Mydriasis-Free Flicker Electroretinograms in 204 Healthy Children Aged 0-18 Years: Reference Data From Two Cohorts

Paediatric norms for photopic electroretinogram testing based on a large cohort of Chinese preschool children

OBJECTIVE

Full-field electroretinogram (ffERG) is an objective test to determine the electroretinal activities in response to light stimulation for investigating retinal physiology and diagnosing retinal diseases. This study aimed to establish a reference data set of photopic electroretinogram (ERG) of Chinese preschool children in Hong Kong to facilitate clinical and research studies.

METHODS AND ANALYSIS

Preschool children aged 3-7 years with normal vision were recruited from local kindergartens. Eye examinations, including cycloplegic spherical equivalent refraction (SER), axial length (AL) and keratometry (K) measurements, were performed. ffERGs of the International Society for Clinical Electrophysiology of Vision (ISCEV) standard photopic flash and 30-Hz flicker protocols were measured using RETeval with Sensor Strip skin electrodes. ERG waveform characteristics were extracted, and relationships between ERG, age, SER, AL and K were evaluated.

RESULTS

A total of 479 children completed the measurements (mean age: 5.0±0.9 years, 45.5% female). Mean, 95% CIs, 5th-95th percentile range of the ERG parameters were reported. Age was positively associated with amplitudes of b-wave and 30-Hz flicker (p<0.01), but negatively associated with implicit times of b-wave and 30-Hz flicker (p<0.01). AL was significantly associated with all amplitudes of a-wave, b-wave and 30-Hz flicker (p≤0.01) and implicit time of both a-wave and 30-Hz flicker (p<0.05). K was positively associated only with 30-Hz flicker amplitude (p=0.01), and no association between all responses and SER.

CONCLUSION

Reference data set of photopic ERG of Chinese preschool children was established. Cross-sectional investigations revealed associations between ERG, age, SER and AL, which were speculated to further implicate the role of retina in refractive error development.

The Development of Electroretinographic Oscillatory Potentials in Healthy Young Children

PURPOSE

This study aimed to summarize the electroretinographic oscillatory potential (OP) responses in healthy young children recorded by RETeval.

METHODS

By using the RETeval system, we recorded the implicit times and amplitudes of the OPs (OP1-5), in 132 healthy children aged from 0 to 11 years old. The age, gender, and data of implicit time and amplitude of each child were recorded and analyzed. Correlation analysis was performed between age and implicit time/amplitude.

RESULTS

No correlation was shown between the implicit times and amplitudes with gender. The implicit times and amplitudes of OP1-5 matured over 10 years of age, with exponential time constants of 1.9, 2.2, 1.8, 1.7, and 1.6 years and 2.1, 2.9, 2.8, 3.0, and 3.2 years, respectively. The majority of the trend occurred within the first 4.6 years.

CONCLUSIONS

In order to diagnose and evaluate vision-related disorders, the OP response is commonly used. The percentiles and age dependence of OP responses calculated and shown in this study could be regarded as reference data in age-matched pediatric patients.

Mechanical Performance Analysis of Steel Beam-Column Joints in Fabricated Multirise Steel Structures after Fire

This study aims to analyze the mechanical properties of fabricated multistory and high-rise steel structures and steel beam-column joints after fire. Considering that the steel structure building has the characteristics of good seismic resistance, flexible structural layout, short construction period, and good safety, first, the thermal and mechanical properties of steel are analyzed. They are thermal conductivity, the thermal expansion coefficient of steel, yield strength, and elastic modulus of ordinary steel. Next, the thermal conduction principle of steel under fire environment is analyzed, including thermal conduction, thermal convection, and thermal radiation. Then, the three-story and three-span reinforced concrete is selected as the experimental object. The local frame calculation model is established through the finite element software Abaqus. It is found that when the axial compression ratio is 1.0 and the fire time of the steel body is 180 min, the vertical deformation speed of the middle column and side column of the frame will increase rapidly. Besides, the bending moment at the bottom of the side column of the frame will increase inversely. The change is not obvious when the axial compression ratio is other values. The axial deformation of the universal beam is obvious under the condition of different fire load ratios. When the load ratio increases, the maximum fire resistance of the universal beam will decrease rapidly. Meanwhile, when the steel body is subjected to the same load ratio, different bearing capacity β has little effect on the fire resistance limit of the steel body. This thesis focuses on a series of changes in the steel of fabricated multistory and high-rise steel buildings after the fire, hoping to provide a reference for the relevant teams of steel construction and make the future housing construction safer.