Please help me understand cataract vs glaucoma

I am in my early 70s. I have utmost faith in meyedoc whom I will see
in a couple of weeks. At the last exam, based on my vision complaints
and testing, it was determined that I finally passed the threshold for
cataract surgery and lens implants. We had a thread here on lens
types a while back. I have no problem with having to have this done.
Now, I also suffer from mild (little to no damage) glaucoma/elevated
IOP. The R-eye is the worst in both areas. The last vision field test
was done the same day as the cataract determination. For the first
time, noting a small cluster of 3 "hits" in one area of the printout,
he said he was concerned. We both recognize that a single test does
not a problem make, hence I will see him again in a couple of weeks
for retest.
My question is this: If my eyes are so bad that I require cataract
surgery, how can I be expected to see clearly enough to pass a vision
field test? I had a helluva time (worse than usual) just seeing the
blinking lights. I had planned on having the cataract surgery done in
the spring, but could push it up if "clarifying" that issue, would
permit a better assessment of the glaucoma problem.
Again, I would appreciate your enlightment on this, so I can properly
discuss this with meyedoc when I see him.
TIA
Roy

 

It's true that the presence of cataracts can affect a visual field
result... but generally cataracts will make more or less the whole
visual field 'depressed' (i.e. worse). Glaucomatous visual field defects
have a particular pattern where some areas are more affected than others
and this can still show through when the field as a whole is depressed.
In other words, there are ways of telling whether a poor visual field
result is due to cataracts or glaucoma (or something else).

However what you say is certainly true and if you do go ahead and have
cataract surgery your subsequent visual fields should be a lot more
reliable.

Dom