ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

Purpose:This study compares the development of acuity in the same infants during one testing session using Teller acuity cards (TAC) and sweep visual evoked potentials (sVEP). We asked whether different testing methods in two centers would produce different developmental time courses.Methods:Forty-eight infants were tested in two centers. The standard procedure for TAC was used. For sVEP acuity, the amplitude response curve derived from time-locked cortical activity was used to extrapolate to zero response, giving an acuity estimate for each infant.Results:sVJEP acuity was generally higher than TAC acuity. The rate of development was steeper for TAC than sVEP acuity with TAC starting at a much lower level. The ratio of sVEP to TAC acuity decreased exponentially with age reaching an asymptote of about 1.44 at 6 months.Conclusions:Results were indistinguishable between centers suggesting that comparison of acuity measures obtained using variations of these methods across centers is possible.

ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

An objective visual evoked potential (VEP) technique was developed to evaluate spatial processing in humans over a wide range of ages. The constellation of stimulus conditions and analysis methods constitute a novel tool for the assessment of neural development. The key points that delineate this VEP technique are: (1) A brief, 6-s, swept-parameter stimulus with spatial frequency of square-wave grating patterns varied in octave steps, which facilitates correct accommodation and increases the likelihood of collecting uninterrupted, useable data; (2) data collection synchronous with stimulus presentation, which prevents contamination of the relevant frequency component from other frequency components in the response, thereby increasing the signal-to-noise ratio; (3) noise estimation at the response frequency of interest (second harmonic), based on a multivariate statistic (T2circ), which yields a realistic measure of signal-to-noise; (4) estimation of grating acuity from linear interpolation of the signal-to-noise measure; (5) monocular testing followed by multivariate statistical comparison of fellow eye data for each spatial frequency condition, which enables the determination of asymmetries within monocular neural pathways; (6) evaluation of maturation of the visual system based on vector-averaged amplitude and phase measures. Preliminary results indicate that reliable response functions are obtained from infants, children, and adults. Acuity estimates increased as a function of age. Phase values decreased consistently with increases in spatial frequency greater than 4 c/deg. Infants produced larger peak amplitude responses than did older observers, consistent with known developmental changes in cortical synaptic density. Phase data for the 2 c/deg condition provided additional evidence for the lack of maturity in the infant visual system as compared with that of older observers.

ISSN:1040-5488    

出版商:OVID    

年代:1997

数据来源: OVID