Lens decentration of spectacle wearers

Abstract

Lens decentration equals the difference of the distance between the optical center and pupil distance. Though this could lead into various visual problems, it had not been taken into consideration since measurement on pupil-distance rarely conducted while producing spectacles. Determining whether spectacle wearers encountered lens decentration, 89 bespectacled students (ages 18-22 years-old) at STIKes Bakti Tunas Husada Tasikmalaya were examined. Their optical center was measured using lens meter, and their pupil distance was measured by pupil distance ruler. All measurements were performed while subjects were wearing spectacles on a daily basis. The findings reveal that the average interpupillary distance was 63.2 mm ± 7.63 mm and optical center was 63.53 mm ± 8.54 mm. Furthermore, there was 64.1% spectacle lens categorized as 'no decentration' and 35.9 % spectacle lens categorized as 'decentration'. The researcher also found out that the lens decentration has maximum decentration of 3-5 mm for both eyes. Thus, it can be concluded that some of the spectacle wearers have lens decentration which can lead to induced prismatic effect and causes further visual impairments such as asthenopia or diplopia in the future.