The trabecular meshwork in the drainage angle in your eye has nothing
to do with your tear ducts.  The eye has two plumbing systems, one
inside and one outside.  The outer system involves the lacrimal gland,
the gland that makes tears, and the lacrimal drainage system, the
"tear ducts" that drain into your nose (that's why we sniffle when we
cry).  The internal plumbing system is what is involved frequently in
glaucoma patients.  This involves the production of aqueous fluid by
the ciliary glands behind the iris.  Fluid moves in through the pupil
and drains where the iris meets the cornea in the front of the eye, in
the "angle" that filters fluid through the trabecular meshwork.  In
most folks, the angle is 30-40 degrees open, but if fluid can get TO
the meshwork, it can't get THROUGH it, and that raises eye pressure
gradually.  That's primary open angle glaucoma.
    In a small percentage of people, the drain is less than 10
degrees open.  This is congenital and is often seen in people with
very small eyes (farsighted individuals) with crowded tissues inside
the front of the eye.  As these people get older and the lens in the
eye becomes more of a cataract and thickens with time, the iris is
further pushed forward and the angle closes off even more.  Where the
iris touches the lens, a ball-valve effect is created which partially
obstructs aqueous flow to the angle.  This may cause the iris to bulge
forward and close off the angle permanently.  This can occur slowly
(chronic angle closure) or quickly (acute angle closure), which is
painful and can cause very rapid visual loss (over a day or two) if
not corrected.  A laser iridotomy allows fluid to equilibrate on both
sides of the iris and bypasses the pupil to allow aqueous a more
direct access to the drain.  Even so, the drain itself may still not
function perfectly even if an iridotomy is performed and the angle
deepens (many call this "mixed-mechanism" glaucoma--it has aspects of
both narrow and open angle glaucoma)...after an iridotomy, treatment
is more or less the same, with topical drops to lower IOP.  Hope that
answers some questions.
--Rick Cohn, MD
Glaucoma Specialist
Winter Park, FL