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Featured researches published by Yvonne M. Buys.


Ophthalmology | 2011

Treatment Outcomes in the Ahmed Baerveldt Comparison Study after 1 Year of Follow-up

Donald L. Budenz; Keith Barton; William J. Feuer; Joyce C. Schiffman; Vital Paulino Costa; David G. Godfrey; Yvonne M. Buys

PURPOSE To determine the relative efficacy and complications of the Ahmed glaucoma valve (AGV) model FP7 (New World Medical, Ranchos Cucamonga, CA) and the Baerveldt glaucoma implant (BGI) model 101-350 (Abbott Medical Optics, Abbott Park, IL) in refractory glaucoma. DESIGN Multicenter, randomized, controlled clinical trial. PARTICIPANTS Two hundred seventy-six patients, including 143 in the AGV group and 133 in the BGI group. METHODS Patients 18 to 85 years of age with refractory glaucoma having intraocular pressure (IOP) of 18 mmHg or more in whom an aqueous shunt was planned were randomized to undergo implantation of either an AGV or a BGI. MAIN OUTCOME MEASURES The primary outcome was failure, defined as IOP >21 mmHg or not reduced by 20% from baseline, IOP ≤5 mmHg, reoperation for glaucoma or removal of implant, or loss of light perception vision. Secondary outcomes included mean IOP, visual acuity, use of supplemental medical therapy, and complications. RESULTS Preoperative IOP (mean±standard deviation [SD]) was 31.2±11.2 mmHg in the AGV group and 31.8±12.5 mmHg in the BGI group (P = 0.71). At 1 year, mean±SD IOP was 15.4±5.5 mmHg in the AGV group and 13.2±6.8 mmHg in the BGI group (P = 0.007). The mean±SD number of glaucoma medications was 1.8±1.3 in the AGV group and 1.5±1.4 in the BGI group (P = 0.071). The cumulative probability of failure was 16.4% (standard error [SE], 3.1%) in the AGV group and 14.0% (SE, 3.1%) in the BGI group at 1 year (P = 0.52). More patients experienced early postoperative complications in the BGI group (n = 77; 58%) compared with the AGV group (n = 61; 43%; P = 0.016). Serious postoperative complications associated with reoperation, vision loss of ≥2 Snellen lines, or both occurred in 29 patients (20%) in the AGV group and in 45 patients (34%) in the BGI group (P = 0.014). CONCLUSIONS Although the average IOP after 1 year was slightly higher in patients who received an AGV, there were fewer early and serious postoperative complications associated with the use of the AGV than the BGI.


Ophthalmology | 1992

Retinal findings after head trauma in infants and young children.

Yvonne M. Buys; Alex V. Levin; Robert W. Enzenauer; James E. Elder; Mary A. Letourneau; Robin P. Humphreys; Marcellina Mian; J. Donald Morin

BACKGROUND Many authorities believe that the finding of retinal hemorrhages in a child younger than 3 years of age with a history of head trauma, in the absence of an obvious cause for the injury, is pathognomonic of child abuse. To date, no studies have examined the prospective retinal examination of children who have had head trauma. The authors undertook such a study because the presence of retinal hemorrhage from any head trauma in children may have medicolegal diagnostic significance in differentiating accidental from nonaccidental trauma. METHODS Seventy-nine children younger than 3 years of age, each of whom experienced head injury, underwent an ophthalmologic assessment, which included a dilated funduscopic examination. RESULTS Seventy-five children sustained accidental head injuries and had normal funduscopic examinations. Three children had nonaccidental head injuries and all were found to have varying degrees of retinal hemorrhages. One child, with a normal fundus examination, had injuries that were of indeterminate cause. CONCLUSION The finding of retinal hemorrhages in a child with a head injury suggests a nonaccidental cause.


Survey of Ophthalmology | 2013

Intraocular Pressure Monitoring Post Intravitreal Steroids: A Systematic Review

Weerawat Kiddee; Graham E. Trope; Lisa Sheng; Laura Beltran-Agullo; Michael Smith; M. Hermina Strungaru; Jasrajbir S. Baath; Yvonne M. Buys

The use of intravitreal (IVT) corticosteroids for treatment of posterior segment diseases has increased significantly over the last decade. A commonly recognized complication of IVT steroids is secondary ocular hypertension (OHT) that can occur immediately secondary to direct intraocular volume increase or weeks to months later as a result of increased outflow resistance. We performed a meta-analysis and found 32% (95% confidence interval, 28.2-36.3) of individuals developed OHT following 4 mg IVT triamcinolone, 66% (50.2-78.8) and 79% (72.2-84.5) following 0.59 and 2.1 mg fluocinolone implant, respectively, and 11% (6.4-17.9) and 15% (9.2-24.3) following 0.35 and 0.7 mg dexamethasone implant, respectively. Risk factors included pre-existing glaucoma, higher baseline intraocular pressure (IOP), younger age, OHT following previous injection, uveitis, higher steroid dosage, and fluocinolone implant. Most cases of OHT can be controlled medically; up to 45% following fluocinolone implant require surgery, however. We suggest a protocol to monitor IOP after IVT steroid injection/implantation that includes checking IOP within 30 minutes after injection, followed by 1 week after IVT triamcinolone and 2 weeks after implant insertion, then every 2 weeks for the first month and monthly for up to 6 months after IVT triamcinolone and dexamethasone implantation and 9 months after fluocinolone implantation.


Ophthalmology | 2014

Three-year Treatment Outcomes in the Ahmed Baerveldt Comparison Study

Keith Barton; William J. Feuer; Donald L. Budenz; Joyce C. Schiffman; Vital Paulino Costa; David G. Godfrey; Yvonne M. Buys

PURPOSE To compare 3-year outcomes and complications of the Ahmed FP7 Glaucoma Valve (AGV) (New World Medical, Cucamonga, CA) and the Baerveldt Glaucoma Implant (BGI) 101-350 (Abbott Medical Optics, Abbott Park, IL) for the treatment of refractory glaucoma. DESIGN Multicenter, randomized, controlled clinical trial. PARTICIPANTS A total of 276 patients: 143 in the AGV group and 133 in the BGI group. METHODS Patients aged 18 to 85 years with refractory glaucoma and intraocular pressures (IOPs) ≥ 18 mmHg in whom an aqueous shunt was planned were randomized to an AGV or a BGI. MAIN OUTCOME MEASURES The IOP, visual acuity (VA), supplemental medical therapy, complications, and failure (IOP >21 mmHg or not reduced by 20% from baseline, IOP <5 mmHg, reoperation for glaucoma or removal of implant, or loss of light perception vision). RESULTS At 3 years, IOP (mean ± standard deviation) was 14.3 ± ± 4.7 mmHg (AGV group) and 13.1 ± 4.5 mmHg (BGI group) (P = 0.086) on 2.0 ± 1.4 and 1.5 ± 1.4 glaucoma medications, respectively (P = 0.020). The cumulative probabilities of failure were 31.3% (standard error [SE], 4.0%) (AGV) and 32.3% (4.2%) (BGI) (P = 0.99). Postoperative complications associated with reoperation or vision loss of >2 Snellen lines occurred in 24 patients (22%) (AGV) and 38 patients (36%) (BGI) (P = 0.035). The mean change in the logarithm of the minimum angle of resolution VA at 3 years was similar (AGV: 0.21 ± 0.88, BGI: 0.26 ± 0.74) in the 2 treatment groups at 3 years (P = 0.66). The cumulative proportion of patients (SE) undergoing reoperation for glaucoma before the 3-year postoperative time point was 14.5% (3.0%) in the AGV group compared with 7.6% (2.4%) in the BGI group (P = 0.053, log rank). The relative risk of reoperation for glaucoma in the AGV group was 2.1 times that of the BGI group (95% confidence interval, 1.0-4.8; P = 0.045, Cox proportional hazards regression). CONCLUSIONS Implantation of the AGV was associated with the need for significantly greater adjunctive medication to achieve equal success relative to implantation of the BGI and resulted in a greater relative risk of reoperation for glaucoma. More subjects experienced serious postoperative complications in the BGI group than in the AGV group.


American Journal of Ophthalmology | 1999

Ultrasound biomicroscopic quantitative analysis of light-dark changes associated with pupillary block

Elaine K Woo; Charles J. Pavlin; Alan Slomovic; Nathan Taback; Yvonne M. Buys

PURPOSE To quantitatively analyze the changes in anterior chamber angle and iris configuration induced by varying illumination in patients with narrow angles and pupillary block. METHODS Twenty-four eyes of 24 patients with pupillary block (mean age, 52.5 years) had ultrasound biomicroscopic images of the angle and iris structures obtained superiorly, nasally, inferiorly, and temporally. Images were performed in the light and the dark. We measured the angle opening distance, iris thickness, iris chord length, iris-lens touch, and iris curvature. RESULTS Changes in iris and angle configuration occurred within a few seconds of a change in lighting. The mean dark measurements were statistically significantly less than the mean light measurements for angle opening distance (96 +/- 18 vs 185 +/- 26 microm, P = .0001), iris chord length (2,505 +/- 61 vs 3,001 +/- 69 microm, P = .0001), and iris-lens touch (350 +/- 20 vs 693 +/- 35 microm, P = .0001). The mean dark measurements were statistically significantly greater than the mean light measurements for iris thickness at 500 microm from the scleral spur (367 +/- 10 vs 307 +/- 25 microm, P = .0001), and 1,500 microm from the scleral spur (404 +/- 14 vs 347 +/- 12 microm, P = .0001). Iris curvature in all four quadrants was statistically significantly greater in the dark than the light. CONCLUSIONS This study quantitatively confirms that angle narrowing in the dark in eyes with pupillary block is associated with iris shortening, increased iris thickness, and increased iris convexity. Iris-lens touch is relatively small in pupillary block and decreases with dilation. Angle narrowing with dilation is not related to increased iris-lens touch and occurs promptly without requiring time for aqueous pressure buildup behind the iris.


Journal of Glaucoma | 2003

Cost of glaucoma in Canada: analyses based on visual field and physician's assessment.

Michael Iskedjian; John H. Walker; Colin Vicente; Graham E. Trope; Yvonne M. Buys; Thomas R. Einarson; David Covert

PurposeA longitudinal, retrospective study investigated the cost of primary open angle glaucoma (POAG). MethodsPatient files from two tertiary care glaucoma practices were reviewed. Patients diagnosed with POAG and ≥2.5 years of follow-up data were included. Data collected included visual field mean deviation, physicians assessment, and resource utilization (physician visits, procedures, and medications). Costs, reported in 2001 Canadian dollars, were compared between groups, based on initial visual field mean deviation, including mild (<5 dB), moderate (5 to <12 dB), and severe (≥12 dB), and based on physicians assessment, including controlled, uncontrolled, or patients initially uncontrolled for 12 months who become controlled. ResultsOf 411 patient charts extracted, 265 were included; 35 were excluded for ocular comorbidities and 111 patients with insufficient follow-up. Mean (standard deviation) yearly costs overall (N = 265) and for mild (n = 90), moderate (n = 91), and severe (n = 84) groups were


Ophthalmology | 1993

Prospective Study of Sub-Tenon's versus Retrobulbar Anesthesia for Inpatient and Day-surgery Trabeculectomy

Yvonne M. Buys; Graham E. Trope

508 (


Journal of Glaucoma | 2006

Laser trabeculoplasty trends with the introduction of new medical treatments and selective laser trabeculoplasty.

Rony Rachmiel; Graham E. Trope; Mary Chipman; Peter Gouws; Yvonne M. Buys

278),


Ophthalmology | 2010

Effect of Sleeping in a Head-Up Position on Intraocular Pressure in Patients with Glaucoma

Yvonne M. Buys; Tariq Alasbali; Ya-Ping Jin; M. Smith; Pieter Gouws; Noa Geffen; John G. Flanagan; Colin M. Shapiro; Graham E. Trope

408 (


Canadian Journal of Ophthalmology-journal Canadien D Ophtalmologie | 2008

Ahmed glaucoma valve implantation in uveitic glaucoma versus open-angle glaucoma patients.

Rony Rachmiel; Graham E. Trope; Yvonne M. Buys; John G. Flanagan; Mary Chipman

266),

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Rony Rachmiel

Toronto Western Hospital

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