Do best practice guidelines improve the legibility of pharmacy labels for the visually impaired?

Abstract

Reading pharmacy labels on medications is a challenging task for visually impaired people. Design for Patient Safety (DfPS) best practice guidelines exist on the presentation of information on pharmacy labels, but it is unclear to what extent current labels follow the guidance. It is also unclear whether labels produced to DfPS guidelines are more accessible to patients with impaired vision. Twenty-four sample labels were obtained from six different pharmacy chains. Experimental labels were constructed reflecting a typical pharmacy label, an ideal label constructed to DfPS guidelines, and a large print label. 20 normally-sighted subjects read labels under habitual conditions (mean VA -0.14 log MAR, Snellen equivalent 6/4.4), and under two conditions of simulated visual impairment (mean VA +0.41 and +0.69 logMAR, Snellen equivalents 6/15.4 and 6/29.4). Outcome measures were speed and accuracy of label reading. Median font size for the primary directions on the sample labels was 9.5 point (range 8-10 point), rather than the recommended minimum size of 12 point. In the mild visual impairment condition, using the ideal label improved accurate reading speed by 58% over the typical label, and using the large print label improved accurate reading speed by about 100%. In the moderate visual impairment condition, 65% of subjects were able to see sufficient of the directions to be able to take the medication appropriately with the ideal label, and 80% with the large print label, as compared to 20% with the typical label. DfPS best practice guidelines were not fully met by any of the pharmacy labels in this sample. With unimpaired vision, label design had little impact on legibility. However, the results provide evidence that preparing pharmacy labels according to DfPS guidelines improves their relative legibility in simulated visual impairment. These findings need extending to those with actual visual impairment, but the current results strengthen the argument for conformance to DfPS guidelines.