Function of the conjunctiva | Conjunctiva

Function of the conjunctiva

The conjunctiva acts as a kind of outer protective cover of the eye and contributes to the production of the tear film by secreting its goblet cells. This film is vital for the eye.

Conjunctival clinical presentation

The colour of the conjunctiva can be seen on a closer look. A reddening can be an indication of conjunctivitis (inflammation of the conjunctiva). A yellowish colored conjunctiva is often a first indication of jaundice.

This is caused by increased deposition of blood degradation products. These are no longer red in colour like the blood itself, but have a yellow inherent colour. Anemia can also be detected by a closer look at the conjunctiva.

This is then paler, i.e. whiter than usual. Conjunctivitis (inflammation of the conjunctiva) also has clinical significance. It can develop within the framework of local processes (e.g. foreign bodies in the eye) but also in the case of systemic reactions (e.g. bacterial infection). Allergic rhinoconjunctivitis, better known in the vernacular as hay fever, is also very common.

Diseases of the conjunctiva

In principle, conjunctivitis can be caused by numerous pathogens, but only a few are capable of causing severe acute conjunctivitis in healthy people (Streptococci, Corynebacterium diphteriae, Neisseria, Haemophilus). Staphylococcus aureus, Streptococcus pneumoniae and Haemophilus aegypticus are the most common pathogens of catarrhal conjunctivitis. Infection can occur via numerous pathways: air, gastrointestinal tract and many more.

Typical for an infection with Haemophilus influenzae and Corynebacterium diptheriae is a pronounced swelling of the eyelids. Membranes, on the other hand, are mainly formed during infections with Streptococcus pyogenes and Corynebacterium diphtheriae. The so-called petechial (punctiform) bleedings in the eyelids are caused by infections with Streptococcus pneumoniae and H. influenzae.

When the conjunctiva is inflamed, there is usually no swelling of the lymph nodes or skin involvement. Complications include severe keratitis (inflammation of the cornea) (especially in Corynebacterium diphtheriae, Neisseria, H. aegypticus), sepsis (Corynebacterium diphtheriae, Neisseria, Haemophilus, Pseudomonas), dacryocystitis and scarring. The choice of the appropriate therapy depends on the severity of the disease: A mild conjunctivitis (conjunctivitis) is usually treated with local antibiotics (gentamycin, erythromycin, chloramphenicol, neomycin, gatifloxacin, levofloxacin, ofloxacin, ciprofloxacin, etc.)

in the form of eye drops or antibiotic ointments without a smear and without determining the exact pathogen. In cases of severe conjunctivitis, which is accompanied by swelling of the eyelids, massive secretion, membrane formation and possibly also corneal inflammation (keratitits), the pathogen is determined by smear tests, Gram and Giemsa staining and culture of the pathogens on blood and so-called chocolate agar. At the beginning, when the exact pathogen has not yet been determined, treatment is carried out with highly concentrated antibiotics (gentamycin, ceftazidim 5%) and later the treatment is adapted to the exact resistance of the pathogen present.

If necessary, irrigation or cycloplegia (paralysis of the ciliary muscle, which leads to paralysis of the accommodation of the eye and to mydriasis; e.g. with medication) of the eye is also performed. Symptoms of conjunctivitis: Classic signs indicating conjunctivitis are

  • Burning
  • Itch
  • Slight pain
  • White or yellow secretion
  • Redness
  • Photosensitivity
  • Swelling
  • Papillae (seen by the ophthalmologist with the slit lamp)
  • Taped lids

The causative agent of this conjunctivitis is the aerobic, gram-negative diplococci (N. gonorrhoeae), with preference for the mucous membrane and genital tract. Ideally, the culture is performed at slightly elevated CO2 pressure on so-called chocolate agar or Thayer-Martin medium.

It is important to distinguish between N. gonorrhoeae and N. meningitidis. In adults, infection usually occurs through self-contamination. Gonococcal conjunctivitis can lead to severe keratitis (inflammation of the cornea), possibly also with perforation, sepsis, arthritis and dacroadenitis (inflammation of the lacrimal gland).

In addition to various prophylactic agents, a culture is made to treat the disease itself. Inpatient treatment as well as isolation of the affected persons is recommended. Frequent flushing of the affected eye with isotonic saline solution facilitates healing.

In addition, the antibiotic erythromycin is given for topical application and, parenterally (as an infusion), the antibiotic ceftriaxone, penicillin or spectinomycin for 7 – 14 days. The sexual partner must also be treated in case of a disease with gonococci to prevent a possible ping-pong effect. If the diagnosis is uncertain, chlamydia must also be treated.

A conjunctival cyst is a harmless disease of the eye that occurs relatively frequently and usually does not cause any problems. It is a bulging of the conjunctival surface. It often occurs after inflammation or injury.

Under the sacculation, there is usually an accumulation of serous, i.e. clear and not viscous, fluid of varying degrees. Usually the conjunctival cyst is so small that it does not cause any problems. In some cases, however, the movement of the eyeball may feel strange or difficult and there may be a distinct foreign body sensation.

In this case, an ophthalmological checkup should be carried out in any case. If in doubt, this should be done generally. After the examination by the ophthalmologist, the conjunctival cyst is usually punctured.

This means that it is punctured with a needle and emptied. This is usually done under local anaesthetic and should never be done by the patient himself. This is not a painful process.

Complications are extremely rare. If, however, an inflammation occurs as a result, the doctor should be consulted again in any case. After removal of the conjunctival cyst, however, recurrences often occur.

This means that the conjunctival cyst recurs relatively often and may cause problems again. In this case the doctor can be consulted again. There are many different causes for conjunctival irritation, all of which can cause similar symptoms.

Conjunctivitis is not the same as conjunctivitis. However, conjunctivitis can lead to irritation of the conjunctiva and cause the same symptoms. In the context of a conjunctivitis, an inflammatory reaction occurs, which results in increased blood circulation.

Thus, conjunctival irritation typically results in reddening of the eye, which is accompanied by increased tear secretion. Contrary to an irritation of the cornea, a conjunctival irritation is not painful. There is also no decrease in visual acuity.

Further symptoms may occur, but not in all cases. Here, for example, a foreign body sensation or purulent secretion should be mentioned. Possible causes of conjunctival irritation are a superficial injury, minor infections, an allergy or other systemic diseases.

In this case, a doctor should be consulted for clarification in the event of more frequent or prolonged occurrence. A swollen conjunctiva is also called chemosis in medical terminology. In chemosis, pathological processes lead to an accumulation of fluid, a so-called edema, in and under the conjunctiva, making it look swollen and making it stand out from the layers beneath.

The conjunctival edema can lead to either a milky-white cloudiness or severe redness of the conjunctiva. It also causes pain and possibly a decrease in visual acuity. The cause of a swollen conjunctiva can be an inflammation by bacteria or viruses as well as irritation of the conjunctiva.

This can be caused by superficial damage such as foreign bodies, trauma or even UV radiation as well as allergies. The wearing of contact lenses for too long can also be a cause. If the outflow of blood or lymph in the eye socket is disturbed, the increased pressure can also lead to the development of conjunctival oedema.

This flow disturbance occurs, for example, after a trauma or a tumour. However, these causes are rare. Therapy by the doctor is carried out depending on the cause.

If an inflammation is the cause, it is treated. In the case of allergies, an attempt is made to avoid the trigger. Superficial damage to the conjunctiva can be treated by rest, soft contact lenses or, in severe cases, surgery.

Conjunctival tumours are a rare disease affecting the conjunctiva of the eye. However, unlike other tumours, a conjunctival tumour is usually benign and therefore easy to remove and treat, which means that there is usually no long-term damage and negative effects. Nevertheless, malignant tumours do occur from time to time.

Even a conjunctival cyst can be counted as a conjunctival tumour. Also a strong new formation of vessels in the conjunctiva, a so-called hemangioma, is called a tumour. Although it does not look pretty, it causes hardly any complaints and is easy to treat.

In children this tumour can even disappear by itself. In adults, a hemangioma is surgically removed. Other benign conjunctival tumors are melanosis and the conjunctival nevus.

However, both show a certain risk of degeneration, so they must be checked regularly to prevent damage at an early stage. A conjunctival nevus corresponds to a birthmark located on the eye. Melanosis is caused by too much deposition of dark skin pigment.

Malignant conjunctival tumours are carcinoma and lymphoma. The carcinoma is caused by degenerated epithelial cells, while the lymphoma is caused by cells of the immune system. These do not always manifest themselves in the same way (changed surface, pain, foreign body sensation) and are sometimes detected too late.

The therapy consists of surgical removal in the case of carcinoma and radiation therapy for both tumours. Conjunctival melanoma represents the malignant degeneration of melanosis or a conjunctival nevus. Also due to the frequent controls of the conjunctival nevus or melanosis, the conjunctival melanoma is a rare but nevertheless serious disease and requires early and determined therapy.

The conjunctival melanoma is conspicuous by a dark spot in the area of the conjunctiva, which is usually thickened and protruding. The area surrounding the conjunctival melanoma is often darkened and has a high density of blood vessels. The doctor makes the diagnosis based on a clinical examination and tissue analysis by histology.

A CT or MRI is performed to rule out scattering to the nearby lymph nodes. Also, if the suspicion is well-founded, a metastasis in the rest of the body should be excluded. The treatment consists of surgical removal and subsequent radio- or chemotherapy.

Since the tumour recurs frequently, close follow-up care is recommended. Conjunctival lymphoma is a rare tumour of the human eye. In contrast to most other tumours, conjunctival lymphoma is malignant and requires therapy.

However, the prognosis is good. The conjunctival lymphoma is noticeable by a painless swelling in the area of the conjunctiva. This is usually slightly reddish and is localised on the conjunctiva of the lower eyelid.

It develops from degenerated cells of the immune system and can therefore occur both locally and elsewhere in the body. The therapy should be carried out as early as possible. Due to the different causes and the different place of origin, the therapy can vary greatly.

Radiotherapy, chemotherapy and the therapy with so-called biologicals can be considered. A conjunctival hemorrhage is a relatively common clinical picture, but it is usually harmless. It can have many possible causes and usually does not cause any problems.

A conjunctival hemorrhage is noticeable by a visible red spot on the conjunctiva. The bleeding is not painful and does not cause any visual problems. Only a slight irritation of the conjunctiva occurs sometimes.

It often occurs when the pressure inside the eye or blood vessels increases. This is the case when coughing, sneezing, pressing, vomiting, sports, but also during childbirth and high blood pressure. Excessive rubbing of the eyes can also lead to bleeding.

Conjunctival hemorrhage can also occur frequently with drug anticoagulation. This then largely affects old people. Contact lenses or an injury can also be a possible cause.

A conjunctival hemorrhage will disappear on its own within a few days or even two weeks and does not require any therapy. Only with underlying systemic diseases such as high blood pressure or some metabolic diseases such as diabetes mellitus should therapy be considered. A conjunctival tear is a relatively common clinical picture, which usually does not have serious consequences.

An external mechanical load causes the conjunctiva to be the first to be injured. This becomes noticeable by a foreign body sensation, slight pain and bleeding. It can also lead to increased secretion of tear fluid.

While small conjunctival tears heal themselves, large tears are treated by suturing the wound edges together. If there is an inflammation of the affected area, a doctor should always be consulted.