Blickrichtungsabhängige Visusbestimmung bei korrekt und falsch zentrierten asphärischen Einstärkenbrillengläsern

Abstract

Purpose. To investigate the effect on visual acuity of dis- regarding the centre of rotation requirement when using single vision aspheric lenses for correction of moderate to high hyperopes. Material and Methods. Two aspheric single vision lenses are fitted in each eye of 15 hyperopic subjects. One lens is exactly centred, the other lens is horizontally decentrated five milli- metres temporally. The interpolated LogMAR is then deter- mined in five different directions of gaze. The extent to which the LogMAR achieved differs between the lens with the observed centre of rotation requirement and the disregarded centre of rotation requirement in the individual directions of gaze is then examined. In addition, the influence of age is investigated. The results of the sub-samples “Age < 50 years” and “Age ≥ 50 years” are analysed descriptively. A clinically significant difference is defined as half a visual acuity level (corresponds to 0.05 LogMAR). Results. Significant differences in LogMAR between exact and incorrect centring could be determined for 30° nasal gaze (-0.09 LogMAR) and for 0° gaze through the lens (-0.07 LogMAR). Visual acuity was better with the precisely centred lens in each case. When testing for differences in LogMAR between the defined age-dependent subsamples, no signif- icant differences could be determined. Conclusion. The results show that the aberrations astigma- tism of oblique bundles and the image field curvature with the resulting deviation from refractive accuracy have less influence on visual acuity than previously assumed. Keywords spectacle lens centration, aspheric single vision lenses, centre of rotation requirement, astigmatism of oblique incidence, refractive accuracy