Papers by Jean-marie Parel
Ophthalmic Technologies, 1991
Photodynamic therapy (PDT) eiiploying Dihematopor* iyrin ethers (DHE)(Photofrin II) at pharmacolo... more Photodynamic therapy (PDT) eiiploying Dihematopor* iyrin ethers (DHE)(Photofrin II) at pharmacologic lvels, has been denonstrate3 to kill rabbitlens epithelial cells, in vivo. This in vitro study, reports on theminimal necessary parameters for rabbit lens epithelial cell ...
Investigative ophthalmology & visual science, 2015
To determine if the lens volume changes during accommodation. The study used data acquired on 36 ... more To determine if the lens volume changes during accommodation. The study used data acquired on 36 cynomolgus monkey lenses that were stretched in a stepwise fashion to simulate disaccommodation. At each step, stretching force and dioptric power were measured and a cross-sectional image of the lens was acquired using an optical coherence tomography system. Images were corrected for refractive distortions and lens volume was calculated assuming rotational symmetry. The average change in lens volume was calculated and the relation between volume change and power change, and between volume change and stretching force, were quantified. Linear regressions of volume-power and volume-force plots were calculated. The mean (±SD) volume in the unstretched (accommodated) state was 97 ± 8 mm3. On average, there was a small but statistically significant (P = 0.002) increase in measured lens volume with stretching. The mean change in lens volume was +0.8 ± 1.3 mm3. The mean volume-power and volume-...
Biomedical optics express, 2018
We present a new instrument for measuring shape and wavefront aberrations of the primate crystall... more We present a new instrument for measuring shape and wavefront aberrations of the primate crystalline lens, both on- and off-axis, while simulating accommodation with a motorized lens stretching system. The instrument merges spectral domain optical coherence tomography (SD-OCT) imaging and ray tracing aberrometry using an approach that senses wavefront aberrations of the lens with the OCT probing beam. Accuracy and repeatability of aberration measurements were quantified. Preliminary experiments on two human and four cynomolgus monkey lenses demonstrate the ability of the system to measure the lens shape, spherical aberration and peripheral defocus, and their changes during simulated accommodation.
Biomedical optics express, 2018
Optical coherence tomography (OCT) offers new options for imaging the ciliary muscle allowing dir... more Optical coherence tomography (OCT) offers new options for imaging the ciliary muscle allowing direct visualization. However, variation in image quality along the length of the muscle prevents accurate delineation and quantification of the muscle. Quantitative analyses of the muscle are accompanied by variability in segmentation between examiners and between sessions for the same examiner. In processes such as accommodation where changes in muscle thickness may be tens of microns- the equivalent of a small number of image pixels, differences in segmentation can influence the magnitude and potentially the direction of thickness change. A detailed analysis of variability in ciliary muscle thickness measurements was performed to serve as a benchmark for the extent of this variability in studies on the ciliary muscle. Variation between sessions and examiners were found to be insignificant but the magnitude of variation should be considered when interpreting ciliary muscle results.
Investigative ophthalmology & visual science, 2018
To characterize the peripheral defocus of the monkey crystalline lens and its changes with accomm... more To characterize the peripheral defocus of the monkey crystalline lens and its changes with accommodation. Experiments were performed on 15 lenses from 11 cynomolgus monkey eyes (age: 3.8-12.4 years, postmortem time: 33.5 ± 15.3 hours). The tissue was mounted in a motorized lens stretcher to allow for measurements of the lens in the accommodated (unstretched) and unaccommodated (stretched) states. A custom-built combined laser ray tracing and optical coherence tomography system was used to measure the paraxial on-axis and off-axis lens power for delivery angles ranging from -20° to +20° (in air). For each delivery angle, peripheral defocus was quantified as the difference between paraxial off-axis and on-axis power. The peripheral defocus of the lens was compared in the unstretched and stretched states. On average, the paraxial on-axis lens power was 52.0 ± 3.4 D in the unstretched state and 32.5 ± 5.1 D in the stretched state. In both states, the lens power increased with increasing...
Biomedical optics express, 2017
It has been suggested that accommodation induces increases in axial eye length which could contri... more It has been suggested that accommodation induces increases in axial eye length which could contribute to the development of myopia. However, it is debated whether changes in eye length occur during accommodation as the degree of change varies widely across literature. In this study, an extended-depth optical coherence tomography (OCT) system that provides dynamic whole eye biometry was utilized to assess changes in lens thickness (LT) and axial eye length (AEL) in young subjects responding to step disaccommodation stimuli of amplitude 2D, 4D, and 6D. The decrease in lens thickness with disaccommodation was strongly correlated with stimulus amplitude. No statistically significant changes in AEL during accommodation were observed.
Scientific reports, Mar 2, 2017
Proliferative vitreoretinopathy (PVR) is mediated by proliferation and epithelial mesenchymal tra... more Proliferative vitreoretinopathy (PVR) is mediated by proliferation and epithelial mesenchymal transition (EMT) of retinal pigment epithelium (RPE). Because heavy chain-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) purified from human amniotic membrane exerts anti-inflammatory and anti-scarring actions, we hypothesized that HC-HA/PTX3 could inhibit these PVR-related processes in vitro. In this study, we first optimized an ARPE-19 cell culture model to mimic PVR by defining cell density, growth factors, and cultivation time. Using this low cell density culture model and HA as a control, we tested effects of HC-HA/PTX3 on the cell viability (cytotoxicity), proliferation (EGF + FGF-2) and EMT (TGF-β1). Furthermore, we determined effects of HC-HA/PTX3 on cell migration (EGF + FGF-2 + TGF-β1) and collagen gel contraction (TGF-β1). We found both HA and HC-HA/PTX3 were not toxic to unstimulated RPE cells. Only HC-HA/PTX3 dose-dependently inhibited proliferation and EMT of stimulated RPE cells by...
American Journal of Ophthalmology, 2016
Venous air embolism (VAE) during pars plana vitrectomy (PPV) can occur due to improper positionin... more Venous air embolism (VAE) during pars plana vitrectomy (PPV) can occur due to improper positioning of the infusion cannula in the suprachoroidal space and may lead to sudden compromise of cardiac circulation and death. In vivo demonstration of fatal VAE during PPV showing air can travel from the suprachoroidal space into the central circulation. Experimental in vivo surgical study on porcine eyes. Experimental PPV under general anesthesia was performed on porcine eyes (Yorkshire species) at a University Surgical Training & Education Center. Infusion cannulas were placed into the suprachoroidal space and fluid air exchange (FAE) was started with sequential increases in infusion air pressure. Vital signs of porcine animals were continuously monitored and recorded in real time during the PPV, including end-tidal CO2 (ETCO2), oxygen saturation (SaO2), intra-arterial blood pressure, electrocardiography (EKG), and trans-esophageal echocardiography (TEE). Intracardiac air was detected on TEE less than 30 seconds after increasing air infusion pressure to 60 mm Hg. ETCO2 declined precipitously, followed by hypotension and EKG changes. Oxygen desaturation was a late phenomenon. The animal died within 7 minutes of VAE. During autopsy, the heart was open under water and air escaped from the right ventricle. This in vivo porcine model confirms that during the FAE in PPV, pressurized air from an infusion cannula malpositioned in the suprachoroidal space, can transit through the eye to the central circulation, resulting in fatal VAE.
Regenerative biomaterials, 2016
The InnFocus MicroShunt® is a minimally invasive glaucoma drainage microtube used to shunt aqueou... more The InnFocus MicroShunt® is a minimally invasive glaucoma drainage microtube used to shunt aqueous humor from the anterior chamber of the eye to a flap formed under the conjunctiva and Tenon's capsule. The safety and clinical performance of this device approaches that of trabeculectomy with mitomycin C, the current 'gold standard' treatment for advanced glaucoma. The invention of a new biomaterial called poly(styrene-block-isobutylene-block-styrene) or 'SIBS' is the enabling factor which led to the success of this product. SIBS is ultrastable with virtually no foreign body reaction in the body, which manifests as clinically insignificant inflammation and capsule formation in the eye. The lack of capsule formation enables unobstructed flow through the 70 µm lumen tube and the achievement of controlled low intraocular pressure, which is important for the management of glaucoma. This article summarizes the integration of SIBS into a glaucoma drainage device and conf...
American journal of ophthalmology, Jan 22, 2016
To evaluate the in vitro efficacy of rose bengal- and riboflavin- mediated photodynamic therapy f... more To evaluate the in vitro efficacy of rose bengal- and riboflavin- mediated photodynamic therapy for inhibition of methicillin-resistant Staphylococcus aureus (MRSA) isolates. Experimental study METHODS: Two different multidrug-resistant, clinical MRSA isolates were grown on nutrient agar, prepared in suspension and adjusted to concentrations of 1.5 x 10(4) cfu/mL. Bacterial suspensions were mixed with rose bengal, riboflavin, or water according to experimental group. Tested in triplicate, groups included: Group I: MRSA control, Group II: MRSA with 0.1% rose bengal, Group III: MRSA with 0.03% rose bengal, and Group IV: MRSA with 0.1% riboflavin. All experimental groups were exposed to three lighting conditions: dark, ambient room light for 30 minutes, and 5.4 J/cm(2) with either green light-emitting diode (LED) or ultra violet- A (UV-A) irradiation. Plates were photographed at 72 hours and custom software measured bacterial growth inhibition. Complete growth inhibition of both MRSA s...
Biomedical Optics Express, 2016
Two SD-OCT systems and a dual channel accommodation target were combined and precisely synchroniz... more Two SD-OCT systems and a dual channel accommodation target were combined and precisely synchronized to simultaneously image the anterior segment and the ciliary muscle during dynamic accommodation. The imaging system simultaneously generates two synchronized OCT image sequences of the anterior segment and ciliary muscle with an imaging speed of 13 frames per second. The system was used to acquire OCT image sequences of a non-presbyopic and a pre-presbyopic subject accommodating in response to step changes in vergence. The image sequences were processed to extract dynamic morphological data from the crystalline lens and the ciliary muscle. The synchronization between the OCT systems allowed the precise correlation of anatomical changes occurring in the crystalline lens and ciliary muscle at identical time points during accommodation. To describe the dynamic interaction between the crystalline lens and ciliary muscle, we introduce accommodation state diagrams that display the relation between anatomical changes occurring in the accommodating crystalline lens and ciliary muscle.
Journal of glaucoma, Jan 13, 2016
An observational study to determine the safety and efficacy of filtering surgery employing a micr... more An observational study to determine the safety and efficacy of filtering surgery employing a microlumen aqueous drainage device (InnFocus MicroShunt), used intraoperatively with Mitomycin C, implanted alone or in combination with phacoemulsification. Single-site, prospective, nonrandomized study of 23 eyes that had failed maximum tolerated glaucoma medication, followed for 3 years. A MicroShunt was implanted ab externo through a needle tract under the limbus, draining aqueous from the anterior chamber to the scleral surface. Prespecified outcome measures include: intraocular pressure (IOP) control, with and without supplemental medication, success rate, medication use, and adverse events. Fourteen patients received the MicroShunt alone and 9 with cataract surgery. At 1 (n=23), 2 (n=22), and 3 (n=22) years of follow-up; the qualified success rate (IOP≤14 mm Hg and IOP reduction ≥20%) was 100%, 91%, and 95%; mean medicated IOP was reduced from 23.8±5.3 to 10.7±2.8, 11.9±3.7, and 10.7±...
Biomedical Optics Express, 2015
We present a method for measuring lens power from extended depth OCT biometry, corneal topography... more We present a method for measuring lens power from extended depth OCT biometry, corneal topography, and refraction using an improvement on the Bennett method. A reduced eye model was used to derive a formula for lens power in terms of ocular distances, corneal power, and objective spherical equivalent refraction. An error analysis shows that the formula predicts relaxed lens power with a theoretical accuracy of ± 0.5 D for refractive error ranging from -10 D to + 10 D. The formula was used to calculate lens power in 16 eyes of 8 human subjects. Mean lens power was 24.3 D ± 1.7 D.
MRS Proceedings, 2002
ABSTRACTThe hydrophilic group was substituted with separation distance of 100μm in a porous poly-... more ABSTRACTThe hydrophilic group was substituted with separation distance of 100μm in a porous poly-tetrafluoroethylene (PTFE) membrane by ArF laser irradiation. With the micro domain structure of hydrophilic and hydrophobic groups in the porous PTFE, the membrane was modified to be fibrin and fat- free. Furthermore, the differential osmotic pressure was controlled freely by changing the density of the hydrophilic group into the porous PTFE. As a result, we developed the glaucoma implant membrane that is free from fibrin and fat and inhibits the graft rejection in the human body.
Ophthalmic Technologies XIV, 2004
Purpose. The purpose of this study was to evaluate if changes in the aberration-contribution of t... more Purpose. The purpose of this study was to evaluate if changes in the aberration-contribution of the internal optics of the eye have a significant effect on the outcome of wavefront-guided corneal reshaping. Methods. The Navarro-Escudero eye model was simulated using optical analysis software. The eye was rendered myopic by shifting the plane of the retina. Custom-LASIK was simulated by changing the radius of curvature and asphericity of the anterior corneal surface of the eye model. The radius of curvature was adjusted to provide a retinal conjugate at infinity. Three approaches were used to determine the postoperative corneal asphericity: minimizing third-order spherical aberration, minimizing third-order coma, and maximizing the Strehl ratio. The aberration contribution of the anterior corneal surface and internal optics was calculated before and after each simulated customized correction. Results. For a 5.2mm diameter pupil, the contribution of the anterior corneal surface to third-order spherical aberration and coma (in micrometers) was 2.22 and 2.49 preop, -0.36 and 2.83 postop when spherical aberration is minimized, 5.88 and 1.10 postop when coma is minimized, and -0.63 and 2.91 postop when Strehl ratio is maximized. The contribution of the internal optics of the eye to spherical aberration and coma for the same four conditions was: 0.43 and -1.13, 0.37 and -1.10, 0.37 and -1.10 and 0.37 and -1.10, respectively. Conclusion. In the model eye, the contribution of the internal optics of the eye to the change in the ocular aberration state is negligible.
American journal of ophthalmology, Jan 15, 1987
Biomedical optics express, 2012
An optical switch was implemented in the reference arm of an extended depth SD-OCT system to sequ... more An optical switch was implemented in the reference arm of an extended depth SD-OCT system to sequentially acquire OCT images at different depths into the eye ranging from the cornea to the retina. A custom-made accommodation module was coupled with the delivery of the OCT system to provide controlled step stimuli of accommodation and disaccommodation that preserve ocular alignment. The changes in the lens shape were imaged and ocular distances were dynamically measured during accommodation and disaccommodation. The system is capable of dynamic in vivo imaging of the entire anterior segment and eye-length measurement during accommodation in real-time.
Ophthalmic Technologies III, 1993
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Papers by Jean-marie Parel