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Ira Schachar, MD

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Especialidades médicas y/o especialidades quirúrgicas

Ophthalmology

Trabajo y educación

Educación

Washington Univ School Of Med, St. Louis, MO, 05/21/2010

Primeros años de residencia

Brigham and Women's Hospital Harvard Medical School, Boston, MA, 06/30/2011

Últimos años de residencia

University of Michigan Ophthalmology Residency, Ann Arbor, MI, 06/30/2014

Subespecialidad

Stanford Health Services - Ophthalmology, *Stanford, CA, 06/30/2016

Certificado(s) de especialidad

Ophthalmology, American Board of Ophthalmology

Servicios

Ojos y vista

Todo Publicaciones

Surgical timing and presence of a vitreoretinal fellow on postoperative adverse events following pars plana vitrectomy. European journal of ophthalmology Shields, R. A., Ludwig, C. A., Powers, M. A., Tijerina, J. D., Schachar, I. H., Moshfeghi, D. M. 2018: 1120672118811980

Abstract

INTRODUCTION:: To evaluate the adverse event rate following pars plana vitrectomy as a function of surgical start time and the presence of a vitreoretinal fellow.METHODS:: Single-institution retrospective cohort study of patients undergoing pars plana vitrectomy from 1 January 2016 to 31 December 2016 at Stanford University School of Medicine (Palo Alto, CA, USA). Records were reviewed for surgical start time, the presence of vitreoretinal fellow, and postoperative adverse events defined as any finding deviating from the expected postoperative course requiring observation or intervention.RESULTS:: A total of 310 pars plana vitrectomies were performed. There was no statistical difference in the rate of any adverse event when comparing cases starting after 16:01 (9/13, 69.2%) and after 12:01 (42/99, 42.4%) to a morning start time (69/198, 34.9%, adjusted p=0.083). There was a statistically significant increase in the risk of postoperative vitreous hemorrhage with afternoon and evening cases as compared to morning cases (adjusted p=0.021). In addition, there was no difference in any adverse event with a fellow present (93/244, 38.1%) compared to without (27/66, 40.9%, adjusted p=0.163). There was a higher risk of postoperative hypotony when a fellow was involved (6.6% vs 0%, p=0.028), though this difference disappeared after adjusting for confounders (adjusted p=0.252). There was no difference in the length of surgery with and without a fellow (49 vs 54min, respectively; p=0.990).DISCUSSION:: Afternoon start time and the presence of a fellow were not independent risk factors for postoperative adverse events.

View details for PubMedID 30426767

A spectrum of regression following intravitreal bevacizumab in retinopathy of prematurity. American journal of ophthalmology Chen, T. A., Shields, R. A., Bodnar, Z. H., Callaway, N., Schachar, I. H., Moshfeghi, D. M. 2018

Abstract

PURPOSE: To describe an improved understanding of the regression patterns following off-label intravitreal bevacizumab (IVB) treatment for retinopathy of prematurity (ROP).DESIGN: Retrospective cohort study. MethodsAll infants treated with IVB for Type 1 ROP at a single institution from June 2013 to March 2018 were retrospectively reviewed and the amount of retinal non-perfusion on fluorescein angiogram was calculated. ResultsOnly 3 eyes (3.3%) reached full vascular maturity in the 92 eyes of 46 patients analyzed. Of the 89 eyes not reaching maturity, 39 eyes (43.8%) had vascular arrest alone (VAA), 34 eyes (38.2%) had vascular arrest with persistent tortuosity (VAT), and 16 (18.0%) had ROP reactivation. Those eyes that reactivated were more likely to be initially classified as aggressive posterior ROP (p = 0.004) and of Asian ethnicity (p = 0.008). There were greater areas of ischemia in eyes with reactivation as compared to VAT and VAA (112.1 mm2 vs 72.5 mm2 vs. 56.6 mm2, respectively, p = 0.007). Younger gestational age at birth was found to be an independent predictor of persistent tortuosity (VAT vs. VAA) in a logistic regression model. ConclusionsIncomplete vascularization following IVB is very common and is associated with a younger gestational age at birth, Asian ethnicities, and aggressive posterior ROP. The presence of tortuosity following IVB may be indicative of persistently elevated VEGF levels and an early indicator of potential reactivation.

View details for PubMedID 30312578

Progressive Reductions in Acuity Occur even within the First Three Days After a Macula-Off Retinal Detachment Greven, M., Leng, T., Leung, L., Moshfeghi, D. M., Sanislo, S., Silva, R., Schachar, I. ASSOC RESEARCH VISION OPHTHALMOLOGY INC. 2018
Mechanisms of electrical vasoconstriction JOURNAL OF NEUROENGINEERING AND REHABILITATION Brinton, M., Mandel, Y., Schachar, I., Palanker, D. 2018; 15: 43

Abstract

Electrical vasoconstriction is a promising approach to control blood pressure or restrict bleeding in non-compressible wounds. We explore the neural and non-neural pathways of electrical vasoconstriction in-vivo.Charge-balanced, asymmetric pulses were delivered through a pair of metal disc electrodes. Vasoconstriction was assessed by measuring the diameter of rat saphenous vessels stimulated with low-voltage (20V, 1ms) and high-voltage (150V, 10s) stimuli at 10Hz for 5min. Activation pathways were explored by topical application of a specific neural agonist (phenylephrine, alpha-1 receptor), a non-specific agonist (KCl) and neural inhibitors (phenoxybenzamine, 25mg/ml; guanethidine, 1mg/ml). Acute tissue damage was assessed with a membrane permeability (live-dead) fluorescent assay. The Joule heating in tissue was estimated using COMSOL Multiphysics modeling.During stimulation, arteries constricted to 418% and 376% of their pre-stimulus diameter with low- and high-voltage stimuli, while veins constricted to 8018% and 4011%, respectively. In arteries, despite similar extent of constriction, the recovery time was very different: about 30s for low-voltage and 10min for high-voltage stimuli. Neural inhibitors significantly reduced low-voltage arterial constriction, but did not affect high-voltage arterial or venous constriction, indicating that high-voltage stimuli activate non-neural vasoconstriction pathways. Adrenergic pathways predominantly controlled low-voltage arterial but not venous constriction, which may involve a purinergic pathway. Viability staining confirmed that stimuli were below the electroporation threshold. Modeling indicates that heating of the blood vessels during stimulation (<0.2C) is too low to cause vasoconstriction.We demonstrate that low-voltage stimuli induce reversible vasoconstriction through neural pathways, while high-voltage stimuli activate non-neural pathways, likely in addition to neural stimulation. Different stimuli providing precise control over the extent of arterial and venous constriction as well as relaxation rate could be used to control bleeding, perfusion or blood pressure.

View details for PubMedID 29843762

Outcomes of Intravitreal Bevacizumab and Diode Laser Photocoagulation for Treatment-Warranted Retinopathy of Prematurity OPHTHALMIC SURGERY LASERS & IMAGING RETINA Chen, T. A., Schachar, I. H., Moshfeghi, D. M. 2018; 49 (2): 12631

Abstract

To investigate the outcomes of infants with treatment-warranted retinopathy of prematurity (TW-ROP) who received intravitreal bevacizumab (Avastin; Genentech, South San Francisco, CA) (IVB) injections as compared to diode laser photocoagulation (DLP).Data from the Stanford University Network for Diagnosis of Retinopathy of Prematurity database and inpatients at Stanford Children's Hospital were retrospectively reviewed for premature newborns with TW-ROP treated with DLP or 0.625 mg of IVB. Patient characteristics, hospital course, and neurodevelopmental outcomes were compared.In all, 49 eyes from 25 patients were included; 10 infants (20 eyes) received DLP and 15 infants (29 eyes) received IVB. The IVB infants had significantly fewer diagnoses at the time of discharge and fewer readmissions after initial hospital discharge than the DLP infants (four versus six diagnoses, P = .004; zero versus one readmission, P = .038). At an average of 20 months corrected age, there was no significant difference in neurodevelopmental delay (adjusted odds ratio = 0.87; 95% CI, 0.08-9.46).Systemic morbidity may be similar among infants treated initially with bevacizumab compared to DLP. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:126-131.].

View details for DOI 10.3928/23258160-20180129-07

View details for Web of Science ID 000425848800007

View details for PubMedID 29443362

Chronic Vascular Arrest as a Predictor of Bevacizumab Treatment Failure in Retinopathy of Prematurity. Ophthalmology Toy, B. C., Schachar, I. H., Tan, G. S., Moshfeghi, D. M. 2016; 123 (10): 2166-2175

Abstract

To describe a pattern of retinopathy of prematurity (ROP) disease regression and chronic vascular arrest after intravitreal bevacizumab treatment that is not observed after peripheral laser ablation.Single-institution retrospective cohort study.Consecutive sample of 58 eyes in 30 patients treated for type 1 ROP.Initial treatment with either a single intravitreal injection of bevacizumab in off-label use (n= 33 eyes) or peripheral laser ablation (n= 25 eyes) as part of standard clinical care. There was bias in recommending off-label bevacizumab for smaller infants with type 1 ROP.Reactivation or persistence of ROP, as determined by clinical examination, fundus photography, and fluorescein angiography.All eyes treated initially with bevacizumab demonstrated irregular progression of the leading vascular edge in a stereotyped pattern, suggestive of scalloped regression. Recurrence, based on angiographic demonstration of leakage, or chronic vascular arrest, confirmed based on angiographic demonstration of peripheral ischemia, was noted in 30 eyes (91%) in the bevacizumab group, at a median interval of 14.9 weeks after injection (corrected gestational age, 49.3 weeks). Univariate logistic regression indicated that the need for rescue treatment was associated with decreased birth weight (odds ratio [OR],-0.007; P= 0.04) and age of initial treatment (OR,-0.35; P= 0.05), but not gender, race, or gestational age. Multivariate logistic regression indicated that only decreased birth weight (OR,-0.018; P= 0.04) was associated with need for rescue treatment.Treating ROP with intravitreal bevacizumab results in a characteristic scalloped regression pattern that is highly associated with treatment using biologic anti-vascular endothelial growth factor agents. The presence of this pattern in conjunction with chronic vascular arrest and peripheral retinal ischemia persisting beyond standard screening timelines has significant implications for the management of ROP. Fluorescein angiography is important in assessing vascular maturation in these infants.

View details for DOI 10.1016/j.ophtha.2016.06.055

View details for PubMedID 27506484

Multi-Modal Longitudinal Evaluation of Subthreshold Laser Lesions in Human Retina, Including Scanning Laser Ophthalmoscope-Adaptive Optics Imaging. Ophthalmic surgery, lasers & imaging retina Wood, E. H., Leng, T., Schachar, I. H., Karth, P. A. 2016; 47 (3): 268-275

Abstract

Subthreshold retinal laser therapy is efficacious for a variety of retinovascular disorders. Currently, it is unknown which laser parameters can ensure no detectable damage to human retina tissue.One informed physician participant with a normal retina was treated with three levels (75%, 50%, and 25%) of subthreshold 577-nm laser (PASCAL; Topcon, Santa Clara, CA) at 20-millisecond (ms) duration and 100 m spot size. Several high-resolution retinal imaging modalities, including spectral-domain optical coherence tomography (SD-OCT) and scanning laser ophthalmoscope-adaptive optics (SLO-AO), were used to longitudinally image retinal laser lesions during a 9-month period.SLO-AO and SD-OCT imaging of subthreshold laser therapy in human retina showed no cone cell or RPE damage at all time points during a 9-month period using the 25% threshold power 577-nm laser in the human retina.It is likely that subthreshold laser therapy with 577-nm laser at 20-ms duration in the human retina is safe at the 25% of threshold power level. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:268-275.].

View details for DOI 10.3928/23258160-20160229-10

View details for PubMedID 26985801