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...

PURPOSE The development of emmetropic refraction is known to be under visual control. Does partial spectacle correction of infants' refractive errors, which has been shown to have beneficial effects in reducing strabismus and amblyopia, impede emmetropization? The purpose of the present study was to perform the first longitudinal controlled trial to investigate this question in human subjects. ...

PURPOSE To evaluate whether visual target character and visibility affects spontaneous eye blink rate (SEBR) in primary eye gaze and silence. METHODS Video recordings were made of young healthy adults who were either emmetropic (n=32) or who wore spectacles for refractive error (range -4.75D and +4.50D (n=31). Emmetropes had 5min recordings made whilst seated and looking towards a distant whi...

PURPOSE To describe spherical equivalent (sph eq) refractive errors in preschool members of a Native American tribe with a high prevalence of astigmatism. METHODS Cycloplegic autorefraction measurements were obtained for 819 three- and four-year-old Tohono O'odham children, with follow-up measurements in 146 after 4 to 8 years. RESULTS Mean sph eq was significantly more hyperopic in the ast...

The relationship between accommodative lag and annual myopia progression was investigated using linear models in 592 myopic children wearing a full refractive correction in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study. The mean (± SD) age and spherical equivalent refractive error at baseline were 10.4 ± 1.8 years and -2.13 ± 1.24 D, respectively. Th...

Exceptional vision is needed to maintain high levels of aviation performance. Current standards for helicopter pilot training include superior visual acuity with minimal refractive error. Despite these demanding criteria, it is likely that visual ability varies among those who meet the standards for pilot training. A more complete knowledge of visual capabilities in these individuals will allow...

PURPOSE To determine the precision (repeatability) of several methods of calculating refraction from higher-order wavefront aberration data and to compare these wavefront refractions with lower-order (LO) wavefront refraction, subjective refraction, and autorefraction. METHODS Four clinicians refracted 16 normal participants aged 23.6 +/- 1.2 years, 69% female with an average spherical equiva...

We develop formulas for calculating the approximate depth of focus of any eye. They show that the magnitude of depth of focus is inversely proportional to the size of the eye and to its visual acuity. One particular implication of these quantitative relations. which is supported by previous data from rats and human infants, is that small eyes with low acuity should have large depths of focus. W...

Results: The prevalence of significant refractive error was 5.2%, 75/1439, (95% CI) being responsible for 92.6 % of all causes of poor eyesight. Hypermetropia accounted for 3.2% (95% CI), myopia 1.7% (95% CI) and astigmatism 0.3% (95% CI) of refractive errors. Myopia was more likely to be present in the pupils aged 14 to 15 years than those aged 12 to 13 years with OR 2.9 (0.1 – 9.2) which was ...