Comparison of progressive addition lenses for general purpose and for computer vision: an office field study

Abstract

Background: Two types of progressive addition lenses (PALs) were compared in an office field study: 1. General purpose PALs with continuous clear vision between infinity and near reading distances and 2. Computer vision PALs with a wider zone of clear vision at the monitor and in near vision but no clear distance vision. Methods: Twenty-three presbyopic participants wore each type of lens for two weeks in a double-masked four-week quasi-experimental procedure that included an adaptation phase (Weeks 1 and 2) and a test phase (Weeks 3 and 4). Questionnaires on visual and musculoskeletal conditions as well as preferences regarding the type of lenses were administered. After eight more weeks of free use of the spectacles, the preferences were assessed again. The ergonomic conditions were analysed from photographs. Results: Head inclination when looking at the monitor was significantly lower by 2.3 degrees with the computer vision PALs than with the general purpose PALs. Vision at the monitor was judged significantly better with computer PALs, while distance vision was judged better with general purpose PALs; however, the reported advantage of computer vision PALs differed in extent between participants. Accordingly, 61 per cent of the participants preferred the computer vision PALs, when asked without information about lens design. After full information about lens characteristics and additional eight weeks of free spectacle use, 44 per cent preferred the computer vision PALs. Conclusion: On average, computer vision PALs were rated significantly better with respect to vision at the monitor during the experimental part of the study. In the final forced-choice ratings, approximately half of the participants preferred either the computer vision PAL or the general purpose PAL. Individual factors seem to play a role in this preference and in the rated advantage of computer vision PALs.

The vertical monitor position for presbyopic computer users with progressive lenses: how to reach clear vision and comfortable head posture

“…The present preferred gaze inclination of about 2 208 with a range from 2 108 to 2 308 corresponds to conclusions based on biomechanical modelling (Straker et al 2009) and resembles the finding of other recent studies (Allie, Purvis, and Kokot 2005, 2010Meinert, König, and Jaschinski 2013;Jaschinski et al 2015b). This range is in accordance with the average vertical zone of clear vision for general-purpose progressive lenses (Figure 1).…”

“…This corresponds to findings in a field study where participants changed from general-purpose progressive lenses to computer vision progressive lenses which induced a lower head inclination by 2.38 and a decrease in musculoskeletal symptoms (Jaschinski et al 2015b). These intra-individual comparisons are sensitive enough to show that small changes in head inclination of a few degrees can be relevant for symptoms.…”

“…In this way, the participants became acquainted with the procedure; even if single untypical postures may have been measured, these data will little affect the average of a series per day. The present method has been proven as useful in our previous studies because we found reliable individual changes in workplace postures after an office intervention (Meinert, König, and Jaschinski 2013) and a significantly higher head inclination by 2 -78 in users of generalpurpose progressive lenses (Jaschinski et al 2015a(Jaschinski et al , 2015b. The present results on head inclination in Figure 8 based on intra-individual comparisons further confirm this procedure.…”

Computer vision syndrome in presbyopia and beginning presbyopia: effects of spectacle lens type

“…Among the participants who agreed to this procedure, the ergonomic conditions were assessed, based on side‐view photographs . The participants were asked to maintain a normal working posture and look at the centre of the monitor.…”

How to place the computer monitor: measurements of vertical zones of clear vision with presbyopic corrections

“…The mean and SD of the corresponding distance refraction were 0.33 ± 0.09 D, with an average maximum intermediate distance of 3.03 metres. The geometrical profiles of near vision addition of these lenses are illustrated in a parallel study . All subjects received a subjective refraction of both eyes by a certified optometrist (co‐author MK), using a letter chart at six metres distance and trial lenses.…”