Expert Science Popularization | Why are there "mosquitoes" flying in front of me? Patient | Flying Mosquito Syndrome | Mosquito

In the scorching heat, mosquitoes and insects begin to become active. Ophthalmology also has a disease where patients often feel that there are black shadows or unknown objects flying around in front of them, like mosquitoes, but they can see but cannot touch them. What's going on here? If you have a similar experience, then you may have vitreous opacity, commonly known as "mosquito fly syndrome". "Flying Mosquito" is a concrete term, manifested as small black shadows or opaque objects floating in front of the eyes, which can move with the rotation of the eyes, especially when looking at a bright white background, and may be accompanied by a sense of flash.

From ancient times to the present, countless people have been troubled by "flying mosquito disease". During his youth, the literary giant Bai Juyi once wrote "Two Poems on Eye Diseases", in which he wrote: "A thousand pieces of snow scattered in the air, a heavy veil draped over a cage. Even in clear scenery, one can see mist, and flowers even in spring." In the "Yu Yuan Jiu Shu", it is also said: "Those who are like flies hanging in their eyes, move tens of thousands, and are covered with the result of hard study and literature." From the perspective of modern medicine, this symptom should be due to eye diseases including myopia and severe vitreous opacity. At present, the incidence rate of vitreous opacity in China is 20% -30%. Most vitreous opacity is a physiological change that does not affect visual function. However, it may also be a clinical manifestation of certain eye diseases and needs to be taken seriously.

Where does the annoying "flying mosquito" come from?

Eyes are often compared to cameras. The cornea, aqueous humor, lens, and vitreous body of the eye are like "lenses", while the retina is like "film". When taking photos, light passes through the lens and focuses on the film, forming a clear photo. If any component of the eye lens becomes dirty, the photo will have dirty spots or become blurry. And the appearance of "flying mosquito syndrome" is precisely because the vitreous body has become cloudy.

The vitreous body is in a transparent gel like state, mainly composed of water, hyaluronic acid, and a fine network of collagen fibers. As one ages, the vitreous body ages and water separates from collagen. Collagen fibers gradually contract into opaque point like, linear, or clustered aggregates that can float in the liquefied vitreous body. These opaque objects block the light and cast shadows on the retina behind them, creating a feeling similar to "mosquito dancing". Although it may affect visual effects, pure vitreous opacity does not affect visual function. However, some eye diseases, such as retinal tears, detachment, bleeding, or inflammation, can also cause symptoms of "flying mosquitoes" due to the obstruction of the retina, bleeding, or inflammatory cells.

Image caption Schematic of "floaters" formation

How to determine whether "flying mosquitoes" are "good" or "evil"?

According to the etiology, "fly mosquito syndrome" can be divided into two categories: physiological and pathological. The vast majority of patients belong to physiological "fly mosquito syndrome", which means that these patients do not have organic lesions in the fundus. It often occurs in middle-aged and elderly people, highly myopic patients, and those with severe eye use. Patients with physiological "fly mosquito syndrome" have a relatively small amount of floating debris in their eyes, which generally does not undergo significant changes and does not affect vision. Pathological "flying mosquito syndrome" often indicates that patients have serious retinal diseases, such as retinal tears, retinal detachment, vitreous hemorrhage, or uveitis. These patients have an increasing amount of floating objects in front of their eyes in a short period of time, which may result in abnormal flashes, obstructed vision, distorted vision, or significant visual impairment. If not treated promptly, visual function may be severely damaged and should be taken seriously.

When seeking medical treatment in a hospital, patients often need to undergo the following tests to determine whether the "flying mosquito" is coming from a bad source:

① visual examination, help to determine the impact of "floaters" on vision;

② eye B ultrasound, can help clear the degree of vitreous opacity, whether there is blood accumulation, inflammation, retinal detachment, etc;

③ Fundus examination, including ophthalmoscope or slit lamp anterior endoscopy, fundus photography and optical coherence tomography, is helpful to find the fundus lesions.

Physiological "fly mosquito syndrome" patients generally have no obvious abnormalities, while pathological "fly mosquito syndrome" patients can preliminarily determine the cause through fundus examination.

How to defeat the "flying mosquito" in your eyes?

Physiological "fly mosquito syndrome" generally does not affect vision and daily life. If the examination confirms that there are no other organic lesions in the eyes, there is no need to worry excessively. Patients can gradually adapt to the presence of "flying mosquitoes" by shifting their attention. At the same time, it is important to maintain good daily routines and eye habits, ensure adequate sleep, and reduce eye strain. Patients with obvious symptoms can try drugs that nourish the eyes and promote eye circulation, such as lutein and iodine containing preparations, to help absorb cloudy substances in the vitreous body. When necessary, laser ablation or vitrectomy can also be used, but these two treatment methods come with surgical and complication risks and require careful evaluation by doctors before implementation. For pathological "fly mosquito syndrome", it is necessary to promptly identify the cause, diagnose and treat the underlying disease, such as laser repair of retinal tears, surgical treatment of retinal detachment, etc.

To summarize, if you find a small black shadow floating in front of you, you can choose to go to the hospital for a detailed ophthalmic examination to rule out possible hidden diseases. If you suddenly notice an increase in dark shadows, a flickering sensation, and a significant decrease in vision in front of you, please immediately seek the help of a professional doctor at the hospital!

Health tips:

Reduce the use time of electronic products and avoid excessive use of eyes;

Ensure adequate sleep, try not to stay up late;

3 balanced diet, eat more rich in iodine, zinc, selenium and other trace elements and vitamin A food;

④ People with high myopia, retinal detachment and other risk factors should have fundus examination every 3 months to half a year.