Marjor plot hole

This isn't a major plothole. This is actually a case of nitpicking.

It is true, that had he been blind from birth he would have been blind even with the cataracts removed. But he wasn't born blind, neither in the movie or in real life. As I remember in the movie he loses his sight as a toddler, and in real life he loses his eyesight almost completely at the age of three. This is however an area of research in which we do still not have a complete description of how much experience is needed in order to establish visual consciousness. But probably not much experience is needed, given that new research points towards new borns having visual consciousness. What needs experience is the ability to categorise the world, which Virgil and Shirl Jennings indeed had a lot of problems with, given that higher order neurological processes hadn't been wired properly. The really sad thing is that if had he kept his eyesight, it is still unlikely that he would ever gain significant comprehension of what was happening around him, given that he had missed the window called the critical period in which comprehension of visual stimuli is being made. So it is not necessarily a bad thing that he lost his sight again (though in a slightly different way in real life). The movie has taken the liberty of changing some stuff, but given Virgil circumstances he would still be able to experience visual sensory information, he would however have problems with understanding that sensory information. I must say I enjoyed the movie for what it is (with the exceeption of the sometimes very cheesy dialogue such as: "You can see, but you can't see I'm right here for you", come on!).

The real story reported by Oliver Sacks in the New York Times is here:
http://www.willamette.edu/~mstewart/whatdoesitmean2see.pdf

In the film he lost it at 2 or so years.

That's brought up again at the end when he realizes cotton candy was what he'd remembered as clouds.