Michael A Coote

University of Melbourne, Melbourne, Victoria, Australia

Are you Michael A Coote?

Claim your profile

Publications (36)187.24 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Control of intraocular pressure after implantation of a glaucoma drainage device (GDD) depends on the porosity of the capsule that forms around the plate of the GDD. To compare capsular porosity after insertion of 2 different GDDs using a novel implant and measurement system. We performed an experimental interventional study at an eye research facility in a tertiary eye care center. Testing was performed on 22 adult New Zealand white rabbits that received the experimental GDD or an existing GDD. A new experimental GDD, the Center for Eye Research Australia (CERA) implant, was created using computer-aided design and a 3-dimensional printer. The CERA GDDs were implanted in the eyes of rabbits randomized into 1 of the following 3 groups: with no connection to the anterior chamber (n = 7), with connection to the anterior chamber for 1 week (n = 5), and with connection to the anterior chamber for 4 weeks (n = 5). In a control group (n = 5), a pediatric GDD was implanted without connection to the anterior chamber. We measured the capsular porosity using a pressure-gated picoliter pump at a driving pressure of 12 mm Hg. The animals were killed humanely for histologic study. Porosity of the fibrous capsule around the implant. We found no difference in mean (SEM) capsular porosity between the CERA (3.39 [0.76; 95% CI, 1.43-5.48] µL/min) and pediatric (4.52 [0.52; 95% CI, 3.19-5.95] µL/min) GDDs (P = .28, unpaired t test) at 4 weeks without aqueous exposure. Mean (SEM) capsular porosity of CERA GDDs connected to the anterior chamber at 1 week was 2.46 (0.36; 95% CI, 1.55-3.44) µL/min but decreased to 0.67 (0.07; 95% CI, 0.49-0.86) µL/min at 4 weeks (P = .001, unpaired t test). Our experimental method permits direct measurement of capsular porosity of an in situ GDD. In a comparison between an experimental (CERA) and an existing GDD, no differences were identified in capsular porosity or histologic reaction between the implants. These results suggest that the CERA GDD model can be used to test key components of glaucoma surgery and implant design.
    No preview · Article · Feb 2015 · Jama Ophthalmology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Exfoliation syndrome (XFS) is the most common recognizable cause of open-angle glaucoma worldwide. To better understand the etiology of XFS, we conducted a genome-wide association study (GWAS) of 1,484 cases and 1,188 controls from Japan and followed up the most significant findings in a further 6,901 cases and 20,727 controls from 17 countries across 6 continents. We discovered a genome-wide significant association between a new locus (CACNA1A rs4926244) and increased susceptibility to XFS (odds ratio (OR) = 1.16, P = 3.36 × 10(-11)). Although we also confirmed overwhelming association at the LOXL1 locus, the key SNP marker (LOXL1 rs4886776) demonstrated allelic reversal depending on the ancestry group (Japanese: ORA allele = 9.87, P = 2.13 × 10(-217); non-Japanese: ORA allele = 0.49, P = 2.35 × 10(-31)). Our findings represent the first genetic locus outside of LOXL1 surpassing genome-wide significance for XFS and provide insight into the biology and pathogenesis of the disease.
    Full-text · Article · Feb 2015 · Nature Genetics

  • No preview · Article · Nov 2014 · Clinical and Experimental Ophthalmology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Importance Glaucoma is a significant health problem for which diagnosis remains suboptimal. Optic disc evaluation, which is fundamental to the diagnosis, is a difficult skill to acquire.Objectives To determine the optic disc characteristics that most influence decision making in the assessment of glaucoma likelihood and to ascertain the optic disc features associated with overestimation and underestimation of glaucoma likelihood.Design, Setting, and Participants This prospective, observational, Internet-based study with multinational participation included 197 ophthalmic clinicians (37 glaucoma subspecialists, 51 comprehensive ophthalmologists, and 109 ophthalmology trainees) from 22 countries who self-registered for the Glaucomatous Optic Neuropathy Evaluation (GONE) Project from December 1, 2008 through June 30, 2010.Interventions A series of 42 monoscopic optic disc photographs of healthy and glaucomatous eyes were presented to clinicians using the GONE Project Program. Participants were asked to assess each disc according to 9 conventional topographic features and assign a presumptive grade for glaucoma likelihood.Main Outcomes and Measures Agreement (κ and weighted κ) among participants for disc signs and glaucoma likelihood and contributions of disc-related factors to overestimation and underestimation of glaucoma likelihood.Results Ophthalmology trainees and comprehensive ophthalmologists underestimated glaucoma likelihood in a mean (SD) of 22.1% (1.6%) and 23.8% (1.8%) of discs, respectively. Underestimation of vertical cup-disc ratio and failure to identify retinal nerve fiber layer loss, disc hemorrhage, or rim loss were most likely to lead to underestimation of glaucoma. When all 4 features were inaccurately assessed, underestimation of glaucoma likelihood increased to 43.0%. Ophthalmology trainees and comprehensive ophthalmologists overestimated glaucoma likelihood in a mean (SD) of 13.0% (1.2%) and 8.9% (1.3%) of discs, respectively. Overestimation of glaucoma likelihood was associated with overestimation of retinal nerve fiber layer loss, rim loss, vertical cup-disc ratio, disc hemorrhage, and incorrect assessment of disc tilt and was more likely in large discs.Conclusions and Relevance Ophthalmology trainees and comprehensive ophthalmologists underestimated glaucoma likelihood in approximately 1 in 5 disc photographs and were twice as likely to underestimate as overestimate glaucoma likelihood. Underestimating the vertical cup-disc ratio and cup shape and missing retinal nerve fiber layer defects and disc hemorrhage were the key errors that led to underestimation. When all 4 parameters were incorrectly assessed, underestimation increased to almost 1 in 2.
    Full-text · Article · Apr 2014 · Jama Ophthalmology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To determine whether monoscopic versus stereoscopic viewing impacts on evaluation of optic disc photographs for glaucoma diagnosis in an expert population. Prospective observational study. Twenty pairs of high-quality monoscopic and stereoscopic photographs of similar size and magnification (i.e. forty images), were selected to demonstrate a range of optic disc features from a total of 197 eyes of 197 patients with glaucoma and normal subjects recruited from a tertiary clinic. These were presented in randomised order via an interactive platform (http://stereo.gone-project.com/). Participants assessed nine topographic features and estimated glaucoma likelihood for each photograph. Main outcome measures were intra- and inter-observer agreement. There was good intra-observer agreement between monoscopic and stereoscopic assessments of glaucoma likelihood (κw=0.56). There was also good to substantial agreement for peripapillary atrophy (κw=0.65), cup shape (κw=0.65), retinal nerve fibre layer loss (κw=0.69), vertical cup:disc ratio (κw=0.58) and disc shape (κw=0.57). However, intra-observer agreement was only fair to moderate for disc tilt, cup depth and disc size (κw=0.46-0.49). Inter-observer agreement for glaucoma likelihood in monoscopic photographs (κw=0.61, CI=0.55-0.67) was substantial and not lower than stereoscopic photographs (κw=0.59, CI=0.54-0.65). Monoscopic photographs did not lead to lower levels of inter-observer agreement compared to stereoscopic photographs in the assessment of any optic disc characteristics, for example disc size (mono κw=0.65, stereo κw=0.52); and CDR (mono κw=0.72, stereo κw=0.62). For expert observers in the evaluation of optic disc photographs for glaucoma likelihood, monoscopic optic disc photographs did not appear to represent a significant disadvantage compared to stereoscopic photographs.
    Full-text · Article · Feb 2014 · American Journal of Ophthalmology
  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the effect of phacoemulsification on trabeculectomy function. Retrospective case-control study. Forty-eight patients who underwent trabeculectomy surgery and had at least 2 years of follow up. Patients were classified into two groups: patients who had phacoemulsification subsequent to trabeculectomy (Trab_phaco, n = 18) and patients who were pseudophakic for greater than 6 months preceding their trabeculectomy (Phaco_trab, n = 30). Groups were matched for length of follow up of 2 years from time of trabeculectomy. The primary outcome measures were target intraocular pressure of criteria A, ≤12 mmHg; B, ≤15 mmHg; C, ≤18 mmHg with or without additional topical treatment. A separate measure for bleb function failure was also used; with failure defined as the need for additional topical antiglaucoma therapy or surgical intervention to achieve control of intraocular pressure. There was no significant difference in achieving each intraocular pressure criterion between groups (12 months, P = 1.0; 24 months, P = 0.330). In the first 12 months, significantly more trabeculectomies in the Trab_phaco group failed, requiring additional intervention to control the IOP (39%) compared with the Phaco_trab (10%) group (P = 0.028). Although this trend continued at 24 months, there were no significant differences in failure rates (P = 0.522). Phacoemulsification performed after trabeculectomy significantly increased rates of bleb failure in the following 12 months but not at 24 months.
    No preview · Article · Oct 2013 · Clinical and Experimental Ophthalmology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: The aim of our study was to determine whether IOP lowering in glaucomatous and ocular hypertensive (OHT) eyes leads to an improvement in the full-field photopic negative response (PhNR) of the electroretinogram. Methods: A prospective nonrandomized interventional cohort study was conducted. Patients with OHT or glaucomatous optic neuropathy were recruited, and photopic full-field electroretinograms (ERG) were performed at baseline and then repeated 1 to 2 months later. The change in PhNR amplitude was compared between those eyes that had a significant lowering in IOP (defined as >25% decrease from baseline or to a predetermined target IOP) during follow-up and those that did not. Results: From a cohort of 30 eyes, 18 eyes had a significant reduction in IOP during follow-up (n = 18) and 12 eyes had no significant change in IOP (<25% reduction in IOP, n = 12). A significant increase in PhNR amplitude and the PhNR/b-wave amplitude ratios was observed in the reduced IOP group, but not in the IOP stable group for the two flash intensities used (2.25 and 3.00 cd.s/m(2)). Conclusions: The full-field PhNR amplitude provides a potentially reversible measure of inner retinal function that improves after IOP lowering. Further study now is required to assess its use as a measure of optic nerve health in glaucoma patients.
    No preview · Article · Feb 2013 · Investigative ophthalmology & visual science

  • No preview · Article · Dec 2012 · Clinical and Experimental Ophthalmology
  • Tu Tran · Surinder Pandav · Michael Coote · Jonathon Crowston

    No preview · Article · Dec 2012 · Clinical and Experimental Ophthalmology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: Prior models of glaucoma filtration surgery assess bleb morphology, which does not always reflect function. Our aim is to establish a model that directly measures tissue hydraulic conductivity of postsurgical outflow in rabbit bleb capsules following experimental glaucoma filtration surgery. Methods: Nine rabbits underwent insertion of a single-plate pediatric Molteno implant into the anterior chamber of their left eye. Right eyes were used as controls. The rabbits were then allocated to one of two groups. Group one had outflow measurements performed at 1 week after surgery (n = 5), and group two had measurements performed at 4 weeks (n = 4). Measurements were performed by cannulating the drainage tube ostium in situ with a needle attached to a pressure transducer and a fluid column at 15 mm Hg. The drop in the fluid column was measured every minute for 5 minutes. For the control eyes (n = 6), the anterior chamber of the unoperated fellow eye was cannulated. Animals were euthanized with the implant and its surrounding capsule dissected and fixed in 4% paraformaldehyde, and embedded in paraffin before 6-μm sections were cut for histologic staining. Results: By 7 days after surgery, tube outflow was 0.117 ± 0.036 μL/min/mm Hg at 15 mm Hg (mean ± SEM), whereas at 28 days, it was 0.009 ± 0.003 μL/min/mm Hg. Control eyes had an outflow of 0.136 ± 0.007 μL/min/mm Hg (P = 0.004, one-way ANOVA). Hematoxylin and eosin staining demonstrated a thinner and looser arrangement of collagenous tissue in the capsules at 1 week compared with that at 4 weeks, which had thicker and more densely arranged collagen. Conclusions: We describe a new model to directly measure hydraulic conductivity in a rabbit glaucoma surgery implant model. The principal physiologic endpoint of glaucoma surgery can be reliably quantified and consistently measured with this model. At 28 days post glaucoma filtration surgery, a rabbit bleb capsule has significantly reduced tissue hydraulic conductivity, in line with loss of implant outflow facility, and increased thickness and density of fibrous encapsulation.
    No preview · Article · Sep 2012 · Investigative ophthalmology & visual science
  • Source
    Michael Coote · Jonathan Crowston
    [Show abstract] [Hide abstract]
    ABSTRACT: Revision trabeculectomy is used to describe any surgical intervention subsequent to an existing trabeculectomy. Mostly, it is used to describe resurgery for failure of trabeculectomy, as defined by inadequate pressure control. Revision may also be performed for unsafe, uncomfortable or leaking blebs. Mostly bleb failure occurs within the subconjunctival space, although the flap and ostium may be involved or causative. Clear surgical principles, meticulous surgical technique and scrupulous postoperative care are key to successful revision surgery. This review is an attempt to elucidate the technique of bleb revision for bleb failure.
    Preview · Article · Sep 2012

  • No preview · Article · Aug 2012 · Clinical and Experimental Ophthalmology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: To determine whether postoperative subconjunctival bevacizumab significantly alters bleb vascularity. Design: A randomized, prospective interventional study. Participants: Forty-three eyes from 39 patients were recruited, with 21 eyes randomized to subconjunctival injections of 5-fluorouracil, and 22 eyes to combined 5-fluorouracil/bevacizumab. Methods: All patients who underwent uncomplicated primary antimetabolite augmented trabeculectomy who subsequently required postoperative subconjunctival 5-fluorouracil injection within 4 weeks of surgery were eligible. Patients were randomized to receive subconjunctival 5-fluorouracil only (7.5 mg/0.15 mL) or 5-fluorouracil plus bevacizumab (1.25 mg/0.05 mL). Main Outcome Measures: Primary outcome was bleb vascularity with secondary endpoints including visual acuity, intraocular pressure, bleb morphology, complications and total numbers of 5-fluorouracil injections were recorded at baseline, week 12 and 18 months. Results: At week 12, there was no significant difference between groups for visual acuity, intraocular pressure, bleb vascularity and morphology, or total number of 5-fluorouracil injections. By 18 months, 47.4% of the 5-fluorouracil/bevacizumab group exhibited central bleb avascularity compared with 21.1% of the 5-fluorouracil group (Fisher's exact test, P = 0.17). Two bleb complications (one blebitis; one suture abscess) recorded in the 5-fluorouracil/bevacizumab group. Conclusions: After a single combined injection, a trend for increased central bleb avascularity was observed, although this effect was not sufficient to reach statistical significance. This, in addition to the occurrence of two bleb-related complications in the bevacizumab group, suggests the need for a larger clinical trial to further evaluate the safety and efficacy of bevacizumab as a modulating agent in glaucoma filtration surgery.
    Preview · Article · Mar 2012 · Clinical and Experimental Ophthalmology
  • [Show abstract] [Hide abstract]
    ABSTRACT: To demonstrate that the intraocular pressure (IOP)-lowering effect of travoprost 0.004% preserved with polyquaternium-1 (travoprost benzalkonium chloride [BAK]-free) is non-inferior to that of travoprost 0.004% preserved with benzalkonium chloride (travoprost BAK) in patients with ocular hypertension or open-angle glaucoma. A total of 371 patients randomly received travoprost BAK-free (n=185) or travoprost BAK (n=186) dosed once daily in the evening for 3 months. Patients were evaluated at 9 am, 11 AM, and 4 PM at baseline, weeks 2 and 6, and month 3. Intraocular pressure was also evaluated 36 and 60 hours after the month 3 visit. Travoprost BAK-free is non-inferior to travoprost BAK. The 95% upper confidence limits for the difference in mean IOP at month 3 (primary efficacy) were 0.5 mmHg, 0.6 mmHg, and 0.5 mmHg, at 9 AM, 11 AM, and 4 PM, respectively. Mean IOP reductions from baseline ranged from 7.6 to 8.7 mmHg in the travoprost BAK-free group and from 7.7 to 9.2 mmHg in the travoprost BAK group. At 36 and 60 hours after the last dose, mean IOP remained 6.8 mmHg and 5.7 mmHg below baseline in the travoprost BAK-free group, vs 7.3 mmHg and 6.0 mmHg in the travoprost BAK group, respectively. The safety profile of travoprost BAK-free was similar to that of travoprost BAK. Travoprost BAK-free safely and effectively lowers IOP in eyes with open-angle glaucoma or ocular hypertension. This BAK-free formulation has comparable safety, efficacy, and duration of IOP-lowering effect to travoprost preserved with BAK. Travoprost BAK-free is an effective option for IOP reduction while avoiding BAK exposure.
    No preview · Article · Jan 2012 · European journal of ophthalmology
  • [Show abstract] [Hide abstract]
    ABSTRACT:   Glaucoma is a sight-threatening disease affecting 3% of the population over the age of 50. Glaucoma is treatable, and severe vision loss can usually be prevented if diagnosis is made at an early stage. Genetic factors play a major role in the pathogenesis of the condition, and therefore, genetic testing to identify asymptomatic at-risk individuals is a promising strategy to reduce the prevalence of glaucoma blindness. Furthermore, unravelling genetic risk factors for glaucoma would also allow a better understanding of the pathogenesis of the condition and the development of new treatments.   The Australian and New Zealand Registry of Advanced Glaucoma is a prospective study that aims to develop a large cohort of glaucoma cases with severe visual field loss to identify novel genetic risk factors for glaucoma blindness.   Clinical information and blood are collected from participants after referral by eye practitioners. Samples are collected across Australia and New Zealand using postage kits.   Our registry has recruited just over 2000 participants with advanced glaucoma, as well as secondary and developmental glaucomas.   A positive family history of glaucoma is present in more than half of the advanced glaucoma cases and the age at diagnosis is significantly younger for participants with affected relatives, which reinforces the involvement of genetic factors in glaucoma.   With the collection of glaucoma cases recruited so far, our registry aims to identify novel glaucoma genetic risk factors to establish risk profiling of the population and protocols for genetic testing.
    No preview · Article · Dec 2011 · Clinical and Experimental Ophthalmology
  • [Show abstract] [Hide abstract]
    ABSTRACT: To report the long-term efficacy and safety of same site revision trabeculectomy with mitomycin application via a posterior approach. A noncomparative retrospective case series of consecutive revision trabeculectomies performed for inadequate bleb function between March 2003 and March 2007 by a single surgeon. Surgery involved a posterior/fornix incision with opening of the scleral flap posteriorly at the same site as previous surgery and application of 0.2 to 0.4 mg/mL mitomycin. Fifty-seven eyes were followed for an average of 33 ± 15 months. Mean baseline intraocular pressure (IOP) reduced from 21.5 ± 6.5 to 11.2 ± 4.4 and 8 ± 3.6 mm Hg at 1 and 5 years, respectively (P<0.001). On Kaplan-Meier survival analysis the probability of maintaining IOP ≤ 15 mm Hg without medication at the end of 1 year was 95% (n=57) and at 3 (n=36) and 5 years (n=7) was 84%. Eighty-five percent of patients were on no antiglaucoma drops at last follow-up. Four cases required a second procedure (7%), transient choroidal effusions occurred in 4 eyes (7%), corneal decompensation in 1 eye (1.7%), and ptosis in 1 (1.7%). Posterior approach to surgical revision of failed filtration surgery is an effective procedure with good long-term control of IOP.
    No preview · Article · Aug 2011 · Journal of glaucoma

  • No preview · Article · Jun 2011 · Clinical and Experimental Ophthalmology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The authors compared the visual gaze behaviors of glaucoma subspecialists with those of ophthalmology trainees during optic disc and retinal nerve fiber layer (RNFL) examination. Seven glaucoma subspecialists and 23 ophthalmology trainees participated in the project. Participants were shown eight glaucomatous optic disc images with varied morphology. Eye movements during examination of the optic disc photographs were tracked. For each disc image, graders were asked to assign a presumptive diagnosis for probability of glaucoma. There was no time restriction. Overall, trainees spent more time looking at disc images than glaucoma subspecialists (21.3 [13.9-37.7] vs. 16.6 [12.7-19.7]) seconds; median [interquartile range (IQR)], respectively; P < 0.01) and had no systematic patterns of gaze behavior, and gaze behavior was unaltered by disc morphology or topographic cues of pathology. Experienced viewers demonstrated more systematic and ordered gaze behavior patterns and spent longer times observing areas with the greatest likelihood of pathology (superior and inferior poles of the optic nerve head and adjacent RNFL) compared with the trainees. For discs with focal pathology, the proportion of total time spent examining definite areas of pathology was 28.9% (22.4%-33.6%) for glaucoma subspecialists and 13.5% (12.2%-19.2%) for trainees (median [IQR]; P < 0.05). Furthermore, experts adapted their viewing habits according to disc morphology. Glaucoma subspecialists adopt systematic gaze behavior when examining the optic nerve and RNFL, whereas trainees do not. It remains to be elucidated whether incorporating systematic viewing behavior of the optic disc and RNFL into teaching programs for trainees may expedite their acquisition of accurate and efficient glaucoma diagnosis skills.
    Full-text · Article · Apr 2011 · Investigative ophthalmology & visual science

  • No preview · Article · Jan 2011 · Clinical and Experimental Ophthalmology
  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the effect of the anti-VEGF-A monoclonal antibody bevacizumab on primary human Tenon's capsule fibroblasts (HTFs) in an in vitro model of wound healing. Fibroblasts were cultured in RPMI media, and bevacizumab was administered at a concentration ranging from 0.25 to 12.5 mg/mL. Fibroblast viability and cell death were assessed using the MTT colorimetric assay, lactate dehydrogenase assay, BrdU assay, and live/dead assay. Fibroblast contractility was assessed in floating collagen gels. Morphologic changes were assessed by transmission electron microscopy. Antifibrosis activities were compared with 5-fluorouracil. Bevacizumab induced a significant dose-related reduction of HTF cell number at 12.5 mg/mL at 72 hours (P < 0.05). Under serum-free conditions, bevacizumab induced significant fibroblast cell death at concentrations greater than 7.5 mg/mL (P < 0.05). Bevacizumab caused a moderate inhibition of fibroblast gel contraction from baseline (P < 0.05). Scanning electron microscopy revealed marked vacuolization in bevacizumab-treated fibroblasts. Bevacizumab disrupted fibroblast proliferation, inhibited collagen gel contraction ability, and induced fibroblast cell death at concentrations greater than 7.5 mg/mL in serum-free conditions. These results demonstrated that bevacizumab inhibited a number of fibrosis activities in culture. These activities may underpin the antifibrosis effect proposed in vivo.
    No preview · Article · Dec 2010 · Investigative ophthalmology & visual science

Publication Stats

803 Citations
187.24 Total Impact Points


  • 2003-2015
    • University of Melbourne
      • • Department of Ophthalmology
      • • Centre for Eye Research Australia
      Melbourne, Victoria, Australia
  • 2000-2014
    • Royal Victorian Eye and Ear Hospital
      Melbourne, Victoria, Australia
  • 1997-2009
    • University of Tasmania
      • • Menzies Research Institute
      • • School of Medicine
      Hobart Town, Tasmania, Australia