Catherine M. Birt
University of Toronto
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Featured researches published by Catherine M. Birt.
Journal of Glaucoma | 2013
Corey Boimer; Catherine M. Birt
Purpose:To study the impact of benzalkonium chloride (BAK) exposure from eye drops on subsequent time to trabeculectomy failure. Patients and Methods:Retrospective chart review of 128 glaucoma patients who had undergone a trabeculectomy between 2004 and 2006. The number and type of ophthalmic drops used preoperatively and relevant demographics were recorded. Surgical failure criteria included inadequate pressure lowering or need for postoperative ocular antihypertensives, laser trabeculoplasty, 5-fluorouracil needling, or repeated surgery. Patients were examined for these criteria over a minimum postoperative period of 2 years. Data were assessed using Kaplan-Meier and Cox regression models. Results:Complete surgical success was achieved in 47.7% of patients. Patients received between 1 and 8 BAK-containing drops daily, with a median of 3. Time to surgical failure in patients receiving higher preoperative daily doses of BAK was shorter than in patients who had less BAK exposure (P=0.008). Proportional hazard modeling identified uveitic and neovascular glaucoma as significant confounders of the univariate model (P=0.024), although the main effect of BAK exposure was maintained with a hazard ratio of 1.21 (P=0.032). The number of different medications used to control intraocular pressure did not significantly affect survival time in a secondary Cox model (P=0.948). Conclusions:Increased preoperative exposure to ophthalmic solutions preserved with BAK is a risk factor for earlier surgical failure, independent of the number of medications used. This study extends earlier findings of potential adverse effects of ophthalmic preservatives on surgical outcomes to the modern pharmacopeia used in the medical management of glaucoma.
Journal of Glaucoma | 2011
Yingwei Liu; Catherine M. Birt
ObjectiveTo compare the effectiveness of argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT) in lowering intraocular pressure (IOP) in younger patients (age 60 or less). MethodsThis was a prospective randomized control trial. Forty-two young patients (age 29 to 60 y) had 1 eye randomized to ALT (n=22) or SLT (n=20). IOP was measured before laser and 1 hour, 1 day, 6 weeks, 3 months, every 3 months until 2 years, and then yearly postlaser. Chi-square analysis and Student t test were used to determine statistical significance. ResultsThe mean IOP before treatment was 21.9 mm Hg for ALT and 19.1 mm Hg for SLT with no statistical difference between the groups (P>0.05). At 2 years, 86.4% of ALT and 75.0% of SLT eyes required no further surgical intervention (laser trabeculoplasty or trabeculectomy). During the same time period, there was a statistically significant IOP decrease of 11.1% after ALT (P=0.01) and 7.7% after SLT (P=0.01) with no statistical difference between the lasers (P>0.05). ConclusionsIn younger patients, both ALT and SLT have a significant ocular hypotensive effect 2 years after treatment, with no differences in outcome identified between the laser modalities.
Journal of Glaucoma | 2015
Shefalee Shukla Kent; Cindy M. L. Hutnik; Catherine M. Birt; Karim F. Damji; Paul Harasymowycz; Francie Si; Irene Pan; Andrew Crichton
Purpose:To evaluate the efficacy of selective laser trabeculoplasty (SLT) versus argon laser trabeculoplasty (ALT) in lowering the intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension secondary to pseudoexfoliation. Design:Multicentered randomized clinical trial. ParticipantsA total of 76 eyes from 60 patients with pseudoexfoliation and uncontrolled IOP were recruited from 5 Canadian academic institutions. Patients with prior laser trabeculoplasty, ocular surgery within 6 months, previous glaucoma surgery, an advanced visual field defect, current steroid use, and monocular patients were excluded. Methods:Eyes were randomized to receive either 180-degree SLT or 180-degree ALT by a nonblocked randomization schedule stratified by center. Main Outcome Measurement:The primary outcome was the change in IOP at 6 months versus baseline and secondary outcomes included change in number of glaucoma medications after laser. Baseline variables included age, sex, angle grade, angle pigmentation, and number of glaucoma medications. Results:Of the 76 eyes, 45 eyes received SLT and 31 eyes received ALT. The overall age was 72.9 years (65% females). The baseline IOPs in the SLT and ALT groups were 23.1 and 25.2 mm Hg, respectively (P=0.03). The IOP reduction 6 months after SLT was −6.8 mm Hg and post-ALT was −7.7 mm Hg (P>0.05). The SLT group had reduced glaucoma medications by 0.16 medications at 6 months and the ALT group had no decrease in medications over the same time period (P=0.59). There were no postlaser IOP spikes in either group. Discussion:ALT and SLT are equivalent in lowering IOP at 6 months posttreatment in patients with PXF.
Canadian Journal of Ophthalmology-journal Canadien D Ophtalmologie | 2005
Asif Salyani; Catherine M. Birt
BACKGROUND Methods to improve patient compliance with prescribed topical use of glaucoma medication are sorely needed. A guide for the topical administration of ocular medication was suggested as such a tool. We investigated whether eye drop self-administration would be improved with use of the guide. METHODS An eye drop guide, a funnel-shaped device designed to fit within the contour of the orbital margins, was offered to 114 patients for use at home with their glaucoma medication. A questionnaire asking about the ease of eye drop self-administration was administered before and after 1 weeks use of the device. RESULTS Of the 111 patients who accepted the guide, 93 returned a usable completed questionnaire. Seventy-four percent said that they found it easier to administer their eye drops without the guide and preferred to do so (chi2 = 21.77, p < 0.01). Patients using more doses per day found it more difficult to administer their drops using the guide (r = -0.233, p < 0.05), and those who had been using drops longer preferred not to continue using the guide (r = -0.222, p < 0.05). Patients who found the written instructions clearer found it easier to administer their drops using the guide (r = 0.329, p < 0.05). INTERPRETATION Although intended to ease the administration of eye drops, the guide proved to be counterproductive. Further work is necessary to investigate other methods of improving patient compliance with prescribed topical use of ocular medications.
Canadian Journal of Ophthalmology-journal Canadien D Ophtalmologie | 2011
Vasilios Tzimis; Lai Tze; Jeetangie Ganesh; Sana Muhsen; Alex Kiss; Christoph Kranemann; Catherine M. Birt
OBJECTIVE To examine the effectiveness of argon (ALT) or selective (SLT) laser trabeculoplasty (LTP) in lowering intraocular pressure (IOP) and to determine whether patient-related factors had any impact on outcome. DESIGN Retrospective review. PARTICIPANTS 500 patients treated with LTP over 14 years. METHODS This study was conducted at Sunnybrook Health Sciences Centre, University of Toronto. Five patient-related characteristics were used as dependent variables-age, race, gender, pseudophakic status, and pseudoexfoliation. IOP decrease and treatment failure at 12 months were the main outcome variables. RESULTS 500 eyes of 500 patients were included, 350 after ALT and 150 after SLT. The mean ± standard deviation baseline IOP was significantly higher in the patients treated by ALT than in those treated by SLT (24.2 ± 5.4 versus 22.2 ± 4.6, p < 0.0001) at baseline but not at 1 year (19.6 ± 5.1 versus 19.5 ± 6.1, p = 0.41). When the final IOP was examined by multiple regression analysis, there was a significant effect in favor of ALT over SLT (p = 0.03) and for patients with higher baseline IOPs (p < 0.0001). No significant effect was found for any of the demographic subgroupings. However, when the outcome variable was success or failure, only the baseline IOP remained significant. CONCLUSIONS Specific patient characteristics do not significantly influence LTP outcome after 12 months of follow-up. The most powerful predictor of either final IOP or clinical success was a higher baseline IOP, but ALT may have a better ability to lower IOP.
Journal of Glaucoma | 2009
Mustafa Kapasi; Catherine M. Birt
PurposeTo determine the efficacy of a subconjunctival needling revision using 5-fluorouracil (5FU) when administered to patients who have nonfiltering, flat, or encapsulated blebs over 1 year after the original surgery. MethodsThe charts of 37 glaucoma patients, who had undergone both a trabeculectomy filtering procedure and a subconjunctival 5FU needling revision, with a minimum interval of 1 year between these procedures and with no intervening surgical procedures, were retrospectively reviewed. The needling was a clinic procedure using a 30-gauge needle and 0.1 mL of 50 mg/mL 5FU. ResultsIntraocular pressure (IOP) decreased by an average of 10.5 mm Hg (44.8%) immediately after the needling procedure. Eleven eyes (29.7%) achieved absolute success, defined as IOP control with no further needling revision, surgical intervention, or antiglaucoma medication in the 2-year follow-up period. Thirteen eyes (35.1%) achieved a qualified success, defined as IOP control with resumed medication use, undergoing a laser procedure, or a repeat needling within the follow-up period. Thirteen eyes (35.1%) failed the procedure by requiring a repeat surgical intervention. The mean IOP was 16.3±4.6 mm Hg in the success group, 15.5±6.5 mm Hg in the qualified success group, and 27.7±8.9 mm Hg in the failure group at the end of follow-up. ConclusionsLate 5FU needling is an effective method to control IOP and avoid further surgery in a high proportion of patients with medically uncontrolled nonfiltering blebs.
Journal of Ophthalmology | 2012
Yvonne M. Buys; Paul Harasymowycz; Rania Gaspo; Kenneth Kwok; Cindy M. L. Hutnik; Pierre Blondeau; Catherine M. Birt; Robert L. G. Piemontesi; Lisa F. Gould; Mark R. Lesk; Iqbal K. Ahmed
Purpose. To describe the distribution of ocular variables, risk factors, and disease severity in newly diagnosed ocular hypertension (OH) or open-angle glaucoma (OAG). Methods. Eligible subjects underwent a complete history and examination. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) obtained from multiple logistic regression models were used to compare OAG to OH and advanced to early/moderate OAG. Results. 405 subjects were enrolled: 292 (72.1%) with OAG and 113 (27.9%) with OH. 51.7% had early, 27.1% moderate, and 20.9% advanced OAG. The OR for OAG versus OH was 8.19 (P < 0.0001) for disc notch, 5.36 (P < 0.0001) for abnormal visual field, 1.45 (P = 0.001) for worsening mean deviation, 1.91 (P < 0.0001) for increased cupping, 1.03 for increased age (P = 0.030), and 0.36 (P = 0.010) for smoking. Conclusions. Increased age was a risk for OAG, and smoking decreased the risk of OAG compared to OH. Almost half of the OAG subjects had moderate/advanced disease at diagnosis.
Journal of Glaucoma | 2010
Catherine M. Birt; Yvonne M. Buys; Iqbal Ike K. Ahmed; Graham E. Trope
PurposeLatanoprost, travoprost, and bimatoprost are prostaglandin or prostamide-type ocular hypotensive medications, all of which are effective and safe for lowering intraocular pressure (IOP). Most studies with these types of drugs have included patients mainly from European or white ethnic backgrounds; however, some reports have suggested that there is a difference in response between patients of white and African racial heritage. On account of the possibility that drugs may act differently in people of different ethnic background, we decided to study the effectiveness and safety of all 3 drugs in people from various ethnic heritages. Our hypothesis was that there might be a possible ethnic-based difference in IOP-lowering effectiveness between the 3 medications. MethodThis was a prospective randomized investigator-masked multicenter study. Patients newly diagnosed with open-angle glaucoma (primary, pseudoexfoliative, or pigmentary), or whose pressure became elevated after a washout period, were randomized to receive 1 of 3 prostaglandin/prostamide drugs. Assignment of drug was balanced by racial group and study site, and the investigator was masked to the drug used. The patients were requested to self-identify their racial group as White, African, East Indian, Asian, or Hispanic; to minimize the possibility of heterogeneity, all 4 grandparents had to be known to originate from the same group. However, for purposes of analysis, the patients were divided into 2 groups—White or Other. Patients were followed at 2, 6, 12, and 24 weeks; IOP and local side effects were assessed at each visit. ResultsEighty-three patients were recruited from 9 sites. The mean age of the patients was 61.5±10.5 years. There were no differences in mean age or the distribution of sex between the patients whether examined by the 2 racial groups or the 3 drug groups. There was a highly statistically significant decrease in IOP from baseline to 12 weeks and from baseline to 24 weeks (F=439.3, P<0.0001; F=305.94, P<0.0001). There were no differences in treatment effect between the 3 drugs or between the 2 ethnic groups, (P>0.05 for all comparisons) and there was no interaction between race and drug. ConclusionsAll 3 prostaglandin/amide drugs are highly effective at lowering IOP. No differences in effect between the drugs or between members of different racial groups were detected, although the study sample size was too small to be certain to detect differences, if they existed.
Canadian Journal of Ophthalmology-journal Canadien D Ophtalmologie | 2004
Catherine M. Birt
BACKGROUND The role of laser peripheral iridotomy to break a suspected reverse pupil block in the long-term control of pigment dispersion is promising, but the usefulness of this procedure has not been completely established. The author examined whether patients with pigment dispersion are at higher risk for an intraocular pressure (IOP) spike after laser peripheral iridotomy due to possible compromise of trabecular meshwork function, compared with patients undergoing prophylactic peripheral iridotomy for an occludable angle. METHODS Data were collected prospectively on the first eye of 87 patients with occludable angles and 13 patients with pigment dispersion treated with peripheral laser iridotomy between November 1995 and October 1996 at the glaucoma service of a university-affiliated hospital in Toronto. All patients received one drop of 0.5% apraclonidine before the procedure. IOP was measured before and 1 and 24 hours after the procedure. RESULTS There was no difference between the two groups in the distribution of right vs. left eyes, sex, race, the mean total energy required to produce a patent iridotomy, the mean number of medications used or the mean IOP before the procedure. The patients with pigment dispersion were significantly younger than those with occludable angles (mean age [and standard deviation (SD)] 40.5 [9.45] years vs. 66.4 [10.78] years) (p < 0.001). There was no difference between the two groups in mean IOP at 1 hour or at 24 hours. Twenty-nine patients (33%) in the occludable angle group and seven (54%) in the pigment dispersion group had an IOP spike greater than 2 mm Hg after the procedure (p = 0.001). Among these patients, the mean IOP (36.4 [SD 10.83] mm Hg vs. 30.3 [SD 7.04] mm Hg, p = 0.05) and the mean rise in IOP (14.0 [SD 10.63] mm Hg vs. 8.7 [SD 4.73] mm Hg, p = 0.04) were significantly higher in those with pigment dispersion than in those with occludable angles. Among the patients who used antiglaucoma medications before the procedure or had a prelaser IOP level greater than 22 mm Hg, those with pigment dispersion were more likely than those with occludable angles to have an IOP spike at 1 hour (p < or = 0.005). INTERPRETATION Patients with pigment dispersion undergoing iridotomy to break a reverse pupil block should be carefully assessed after the procedure, as significant pressure spikes requiring treatment may occur.
Canadian Journal of Ophthalmology-journal Canadien D Ophtalmologie | 2012
Kathy Y. Cao; Mustafa Kapasi; Janet A. Betchkal; Catherine M. Birt
OBJECTIVE To determine whether a relationship exists between central corneal thickness (CCT) and visual field (VF) progression in treated patients with open-angle glaucoma and asymmetric corneal thickness. DESIGN Retrospective chart review. PARTICIPANTS We studied 100 charts of patients with open-angle glaucoma and also bilateral CCT and VF data. METHODS Charts from 2 glaucoma subspecialty practices were reviewed. The CCT and the rate of progression and event analysis of visual field data were assessed in all subjects. Subanalysis was performed for subjects whose CCT asymmetry was ≥ 16 μm. RESULTS The mean CCT was 544 ± 40 μm OD and 541 ± 40 μm OS. The mean CCT difference between fellow eyes was 15 ± 11 μm (range, 1 to 52 μm). There was no significant intrasubject difference in the mean deviation (MD) and the pattern standard deviation (PSD) (p =0.917 and p = 0.704, respectively; paired t test). The more advanced VF MDs and PSDs were found in the thin eyes of 47 and 50 subjects, respectively (p = 0.459 and p = 0.317, respectively; χ(2)). Of the 65 subjects whose visual field indexes were available, 34 had the more rapid visual field index rates of progression in the thin eye (p = 0.400; χ(2)). Of the 27 subjects for whom event analysis was available, 15 had the worse progression category in the thin eye (p = 0.453, χ2). Subgroup analysis of 48 subjects with ≥ 16 μm CCT asymmetry did not find any significant difference in analyses of field progression between fellow eyes. CONCLUSIONS No relationship was found between CCT and VF loss in treated patients with primary open-angle glaucoma or normal-tension glaucoma with asymmetrical CCT. Specifically, the thin eye did not have the more advanced VF loss or more rapid VF progression.