A Retroreflection Reduction Technique Based on the Wavefront Coded Imaging System

A novel anti-cat-eye effect imaging technique based on wavefront coding is proposed as a solution to the problem of previous anti-cat-eye effect imaging techniques where imaging quality was sacrificed to reduce the retroreflection from the photoelectric imaging equipment. With the application of the Fresnel–Kirchhoff diffraction theory, and the definition of generalized pupil function combining both phase modulation and defocus factors, the cat-eye echo formation of the wavefront coded imaging system is theoretically modeled. Based on the physical model, the diffracted spot profile distribution and the light intensity distribution on the observation plane are further simulated with the changes in the defocus parameter and the phase modulation coefficient. A verification test on the cat-eye laser echo power of the wavefront coded imaging system and that of the conventional imaging system at a 20 m distance are conducted, respectively. Simulations and experiment results show that compared with conventional imaging systems, the wavefront coding imaging system can reduce the retroreflection echo by two orders of magnitude while maintaining better imaging quality through defocusing.

Optical Aberration Calibration and Correction of Photographic System Based on Wavefront Coding

The image deconvolution technique can recover potential sharp images from blurred images affected by aberrations. Obtaining the point spread function (PSF) of the imaging system accurately is a prerequisite for robust deconvolution. In this paper, a computational imaging method based on wavefront coding is proposed to reconstruct the wavefront aberration of a photographic system. Firstly, a group of images affected by local aberration is obtained by applying wavefront coding on the optical system’s spectral plane. Then, the PSF is recovered accurately by pupil function synthesis, and finally, the aberration-affected images are recovered by image deconvolution. After aberration correction, the image’s coefficient of variation and mean relative deviation are improved by 60% and 30%, respectively, and the image can reach the limit of resolution of the sensor, as proved by the resolution test board. Meanwhile, the method’s robust anti-noise capability is confirmed through simulation experiments. Through the conversion of the complexity of optical design to a post-processing algorithm, this method offers an economical and efficient strategy for obtaining high-resolution and high-quality images using a simple large-field lens.

Pupillotonia and Adie Syndrome

The aim of the work is to approach the examination of the pupil with a focus on anisocoria, its characteristics and approach to the diagnosis of pupillotonia and Adie's syndrome and its clinical evaluation. Pupil function is important not only in neurophthalmological examination but also in general ophthalmological examination. First of all, we need to know how the reflex arc works in order to be able to exclude or confirm whether the parasympathetic or sympathetic is affected. It is also necessary to know the exact characteristics of the pupil, such as size, shape, placement, function and reaction to light and at close range. Only on this basis can we distinguish pathological features. We do not often encounter this diagnosis, but it is necessary to keep it in mind, especially in the field of neurophthalmology but also in general ophthalmology. We also present three cases of pupilotonia and Adie's syndrome, which we diagnosed at the Department of Ophthalmology, Faculty of Medicine, Comenius University, after the patient himself came by emergency admission or was sent directly to ophthalmology clinic. In the discussion, we present various other diagnoses, where the reflex arc may not be affected, but the pathological pupil is caused by intraocular tumors, general systemic diseases and, last but not least, local therapy or alkaloids.

Novel risk factor for fatal arrhythmia in Brugada syndrome

Background Brugada syndrome (BrS) is a genetic disease associated with increased risk of ventricular fibrillation (VF)/ventricular tachycardia (VT). The VF/VT in BrS occurs more frequently during a night time or at a rest with parasympathetic nerve activation. Some risk factors of VF/VT occurrence in BrS have been elucidated, however, it remains controversial about risk stratification. Salusin-β is an endogenous bioactive peptide that systemically exerts rapid and profound hypotensive and bradycardic activities and parasympathomimetic hemodynamic actions in vivo. Previous reports suggested that salusin-β is suppressed following physiological parasympathetic stimulation and appears to constitute a negative feedback relationship with the parasympathetic nervous system. Purpose We hypothesized that salusin-β is associated with the occurrence of VF/VT in BrS. Methods The study population consisted of 26 BrS patients with newly implantation of implantable cardioverter defibrillator (ICD) during 2003–2008. In all patients, salusin-β was measured in supine position after 20 minute rest. The date of salusin-β sampling was set as the registration point for this study. The VF/VT was defined as any episode of fatal ventricular tachyarrhythmia or any appropriate shock. In accordance with the presence or absence of VF/VT events within 5 years, all patients were divided into VF/VT group (n=6) and non-VF/VT group (n=20).Various clinical parameters were compared between the two groups. For analysis of autonomic nervous function, heart rate variability (HRV) and pupil function were evaluated. Results The mean age was 54±17 years old. There is no differences between the two groups in clinical parameters. In analysis of HRV, the high-frequency component (0.15–0.40 Hz; HF), low frequency component (0.04–0.15 Hz; LF) and the LF/HF ratio were analyzed over 24 h. LF/HF ratio was significantly lower over 24h in VF/VT groups in comparison with non-VF/VT groups [day-time; 1.8 (1.2–5.6) vs. 5.2 (3.4–8.8), p=0.048, night-time; 1.2 (1.1–1.3) vs. 3.9 (2.5–8.7), p=0.003]. Furthermore, in analysis of pupil function, right/left miosis ratio was higher in VT/VF groups in comparison with non-VT/VF groups [right pupil; 0.39 (0.37–0.59) vs. 0.34 (0.28–0.38), p=0.035, left pupil; 0.43 (0.36–0.50) vs. 0.33 (0.28–0.40), p=0.049]. In plasma total salusin-β levels, the VF/VT groups exhibited significantly lower than non-VF/VT groups (55.2±14.6 vs. 73.2±22.2, p=0.039, Figure). Conclusions Salusin-β was associated with the occurrence of VF/VT in Brugada syndrome. Salusin-β might be useful to identify high-risk patients for the occurrence of VT/VF events in Brugada syndrome. Funding Acknowledgement Type of funding source: None