You have pathologically abnormally long eyes. This is called "Pathologic High Myopia" that puts you at much higher risk of retina tears and detachments, glaucoma and macular degeneration. Most people with that much myopia have lattice which are thin areas of the retina. These areas may or may not have holes. If there are round holes they may or may not need to be treated with laser or freezing (Cryotherapy) for prophylactic treatment to prevent a RD. There are many factors that will cause good Eye MDs to disagree which need treatment: size, number, location, family/personal history, occupation. Horseshoe tears (HST) are much more ominous as they have, be definition vitreous traction on them. Most surgeons would treat a HST in your case. The question mark means the first surgeon was not sure it was a HST. The second did not see a HST. PVD causes flashes. They should subside and get better over the coming weeks. If you have sudden increase of new floaters, sudden increase of flashes, sudden loss of peripheral or central vision you need to immedaitely see on of the retina Eye MDs.