Variability of manual ciliary muscle segmentation in optical coherence tomography images

© 2018 Optical Society of America. 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 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

Molecular epidemiology and resistance profiles among healthcare- and community-associated Staphylococcus aureus keratitis isolates

Jeffrey C Peterson,1,2 Heather Durkee,1,2 Darlene Miller,3,4 Jorge Maestre-Mesa,3,4 Alejandro Arboleda,1 Mariela C Aguilar,1 Nidhi Relhan,1 Harry W Flynn Jr,3 Guillermo Amescua,3 Jean-Marie Parel,1–3 Eduardo Alfonso3 1Ophthalmic Biophysics Center, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; 2Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA; 3Anne Bates Leach Eye Center, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA; 4Ocular Microbiology Laboratory, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA 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 Staphylococcus aureus keratitis isolates collected over an 11-year period (2006–2016).Results: Two major USA clonal complexes (CC), CC5 (n=30, 40%) and CC8 (n=28, 37.3%), accounted for 77.3% of the collected S. aureus isolates. USA100, traditionally healthcare associated (n=18/47, 38.3%), and USA300, traditionally community associated (n=12/47, 25.5%), were the dominant MRSA strains. Four (22.2%) of the USA100 MRSA isolates were recovered from patients with no prior healthcare exposure. Eleven (91.7%) of the USA300 isolates were recovered from patients with documented healthcare risk factors. MSSA isolates were polyclonal (n=13). Ninety-three percent of MSSA infections were of healthcare origin. Thirty-seven of 61 (60.6%) healthcare- and 11 of 14 (78.6%) community-associated strains were resistant to three or more antibiotic classes. Sixty-eight percent (n=51) of isolates harbored three of more resistance determinants (genes). The Panton-Valentine Leucocidin gene was detected in 11 (14.7%) of the study isolates. The majority (72.7%) of the strains were members of the USA300 MRSA clone.Conclusion: Clonal complexes CC5 and CC8 were the most frequent clones detected among both the MSSA and the MRSA keratitis isolates. USA100 and USA300 clones were the dominant MRSA genotypes. The USA300 MRSA clone has become a leading cause of healthcare-associated keratitis in South Florida. The USA100 MRSA clone has emerged as an increasing cause of community-associated corneal infections in our outpatient population. This shifting epidemiology coupled with the increasing prevalence of multidrug resistance among both MSSA and MRSA keratitis is a cause of concern. Keywords: MRSA, MSSA, DNA microarray, USA100, USA300, clone

System for on-and off-axis volumetric OCT imaging and ray tracing aberrometry of the crystalline lens

© 2018 Optical Society of America. 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 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

Assessment of eye length changes in accommodation using dynamic extended-depth OCT

© 2017 Optical Society of America. 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