Significance: Code verification is an unavoidable step prior to using a Monte Carlo (MC) code. Indeed, in biomedical optics, a widespread verification procedure for MC codes is still missing. Analytical benchmarks that can be easily used for the verification of different MC routines offer an important resource. Aim: We aim to provide a two-step verification procedure for MC codes enabling the two main tasks of an MC simulator: (1) the generation of photons’ trajectories and (2) the intersections of trajectories with boundaries separating the regions with different optical properties. The proposed method is purely based on elementary analytical benchmarks, therefore, the correctness of an MC code can be assessed with a one-sample t-test. Approach: The two-step verification is based on the following two analytical benchmarks: (1) the exact analytical formulas for the statistical moments of the spatial coordinates where the scattering events occur in an infinite medium and (2) the exact invariant solutions of the radiative transfer equation for radiance, fluence rate, and mean path length in media subjected to a Lambertian illumination. Results: We carried out a wide set of comparisons between MC results and the two analytical benchmarks for a wide range of optical properties (from non-scattering to highly scattering media, with different types of scattering functions) in an infinite non-absorbing medium (step 1) and in a non-absorbing slab (step 2). The deviations between MC results and exact analytical values are usually within two standard errors (i.e., t-tests not rejected at a 5% level of significance). The comparisons show that the accuracy of the verification increases with the number of simulated trajectories so that, in principle, an arbitrary accuracy can be obtained. Conclusions: Given the simplicity of the verification method proposed, we envision that it can be widely used in the field of biomedical optics.

The research in optical sensors has been largely encouraged by the demand for low-cost and less or non-invasive new detection strategies. The invention of the random laser has opened a new frontier in optics, providing also the opportunity to explore new possibilities in the field of sensing, besides several different and peculiar phenomena. The main advantage in exploiting the physical principle of the random laser in optical sensors is due to the presence of the stimulated emission mechanism, which allows amplification and spectral modification of the signal. Here, we present a step forward in the exploitation of this optical phenomenon by a revisitation of a previous experimental setup, as well as the measurement method, in particular to mitigate the instability of the results due to shot-to-shot pump energy fluctuations. In particular, the main novelties of the setup are the use of optical fibers, a reference sensor, and a peristaltic pump. These improvements are devoted to: eliminating optical beam alignment issues; improving portability; mitigating the variation in pump energy and gain medium performances over time; realizing an easy and rapid change of the sensed medium. The results showed that such a setup can be considered a prototype for a portable device for directly measuring the scattering of liquid samples, without resorting to complicated numerical or analytic inversion procedures of the measured data, once the suitable calibration of the system is performed.

Purpose: A novel enhanced monofocal intraocular lens (IOL) has been developed to improve functional intermediate vision, maintaining a distance vision comparable to a standard monofocal lens and avoiding the drawbacks of multifocal IOLs. The aim of this study is to perform optical bench analysis and to evaluate refractive and visual outcomes and patient satisfaction. Methods: This prospective comparative single-center study was conducted in Careggi Hospital, University of Florence (Italy). We included 100 eyes from 50 patients who underwent bilateral cataract surgery. One group received the standard monofocal Tecnis GCB00 IOL, while the other group received the novel enhanced monofocal Evolux IOL. We evaluated binocular visual and refractive outcomes at 6 months after surgery. Binocular defocus curves and contrast sensitivity (CS) were also assessed. Optical quality was also analyzed in terms of higher-order aberrations (HOAs), modulation transfer function (MTF), objective scatter index (OSI), Strehl ratio, effective lens position (ELP), and halo analysis. A Patient-Reported Spectacle Independence Questionnaire (PRSIQ) was performed to assess spectacle independence outcomes. Finally, we analyzed the optical bench of both lenses. Results: All eyes implanted with Evolux achieved excellent distance vision, comparable to that achieved with GCB00. Evolux showed better intermediate and near vision, without any loss of visual quality, contrast sensitivity, or the presence of halos and photic phenomena. The optical bench analysis confirmed the different optical properties of the two lenses and supported the behavior obtained with the clinical defocus curve. Conclusions: These preliminary results show good refractive accuracy and visual outcomes for the enhanced monofocal IOL Evolux after cataract surgery. Further studies are needed to confirm our findings in terms of the number of patients and the period of follow-up.

Purpose: A novel enhanced monofocal intraocular lens (IOL) has been developed to improve functional intermediate vision, maintaining a distance vision comparable to a standard monofocal lens and avoiding the drawbacks of multifocal IOLs. The aim of this study is to perform optical bench analysis and to evaluate refractive and visual outcomes and patient satisfaction. Methods: This prospective comparative single-center study was conducted in Careggi Hospital, University of Florence (Italy). We included 100 eyes from 50 patients, that underwent bilateral cataract surgery. One group was implanted with the standard monofocal IOL Tecnis GCB00 and the other group the novel enhanced monofocal lens Evolux. We evaluated monocular and binocular visual and refractive outcomes at 6 months after surgery. Binocular defocus curves and contrast sensitivity (CS) were also assessed. Optical quality was also analyzed, in terms of higher-order aberrations (HOAs), Modulation Transfer Function (MTF), Objective Scatter Index (OSI), Strehl-ratio, Effective Lens Position (ELP) and halo analysis. A Patient-Reported Spectacle Independence Questionnaire (PRSIQ) was performed to evaluate spectacle independence outcomes. Finally, we analyzed the optical bench of both lenses. Results: All eyes implanted with Evolux achieved excellent distance vision, comparable to those achieved with GCB00. Evolux showed better intermediate and near vision, without any loss of visual quality, contrast sensitivity, or the presence of halos and photic phenomena. The optical bench analysis confirmed the different optical properties of the two lenses and supported the behavior obtained with clinical defocus curve Conclusion: These preliminary results show good refractive accuracy and visual outcomes for the enhanced monofocal IOL Evolux after cataract surgery. Further studies need to confirm our findings in terms of number of patients and period of follow-up.