Abstract:
The ease of eye–drop extraction from its container has never been studied, although it may play an important factor in compliance to treatment in elderly or disabled patients. A model was designed to compare the strength required to extract drops from bottles of different manufacturers.
The model included a fixed portion to which the bottle was attached and a mobile portion – a lever with two arms. Mounting weights on the long arm led to squeezing of the bottle by the short arm. Weight for each bottle was determined in a staircase manner. Endpoint determined as the minimal weight (in grams) required to extract a drop from its container within 3 seconds. Three sets of 41 different topical agents were tested in a masked fashion. Statistical analysis was performed by ANOVA.
Six different groups of topical agents were tested. The table depicts for each group the force range (in grams) required to squeeze a drop out of the bottle.
When comparing agents of similar biochemical mechanism a significant difference was found among the beta– blockers, parasympatholytics and quinolone groups. No significant difference was found among the prostaglandin analogs, carbonic anhydrase inhibitors and aminoglycoside groups. This model produces a value which integrates the factors that may contribute to the force required to squeeze an eye–drop from its container. The results show a large variation among bottles. This may need to be taken into consideration when prescribing eye–drops to older individuals or patients with arthritic hand problems.
Keywords: pharmacology • quality of life • aging