I have to put meds in my eye three times a day (glaucoma), and am wondering just how precise a dosage “one drop” is. Given the physics (size of hole and specific gravity of solution), I’d guess it to be pretty precise. But does how hard I squeeze alter that any? Dosage probably isn’t important anyway in that much of the medication runs down my cheek. Just curious. 
Peace,
mangeorge
Well, eyedrops are tested for dose size during development and clinical testing, but it’s always a bit more variable than we would like. For one thing, the angle at which you hold the bottle is extremely important, and no one gives instructions about this. There’s also foam, and pressure, and temperature, and… you get the picture.
Fortunately, the amount of drug delivered depends, most of all, on the volume of solution that can be held in the little pocket between the eyeball and the lower lid–and that’s usually less than a drop.
If a stream comes out, then you squeezed too hard.
Yep, just like a zit.
Judging from the fact that the “wettability” factor in your eye probably couldn’t be any greater, my uninformed guess would be that simple contact (a fluid sweep) across your eye would happen (and according to the manufacturer - be sufficient!) regardless of if you apply one drop or two. Since one will work, conserve your med.
Thanks, Nametag, for the serious answer.
Violet and lieu; 
Actually my doctor demonstrated exactly how to administer the drops. She’s quite young and very professional. I like her.
Peace,
mangeorge
Well, with an occasional severe hangover, I can state that when my hands shake, it’s pretty obivous I’m getting a “light” dosage. The drop wouldn’t haven’t dripped without severe agitation.
grrr this being one of those moments… obivous=obvious
Back in my lab days, there were products that used drops as measurements. I forget how much volume they were supposed to be, but it was consistantly close enough to use with pipetted volumes.
PC