Biomedical subjects

E E Hartmann

Publications and source records attributed to E E Hartmann.

7 recordsLinked to original sources

PubMed1992

Temporal contrast sensitivity in human infants.

Temporal contrast sensitivity was measured in 1.5- and 3-month-old infants using the FPL procedure. Stimuli were 0.1 c/deg counterphase-flickering sinewave gratings. Temporal rates ranged from 1 to 20 Hz. Because the spatial sinewave underwent phase shifts of 180 degrees, the target could not be seen unless the observer was able to resolve it temporally. Adults were tested with the same temporal stimuli using a 2-alternative forced-choice procedure and a spatial frequency of 0.5 c/deg. Adult temporal CSFs were bandpass with peak sensitivity at 10 Hz. Infant temporal CSFs were lowpass at 1.5 months and bandpass at 3 months. The infants' contrast sensitivity was over a log-unit lower than adults'. Unlike spatial CSFs, infant sensitivity was closest to adult sensitivity at the highest flicker rate.

Adult↗

PubMed1990

Visual acuity estimates in noncommunicative elderly persons.

The acuity card procedure has been shown to provide reliable grating acuity estimates in pediatric patients. The current study was conducted to determine the usefulness of this procedure in another group of persons in whom conventional acuity measurements are not possible, ie, nursing home residents who suffer from dementing disorders. Binocular visual acuity estimates were obtained in 13 cognitively impaired nursing home residents. Test sessions took 20-30 min each. Both test-retest agreement and inter-observer agreement of Teller Acuity Card (TAC) acuity estimates were good (within 0.5 octave for all residents), demonstrating that this procedure yields reasonable acuity estimates in noncommunicative nursing home residents. The authors stress the potential of this tool for nursing home administrators as well as for researchers.

Aged↗

PubMed1989

Electrophysiologic testing techniques for children.

This practical article for clinical electrophysiologists discusses the evaluation of infant and child patients' visual systems using electroretinographic (ERG), electrooculographic (EOG), and visually evoked potential (VEP) techniques. These techniques not only help to secure specific diagnoses, but by systematic assessment of function along the visual pathways can also localize dysfunction underlying visual deficits of pediatric patients. Among children, development as well as disease can affect electrophysiological parameters. Therefore diagnosis of normal or abnormal depends critically on an adequate description of normal responses for age. Procedures that the authors have found feasible, reliable, and valid are summarized. Standardization of pediatric testing appears to be an important next step. The power of ERG, EOG and VEP recordings to demonstrate the neurophysiological basis for pediatric visual impairment is predicted to stimulate further research in this area.

Adult↗

PubMed1988

Teller acuity cards versus clinical judgment in the diagnosis of amblyopia with strabismus.

Teller acuity card testing, which is a form of the preferential-looking procedure, is a popular way of assessing visual acuity in preverbal patients. The authors suspected that the clinical judgment of a pediatric ophthalmologist is superior to the Teller acuity cards in diagnosing amblyopia when strabismus is present. Acuity card and fixation preference measurements on each eye were compared at the same clinical visit in a group of 108 strabismic patients. The authors found that the acuity cards could be used to detect amblyopia. However, the pediatric ophthalmologist was more sensitive in diagnosing amblyopia than the Teller acuity cards in the presence of strabismus.

Amblyopia↗

PubMed1985

The development of basic mechanisms of pattern vision: spatial frequency channels.

The mature visual system possesses mechanisms that analyze visual inputs into bands of spatial frequency. This analysis appears to be important to several visual capabilities. We have investigated the development of these spatial-frequency channels in young infants. Experiment 1 used a masking paradigm to test 6-week-olds, 12-week-olds, and adults. The detectability of sine wave gratings of different spatial frequencies was measured in the presence and the absence of a narrowband noise masker. The 12-week data showed that at least two spatial-frequency channels with adultlike specificity are present at 12 weeks. The 6-week data did not reveal the presence of narrowband spatial-frequency channels. Experiment 2 used a different paradigm to investigate the same issue. The detectability of gratings composed of two sine wave components was measured in 6-week-olds and adults. The results were entirely consistent with those of experiment 1. The 12-week and adult data indicated the presence of narrowband spatial-frequency channels. The 6-week data did not. The results of these experiments suggest that the manner in which pattern information is processed changes fundamentally between 6 and 12 weeks of age.

Adult↗

PubMed1979

The maturation of vestibular nystagmus in infancy and childhood.

The displacements, durations, and velocities of the slow and fast components of both the primary and secondary nystagmus induced by constant angular acceleration were measured in 46 normal children 1 month to 11 years old. There were significant changes in nystagmus parameters in respect to maturation. The young infant had larger amplitude, higher velocity beats than the older child during both the primary and the secondary nystagmus. Parameters describing both the primary and the secondary nystagmus reached their peak values and terminated earlier in the infant than in the older child. Although the slow component velocity during secondary nystagmus was much slower than during the primary nystagmus at all ages, the secondary nystagmus/primary nystagmus ratio was significantly greater in early infancy. Thus, in infancy, as compared with later childhood, the vigor of the secondary nystagmus was disproportionately greater than the primary nystagmus. These results were discussed in relation to the maturation both of vestibular responsiveness and of vestibular adaptation.

Age Factors↗

PubMedDate not supplied

The acuity card procedure: longitudinal assessments.

Traditional methods of visual assessment in preverbal pediatric patients rely on refined but subjective measurement techniques. A standard ophthalmologic examination includes evaluation of a child's fixation patterns, with performance ranked on the basis of ability to fix and follow an object (F & F) or maintain central, steady fixation (CSM). In the hands of a skilled clinician, these evaluations are important for diagnosis and treatment. Documentation of quantitative changes in visual abilities of preverbal patients, however, has only recently become feasible. We began using the acuity card procedure in our pediatric clinical practice more than 3 years ago. This assessment, a modified version of the standard Forced-Choice Preferential Looking paradigm (FPL), provides quantitative evaluation of visual functioning in preverbal patients. The total number of patients assessed on one or more occasions exceeds 900. Of this group, we followed 83 patients with at least four acuity card evaluations on separate visits. Thirty of these patients, all with different diseases, have been evaluated with acuity cards on six or more visits. We found the information provided by the acuity card assessments extremely helpful in quantifying the developmental and therapeutic changes in vision, previously monitored only qualitatively.

Child, Preschool↗