Mark Lesk

Mark Lesk
Université de Montréal/Maisonneuve-Rosemont Hospital

MSc, MD, FRCSC

About

82
Publications
6,341
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2,244
Citations
Citations since 2017
16 Research Items
905 Citations
2017201820192020202120222023050100150
2017201820192020202120222023050100150
2017201820192020202120222023050100150
2017201820192020202120222023050100150
Introduction
Ocular Biomechanics, Ocular Blood Flow and Glaucoma. Spaceflight Associated Neuroretinal Syndrome Optical Coherence Tomography

Publications

Publications (82)
Article
Full-text available
Objective To develop a non-invasive technique to quantitatively assess the pulsatile deformation due to cardiac contractions of the optic nerve head (ONH). Design Evaluation of a diagnostic test or technology. Participants Healthy subjects with no history of refractive surgery, divided in two cohorts based on their axial length. Methods We prese...
Article
Purpose: Ocular rigidity (OR) is an important biomechanical parameter of the eye accounting for the material and geometrical properties of the corneoscleral shell. Methods: This study used a literature search to review the role of ocular rigidity and the application of potential therapies targeting this parameter in glaucoma and myopia. Conclusion:...
Article
Objective Evidence suggests that ocular blood flow dysregulation in vasospastic patients could occur in response to biomechanical stimuli, contributing to optic nerve head susceptibility in glaucoma. We evaluate the role of vasospasticity in the association between ocular rigidity (OR) and neuroretinal damage, hypothesizing that low OR correlates w...
Chapter
Glaucoma is a multifactorial disease leading to irreversible damage to the retinal ganglion cells’ axons and consequent visual field loss. Despite investigations over the last century to elucidate the link between ocular rigidity (OR) and the pathophysiology of glaucoma, our understanding of this association remains limited. Some evidence suggests...
Article
Full-text available
Purpose: Ocular rigidity (OR) is an important biomechanical property, thought to be relevant in the pathophysiology of open-angle glaucoma (OAG). This study aims to evaluate the relationship between OR and neuroretinal damage caused by glaucoma. Methods: One hundred eight subjects (22 with healthy eyes, 23 with suspect discs, and 63 with OAG) were...
Article
Background/aims To evaluate the non-invasive measurement of ocular rigidity (OR), an important biomechanical property of the eye, as a predictor of intraocular pressure (IOP) elevation after anti-vascular endothelial growth factor (anti-VEGF) intravitreal injection (IVI). Methods Subjects requiring IVI of anti-VEGF for a pre-existing retinal condi...
Article
Background and purpose: Age-related macular degeneration (AMD) is a complex multifactorial neurodegenerative disease treated by anti-VEGF intravitreal injections. As inflammation has a potential pathological role in retinal degeneration, the pro-inflammatory kallikrein-kinin system might be a relevant alternative pharmacological target. The presen...
Article
Ocular rigidity (OR) is thought to play a role in the pathogenesis of glaucoma, but the lack of reliable non-invasive measurements has been a major technical challenge. We recently developed a clinical method using optical coherence tomography time-lapse imaging and automated choroidal segmentation to measure the pulsatile choroidal volume change (...
Article
Full-text available
Purpose To report the first successfully treated case of recurrent tube exposure in a patient with the Boston Keratoprosthesis type 1 with a collagen matrix patch graft (Ologen). Observations A 50 year-old female with a Boston Keratoprosthesis type 1 and a history of Axenfeld-Reiger syndrome presents to our department with recurrent glaucoma drain...
Article
Purpose: To describe the surgical technique and outcomes in eyes that underwent surgery to replace a failed Ahmed valve by a Baerveldt glaucoma implant in the same quadrant. Methods: This study was a retrospective case series of 9 patients. Parameters analyzed include age, glaucoma type, prior surgery, complications, intraocular pressure (IOP),...
Article
Full-text available
The identification of modifiable risk factors for glaucoma progression is needed. Our objective was to determine whether maladaptive coping styles are associated with recent glaucoma progression or worse visual field mean deviation. A hospital-based case–control study was conducted in the Glaucoma Service of Maisonneuve-Rosemont Hospital in Montrea...
Chapter
Vascular disorders in the eye may have an important role in the pathogenesis of glaucomatous optic neuropathy. A primary requirement for understanding such vascular disorders is the ability to precisely and reliably evaluate the state of ocular perfusion in health and disease. This has led to the exploration of many innovative and diverse technique...
Chapter
A great body of evidence suggests that abnormal ocular blood flow contributes to the pathophysiology of open-angle glaucoma. Large clinical studies have linked low ocular perfusion pressure to the prevalence, incidence, and progression of glaucoma. Reduced blood flow has been reported in the retina, optic nerve, choroid and retrobulbar vasculature...
Article
Purpose: To compare rim area rates in patients with and without the visual field (VF) progression endpoint in the Canadian Glaucoma Study and determine whether intraocular pressure (IOP) reduction following the endpoint altered rim area rate. Design: Prospective multi-centre cohort study. Methods: Setting: University hospitals. Patient popula...
Article
Purpose: To determine whether two sessions of a glaucoma educational intervention resulted in better persistence to glaucoma eye drop therapy compared to normal care. Methods: A total of 165 patients newly diagnosed with glaucoma who required eye drop therapy were recruited into a randomized clinical trial from the glaucoma clinic at Maisonneuve...
Article
Optical coherence tomography (OCT) imaging has become a standard diagnostic tool in ophthalmology, providing essential information associated with various eye diseases. In order to investigate the dynamics of the ocular fundus, we present a simple and accurate automated algorithm to segment the inner limiting membrane in video-rate optic nerve head...
Article
Full-text available
We have developed a novel optical approach to determine pulsatile ocular volume changes using automated segmentation of the choroid, which, together with Dynamic Contour Tonometry (DCT) measurements of intraocular pressure (IOP), allows estimation of the ocular rigidity (OR) coefficient. Spectral Domain Optical Coherence Tomography (OCT) videos wer...
Article
To determine clinical factors and ultrasound biomicroscopic (UBM) findings associated with a positive prone dark-room provocative test (DRPT) in patients with narrow angles after laser peripheral iridotomy (LPI). Seventeen eyes with a positive DRPT and 18 eyes with a negative DRPT were included in this comparative case series, based on chart review...
Article
Among bone marrow cells, hematopoietic and mesenchymal components can contribute to repair damaged organs. Such cells are usually used in acute diseases but few options are available for the treatment of chronic disorders. In the present study, we have used a laser-induced model of open angle glaucoma (OAG) to evaluate the potential of bone marrow...
Article
Full-text available
Recent studies have shown that ocular hemodynamics and eye tissue biomechanical properties play an important role in the pathophysiology of glaucoma. Nevertheless, better, non-invasive methods to assess these characteristics in vivo are essential for a thorough understanding of degenerative mechanisms. Here, we propose to measure ocular tissue move...
Article
Full-text available
The purpose of this work was to investigate the heritability of potential glaucoma endophenotypes. We estimated for the first time the heritability of the pulsatility of choroidal blood flow. We also sought to confirm the heritability of corneal hysteresis, central corneal thickness, and 3 ways of measuring intraocular pressure. Measurements were p...
Data
A-Scans of the macula for the two extremes of the movement cycle. (DOCX)
Data
A-Scans of the optic disc for the two extremes of the movement cycle. (DOCX)
Article
Purpose: Theoretical models and animal studies have suggested that scleral rigidity plays an important role in the pathogenesis of glaucoma. The aim of this study was to present a noninvasive technique for estimating ocular rigidity (E) in vivo, and to compare the estimated rigidity between patients with open-angle glaucoma (OAG); ocular hypertens...
Article
Full-text available
Purpose: To measure the pulsatile movement of neuroretinal tissue at the optic nerve head synchronous with the cardiac cycle. Methods: We used a noninvasive imaging device based on Fourier domain low-coherence interferometry to measure the pulsatile movements of the optic nerve head, peripapillary retina, and cornea with submicron accuracy along...
Article
Full-text available
Purpose. To study the response to Selective Laser Trabeculoplasty (SLT) according to baseline medical treatment, angle pigmentation, age, diagnosis (open-angle glaucoma or ocular hypertension), and baseline intraocular pressure (IOP). Methods. 74 eyes of 74 patients were enrolled in this study. Baseline characteristics were recorded for each patie...
Article
Purpose: To assess changes in Scheimpflug-based measurements of the anterior segment after pilocarpine administration and prophylactic laser peripheral iridotomy in narrow anterior chamber angles. Methods: Thirty-seven eyes in 37 patients with occludable angles were included in this prospective interventional case series. Primary angle-closure s...
Article
Purpose: To present 4 cases of persistent leak attributed to subconjunctival fistula formation after glaucoma aqueous shunt implantation. Our preferred method for management is also described. Methods: Retrospective noncomparative case series. Results: Four cases of persistent leak after glaucoma aqueous shunt surgery are described. Three pati...
Article
Full-text available
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 mod...
Article
Anomalies in the pulsatility of the eye have been associated with many types of ocular pathology. Estimation of ocular pulsatility is usually obtained by measuring the variation in the intraocular pressure using tonometry-based instruments. In this work, the authors present and demonstrate the applicability of a novel and noninvasive Fourier-domain...
Article
Intravitreal (ITV) injection of anti-VEGFs like bevacizumab are widely used to treat neovascular AMD. However, VEGF is essential for biologic functions such as blood pressure regulation. Indeed, anti-VEGF intravenous administration is associated with hypertension. Therefore, the effect of ITV bevacizumab on retinal circulation was examined. Twenty-...
Article
In this work we demonstrate the use of two-dimensional detectors to improve the signal-to-noise ratio (SNR) and sensitivity in spectral-domain phase microscopy for subnanometer accuracy measurements. We show that an increase in SNR can be obtained, from 82 dB to 105 dB, using 150 pixel lines of a low-cost CCD camera as compared to a single line, to...
Article
To determine if the difference in intraocular pressure (IOP) measurements between dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) is correlated with axial length (AL), and to assess the possible influence of age, sex, central corneal thickness (CCT), corneal hysteresis (CH), ocular pulse amplitude (OPA), and glaucoma status...
Article
Full-text available
To determine rates of visual field change associated with risk factors for progression in the Canadian Glaucoma Study (abnormal anticardiolipin antibody level, age, female sex, and mean follow-up intraocular pressure [IOP]), and to evaluate the effect of IOP reduction on subsequent rates of visual field change in progressing patients. Two hundred s...
Article
Purpose In an attempt to understand some of the reasons why some optic nerves appear to be sensitive to IOP and others not, I will review studies describing the interaction between vascular and biomechanical factors in open angle glaucoma.Methods Studies using biomechanical modelling, epidemiologic data, measurements of ocular or systemic blood flo...
Article
We demonstrate an optical instrument that can measure the axial displacement of different eye tissues, including the cornea and the fundus. The instrument is based on spectral-domain low-coherence interferometry, which extracts displacement information from sequential axial scans of the eye with 100 Hz sampling frequency and with a precision of 400...
Article
To investigate whether postmenopausal hormone therapy (HT) increases retinal and ONH blood flow (BF) and protects ONH topography and the function of retinal ganglion cells in postmenopausal women (PMW). The effect of estradiol (E(2)) treatment on retinal tissue perfusion was also investigated in ovariectomized rats, an animal model for menopause. S...
Article
Full-text available
To report 4 cases of recurrent anterior uveitis occurring 1-11 months after trabeculectomy with mitomycin C. Observational case series. Four patients in whom recurrent uveitis developed after trabeculectomy with mitomycin C, followed at Maisonneuve-Rosemont Hospital in Montreal, Quebec. Retrospective review of the medical records. One to 11 months...
Article
Quantitative and regional measurement of retinal blood flow in rodents is of prime interest for the investigation of regulatory mechanisms of ocular circulation in physiological and pathological conditions. In this study, a quantitative autoradiographic method using N-isopropyl-p-(14)C-iodoamphetamine ([(14)C]-IMP), a diffusible radioactive tracer,...
Article
We describe a new instrument developed for the study and diagnosis of glaucoma. This device is based on Fourier domain low coherence interferometry for in vivo measurement of the retinal movements, to assess in real-time the biomechanical properties of the eye. By measuring the displacement of the retina in a live rat, we show that the instrument h...
Article
Estimate patient adherence to glaucoma medications and identify potential determinants of nonadherence. Descriptive study. Two hundred patients with open angle glaucoma, ocular hypertension, or glaucoma suspects were interviewed regarding their glaucoma and its treatment and their charts were reviewed. Their ophthalmologist completed a brief assess...
Article
Full-text available
To determine systemic and ocular risk factors for visual field progression in open-angle glaucoma. In the Canadian Glaucoma Study, a multicenter prospective longitudinal study of 258 patients (131 men and 127 women; median age, 65.0 years), baseline systemic measures included assessment of peripheral vasospasm and markers for hematopathology, coagu...
Article
This article reviews the effects of systemic medications and some native vasoactive molecules on ocular blood flow (OBF). Some evidence exists for a positive effect of centrally acting calcium-channel blockers, nitric oxide precursors, adenosine, histamine, estrogens, and ginkgo biloba extract, while evidence for a negative effect on OBF exists for...
Article
Full-text available
Treatment of glaucoma is aimed at reducing intraocular pressure (IOP) to prevent further damage to the optic nerve. For patients who do not respond to monotherapy, combination treatment may be effective in achieving therapeutic reduction or target IOP. To evaluate the effectiveness and safety of dorzolamide 2% with timolol 0.5% alone or combined wi...
Article
With the aging of the population, age-related macular degeneration (AMD) is becoming a public health concern. Few studies have assessed its consequences on morbidity and mortality, and the findings are conflicting. To assess the risk of depression, fracture, institutionalization, and death among elderly patients with suspected exudative AMD and the...
Article
To investigate changes in optic nerve head topography and blood flow after therapeutic intraocular pressure reduction and to correlate them with central corneal thickness. Sixteen patients with open-angle glaucoma and 16 patients with ocular hypertension underwent Heidelberg retina tomography and scanning laser Doppler flowmetry in 1 eye before and...
Article
Background: The Canadian Glaucoma Study is a multicentred, prospective longitudinal study designed to study a variety of systemic risk factors for the progression of open-angle glaucoma under a standardised interventional protocol for intraocular pressure (IOP) control. Methods: Newly or previously diagnosed patients with early to moderate open-ang...
Article
To evaluate whether confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph II [HRT II], Heidelberg Engineering, Heidelberg, Germany) is a valid tool for the detection of glaucomatous optic nerve damage. Observational, cross-sectional, nonconsecutive study in Montreal, Canada. Three hundred three nonconsecutive, high-risk persons were e...
Article
To correlate finger blood flow and changes in optic nerve head (ONH) blood flow following therapeutic intraocular pressure (IOP) reduction in open-angle glaucoma (OAG) and ocular hypertension (OHT). Seventeen open-angle glaucoma patients and nineteen ocular hypertension patients underwent therapeutic IOP reduction followed by a minimum of 4 weeks o...
Article
To report and assess the complication of intraocular pressure (IOP) elevations after selective laser trabeculoplasty (SLT) in patients with heavily pigmented trabecular meshworks. Noncomparative, observational case series. Retrospective analysis of the medical files of four glaucoma patients with heavily pigmented trabecular meshwork, who presented...
Article
To evaluate the effectiveness of phacoemulsification and goniosynechialysis (PEGS) in managing acute and subacute primary angle closure unresponsive to conventional therapy. Retrospective series of patients of six glaucoma-trained surgeons with primary angle closure that did not respond to medical management, Nd:YAG laser peripheral iridotomy, or a...
Article
To evaluate the efficacy and safety of intraoperative mitomycin C (MMC) in eyes undergoing Ahmed Glaucoma Valve implantation. Randomized controlled clinical trial. Sixty patients with refractory glaucoma. Sixty eyes of 60 patients with refractory glaucoma were randomized to receive intraoperative MMC (0.5 mg/ml for 5 minutes) (n = 34) or balanced s...
Article
To compare optic nerve head (ONH) and peripapillary retinal blood flow in subjects with open-angle glaucoma (OAG), ocular hypertension (OHT), and normal eyes (NOR) using full-field perfusion analysis of scanning laser Doppler flowmetry (SLDF) images. Prospective, nonrandomized clinical trial. Twenty uncontrolled OAG patients, 20 uncontrolled OHT pa...
Article
To evaluate the reproducibility of full-field perfusion analysis using scanning laser Doppler flowmetry (SLDF) for perfusion measurements of the neuroretinal rim of the optic nerve head and the peripapillary retina in patients with open-angle glaucoma or ocular hypertension, and in normal subjects. SLDF perfusion measurements of the neuroretinal ri...
Article
To detect and quantify changes in optic nerve head (ONH) and peripapillary retinal blood flow by scanning laser Doppler flowmetry (SLDF) in open-angle glaucoma (OAG) and ocular hypertension (OHT) after therapeutic intraocular pressure (IOP) reduction. Prospective, nonrandomized, self-controlled trial. Twenty patients with OAG and 20 patients with O...
Article
Several new agents for the topical therapy of glaucoma have recently become available in Canada. While these medications all reduce intraocular pressure, there is also evidence that some may improve ocular blood flow. We review the ocular hypotensive and ocular blood flow effects of these newer agents.
Article
To investigate whether dorzolamide alters corneal hydration control in patients with glaucoma or ocular hypertension. Pachymetry, tonometry, and endothelial cell density were measured by a masked observer in 19 subjects with bilateral glaucoma or ocular hypertension. They were treated with 2% dorzolamide in one eye, and with saline in the other, be...
Article
To determine the chemical stability of various mitomycin C (MMC) solutions used in glaucoma filtering surgery. A survey of the MMC solutions currently in use in 21 hospitals (11 in Canada, 10 in the United States) was conducted. A comparative study of the chemical stability of five different representative solutions was performed. The effects of bu...
Article
To detect and quantitate changes in optic nerve morphology after glaucoma surgery using the Heidelberg Retina Tomograph (HRT, Heidelberg Instruments, Heidelberg, Germany). Nonconsecutive observational case series. The authors prospectively enrolled 21 adult patients undergoing incisional glaucoma surgery for progressive glaucoma damage. Quantitativ...
Article
Both apraclonidine hydrochloride 0.5% and brimonidine tartrate 0.5% are potent alpha-2 agonists, effective in controlling the intraocular pressure (IOP) rise following argon laser trabeculoplasty (ALT). Brimonidine has recently become available commercially as a 0.2% solution. Our goal in this study was to compare the efficacy and side effect profi...
Article
Purpose. Thalidomide is anti-angiogenic in the rabbit cornea model. We studied the survival of sclerostomies performed in 12 eyes of 10 rabbits treated with thalidomide or placebo. Seven eyes also received 5-FU to complementarity diminish fibroblast function. Methods. In a blinded randomized protocol, full thickness sclerostomies were performed und...
Article
We evaluated the influence of apraclonidine on the outcome of filtering surgery. Patients treated with apraclonidine who underwent a guarded filtration procedure were retrospectively evaluated and compared to a control group. Complications were more frequent in patients treated with apraclonidine than in the control group, but the difference was no...
Article
Purpose: To compare corneal endothelial cell loss after intermediate follow-up of phacoemulsification, trabeculectomy and combined procedures. Methods: We investigated 25 eyes from 25 patients, 10 undergoing phacoemulsification, 8 trabeculectomy and 7 combined phaco-trabeculectomy. Specular microscopy was performed before, at 12 and 36 months after...
Article
We examined ciprofloxacin levels in the aqueous humor, vitreous, or subretinal fluid in 40 patients undergoing cataract extraction, vitrectomy, or scleral buckling. Ciprofloxacin, 750 mg, was administered orally an average of 17 1/2 and 5 1/2 hours preoperatively. We obtained mean ciprofloxacin levels of 0.53 microgram/ml in aqueous humor, 0.51 mic...
Article
Expression of many cell type-specific genes is correlated with a reduced level of cytosine methylation and some results argue that genetic programmes may be activated by a reduction in DNA methylation. During embryogenesis, however, when many genes are activated in specific cell lineages, it has not been demonstrated that they are hypomethylated pr...

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