Background Self-application of topicals on the back can be challenging. Objective The aim was to assess topical back coverage using commercially available back applicators. Materials and Methods Ten subjects applied sunscreen to their back using their hands and then with 3 back applicators (large foam tip, small foam tip, roller tip). The amount of lotion used and the time it took to perform the application were recorded. The resulting distribution of sunscreen was assessed with a Wood’s lamp; the area covered fluoresced less than the uncovered skin. Images were captured and then analyzed using an automated thresholding technique. Results Subjects applied more lotion when using the large foam tip (7.58 g, 95% CI 6.47-8.70 g; P < .004) and small foam tip (7.46 g, 95% CI 6.35-8.57 g; P < .006) applicators compared to hands alone (6.22 g, 95% CI 5.10-7.33 g). Application time was longer with the small foam tip applicator (113.4 s, 95% CI 96.7-130.1 s) relative to hand application (78.7 s, 95% CI 62-95.4 s) ( P < .03). Coverage of the back was higher for the large foam tip (84.8%, 95% CI 78.4%-91.3%; P < .03), small foam tip (88.0%, 95% CI 81.6%-91.5%; P < .006), and roller tip (84.3%, 95% CI 77.9%-90.8%; P < .04) applicators compared to hand application (71.5%, 95% CI 65%-78%). The middle back tended to have less coverage when applying with the hands. Conclusions Topical coverage of the back is improved with the use of applicator devices during self-application.
Automated thresholding algorithms outperform manual thresholding in macular optical coherence tomography angiography image analysis
