Malpractice could be found from a doctor misdiagnosing a condition (at any point--for example, mistakenly concluding that you did not have glaucoma after having already been treating you); it could also be found from a failure to provide or continue the correct treatment. The issue is what  the "reasonable" well-trained doctor would do; if the reasonable doctor would not have acted like this one did, then you may have a malpractice claim. From what you write, it would be worthwhile to speak with a malpractice attorney about your situation.