Jean-Marie Parel

University of Miami | UM · Department of Ophthalmology / Bascom Palmer Eye Institute

We measured the average group refractive index (RI) of 120 isolated lenses from 120 human donors (age: 0.03 to 61 years). The average group RI was calculated from a measurement of the optical thickness of the lens using optical coherence tomography and the apparent window shift of the test chamber caused by the lens. The estimated measurement uncer...

Aim: Rose Bengal photodynamic antimicrobial therapy (RB-PDAT) has poor corneal penetration, limiting its efficacy against acanthamoeba keratitis (AK). Iontophoresis enhances corneal permeation of charged molecules, piquing interest in its effects on RB in ex vivo human corneas. Methods: Five donor whole globes each underwent iontophoresis with RB,...

Accommodation is the process by which the eye changes focus. These changes are the result of changes to the shape of the crystalline lens. Few prior studies have quantified the relation between lens shape and ocular accommodation, primarily at discrete static accommodation states. We present an instrument that enables measurements of the relation b...

We present proof of concept for a handheld contact-type system capable of simultaneous optical coherence tomography (OCT) imaging of the retina and wide-field digital fundus color photography. The study focuses on demonstrating the feasibility of the proposed approach, particularly for eventual use in pediatric patients during examination under ane...

The purpose is to assess the efficacy of rose bengal photodynamic antimicrobial therapy (PDAT) using different irradiation energy levels and photosensitizer concentrations for the inhibition of fungal keratitis isolates. Seven different fungi (Aspergillus fumigatus, Candida albicans, Curvularia lunata, Fusarium keratoplasticum, Fusarium solani, Pae...

Purpose : Studies have shown a degradation of peripheral retinal image quality in pseudophakic eyes, which can affect visual function. The goal of this study is to measure the peripheral defocus profile of monofocal intraocular lenses (IOLs) and compare it with theoretical predictions. Methods : Peripheral defocus profiles of monofocal spherical (...

Purpose : To study the age-dependence of the human lens refractive index (RI) and its implication for the refractive index profile. Methods : Measurements were taken on 91 isolated lenses from 91 human donors (age: 0.03 to 55 years). Lenses were immersed in balance salt solution (BSS) in the test chamber of an 880nm spectral-domain Optical Coheren...

Purpose: To determine whether lens mechanical dynamics change with age and with accommodative demands. Methods: Lens thickness microfluctuations were measured using a high-speed custom-built spectral domain optical coherence tomography system in five young adults (20 to 25 years old) at 0 diopters (D), 2 D, 4 D, and maximum accommodative demand...

Purpose To evaluate the intermediate term clinical outcomes of Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT) for infectious keratitis. Secondarily, to evaluate the surgical outcomes of individuals that underwent optical keratoplasty after RB-PDAT. Design Retrospective cohort study. Methods Retrospective chart review of 31 eyes from 30...

Purpose: To determine whether patient-customized paraxial eye models that do not rely on exact ray-tracing and do not consider aberrations can accurately predict pseudophakic refraction. Setting: Bascom Palmer Eye Institute, Miami, FL, USA. Design: Prospective study. Methods: Cataract surgery patients with and without a history of refractive...

Purpose To report the increasing trends in Nocardia keratitis species diversity and in vitro antibiotic susceptibility, to demonstrate contact lens wear as a risk factor, and to report visual acuity outcomes after treatment. Methods A retrospective clinical case series was performed at a single academic referral center which identified 26 patients...

This study demonstrates the feasibility of using OCT to quantify microfluctuations in ocular biometry at steady-state accommodation. The preliminary results confirm the presence of two main frequency components in mechanical fluctuations of the lens consistent with prior studies on microfluctuations of optical accommodation (LFC: ≤ 0.6Hz and HFC: 1...

Purpose To determine the effect of temperature on the accommodative response of non-human primate crystalline lenses during simulated accommodation. Methods Eight lenses from 7 cynomolgus monkeys (Macaca fascicularis, ages: 4.5–7.3 years; post-mortem time: 17.0 ± 16.4 h) were mounted in a lens stretcher. Stretching experiments were performed on ea...

Purpose To evaluate the visual photosensitivity threshold and objective photosensitivity luminance in healthy eyes, thereby providing a normative dataset that will lead to a better understanding of diseases causing photophobia. Methods This was a prospective cross-sectional study. Emmetropes whose visual acuity was better than 0.18 logMAR (6/9) wi...

We have combined an anterior segment (AS) optical coherence tomography (OCT) system and a wavefront-based aberrometer with an approach that senses ocular wavefront aberrations using the OCT beam. Temporal interlacing of the OCT and aberrometer channels allows for OCT images and refractive error measurements to be acquired continuously and in real-t...

The mouse lens is frequently used both in vivo and ex vivo in ophthalmic research to model conditions affecting the human lens, such as presbyopia. The mouse lens has a delicate structure which is prone to damage and biomechanical changes both before and after extraction from the whole globe. When not properly controlled for, these changes can conf...

Background Methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant (MDR) S. aureus strains are well recognized as posing substantial problems in treating ocular infections. S. aureus has a vast array of virulence factors, including superantigens and enterotoxins. Their interactions and ability to signal antibiotics resistance hav...

We acquired 1325 nm OCT images of the sclera and ciliary muscle of human subjects. The attenuation coefficients of the sclera and ciliary muscle were determined from a curve fit of the average intensity profile of about 100 A-lines in a region of interest after correction for the effect of beam geometry, using a single scattering model. The average...

Purpose : Defocus in the periphery of the retinal image field maybe a factor in refractive development. Peripheral defocus is generally attributed to changes in globe shape or axial length. However, age-related changes in crystalline lens shape and optics may also be a factor. The goal is to quantify the lens contribution to the shape of the retina...

Purpose : To evaluate the peripheral defocus of monofocal intraocular lenses (IOLs), thereby quantifying the accuracy of laser ray tracing (LRT) measurements of peripheral defocus. Methods : Data were acquired on 14 polymethylmethacrylate spherical optic monofocal IOLs (overall length 12.5 mm, optic diameter 6.0 mm). The power (D) of the IOLs used...

Purpose: To evaluate the in vivo corneal changes after Rose Bengal photodynamic antimicrobial therapy (RB-PDAT) treatment in New Zealand White rabbits. Methods: Sixteen rabbits were divided into 5 groups. All groups underwent deepithelialization of an 8 mm diameter area in the central cornea. Group 1: balanced salt solution drops only, group 2:...

Purpose: To characterize the peripheral defocus of isolated human crystalline lenses and its age dependence. Methods: Data were acquired on 116 isolated lenses from 99 human eyes (age range, 0.03-61 years; postmortem time, 40.1 ± 21.4 hours). Lenses were placed in a custom-built combined laser ray tracing and optical coherence tomography system...

Rose bengal photodynamic antimicrobial therapy (RB-PDAT) treats corneal infection by activating rose bengal (RB) with green light to produce singlet oxygen (¹O2). Singlet oxygen dosimetry can help optimize treatment parameters. We present a ¹O2 dosimeter for detection of ¹O2 generated during experimental RB-PDAT. The system uses a 520 nm laser and...

Purpose of Review Due to the invasive nature of the keratoplasty and the shortage of available donor tissue around the world, alternative treatments are needed for the management of progressive infectious keratitis. Recent Findings Infectious keratitis is a sight-threatening microbial infection. The prevalence of antimicrobial resistance in cases...

Purpose To report photokeratitis caused by the improper use of germicidal lamps purchased during the COVID-19 pandemic. Methods Case series. Results Seven patients presented with acute ocular surface pain after exposure to UV-emitting germicidal lamps. Visual acuity was 20/30 or better in 13 of 14 eyes (93%). Anterior segment examination revealed...

There is a great need for accurate biometric data on human lenses. To meet this, a compact tabletop optical comparator, the minishadowgraph, was built for measuring isolated eye lens shape and dimensions while the lens was fully immersed in supporting medium. The instrument was based around a specially designed cell and an illumination system which...

Objective To validate the use of a mechanized remotely operated stereoscopic drone slit lamp (DSL) in assessing anterior segment pathology in ophthalmology patients compared with conventional slit lamp (CSL). Methods Patients were recruited from eye clinics at Hotel Dieu Hospital in Kingston, Ontario, Canada. Each patient was assessed by 2 examine...

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Purpose : It is well known that human crystalline lens biometry and optical properties change throughout life with age and influence whole eye refraction. However, it is not clear if lens equatorial diameter (LD) and lens power (LP) are associated with corneal and globe biometry. The purpose of the present study is to investigate the relationship b...

Purpose : Quantifying human crystalline lens geometry as a function of age and accommodation is essential for understanding disorders such as cataract and presbyopia. We estimated the geometry of the full shape of crystalline lens at different levels of accommodation simulated by a lens stretcher using optical coherence tomography (OCT). Methods :...

To evaluate the in vitro efficacy of rose bengal and riboflavin photodynamic antimicrobial therapy for inhibition the growth of four Pseudomonas aeruginosa (P. aeruginosa) isolates. Four different clinical P. aeruginosa isolates were collected from patients with confirmed keratitis. Each strain was mixed with either sterile water, 0.1% riboflavin s...

Vitreo-retinal surgical techniques have transformed since the introduction of pars plana vitrectomy in 1970. Advancements include smaller gauge instrumentation, faster cut rates, improved illumination methods, wider-field viewing systems, and the use of various tamponade agents and perfluorocarbon.

Purpose: To report clinical outcomes of Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT) as an adjunct treatment for severe, progressive infectious keratitis. Design: Consecutive interventional case series. Methods: Patients with progressive infectious keratitis unresponsive to standard medical therapy underwent RB-PDAT at the Bascom P...

Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT) is a novel potential treatment for progressive infectious keratitis. The principle behind this therapy is using Rose Bengal as a photosensitizer that can be activated by green light and results in the production of oxygen free radicals which in turn eradicate the microorganism. Given RB-PDAT'...

Purpose: To evaluate a new corneal cold storage medium including an antimycotic tablet (Kerasave, AL.CHI.MI.A. S.r.l.). Methods: Kerasave and tryptone soy broth (control) were inoculated with 10 and 10 colony-forming units (CFU)/mL of 6 Candida isolates (Candida albicans [n = 4], Candida tropicalis [n = 1], and Candida glabrata [n = 1]). Minimum...

Earlier studies have shown that the gradient index of refraction (GRIN) of the crystalline lens can be reconstructed in vitro using Optical Coherence Tomography (OCT) images. However, the methodology cannot be extended in vivo because it requires accurate measurements of the external geometry of the lens. Specifically, the posterior surface is meas...

Purpose: To report the long-term outcomes of three patients with infectious keratitis treated with riboflavin photodynamic antimicrobial therapy (PDAT). Observations: Case series reporting three patients with infectious keratitis unresponsive to standard medical treatment who underwent riboflavin photodynamic antimicrobial therapy (PDAT) as an a...

Aims/hypothesis Patients with autoimmune type 1 diabetes transplanted with pancreatic islets to their liver experience significant improvement in quality of life through better control of blood sugar and enhanced awareness of hypoglycaemia. However, long-term survival and efficacy of the intrahepatic islet transplant are limited owing to liver-spec...

Accurate quantification of the full shape of the human eye lens is essential for understanding how eye sees object at various distances and age-related disorders such as loss of near vision and clouding of the lens. In this study, we propose a new method that provides a more compact, intuitive and accurate representation of the full shape of the le...

The human eye lens grows continuously throughout life and plays an important role in the development of age-related vision problems such as loss of near sight (presbyopia) or clouding of the lens (cataract). We developed a new technology that can directly study both the three-dimensional shape of the eye lens and the way light is bent in lenses as...

Purpose To characterize the molecular, epidemiological, and resistance profiles of methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) keratitis isolates. Patients and methods We used a combination of standard microbiological techniques and DNA microarray analysis to characterize the molecular and antibiotic resistance profiles of 75 S...

We describe the application of the Ray-Tracing Aberrometry to the measurement of lens spherical aberration using a recently developed instrument (Ruggeri et al. 2018). Fifty-four isolated human lenses were sampled with an 880 nm SLD in a raster scan pattern. Exit ray slopes over a 6 mm pupil were used to determine Zernike wavefront coefficients. Th...

Purpose: To evaluate the differences in intraocular lens (IOL) injectors and to assess the effect of IOL insertion on injector tips and eyes after cataract surgery in a rabbit model. Setting: Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida, USA....

The lens equivalent refractive index (RI) is commonly used in calculations of crystalline lens power. However, accurate determination of the equivalent RI in vivo is challenging due to the need of multiple measurements with different ocular biometry devices. A custom extended-depth Spectral Domain-OCT system was utilized to provide measurements of...

The Ocular Photosensitivity Analyzer (OPA), a new automated instrument to quantify the visual photosensitivity thresholds (VPT) in healthy and light sensitive subjects, is described. The OPA generates light stimuli of varying intensities utilizing unequal ascending and descending steps to yield the VPT. The performance of the OPA was evaluated in h...

Purpose: Quantifying the geometrical changes of the human crystalline lens with age is essential for the design of solutions for age-related disorders such as cataract and presbyopia. We estimated the full shape geometry of the crystalline lens ex vivo and in vivo using optical coherence tomography (OCT) Methods: 3-D OCT images were acquired from i...

We present a new in vitro 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 sens...

Purpose Our purpose was to develop a robotic remotely operated stereo slit lamp system allowing three-dimensional stereo viewing and recording of the patient's examination via local area network, Internet, and satellite. Methods A commercial slit lamp was modified to accept motors and servos to permit control of all optical and mechanical componen...

Purpose : Recent studies suggest that peripheral refraction may be a factor in myopia onset and progression. Age-related changes in lens shape and refractive index gradient due to continuous lens growth with age may produce changes in the peripheral optics of the whole eye. The purpose of this study was to quantify the peripheral defocus of the iso...

Purpose : Quantifying the geometrical changes of the human crystalline lens with age is essential for the design of solutions for age-related disorders such as cataract and presbyopia. We estimated the full shape geometry of the crystalline lens ex vivo and in vivo using optical coherence tomography (OCT). Methods : 3-D OCT images were acquired fr...

Purpose To characterize the peripheral defocus of the monkey crystalline lens and its changes with accommodation. Methods 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...

Purpose To determine the indications, long-term clinical and visual outcomes, and complications of the aphakic snap-on type I Boston keratoprosthesis (KPro). Design Retrospective, non-comparative case series. Methods Forty-five eyes of 43 patients with type I aphakic snap-on KPros with at least 1 year of follow-up were included. The past medical...

Optical coherence tomography (OCT) offers new options for imaging the ciliary muscle allowing direct in vivo 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 exam...

Purpose: Visual photosensitivity is a common symptom difficult to measure and diagnose, and is found in many ocular and neurological disorders. We developed two novel reproducible quantitative assessments of visual photosensitivity. Methods: We designed and built the ocular photosensitivity analyzer (OPA), an automated instrument to determine li...

Purpose: To evaluate the efficacy of rose bengal PDAT for the management of a patient with multidrug-resistant Fusarium keratoplasticum keratitis unresponsive to standard clinical treatment. Methods: This case report presents a clinical case of F. keratoplasticum keratitis not responsive to standard medical care. In vitro studies from patients c...

Purpose: To determine the impact of total pars plana vitrectomies (PPVs) with peripheral shaving of the vitreous base on the rates of postoperative complications in patients with aphakic, snap-on type I Boston keratoprostheses (KPros). Design: Retrospective, consecutive case series. Participants: A total of 48 eyes in 46 patients with implanta...