CATARACTS
A cataract is a clouding of the lens of the eye, resulting in a loss of vision. The lens is the structure just posterior to the iris (the color part of the eye). Most types are related to aging – by age 80 more than half of Americans either have a cataract or have had cataract surgery. In the healthy state, the transparent lens allows the passage of light through to the retina. When a cataract forms, the cloudy lens does not allow as much light through and vision becomes dull or blurry, and colors lose their brightness. Lights at night may have halos around them.
The lens is made mostly of water and protein. As we age, the proteins clump together creating a loss of transparency. The doctor notices the color of the lens becoming a yellow-green. Generally, cataracts can not be seen with the naked eye – external, surface ocular scars are not cataracts, though many people call them that. A slit-lamp microscope is used to determine the presence or absence of the problem.
Risk factors for cataracts include age (primarily), certain diseases like diabetes, smoking, alcohol use, steroid use, and prolonged exposure to the ultraviolet (UV) radiation in sunlight. It has become routine to recommend UV protection in all eyewear for patients, including wearing sunglasses outdoors, in an attempt to reduce the risk of this problem later in life. Many believe a diet rich in antioxidants is also beneficial, as is the case with macular degeneration (see below).
In the early stages, the patient’s vision may be improved with simple prescription changes. However, the problem usually escalates to the point that surgery is required. Cataract surgery is one of the most common surgical procedures performed in this country; 90% of patients that have a cataract removed have better vision afterward. The procedure is done on an out-patient basis and only requires perhaps a half-day at the surgeon’s office. The cataract is removed and an artificial lens, or implant, is inserted to replace it. The implant is necessary to replace the refractive power of the eye lost by removing the lens. Without the implant, a post-op cataract patient would require very thick spectacle lenses. Eyedrops are generally used to promote healing and prevent infection for a few days. Heavy exercise is discouraged for several weeks – but overall, the adjustment in lifestyle is minimal and quite temporary.
The exciting thing about modern cataract surgery is that the surgeons have become quite adept at calculating an implant power that often leaves the patient requiring minimal to no distance correction post-operatively. Readers are still required, unless the patient opts for one of the new types of implant. Generally the patient’s medical insurance – which is usually Medicare for this problem - covers a large part of the fees. Patients may now elect to pay more out-of-pocket for a multifocal implant, which could allow them good vision at all ranges, without any correction, after surgery (see the Refractive Surgery page, Lens Implant procedures).
Some patients develop what is commonly referred to as an “after-cataract” several months to years after the surgery; this is a clouding of the tissue surrounding the implant. It is easily fixed by a quick and painless laser procedure at the surgeon’s office.
GLAUCOMA
Glaucoma is a group of diseases that damage the optic nerve resulting in loss of vision or even blindness, often (but certainly not always) accompanied by an increase in intra-ocular pressure. It is the second leading cause of blindness in the world, affecting an estimated 65 million people worldwide. The disease is usually painless, and (like diabetic retinopathy, see below) often very advanced before the patient starts to notice changes in their vision. This is one reason we stress the importance of annual eye exams.
Anyone can develop glaucoma, but primary risk factors include:
Race/African Americans. Glaucoma is 5-8 times more common in this population than in Caucasians, and is the leading cause of blindness among this group.
Age. Definitely more common after age 60, especially in the Mexican population.
Family History. 7% more risk if a family member has the disease, jumping to near 15% if that family member is a sibling.
Steroid Users. This includes prescribed steroids for diseases like arthritis or asthma.
History of Ocular Trauma.
History of hypertension and/or diabetes.
High myopia (nearsightedness).
There are basically three things I will look at to determine the presence or absence of glaucoma: the intra-ocular pressure (IOP), the appearance of the optic nerves, and the Visual Field. Pressure we do not weight as heavily as we used to; we have learned that some patients will have an IOP within the expected range of normal, yet still have the disease (and we still do not know why the optic nerve is being damaged in the presence of a normal pressure). This is called normal tension glaucoma – and can be more difficult to treat, since most treatment modalities focus upon lowering the pressure.
The optic nerve looks a bit like a donut when it enters the back of the eye. The outer circumference of the donut encapsulates the optic disk; the hole in the donut is called the optic cup. What we generally see as glaucoma progresses is an enlarging of the donut hole. So, patients with the disease often have a larger-than-average optic cup or perhaps a different cup size in one eye versus the other. The Visual Field maps out each eye’s field of view, from extreme periphery in to center. There are very typical losses we will see in early glaucoma as opposed to a normal field – usually losses from the outside going in. This test is still considered the “gold standard” to determine if the disease is present, and is quite simple and painless to administer.
There are two main types of disease: primary open angle glaucoma (POAG) and angle closure glaucoma. In the healthy eye, fluid moves through the pupil and drains from the eye in the angle formed between the iris and cornea (see diagram below in the Macular Degeneration article). In POAG (the most common type), the angle is not physically blocked, but the drainage canals that begin there are “clogged” deeper along their course, usually raising the pressure in the eye. This form progresses more slowly, causes a gradual loss of vision, and responds well to medication. Angle closure glaucoma (or narrow angle glaucoma) is much more rare and is considered a medical emergency – the pressure rises quickly and significantly, and ocular pain and nausea accompany halos and blurred vision. This situation is caused by the pupil dilating slightly and the iris edges “bunching up” and blocking the angle.
Glaucoma can also occur as the result of something else, be it injury, other systemic disease, or even cataract formation. These are called the secondary glaucomas, and a few are listed below:
Traumatic glaucoma. Caused by damage to the ocular anatomy; can occur immediately after the trauma or years later.
Pigmentary glaucoma. Caused by pigment shedding from the rear of the iris; the pigment collects in the drainage canals and clogs them, raising pressure. Must be distinguished from the more common pigment dispersion syndrome, where pigment is shedding but glaucoma is not present.
Neovascular glaucoma. Caused by abnormal new blood vessel growth across the iris and/or into the angle. Associated with a pre-existing problem like diabetes or retinal vein occlusion. Very difficult to treat.
Pseudoexfoliative glaucoma. Much like pigmentary glaucoma except the blocked drainage comes from a flaky material peeling off the anterior surface of the lens.
Treatment options include medication (eyedrops) and surgery. The current trend with medications is toward drugs with better pressure-lowering ability without such significant systemic side effects. Again, the medications are aimed at lowering the intra-ocular pressure, either by decreasing the amount of fluid made in the eye or by increasing the outflow of fluid from the eye. Most surgical procedures are considered after it becomes clear the disease is not well-controlled with medication, and are aimed at increasing the outflow of fluid from the eye.
There are three important points to remember: the disease is generally painless (there are virtually no symptoms), glaucoma is never cured (i.e., treatment and monitoring never stop), and treatment in the form of medication and/or surgery is usually effective in halting further vision loss (detection is key).
Diabetes
and the Eyes
Diabetes is a disease in which the body either does not produce or properly
use insulin. Insulin is a hormone necessary to convert sugar, starches, and
other food into energy needed by the body. The disease affects approximately
17 million people in the United States, a third of which are unaware of its
presence. Both Type 1 and Type 2 diabetics are at risk for vision loss.
Between 40-45% of Americans diagnosed with diabetes have some stage of diabetic retinopathy. Each year 12,000 to 24,000 Americans lose their sight from the disease. It is the leading cause of new blindness in U.S. adults.
The retina is the innermost layer of the eye, and is composed of millions of tiny nerve fibers connected at one end to the optic nerve, and at the other to the retinal receptors. This "neural layer" is nourished by very small blood vessels which help keep everything functioning smoothly. The blood sugar imbalance inherent with diabetes can cause a weakening of the blood vessel walls and a subsequent seeping of fluid or blood into the retina. As areas of the retina swell, the tissue in those areas can die, initially causing a loss of vision in just those particular locations. As you can imagine, progression of leakage leads to progressive swelling, which leads to further loss of vision. Diabetic retinopathy is usually severe before the patient notices the visual changes.
It is ABSOLUTELY ESSENTIAL that diabetics have a dilated eye examination ANNUALLY. This involves placing eyedrops into the eyes to make the pupil larger and affords us a much better view of the retina. We look for any leaking blood vessels, retinal or macular swelling, telltale fatty deposits in the retina, and damaged nerve tissue. We also look for the presence of glaucoma or cataracts, the incidence of which is significantly higher in diabetics.
Scatter
laser surgery can slow or even prevent progression of retinopathy. The name
of the game with diabetic retinopathy is similar to that of glaucoma: PREVENT
FURTHER DAMAGE. There is no "cure" as of this writing. Treatment
of diabetic retinopathy, though still a challenge, continues to improve in
its effectiveness. The true challenge lies in detection - not so much because
detection is difficult, but more so because many diabetic patients are not
aware of the potential eye problems. They simply do not come in for eye exams.
One last important point: the potential for eye problems with diabetes can
be lessened dramatically with good blood sugar control.
Macular Degeneration and Vitamin
Supplements
The macula is the area of our retina responsible for central vision
- it has a much higher concentration of receptors than the peripheral
retina.
Age-related
macular degeneration (AMD) is a condition in which the macula is
damaged, causing a distortion or even loss of central vision. It is the
most
common cause of severe vision loss among people over 65.
There are two types: the dry form and the wet form. Dry AMD is
by far the most common, and occurs when the receptors in the macula
begin
to slowly
break
down. Yellowish deposits called "drusen" can be seen in the area.
Vision loss can be significant, but usually less so than with wet AMD. In
the wet form, abnormal and fragile vessels grow under the macula. The vessels
leak blood and fluid, causing rapid and severe damage to the macula. Vision
loss is usually devastating. Additionally, there are three stages to AMD:
Early, Intermediate, and Advanced. Any form of wet AMD is considered "Advanced," and
the dry form can progress to the wet form.
There is exciting news about
a recent clinical
study linking the use of antioxidant vitamins and zinc with a decreased
risk of progression to advanced AMD.
In October 2001 the National Eye Institute (NEI) published a study
showing that high levels of antioxidants and zinc reduce the risk
of advanced
AMD and its associated vision loss by 25-28%. The nutrients evaluated
by the
researchers
contained:
Vitamin A (beta-carotene) 15 mg
Vitamin C 500 mg
Vitamin E 400 IU
Zinc oxide 80 mg
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Copper
was added to prevent copper deficiency, which may be associated with high levels
of zinc supplementation.
The benefits of the nutrients were seen only in people who began the
study at high risk for developing advanced AMD - those with intermediate
AMD in one or
both eyes, and those with advanced AMD in one eye only. It should be noted
that the high concentrations of the antioxidants used in the study
can not be obtained
from a normal diet, or even most daily multivitamins. Be sure to review
all your vitamin supplements with your family doctor - for example,
smokers should
avoid beta-carotene supplements, as they increase the risk for lung cancer.
Lutein (a carotenoid) has also been linked to a reduced risk for AMD,
but the jury is still out. New studies are underway. However, most
eye care
practitioners
are recommending a combination supplement program of the antioxidants
(Vitamins A, C, and E), zinc, and lutein.
Macular degeneration can occur during middle age. The risk increases
with aging. Other risk factors include smoking, obesity, race (more
prevalent in whites),
family history of AMD, and gender (more common in women).
If you have a family history of macular degeneration, or have been
diagnosed with moderate AMD in one or both eyes (or advanced AMD in
one eye), do
yourself
a favor - get your eyes checked annually, and be sure to ask your doctor
if use of these supplements is right for you!
THEIR
FIRST EYE EXAM
Many parents ask us "How old should my child be when they get their first
examination?" A good rule of thumb is the summer before they begin kindergarten
or first grade, provided you are not noticing anything suspicious that a problem
exists earlier than that (for example: an eye turn, squinting, holding reading
material close in, frequent headaches).
It is important to note that many kids with problems may pass some school
screenings. They could be significantly far-sighted and still pass a distance
acuity test. A far-sighted child may have problems with reading comprehension.
What is really a vision problem can masquerade as a learning disability.
CORRECTION OPTIONS
The only realistic option for children under twelve is spectacles. Contact
lenses require a greater level of maturity. There are many stylish frame designs
available with kids in mind.
WHAT IS AMBLYOPIA?
Amblyopia, or "lazy eye," is generally a condition in which one
eye does not see as well as the other, but not because of the presence of
disease. Usually one eye is turning, and the brain is ignoring it to avoid
double vision, or the prescription in one eye is significantly worse than
the other.
The brain learns to "talk to" the eyes by age seven or eight. If
we can catch the problem before then (and correct it), amblyopia can be avoided.
The child may not be aware of the problem since the good eye "takes over"
for them, or dominates.