Surgical loupe usage among oculoplastic surgeons in North America.

OBJECTIVE: To study the patterns of usage and perception among U.S. oculoplastic surgeons regarding surgical loupes. METHODS: An anonymous 20-question survey was emailed out to the American Society of Ophthalmic Plastic and Reconstructive Surgery listserv. Data were compiled in Google Forms. SPSS was used for statistical analyses. This study was approved by the institutional review board. RESULTS: Of the 609 members contacted, 239 (39%) completed the survey; 95% of respondents owned loupes and 78% regularly used them. No association was observed between frequency of loupe usage and sex or years in practice. The most common magnification and brand were 2.5× and Designs for Vision, respectively. The most common problems associated with loupes were limited vision (33%) and lack of comfort (24%), with 11% citing neck and cervical spinal disorders. The most common benefits were magnification (93%) and increased visual accuracy (68%). Of the respondents, 56% believed improved patient care to be a benefit and 76% believed that loupes enhance surgical outcome. With regard to training, 67% supported incorporating loupes into residency, 35% believed in mandating loupe purchase, and 25% wanted residencies to provide loupes at no cost. Respondent support for the use of loupes in practice and training was directly correlated with how frequently they used loupes. CONCLUSIONS: The vast majority of respondents owned loupes. Although most loupe owners used loupes regularly, a sizable proportion operated with limited vision and lack of comfort. Overall, just over half of respondents believed that loupes improve patient care and should be integrated into residency.

Exact results for Schrödinger cats in driven-dissipative systems and their feedback control.

In quantum optics, photonic Schrödinger cats are superpositions of two coherent states with opposite phases and with a significant number of photons. Recently, these states have been observed in the transient dynamics of driven-dissipative resonators subject to engineered two-photon processes. Here we present an exact analytical solution of the steady-state density matrix for this class of systems, including one-photon losses, which are considered detrimental for the achievement of cat states. We demonstrate that the unique steady state is a statistical mixture of two cat-like states with opposite parity, in spite of significant one-photon losses. The transient dynamics to the steady state depends dramatically on the initial state and can pass through a metastable regime lasting orders of magnitudes longer than the photon lifetime. By considering individual quantum trajectories in photon-counting configuration, we find that the system intermittently jumps between two cats. Finally, we propose and study a feedback protocol based on this behaviour to generate a pure cat-like steady state.

SyntEyes: A Higher-Order Statistical Eye Model for Healthy Eyes.

PURPOSE: Stochastic eye models are a method to generate random biometry data with the variability found in the general population for use in optical calculations. This work improves the accuracy of a previous model by including the higher-order shape parameters of the cornea. METHODS: The right eye biometry of 312 subjects (40.8 ± 11.0 years of age) were measured with an autorefractometer, a Scheimpflug camera, an optical biometer, and a ray tracing aberrometer. The corneal shape parameters, exported as Zernike coefficients, were converted to eigenvectors for dimensional reduction. The remaining 18 parameters were modeled as a sum of two multivariate Gaussians, from which an unlimited number of synthetic data sets (SyntEyes) were generated. After conversion back to Zernike coefficients, the data were introduced into ray tracing software. RESULTS: The mean values of nearly all SyntEyes parameters were statistically equal to those of the original data (two one-sided t-test, P > 0.05/109, Bonferroni correction). The variability of the SyntEyes parameters was similar to the original data for most important shape parameters and intraocular distances (F-test, P < 0.05/109), but significantly lower for the higher-order shape parameters (F-test, P > 0.05/109). The same was seen for the correlations between higher-order shape parameters. After applying simulated cataract or refractive surgery to the SyntEyes model, a very close resemblance to previously published clinical outcome data was seen. CONCLUSIONS: The SyntEyes model produces synthetic biometry that closely resembles clinically measured data, including the normal biological variations in the general population.

Biophotonic Modelling of Cardiac Optical Imaging.

Computational models have been recently applied to simulate and better understand the nature of fluorescent photon scattering and optical signal distortion during cardiac optical imaging. The goal of such models is both to provide a useful post-processing tool to facilitate a more accurate and faithful comparison between computational simulations of electrical activity and experiments, as well as providing essential insight into the mechanisms underlying this distortion, suggesting ways in which it may be controlled or indeed utilised to maximise the information derived from the recorded fluorescent signal. Here, we present different modelling methodologies developed and used in the field to simulate both the explicit processes involved in optical signal synthesis and the resulting consequences of the effects of photon scattering within the myocardium upon the optically-detected signal. We focus our attentions to two main types of modelling approaches used to simulate light transport in cardiac tissue, specifically continuous (reaction-diffusion) and discrete stochastic (Monte Carlo) methods. For each method, we provide both a summary of the necessary methodological details of such models, in addition to brief reviews of relevant application studies which have sought to apply these methods to elucidate important information regarding experimentally-recorded optical signals under different circumstances.

Optical analysis of lithium carbonate: towards the development of a portable lithium blood level analyzer for bipolar disorder patients.

Lithium medication is the gold standard of treatment in Bipolar Disorder patients, preventing and reducing mood swings and suicidality. However, despite its effectiveness, it is a potentially hazardous drug requiring regular monitoring of blood levels to ensure toxic levels are not reached. This paper describes the first steps towards developing a new portable device that can be used by Bipolar Disorder patients to facilitate the analysis of lithium blood levels at home. Solutions of lithium carbonate have been optically fingerprinted using a high-end spectrophotometer. Preliminary measurements indicate that while the visible to near infrared region of the absorption spectra fall heavily within the water band, measurements in the Ultraviolet region show a strong distinction between different lithium concentrations. The optical spectra of Lithium in the 220 nm to 230 nm region demonstrated the ability to differentiate between concentrations representing those found in patients.

Statistical eye model for normal eyes.

PURPOSE: To create a binocular statistical eye model based on previously measured ocular biometric data. METHODS: Thirty-nine parameters were determined for a group of 127 healthy subjects (37 male, 90 female; 96.8% Caucasian) with an average age of 39.9 ± 12.2 years and spherical equivalent refraction of -0.98 ± 1.77 D. These parameters described the biometry of both eyes and the subjects' age. Missing parameters were complemented by data from a previously published study. After confirmation of the Gaussian shape of their distributions, these parameters were used to calculate their mean and covariance matrices. These matrices were then used to calculate a multivariate Gaussian distribution. From this, an amount of random biometric data could be generated, which were then randomly selected to create a realistic population of random eyes. RESULTS: All parameters had Gaussian distributions, with the exception of the parameters that describe total refraction (i.e., three parameters per eye). After these non-Gaussian parameters were omitted from the model, the generated data were found to be statistically indistinguishable from the original data for the remaining 33 parameters (TOST [two one-sided t tests]; P < 0.01). Parameters derived from the generated data were also significantly indistinguishable from those calculated with the original data (P > 0.05). The only exception to this was the lens refractive index, for which the generated data had a significantly larger SD. CONCLUSIONS: A statistical eye model can describe the biometric variations found in a population and is a useful addition to the classic eye models.