Force requirements in topical medicine use—the squeezability factor

Connor, Alan; Severn, Philip

doi:10.1038/eye.2011.5

Cited by 36 publications

(30 citation statements)

References 9 publications

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“…A similar range of pressure required to expel a drop with various glaucoma and other topical ophthalmic medication bottles has been found previously 10. Droppers that required the highest mechanical pressures to expel a drop in this study would cause over 50% of subjects discomfort in their attempt to do so (ie, was more than their objectively measured maximum comfortably exerted squeeze pressure), which is likely to affect compliance and hence treatment efficacy 3.…”

Section: Discussionsupporting

confidence: 72%

Usability of prostaglandin monotherapy eye droppers

Drew

Wolffsohn

2015

Br J Ophthalmol

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Subtitle:The force required to expel a drop differs between Prostaglandin monotherapy dropper designs and some exceeded the maximum force that could be comfortably applied by around half the population, which may affect compliance and efficacy. 2 ABSTRACTAim: To determine the force needed to extract a drop from a range of current prostaglandin monotherapy eye droppers and how this related to the comfortable and maximum pressure subjects could exert. Methods:The comfortable and maximum pressure subjects could apply to an eye dropper constructed around a set of cantilevered pressure sensors and mounted above their eye was assessed in 102 subjects (mean 51.2±18.7 years), repeated 3 times. A load cell amplifier, mounted on a stepper motor controlled linear slide, was constructed and calibrated to test the force required to extract the first 3 drops from 13 multi-dose or uni-dose latanoprost medication eye droppers. Results:The pressure that could be exerted on a dropper comfortably Conclusions:Prostaglandin monotherapy droppers for glaucoma treatment vary in their resistance to extract a drop and with some a drop could not be comfortably achieved by half the population, which may affect compliance and efficacy.3

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Section: Discussionsupporting

confidence: 72%

Usability of prostaglandin monotherapy eye droppers

Drew

Wolffsohn

2015

Br J Ophthalmol

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“…This is of particular importance in ophthalmology where patients may have difficultly in administering different topical preparations 6. Our audit indicated that 1 in 10 patients had missed a drop after the generic switch, and none were able to use their Xal-ease devices.…”

mentioning

confidence: 86%

Authors' response: generic medications in ophthalmology

Connor

Fraser

2013

Br J Ophthalmol

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“…11,12 In the only three published studies on the topic, investigators evaluated a small sample of ophthalmic medications and found a wide variation in the force required to deliver a single drop. 13,14,15 We hypothesize that 1) the multitude of generic and brand glaucoma medications require significant variability in force required to dispense a single drop, 2) the force requirements differ based on the amount of solution remaining in the bottle, 3) the force requirements differ based on the angle the bottle is held and 4) the force requirement to dispense a drop in certain bottles will exceed some patients’ strength to squeeze them. This study was designed to determine the force requirements to deliver a single drop from each of the commonly prescribed brand and generic topical glaucoma bottles and correlate these findings with pinch strength in a representative glaucoma patient population.…”

Section: Introductionmentioning

confidence: 99%

Squeeze Me if You Can: Variability in Force Requirements to Extract a Drop From Common Glaucoma Bottles

Moore

Hammer

Akhtari

et al. 2016

Journal of Glaucoma

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Purpose To determine the force requirements to dispense a single drop from commonly prescribed brand and generic topical glaucoma medications and correlate these findings with pinch strength in a representative patient population. Patients and Methods Four bottles of each medication were tested: two in the vertical and two in the horizontal orientation. Bottles were housed in a customized force gauge apparatus designed to mimic ballpoint fingertip contact with a bottle tip. For all bottles, each of the first 10 dispensed drops was tested and then tests were performed in increments of 10 until the bottle was empty. For each tested drop, the maximum force and displacement were electronically measured. Concurrently, maximum pinch strength was measured on consecutive glaucoma patients. Results A total of 84 bottles from 21 bottle designs were tested. There was significant variability across the designs, with roughly a 7-fold (0.67–4.49 kilograms of force, kgf) and 4-fold (0.81–3.00 kgf) difference in force requirements in the vertical and horizontal positions, respectively. Of 53 enrolled patients in the glaucoma clinic, the mean pinch strength was 5.05 (range 1.23–10.4) and 4.82 (range 1.47–10.67) kgf for the right and left hands, respectively. Conclusions There is statistically significant variability in the force required to squeeze a drop from common glaucoma medications, and a representative sampling of clinic patients suggests that many likely struggle with the force requirements of several bottle designs. These data further support standardization of topical glaucoma drug delivery and design.

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Force requirements in topical medicine use—the squeezability factor

Cited by 36 publications

References 9 publications

Usability of prostaglandin monotherapy eye droppers

Usability of prostaglandin monotherapy eye droppers

Authors' response: generic medications in ophthalmology

Squeeze Me if You Can: Variability in Force Requirements to Extract a Drop From Common Glaucoma Bottles

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