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Abelson, Mark

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Abelson

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Abelson, Mark
Author's Publications: search.filters.isAuthorOfPublication.3a09e392-5982-4fab-a457-8ff77ed96586

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Now showing 1 - 9 of 9
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    Blink patterns and lid-contact times in dry-eye and normal subjects
    (Dove Medical Press, 2014) Ousler, George W; Abelson, Mark; Johnston, Patrick R; Rodriguez, John; Lane, Keith; Smith, Lisa M
    Purpose To classify blinks in dry eye and normal subjects into six subtypes, and to define the blink rate and duration within each type of blink, as well as the total lid-contact time/minute. Materials and methods This was a single-centered, prospective, double-blind study of eleven dry-eye and ten normal subjects. Predefined subjects watched a video while blinks were recorded for 10 minutes. Partial blinks were classified by percentage closure of maximal palpebral fissure opening: 25%, 50%, 75%. Complete blinks were characterized as full (>0 seconds), extended (>0.1 seconds), or superextended (>0.5 seconds). The mean duration of each type of blink was determined and standardized per minute as total lid-contact time. Results: Total blinks observed were 4,990 (1,414 normal, 3,756 dry eye): 1,809 (50.59%) partial and 1,767 (49.41%) complete blinks among dry-eye subjects versus 741 (52.90%) partial and 673 (47.60%) complete blinks among normal subjects. Only superextended blinks of ≥0.5-second duration were significantly more frequent in dry-eye subjects than normals (2.3% versus 0.2%, respectively; P=0.023). Total contact time was seven times higher in dry-eye subjects than normals (0.565 versus 0.080 seconds, respectively; P<0.001). Isolating only extended blinks (>0.1 second), the average contact time (seconds) was four times longer in dry-eye versus normal subjects (2.459 in dry eye, 0.575 in normals; P=0.003). Isolating only superextended blinks (>0.5 seconds), average contact time was also significantly different (7.134 in dry eye, 1.589 in normals; P<0.001). The contact rate for all full closures was 6.4 times longer in dry-eye (0.045 versus 0.007, P<0.001) than normal subjects. Conclusion: Dry-eye subjects spent 4.5% of a minute with their eyes closed, while normal subjects spent 0.7% of a minute with their eyes closed. Contact time might play a role in the visual function decay associated with increased blink rates.
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    Automated grading system for evaluation of ocular redness associated with dry eye
    (Dove Medical Press, 2013) Rodriguez, John D; Johnston, Patrick R; Ousler, George W; Smith, Lisa M; Abelson, Mark
    Background: We have observed that dry eye redness is characterized by a prominence of fine horizontal conjunctival vessels in the exposed ocular surface of the interpalpebral fissure, and have incorporated this feature into the grading of redness in clinical studies of dry eye. Aim To develop an automated method of grading dry eye-associated ocular redness in order to expand on the clinical grading system currently used. Methods: Ninety nine images from 26 dry eye subjects were evaluated by five graders using a 0–4 (in 0.5 increments) dry eye redness (Ora Calibra™ Dry Eye Redness Scale [OCDER]) scale. For the automated method, the Opencv computer vision library was used to develop software for calculating redness and horizontal conjunctival vessels (noted as “horizontality”). From original photograph, the region of interest (ROI) was selected manually using the open source ImageJ software. Total average redness intensity (Com-Red) was calculated as a single channel 8-bit image as R – 0.83G – 0.17B, where R, G and B were the respective intensities of the red, green and blue channels. The location of vessels was detected by normalizing the blue channel and selecting pixels with an intensity of less than 97% of the mean. The horizontal component (Com-Hor) was calculated by the first order Sobel derivative in the vertical direction and the score was calculated as the average blue channel image intensity of this vertical derivative. Pearson correlation coefficients, accuracy and concordance correlation coefficients (CCC) were calculated after regression and standardized regression of the dataset. Results: The agreement (both Pearson’s and CCC) among investigators using the OCDER scale was 0.67, while the agreement of investigator to computer was 0.76. A multiple regression using both redness and horizontality improved the agreement CCC from 0.66 and 0.69 to 0.76, demonstrating the contribution of vessel geometry to the overall grade. Computer analysis of a given image has 100% repeatability and zero variability from session to session. Conclusion: This objective means of grading ocular redness in a unified fashion has potential significance as a new clinical endpoint. In comparisons between computer and investigator, computer grading proved to be more reliable than another investigator using the OCDER scale. The best fitting model based on the present sample, and usable for future studies, was C4=−12.24+2.12C2HOR+0.88C2RED:C4 is the predicted investigator grade, and C2HOR and C2RED are logarithmic transformations of the computer calculated parameters COM-Hor and COM-Red. Considering the superior repeatability, computer automated grading might be preferable to investigator grading in multicentered dry eye studies in which the subtle differences in redness incurred by treatment have been historically difficult to define.
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    Technical and clinical validation of an environmental exposure unit for ragweed
    (Dove Medical Press, 2016) Gomes, Paul J; Lane, Keith J; Angjeli, Endri; Stein, Linda; Abelson, Mark
    Background: Allergic rhinitis is a common condition, with ragweed pollen one of the more prevalent aeroallergens. Environmental exposure units such as the Allergen BioCube® are valuable models for clinical allergy studies. A study was conducted to validate the Allergen BioCube for uniform ragweed pollen concentrations and clinically relevant sign and symptom responses to ragweed exposure. Methods: Ragweed pollen concentrations were measured on 3 consecutive days in the Allergen BioCube and verified by Rotorod collection and continuous laser particle count measurements. Subjects (N=10) were exposed to ragweed pollen in the BioCube for 3 hours per day for 3 consecutive days. Subjects assessed their nasal itching, sneezing, rhinorrhea, and nasal congestion during each BioCube exposure; total nasal symptom score was computed. Peak nasal inspiratory flow was also assessed during BioCube exposure. Results: Uniform ragweed pollen concentrations were obtained throughout each of the 3-hour testing periods in the Allergen BioCube, both spatially and temporally, at all subject positions, with a low mean standard deviation of 10%. Pronounced increases in mean total nasal symptom scores (6.7±0.94 to 7.6±0.86, last 90 minutes of exposure) occurred for all three BioCube ragweed pollen exposure visits. Mean peak nasal inspiratory flow decreased 24% at 3 hours of BioCube exposure on Day 3. No safety issues of concern occurred in this study. Conclusion: The Allergen BioCube achieved technical and clinical validation for ragweed allergen. Ragweed pollen concentration was uniform both temporally and spatially. Allergic rhinitis signs and symptoms were induced in subjects during exposure to ragweed in the BioCube at clinically meaningful levels for allergy studies.
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    Technical and clinical validation of the Allergen BioCube® for timothy grass
    (John Wiley and Sons Inc., 2017) Angjeli, Endri; Gomes, Paul; Lane, Keith J.; Stein, Linda; Abelson, Mark
    Abstract Introduction: Field studies for allergic rhinitis (AR) commonly have inconsistent allergen concentrations and subject exposure patterns due to varying environmental conditions and subject behaviors. A technical and clinical validation study was conducted for the Allergen BioCube® using timothy grass to confirm uniform allergen concentration and clinically relevant subject symptom responses. Methods: Allergen concentrations were verified by laser particle counts. Subjects (N = 14) with positive skin test reactions and no symptoms at screening received four 3‐h timothy grass exposures in the BioCube over consecutive days. Subjects evaluated nasal itching, sneezing, rhinorrhea, and nasal congestion while in the BioCube; Total Nasal Symptom Score (TNSS) was computed. Peak Nasal Inspiratory Flow (PNIF), Peak Expiratory Flow Rate (PEFR), sIgE blood tests, and Nasal Inflammation Score (NIS) were assessed. A correlation analysis was conducted for mean sIgE, skin test, and TNSS. Results: Uniform timothy grass concentrations were achieved in the BioCube, both spatially and temporally, at all subject positions. Mean TNSS increased substantially from pre‐exposure levels (0.36 ± 0.74 to 1.86 ± 2.14) to maximums of 7.07 ± 2.76 at 1.5 h and 6.71 ± 2.70 at 3 h BioCube exposure. Twelve (86%) subjects had TNSS increases ≥6 units. PNIF decreased 12–24% from baseline at 3‐h BioCube exposure. NIS increased (baseline = 0) to 3.7 (maximum score = 4). A low/moderate correlation (r = 0.485) occurred between mean sIgE blood levels and mean skin tests; neither sIgE or skin tests correlated with mean TNSS. However, subjects with high skin test scores or positive blood IgE tended to also have higher TNSS. Conclusions: The Allergen BioCube achieved technical and clinical validation for uniform timothy grass concentration and clinically meaningful AR sign and symptom responses. The Allergen BioCube can be used to assess the efficacy of therapies for reduction of AR signs and symptoms resulting from grass exposure.
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    The Interblink Interval in Normal and Dry Eye Subjects
    (Dove Medical Press, 2013) Johnston, Patrick R; Rodriguez, John; Lane, Keith J; Ousler, George; Abelson, Mark
    Purpose: Our aim was to extend the concept of blink patterns from average interblink interval (IBI) to other aspects of the distribution of IBI. We hypothesized that this more comprehensive approach would better discriminate between normal and dry eye subjects. Methods: Blinks were captured over 10 minutes for ten normal and ten dry eye subjects while viewing a standardized televised documentary. Fifty-five blinks were analyzed for each of the 20 subjects. Means, standard deviations, and autocorrelation coefficients were calculated utilizing a single random effects model fit to all data points and a diagnostic model was subsequently fit to predict probability of a subject having dry eye based on these parameters. Results: Mean IBI was 5.97 seconds for normal versus 2.56 seconds for dry eye subjects (ratio: 2.33, P = 0.004). IBI variability was 1.56 times higher in normal subjects (P < 0.001), and the autocorrelation was 1.79 times higher in normal subjects (P = 0.044). With regard to the diagnostic power of these measures, mean IBI was the best dry eye versus normal classifier using receiver operating characteristics (0.85 area under curve (AUC)), followed by the standard deviation (0.75 AUC), and lastly, the autocorrelation (0.63 AUC). All three predictors combined had an AUC of 0.89. Based on this analysis, cutoffs of ≤3.05 seconds for median IBI, and ≤0.73 for the coefficient of variation were chosen to classify dry eye subjects. Conclusion: (1) IBI was significantly shorter for dry eye patients performing a visual task compared to normals; (2) there was a greater variability of interblink intervals in normal subjects; and (3) these parameters were useful as diagnostic predictors of dry eye disease. The results of this pilot study merit investigation of IBI parameters on a larger scale study in subjects with dry eye and other ocular surface disorders.
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    Investigation of extended blinks and interblink intervals in subjects with and without dry eye
    (Dove Medical Press, 2013) Rodriguez, John D; Ousler, George W; Johnston, Patrick R; Lane, Keith; Abelson, Mark
    Background: The purpose of this study was to investigate the occurrence and duration of extended blinks ≥ 70 msec and their associated interblink intervals in normal subjects and in subjects with mild to moderate dry eye. Methods: This single-center, prospective, double-blind study included 11 subjects with dry eye and eight subjects with normal eyes. Extended blinks were defined as lid closure in at least two successive video frames (≥70 msec). Digital video imaging of each subject’s eyes was recorded while the subject viewed a 10-minute documentary. The subjects did not know that blink was the outcome being measured. Following capture, the videos were manually analyzed in a masked fashion for the occurrence of extended blinks. The length of the interblink interval (ie, time between blinks) before and after these extended blinks (the interblink interval ratio) was calculated, as well as differences in lid contact times. Results: The dry eye group had a median extended blink duration which was 2.53 times longer than that of the normal group. For subjects with dry eye, interblink intervals post-extended blink were significantly longer than interblink intervals pre-extended blink (P < 0.001). Interblink intervals did not lengthen significantly in normal subjects. In both groups, the duration of the extended blink was significantly (P = 0.001) and positively correlated with interblink interval ratio (post-extended to pre-extended blink interblink interval), such that for each doubling of extended blink duration, the interblink interval ratio increased by 10%. Blinks longer than one second in duration occurred almost exclusively in subjects with dry eye. Conclusion: This study reports three central findings: blink duration tended to be longer in subjects with dry eye; a lengthening of the interblink interval after an extended blink occurred in subjects with dry eye but not in those without dry eye; and a longer blink duration was associated with a significantly increased interblink interval ratio in all subjects.
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    Exacerbation of signs and symptoms of allergic conjunctivitis by a controlled adverse environment challenge in subjects with a history of dry eye and ocular allergy
    (Dove Medical Press, 2013) Gomes, Paulo J; Ousler, George W; Welch, Donna L; Smith, Lisa M; Coderre, Jeffrey; Abelson, Mark
    Background: The goal of this study was to assess the effect of a controlled adverse environment (CAE) challenge on subjects with both allergic conjunctivitis and dry eye. Methods: Thirty-three subjects were screened and 17 completed this institutional review board-approved study. Subjects underwent baseline ocular assessments and conjunctival allergen challenge (CAC) on days 0 and 3. Those who met the ocular redness and itching criteria were randomized to receive either the controlled adverse environment (CAE) challenge (group A, n = 9) or no challenge (group B, n = 8) at day 6. Thirty minutes after CAE/no-CAE, subjects were challenged with allergen and their signs and symptoms graded. Exploratory confocal microscopy was carried out in a subset of subjects at hourly intervals for 5 hours post-CAC on days 3 and 6. Results: Seven minutes post-CAC, subjects exposed to the CAE had significantly greater itching (difference between groups, 0.55 ± 0.25, P = 0.028), conjunctival redness (0.59 ± 0.19, P = 0.002), episcleral redness (0.56 ± 0.19, P = 0.003) and mean overall redness (mean of conjunctival, episcleral, and ciliary redness, 0.59 ± 0.14, P < 0.001). The mean score at 7, 15, and 20 minutes post-CAC for conjunctival redness (0.43 ± 0.17, P = 0.012), episcleral redness (0.49 ± 0.15, P = 0.001), mean overall redness in all regions (0.43 ± 0.15, P = 0.005), and mean chemosis (0.20 ± 0.08, P = 0.017) were also all significantly greater in CAE-treated subjects. Confocal microscopic images of conjunctival vessels after CAC showed more inflammation in CAE-treated subjects. Conclusion: In subjects with both dry eye and allergic conjunctivitis, exposure to adverse environmental conditions causes an ocular surface perturbation that can intensify allergic reactions.
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    A Randomized Trial Assessing the Clinical Efficacy and Microbial Eradication of 1% Azithromycin Ophthalmic Solution vs Tobramycin in Adult and Pediatric Subjects with Bacterial Conjunctivitis
    (Dove Medical Press, 2007) Abelson, Mark; Protzko, Eugene; Shapiro, Aron; Garces-Soldana, Ana; Bowman, Lyle
    Objective: The study was designed to evaluate the efficacy of an ophthalmic formulation of 1% azithromycin in DuraSite® (AzaSite™, InSite Vision, Alameda CA, USA) and demonstrate equivalence with 0.3% tobramycin ophthalmic solution, USP, for the treatment of bacterial conjunctivitis as defined by the resolution of clinical signs and the eradication of pathogens. Design: Prospective, randomized, active-controlled, double-masked, phase 3 trial conducted at 47 US sites between 6 August 2004 and 6 October 2005. Participants: Subjects aged 1 year or older with diagnosis of acute bacterial conjunctivitis. Methods: Bacteriologically confirmed participants received either 1% azithromycin in Dura-Site (n = 159) or tobramycin (n = 157). Masked study medications were dosed 4 times a day for 5 days. Participants in the 1% azithromycin in DuraSite group were dosed twice a day with active drug on days 1 and 2 and once daily on days 3 through 5. The other doses were vehicle. Clinical signs and bacterial cultures were evaluated at visit 3 (day 6 + 1). Results: Clinical resolution was observed in 79.9% of participants in the 1% azithromycin in DuraSite group, as compared with 78.3% of those in the tobramycin group (95% CI: −7.4–10.5). Bacterial eradication was 88.1% in the 1% azithromycin in DuraSite group vs 94.3% in the tobramycin group (95% CI: −12.4–0.0). Analyses of resistance confirmed that 1% azithromycin in DuraSite eradicated Staphylococci and Streptococci strains that are commonly resistant to azithromycin, erythromycin, and fluoroquinolones. Conclusions: The efficacy of 1% azithromycin in DuraSite and tobramycin are equivalent; however, this formulation of azithromycin also permits effective dosing intervals of twice a day on days 1 and 2 followed by once daily on the last 3 days of therapy, for a total of 65% fewer doses. In vitro, the killing spectrum of 1% azithromycin in DuraSite appears to be enhanced relative to 1% azithromycin without DuraSite.
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    Use of the Controlled Adverse Environment (CAE) in Clinical Research: A Review
    (Springer Healthcare, 2017) Ousler, George W.; Rimmer, David; Smith, Lisa M.; Abelson, Mark
    The many internal and external factors that contribute to the pathophysiology of dry eye disease (DED) create a difficult milieu for its study and complicate its clinical diagnosis and treatment. The controlled adverse environment (CAE®) model has been developed to minimize the variability that arises from exogenous factors and to exacerbate the signs and symptoms of DED by stressing the ocular surface in a safe, standardized, controlled, and reproducible manner. By integrating sensitive, specific, and clinically relevant endpoints, the CAE has proven to be a unique and adaptable model for both identifying study-specific patient populations with modifiable signs and symptoms, and for tailoring the evaluation of interventions in clinical research studies.