Why do bacteria-like floating objects appear in front of your eyes when you look at things?

More than three hundred years ago, the Dutchman Antonie van Leeuwenhoek first saw and described the morphology of bacteria under a microscope. Since then, this oldest and most numerous tiny life form on earth has officially entered the visible range of humans.

Visible bacteria

Source: viki

However, when many people look up at the sky, they also see many strips or dots that look like bacteria. Could it be that our eyes have become microscopes, and everyone can see bacteria with their naked eyes?

In fact, these things are not bacteria, but turbidity floating in the vitreous body of our eyes. What is the vitreous body? Where do the floating objects in it come from?

Today, I will talk to you about the vitreous body that allows us to see "bacteria" with our naked eyes.

1. The “transparency” that is easily overlooked

When talking about the components of the eyeball, what comes to your mind first? Is it the cornea, which has been very successful in the field of organ transplantation in recent years, or the lens, which is the focus of cataract surgery, or the retina, whose imaging accuracy has not yet been matched by artificial products...

Cross-section of an isolated eyeball

Source: Ophthalmology

Although these structures are familiar to us in our daily lives, the largest component of our eyes is rarely mentioned: the vitreous body. Even in professional eye examinations, the vitreous body is often ignored as a refractive medium.

In fact, the vitreous body is a jelly-like substance that fills the entire eye, with a volume of up to 4.5 ml, accounting for 4/5 of the total volume of the eyeball. In an eyeball that is known for its precision and compactness, such a volume is already a well-deserved "giant".

Human vitreous specimens

Source | Sebag, Jerry. (2008). Vitreoschisis. Graefe's archive for clinical and experimental ophthalmology

So, what exactly is this "transparency" that has no sense of existence?

As a component of the eye's refractive medium, the normal vitreous body is a colorless, transparent colloid that contains 98% water and 0.15% macromolecules, such as collagen, hyaluronic acid and soluble proteins. The remaining solid matter includes various ions and low molecular weight substances, which make the vitreous body in a gel state with a texture similar to jelly.

Therefore, the vitreous body has good plasticity, viscoelasticity and anti-compression properties, and can support and reduce shock to the lens, retina and other surrounding tissues in the eyeball. In addition, the vitreous body is also a reservoir for nutrients and metabolites in the eyeball.

It can be seen that although it is easy to be overlooked, this "big transparency" plays a very important role in our eyes.

2. Why does the vitreous body become cloudy?

So why do impurities appear in the originally transparent vitreous body and make it cloudy? In fact, most vitreous opacities are an age-related change .

Source: Ophthalmology

The vitreous body metabolizes slowly and cannot regenerate. The vitreous body is in a gelatinous state when a person is born. At about the age of 4, the gelatinous vitreous body begins to gradually dehydrate and shrink. The hyaluronic acid is gradually consumed and dissolved, the stability of the collagen is destroyed, and the water and collagen are separated to form a liquefied cavity in the vitreous body. This process is called vitreous liquefaction .

By the age of 14-18, about 20% of the volume of the vitreous cavity, which was originally filled with gelatinous vitreous, is liquid. With age, the vitreous structure of the liquefied part disintegrates, the original collagen network structure collapses, and colorless and transparent collagen fibers of varying shapes are formed around the liquefied cavity.

In a bright environment, when light passes through the turbid vitreous body, "bacteria" of various shapes and numbers will appear in the field of vision.

Source: pexels

In addition to normal physiological changes, intraocular inflammation, vitreous blood accumulation, elongated eye axis and other factors can cause vitreous opacities.

3. How to sterilize our vision

Generally speaking, the occasional "bacteria" in front of our eyes will not affect our normal life. Physiological vitreous opacities only require regular fundus examinations to be alert to the formation of retinal holes. If you feel that your life is affected, you can take drugs that promote microvascular dilation and blood circulation under the guidance of a specialist to improve related symptoms.

In addition, using lasers to blast the opacities in the vitreous into tiny particles, promoting their absorption into the eye , also helps eliminate the discomfort symptoms caused by vitreous opacities.

Source: unsplash

Pathological vitreous opacities caused by factors such as intraocular inflammation or blood accumulation in the vitreous have a greater impact on normal life, and the primary disease may also cause retinal tears and retinal detachment, which often require surgical removal of all or part of the vitreous for treatment. It should be noted that after vitrectomy, the patient's lens will lack the vitreous to help it obtain nutrients and excrete metabolites, which will eventually lead to cataracts.

It turns out that the reason why we can see "bacteria" with our naked eyes is thanks to this unknown "transparency" in the eyes. Although most vitreous opacities do not require special treatment and we don't need to panic about it, we should still protect our eyes as much as possible in our daily lives and stay away from the risk factors that cause pathological vitreous opacities. After all, once this "transparency" has problems, it will also bring very serious consequences!