Glaucoma is a disease caused by pressure on the optic nerve due to an increase in intraocular pressure or a disturbance in blood supply. Since the optic nerve has the function of “seeing” by transmitting the light received by the eye to the brain, if there is a disorder in this nerve, a visual field defect appears, and in the final stage, the eyesight is lost. Open-angle glaucoma refers to glaucoma that occurs while the angle of anterior chamber is not compressed and maintains its normal shape. . The angle between the back of the cornea and the front of the iris is called the angle of anterior chamber.
The criteria for classifying glaucoma are diverse, and can be broadly divided into acute and chronic according to symptoms. Acute glaucoma accounts for about 10% of all glaucomas, and as intraocular pressure (the normal range of intraocular pressure is 10 to 21 mmHg) rises rapidly, symptoms such as decreased visual acuity, headache, vomiting, and redness appear.
In chronic glaucoma, the optic nerve is gradually destroyed, so the patient does not feel any special symptoms, but at the end of the narrowing of the field of view, it feels stuffy, and if it progresses further, it leads to blindness.
The main cause of the development of glaucoma is damage to the optic nerve due to increased intraocular pressure. The process of damage to the optic nerve is explained by two mechanisms: that the optic nerve is compressed due to an increase in intraocular pressure, and that the damage to the optic nerve proceeds due to a disturbance in blood flow to the optic nerve. However, the exact cause of the disease is still not known, and research on it is ongoing.
Intraocular pressure refers to the pressure in the eyeball. Just like a soccer ball with neither too little nor too much air in it, to maintain the shape of the eye, proper pressure must be maintained inside the eyeball. If the intraocular pressure is too low, atrophy of the eyeball itself may occur, and if the intraocular pressure is too high, the optic nerve may be damaged. The intraocular pressure is mainly determined by the aqueous humor (the water produced inside the eye, which is responsible for maintaining the shape of the eye and providing nutrients to the inside of the eye).
The aqueous humor is produced little by little every day in the tissue called the ciliary body behind the iris, and it has a flow that is discharged to the outside of the eye through circulation as much as the produced amount. When too much aqueous humor is created or the flow is disturbed and the discharge is reduced, the pressure inside the eye rises. The incidence of glaucoma is also high in people with a family history of glaucoma, high intraocular pressure, hypertension, diabetes, cardiovascular disease, and myopia.
Acute glaucoma is so painful that it is usually diagnosed by visiting the emergency room. On the other hand, chronic glaucoma is often asymptomatic, and when symptoms appear, it is already in the terminal stage, so it is difficult to treat. Therefore, it is very important to detect and treat glaucoma at an early stage through regular intraocular pressure and funduscopy.
Visual acuity, intraocular pressure measurement, angle of anterior chamber test (Van Herick technique), slit lamp test, optic nerve test, and visual field test are performed.
In acute cases, it is important to reduce intraocular pressure quickly to preserve the optic nerve. First, eye drops to lower intraocular pressure are instilled, oral intraocular pressure-lowering drugs are administered, and intravenous administration of hyperosmotic agents is used to rapidly lower intraocular pressure. After the intraocular pressure is lowered, a small hole is made in the iris using a laser to help the circulation and discharge of aqueous humor. After the intraocular pressure is normalized, a visual field test is performed to check for visual field defects.
In chronic cases, intraocular pressure-lowering drugs are instilled to prevent further damage to the optic nerve. If the intraocular pressure does not decrease sufficiently, try increasing the drug dose. Depending on the type of glaucoma, laser treatment may be required, and the treatment method differs depending on the individual condition. Glaucoma surgery can be performed if intraocular pressure is not well controlled even with drugs or laser treatment. In this case, the purpose of surgery is to control the intraocular pressure and not to restore the already damaged optic nerve.
Progress and complications
Acute glaucoma has immediate symptoms, so you need to visit a hospital for diagnosis and treatment.
Since chronic glaucoma progresses slowly and no specific symptoms are felt until the end of the disease, early diagnosis and early treatment are the only ways to prevent blindness due to glaucoma.
The goal of glaucoma treatment is to slow or stop the progression, and the already damaged optic nerve does not get better. Untreated glaucoma progresses slowly, leading to visual field loss and eventually blindness.
Because early detection of glaucoma is more important than special prevention, it is recommended that those over 40 receive an annual examination to confirm whether or not glaucoma is present. Among glaucoma, intraocular pressure is within the normal range (10 to 21 mmHg), but damage to the optic nerve may progress. Therefore, in addition to intraocular pressure, it is necessary to check whether there is a defect in the optic nerve fiber layer through fundus photography.
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