Biomedical subjects

Fengrong Li

Publications and source records attributed to Fengrong Li.

4 recordsLinked to original sources

PubMed2004

Accuracy of noncycloplegic autorefraction in school-age children in China.

PURPOSE: To evaluate the accuracy of noncycloplegic autorefraction in a representative sample of school-age children in China. METHODS: Refractive error was measured with an autorefractor, both before and after cycloplegia induced with cyclopentolate, in a population-based sample of 4973 children between the ages of 7 and 18 years. Spherical equivalent refractive error and astigmatism as represented by Jackson crossed-cylinders (J0 and J45) were the main outcome measures. RESULTS: Noncycloplegic measurements of equivalent spheres were consistently more negative or less positive than those after cycloplegia, with mean +/- SD differences of -1.23 +/- 0.97 D. The differences were particularly large for hyperopic eyes (mean difference of -2.98 +/- 1.65 D for hyperopia of at least +2.00 D) while becoming progressively smaller for emmetropic eyes, and smaller yet for myopic eyes (mean difference of -0.41 +/- 0.46 D for myopia of -2.00 D or more). Increasing age was associated with increased, but clinically insignificant, differences. Little difference was found between noncycloplegic and cycloplegic measurements of astigmatism: mean J0 and J45 differences were -0.08 +/- 0.13 D and -0.01 +/- 0.09 D, respectively. CONCLUSIONS: Noncycloplegic autorefraction was found to be highly inaccurate in school-age children and, thus, not suitable for studies of refractive error or for prescription of glasses in this population.

Adolescent↗

PubMed2003

[Study on distortion product otoacoustic emissions and expanded high frequency audiometry in noise exposure workers].

OBJECTIVE: To analyse the relationship of distortion product otoacoustic emissions(DPOAE), conventional pure tone audiometry and expanded high frequency audiometry, and discuss the originated mechanism of DPOAE and value in early diagnosis and detection noise-induced deafness. METHOD: DPOAE, conventional pure tone audiometry and expanded high frequency audiometry were performed in 42 young adults with normal hearing of control group and 20 noise exposure workers of test group. DPOAE amplitudes, conventional pure tone hearing thresholds and expanded high frequency hearing thresholds were compared. RESULT: In noise exposure workers against young adults with normal hearing, the pure tone hearing thresholds at 6.0 kHz and expanded high frequency area declined significantly(P < 0.05), DPOAE amplitudes at frequency from 4.0 to 6.0 kHz and 11.2 kHz declined significantly too(P < 0.05), but there existed no significantly difference at frequency from 12.5 to 16.0 kHz between the two groups(P > 0.05). CONCLUSION: DPOAE is potential implement to early diagnose and detect noise-induced deafness. It seems likely that the origination of DPOAE not limited to the outer hair cell in corresponding cochlear area. The originated area and mechanism of DPOAE should be solved by further studies.

Adolescent↗

PubMed2002

The progression of refractive error in school-age children: Shunyi district, China.

PURPOSE: To assess the progression of refractive error and the incidence of myopia in school-age children in the Shunyi District of Beijing, China. DESIGN: A longitudinal cohort study. METHODS: A population-based sample of 4,662 children initially examined in 1998 at ages 5 to 13 years was reexamined between September and November, 2000. Refractive error was measured under cycloplegia with autorefraction. Age, sex, and baseline refractive error were evaluated as risk factors for progression. RESULTS: In 28.5 months, the average change in refractive error was -0.42 diopters (standard deviation, 0.68) in right eyes. Myopic shift of refractive error was associated with female sex, older age, and higher myopic or hyperopic refractive error at baseline. The average change in astigmatic error was essentially zero, with significant change in both directions more likely among those with higher baseline astigmatism. Findings were similar for left eyes. The cumulative incidence of myopia, defined as a spherical equivalent refractive error of -0.50 diopters or more in either eye, among initial emmetropes and hyperopes was 14.1% (95% confidence interval [CI], 11.8%-16.5%) for male and 23.5% (95% CI, 20.8%-26.1%) for female subjects. Myopia incidence increased sixfold to sevenfold between baseline age 5 and 12, before decreasing at age 13, for both male and female subjects. CONCLUSIONS: In the design of cost-effective programs for the periodic screening and treatment of uncorrected refractive error, children initially found to require refractive correction should be targeted for relatively frequent rescreening, as should girls and older children. Further study is required to better understand environmental and genetic risk factors for myopia development and progression.

Adolescent↗

PubMed2002

[Study on auditory brainstem response to bone conducted clicks].

OBJECTIVE: To observe how different vibrator placement and different stimulate rates affect the results of bone conduction ABRs. METHOD: Bone conduction ABRs with different vibratory placement and different stimulate rates were recorded in 20 normal hearing young adults and compared with their air conduction ABRs. RESULT: The results show that all subjects were recorded reproducible and reliable air and bone conduction ABR waveforms under higher intensities(above 40 dBnHL). The ABR thresholds from air and bone conduction were similar, they are both about 5-10 dB higher above their behavioral thresholds to clicks. The frontal placement produces significantly longer ABR wave V latencies. Bone conduction ABR wave V latencies from different stimulate rates were also observed. The results show that temporal placement ABR wave V latencies became longer significantly when the stimulate rate increased from 20/s to 52/s. CONCLUSION: Although it is affected by different vibrator placement and different stimulate rate, bone conduction ABR is a valuable and effective method to detect hearing, it plays an important role in newborn auditory screening, assessment of cochlear reserve, and identification of hearing loss.

Acoustic Stimulation↗