Dataset Information

A Rayleigh Scatter-Based Ocular Flare Analysis Meter for Flare Photometry of the Anterior Chamber.

ABSTRACT: PURPOSE:Existing flare photometers are based on the Tyndall effect, which requires sophisticated laser photometry. The ocular flare analysis meter (OFAM) is a nonlaser photometer that uses quantitative Rayleigh scatter and absorption from visible light to compute a flare value. This study is designed to correlate OFAM measurements with qualitative measurements of flare in vitro and in vivo. METHODS:Following validation of the device on artificial anterior chambers containing known protein concentrations, flare readings were obtained from 90 subjects (46 with and 44 without uveitis) in one eye. Subjects were graded by the Standardization of Uveitis Nomenclature (SUN) working group flare scoring system and received the OFAM flare measurements. RESULTS:The OFAM showed linear response in vitro to protein concentrations ranging from 0 to 0.5 mg/ml. In clinical use in subjects ranging from SUN flare scores of 0+ to 2+, OFAM showed statistically significant measurement accuracy (P = 0.0008 of flare 0 versus flare 2; P = 0.031 of flare 0 versus flare 1). Distinction of SUN scores 1 and 2 was borderline significant (P = 0.057). CONCLUSION:The OFAM photometry correlates with the standard SUN scoring system. This method may provide an objective method to diagnosis and monitor uveitis. Further longitudinal studies are warranted. TRANSLATIONAL RELEVANCE:Currently, ocular flare is assessed qualitatively in most clinical settings. The existing methodology uses only Tyndall effect to measure flare. The OFAM uses an alternate, nonlaser means for measurement of anterior chamber flare by measure of Raleigh scatter. This pilot clinical study suggests that the OFAM device may be useful in measurement of uveitis activity.

SUBMITTER: Lam DL

PROVIDER: S-EPMC4678729 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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A Rayleigh Scatter-Based Ocular Flare Analysis Meter for Flare Photometry of the Anterior Chamber.

Lam Deborah L DL Axtelle Jim J Rath Susan S Dyer Andrew A Harrison Benjamin B Rogers Claude C Menon Naresh N Van Gelder Russell N RN

Translational vision science & technology 20151211 6

<h4>Purpose</h4>Existing flare photometers are based on the Tyndall effect, which requires sophisticated laser photometry. The ocular flare analysis meter (OFAM) is a nonlaser photometer that uses quantitative Rayleigh scatter and absorption from visible light to compute a flare value. This study is designed to correlate OFAM measurements with qualitative measurements of flare in vitro and in vivo.<h4>Methods</h4>Following validation of the device on artificial anterior chambers containing known ...[more]

PMID: 26688778

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Project description:PurposeTo investigate the relationship between early post-operative anterior chamber inflammation (aqueous flare) and central corneal thickness (CCT) after cataract surgery and to evaluate the effect of anti-inflammatory prophylaxis on CCT.SettingDepartment of Ophthalmology, Rigshospitalet-Glostrup, University Hospital Copenhagen, Denmark.DesignPost-hoc analysis of a prospective randomized controlled trial.Patients and methodsA total of 470 participants who underwent standard cataract surgery were randomly allocated to prophylactic treatment with nonsteroidal anti-inflammatory drug (NSAID, groups C and D) or a combination of NSAID and steroid eye drops (groups A and B), commenced either pre-operatively (A and C) or post-operatively on the day of surgery (B and D), or "drop-less surgery" (peri-operative subtenon depot of dexamethasone, group E). Aqueous flare was measured before and three days after surgery. CCT was measured before surgery, three days, three weeks, and three months after surgery. Data were analyzed according to the intention-to-treat method.ResultsDoubling of aqueous flare increased mean CCT by 15.6 microns (95% CI 9.8; 21.3, P<0.001) three days after surgery. Mean CCT increased from 549 microns (95% CI 545; 552) at baseline to 594 microns (95% CI 585; 602) three days after surgery and returned to 551 microns (95% CI 545; 557) three months after surgery. Mean CCT was thinner in group C compared to group A three days after surgery. No difference was found for any other groups or time points.ConclusionIncreased anterior chamber inflammation was associated with significant corneal thickening three days after cataract surgery. Choice of anti-inflammatory regimen seemed to be of no or minimal importance on CCT when the effect of inflammation was accounted for. Corneal thickening is possibly mediated by underlying deterioration of the blood-aqueous barrier and corneal endothelium pump function caused by a post-operative inflammatory response.

Project description:PurposeWe sought to investigate anatomic mechanisms of angle narrowing by assessing ocular biometric determinants of anterior chamber angle width.DesignPopulation-based cross-sectional study.MethodsSubjects ≥50 years of age from the Chinese American Eye Study underwent a comprehensive ocular examination, including anterior segment optical coherence tomography imaging and ultrasound A-scan. Independent variables, including anterior chamber depth (ACD), lens vault (LV), iris curvature (IC), anterior chamber width, lens thickness, vitreous cavity depth, and axial length, and dependent variables, including angle opening distance, were measured in 1 randomly selected eye per subject. Univariable and multivariable regression models with standardized regression coefficients (SRCs) and semipartial correlation coefficients squares (SPCC2) were used to assess relative and unique contributions by independent variables to angle width.ResultsTwo thousand two hundred twenty-five subjects (1433 women and 834 men) were included in the analysis. All biometric parameters except lens thickness differed between men and women (age-adjusted P < .001). In model 1A (R2 = 0.66), which included ACD, lens thickness, and vitreous cavity depth, ACD (SRC = 0.64, SPCC2 = 0.19) and IC (SRC = -0.26, SPCC2 = 0.041) were the strongest determinants of angle opening distance. In model 1B (R2 = 0.58), which included LV and axial length, LV (SRC = -0.46, SPCC2 = 0.1) and IC (SRC = -0.3, SPCC2 = 0.047) were the strongest determinants of angle opening distance. Determinants of angle width were similar in separate multivariable models for men and women.ConclusionsACD, LV, and IC are the strongest determinants of angle width in Chinese Americans. Sex-related differences in angle width are explained by differences among biometric measurements. These results provide insights into anatomic mechanisms of angle narrowing and have important implications for quantitative assessments of angle closure eyes.

Dataset Information

A Rayleigh Scatter-Based Ocular Flare Analysis Meter for Flare Photometry of the Anterior Chamber.

Publications

A Rayleigh Scatter-Based Ocular Flare Analysis Meter for Flare Photometry of the Anterior Chamber.

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