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Education, Professional↗
Biomedical subjects
Josephine Shallo-Hoffmann
Publications and source records attributed to Josephine Shallo-Hoffmann.
Maximum angle of ocular duction during visual fixation as a function of age.
PURPOSE: To measure and compare the maximum angle of ocular duction in healthy individuals as a function of age. METHODS: A calibrated arc perimeter was modified to display one of six randomly presented targets (high contrast Snellen equivalent letters), in both vertical (supra/infraduction) and horizontal (ab/adduction) gaze to the dominant eye of 204 healthy volunteers with best-corrected visual acuity. A bite-bar and headrest were employed to prevent head movement. Using a modified method of limits for discrimination threshold, a maximum mean angle of ocular duction was determined by stepping a target out in 5 degrees steps until an error was reported and thereafter bracketing around the limits of the target identification in 1 degrees steps. A mean threshold value was determined as the angle at which a subject obtained a correct response 75% of the time in two and as many as the trails in each of the four randomly presented directions of gaze (abduction, adduction, supraduction and infraduction). RESULTS: A decrease in mean maximum duction angle was found over all age groups in al four directions (p < 0.001), with a step decline beginning in the sixth decade and almost doubling in the oldest age group tested (80-95 years-olds). The percent change in mean maximum angle of duction due to age from the 14-19 to the 80-95 year-olds was: abduction 21%, adduction 24%, supraduction 35%, infraduction 26%. CONCLUSION: Baseline data are useful to differentiate normal changes occurring with age from early signs of disease. AdditIonally, disease progression and effects of treatment can be monitored.
Adolescent↗
A study of pre-school vision screening tests' testability, validity and duration: do group differences matter?
Vision screening was performed on 268 pre-school children: 170 from a private pre-school, 33 from a Caribbean-American parochial pre-school and 65 pre-school children from a clinic serving indigent Spanish farm-workers. Using a multi-station format, a stereoacuity test and two visual acuity tests were performed during a single screening session. The time it took to complete a test was recorded. To pass the screening, children were required to pass one visual acuity test and the stereoacuity test. Children who could not complete the protocol were retested at a later date. Children who failed the screening and every fourth child who passed the screening were referred for a full eye examination. The parents and teachers were masked to the results of the screening as well as the optometrists who performed the eye examination. Sensitivity, specificity and accuracy scores were 100%, 79% and 80%, respectively. Three-year-old children completed the Lea Symbol Chart more often than the HOTV. No differences in time required to complete a visual acuity test were found. The Lea Symbol chart is more likely to be completed by young children. Testability changes significantly with age rather than with the instrument when socio-ethnic factors are held constant. Differences among groups and the sensitivity of the screening are discussed.
Child↗
Visual motion detection in patients with absent vestibular function.
Labyrinthine defective subjects (LDS) experience oscillopsia during head movements due to the absence of the vestibulo-ocular reflex (VOR). The purpose of this study was to compare horizontal and vertical visual motion detection in LDS during (i) body-stationary and (ii) horizontal whole-body oscillation conditions. Twelve LDS and controls detected the onset of drift direction of a grating that moved with accelerating velocity. Thresholds were raised in the patient group in both conditions. The loss of the VOR per se cannot explain raised thresholds in the body-stationary condition nor during whole-body (horizontal) oscillation with vertical grating motion. Findings indicate changes in visual processing that make LDS less sensitive to visual motion. It is postulated that these changes are due to adaptive mechanisms involved to reduce oscillopsia.
Adult↗