Eye patients, when you notice that your vision has become blurry, the first step is to go to the hospital for an optometry to rule out blurry vision due to refractive problems. Optometry is not simply a check of your vision chart, it is a screening of your vision by a professional optometrist with an optometric instrument. Many times, your doubts or fears are cleared by this one simple examination. When the vision still does not reach normal through refractive examination, a detailed eye examination is required. Then again, your most consulted is a black shadow floating in front of the eyes, the medical term “mosquito flying”. This is a physiological symptom. Most of the time do not stress. A major difference between physiological mosquito flying and pathological vitreous opacity is that the latter affects vision and the dark shadows are obvious regardless of light or dark.