It's amazing how blind one can be and still legally fly. The FAA only
requires that your vision be corrected to 20/40 or better for a 3rd
class medical!
(See the difference between 20/20 and 20/40 he
http://en.wikipedia.org/wiki/Eye_chart )

With a recent pair of glasses, mine never measured worse that 20/30. I
saw my Optometrist regularly and was probably never 20/40 on my worst
day. Still, I left my last flight physical with the impression that I
had come close to failing the eye test. My optometrist is a pilot, one
reason I use him. My specific instructions to him were to tell me when
he would no longer wish to share a pattern with me. He never said those
words, so I never quit flying. Now I'm not so sure I made the right choice.

What's life like at 20/30? Well, I still felt like a perfectly safe
driver, even at night. The main difference was that I had to be closer
to signs to actually read them. But flying is different! You need to
see farther.

My first clue was the TV tower. For many years, that TV tower 5 miles
west of my field represented my personal visibility minimum. If I
couldn't see that tower from the airport, I stayed on the ground, or at
least in the pattern. (Yes, I'm a fair weather pilot.) The trouble was,
my vision had gradually deteriorated to where I couldn't see that tower
even on a severe-clear day. Yet I was still legal to fly.

Also, over a period of a few years, I gradually became used to not
seeing the other planes in the pattern. How did I compensate? First,
by the usual ways. I kept my eyes outside the cockpit, listened closely
to the radio, gave plenty of position reports, confessed when I didn't
"have" the other plane and avoided crowded patterns.

Second, I bought myself a little Zaon MRX. The MRX is a very imperfect
device, but still it beats having no technological help at all. It
beeps when a plane is near. It displays a vague distance, and a
slightly less vague altitude. Unfortunately, it doesn't tell you what
you really want to know, the bearing of the traffic. Still, it serves
at a constant reminder to keep a good lookout.

So that missing tower became my final clue. My vision had deteriorated
below my personal minimum. I saw an optomologist, who diagnosed
cataracts and sent me to an eye surgeon. After one 2-hour trip to the
clinic for each eye to get new lenses implanted inside my eyeballs, I am
now 20/20 again! It's amazing to suddenly have brand new HD vision. My
natural vision had decayed so slowly, over so many years, that I had
forgotten what a human is supposed to see. It's an amazing new world!

My TV tower is back! I can see the other planes in the pattern again!

What does the FAA say about all this? According to the AOPA website,
all I need to do is have my eye doctor fill out FAA Form 8500-7 and
bring it to my next flight physical. Mine is ready and waiting.

So what's my point? If you find yourself in the same boat that I was
in, don't be afraid. Observe your personal minimums. Go boldly to your
optomologist. Your fellow pilots will thank you.