What is glaucoma?

25 May 2024
What is glaucoma?

Glaucoma is a group of eye diseases characterized by an increase in internal pressure, which leads to damage to the optic nerve and, if treatment is used, to irreversible vision loss. It is one of the most common causes of blindness in the world.

Types of glaucoma

There are several main types of glaucoma, each of which has its own characteristics and mechanisms of development:
     1. Open-angle glaucoma. Open-angle glaucoma is the most common type of glaucoma. It develops gradually and painlessly, which is why it will be called the "silent thief of sight." With this type of glaucoma, the drainage channel of the eye becomes less efficient over time, which leads to increased internal pressure and damage to the optic nerve.
     2. Angle-closure glaucoma. Angle-closure glaucoma, also known as narrow-angle or acute glaucoma, occurs when the angle between the iris and the cornea is too narrow, making it difficult for the intraocular fluid to drain. This can cause a sudden increase in eye pressure. Symptoms include severe eye pain, headache, nausea, blurred vision and even the appearance of iridescent circles around the light source. This type of glaucoma requires immediate medical attention.
     3. Secondary Glaucoma. Secondary glaucoma develops as a result of other diseases or conditions, such as eye injuries, inflammatory processes, status or as a result of taking certain drugs (for example, corticosteroids). Treatment of secondary glaucoma depends on the underlying cause of the disease.
     4. Congenital glaucoma. Congenital glaucoma is a rare form of glaucoma that occurs in newborns and young children. It occurs as a result of improper development of the drainage system of the eyes during the fetal period. Symptoms include an enlarged eyeball, tearing, sensitivity to light, and clouding of the cornea.

How glaucoma affects vision

Glaucoma affects the vision of expansion, starting with peripheral (side) vision. Many people do not notice the loss of vision in the early stages, the last central star remains the same. However, over time, if the disease is not counted, vision loss extends to the central zone, which leads to complete blindness.

Damage to the optic nerve caused by increased intraocular pressure is irreversible. Therefore, detection and regular monitoring of the condition of the eyes are negative to prevent serious early complications of glaucoma. Treatment includes medication, laser treatments, and surgery to reduce internal pressure and protect the optic nerve from further damage.

Glaucoma is a serious disease that requires constant attention and regular medical monitoring to preserve the heart.

Eye anatomy and mechanism of glaucoma development

The structure of the eye as it relates to glaucoma

The eye is a complex organ with a multi-layered structure, each element of which performs its specific function. To understand glaucoma, it is important to know the structure of the following parts of the eye:
    1. Optic nerve (optic nerve). The optic nerve consists of over a million nerve fibers that transmit visual information from the retina to the brain. Damage to the optic nerve caused by increased intraocular pressure is the main cause of vision loss in glaucoma.
    2. Angle of the anterior chamber. The angle of the anterior chamber is the place where the cornea and the iris meet. In this corner is the drainage system of the eye, which is responsible for the outflow of intraocular fluid (aqueous moisture). Normally, fluid drains from the eye through the trabecular meshwork and Schlemm's canal.
    3. Trabecular mesh. Trabecular mesh is a spongy tissue in the corner of the anterior chamber, through which watery moisture passes into Schlemm's canal and further into the venous system of the eye. This is the main way of drainage of intraocular fluid.

Mechanism of intraocular pressure increase

Glaucoma develops due to a violation of the outflow of intraocular fluid, which leads to an increase in intraocular pressure. The main mechanisms causing the increase in pressure include:
    1. Violation of drainage through the trabecular meshwork. With open-angle glaucoma, the trabecular meshwork gradually loses its ability to effectively pass fluid, which causes its accumulation and increased pressure in the eye.
    2. Blocking of the angle of the anterior chamber. With angle-closure glaucoma, the angle between the iris and the cornea can be too narrow or even completely blocked, which makes it difficult for fluid to flow out and rapidly increases intraocular pressure.
    3. Secondary causes. In secondary glaucoma, increased pressure can be caused by other diseases or conditions, such as inflammatory processes, tumors, injuries, or the use of certain medications.

The role of the optic nerve and blood supply

The optic nerve plays a key role in transmitting visual information to the brain. In glaucoma, increased intraocular pressure damages the nerve fibers of the optic nerve, which leads to their degradation and death. This, in turn, leads to vision loss, starting with the peripheral and gradually moving to the central.

The blood supply to the optic nerve is also an important factor in the development of glaucoma. Insufficient blood supply can further damage nerve fibers, worsening the condition of the optic nerve. Decreased blood flow can be a consequence of increased intraocular pressure, as well as other vascular disorders.

Thus, understanding the anatomy of the eye and the mechanisms of increased intraocular pressure is critically important for the diagnosis, treatment and prevention of glaucoma. Early detection of changes in the drainage system and timely medical intervention can help preserve vision and improve the quality of life of patients with glaucoma.

Risk factors and causes of glaucoma

Glaucoma is a complex eye disease that can develop under the influence of various factors. To reduce the risk of its occurrence, it is important to understand exactly what factors influence the development of this disease.

Age and heredity

    1. Age. The risk of developing glaucoma increases significantly with age. People over the age of 60 are more likely to develop this disease. This is due to a decrease in the efficiency of the drainage system of the eye and an increase in intraocular pressure over the years.
    2. Heredity. Glaucoma can be hereditary. If you have a history of glaucoma in your family, especially among close relatives, your risk of developing the disease increases. This is especially relevant for open-angle glaucoma.

Ethnic factors

Certain ethnic groups are more prone to glaucoma:
    1. African Americans. African Americans have a several times higher risk of developing open-angle glaucoma than other ethnic groups. They also tend to have earlier disease onset and more rapid progression.
    2. Asians. Angle-closure glaucoma is more common in Asians. This is due to the anatomical features of the structure of their eyes, in particular, the narrower angle of the anterior chamber.
    3. Latin America. Representatives of Latin American countries also have an increased risk of developing glaucoma, both open-angle and closed-angle forms.

Associated diseases

    1. Diabetes People. with diabetes have an increased risk of developing glaucoma. Diabetes can cause vascular changes and damage to the optic nerve, which increases intraocular pressure.
    2. Hypertension. High blood pressure (hypertension) is also a risk factor for glaucoma. Impaired blood circulation can damage the optic nerve and impair its function.

Use of certain medications

    1. Corticosteroids. Long-term use of corticosteroid drugs, both in the form of eye drops and systemically (in the form of tablets or injections), can increase the risk of developing glaucoma. This is due to the ability of corticosteroids to increase intraocular pressure.
    2. Antidepressants and anticholinergic drugs. Some antidepressants and anticholinergic drugs can affect intraocular pressure, especially in patients with existing eye diseases or anatomical predisposition to glaucoma.

Thus, glaucoma develops under the influence of various risk factors, including age, heredity, ethnic characteristics, concomitant diseases, and the use of certain medications. Understanding these factors helps to detect the disease in a timely manner and to apply the necessary measures for its prevention and treatment. Regular eye exams, especially for high-risk individuals, are key to maintaining eye health and vision.

Symptoms and signs of glaucoma

Glaucoma is an eye disease that can develop slowly and is often imperceptible to the patient in the early stages. Understanding the symptoms and signs of glaucoma is important for timely detection and treatment of this disease.

Initial symptoms

In the initial stages of glaucoma, symptoms may be minor or even absent. However, some people may notice:
    1. Vision changes
        ◦ Peripheral vision: Glaucoma initially affects the peripheral (side) vision, which can cause narrowing of the field of vision. Patients may notice that they begin to see objects from the sides less.
        ◦ Blurred vision: Vision can sometimes be blurry or blurry, especially in the morning or after being in the dark for a long time.
    2. Pain in the eyes
        ◦ Mild pain or discomfort: Mild pain or pressure in the eyes is possible, which is usually not noticed, but can be the first sign of problems.

Late symptoms and disease progression

If glaucoma is not treated, the disease progresses and the symptoms become more pronounced:
    1. Significant narrowing of the field of vision
        ◦ Tunnel vision: Patients may experience a "tunnel vision" effect where they can only see what is directly in front of them and their peripheral vision is significantly lost.
    2. Severe pain and other signs of angle-closure glaucoma
        ◦ Acute eye pain: Angle-closure glaucoma can cause sudden and severe eye pain.
        ◦ Headache: Often accompanied by a severe headache that may be unilateral.
        ◦ Nausea and vomiting: Severe cases of angle-closure glaucoma may cause nausea and vomiting.
        ◦ Sudden visual impairment: Sudden decrease or loss of vision.
        ◦ Halo around light sources: Patients may see iridescent circles around light sources.

Absence of symptoms in the early stages of the disease

One of the biggest problems with glaucoma is that it often has no obvious symptoms in its early stages. This is especially true of open-angle glaucoma, which develops gradually and may remain imperceptible until the moment when significant damage to the optic nerve has already occurred and part of the vision has been lost.

The importance of regular check-ups

Because of the lack of pronounced symptoms in the early stages, regular eye exams are key to early detection of glaucoma. This is especially true for people at increased risk, such as those over 40, those with a family history of glaucoma, people with diabetes or hypertension, and members of ethnic groups at increased risk for developing glaucoma.

Early diagnosis and timely treatment can significantly slow or even prevent the progression of glaucoma, helping to preserve vision and improve the quality of life of patients.

Diagnosis of glaucoma

The diagnostic process includes several stages that help detect the presence of the disease and determine its stage.

Ophthalmological examination and medical history

    1. Ophthalmological examination
        ◦ The first step in the diagnosis of glaucoma is a complete ophthalmological examination. The doctor examines the eye, assesses the condition of the cornea, iris, lens and other structures of the eye. The examination also includes a visual acuity test and visual field evaluation.
    2. Medical history
        ◦ The doctor takes a detailed medical history of the patient, including family history of glaucoma, previous eye diseases, eye injuries, co-morbidities (eg, diabetes, hypertension), and information about medications that can affect intraocular pressure.

Tonometry (measurement of intraocular pressure)

Tonometry is one of the main methods of diagnosing glaucoma and includes the measurement of intraocular pressure (IOP).
    • Applanation tonometry: The most common method of measuring IOP, which is performed using an applanation tonometer. Anesthetic drops are administered to the patient, and then pressure is measured by lightly pressing on the cornea.
    • Non-contact tonometry: It is performed in a non-contact way using an air stream that compresses the cornea. This is a less accurate method, but is used for rapid screening.

Gonioscopy (estimation of the anterior chamber angle)

Gonioscopy allows the doctor to assess the angle of the anterior chamber of the eye - the place where the cornea meets the iris.
    • Procedure: Using a special gonioscopic lens and a microscope, the doctor examines the angle of the anterior chamber. This helps determine whether the angle is open or closed, which is important for diagnosing the type of glaucoma (open-angle or closed-angle glaucoma).

Assessment of the field of vision and condition of the optic nerve

    1. Evaluation of the field of vision
        ◦ Perimetry: Used to assess the patient's peripheral vision. During the test, the patient fixes his gaze on a central point, and the devices project light signals to different parts of the field of vision. The patient signals when he sees these signals. This test helps detect visual field loss typical of glaucoma.
    2. Assessment of the condition of the optic nerve
        ◦ Ophthalmoscopy: Performed using an ophthalmoscope, which allows the doctor to examine the optic nerve. During this examination, the doctor evaluates the shape, size, and color of the optic disc, and looks for signs of nerve fiber damage.
        ◦ Optical Coherence Tomography (OCT): Used to obtain high-precision images of the optic nerve and retina. OCT can measure the thickness of the nerve fiber layer, which helps detect early signs of damage caused by glaucoma.

The importance of an integrated approach

Comprehensive diagnosis of glaucoma is key to timely detection of the disease and prevention of its progression. Regular eye exams, especially for people at increased risk, help detect glaucoma in its early stages, when treatment can be most effective.

Glaucoma treatment methods

Glaucoma treatment is aimed at reducing intraocular pressure (IOP) to prevent damage to the optic nerve and preserve vision. There are several main methods of treating glaucoma, including medications, lasers, surgery, as well as alternative methods and new research.

Drug treatment

    1. Eye drops
        ◦ Prostaglandins: Latanoprost, travoprost, and bimatoprost help increase the outflow of intraocular fluid, which lowers IOP.
        ◦ Beta blockers: Timolol and betaxolol reduce the production of intraocular fluid.
        ◦ Carbonic anhydrase inhibitors: Dorzolamide and brinzolamide reduce the production of intraocular fluid.
        ◦ Alpha-2 adrenoceptor agonists: Brimonidine reduces fluid production and increases fluid outflow.
        ◦ Cholinergic agents: Pilocarpine increases fluid outflow through the trabecular meshwork.
    2. Systemic drugs
        ◦ In cases where eye drops are not effective enough, systemic medications such as oral carbonic anhydrase inhibitors (acetazolamide) may be used.

Laser treatment

    1. Laser trabeculoplasty
        ◦ Argon laser trabeculoplasty (ALT): The laser beam creates micro-burns in the trabecular meshwork, which improves fluid outflow.
        ◦ Selective laser trabeculoplasty (SLT): A softer laser is used, reducing the risk of tissue damage.
    2. Iridotomy
        ◦ Peripheral laser iridotomy: Performed to treat angle-closure glaucoma. The laser creates a small hole in the iris, which improves fluid outflow and lowers IOP.

Surgical treatment

    1. Trabeculectomy
        ◦ This operation creates a new pathway for the outflow of intraocular fluid from the anterior chamber of the eye under the conjunctiva, which lowers IOP. Trabeculectomy is one of the most effective surgical procedures for the treatment of glaucoma.
    2. Shunt operations
        ◦ Implantation of drainage devices: Special shunts or stents, such as the Ex-Press or Ahmedov valve, are used to help drain fluid from the eye, lowering IOP.

Alternative methods and new research

    1. Microinvasive surgical methods (MIGS)
        ◦ Include minimally invasive procedures such as implantation of microstents (iStent, Hydrus) and gel drains that improve fluid outflow with minimal side effects and quick recovery.
    2. New research
        ◦ Gene therapy: Scientists are investigating the possibility of using gene therapy to treat glaucoma by changing genes that affect the production and outflow of intraocular fluid.
        ◦ Neuroprotective agents: Development of drugs that protect the optic nerve from damage caused by elevated IOP.
        ◦ Drug Delivery Technologies: Research into new drug delivery methods, such as sustained-release drug implants, that provide long-term IOP control without the need for daily drips.
Glaucoma treatment requires an individual approach and regular eye condition monitoring. The combination of medical, laser and surgical treatment, as well as the use of new methods and technologies, allows effective control of IOP and preservation of patients' vision.


Tags: vision, eyes, glaucoma