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Biomedical subjects

J Gwiazda

Publications and source records attributed to J Gwiazda.

At least 37 records · Page 2Linked to original sources
PubMed1985

The development of visual acuity in infant astigmats.

Acuity for vertical, horizontal, and oblique gratings was measured in 77 infant astigmats using a preferential looking procedure. Measurements were made with the refractive error uncorrected. Most of the infant astigmats were slightly to moderately hyperopic with respect to the test distance of 50 cm. Their acuity was not significantly different from that of a group of non-astigmatic infants. Average acuity for vertical and horizontal gratings increased from 6/200 at 1 month of age to 6/24 at 1 yr. Average acuity for oblique gratings increased more slowly, so that by 1 yr of age it was only 6/33. The only infants to show reductions in acuity were those with a strong myopic focus and one infant with a very strong hyperopic focus. When this infant was tested with optical correction, acuity improved to normal levels. This suggests that meridional amblyopia develops sometime after the first year of life or that it is confined to high spatial frequencies.

Astigmatism↗
PubMed1984

Anisotropic resolution in children's vision.

Grating acuity was measured for 4 orientations in 111 children aged 3-8 yr. Results showed that 73% of the children had better acuity for horizontal and vertical compared to oblique gratings, 14% showed no anisotropy, and 13% had better acuity for oblique gratings. The magnitude of the oblique effect was 0.2 octaves, similar to that found in both younger children and adults.

Astigmatism↗
PubMed1984

Development of vernier acuity in infants.

The development of vernier acuity in human infants aged 2-9 months was assessed by a preferential looking procedure using a vernier-motion display. The displacement of vernier offsets gives the impression of motion only when the vernier offsets are detected. Grating acuity of the same group of infants was also measured by a preferential looking procedure. Vernier acuity was found to be superior to grating acuity only after 3 months of age. This superiority of vernier acuity was compared with the superiority of stereoscopic acuity to grating acuity. The two classes of hyperacuity proved to be almost equivalent in terms of their developmental time-courses. A common physiological basis for the development of hyperacuities is suggested.

Child Development↗
PubMed1984

Astigmatism in children: changes in axis and amount from birth to six years.

Noncycloplegic refractions of 1,000 children aged 0-6 years revealed a high incidence of astigmatism, especially in the first 2 years of life. Before age 41/2 years, most of the astigmatism was against-the-rule and after that age most was with-the-rule. Of 19 children who did not show astigmatism in the first year, only one acquired it by 4 years. Of 29 children who had large amounts of astigmatism in the first year, all showed elimination or a large reduction in the amount of the cylindrical error by 4 years. These results are relevant to the etiology of astigmatism.

Age Factors↗
PubMed1983

Visual acuity and its meridional variations in children aged 7-60 months.

A new operant procedure was used to assess grating acuity in children aged 7-60 months. The procedure was successful for 95% of the children sampled and had high test-retest reliability. Visual acuity for main axis (horizontal and vertical) gratings improved from 6/15 at 12 months to 6/6 at 60 months. For the 7-16 month age group, preferential-looking estimates of acuity agreed well with operant estimates. Acuity for oblique gratings was approximately 1/4 octave lower than main axis acuity throughout the age range. The results suggest that the human visual system continues to develop throughout the first 5 years of life.

Adult↗
PubMed1983

The development of vergence does not account for the onset of stereopsis.

The onset of measurable stereopsis in human infants occurs at approximately 4 months of age, directly following a period of rapid oculomotor development. The experiment reported here was designed to investigate whether the onset of stereopsis is determined solely by the onset of accurate oculomotor coordination or whether neural development in the binocular visual system is necessary. These alternatives were examined by means of a testing procedure which ensured that stimuli were presented within 1.4 deg of the horopter. That these stimuli are insensitive to errors of vergence was verified by testing thirty infants aged 6 to 10 months who were known to have stereoacuity of at least 1 min of visual angle. All but one infant retained the ability to make stereo discriminations with simulated vergence errors of up to 30 prism diopters. Results obtained from a group of forty-four infants tested longitudinally between 0 and 6 months showed a mean age of onset of stereopsis of 4.1 months. Thus, ensuring that stimuli are presented near to the horopter does not significantly alter estimates of the age of onset of stereopsis. These results suggest that neural development which is critical for the ability to make stereo discrimination must occur during the first 3 months of life.

Child Development↗
PubMed1982

Stereoacuity development for crossed and uncrossed disparities in human infants.

The development of stereoacuity for crossed and uncrossed disparities was assessed by means of a preferential looking procedure in a cross-sectional sample of infants aged 2-12 months and by following a longitudinal sample over the first 8 months of life. Crossed stereoacuity was found to develop earlier but at approximately the same rate as uncrossed stereoacuity. These data are consistent with the hypothesis that there exist two binocular mechanisms, one subserving disparity detection and one for uncrossed disparity detection.

Adult↗
PubMed1980

Stereoacuity of human infants.

Stereograms were presented in a two-choice preference procedure. The mean age at which stereopsis was first demonstrable was 16 weeks. By a mean age of 21 weeks, infants had achieved stereoacuity of 1 minute of arc or better. In comparison with the relatively slow development of visual acuity, the time course for the development of stereoacuity is extremely rapid.

Age Factors↗
PubMed1980

Quick assessment of preferential looking acuity in infants.

A simple and rapid method for assessing the visual acuity of infants can be a valuable tool for eye care specialists as well as for researchers in vision. We have developed a preferential looking (PL) procedure that uses simple equipment to obtain measures of PL acuity in a few minutes. Infants ranging in age from 2 weeks to 1 year can be tested. Sessions on infants without any visual problems are completed in less than 5 min. Computer simulations of the technique show that the fast procedure attains almost 80% accuracy in assessing infants' PL acuity thresholds. When PL acuity thresholds obtained by the 60-trial method of constant stimuli were compared to those obtained by the fast method on the same infants, they were identical on 70% of the sessions and only off by one-half octave in an additional 20% of the sessions. Interobserver reliability was also high. The ease and rapidity of the procedure make it appropriate for use in the clinic.

Age Factors↗
PubMed1980

Preferential looking acuity in infants from two to fifty-eight weeks of age.

The fast preferential looking procedure was used to obtain measures of acuity in a group of infants without visual problems whose ages spanned the 1st year of life. The results show an increase in acuity on horizontal and vertical square wave gratings from about 6/360 Snellen at 4 weeks of age to about 6/18 at 1 year. Acuity on obliquely oriented gratings (045) increases more slowly so that by 1 year of age it is only 6/36.

Age Factors↗
PubMed1978

Astigmatism in infants.

Compared with children of school age, infants show ten times the incidence and considerably greater amounts of clinically significant astigmatism. The amount begins to decrease in the second semester of life, and the incidence declines during the third year. The unanticipated results bear on both the etiology and the neural sequelae of astigmatism.

Age Factors↗