When one eye is injured, why can the other be blinded?

The whole frightened Yi Dujun | Jia Ning

The human body is truly a “precision instrument”.

Nervous system, bones, muscles, various cells, etc., the structure and function are closely matched, and together maintain the normal operation of various functions of the human body.

Take our body’s immune system as an example.

The human immune system has three layers of defense:

Immune organs such as bone marrow, spleen, lymph nodes, tonsils, etc.;

Immune cells, such as lymphocytes, mononuclear phagocytes, neutrophils, etc.;

Immunologically active substances, such as antibodies, lysozyme, immunoglobulins, interferons, etc.

The three-layer structure complements each other and cooperates to identify and eliminate antigenic foreign bodies in the human body, and maintain the balance and health of the body.

The human immune system works very strictly, but if you think that it does not leave dead ends, you will be misunderstood. It actually has a lot of “bugs” that you can’t figure out, for example:

It doesn’t even know you have eyes.

At the same time, I also advise you to let it find out that you have eyes.

The Immune System: Don’t Move It

The immune system of the human body really has many “dead spots”, which are called “immune forgiveness effect”.

Immune amnesty is a common process of anatomy, physiology, and immune regulation that limits the immune system’s recognition of foreign molecules, deviates the nature of the immune response from harmful inflammatory responses, and suppresses immunity Mediates inflammatory expression in immune-pardoning organs.

Simply put, in the immune forgiveness zone, the body will not reject foreign invading antigenic proteins, and the relevant parts will not become inflamed.

If there is a word to describe the nature of immune forgiveness more vividly, it is probably that immune cells have done it to foreign invaders – “see no evil, speak no evil, do not act against evil”.

Many parts of the human body have varying degrees of immune amnesty, such as the eyes, brain, pregnant uterus, placenta, liver, hair follicles, cartilage, testes, prostate, etc.

Among them, the eye is the first organ to be found to have immune forgiveness effect, and it is also one of the organs with the most mature effect.

Image source: Figure Worm Creative

Over 180 years ago, Dutch ophthalmologist van Dooremaal transplanted mouse skin into the anterior chamber of dogs and found that it could survive in the anterior chamber for a long time;

In the 1940s, researcher Medawar also found a similar situation, implanted in the anterior chamber of the graft can survive for a longer period of time, he believes that this is a kind of “immune neglect”;

30 years later, scholars Kaplan and Streilein found through observation that after injecting allogeneic lymphocytes into the anterior chamber of the rat, a non-classical immune response occurred, which made the rat not immune to Invading antigens are rejected.

In this way, the immune-pardoning effect of the eye was discovered.

Many doctors and scholars have tried various methods to find out why there is an immune amnesty effect in the eye.

In the 1940s, researcher Medawar believed that the immune-pardoning effect of the eye was due to the lack of a lymphatic system in the eye tissue, which prevented antigens from reaching the regional lymph nodes, allowing these invaders to penetrate the immune system. the void.

However, based on current research, the above conclusions are somewhat untenable. Although there is no definitive theory yet, many studies have found that the immune amnesty effect of the eye is not actually due to the neglect of the immune system, but is actively promoted by multiple systems and cells under its regulation.

One ​​way of saying that antigens invading the eye usually do not generate red flags that lead to immune-mediated validation, but instead elicits “anterior chamber-associated immune deviation (ACAID),” a type of deviation A systemic immune response that suppresses immune-mediated inflammation. In other non-immunely pardoned parts of the body, antigens transmit danger signals to the immune system, triggering an inflammatory response.

Current evidence suggests that ACAID is a central mechanism of ocular immune amnesty.

In addition, inflammatory lymphocytes invading the eye are induced to undergo apoptosis by Fas and FasL molecules expressed on cells of the cornea, iris ciliary body and retina.

Some people may ask, in this way, the eyes are actually a “blind spot” of human immunity, isn’t this a problem?

Actually, the immune-pardoning effect of the eye does have pros and cons.

On the one hand, because of the amnesty effect, orthotopic keratoplasty has the highest success rate among all organ transplants; on the other hand, ocular herpetic stromal keratitis is a In immune-mediated diseases, healthy eyes induce an ACAID response to viral infection and avoid inflammation of the corneal tissue.

However, anotherAspects of immune amnesty do have time to delay things.

If a tumor grows in the human eye, the immune cells (T cells) will not be activated to fight the tumor due to the amnesty effect, which will eventually lead to the unrestricted growth of the tumor in the eye, resulting in serious consequences.

Such as Retinoblastoma | Figure Worm Ideas

Immunological forgiveness has two sides, but its existence is necessary. Otherwise, once your eyes are discovered by the immune system, it will be miserable.

Please hide your eyes

Under normal circumstances, the human immune system is unaware of the presence of the eye. Eyes and immune cells do not disturb each other and live in peace in the pardon zone.

But when the eye is injured due to sharp objects, explosions, etc., penetrating the eyeball; or due to surgical trauma, such as iridectomy, removal of eye contents, keratectomy… Various reasons When the lens ruptures, the lens proteins have the opportunity to flow into the bloodstream and become antigens, and the immune system immediately finds out: Oh, so you have eyes.

The existence of the eye is discovered by the body, what happens next?

Find one eye, implicate another. Whether the eye is injured or not, it will be attacked indiscriminately.

This condition is medically called “sympathetic ophthalmia.”

Sympathetic ophthalmia is a bilateral non-necrotizing granulomatous uveitis caused by perforation of the eyeball or intraocular surgery in one eye. It is essentially an autoimmune-mediated eye disease. Internal inflammation.

It is generally accepted that sympathetic ophthalmia occurs when penetrating trauma to one eye triggers an immune response against uveal autoantigens. Of these, the injured or operated eye is called the irritant eye, and the other eye is called the sympathetic eye.

What happens to the uninjured sympathetic eye after sympathetic ophthalmia?

Although most of the eyeballs of the sympathetic eye are intact and healthy, thanks to the stimulation of the eye, the lens protein contained in the human eyeball has been recognized by the immune system, and the immune cells will follow the “genetic memory” , attacks the healthy eye.

Sympathetic ophthalmia usually develops unconsciously, with symptoms such as mild pain and shame. Conditions such as cataracts, secondary glaucoma, macular edema, and exudative retinal detachment may also be present.

Moreover, one of the major features of sympathetic ophthalmia is that the repeated inflammation worsens, resulting in decreased vision in the sympathetic eye, and even blindness in severe cases.

Image source: Reference [9]

What’s even scarier is that even after many years have passed, the immune system can find your eye and kill it.

Statistics suggest that the time interval between eye trauma and the onset of sympathetic ophthalmia varies widely, ranging from days to decades.

In general, 65% of patients with sympathetic ophthalmia develop 2 weeks to 2 months after eye injury; 70% occur within 3 months and 90% occur within 1 year within. According to literature records, the earliest cases with complete clinical and histopathological data had an onset interval of 10.5 days, and the longest interval even reached 50 years.

Henan Xinmi Eye Hospital once received a patient who developed sympathetic ophthalmia 26 years after eye trauma.

Image source: Reference [10]

Therefore, in order to avoid irreversible consequences of the sympathetic eye after trauma or surgical injury to one eyeball, sometimes the affected eyeball has to be removed.

Everyone must pay attention to safety in life and stay away from risk factors that can lead to eye trauma. Hide your eyes and don’t let the immune system find them.


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