i have been writing to this post for a couple of weeks (20/60 with -11.50
retinoscope). the doctor i have last seen thinks my daughter (almost three)
might have cataracts in both eyes but can not be certain yet. she sees about
20/1500 in the middle but about 20/80 or so at the outer edges of the eye. my
point is i have been doing research and surgery will be almost mandatory if
they think it will get in the way of vision at all. at this point your son
should see at best about 20/60 for his age. if anything hinders him he could
develop amblyopia in that eye. an adult can wait for a little while to it
impairs vision but a child can not. at that age about the only thing that i
know the doctors can do is use the retinoscope to see if the the vision is
getting worse. from what i have read the cataract surgery has a high sucess
rate but there are always risks. i know the doctors told me that if my
daughters lenses were taken out she will be farsighted. go for a second
opinion. they are not 100% sure what is wrong with my daughters eyes but know
the lenses are not right. one doctor says we should probably do surgery and
another says no.some of the people who are on this site are very helpful and
have alot more knowledge than me. they have all been a great help. good luck

My understanding is that cataract isn't too hard to diagnose.  If the
doctor can't see into the eye due to the clouding, then the patient
can't see out of it either.  

Communication will be better, but still not good.  I would ask about
amblyopia.  

I am not a vision professional.  I have had cataract in both eyes, but
as an adult.  My wife has amblyopia and is blind in one eye.

The simplest test you can do would be for you to cover each of his eyes
in turn and watch his reaction. If he protests to you covering his
'good' eye that's a fair indication that the other eye is at least
blurry... but it's not a 100% definitive method.

If two ophthalmologists have said your son has cataract then that's
pretty clear cut. Cataracts aren't difficult for eye doctors to
diagnose. But there's often nothing visible to the casual observer until
the cataract becomes quite mature and dense. The proof that he is losing
vision in one eye is the fact that the cataract is present. The reason
he doesn't show any symptoms is because his other eye is 'covering' for
the cataract eye.

If your son occasionally goes cross eyed then this could be a sign that
his brain is already starting to ignore the eye with the cataract, and
this is a very good reason to have the surgery done. Delaying a few
weeks or even a couple of months mightn't be a big problem, but delaying
a couple of years could potentially be to the detriment of his vision
for his whole life.

Dom