The Silent Thief of Sight


Glaucoma is the second leading cause of blindness in the United States, but of the millions of people affected by it, many are unaware the condition is present.

“Nearly 4 million people are estimated to have glaucoma, but half don’t know it,” confirms Lee Shettle, DO, a board-certified ophthalmologist at Shettle Eye Research who conducts clinical research in partnership with ophthalmic pharmaceutical companies.

Dr. Shettle’s research aims at assisting ophthalmic pharmaceutical companies in developing new medical eye drops to treat various eye conditions such as dry eye disease and ocular inflammation. He is currently enrolling patients in a clinical study testing treatments for glaucoma.

Glaucoma is a condition in which increased pressure in the eye causes damage to the optic nerve, which can lead to blindness if untreated.

“The increased eye pressure is caused by either an overproduction of eye fluid called aqueous humor or a decrease in drainage of aqueous humor through the trabecular meshwork,” explains Dr. Shettle, who has been practicing general ophthalmology in Largo since 1994. “In a healthy eye, aqueous humor exits the eye at the same rate as the eye’s ciliary body produces it, so there is always a balance in pressure within the eye.

“With glaucoma, aqueous either passes too slowly through the trabecular meshwork or the ciliary body produces an increased amount of aqueous humor. You can think of it as a faucet being turned on too high or the drain in the sink being clogged, resulting in a buildup of fluid.

“Glaucoma has no obvious visual symptoms in its early stages. As it progresses over many years, damage occurs to the optic nerve, resulting in loss of peripheral vision. Without treatment, this loss of vision can progress to blindness, robbing people of their vision slowly and quietly. It’s a silent thief of sight.”

Types of Glaucoma

There are different types of glaucoma, including open-angle glaucoma, also called wide-angle glaucoma. This is the most common type and represents about 90 percent of cases in the US. Less common types include closed-angle glaucoma, normal-
tension glaucoma, congenital glaucoma and secondary glaucoma.

Closed-angle glaucoma, also called narrow-angle glaucoma, occurs when there’s a blockage in the eye, causing a sudden rise in pressure. Closed-angle glaucoma is an emergency and requires immediate medical attention to prevent permanent damage to the optic nerve and vision loss.
The cause of normal-tension glaucoma is not completely understood, but most doctors believe it’s related to reduced blood flow to the optic nerve. Congenital glaucoma is hereditary and often diagnosed in very young children. It results when the eye doesn’t form properly during development.

Secondary glaucoma is the result of another condition, such as diabetes.

Some people are at greater risk for developing glaucoma.

“Glaucoma is more common in certain populations,” Dr. Shettle expresses. “The people at highest risk for glaucoma include African American and Hispanic patients over the age of 40; everyone over the age of 60; and, especially, anyone with a family history of glaucoma, particularly if a parent or sibling has the disease.”

People are also at greater risk for glaucoma if they have certain medical conditions such as diabetes, heart disease and high blood pressure. Other risk factors include having had a previous eye injury, being farsighted or nearsighted, and taking steroid medications for a long time.

Halting Progression

Treatment for glaucoma aims to slow the disease progression. It may include medicated eyedrops, a laser procedure or surgery.

“For patients with mild glaucoma, the use of medicated eyedrops or a laser treatment to lower intraocular pressure may be all that’s needed to keep the disease under control,” Dr. Shettle states.

Medicated eyedrops alter the production of fluid and lower pressure in the eye. They work by either decreasing the production of aqueous humor or increasing the amount of aqueous humor exiting through the trabecular meshwork.

Nearly 4 million people are estimated to have glaucoma, but half don’t know it! -Dr. Shettle

Trabeculoplasty and iridotomy are laser procedures used to treat glaucoma. During trabeculoplasty, the laser is applied to the drainage tissue, where it starts a physical and chemical reaction that improves drainage function.

Iridotomy treats narrow-angle glaucoma. During this procedure, the laser is used to create tiny holes in the iris to improve the flow of fluid within the eye.

In more advanced stages of glaucoma, patients may require a procedure called surgical trabeculectomy, in which surgeons create a small hole in the eye wall. The wall is covered by a flap of tissue that serves as a trap door through which excess fluid drains to an area under the eye’s surface.

“As it is with most conditions, early detection is critical when treating glaucoma,’’ Dr. Shettle emphasizes. “And treatment is crucial to prevent the progression of this common eye disease.”

Because glaucoma in its early stages has no symptoms, people with the disease often don’t seek medical attention until some vision loss has begun.

“Screening for glaucoma should be part of all routine eye exams, which every patient should have at least every year or two, based on their risk,” Dr. Shettle observes. “Tests for glaucoma include measuring the eye pressure as well as analyzing the optic nerve for changes.”

© FHCN article by Patti DiPanfilo. Ad graphic courtesy of Shettle Eye Research, Inc. mkb
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    • Shettle Eye Research, Inc.

      Dr. Shettle sees all of his patients himself to establish a more personal relationship. He is dedicated and committed to taking the time to help each and every patient understand their unique visual, medical or surgical co... Read More

    • Lee Shettle, DO

      Lee Shettle, DO, is board certified by the American Osteopathic Board of Ophthalmology and Otorhinolaryngology. He received his Bachelor’s degree in Biology from Northeast Missouri State University in Kirksville, then earned his Doctor of Osteo... Read More