Flying mosquitoes is the patient’s visual field patients will appear in front of their eyes black dots, and will fly around with the rotation of the eye, as if flying mosquitoes, its shape has a round, oval, dot, line, etc.. Commonly, when the patient is looking at the blue sky, white walls and other brighter backgrounds, it is easier to find its presence. Femtomegaly often occurs in middle-aged and older people over the age of 40, and is one of the common complications of high myopia. The vitreous body for some reason and produce “cloudy”, and then look at the bright background, the “cloudy” shadow will be reflected in the retina, and with the movement of the eye and move, so you see bugs or threads in front of the eyes such as “Floaters” flying, thus creating a feeling of mosquito flying. This vitreous “cloudy” and the resulting flying mosquitoes both physiological reasons, but also pathological reasons. Therefore, the medical called physiological flying mosquitoes and pathological flying mosquitoes respectively.