GLAUCOMA: THE SILENT THIEF OF SIGHT

What is glaucoma?

• Glaucoma is a group of eye diseases that can cause vision loss and blindness by damaging the nerve in the back of your eye called the optic nerve.

• The symptoms can start so slowly that one may not notice them. The only way to find out if you have glaucoma is to get a comprehensive eye exam.

• There’s no cure for glaucoma, but early treatment can often halt the damage and preserve your vision.

What are the types of glaucoma?

• There are 3 main types: open angle glaucoma , closed angle glaucoma, normal tension glaucoma.

• In primary open-angle glaucoma, the drainage angle of the eye is open but does not allow fluid, called aqueous humour, to drain adequately. This results in the eye’s drainage system becoming clogged over time, leading to a slow increase in intraocular pressure.

• In angle closure glaucoma, the iris blocks the drainage angles completely resulting in a sudden increase in intraocular pressure. This sudden spike in eye pressure causes headache, eye pain, loss of vision, seeing halos, nausea and vomiting.

• Normal tension glaucoma (NTG), a form of glaucoma where optic nerve damage occurs even though pressures in the eye are within normal limits. NTG is also known to result from poor blood flow to the optic nerve and is associated with a variety of conditions including migraine, sleep apnea.

What are the symptoms of glaucoma?

• In the early stages, patients with glaucoma do not experience any symptoms.

• Over time, one may slowly lose vision, usually starting with your side (peripheral) vision. But as the disease gets worse, you may start to notice that you can’t see things off to the side anymore. Without treatment, glaucoma can eventually lead to blindness.

Am I at risk for glaucoma?

Anyone can get glaucoma, but some people are at higher risk.

• Population-based studies have revealed that glaucoma is more prevalent in Black and Latinx populations

• Primary angle-closure glaucoma is more prevalent in East Asian populations

• Japanese populations have a substantially higher incidence of normal tension glaucoma

• Family history of glaucoma

• Older age, myopia or long axial length, and high eye pressure were reported as risk factors for POAG

How will my eye doctor check for glaucoma?

• Eye doctors can check for glaucoma as part of a comprehensive dilated eye exam.

• Your eye doctor can examine the angle of your iris with an eye examination called gonioscopy. The doctor examines the angle under a microscope with a special contact lens. Then, your doctor will give you some eye drops to dilate (enlarge) your pupil and check your eyes for glaucoma and other eye problems.

• The examination includes a visual field test to check your peripheral vision.

What’s the treatment for glaucoma?

Laser treatment - To lower your eye pressure, doctors can use lasers to help the fluid drain out of your eye. It’s a simple procedure that your doctor can do in the office.

Medicines - Prescription eye drops are the most common treatment. They lower the pressure in your eye and prevent further damage to your optic nerve.

Surgery - If medicines and laser treatment don’t work, your doctor might suggest surgery. There are several different types of surgery that can help the eye pressure.

What is Selective Laser Trabeculoplasty? (SLT)

• SLT is a laser treatment for open-angle glaucoma that lowers eye pressure. It can be used as initial treatment, instead of eye drop medications, or as additional treatment when medications do not adequately reduce the eye pressure. It is often effective but that effectiveness may wear off after some period of time. It can be repeated but the effect may be reduced with repeat treatment.

• SLT is not a cure for glaucoma but one of many treatments to keep it under control.

How does it work?

• Laser energy is applied to the drainage tissue in the eye. This starts a chemical and biological change in the tissue that results in better drainage of fluid through the drain and out of the eye.

• This eventually results in lowering of eye pressure. It may take 1-3 months for the results to appear.

Will I still need to use glaucoma medications?

• For some patients, the eye pressure can be controlled using laser treatment. Others require additional eye pressure lowering agents and may therefore need to use glaucoma medication as well. Think of the SLT as equivalent to one glaucoma medication.

• Just as some patients will require more than one glaucoma medication to control their eye pressure, some may also require laser plus one or more glaucoma medications. It is important to remember that SLT is not a cure for glaucoma, just as medication and surgery are not. Whatever method is used to treat glaucoma, appropriate follow up and testing with your eye care professional is critical.

by Dr Lisa Tan Sor Earn Consultant Ophthalmologist and Refractive Surgeon