This kind of polls/surveys can, indeed, provide us with valuable insights into what complications may occur as well as their real-world implications from the patients' point of view. However, from a statistical perspective, the results may very well scare the hell out of us because of reporting bias.

I cannot really see a way of fixing that problem. All we can do is encourage people to report success stories, but we cannot force anyone. And we have no means of reaching out to all those people who have has successful vitrectomies, but have never been members of this forum, and never will be. If the vitrectomy had been a failure, though, they may very well have showed up on the forum afterwards and reported a horror story. Of course, that's the right thing to do in such cases, and they are very welcome on the forum. The purpose of the forum is about support and advice, after all.

But what I'm trying to say is that we should not really rely on statistics generated from the reports, since it may shed an unfairly sinister light on the chances of success. Of course, all the risks are still valid, but I believe that the doctors' own statistics are generally much more accurate, since they take all cases into account, regardless of the outcome, and regardless of whether the patients turn up on the forum or not. While we have no means of checking whether the doctors' reports are honest, I do believe, and hope, that most doctors are honest enough to provide accurate statistics without tampering with the numbers in hope of attracting more patients and more business.