CONDITIONS
Glaucoma
Glaucoma: Understanding Eye Pressure and Vision Loss
What is glaucoma?
Glaucoma is a disease affecting the eyes where fluid inside the eyes builds up, leading to excessive pressure that damages optic nerve tissue and results in vision loss. In a normal condition, the eye fluid leaves the eye through the drainage angle, keeping the pressure stable.
The visual loss in the glaucoma usually starts at the periphery of the visual field and gradually affects central vision over time. It may take months to years after nerve damage occurs before symptoms become noticeable. Vision loss due to glaucoma is irreversible.
What causes glaucoma?
Glaucoma refers to a condition that damages the optic nerve that links the eye to the brain. The optic nerve carries signals from the back of the eye to the brain, allowing the individual to see. Nerve damage can result from problems with the fluid in the eye. Sometimes, the pressure inside the eye rises, and the fluid presses hard on the optic nerve, damaging it. Glaucoma can sometimes occur even when the pressure in the eye is normal.
Who is at risk of developing glaucoma?
Factors increasing the risk of glaucoma include:
- Being over age 40.
- Having a family history of glaucoma
- Having diabetes, high blood pressure, and heart disease
- Having refractive errors like farsightedness or nearsightedness
- Physical eye injury
- Using prolonged courses of steroid medications
- People with thinner corneas
- Conditions such as retinal detachment, eye tumors, or eye inflammation
What are the types of glaucoma?
There are various types, but two main ones are
- Open-angle glaucoma occurs when fluid accumulates in the front part of the eye despite the drainage pathways being open.
- Closed-angle glaucoma, or angle-closure glaucoma, arises when the eye’s fluid drainage pathways narrow or close. This leads to rapid fluid pressure buildup, potentially causing eye pain and sudden vision loss.
Different types of open-angle and closed-angle glaucoma can be categorized as either
Primary glaucoma: with an unknown cause
Secondary glaucoma: Triggered by specific eye conditions such as surgery, trauma, medications, or eye diseases.
What are the symptoms of the glaucoma?
Most individuals with glaucoma usually do not notice any symptoms until they begin experiencing vision loss.
Primary open-angle glaucoma may initially present with no symptoms, or individuals may notice peripheral vision loss.
In chronic closed- angle glaucoma, symptoms can include seeing halo-like images around lights or may be asymptomatic.
However, in acute closed- angle glaucoma, symptoms are sudden and severe, including eye pain, nausea, vomiting, headache, watery eyes, blurred vision, and halos around bright lights. Acute closed- angle glaucoma condition is a medical emergency, and immediate treatment is needed to prevent vision loss.
How is glaucoma diagnosed?
Glaucoma is diagnosed through a comprehensive eye examination.
Glaucoma testing includes:
- The patient’s history is used to look for symptoms that the patient is experiencing and if there are any general health issues.
- Visual acuity test (eye charts) to check for vision loss.
- Visual field test to check for changes in peripheral vision.
- Dilated eye examination, the pupil is dilated to allow a close-up exam of the eye’s optic nerve and retina.
- Tonometry to check for pressure in the eye.
- Pachymetry to measure corneal thickness.
- Optic nerve imaging, photographs of the optic nerve are taken to indicate areas of damage.
- Gonioscopy is a procedure involving a specialized lens called a gonioscope to examine the anterior segment of the eye, located between the cornea (the transparent outer layer) and the iris (the colored portion of the eye). It checks the blockages where fluid drains out of the eye.
How is glaucoma treated?
Glaucoma treatment is aimed at reducing pressure in the eye.
Treatment for glaucoma focuses on lowering intraocular pressure. Prescription eye drops are commonly prescribed and often serve as the initial treatment. Systemic medications, laser therapy, or surgical procedures may be necessary in certain instances. There has been no cure for glaucoma, early detection and continued treatment can help preserve vision.
- Medicines: Prescription eye drops which lower the pressure in the eye and prevent damage to the nerve.
- Laser treatment: Laser trabeculoplasty aids in improving the drainage of fluid from the eye. Utilizing a high-energy laser beam stimulates the trabecular meshwork, the structure responsible for draining fluid, to enhance its efficiency. While the outcomes of laser trabeculoplasty may be temporary, there may be a need for repeat procedures.
- Conventional surgery: If eye drops and laser surgery fails to manage eye pressure effectively, a trabeculectomy may be necessary. This microsurgical procedure involves creating a drainage flap to facilitate fluid outflow. Subsequently, fluid can filter into the flap and eventually drain into the vascular system.
- Drainage implants: Drainage valve implant surgery may be an option. A small silicone tube is inserted in the eye to help drain fluid.
- Cataract surgery: Extracting the eye’s natural lens can lower eye pressure in individuals with narrow angles. Narrow angles occur when the iris and cornea are close, potentially obstructing the eye’s drainage channel. By removing the eye’s lens through cataract surgery, additional space is created for fluid to exit the eye, resulting in a potential decrease in eye pressure.
In conclusion, understanding the importance of early detection and management of glaucoma is important for preserving vision and overall eye health. Regular eye exams, especially for individuals over the age of 40 or those with a family history of glaucoma, are crucial for timely diagnosis and treatment. By adhering to treatment plans prescribed by ophthalmologist and maintaining consistent follow-up appointments, individuals can effectively manage glaucoma and minimize the risk of vision loss.
References
- American Optometric Association. Glaucoma. Available from: https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/glaucoma?sso=y. Accessed on 12th April 2024
- Glaucoma. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/glaucoma Accessed on 12th April 2024
- Glaucoma. Available from: https://www.healthdirect.gov.au/glaucoma Accessed on 12th April 2024
- Glaucoma. Available from: https://www.hopkinsmedicine.org/health/conditions-and-diseases/glaucoma Accessed on 12th April 2024
