Common Eye Diseases
Age-Related Macular Degeneration: What is it?
This is an eye disease of the central retina, the macula, that is associated with aging that gradually destroys sharp, central vision. When the macula becomes damaged, many daily activities such as driving and reading become increasingly difficult.
How many people suffer from AMD?
Age-related macular degeneration (AMD) is a major cause of visual impairment in the United States. Approximately 1.8 million Americans age 40 and older have advanced AMD, and another 7.3 million people with intermediate AMD are at substantial risk for vision loss. The government estimates that by 2030 there could be 6.3 million people affected due to the aging of the Baby Boomers.
What are wet and dry macular degeneration?
There are two forms of (AMD): dry AMD and wet AMD. The dry form, in which the cells of the macula slowly begin to break down, is diagnosed in 85 percent of cases. Both eyes are usually affected by dry AMD, although one eye can lose vision while the other eye appears unaffected. Drusen, yellow deposits under the retina, are common early signs of dry AMD. The risk of developing advanced dry AMD or wet AMD increases as the number or size of the drusen increases. The wet form, accounts for only 15 % of cases but results in 90% of the blindness, and is considered advanced AMD. As the dry form worsens, some people begin to have abnormal blood vessels growing behind the macula. These new blood vessels may then bleed and leak fluid, causing the macula to bulge or lift up, thus distorting or destroying central vision. Under these circumstances, vision loss may be rapid and severe.
How is AMD diagnosed?
We will perform a dilated eye exam, visual acuity test, and view the back of the eye to help diagnose age-related macular degeneration (AMD).
Are there effective treatments for AMD?
At present, there is no known way to prevent macular degeneration. For now, the most important thing to do is to have regular eye exams, which may allow early detection and diagnosis. If dry age-related macular degeneration (AMD) reaches the advanced stages, there is no current treatment to prevent vision loss. However, a specific high-dose formula of antioxidants may delay or prevent intermediate AMD from progressing to the advanced stage. Laser surgery, photodynamic therapy, and treatment with Macugen can destroy or control the growth of the abnormal blood vessels in the macula and is helpful for some people who have wet AMD; however, vision that is already lost will not be recovered. There are also multiple new promising treatment options in development.
Glaucoma: What is it?
Though there are various forms of glaucoma they all result in a loss of vision due to damage of part of the retina called the retinal nerve fiber layer and ultimately the optic nerve. Glaucoma may be associated with high intraocular pressure though this is not always true, in contrast to previous thought. Many forms of glaucoma can occur with the eye pressure never exceeding what is considered “normal.” We take glaucoma very seriously because the vision loss is slow, progressive, and most importantly irreversible.
How is Glaucoma Diagnosed?
Many things are taken into consideration when making the diagnosis of glaucoma. Family history, age, race, prescription, and overall health can all affect one’s risk of developing glaucoma. During the eye examination observation of the optic nerve and the nerve fiber layer, the drainage system, the intraocular pressure, corneal thickness, and visual fields are all assessed.
Optic Nerve & Nerve Fiber Layer
Think of the optic nerve as the conduit for nerve impulses between the retina and the brain. It is composed of hundreds of thousands of nerve axons. These nerve axons originate within the retina and are called the retinal nerve fiber layer when they are within the eye. Our doctors will examine both the optic nerve and the retinal nerve fiber layer. We look at many characteristics of the optic nerve, the most important being what is termed as the cup to disc ratio. This is a number between a 0 and a 1 with the higher number being of greater risk. As glaucoma progresses the number gets larger as more and more of the nerve fibers that travel through the optic nerve are damaged. There are also many technological advances in the field of glaucoma that are allowing us to assess changes at a cellular level and detect changes many years earlier than in the past. The most advanced technology called ocular coherence tomography (OCT) is utilized at BFE to assess changes in the optic nerve and nerve fiber layer.
The eye is a dynamic organ in that it is filled with a fluid called aqueous humor that is continually being produced and drained from within the eye. The intraocular pressure (discussed below) is a function of the balance of fluid production and drainage. During your exam, one of our doctors will examine the drain if the eye using a special diagnostic lens.
Intraocular Pressure & Corneal Thickness
Tonometry, or more commonly ‘eye pressure”, is also assessed. We know that IOP is only one of the risk factors for the development of glaucoma and “normal” pressures are very specific to each person’s situation. The intraocular pressure varies throughout the day and in affected by both the drainage system (mentioned above) and the central corneal thickness. The corneal thickness will also be evaluated during your exam with a small ultrasonic device.
In later phases of the disease, various specialized peripheral field tests are also employed. These tests evaluate the degree of functional vision loss that is occurring with the progression of the disease.
What Do We Notice?
Unfortunately, for most forms of glaucoma, there are no symptoms. Because it is a slow and progressive disease most people are never aware that they have glaucoma until significant damage has already occurred. Because of this, we recommend annual exams to monitor the optic nerve for change.
How Often Should I be Seen?
Due to the slow and lack of symptoms patients who are at greater risk will be seen at least annually. Patients who are diagnosed with glaucoma may be seen as often as 6-week intervals depending on the severity of the disease.
How do We Treat This?
The primary method of treatment at this time is eye drops. There are various forms of eye drops that can be used to reduce the pressure in the eye. Currently, there is no medical treatment to protect the optic nerve or reverse the damage that has already been done. As the disease progresses surgery may be necessary. There are various forms of surgery that may be recommended depending on the type or severity of glaucoma. The non-invasive procedures include laser therapy called either Selective Laser Trabeculoplasty (SLT) or Argon Laser Trabeculoplasty (ALT). Both of these facilitate an increase in the rate of fluid draining from within the eye without ever actually opening the eye. Invasive procedures include a trabeculectomy. Ask one of our doctors about more details on these and other surgical options.
Cataracts: What is it?
Cataracts are a clouding of the eye’s natural crystalline lens that typically causes the vision to become blurry. This natural lens is located behind the iris and pupil. As we get older our lens becomes slightly more yellow every year and slowly loses its clarity. Cataracts are classified as one of three common types:
–Nuclear cataract is most commonly seen. This cataract forms in the nucleus, the center of the lens, and is due to natural aging changes.
–Cortical cataract, which forms in the lens cortex, gradually extends from the outside of the lens to the center in a triangular or “pie-shaped” pattern.
–Sub-capsular cataract begins at the back of the lens near the posterior lens capsule.
What causes it?
No one knows for sure why the eye’s lens changes as we age. Researchers are gradually identifying factors that may cause cataracts. Many studies suggest that exposure to UV light is associated with cataract development, so we recommend wearing sunglasses to lessen your exposure. Other studies suggest people with diabetes are at risk of developing a cataract. Other risk factors include cigarette smoke, air pollution, poor nutrition, and heavy alcohol consumption.
Cataract Symptoms & Signs
A cataract starts out small, and at first, has little effect on your vision. You may notice that your vision is blurred a little, like looking through a cloudy piece of glass. A cataract may make light from the sun or a lamp seem too bright or glaring. Or you may notice when you’re driving at night that the oncoming headlights cause more glare than before. Colors may not appear as bright as they once did. The type of cataract you have will affect exactly which symptoms you experience and how soon they will occur. When a nuclear cataract first develops, it can bring about a temporary improvement in your near vision, called “second sight.” Unfortunately, the improved vision is short-lived and will disappear as the cataract worsens. Meanwhile, a sub-capsular cataract may not produce any symptoms until it’s well-developed. When symptoms begin to appear, you may be able to improve your vision for a while using new glasses, strong bifocals, magnification, appropriate lighting, or other visual aids.
How do we treat it?
Many people consider poor vision an inevitable fact of aging, but cataract surgery is a simple, relatively painless procedure to regain vision. Modern cataract surgery is very successful in restoring vision. In fact, it is the most frequently performed surgery in the United States, with over 1.5 million cataract surgeries performed each year. Nine out of 10 people who have cataract surgery regain very good vision, somewhere between 20/20 and 20/40.
We recommend cataract surgery once your cataracts have progressed enough to impair your vision and affect your daily life. During surgery, the surgeon will remove your clouded lens, and replace it with a clear, synthetic intraocular lens (IOL). New IOL’s are being developed all the time to make the surgery less complicated for surgeons and the lenses more helpful to patients. Currently, there are many options for which type of lens can be implanted including the new multi-focal lenses that help reduce the dependency on reading glasses after surgery. This surgery is typically an outpatient procedure and you can go home the same day. You may be required to use eye drops for the first few weeks after surgery and you will most likely need a new pair of glasses a few weeks after the eye has completely healed.
Some eye care practitioners believe that a diet high in certain antioxidants, such as beta-carotene, selenium, and vitamins C and E, may forestall cataract development. Other ways you can help reduce your risk is to wear quality sunglasses that block all forms of UV, stop smoking, and maintain good general health. Ask your eye care provider at your annual health and vision exam about other options.
Diabetes and the Eye
Diabetes mellitus is one of the leading causes of irreversible blindness worldwide, and, in the United States, it is the most common cause of blindness in people younger than 65 years. In addition to being a leading cause of blindness, diabetic eye disease encompasses a wide range of problems that can affect the eyes such as a reversible, temporary blurring of the vision to severe, permanent loss of vision. Diabetes also increases the risk of developing cataracts and glaucoma. Some people may not even realize they have had diabetes mellitus for several years until they begin to experience problems with their eyes or vision. Severe diabetic eye disease most commonly develops in individuals who have had diabetes mellitus for many years, but they have had little or poor control of their blood sugars over that period of time.
Diabetic Eye Disease Causes
Over many years, high blood sugar may damage the blood vessels in the body. This damage leads to poor circulation of the nutrient-rich blood to various parts of the body and subsequent damage to those tissues. The primary part of the eye affected by diabetes mellitus is the retina. In a similar manner, if the retina is swollen, wrinkled, or otherwise structurally damaged, the vision in that eye will be blurry. Depending on the type and extent of damage in the retina, the change in vision will range from minimal to severe and be temporary or permanent. In people with diabetes mellitus, changes in the walls of the small blood vessels in the retina are caused by blood sugar abnormalities. These small blood vessels may begin to “balloon,” forming what are called microaneurysms, as well as leak fluid (called edema) and blood (called dot and blot hemorrhages) into the retina. This process is called background diabetic retinopathy or non-proliferative diabetic retinopathy. If fluid accumulates in the central part of the retina (called the macula) and causes swelling there, the process is called diabetic macular edema. As a response to decreased oxygen delivery to the retina, new blood vessels may begin to grow, a process called proliferative diabetic retinopathy. Although new blood vessels may sound like a good thing, considering that the old blood vessels are damaged, the new blood vessels are actually more harmful than beneficial. The new blood vessels are extremely leaky and fragile, leading to bleeding inside the eye (called a vitreous hemorrhage) and usually resulting in severe vision loss. If not treated appropriately, this vision loss may be permanent. If the new blood vessels are extensive, they may cause scarring inside the eye, resulting in tractional retinal detachments, which is another cause of permanent vision loss.
If you have fairly large, rapid shifts in your blood sugar levels, you may notice that your vision becomes blurry. This may occur prior to the diagnosis of diabetes mellitus, or it may develop after the initiation of treatment or a change in treatment of diabetes mellitus. The sugar in the blood can diffuse into (or out of) the lens of the eye and cause it to swell (or shrink) resulting in blurring of the vision. This difficulty with vision or focusing will disappear once blood sugar levels have been stable for a few days.
If you watch your diet, perform your exercise routine, monitor your blood sugars, and take your diabetic medications, the chances of developing serious problems from diabetes decrease dramatically. This is especially important in light of the new, more accurate definition of diabetes mellitus that estimates 41 million people in the United States have “pre-diabetes,” a condition that significantly increases the risk for developing this disease. The most important method of preventing eye disease related to diabetes is to maintain strict control of your blood sugar. High blood pressure and high lipid or cholesterol levels must also be treated to decrease damage to the blood vessels within the eye.
When to Seek Medical Care
Even if you are not experiencing any symptoms due to your diabetes mellitus, you should have annual eye examinations. If you note any significant changes in your vision other than a mild temporary blurring, you should contact us immediately.
Diabetic Eye Disease Treatment
Medical treatment of diabetic eye disease is generally directed at the underlying problem – diabetes itself. The better control you have of your diabetes, the fewer problems you will have in the long run.
– Currently, effective medications do not exist to directly treat diabetic retinopathy, and surgery (ie, laser) is the treatment of choice. Surgery
– Surgical treatment of diabetic eye disease most commonly involves the treatment of the retina with an argon laser.
For background diabetic retinopathy, focal/macular photocoagulation, or grid macular photocoagulation is performed. During this laser treatment, a highly focused beam of laser light is used to treat the leaking blood vessels or to treat the area of retinal swelling.
For proliferative diabetic retinopathy, panretinal photocoagulation (PRP) is performed. During this treatment, the entire retina, except for the macula (the center of the retina), is treated with laser spots to decrease the oxygen demand of the retina and remove the need for these new blood vessels to grow.