Testing Visual Fields in Children

Visual fields in the pediatric population are an essential part of the eye exam that remain challenging to even the most experienced clinicians. Becoming educated in the multiple ways a child's visual field can be tested regardless of age and cognitive and physical abilities will allow the clinician to gain better insight into the child's function and in some cases, allow the clinician to identify pathological or neurological anomalies in the visual pathway. Gross visual field or functional visual field extent can be estimated by tests such as confrontation visual field testing, finger counting field testing, and white sphere kinetic perimetry. For threshold measurements of a child's visual fields, the Goldmann perimeter, or the more advanced computerized tests such as the Humphrey perimeter, Octopus perimeter, or frequency doubling technology perimeter can be used. Modifications can be made to certain tests to better suit the child's cognitive and physical abilities. The chapter covers different methods of visual field testing specific for the pediatric population.

Design and Thermal Analysis of Temperature Control Experiment Box for Final Optic Assembly

The Final Optic Assembly (FOA) is one of the key components of the inertial confinement nuclear fusion device. The temperature change in the FOA is related to the laser frequency conversion efficiency of the frequency doubling crystal. In order to research the temperature control of FOA, this paper considers the internal atmosphere and internal structure of FOA, designed and fabricated a vacuum temperature control experiment box, and set up heat sources inside the box to simulate the internal heating of the FOA. This article uses different radiation heat transfer models to analysis the temperature field of the vacuum experiment box. Compare the thermal simulation results of the S2S model and the DO model, and compare them with the actual temperature of the vacuum experiment box under the same boundary conditions. The results show that the S2S model fits well with the experimental results and is more suitable for thermal analysis of FOA, which is of great significance to the follow-up FOA temperature control research.

Nonlinear Suppression of a Dual-Tube Coriolis Mass Flowmeter Based on Synchronization Effect

Nonlinear interference components exist in the output signals of dual-tube Coriolis mass flowmeters (CMFs) which affect the sensitivity and accuracy of the devices. This nonlinearity still appears under zero flow, which is manifested when the output signal contains a frequency doubling signal. This study (1) investigated an additional-mass method to suppress the nonlinear frequency doubling phenomenon, (2) established a coupling system vibration model with additional mass, built a dynamic differential equation for the vibration of the double-beam coupling system from the Lagrange equation, (3) obtained amplitude frequency information using a fourth-order Runge–Kutta method, (4) determined the suppression effect of the additional mass on the nonlinear frequency doubling phenomenon, and (5) experimentally verified the CMF. The results showed that the base coupled the vibrations of two beams, and the symmetric additional mass suppressed the nonlinear frequency doubling phenomenon, thus suppressing low or high frequencies. Also, the effect of pipeline defects simulated under asymmetric additional mass was obtained through numerical analysis and experimental data. Flowmeters with a required measuring frequency range had the optimal suppression effect on nonlinear frequency doubling and provided theoretical guidance for the nondestructive testing of measuring tubes.

New options for the diagnosis of normal tension glaucoma in the light of Professor V.V. Volkov’s concept of its pathogenesis

PURPOSE:To measure lamina cribrosa thickness (LCT) and lamina cribrosa depth (LCD), optic nerve subarachnoid space width (ONSASW) in patients with normal tension glaucoma and in healthy individuals and to compare these data with the results of our own pilot study. MATERIALS AND METHODS:The 1st group included 13 patients (22 eyes) with normal tension glaucoma aged 39 to 88 years (59.8 10.9 years). The 2nd (control) group included 10 healthy people (20 eyes) aged 40 to 59 years (47.9 5.5 years). All subjects underwent structural and functional assessment of the optic nerve head using optical coherent tomograph (OCT) RTVue-100 (Optovue, USA), Humphrey perimeter (HFA II 745i, Germany-USA), and our own modification of Frequency Doubling Technology perimetry. LCT and LCD were measured by OCT RS-3000 Advance (Nidek, Japan). To measure ONSASW we used a cross-sectional image of the optic nerve taken with Magnetic Resonance Imaging (GE Optima MR450w MRI, USA). RESULTS:Differences in the 1st and 2nd groups between the mean values of LCT (234.14 27.73 and 336.25 21.0 m, respectively;p= 0.0000), LCD (461.8 101.7 and 361.65 58.2 m, respectively;p= 0.0004) and ONSASW (1.371 0.035 and 1.52 0.133 mm, respectively;p= 0.011) were statistically significant. CONCLUSION:Patients with normal tension glaucoma had significantly higher LCD value with significantly lower LCT and ONSASW values compared to healthy individuals, which is comparable with the results of our pilot study, and confirms the importance of these morphometric criteria in normal tension glaucoma diagnosis verification.