Visual function significantly distinguishes between children with and without mild academic problems, as well as on visual-perception scores. The high occurrence of visual deficits among participants warrants consideration of vision deficits among schoolchildren with academic performance difficulties.

No abstract

-A comparatively high incidence of ocular and orbital abnormalities has been reported in persons with Down syndrome. Eighty six children (50% male, 50% female) with Down syndrome in several institutions for individuals with learning diffi culties (age range 5-18 years, mean 12.5) were examined for visual impairment in order to relate the ocular impairment to the level of learning diffi culty. 6% had mild, 7% moderate, 45% severe and 42% profound learning diffi culty. 9% of the children had no refractive errors. A signifi cant (P<0.01) positive correlation was found between progressive amounts of strabismus and ocular pathology with increasing amount of learning diffi culty. On the other hand no correlation was found between refractive errors and the level of learning diffi culty. Due to the signifi cant number of ocular disorders found it is recommended that all children with Down syndrome should have an eye examination during the fi rst six months of life and annually thereafter.

In a group of chickens studied after lid suture in the first month post hatching an unusually high myopia was found (n = 8 eyes; average: -21.87 Diopters). The non-operated eyes of these chicks had the same optical properties (n = 4; +0.93 Diopters) as the eyes of the normal control chicks (n = 12; +0.81 Diopters). Although enlargement of the whole eye occurred, the main determinant was an axial elongation (operated eyes, 18.0 mm; nonoperated, 13.7 mm; normal controls, 14.7 mm). The axial change involves an enlargement of the posterior as well as the anterior segments of the eye. Despite several structural characteristics specific to chicks, their eyes can serve as a model for myopia research.

Monocular closure surgically performed during development by suturing the eyelids induced less hyperopia in the closed eye of light reared kittens (+0.95 Diopters) in comparison to the closed eyes of lid sutured dark reared kittens (+2.61 D). The normal control cats were also slightly hypermetropic (+0.69 D). While a certain proportion of myopic eyes was found in the monocularly closed light reared kittens and in the normal control cats, no one eye was myopic either in the operated or nonoperated dark reared kittens. Lid suture was found to considerably increase the hyperopia also in adult cats. The incidence of astigmatism was 47.0% for the closed eye in the lid sutured light reared kittens and 64.7% for their open eyes; for the lid sutured dark reared kittens the proportions were 45.4% and 54.5%, respectively. The incidence of astigmatism was 20.2% for the eyes of the normal control cats. Axial length of the closed eye of light (19.00 mm) and of dark (19.45 mm) reared kittens was smaller in comparison to that of the normal control cats (20.38 mm). The corneal curvature of the closed eyes of light (8.09 mm) and of the dark (8.64 mm) reared kittens was flatter than in the normal controls (7.11 mm). It is concluded that lid closure in kittens has a corneal effect, accentuating the tendency for hypermetropia naturally occurring in the dark. In the light lid closure results in an imbalanced combination of the corneal and the (axial?) visual deprivation effects, causing a considerable variability in the refractive error with a tendency for cancellation of the naturally occurring hyperopia.