Power-adjustable spectacle lenses, based on the Alvarez-Lohmann principle, can be used to provide affordable spectacles for subjective refractive errors measurement and its correction. A new mechanical frame has been designed to maximize the advantages of this technology. The design includes a mechanism to match the interpupillary distance with that of the optical centers of the lenses. The fra...

Pterygium is known to affect refractive astigmatism, which can have a significant impact on vision. This study was undertaken to evaluate the effect of pterygium excision on refractive astigmatism. Thirty-six eyes with primary pterygium with astigmatism of 2D or more were analysed before and after pterygium excision. Astigmatism increased with the increase in the grade of pterygium (P = 0.00000...

The purpose of this study was to investigate the relationship between heterophoria and refractive error. Thirty-six subjects (11 myopes, 25 emmetropes) participated in this study. Heterophoria was measured with the Free-Space Phoria Card at five different viewing distances (25cm, 33cm, 50cm, 100cm and 300cm). Regardless of the types of heterophoria, the amount of heterophoria reduced towards or...

The method of isotropic photorefraction has been used in a trial of refractive screening of 6-9 month old infants. Data are presented on the calibration of the method against retinoscopic measurements and its reliability. In photorefractive screening of 1096 infants under cyclopentolate cycloplegia 5% were found to be hypermetropic (over +3.5 D), 4.5% myopic, and 1.3% anisometropic (over 1 D). ...

The detection of refractive errors includes effective screening programmes in the school or community. However, the lack of human and other resources often prevent such programmes from occurring. Therefore, patients with many conditions, both refractive and nonrefractive, present at clinics. The separation of these patients into refractive and non-refractive conditions is important in the good ...

Refractive errors are a common cause of decreased visual acuity. They can be found in 2-4% of preschool children. If not discovered on time and not properly treated, they can lead to amblyopia and strabismus. The active participation of parents and paediatricians is of great importance in timely discovering and treatment of amblyopia. The most common causes of amblyopia are strabismus (50.1%) a...