“…(2,4,8) The volume of drops dispensed from a bottle of eyedrops depends on several factors, among which: A) The physicochemical properties of the solution (surface tension, viscosity and density) (4,5,9,10) ; B) The design of the bottle along with its geometry, the material with which the bottle is manufactured, its stiffness (resistance to the force applied), and in particular the diameter of the external orifice of the eyedropper nozzle, which are important to determine the volume of the drops dispensed. (Figura 1) (3,5,9) ; C) The strength made during instillation, the handling of the eyedrops bottle by the patient, how fast the drop is formed, and the position of the bottle in relation to the ocular surface are also factors to influence the final volume of the drop formed . (5,6,11) The lack of uniformity in the volume of drops dispensed from the bottles of eyedrops is a reason for attention due to waste, especially when it comes to expensive eye drops like those used to treat glaucoma patients.…”