Anti-Reflective coatings are generally fragile and difficult to keep clean
compared to uncoated lenses. The cheaper coatings will not last long. The
expensive name brand coatings are worth the extra money (Crizal, and others
from major manufacturers). If you get you lens coated at a chain store like
Lenscrafters, you are screwed.

1.  Your fingers are naturally oily.  If you eat and don't wash your
hands afterwards, if you pick your zits and don't wash up afterwards,
if you scratch your headlice and don't wash up afterwards you add more
oil to your fingers.  If you eat a meal at a diner with an open
kitchen and a busy grill the aerosolized grease will deposit on your
lenses.  If you cook at home with oil the aerosolized grease will
deposit on your lenses.

2.  The oil attracts floaters such as dust and dead skin cells, which
degrade viewing through the lenses.

1 combined with 2 make for grubby glasses.  Buy a small square of
microfiber, carry it in a small cloth sack in your pocket.  Use
handwashing liquid at the public lav, use dishwashing liquid at home,
use a bar of soap in the shower if you're pressed for time.

I don't do any of the things listed in #1 except an occasional meal
out and my own cooking.  I clean my glasses at least twice a day,
usually when I'm brushing my teeth in the morning and when I'm washing
up after dinner in the evening.  I can't imagine actively trying to go
more than a day without cleaning my glasses.

Bottom line, get your lenses grease-free and they stay clean longer.

+++++++++++++

Reply to the list as I do not publish an email address to USENET.
This practice has cut my spam by more than 95%.  
Of course, I did have to abandon a perfectly good email account...

A wise optician (of a vanishing breed, I fear) once told me this:

Clean lens surfaces repel water.  If you get them clean by using
soapy fingers to clean them under a running tap, and rinse them
thoroughly, most of the droplets left on the water can be shaken
off, or dabbed away with tissue.

Recently I got a pair of Walgreen's readers that seemed to stay
wet after cleaning.  Well, after four or five cleanings, they were
fine, and shed water like clean eyeglasses should.

Another word of wisdom from the wise optician was "Never,
never, never clean your eyeglasses dry!"

Most people get new frames with new lenses.  That is useful
because guky residues of eyelid defoliate and ugly blinked-out
detritus come to rest in the nose pad supports, and at the
margins of the lenses, under the frames.  Those places are
hard to clean, probably mostly impossible.

Recently ultrasonic cleaners big enough for eyeglasses* have
gotten quite cheap, being now manufactured in China.  Those
will clean lenses and frames, including the inaccessible regions
where guk accumulates, at the same time.  Keeping them
clean with impede corrosion of metal components.

Don't mention to your eye guy that I told you that.  But take
him back your clean lovely old frames when it comes time to
get new lenses.

--
Dicky

_______________
* For instance:  http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=3305

No, you're not imagining it.  I got a pair of glasses with antiglare
coating and found I could never get them clean.  It really drove me to
distraction.  Now, I won't have any coatings put on the glasses.  I
have never found that they do any good anyway and do me far more harm.

Ann