients undergoing epiretinal membrane (ERM) peeling and/or macular hole (MH) surgery with no history of diabetes (non-DM group), patients undergoing ERM peeling, and/or MH surgery with a history of diabetes (DM group), patients with proliferative diabetic retinopathy (PDR group), and patients with neovascular glaucoma (NVG group). Parametric and nonparametric analyses of demographics and cytokine levels were performed using SPSS. Results: There were no significant differences in demographics among cohorts. Numerous proteins were significantly elevated between non-DM and DM (G-CSF, sCD40L, Endoglin, IL-6, placental growth factor [PlGF], VEGF-D), DM and PDR (leptin, IL-8, PlGF, VEGF-A), and PDR and NVG (G-CSF, leptin, TIE-2, sCD40L, EGF, HB-EGF, IL-6, IL-8, PlGF, TNF-α). Only PlGF was significantly elevated between each successive cohort. The most potent drivers of NVG were PlGF, VEGF-A, IL-6, and IL-8. Conclusions: While the role of angioproliferative growth factors is well documented in ischemic retinopathy, our study delineates the importance of inflammatory and previously underreported angiogenic proteins. It also demonstrates a significant incremental increase in certain factors with increasing levels of ischemia. Both of these findings may guide the development of future therapies for ischemic retinopathies.

We have previously characterized human neuronal progenitor cells (hNP) that can adopt a retinal ganglion cell (RGC)-like morphology within the RGC and nerve fiber layers of the retina. In an effort to determine whether hNPs could be used a candidate cells for targeted delivery of neurotrophic factors (NTFs), we evaluated whether hNPs transfected with an vector that expresses IGF-1 in the form of a fusion protein with tdTomato (TD), would increase RGC survival in vitro and confer neuroprotective effects in a mouse model of glaucoma. RGCs co-cultured with hNP^IGF-TD cells displayed enhanced survival, and increased neurite extension and branching as compared to hNP^TD or untransfected hNP cells. Application of various IGF-1 signaling blockers or IGF-1 receptor antagonists abrogated these effects. In vivo, using a model of glaucoma we showed that IOP elevation led to reductions in retinal RGC count. In this model, evaluation of retinal flatmounts and optic nerve cross sections indicated that only hNP^IGF-TD cells effectively reduced RGC death and showed a trend to improve optic nerve axonal loss. RT-PCR analysis of retina lysates over time showed that the neurotrophic effects of IGF-1 were also attributed to down-regulation of inflammatory and to some extent, angiogenic pathways. This study shows that neuronal progenitor cells that hone into the RGC and nerve fiber layers may be used as vehicles for local production and delivery of a desired NTF. Transplantation of hNP^IGF-TD cells improves RGC survival in vitro and protects against RGC loss in a rodent model of glaucoma. Our findings have provided experimental evidence and form the basis for applying cell-based strategies for local delivery of NTFs into the retina. Application of cell-based delivery may be extended to other disease conditions beyond glaucoma.

Purpose: Patients with macular disease often report experiencing metamorphopsia (visual distortion). Although typically measured with Amsler charts, more objective and quantitative assessments of perceived distortion are desirable to effectively monitor the presence, progression and remediation of visual impairment. Methods: Participants with binocular (n = 33) and monocular (n= 50) maculopathy across seven disease groups, and control participants (n = 10) with no identifiable retinal disease completed a modified Amsler Grid assessment (presented on a computer screen with eye tracking to ensure fixation compliance) and two novel objective measures of metamorphopsia in the central five degrees of visual field. 81% (67/83) of participants completed a task requiring them to configure eight dots in the shape of a square, and 64% (32/50) of participants experiencing monocular distortion completed a spatial alignment task using dichoptic stimuli. 10 controls completed all tasks. Results: Horizontal and vertical distortion magnitudes were calculated for each of the three assessments. Distortion magnitudes were significantly higher in patients than controls in all assessments. There was no significant difference in magnitude of distortion across different macular diseases. Among patients, there were no significant correlations between overall magnitude of distortion among any of the three measures and no significant correlations in localized measures of distortion. Conclusions: Three alternative quantifications of monocular spatial distortion in the central visual field generated uncorrelated estimates of visual distortion. It is therefore unlikely that metamorphopsia is caused solely by displacement of photoreceptors in the retina, but instead involves additional top-down information, knowledge about the scene, and perhaps, cortical reorganization.