Dang, I didn't realize I couldn't post an email address. If you do google "Those With Visual Snow, you should be able to find the forums dedicated to this, as well as the survey.
Hello Hulabana, to participate in a survey addressing visual snow and other persistent perception problems please contact ***@****. He is a neurologist and psychiatrist making a study in the topic. He will send you a survey that may help in finding out more about the possible causes in your case (BTW tumours are really rare as a cause of persistent visual snow, other diagnoses are much more frequent) so that you can take these informations with you with your next visit to a doctor at your place.
See a neuro-ophthalmologist. Find one at www.aao.org Use the search feature and read the many postings about visual snow. I don't comment much on visual snow because frankly I have not had patients complain of it nor is there much research on the subject.
JCH III MD