Glaucoma

Glaucoma is a general term used to describe a group of eye diseases that gradually steal sight. There may be no warnings or symptoms. Vision loss is caused by damage to the optic nerve. The optic nerve can be described as similar to a cable that extends from the back of each of your eyes to your brain. It has more than a million fibers that transmit messages to the brain about what your eyes see. Unfortunately, damage caused by glaucoma is permanent and vision lost to glaucoma cannot be restored.

Understanding Glaucoma

Patients may present with one or several of these symptoms:

It was once thought that high intraocular pressure (IOP) was the main cause of this optic nerve damage. We now know that glaucoma is a multi-factored disease. Current theories as to the cause of glaucoma include increased pressure within the eye, decreased blood flow to the eye and genetics.

TYPES OF GLAUCOMA:

Open Angle Glaucoma

Open angle glaucoma is the most common form of glaucoma, accounting for nearly 80% of all glaucoma cases.
This type of glaucoma often runs in families, but does not always affect every member of the family. Sometimes only one person in a family will have glaucoma and it can skip one or more generations. It almost always affects both eyes.
Generally, individuals with open angle glaucoma experience no symptoms. By the time you are aware of vision loss, the degree of optic nerve damage is quite advanced and irreversible.
Some definitive signs of open angle glaucoma include increased intraocular pressure (IOP), enlargement of the optic nerve cup, decreased peripheral vision, retinal nerve fiber layer thinning, and optic disc hemorrhages.

Acute Angle-Closure Glaucoma

This type of glaucoma accounts for 10% of glaucoma in the United States and is most common in Eskimos and Asians.
Most people who are predisposed to developing this type of glaucoma have no signs or symptoms before its onset.
Those who have been diagnosed with narrow angle glaucoma should avoid taking over-the-counter cold and allergy remedies. These can cause the pupils to dilate and, in rare instances, can cause people with narrow angles to have an acute angle-closure attack. This could lead to an increase in eye pressure.
Narrow angle glaucoma attack symptoms include severe eye pain and redness, decreased or tunnel vision, colored halos, extreme headache, light sensitivity, nausea, vomiting and abdominal discomfort. A person may have one or more of these symptoms, but not everyone has all of them.

Low Tension or Normal Tension Glaucoma

This is when optic nerve damage occurs in people with normal or low eye pressure.
Reducing the pressure further with medicines can sometimes slow the progression of damage to a person’s vision.

Congenital Glaucoma (Birth Defect Glaucoma)

Congenital glaucoma refers to glaucoma which can be either present at birth or appear anytime during the first three or four years of life. It occurs only in about 1 out of 10,000 infants.
Elevated intraocular pressure is caused by an abnormal drainage canal (trabecular meshwork) in the eye. Although congenital glaucoma may be inherited, in most cases it is not. Most babies with congenital glaucoma are born to healthy parents.
Although both eyes are most commonly affected, glaucoma is often more severe in one eye than in the other.
Children with glaucoma make up 2% to 15% of the population in facilities for the blind.

Secondary Glaucoma (Caused by other Diseases or Medications)

Secondary glaucoma describes a group of glaucomas caused by some other identifiable eye or systemic disease, eye surgery, eye trauma, prolonged use of certain medications, or ocular inflammation.
There are many causes of secondary glaucoma. These can be either the open angle or narrow angle variety.
This type of glaucoma is unlike chronic open angle glaucoma in that when the problem causing raised intraocular pressure is corrected or cured (if possible), the pressure may return to normal and further medication may be unnecessary. Unfortunately, existing damage to the visual field will remain.

Pigmentary Glaucoma

Usually a secondary glaucoma, this type occurs when pigment from the iris flakes off and blocks the meshwork, slowing fluid drainage, and increasing pressure within the eye that leads to optic nerve damage and resulting loss of vision.

How Does Glaucoma Damage Sight?

Intraocular Pressure – a Primary Cause of Glaucoma

Your eyes continuously produce a clear, thin fluid called aqueous humor. It is produced by the ciliary body, located behind your iris, the colored part of your eyes. The aqueous humor fills the space between the cornea and the iris, also referred to as the anterior chamber of the eye. This fluid nourishes the cornea, the iris and the lens, and gives the front of the eye its form and shape.

The intraocular pressure of the eye is maintained at normal levels when the aqueous humor produced by the eye is allowed to flow out. When the aqueous humor is overproduced or not allowed to flow out effectively through the eye’s drainage canal (trabecular meshwork), the intraocular pressure increases, causing damage to the optic nerve and leading to vision loss.

Elevated Intraocular Pressure Causes Optic Nerve Damage

The optic nerve starts in the eye. All the visual nerve fibers in the eye come together at the optic nerve head. They then exit the eye and proceed to the brain. Near the center of the optic disc is the point called the cup. The blood vessels going from the body to the eye pass through the center of the optic nerve and along the nasal side of the cup into the eye. The nerve fibers surrounding the cup are pink.

In glaucoma, elevated pressure within the eye compresses the optic nerve, constricts blood vessels that nourish sensitive visual structures in the back of the eye and thins the retinal nerve fiber layers. Reduced blood supply to these sensitive structures causes nerve cells to die and loss of vision results.

As the pink nerve fiber tissue dies off, it is replaced with whitish fibrous tissue and the central cup becomes larger. If left untreated, this glaucoma damage continues and the cup becomes even larger. This enlargement of the optic nerve cup is called “cupping.” Cupping is an absence of nerve tissue, and is usually accompanied by loss of vision.

As glaucoma affects the optic nerve, the vision loss will involve your peripheral vision first (what you see around you while looking straight ahead), not your central vision. Loss of vision to glaucoma is usually a gradual progressive loss that most patients do not notice initially. Once vision is lost, it cannot be restored. Glaucoma will lead to blindness if left undetected and untreated.

How is Glaucoma Diagnosed?

The early detection of glaucoma is key to controlling its progression and preventing further damage. Comprehensive eye examinations, including tests aimed at measuring the pressure in your eyes (tonometry), evaluating the appearance of your optic nerve (ophthalmoscopy), observing the drainage angles (gonioscopy), and checking for the presence of any loss in peripheral vision (visual field testing), are critical to properly diagnosing glaucoma.

Additional diagnostic tests that give your doctor more in-depth details not visible with the human eye are also performed to diagnose and monitor the progression of glaucoma.

There is no cure for glaucoma, but treatment can usually prevent blindness. If left untreated, glaucoma can lead to complete and irreversible blindness.

Until a cure is found, glaucoma can be controlled and managed through lifelong treatment. Medication and surgery can effectively stop or slow the progression of the disease. Much is happening in research that makes us hopeful that a cure may be in the future.

The opposite problem – over-production of oils – may result in blepharitis, which may block the flow of oil to the eyes and cause tears to evaporate too quickly.

Who Is At Risk For Glaucoma?

Glaucoma is a nondiscriminatory disease that attacks people of all races and backgrounds. However, if you fall into any of the categories listed below, you are at higher risk for developing glaucoma.

You have consistently elevated intraocular pressures
You are an adult over the age of 60
You are of African-American descent
You have a family history of glaucoma
You have low systemic blood pressure (hypotension)
You have Diabetes
You are very nearsighted (myopic)
You have experienced trauma to the eye(s)
You suffer from unexplained headaches and eye-pain
You suffer from ocular migraines

Glaucoma Treatments

The purpose of glaucoma treatment is to lower and control intraocular pressure (IOP). It may take a combination of methods to achieve this. The first step in most glaucoma treatment plans includes oral medication and/or eye drops. If this is not sufficient enough to control IOP, surgery may be necessary.

The goal of treatment is to stop further vision loss from occurring, but cannot bring back any vision lost to glaucoma. This is why early diagnosis of glaucoma is key to preventing vision loss and blindness.

Selective Laser Trabeculoplasty (SLT)

SLT is typically recommended after having been unsuccessfully treated using medications. If you want to decrease or eliminate the use of eye drops, this treatment may be beneficial as well.

The goal of SLT is to treat open angle glaucoma patients by helping drain fluid from the eye. This treatment prevents damage to the optic nerve and the resulting vision loss. During this procedure, your surgeon will focus a laser through a special lens. This laser will start a chemical and biological change in the tissue of the eye that allows for better drainage, therefore lowering IOP. It can take a few months to see results from this procedure.

Laser Iridotomy

Laser iridotomy uses a focused beam of light to create a hole on the outer edge of the iris. This hole allows fluid to properly drain from the eye, alleviating high IOP. This procedure is generally performed on people with narrow angle glaucoma, which is a medical emergency.

Endoscopic Cyclophotocoagulation (ECP)

ECP has been shown to decrease dependence on medications for patients with glaucoma. This procedure is started by creating an incision in the periphery of the cornea to gain access to the ciliary body. The ciliary body is responsible for creating the fluid that nourishes the inside of your eye. When this fluid is being overproduced, or if it is not able to drain properly, glaucoma can occur.

The next step in this procedure includes the use of an endoscopic laser to ablate the ciliary processes, which will reduce IOP.

Have you been diagnosed with glaucoma? Consider Tyson Eye for your glaucoma treatment! Our glaucoma experts are experienced and skilled at finding the perfect treatment to preserve your vision. Contact our Naples office to schedule an appointment with us today!