The ‘silent thief of sight’
Two decades ago Sabrina Hepburn went to see the eye doctor after something went into her eye.
She came away with a diagnosis she didn’t expect. She had glaucoma, a leading cause of blindness and visual impairment worldwide, and the number one cause of irreversible blindness, often referred to as the “silent thief of sight.”
Going in to the doctor, Hepburn had no signs or symptoms that could have alerted her to a problem.
“I was walking around nice and happy,” she recalled. But she said while she would have eventually found out she had the disease, it may have been years later than when she actually did.
“Unless you’re going to the eye doctor every year, you wouldn’t know,” said Hepburn who is a nurse.
Hepburn is now one of over 60 million people affected by glaucoma.
According to ophthalmologist and glaucoma specialist Dr. Rana Greene, glaucoma is a group of eye conditions which all have in common optic nerve damage – that is damage to the nerve connecting the eye to the brain.
“This damage results in the loss of specialized nerve cells called ganglion cells which currently we do not have the ability to replenish or restore,” said Greene.
“Just as the human body is filled with water, so the eye is filled with water called aqueous humour. The aqueous humour plays an essential role in the health of your eye, providing proteins, electrolytes and glucose to the various parts of the eye. The aqueous humor is continually produced in and drained from the eye, helping to maintain the shape and pressure of the eyeball.”
The doctor said only half of the people with glaucoma are actually aware of it. And that as much as 40 percent of an individual’s vision may be lost due to glaucoma without the individual even noticing.
She said anybody can develop glaucoma, particularly individuals with high eye pressure. Those at risk she said include older people, people with a family history of glaucoma, people of color and diabetics. Other risks she said include nearsightedness (myopia), eye injury and steroid use. Newborns and young children she said, may be affected by congenital glaucoma.
The most common form of glaucoma is primary open angled glaucoma and it occurs as a result of resistance to the flow of aqueous humor in the eye through its normal pathways. Angle closure glaucoma occurs when the normal drainage pathways are actually occluded. In both instances, fluid pressure builds up in the eye resulting in optic nerve damage.
Not only was Hepburn one of the many people walking around not knowing she had glaucoma, it also took her diagnosis for her to learn that she had a history of the disease in her family after she did an investigation.
“I didn’t know glaucoma was in my family until I discovered I had glaucoma and then did my investigation,” said Hepburn. “It was very early, so they just put me on one drop and I was on that for almost 10 years.”
When the drops no longer controlled the glaucoma, Hepburn had trabeculectomy surgery on both her eyes three years ago. They created a false opening in the eye to allow the fluid to drain out. When the fluid is not draining well, the pressure goes up, when the pressure goes up that presses on the optic nerve, and when that optic nerve gets damaged vision is lost. She had surgery about three years ago.
Diagnostic tests for glaucoma
To diagnose glaucoma, during the eye exam, the patient’s vision is recorded and their eye pressure is measured. The eye pressure of a healthy eye is 21 or less. The drainage system may be evaluated using a contact lens. During a dilated eye exam with eye drops, the inside of the eye including the optic nerve will be evaluated. Routine tests for diagnosing and monitoring glaucoma include visual field tests to assess peripheral vision and optical coherence tomography (OCT) to assess for optic nerve damage. Pictures may be taken of the optic nerve. The thickness of the tissue at the front of the eye may also be measured as it may affect the eye pressure reading.
According to Greene, primary open angled glaucoma has no symptoms and is the reason glaucoma screening and regular eye exams are so important. She said people at risk for angle closure glaucoma may also have no symptoms at first. And that in an acute angle closure glaucoma attack, people may experience severe eye pain, blurred vision, headaches, nausea, vomiting and they may see halos around lights.
According to the doctor, the goal of glaucoma treatment today is to lower eye pressure to prevent or halt optic nerve damage which she said may be achieved through medications such as eye drops and surgery inclusive of laser treatments and incisional surgery. But she said early detection is key and may prevent significant vision loss from glaucoma.
Diagnosed at an early stage, Hepburn’s initial treatment included just one drop a day which she did for almost 10 years. When the drops no longer controlled her glaucoma, she underwent a trabeculectomy surgery three years ago on both her eyes. Doctors created a false opening in her eye for the fluid to drain out to relieve the pressure on her optic nerve.
Hepburn said because glaucoma is a “silent thief of sight” that it’s important that families make younger generations aware of whether the disease is in their family so they can monitor their vision.
After her surgery, Hepburn said she’s doing well and isn’t currently on any drops, but she continues to be monitored by doctors, and the level her pressure is at determines how often she goes for checkups.
The nurse encourages people to get their annual eye exams and make them a routine part of their health checks.
“We don’t check our eyes. We just take them for granted,” said Hepburn. “We advise that people 40-plus should get annual eye exams, but if you have a relative with glaucoma, you can’t wait until you’re 40, you need to start having your exams as soon as you know your family has it.”
The nurse said there’s no such thing as glaucoma free. And she said sometimes when you have the surgery you may still need drops.
“Glaucoma can be a frightening disease. There is no cure for it, but the sooner you get treatment the longer you will have your vision,” said Hepburn.
She said they are about to start a support group for people with glaucoma and their relatives to help them cope with information related to how to take their drops, keep their appointments and what to expect.
Glaucoma Awareness Week is also being recognized through Saturday, March 23 under the international theme “Beat Invisible Glaucoma” by the Ophthalmology Division of The Princess Margaret Hospital and The Public Hospitals Authority with the goal to promote community awareness of the eye condition. During the week, free Glaucoma Screening will be provided 9 a.m. – 1 p.m. for staff of the Ministry of Health today, and uniformed officers on Wednesday and Thursday at the PMH Eye Care Center on Soldier Road.
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