makes it impossible to express the results in a general and informative manner. We felt, therefore, that it was useful to define two index that can be used for the purposes of such analysis. Metho& The axial and toric components of ametropia are such that it can be seen as a point within a threedimensional reference. The distance between the point and the centre of a reference defines the Refra...

AIM To investigate risk factors associated with strabismus in children born prematurely. METHODS Prospective study of all children born before 32 weeks' gestation between 1 January 1990 and 31 December 1991 in a geographically defined population of approximately 3 million in the Northern Region of the United Kingdom. All children were examined aged 2 years by the same ophthalmologist and paed...

PURPOSE There is currently great interest in comparing data for the prevalence of myopia in different parts of the world, particularly in view of the suggestion that, in recent decades, marked increases have occurred in prevalence among children and young adults in some areas. This work investigates the factors that affect the comparison and interpretation of sets of myopia prevalence data for ...

Rapid assessment methods Rapid assessment methods are a means to undertake a comprehensive assessment of a public health issue using minimum resources within a limited amount of time. Such methods help plan, develop and implement interventions and monitor service delivery. These methods are typically useful in situations where data are needed quickly, and time and cost factors prohibit the use ...

Detection and resolution acuity was measured at 30 degrees in the periphery for sinusoidal gratings under differing amounts of optical defocus. Within the range -2.0 to +2.5 diopters defocus, detection acuity was higher than resolution acuity. As defocus increased, detection acuity decreased continuously but resolution acuity was little affected until around 2.0 diopters defocus. The results in...

Many people coming to eye clinics have refractive errors and can have their vision improved by spectacles (glasses). Most of these can be tested by general eye health workers without special training and using only a trial set of lenses. It is also useful to find out quickly which people do not have refractive errors and do not need glasses. Most errors can be corrected satisfactorily with sphe...

The distribution of refractive errors was followed in chicks from hatching to 8 weeks of age. A dramatic progressive decrease in the variability of refractions was observed over this period. In addition, there appeared to be a parallel decline in hyperopia, even when the artifactual hyperopia of retinoscopy was taken into account. These results are evidence for a postnatal development regulator...

Distance and size estimates and stereoacuity judgments were made in water by divers, both with and without facemasks. Without the mask, only stereoacuity was markedly degraded. Distance estimates were slightly more accurate, despite a great decrease in the range of visibility. Size estimates were slightly too small. Divers with refractive errors did not appear to be more handicapped than those ...

We investigated differences in higher order monochromatic aberrations between hyperopic and emmetropic eyes from two large cohorts (mostly 6 and 12 year old) of Caucasian children. Additionally, we investigated the differences of higher order monochromatic aberrations between age groups. In both cohorts, hyperopic eyes had significantly higher levels of positive spherical aberration (SA) and hi...