Most people have heard of the eye disease called Glaucoma, however the majority are unaware of what makes Glaucoma such a threatening eye problem. Unlike many other eye diseases, conditions or problems Glaucoma most often begins without any symptoms or obvious loss of vision. In this way it is quite insidious and, if not diagnosed early in its course, will lead to progressive unnoticed vision loss. This is what makes Glaucoma an eye disease to be diagnosed and reckoned with early in its course.
Glaucoma is actually a broad term that is used to characterize a broad range of eye problems that damage the optic nerve and potentially cause loss of vision. Most people share the common belief that Glaucoma is simply due to a high pressure within the eye. The pressure inside the eye is called Intraocular Pressure (IOP) and generally falls within some normal range. While a high Intraocular pressure certainly can be one cause of Glaucoma, and in fact is the most common cause of Glaucoma, a high IOP is not the only cause of Glaucoma by any means. There are numerous causes of Glaucoma and the more common ones are discussed in the following text. No matter what the cause, all Glaucomas share a common factor-if not diagnosed early, treated properly and controlled, they will result in permanent vision loss and potentially blindness.
Glaucoma is a leading cause of blindness for patients between the ages of 18-65 years of age-in fact it is only second to cataracts. It is believed that only half of the people who have Glaucoma actually know that they have it. Over 2.25 million Americans over the age of 40 years old have Primary Open Angle Glaucoma, which will be discussed here. National studies estimate that between 3-6 million people in the United States have higher than normal Intraocular Pressure, without obvious clinical signs of damage to the optic nerve. Thus it is likely that there are another million people who may have Glaucoma, but have not yet been diagnosed because they do not have access to eye care or even Glaucoma screenings. Just in the United States, there are approximately 100,000 patients who are believed to be legally blind from glaucoma.
As mentioned above, the most disturbing characteristic of Glaucoma is that the course of the eye disease, beginning with its slow onset and lack of visual symptoms is likely to go unnoticed by patients unless they are consistent about having routine eye examinations with Glaucoma testing. It is entirely possible to have a higher than normal Intraocular Pressure (IOP) and vision loss and simply not know it. As an absolute minimum clinical care standard, patients over 50 years of age who have no previous family history of Glaucoma or other general health conditions such as diabetes or high blood pressure should be evaluated for Glaucoma every two years. If there is any family history of Glaucoma at all, or any other general health problems, patients should be evaluated for Glaucoma every year beginning at 40. Further, there is considerable risk for siblings of those who have Glaucoma. The Nottingham Glaucoma Study demonstrated that siblings of Glaucoma patients are at particularly high risk for developing Glaucoma by the age of 70 and should be repeatedly screened on an annual basis.
Causes & Types of Glaucoma
In the normal eye, there is a constant production and drainage of fluid called Aqueous Humor. This production and drainage is balanced so as to maintain a “normal’ Intraocular Pressure (IOP).
Aqueous Humor is produced by the Ciliary Body, a structure positioned just behind the Iris, or colored part that is visible. Aqueous Humor is normally drained through a structure called the Trabecular Meshwork, which is a tissue meshwork located at the base of the Iris. Any time there is a disturbance in either too much Aqueous Humor being produced or too little fluid being drained, there is a rise in pressure. It is best to have an equilibrium of Aqueous Humor fluid so that a “normal” pressure in the eye is created.
Primary Open Angle Glaucoma
By far, the most frequently diagnosed type of Glaucoma in the United States is Primary Open Angle Glaucoma (POAG). Patients with Primary Open Angle Glaucoma, typically demonstrate an increase in Intraocular Pressure (IOP) upon routine measurement. The increased Intraocular Pressure (IOP) results from either too much Aqueous Humor being produced or too little being drained as mentioned above. This fluid buildup within the closed space of the inside of the eye elevates the pressure. It is this raised pressure (IOP) that can cause permanent changes and even damage to the optic nerve resulting in vision loss. The optic nerve is the connection between the retina and the brain and is responsible for communicating visual images. Once the optic nerve is damaged, it is not able to carry this visual images, resulting in vision loss. This is why it is so important to monitor, detect and control Intraocular Pressure (IOP). If left untreated, an elevated Intraocular Pressure (IOP) may, over time, cause slow progressive, permanent damage to the optic nerve that can result in blindness.
Angle Closure Glaucoma
Angle Closure Glaucoma is found much less frequently than Open Angle Glaucoma, but is nonetheless quite important as it has the ability to produce considerable vision loss in a short period of time. Angle Closure Glaucoma is characterized by closure or blockage of the drainage structure of the eye-the Trabecular Meshwork. The Trabecular Meshwork is actually a tiny tissue filter, that if blocked by a change in size or shape of the tissue, will cause the Intraocular Pressure to elevate. In instances where the meshwork becomes blocked abruptly, it will cause a sudden rise in the Intraocular Pressure (IOP). This sudden rise in pressure can cause pain, redness, blurred vision and if left untreated permanent loss of vision.
While there can be a number of causes of Angle Closure Glaucoma, it is most often caused by anatomical changes within the internal structures of the eye. Angel Closure Glaucoma is considerably more common in farsighted eyes, which tend to be smaller and in patients between the ages of 45-60 years of age where the Crystalline Lens is beginning to swell. During your general eye exam if the eye doctor observes or measures a narrowed angle, he or she will perform an additional examination procedure called Gonioscopy to fully visualize the meshwork and the angle in order to carefully assess your predisposition to Angle Closure Glaucoma. This test is performed by placing a special contact lens on the eye and then using the slit lamp biomicroscope to fully examine the meshwork and the angle. In the event that you are at risk for Angle Closure Glaucoma or in the event that you have Acute Angle Closure Glaucoma, the most effective form of treatment is to use a Laser to produce a small opening or hole in the Iris so that Aqueous Humor can quickly and efficiently drain from the eye by preventing the Trabecular meshwork from being blocked.
Glaucoma Risk Factors
Glaucoma is a well studied eye disease and fortunately we know many of the factors that can predispose patients to being at risk. Some of these factors by themselves are highly predictive and others are more important when combined with other risk factors
- Increased Intraocular Pressure-Anyone who has been found to have an elevated Intraocular Pressure (IOP) at a Glaucoma screening or as part of a general eye examination is considered to be at risk for developing Glaucoma.
- Age-The incidence of Glaucoma increases as we get older. Typically the incidence of Glaucoma become much more noticeable above the age of 40 years old. This is why routine eye examinations with Glaucoma evaluation are recommended every 2 years above the age of 40 if there is no other family or medical history and more often if there is a preexisting history of Glaucoma in the family or other predisposing heath factors.
- Race - African-Americans to have certain genetic factors that cause a higher likelihood of developing Glaucoma.
- Myopia-In general patients who are nearsighted have anatomical features that may increase the risk of Glaucoma.
- Hypertension-Those patients who are being medically treated for high blood pressure may be at greater risk for Glaucoma due to the lowering of the blood pressure within the optic nerve.
- Diabetes-Anyone being treated for diabetes is considered to be at greater risk for Glaucoma due to the general circulation problems associated with diabetes.
- Family History-Family history of Glaucoma is a very significant risk factor. If any other family members have been diagnosed with Glaucoma, your risk of developing Glaucoma increases considerably. This is particularly true for siblings of Glaucoma patients, who according to the Nottingham Glaucoma Study, as previously mentioned, have a 5-fold increase in risk for developing Glaucoma.
- Some other risk factors include diabetes, hypertension and myopia.
Treatment of Glaucoma
The good news is that glaucoma is a preventable and treatable disease if diagnosed at an early stage. Thanks to advances in medical, Laser treatment and surgical treatment for Glaucoma, there are many treatment options depending on the severity and the actual clinical response you may have to each.
The goal of any treatment is to prevent loss of vision, as vision loss from glaucoma is irreversible. With medical and/or surgical treatment, most people with glaucoma will not lose their sight.
Taking medications regularly, as prescribed, is crucial to preventing vision-threatening damage. While every drug has some potential side effects, it is important to note that many patients experience no side effects at all. Our glaucoma doctors will work with our patients as a team in the battle against glaucoma. Many options can be integrated in your treatment plan includes:
Eye Drops
It is important to take your medications regularly and exactly as prescribed if you are to control your eye pressure. Since eye drops are absorbed into the bloodstream, ask our doctors if the medications you are taking together are safe. Some drugs can be dangerous when mixed with other medications. To minimize absorption into the bloodstream and maximize the amount of drug absorbed in the eye, close your eye for one to two minutes after administering the drops and press your index finger lightly against the inferior nasal corner of your eyelid to close the tear duct which drains into the nose. While almost all eye drops may cause an uncomfortable burning or stinging sensation at first, the discomfort should last for only a few seconds.
Pills
Sometimes, when eye drops don't sufficiently control IOP, pills may be prescribed in addition to drops. These pills, which have more systemic side effects than drops, also serve to turn down the eye's faucet and lessen the production of fluid. These medications are usually taken from two to four times daily. It is important to share this information with our doctors so they can prescribe medications for you which will not cause potentially dangerous interactions.
Surgical Procedures
When medications do not achieve the desired results, or have intolerable side effects, your ophthalmologist may suggest surgery.
- Laser Surgery
Laser surgery has become increasingly popular as an intermediate step between drugs and traditional surgery. The most common type performed for open-angle glaucoma is called trabeculoplasty. This procedure usually cause minimal discomfort and is painless, and can be performed in our office. The laser beam is focused upon the eye's drain. Contrary to what many people think, the laser does not bum a hole through the eye. Instead, the eye's drainage system is changed in very subtle ways so that aqueous fluid is able to pass more easily out of the drain, thus lowering IOP.
Our doctor will check your eye pressure following laser surgery before you will resume your normal activities following surgery. After this procedure, many patients respond well enough to be able to avoid or delay surgery. While it may take a few weeks to see the full pressure-lowering effect of this procedure, during which time you may have to continue taking your medications, many patients are eventually able to discontinue some of their medications. Complications from laser are minimal, which is why this procedure has become increasingly popular and are recommending the use of laser before drops in some patients.
- Selective Laser Trabeculoplasty (SLT) -- for open-angle glaucoma
SLT is a newer laser that is replacing “older” version of trabeculoplasty (ALT) which utilizes very low levels of energy. It is termed "selective" since it leaves portions of the trabecular meshwork intact. For this reason, it is believed that SLT, unlike other types of laser surgery, may be safely repeated.
- Laser Peripheral Iridotomy (LPI) -- for angle-closure glaucoma
This procedure is used to make an opening through the iris, allowing aqueous fluid to flow from behind the iris directly to the anterior chamber of the eye. This allows the fluid to bypass its normal route. LPI is the preferred method for managing a wide variety of angle-closure glaucoma that have some degree of pupillary blockage. This laser is most often used to treat an anatomically narrow angle and prevent angle-closure glaucoma attacks.
- Cycloablation
Two laser procedures for open-angle glaucoma involve reducing the amount of aqueous humor in the eye by destroying part of the ciliary body, which produces the fluid. These treatments are usually reserved for use in eyes that either have elevated IOP after having failed other more traditional treatments, including filtering surgery, or those in which filtering surgery is not possible or advisable due to the shape or other features of the eye. Transscleral cyclophotocoagulation uses a laser to direct energy through the outer sclera of the eye to reach and destroy portions of the ciliary processes, without causing damage to the overlying tissues. With endoscopic cyclophotocoagulation (ECP), the instrument is placed inside the eye through a surgical incision, so that the laser energy is applied directly to the ciliary body tissue
- Traditional Surgery
Trabeculectomy
When medications and laser therapies do not adequately lower eye pressure, our doctor may recommend conventional surgery. The most common of these operations is called a trabeculectomy, which is used in both open-angle and closed-angle glaucomas. In this procedure, the surgeon creates a passage in the sclera (the white part of the eye) for draining excess eye fluid. A flap is created that allows fluid to escape, but which does not deflate the eyeball. A small bubble of fluid called a "bleb" often forms over the opening on the surface of the eye, which is a sign that fluid is draining out into the space between the sclera and conjunctiva. Occasionally, the surgically created drainage hole begins to close and the IOP rises again. This happens because the body tries to heal the new opening, as if it was an injury. Many surgeons perform trabeculectomy with an anti-fibrotic agent that is placed on the eye during surgery and reduces such scarring during the healing period. The most common anti-fibrotic agent is Mitomycin-C
About 60 to 70 percent of patients no longer require glaucoma medications after surgery for a significant length of time. Thirty-five to 40 percent of those who still need medication have better control of their IOP. A trabeculectomy is usually an outpatient procedure. The number of post-operative visits to the doctor varies, and some activities, such as driving, reading, bending and heavy lifting must be limited for two to four weeks after surgery.
- Drainage Implant Surgery
Several different devices have been developed to aid the drainage of aqueous humor out of the anterior chamber and lower IOP. All of these drainage devices share a similar design which consists of a small silicone tube that extends into the anterior chamber of the eye. The tube is connected to one or more plates, which are sutured to the surface of the eye, usually not visible. Fluid is collected on the plate and then absorbed by the tissues in the eye. This type of surgery is thought to lower IOP in patients whose IOP cannot be controlled with traditional surgery or who have previous scarring.
- Nonpenetrating Surgery
Newer nonpenetrating glaucoma surgery, which does not enter the anterior chamber of the eye, shows great promise in minimizing postoperative complications and lowering the risk for infection. However, such surgery often requires a greater surgical acument and generally does not lower IOP as much as trabeculectomy. Furthermore, long term studies are needed to assess these procedures and to determine their role in the clinical management of glaucoma patients.Some Promising Surgical Alternatives
The ExPress mini glaucoma shunt is a stainless steel device that is inserted into the anterior chamber of the eye and placed under a scleral flap. It lowers IOP by diverting aqueous humor from the anterior chamber. The ExPress offers the glaucoma surgeon an alternative to either repeating a trabeculectomy or placing a more extensive silicone tube shunt in those patients whose IOP is higher than the optic nerve can tolerate.
The Trabectome is a new probe-like device that is inserted into the anterior chamber through the cornea. The procedure uses a small probe that opens the eye's drainage system through a tiny incision and delivers thermal energy to the trabecular meshwork, reducing resistance to outflow of aqueous humor and, as a result, lowering IOP.
Canaloplasty, a recent advancement in non-penetrating surgery, is designed to improve the aqueous circulation through the trabecular outflow process, thereby reducing IOP. Unlike traditional trabeculectomy, which creates a small hole in the eye to allow fluid to drain out, canaloplasty has been compared to an ocular version of angioplasty, in which the physician uses an extremely fine catheter to clear the drainage canal.
Glaucoma is a very complex eye disease, and not simply an elevated Intraocular Pressure (IOP). Nonetheless, when detected early it can be successfully treated. D’Ambrosio Eye Care and their staff, under the medical direction of Dr. Francis D”Ambrosio Jr. perform the full scope of advanced technology diagnostic testing and treatment, as well as taking the time necessary to provide each patient the personal education needed to fully understand their condition and get the best possible outcomes for their patients. If you or a family member or friend have not had a recent screening and examination for Glaucoma, please take a moment to request an appointment.
D’Ambrosio Eye Care under the direction of Boston Ophthalmologist Francis D’Ambrosio Jr., M.D. provides diagnosis and treatment of Glaucoma in greater Boston Massachusetts and is conveniently located for Massachusetts Glaucoma patients from Lancaster, Acton, Gardner, Athol, Greenfield, West Springfield, Springfield, Shelburne Falls, Clinton, Harvard, Gardner, Fitchburg, Westminster, Templeton, Worcester, Milford, Marlborough, Boxborough, Westborough, Lowell, Lexington, Leominster, Lunenburg, Shirley, Winchendon. Sterling, Littleton, Boylston, Hudson, Berlin, Bolton, Stowe, Sudbury, Chelmsford, Groton and Concord Massachusetts. To schedule an appointment for a Glaucoma Examination please call us at 1.800.325.3937.
