I completely get that you find the analogy ridiculous (and, btw, I almost certainly agree with you), but I guess the argument I am trying to make is that in the case of lasik, a player is using an artificial procedure or aid to help improve his performance, greater than what his body in its natural state can do.
This is true in the case of improved eyesight. It is true in the case of heightened testosterone levels. It is true in the case of pain-killers (when otherwise, a guy would be too hurt to play).
What makes PEDs (steroids, HGH, etc.) inherently "worse" or "evil" or whatever word you want to use? Is it the health risks involved?
At a certain level, the answer can simply be 'they're being used illegally'. Some parts of the MLB code of ethics don't really have to be based on deep, universal, transcendental truths; they can be based on the laws of the land. On the one hand that's just kicking the can down the road; on the other hand, it's ok if the sport keeps things simple. It's... a sport.
I think Emerson's statement about foolish consistency bears fruit here; to some extent you can classify all manner of things as performance enhancers, from training regimens to icepacks to Advil, right alongside today's PEDs and tomorrow's genetic and nanotechnological enhancements, but does that really mean that we should treat them all the same? Is it helpful to do so? Is it even practicable for baseball to break it all down into proscribed and permitted categories, and to have to monitor so many many more things that a player does and doesn't do, because on some sophist level they can be classified as performance enhancement?
Sure, it isn't all casuist hairsplitting. There are interesting gray areas, like amputee sprinters with artificial limbs, and platelet therapy. And they're the sort of thing that lend themselves to a deep and challenging debate. Remember Lance Armstrong's cancer treatment and ensuing therapy? Some people think that that medical regimen actually enhanced Armstrong, and more, that his doctors knew very well that the approach they were choosing would boost his athletic capacity. You want a meaty slippery slope argument, there it is -- on the one hand if you're the athlete, you know damned well that you don't want MLB bureaucrats dictating what your doctor can do, for reasons that may or may not be sound and ultimately relevant. On the other hand, as an observer of human behavior you also know that there are doctors who would be more than happy to choose 'therapy' treatments with an eye for performance enhancement. To frame this in a baseball context: what if Rocco Baldelli's disorder was completely curable, if he went through some sort of hyperintensive medical treatment along the lines of what Lance Armstrong went through? And Rocco Baldelli comes back and wins a couple Triple Crowns? He tests clean, he has a documented medical reason for every treatment he received, he clearly had a medical condition that needed addressed, but he still hits 50 jacks and doesn't seem too tired at the end of a doubleheader? His condition is rare, so it's not like everyone can exploit it if you let it stand, and Rocco just wants to play ball. But he is now, clearly, a better ballplayer than he ever was. How do you draw the line?
Here's my take: having baseball be the final arbiter on what is right or wrong is a problem. It's fine if baseball redefines the debate and casts a light on key issues, but a) baseball is powerless anyway to say something's fine if it's illegal and b) nobody ought to rightfully trust baseball to make these decisions anyway, it's like letting McDonalds run the FDA. These are issues that have to be ultimately determined by society -- by law. And to me that's where you draw the line. The stuff we're looking at over the last 20 years in baseball that have been problems, like steroids and amphetamines, are handily addressed by the law.
Sometimes things can be simple and that's ok.