Agneta Rydberg

Reduced activity in the extrastriate visual cortex of individuals with strabismic amblyopia

In order to examine the relationship between reduced visual acuity in human strabismic amblyopia and the cortical activation pattern, we studied, by use of positron emission tomography (PET) and the H2(15)O bolus technique, changes in the regional cerebral blood flow (rCBF) induced by monocular visual stimulation of 8 individuals with this disorder. Individual amblyopic thresholds for monocular detection of the checkerboard pattern were employed as stimuli for both eyes during PET scans. Statistical analysis of subtracted images showed significant increases in rCBF (P < 0.05) by the stimulation of the sound eye localized bilaterally to Brodmanns areas (BAs) 17-19. The cortical response evoked by the amblyopic eye was significantly reduced (P < 0.05) in the ipsilateral BAs 18, 19. These results suggest that the reduction in contrast sensitivity (pattern vision) in amblyopia is coupled with deactivation in identifiable regions of occipital visual areas, including ipsilateral BAs 18,19.

Contrast sensitivity in 10 year old preterm and full term children: a population based study.

Aims: To determine the contrast sensitivity (CS) in 10 year old prematurely born children, previously included in a population based study on the incidence of retinopathy of prematurity (ROP), and in full term controls. Methods: This study included 205 prematurely born children and 215 children born at term, from the same geographical area and study period. CS was assessed monocularly with the Vistech 6500 test at five spatial frequencies (1.5–18 cycles/deg). Results: Prematurely born children had statistically significant lower CS at all frequencies, compared to full term ones. The mean differences in logarithmic CS were 0.03 (1.5 cycles/deg), 0.09 (3 cycles/deg), 0.10 (6 cycles/deg), 0.12 (12 cycles/deg), and 0.19 (18 cycles/deg). Even when the children with ROP and neurological disorders were excluded there was a difference between the two groups. Children who had been treated with cryotherapy had the lowest CS. Conclusion: CS was lower in 10 year old prematurely born children than in full term ones of the same age. Whether this finding affects their visual function in daily life is uncertain.

Visual functions in a Swedish population of dyslexic and normally reading children

Abstract Eighty‐six 9‐year old dyslexic children were carefully matched to controls with regard to age, sex, class in school, and intelligence and thorough visual functions tests and eye examinations were performed. As a group the dyslexic pupils exhibited a lower distance as well as near visual acuity both with monocular and binocular viewing. Furthermore, the dyslexic pupils had a lower contrast sensitivity at the lower and higher spatial frequencies. These differences were all statistically significant. However, no statistically significant differences between the two groups could be observed regarding refractive errors or contrast sensitivity in the middle spatial frequency range. Although some eyes were amblyopic, any severe eye anomalies or diseases were not found in any of the investigated children.

Oculomotor functions in a Swedish population of dyslexic and normally reading children

Abstract Eighty‐six nine‐year‐old dyslexic children were matched to control children with regard to age, sex, class in school, and intelligence. Orthoptic and eye movement analysis were performed on all children. It was concluded that the dyslexic pupils did not differ significantly from control children in terms of strabismus, accommodation, stereo acuity, vergence function or ocular dominance. Eye movement recordings did not show any qualitative differences between the groups in vergence dynamics during synoptophore investigations.

Orthoptic findings and asthenopia in a population of Swedish schoolchildren aged 6 to 16 years.

Purpose: To determine the prevalence of refractive errors and binocular disorders in relation to asthenopia in a representative population of Swedish schoolchildren. Methods: The study population included 216 schoolchildren, 60 in grade 1 (age 6–7 years), 96 in grade 4 (10–12 years) and 60 in grade 8 (14–16 years). Asthenopia was evaluated by questionnaire. Visual acuity was tested for distance and near, uncorrected and with the best subjective refraction. Refraction in cycloplegia and an orthoptic assessment was performed. Results: Asthenopia was reported in 23.1% of schoolchildren; all but two of these schoolchildren had an abnormal eye examination. Asthenopia was related to uncorrected visual acuity ≤ 0.65 (13.9%*) and myopia (8.8%*). No significant correlation could be found to accommodative or convergence insufficiency. Conclusion: Asthenopia was significantly associated with uncorrected visual acuity ≤ 0.65 and with myopia (spherical equivalent −0.50 D or less) among Swedish schoolchildren.

Visual field function in school‐aged children with spastic unilateral cerebral palsy related to different patterns of brain damage

Aim  To relate visual field function to brain morphology in children with unilateral cerebral palsy (CP).

Assessing visual function in children younger than 1 1/2 years with normal and subnormal vision: evaluation of methods.

PURPOSE Methods for detecting subnormal vision early in life are needed to adequately diagnose the condition and begin treatment and rehabilitation. METHODS Forty-six children ages 1 month to 1 1/2 years with either assumed normal vision, visual impairment due to eye disease, or strabismus were examined with the following tests: Stycar rolling balls; preferential looking (Teller acuity cards); and the ability to detect raisins, puffed rice, and sugar strands on two different backgrounds, one white and one black. RESULTS Children with visual impairment and strabismus often showed normal values for their age, and children with assumed normal vision sometimes had values below those established for normal development of vision with the Stycar rolling balls and the Teller acuity cards. CONCLUSIONS It is not possible to use these tests to reliably differentiate among normal vision, visual impairment, or strabismus in children younger than 1 1/2. Not until recognition acuity, symbols, or letters can be tested can reliable results be obtained. However, the tests are useful to estimate the general visual function of children in this age group.

The influence of accommodative insufficiency on reading.

Background:  It is not known how accommodative insufficiency influences reading performance.

Ophthalmological findings in 10-year-old full-term children : a population-based study

To determine different ophthalmological parameters in 10‐year‐old, healthy, full‐term children in Stockholm County, Sweden.

AMBLYOPIA SCREENING IN KINDERGARTENS WITH TNO STEREOTEST

One hundred and fifty children between 3 and 6 years old were screened for amblyopia with TNO stereotest in their kindergartens. Thirty screening positive children were found of whom 3 were amblyopic with strabismus and no stereopsis. Re‐testing showed that 19 children were false screening positive. Three children with refractive errors and equally impaired vision in both eyes were not detected. The test was found suitable for screening of monocular amblyopia in kindergartens, as it was easy to administrate and indicated all children with monocular amblyopia.