[ashratnam]

This has been a tough cookie to crack, I mean almost 3 years and no conclusive answer. This answer doesn't do it for me, though.
Isn't closed angle glaucoma a condition in which the iris and the lens sort of 'stick' together, blocking drainage to the anterior chamber altogether? In that case how would giving muscarinic drugs, thereby improving the outflow through the canal of schlem, which is at the angle of the anterior chamber, improve things? Secondly if the lens and the iris are stuck together, what's so wrong with giving an alpha-1 agonist? Won't it just reduce aqueous humour formation and thereby at least buy some time until definitive surgery?
The only real explanation I see is that the resultant mydriasis would, in a sense, 'crumple' up the base of the iris at the angle where the canal of Schlem is, reducing outflow further and increasing pressure in the anterior chamber as well.
…even I'm not convinced by what I just said. Anyone else wish to take a flog at a horse which just refuses to die?

 

[ashratnam]

Ok! I asked an eye surgeon and this is the gist of what he said - Mydriasis in all shapes and forms is contraindicated. There's two reasons - foremost, the state of maximum apposition of the lens and iris is in MID-DILATION, which will result if you dilate a constricted pupil. Secondly, overdilation will indeed cause crumpling of the iris at the angle of the anterior chamber, compromising outflow through the canal of Schlemm.