Glaucoma : The Silent Thief of Vision

According to the World Health Organization (WHO), glaucoma is the second leading cause of blindness in the world, after cataract. Glaucoma is a group of related eye diseases that cause damage to the optic nerve. Vision loss due to glaucoma occurs when the eye pressure is too high and this damages the optic nerve. The eye pressure is produced by the presence of fluid, called aqueous humor, in the front compartment of the eye. The aqueous humor is made by the ciliary body which acts like a faucet. It then passes through the pupil and gets out of the eye into the bloodstream through the eye’s drainage system. If this system is not working properly, the fluid is blocked from going out which will result in a fluid build-up. The eye pressure can be measured by eye doctors using the Tonometry.

The WHO also reported that glaucoma is responsible for approximately 5.2 million cases of blindness (15 percent of the total burden of world blindness).

Although unique to each person, the range for normal eye pressure is 12-22 mm Hg (“mm Hg” refers to millimeters of mercury, a scale used to record eye pressure). Most glaucoma cases are diagnosed with pressure exceeding 20mm Hg. The WHO identified three main forms of the disease namely congenital glaucoma, primary open-angle and primary angle-closure glaucoma.

Congenital glaucoma refers to the presence of glaucoma in a child which can be due to a hereditary defect or abnormal development during pregnancy. It is usually diagnosed within the first year of life. Symptoms include enlarged eyes, excessive tearing, cloudiness of the cornea and sensitivity to light (photosensitivity). This can be treated with medication and surgery.Primary open angle glaucoma is the most common form of glaucoma. The drainage system is open and visible; however, it is unable to drain the fluid out just like a pipe with a clogging problem. This is symptomless and is described as a “silent thief of vision.” If left undiagnosed and untreated, it can cause a painless gradual loss of vision. However, it usually responds well to medication, especially if diagnosed and treated early.

Angle closure glaucoma is much more rare form of the disease. It is more commonly seen in people of Asian heritage. Unlike open angle glaucoma, this causes a quick rise in eye pressure due to a total closure of the drainage system. The drain is covered by the abnormal adherence of the iris. Symptoms of an acute attack of angle closure glaucoma include headache, eye pain, nausea, seeing halos around lights and ultimately severe blurring of vision which can happen fast. Treatment for this form of glaucoma should be prompt and can either be through laser or surgery. It is advised that the other eye undergoes laser treatment also for preventive measures.

In spite of the advances in medicine and surgical techniques, there is no cure yet for glaucoma. However, the potentially blinding eye condition is preventable and manageable. Glaucoma is diagnosed if there is optic nerve damage and visual field defect. High technology machines are used to document these evidences of damage.

The Optical Coherence Tomography (OCT) is a computerized optic nerve imaging technique which is used for early detection of optic nerve thinning even before detectable visual field loss sets in. It directly measures the thickness of the nerve fiber layer which needs to be monitored for glaucoma progression.

Perimetry is a visual field test that maps out any decrease in light sensitivity. The test detects early peripheral or side vision loss which is a characteristic of glaucoma. It is repeated once or twice a year to monitor glaucoma progression.

It is vital to have your eyes examined. The Medical City Clark encourages the public to have their eyes checked. Perimetry and Optical Coherence Tomography (OCT) are both available in this hospital.

Dr. Rochelle Sumagang, the author of this article is an ophthalmologist at The Medical City Clark. In 1993 she took up Bachelor of Science in Medical Technology at The University of Santo Thomas and finished her degree in medicine in the same university in 1997.
Her post graduate training include Glaucoma Fellowship at the Eye Referral Center in Manila and ECCE, Manual SICS and Phacoemulsification at the Arvind Eye Hospital in India (?).

You can visit Dr. Rochelle Sumagang at Eye Center- TMC Clark- Ambulatory Surgical Center every Monday 11 am to 1 pm. To set an appointment you can reach us at (045) 300-8888.

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