Glaucoma: A silent threat to vision in people aged 40+

Glaucoma is a silent threat that endangers vision because most patients do not notice any abnormalities until the disease gradually progresses, eventually reaching the final stage. Glaucoma is therefore one of the leading causes of permanent blindness, and vision loss from glaucoma cannot be restored.

Glaucoma does not have a visible shape, nor is there a “stone” forming in the eye. It is caused by a reduction of cells and nerve fibers in the retina, leading to changes in the optic nerve head where retinal nerve fibers converge to transmit visual signals to the brain for processing. This results in changes in the visual field (the width of vision). In the early stage, peripheral vision is lost while central vision remains good, so patients often do not notice. The visual field gradually narrows as the disease progresses and becomes more severe, eventually causing blurred vision and potentially blindness. It may occur with or without elevated intraocular pressure.

Types and symptoms of glaucoma: Glaucoma can be divided into 3 types, as follows:

1. Primary glaucomaThat is, glaucoma that has no cause arising from external factors.
   • Primary open-angle glaucoma isthe most common type of primary glaucoma is divided into high intraocular pressure and normal intraocular pressure types. At present, the exact mechanism is still unknown. The disease course is usually slow, so patients often do not notice abnormalities in the early stage. Most cases are discovered during an examination by an ophthalmologist, and when the disease progresses to a certain level of significant visual field loss, patients will begin to have blurred vision, a narrowed field of vision, or reduced ability to adapt vision in bright and dark environments.
   • Primary angle-closure glaucoma is more common in Asians. It is caused by blockage of aqueous humor drainage at the angle of the eye, leading to increased intraocular pressure. It is divided into acute and chronic types. If it is the acute type, patients often have eye pain and red eye.Blurred visionSeeing halos around lights and may have headache, nausea, and vomiting. This is considered an urgent condition that requires prompt treatment to prevent damage to the optic nerve head. The chronic type is more common; patients may have no symptoms or may have mild eye pain or headache that comes and goes over months or years.
2. Secondary glaucomaCaused by other abnormalities of the eye, such as diabetic retinopathy, hypermature cataract, inflammation inside the eye, tumors and cancer within the eyeball, eye trauma, complications from eye surgery, and long-term use of certain medications such as steroids.
3. Congenital glaucoma and glaucoma in young childrenCaused by abnormalities of the eyes since fetal development, resulting in abnormal drainage of fluid in the eyeball. It may involve only the eyes or be accompanied by other physical abnormalities. Patients often have light sensitivity, eyelid twitching, excessive tearing, or the mother may notice that the child has a larger-than-normal black part of the eye (pupil/iris area) or a cloudy dark part of the eye, etc.

Risk factors for glaucoma

1. High intraocular pressureConsidered the most important risk factor because it is the only risk factor that can be controlled. It has been found that the higher the intraocular pressure, the greater the risk of developing glaucoma and the faster the disease can progress.
2. AgeIncreasing age increases the chance of developing glaucoma. It has been found that primary open-angle glaucoma is more common in people over 40 years old.
3. Underlying diseasesFor example, diabetes, high blood pressure, heart and blood vessel disease, or other conditions that affect blood circulation may cause abnormal blood flow at the optic nerve head, making it easier for cells and optic nerve fibers to die, leading to glaucoma. In addition, systemic diseases that may involve eye inflammation, such as rheumatoid arthritis, if the inflammation is chronic, may also lead to glaucoma.
4. Family historyIf someone in the family has glaucoma, the risk of developing glaucoma increases by 4–5 times.
5. Use of certain medicationsFor example, steroid medications in the form of eye drops, oral tablets, or injections. If used for a long time, they can increase intraocular pressure, raising the risk of glaucoma.
6. Eye injuryOr complications from eye surgery
7. Certain eye diseasesFor example, diabetic retinopathy, inflammation inside the eye, abnormal pigment dispersion syndrome in the eye, or certain types of cataracts, etc.
8. Very severe nearsightedness or farsightednessIt has been found that people with very severe nearsightedness have an increased risk of developing open-angle glaucoma, while people with very severe farsightedness have an even higher risk of developing angle-closure glaucoma.

Diagnosis of glaucoma

Glaucoma can be diagnosed by testing visual acuity, measuring refractive error with a computer, a general eye examination, examination of the optic nerve head, examination of the drainage angle, measurement of intraocular pressure, measurement of corneal thickness, and additional special tests to assess the appearance and function of the optic nerve head, including optic nerve head photography, optic nerve head examination with an optical coherence tomography (OCT) device, and visual field testing with an automated perimetry machine.

Glaucoma treatment

Because vision loss from glaucoma cannot be restored to normal, glaucoma treatment focuses on slowing the progression of the disease as much as possible, to prevent loss of the visual field to a level that affects the patient’s daily life. This can be done by correcting or reducing risk factors that cause the disease and increase its severity.

At present, lowering intraocular pressure by reducing the production and increasing the outflow of aqueous fluid in the eye is the only risk factor modification that can be done effectively. In principle, this can be done in three ways: medications, laser treatment, and surgery. Treatment usually starts with medications, except in some patients who have indications requiring laser treatment, in which case laser can be started immediately. If intraocular pressure cannot be controlled with medications or laser, surgery may be considered to create a drainage pathway for fluid inside the eye to flow into surrounding tissues. The ophthalmologist will choose the most appropriate treatment for each patient based on the type, stage, and severity of the disease, as well as the patient’s cooperation with treatment and the patient’s quality of life.

In addition, in cases of secondary glaucoma, the underlying disease must be treated and the causative conditions should be avoided as well. For example, in glaucoma caused by long-term steroid use, the steroid should be reduced or stopped, or changed to another medication instead. A doctor should always be consulted before using any medication.

Glaucoma is a chronic disease that gradually causes loss of the visual field from the periphery inward, eventually affecting the patient’s daily life and potentially leading to permanent blindness. How fast or slow this occurs depends on the type of glaucoma, the stage at which it is detected, and the effectiveness of treatment. Therefore, the patient’s cooperation with treatment is very important. Patients need regular follow-up examinations and continuous treatment. If treated with medications, patients must use them strictly as prescribed and inform the doctor every time if problems occur or if there are side effects from the medication.

Glaucoma prevention

Since glaucoma cannot be completely cured, the best prevention is an accurate diagnosis from the early stage so that timely treatment can be received and the prognosis is good. This can be done by

1. Having an eye examination byan ophthalmologistonce a year, especially for those over 40 years old or who have risk factors as mentioned above
2. If you have abnormal symptoms such as blurred vision, eye pain, headache, red eyes, or seeing halos around lights, see an ophthalmologist as soon as possible.
3. Do not buy eye drops and use them on your own for a long time. Always consult a doctor whenever there is an abnormality in the eyes.
4. Try to properly manage and control diseases that are causes or risk factors for glaucoma, e.g., patients with diabetes should keep blood sugar levels within the normal range.
5. If you work in a field with a risk of eye injury, you should wear eye protection every time.

Information by Dr. Jiratisarawong Thitikulwanich