Michael A Coote

Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia

Are you Michael A Coote?

Claim your profile

Publications (29)137.29 Total impact

  • 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.
    Jama Ophthalmology 04/2014; · 3.83 Impact Factor
  • [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.
    American Journal of Ophthalmology 02/2014; · 4.02 Impact Factor
  • [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.
    Clinical and Experimental Ophthalmology 10/2013; · 1.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE: The aim of this study was to determine whether intraocular pressure (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 non-randomised 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 pre-determined target IOP) during follow up with those that did not. RESULTS: From a cohort of 30 eyes, eighteen 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 were 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/m2). CONCLUSIONS: The full-field PhNR amplitude provides a potentially reversible measure of inner retinal function that improves after IOP lowering. Further study is now required to assess its utility as a measure of optic nerve health in glaucoma patients.
    Investigative ophthalmology & visual science 02/2013; · 3.43 Impact Factor
  • [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.
    Investigative ophthalmology & visual science 09/2012; 53(11):6914-9. · 3.43 Impact Factor
  • Clinical and Experimental Ophthalmology 08/2012; 40:469-475. · 1.96 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background:  To determine whether postoperative subconjunctival bevacizumab significantly alters bleb vascularity. Design:  A randomised, prospective interventional study. Participants:  43 eyes from 39 patients were recruited, with 21 eyes randomised to subconjunctival injections of 5-FU, and 22 eyes to combined 5-FU/bevacizumab. Methods:  All patients who underwent uncomplicated primary anti-metabolite augmented trabeculectomy who subsequently required post-operative subconjunctival 5-Fluorouracil (5-FU) injection within 4 weeks of surgery were eligible. Patients were randomised to receive subconjunctival 5-FU only (7.5mg/0.15ml) or 5 FU plus bevacizumab (1.25mg/0.05ml). Main Outcome Measures:  Primary outcome was bleb vascularity with secondary endpoints including visual acuity (VA), intraocular pressure (IOP), bleb morphology, complications and total numbers of 5-FU injections were recorded at baseline, week 12 and 18 months. Results:  At week 12, there was no significant difference between groups for VA, IOP, bleb vascularity and morphology or total number of 5-FU injections. By 18 months, 47.4% of the 5-FU/bevacizumab group exhibited central bleb avascularity compared to 21.1% of the 5 FU group (Fisher exact test, p = 0.17). 2 bleb complications (1 blebitis; 1 suture abscess) recorded in the 5 FU/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 suggest the need for a larger clinical trial to further evaluate the safety and efficacy of bevacizumab as a modulating agent in glaucoma filtration surgery. © 2012 The Authors. Clinical and Experimental Ophthalmology © 2012 Royal Australian and New Zealand College of Ophthalmologists.
    Clinical and Experimental Ophthalmology 03/2012; · 1.96 Impact Factor
  • [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.
    European journal of ophthalmology 01/2012; 22(1):34-44. · 0.91 Impact Factor
  • [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.
    Clinical and Experimental Ophthalmology 12/2011; 40(6):569-75. · 1.96 Impact Factor
  • [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.
    Journal of glaucoma 08/2011; 20(6):377-82. · 1.74 Impact Factor
  • Clinical and Experimental Ophthalmology 06/2011; 40(2):212-3. · 1.96 Impact Factor
  • [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.
    Investigative ophthalmology & visual science 04/2011; 52(7):3976-83. · 3.43 Impact Factor
  • Clinical and Experimental Ophthalmology 01/2011; 39(5):473-8. · 1.96 Impact Factor
  • [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.
    Investigative ophthalmology & visual science 12/2010; 51(12):6524-32. · 3.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Optic nerve morphology is affected by genetic and acquired disease. Glaucoma is the most common optic neuropathy; autosomal-dominant optic atrophy (ADOA) and Leber's hereditary optic neuropathy (LHON) are the most prevalent hereditary optic neuropathies. These 3 entities can exhibit similar topographical changes at the optic nerve head. Both ADOA and LHON have been reported to be misdiagnosed as glaucoma. Our aim was to determine whether glaucoma subspecialists and neuro-ophthalmologists can distinguish these diagnoses on optic disc assessment alone. Observational study. Twenty-three optic nerve experts. We randomized and masked 60 high-resolution stereoscopic optic disc photographs (15 ADOA images, 15 LHON, 15 glaucoma, and 15 normal controls). Experts were asked to assess the discs on 12 conventional topographic features and assign a presumptive diagnosis. Intra- and interanalysis was performed using the index of qualitative variation and absolute deviation. Can glaucoma specialists and neuro-ophthalmologists distinguish among the disease entities by optic nerve head phenotype. The correct diagnosis was identified in 85%, 75%, 27%, and 16% of the normal, glaucoma, ADOA, and LHON disc groups, respectively. The proportion of correct diagnoses within the ADOA and LHON groups was significantly lower than both normal and glaucomatous (P<0.001). Where glaucoma was chosen as the most likely diagnosis, 61% were glaucomatous, 34% were pathologic but nonglaucomatous discs, and 5% were normal. There was greater agreement for individual parameters assessed within the normal disc set when compared with pathologic discs (P<0.05). The only parameter to have a significantly greater agreement within the glaucomatous disc set when compared with ADOA or LHON disc sets was pallor, whereby experts agreed on is absence in the glaucomatous discs but were not in agreement on its presence or its absence in the ADOA and LHON discs (P<0.01). Optic neuropathies can result in similar topographic changes at the optic disc, particularly in late-stage disease, making it difficult to differentiate ADOA and LHON from glaucoma based on disc assessment alone. Other clinical parameters such as acuity, color vision, history of visual loss, and family history are required to make an accurate diagnosis.
    Ophthalmology 11/2010; 118(5):964-70. · 5.56 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Development of a standardized internet-based system to self-assess skills in optic disc examination for glaucoma risk assessment. Prospective internet-based observational study. Total of 197 participants (glaucoma subspecialists, general ophthalmologists and trainees) from 22 countries. Forty-two optic disc images demonstrating a range of features were selected from 2500 monoscopic disc photographs of normal and glaucomatous eyes. Images were presented to clinicians via website (http://www.gone-project.com). Participants were asked to assess nine topographic features and make a subjective assessment of glaucoma likelihood. Inter-observer agreement using kappa (κ) or weighted kappa (κ(w) ). There was substantial level of inter-observer agreement between glaucoma subspecialists for assessment of glaucoma likelihood (κ(w) = 0.63). Inter-observer agreement was high for haemorrhage (κ= 0.83) and substantial for disc size, disc shape, cup:disc ratio, peripapillary atrophy and cup shape (κ(w) = 0.59-0.68). Subspecialists had stronger inter-observer agreement for glaucoma likelihood and for most disc characteristics than did trainees: the greatest difference being the assessment for retinal nerve fibre layer loss. Analysis of individual disc answers from ophthalmology trainees showed that discs leading to lower agreement of glaucoma likelihood tend to produce lower agreement for the assessment of cup:disc ratio, cup shape, cup depth and retinal nerve fibre layer. Discs with features of moderate to deep cup or cup:disc ratio between 0.6 and 0.8 also lead to lower agreement in glaucoma likelihood. This internet-based system is a readily accessible and standardized tool, for clinicians globally, that permits self-assessment and benchmarking of skills in optic disc examination.
    Clinical and Experimental Ophthalmology 11/2010; 39(4):308-17. · 1.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Acquired optic neuropathies are a common cause of blindness in adults, and are associated with characteristic morphological changes at the optic nerve head. Accurate and prompt clinical diagnosis, supplemented with imaging where appropriate, is essential to optimize management of the optic neuropathy and to counsel the patient appropriately on its natural history. History taking, optic disc findings, visual field assessment and imaging of the nerve head and surrounding retinal nerve fiber layer are all paramount to achieving the correct diagnosis. This Review highlights the optic nerve head features that are common to the acquired optic neuropathies, and describes the features that can be used to differentiate these various conditions.
    Nature Reviews Neurology 03/2010; 6(4):221-36. · 15.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Glaucoma surgery is the most effective means for lowering intraocular pressure by providing a new route for fluid to exit the eye. This new pathway is through the sclera of the eye into sub-conjunctival tissue, where a fluid filled bleb typically forms under the conjunctiva. The long-term success of the procedure relies on the capacity of the sub-conjunctival tissue to absorb the excess fluid presented to it, without generating excessive scar tissue during tissue remodeling that will shut-down fluid flow. The role of inflammatory factors that promote scarring are well researched yet little is known regarding the impact of physical forces on the healing response. To help elucidate the interplay of physical factors controlling the distribution and absorption of aqueous humor in sub-conjunctival tissue, and tissue remodeling, we have developed a computational model of fluid production in the eye and removal via the trabecular/uveoscleral pathways and the surgical pathway. This surgical pathway is then linked to a porous media computational model of a fluid bleb positioned within the sub-conjunctival tissue. The computational analysis is centered on typical functioning bleb geometry found in a human eye following glaucoma surgery. A parametric study is conducted of changes in fluid absorption by the sub-conjunctival blood vessels, changes in hydraulic conductivity due to scarring, and changes in bleb size and shape, and eye outflow facility. This study is motivated by the fact that some blebs are known to have 'successful' characteristics that are generally described by clinicians as being low, diffuse and large without the formation of a distinct sub-conjunctival encapsulation. The model predictions are shown to accord with clinical observations in a number of key ways, specifically the variation of intra-ocular pressure with bleb size and shape and the correspondence between sites of predicted maximum interstitial fluid pressure and key features observed in blebs, which gives validity to the model described here. This model should contribute to a more complete explanation of the physical processes behind successful bleb characteristics and provide a new basis for clinically grading blebs.
    PLoS ONE 01/2010; 5(10). · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The ‘GIST’ score was developed to facilitate linkage analysis of adult-onset primary open angle glaucoma (POAG) pedigrees in the Glaucoma Inheritance Study of Tasmania (GIST). Previous genetic linkage studies on juvenile open angle glaucoma pedigrees have relied upon an analysis of definitely affected individuals using the ‘single best diagnosis’ convention. Studies of adult-onset POAG have been complicated by limited numbers of unequivocally affected members identified even in very large pedigrees due to the later onset of the disease. Many members of the pedigree may have equivocal clinical features or are too young to show signs of the disease. The ‘GIST score’ is a numeric value between zero and one where zero is clinical certainty of absence of the disease and one is the definitive diagnosis of POAG. The score is developed by assigning relative weighting to key clinical features which results in a ‘pedigee probability’ of the diagnosis being present or absent in a member of a pedigree. Ranking of borderline and unaffected glaucoma subjects allows the laboratory more flexibility in the use of the members of the pedigree for linkage analysis. The score is not intended to have clinical usefulness in management of glaucoma.
    07/2009; 17(4):199-208.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the effect of topical prostaglandin analogue use on the efficacy of selective laser trabeculoplasty (SLT) intraocular pressure (IOP) lowering in patients with open-angle glaucoma.Patients and This retrospective study included 123 consecutive patients who underwent 180 degrees SLT for the first time. Eyes were grouped into those that received prostaglandin analogues before and after SLT (n=74) and those that did not (n=49). The main outcome measure was IOP lowering after SLT. Success was defined as > or =20% reduction in IOP without further glaucoma intervention. There was no significant difference in IOP lowering at 6 months post-laser between the prostaglandin and non-prostaglandin groups (3.9+/-4.8 vs 4.6+/-3.6 mm Hg, P=0.43). Long-term SLT success rates were also not significantly different between the treatment groups (Kaplan-Meier survival analysis, P=0.68). IOP lowering at 6 months was similar in eyes that received no glaucoma medications, monotherapy with or without a prostaglandin analogue, or combination therapy with or without prostaglandin analogues (P=0.81). Logistic regression analysis showed that various patient characteristics including age, sex, type of glaucoma, previous glaucoma surgery, and other glaucoma risk factors did not predict a successful SLT outcome. However, higher pre-operative IOP was found to predict SLT success (odds ratio=1.12, 95% CI=1.02-1.24, P=0.02). The IOP lowering efficacy of SLT is not influenced by the use of topical prostaglandin analogues.
    Eye (London, England) 01/2009; 23(12):2194-9. · 1.97 Impact Factor

Publication Stats

529 Citations
137.29 Total Impact Points


  • 2000–2014
    • Royal Victorian Eye and Ear Hospital
      Melbourne, Victoria, Australia
  • 1997–2013
    • University of Melbourne
      • • Department of Ophthalmology
      • • Centre for Eye Research Australia
      Melbourne, Victoria, Australia
  • 2010
    • University of Western Australia
      • School of Computer Science and Software Engineering
      Perth, Western Australia, Australia
  • 1997–2009
    • University of Tasmania
      • • Menzies Research Institute
      • • School of Medicine
      Hobart Town, Tasmania, Australia