April 2014
Volume 55, Issue 13
ARVO Annual Meeting Abstract  |   April 2014
Usability of Glaucoma Medication Eye Droppers
Author Affiliations & Notes
  • Thomas Edward Drew
    Life and Health Sciences, Aston University, Birmingham, United Kingdom
  • James Stuart Wolffsohn
    Life and Health Sciences, Aston University, Birmingham, United Kingdom
  • Footnotes
    Commercial Relationships Thomas Drew, None; James Wolffsohn, Thea (F)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 536. doi:
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      Thomas Edward Drew, James Stuart Wolffsohn; Usability of Glaucoma Medication Eye Droppers. Invest. Ophthalmol. Vis. Sci. 2014;55(13):536.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: To determine the force needed to extract a drop from a range of current glaucoma medication eye droppers and how this related to the comfortable and maximum pressure patients could exert.

Methods: The comfortable and maximum pressure patients could apply to an eye dropper [vial or unit-dose (UD)] constructed around a set of cantilevered pressure sensors (Richmond Industries, UK) and mounted above the patients eye was assessed in 40 patients aged 19-85 years repeated 3 times. A load cell amplifier (Richmond Industries, UK) mounted on a stepper motor controlled linear slide (Trinamic GmbH, Germany; Geckodrive Inc., USA) was constructed to test the force required to extract the first 6 drops from glaucoma medication eye dropper : 4 generics latanoprost (50 µg/ml) vials of 2.5 ml, preservative free bimatoprost (0.3mg/ml) 0.4 ml UD, preservative free tafluprost (15 µg/ml) 0.3ml UD, travoprost (0.004% 40 µg/mL) vial of 2.5 ml, latanoprost (0.005%) vial of 2.5ml, bimatoprost 0.1mg/ml vial of 3ml, bimatoprost 0.3mg/ml vial of 3ml and preservative free latanoprost (50µg/ml) 0.2ml UD.

Results: The pressure that could be exerted on a dropper comfortably (30.8 ± 17.0 newtons, range 7.3 to 85.6) could be exceeded with effort (to 62.9 ± 25.6 newtons, range 33.2 to 130.9), but did not differ between repeats (ANOVA F = 2.178, p = 0.120). Comfortable and maximum pressure exerted were correlated (r = 0.769, p < 0.001), but neither were influenced strongly by age (r = 0.084, p = 0.605; r = -0.113, p = 0.489 respectively). The force needed to exert successive drops from each individual dropper design did not alter (F = 0.662, p = 0.447), but this did differ between dropper designs (F = 26.882, p < 0.001) with the force required ranging from 6.7 to 24.3 newtons. Preservative free latanoprost 50 µg/mL 0.2ml UD and latanoprost 0,005% vial of 2.5ml required significantly less force applied to exert a drop than the other eye droppers (p < 0.001).

Conclusions: Glaucoma medication droppers vary in their resistance to extract a drop and this could only be comfortably achieved by all patients with preservative free latanoprost 50 µg/mL 0.2ml UD and latanoprost 0,005% 2.5ml vial. Patients would struggle with other dropper designs and this may affect compliance and efficacy.

Keywords: 465 clinical (human) or epidemiologic studies: systems/equipment/techniques  

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