Glaucoma: Understanding the Causes, Symptoms, Treatments & More

Glaucoma is a common eye condition where the optic nerve, which connects the eye to the brain, becomes damaged. Many forms of glaucoma have no warning signs. The effect is so gradual that you may not notice a change in vision until the condition is at an advanced stage. Therefore, it is also called a ‘thief of sight.’ In Hong Kong, glaucoma is the leading cause of blindness (23%).

What Is Glaucoma?

Glaucoma is a disease related to our optic nerve's damage (connected eyes and brain) and retinal nerve fibre layer (intrinsically photosensitive retinal ganglion cells). When intraocular pressure increases abnormally, it damages the eye and causes reduced vision and then blindness which cannot be reversed.

Understand the Eyeball Structure

The anterior chamber is the aqueous humour-filled space inside the eye between the iris and the cornea. The fluid in the anterior chamber is used for nutrient supply for our eyes and metabolite output. 

High intraocular pressure causes glaucoma. The fluid inside your eye, called aqueous humour, usually flows out of your eye through a mesh-like channel. If this channel gets blocked, or the eye is producing too much fluid, the liquid builds up and raises the intraocular pressure, causing glaucoma over time.

Types of Glaucoma

There are two types of glaucoma, namely primary and secondary glaucomas. For primary glaucomas, it can be further categorised as open-angle glaucoma, angle-closure glaucoma and normal-tension glaucoma.

1. Open-Angle Glaucoma

   It is the most common type of glaucoma. If the fluid in your eye can’t drain fast enough, it creates pressure that pushes on a nerve in the back of your eye (the optic nerve).  Many people don’t have any symptoms until they start to lose their vision, and people may not notice vision loss right away.
   
   

2. Angle-Closure Glaucoma

   In this type of glaucoma, the outer edge of the iris blocks fluid from draining out of the front of the eye. The fluid builds up quickly, causing a sudden increase in eye pressure.
   
   

3. Normal-Tension Glaucoma

   It is a type of open-angle glaucoma that happens in people with normal eye pressure. Experts don’t know what causes normal-tension glaucoma, but it is believed that the causes are related to intraocular pressure and other vascular diseases.
   
   

4. Secondary Glaucoma

   Secondary glaucoma is caused by other medical conditions that increase intraocular pressure, such as cataract, diabetes, uveitis, eye injury, intraocular bleeding, tumours and post-surgery complications.

Symptoms of Glaucoma

The symptoms of early-stage glaucoma are not obvious and hard to notice for many patients. If you observe the following symptoms, you may have acute glaucoma and should seek medical advice as soon as possible.

• Severe eye ache
• Nausea and vomiting
• Eye redness
• Sudden blurred vision
• Halos around lights
• Jerky eye
• Headache

If you lose your peripheral vision, your optic nerve is severely damaged, and vision loss is irreversible.

Risk Factors of Glaucoma

According to the World Health Organisation, glaucoma is the second leading cause of blindness globally. The risk factors include:

• Age: People aged over 60 years old are prone to glaucoma.
• Race: Asians have a higher risk of glaucoma. According to the CUHK Eye Centre, one-fourth of 60 million glaucoma cases in the world are ethnic Chinese. There are 120 thousand glaucoma patients in Hong Kong.
• Other eye diseases: Chronic eye inflammation, thin cornea and eye injuries (such as bruise) could raise intraocular pressure.
• Family history: Individuals with a family history of glaucoma increase the risk of this eye disease.
• Medical history: People with diabetes, high blood pressure and cardiovascular diseases have a higher risk of glaucoma.
• Medication: Those taking certain steroid medications such as prednisone have a higher chance of having secondary glaucoma.

Diagnosis of Glaucoma

Your doctor will review your medical history and conduct a comprehensive eye examination. Your doctor may perform several tests, such as measuring intraocular pressure, testing for optic nerve damage with a dilated eye examination and imaging tests, checking for vision loss areas, measuring corneal thickness and inspecting the drainage angle.

It is important to have regular eye tests so that glaucoma can be diagnosed and treated as early as possible.  If you are at a higher risk of glaucoma (those with over 6 diopters or a family history of glaucoma), you may be advised to have more frequent and thorough tests.

Below are the glaucoma examination fees of local hospitals and optical centres for your reference.

Hospitals / Optical Centres	Glaucoma Examination Fees (HKD)*
Hong Kong Sanatorium & Hospital	$790 – $1,720
LensCrafters	$700 – $1,500
The Optometry Clinic at PolyU	$2,000 – $2,300
The Department of Ophthalmology & Visual Sciences of the Chinese University of Hong Kong	$3,930 – $4,830

*Prices as of 16 March 2021

Treatments of Glaucoma

Treatments of glaucoma are numerous, including medications, laser therapies and surgeries. Doctor Leung Yu Lung, an Ophthalmology specialist from Hong Kong Sanatorium & Hospital,  explained that laser treatments and eye drops could help most glaucoma patients (around 90%) lower their intraocular pressure, and only 10% of cases require further surgeries.

Glaucoma surgeries lower the intraocular pressure by draining away the extra fluid and controlling its accumulation in your eyeball. Below are the common types of glaucoma surgeries.

Surgeries	Procedures	Risks	Fees for Reference*
Trabeculectomy	A piece of the iris is removed to make a plug inside your eyeball and allow extra fluid to drain away.	Recurrence of intraocular fluid secretion and outflow imbalance in eye Development of cataract or deterioration of pre-existing cataract	$10,000 - $14,000 per eye
Glaucoma Drainage Implant Surgery	In this procedure, your eye surgeon inserts a small tube shunt in your eye to drain away excess fluid to lower your eye pressure.	Exposure of implant and bacterial infection	N/A
Laser Therapy or CryoTherapy	To decrease the production of fluid inside the eye, the procedure usually involved the use of laser or cryotherapy to destroy the tissue producing the fluid.	Bleeding in the eye, chronic inflammation and swelling	N/A
Lens Extraction Surgery	This cataract surgery can be used to treat glaucoma as well. Your doctor will make a very tiny incision on the edge of your cornea to remove the cloudy lens from the eye and then implant the intraocular lens.	Posterior capsule opacification and thus blurry vision may occur after the surgery. Laser therapy could help improve your vision rapidly.	$23,800 per eye

Sources: The CUHK Eye Centre

*With reference to the charges of the HKSH Ophthalmology Centre; prices as of 16 March 2021

Can Glaucoma Be Cured?

The nerve cell damage and vision loss caused by glaucoma cannot be reversed, but treatments and regular checkups can help slow or prevent vision loss, especially if you catch the disease in its early stages.

Prevention Tips for Glaucoma

The key to prevent glaucoma is preserving our eyes. The factors to avoid the increase of intraocular pressure Protecting your vision is the key to prevent glaucoma. To avoid increasing your intraocular pressure, please see the good practices below.

1. “20-20-20”: Look away from your screen every 20 minutes to a distant object at least 20 feet (6 m) away, for at least 20 seconds.
   Extended Reading: Computer Vision Syndrome & Dry Eye Syndrome: What are the Symptoms and Treatment?
   
   
2. Consume antioxidant food such as blueberry and prune
   Extended Reading：Having a Healthy Diet
   
   
3. Sleep for 8 Hours
   Extended Reading: The 24-Hour Society
   
   
4. Don’t or quit smoking
   Extended Reading: Snuffing Out Smoking

---

Vision is precious, and in no way should we abandon the gift of sight. Cigna DIY Health Plan enables you to freely choose from various protection benefits to customise your plan to your individual needs, including dental coverage, regular oral check-up, treatment cost and emergency. Tailor your health coverage now.

Sources:

1. 青光眼
2. 青光眼藥物
3. 青光眼隨時偷走視力致盲 及早控制眼壓 藥物、手術治療方法多
4. 小心青光眼隨時來襲！
5. Glaucoma is second leading cause of blindness globally
6. 擊退致盲眼疾- 青光眼（上）