Prevent Blindness America has declared February as “Age-Related Macular Degeneration Awareness Month.” Making the diagnosis of macular degeneration is usually very straightforward and is based upon your age, your vision and the appearance of your retina.
The “Age-Related” in Macular Degeneration
Age related macular degeneration, or ARMD, certainly increases in prevalence as we get older, that is, the number individuals affected increases as we age. BUT, this does not mean we are all destined to get the disease.
Overall, I hesitate to diagnose the disease in patients less than 55 years old. Can a 50 year old have the disease? Certainly, but not a 20 year old (they must have something different).
So, there is an age requirement: age > 55.
Your Vision Must be Affected
By definition, the disease is a bilateral (affects both eyes) and causes degeneration of the macula and, thus, decreased central sight.
When your vision is tested with the “Snellen” chart (that’s the chart that starts with the big “E” at the top), we are testing only how well your macula functions (as opposed to peripheral sight).
If you your vision is 20/20, it’s hard to say you have any loss of vision caused by a disease.
The examination of your retina is a key to diagnosing macular degeneration. There are characteristic changes in the appearance of your retina that identify certain patients with macular degeneration.
To diagnose ARMD, I look for pigmentary changes, drusen, loss of pigment, fluid, blood, etc., to make the diagnosis. Often, I perform a fluorescein angiogram to aid in the diagnosis.
What Does This Mean?
Well, in a nutshell, this means that it is usually pretty easy to diagnose patients with macular degeneration. Sometimes the diagnosis is difficult, say when the retina appears to have the disease, but the vision is normal.
I get comments all the time about patients who have drusen and wondering if they have, or will have, macular degeneration.
There are two conditions where laser treatment is needed in patients with diabetic retinopathy: macular edema and evidence of proliferative retinopathy. In cases where macular edema, swelling of the retina in the macular area, is present, “focal” photocoagulation is needed. In cases of proliferative diabetic retinopathy, “pan-retinal photocoagulation,” or PRP, is needed.
Focal Laser —> Diabetic Macular Edema
PRP —> Proliferative Diabetic Retinopathy
Focal Laser and Diabetic Macular Edema
If you remember, this is the most common stage of diabetic retinopathy. Almost every patient with diabetic retinopathy develops some leakage in the macula, potentially causing decreased vision. The normal retinal blood vessels develop tiny little blebs along the blood vessel walls. Theses outpouchings are called “microaneurysms.” We know, and can prove, using fluorescein angiography, that these microaneurysms leak both blood and the clear, fluid part of blood. “Focal” laser is presently the treatment of choice for diabetic macular edema.
A small lens is placed on the surface of the eye. The laser does not hurt, is performed in the office and takes less than 10-15 minutes. The idea is to treat the microaneurysms near the macula, but not the actual macula. Treating the actual macula will cause permanent blind spots in your vision (not good).
It may take several months to determine if the laser was successful. There is no care needed after the laser is performed. It will most likely need to be repeated some day.
Treating the leaky microaneurysms is like weeding a garden, new areas will crop up.
Pan-Retinal Photocoagulation (PRP) is Used to Treat Proliferative Diabetic Retinopathy
Proliferative diabetic retinopathy, or PDR, affects about 10% of patients with diabetic retinopathy and can lead to blindness. Proliferative diabetic retinopathy develops when the retina becomes ischemic. When a tissue is “ischemic,” it is not getting enough oxygen, usually from poor, or insufficient, blood flow.
Ischemia = Oxygen Demand Exceeds Supply
When the retina becomes ischemic, it releases a protein called Vascular Endothelial Growth Factor (VEGF). The vascular endothelial growth factor (VEGF) causes abnormal blood vessels (neovascularization) to develop on the surface of the retina and on other parts of the inside of the eye such as the optic nerve and iris.
Blindness may develop from massive proliferation of the neovascularization (aka abnormal blood vessels) causing either retinal detachment or, a rare type of painful glaucoma (neovascular glaucoma – NOT the regular glaucoma).
In the illustration above, neovascularization has developed on the surface of the retina. These abnormal blood vessels have also broken and bled causing a very small vitreous hemorrhage. This blood may be seen as sudden floaters, or if large enough, may block most of the light from hitting the retina, causing significant loss of vision.
Remember the word ischemia? (Oxygen demand exceeds oxygen supply).
So far, ischemia has caused vascular endothelial growth factor (VEGF) to be liberated. The VEGF has caused neovascularization to develop.
Stop the ischemia, Stop VEGF, Stop the Proliferation
If we laser the peripheral retina, the portion of the retina away from the macula, we can stop the production of VEGF in most cases and arrest the proliferative phase of the diabetic retinopathy.
In effect, we are killing small portions of the peripheral retina with each laser pulse. Since we (scientists and other smart guys) are unable to increase oxygen supply, we must decrease demand. The “ischemia” is over, VEGF production stops and the neovascularization goes away. Disease process halted!
This procedure is also performed in the office. It can be uncomfortable (actually it can hurt!) and I prefer to numb up the entire eye. The procedure can take 30-45 minutes. It make take several weeks to determine if enough laser is performed. It is not uncommon for 1000 pulses or more to be required.
If performed timely, this potentially blinding phase of the disease can be halted!
Most of the “fakes” are confused with macular degeneration due to the presence of choroidal neovascularization, aka the “wet” form of macular degeneration. Remember that in wet macular degeneration, the sine qua non of the diagnosis is the presence of abnormal, neovascular tissue underneath the macula. Symptoms of these other macular diseases all include either fixed grey spots in the vision and/or distortion.
Myopic Degeneration is a condition seen in severely near-sighted individuals. Scarring, similar to that of dry macular degeneration, may develop in the macula and cause some loss of vision. The scarring usually is not too progressive, that is, it moves very, very slowly. At times, choroidal neovascularization may develop in the same way as wet macular degeneration. Treatment options are similar. Patients typically are very near-sighted and younger than the average patient with macular degeneration.
Idiopathic Choroidal Neovascularization. Another condition that occurs in patients younger than 50 years old. The choroidal just develops in an otherwise “normal” looking eye, that is, the macula looks completely normal. There is no scarring, drusen or fluid. There may be associated signs of retinal inflammation.
In this condition, there is sudden, but persistent change of vision developing in a younger patient. Fluorescein angiography demonstrates the presence of choroidal neovascularization. Treatment options include Avastin® (bevacizumab) or other anti-VEGF treatments. Long term follow-up is recommended.
Ocular Histoplasmosis (OHS) is a disease that is transmitted by a fungus (histoplasma capsulatum) found in bird (usually chickens) and bat droppings. The fungus becomes air-borne and gains entry through the lungs. At this point, it may cause cold or flu-like symptoms. A small percentage of patients may go on to develop retinal involvement.
Retinal involvement includes peripheral scarring, also known as “histo spots,” and, guess what, choroidal neovascularization underneath the macula.
Ocular histoplamosis is a leading cause of blindness in the 20-40 year old age group. It is very common in areas such as the Mississippi River Valley. It is not uncommon that a patient has had exposure to chicken farming.
Other, more uncommon causes included choroidal neovascularization due to trauma (choroidal rupture), angioid streaks (seen in pseudoxanthoma elasticum and Ehler’s Danlos Syndrome).
What does this mean? There are several diseases that behave and are treated similar to wet macular degeneration. It is important to note the others develop much younger than typical macular degeneration and have slightly different histories or physical findings. All do have choroidal neovasculization as a common denominator and all probably can be treated with anti-VEGF.
Laser treatment for diabetic macular edema is still the preferred treatment for most patients with diabetic retinopathy. Despite all the recent news about intraocular injections of anti-VEGF and steroid medications, the laser remains the mainstay.
The most common manifestation of diabetic retinopathy is the development of macular edema (also known as diabetic macular edema (DME) or clinically significant macular edema (CSME)). Almost all patients who develop diabetic retinopathy develop some degree of swelling in the macula. The normal retinal blood vessels begin to leak into the surrounding tissue. It is not unlike a “soaker” hose for your lawn. Of all the stages of diabetic retinopathy, this is the most common and does NOT lead to blindness.
The development of swelling, or edema, can decrease the central vision. This is the most common way vision is lost. The surgical goal is to arrest further swelling by treating the retina with laser photocoagulation. The laser treatment is focused on areas of leakage called “microaneurysms” which are the actual incompetent areas in the normal retinal vessels.
Once treated, the macular swelling usually stays the same. About 80% of the time, the macular edema, and vision stabilize! My job is achieve status quo. At times, especially when caught early, the vision improves as the swelling decreases. Rarely, the laser doesn’t work.
The laser used is usually a “hot” laser, that is, it works by transferring heat to the tissue. The procedure is performed in the office setting, takes no longer than a regular office visit and is painless. There is no post-operative care needed.
The result of the laser can take months to assess. I usually will not see a patient back for another 4 monthas or so.
Two types of retinal detachments. One group, called rhegmatogenous retinal detachment, can occur in any one and involves the formation of a tear or hole in the retina. The second group, called traction retinal detachments, involves tissue forming on the surface of the retina and “pulling” the retina to form a detachment. This is the case with diabetic related retinal detachments.
Maintain Your Perspective While Reading! Remember fewer than 0.3% of patients with diabetes now (as of 2007) suffer severe vision loss. Retinal detachment in diabetics is the most common way a diabetic can lose significant vision, including blindness.
There are several stages of diabetic retinopathy. The proliferative phase, by definition, involves the formation of neovascularization (new, abnormal blood vessels) on the surface of the retina. As ivy may creep along the forest floor, these abnormal vessels may creep along the surface of the retina.
At some point the neovascular vessels, reaching from “Point A” to “Point B,” begin to contract, pull up on the retina and cause a retinal detachment. The neovascular vessels cause “traction” on the retinal surface thereby pulling the retina apart.
Retinal Detachments Can Blind. Left untreated, the retinal detachment may spread and eventually detach the macula (the functional center of the retina). The prognosis for restoration of vision is poor when a diabetic retinal detachment involves the macula. This is the basic mechanism by which diabetes may lead to blindness.
Vitrectomy surgery is indicated to literally cut away the offending neovascular complex. Intraocular surgery, also known as a vitrectomy, is required to gently separate the abnormal surface tissue from the underlying retina. If successful, the retina may be reattached and the vision, and retina, becomes stable.
Too often, patients are unaware that a retinal detachment has formed. The macula may be still attached and, though misleading, the vision is still quite useful. Many other times, patients may have lost significant vision in one eye and retain good vision in the other. Believe it or not, many patients are unaware of significant vision loss when only one eye is affected.
Recommendations for diabetic eye exams include routine visits to look for disease while the vision is still good. This stuff is usually preventable and avoidable!
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist
Well, yes. It is always necessary to dilate the pupil for a thorough exam of the retina. A dilated pupillary exam is part of a thorough examination of the eye. Without dilation, it is near impossible to see any structures of the retina through the tiny, 2-3 mm, undilated pupil.
All my patients need to be dilated because I am a retinal specialist. Most of my patients have macular degeneration or diabetic retinopathy. Without dilation I could not examine the retina properly.
As part of the initial screening when a patient arrives at the office, dilating drops are instilled into one or both eyes. The patients are then escorted to a separate “dilating” room. Patients may read, watch TV or talk until dilation occurs. Usually this takes about 15-20 minutes, bur variations do occur. Once the pupils are dilated, patients are then moved to an examination room and we complete the office visit by examination with me, the doctor.
Why do the drops take so long to work? There are a few reasons for the varying times a patient may wait before complete dilation. There are both physiologic reasons and practical reasons.
Physiologic reasons include the patient’s age and the color of their eyes (color of the iris). Young patients with darkly pigmented (e.g. brown eyes) eyes take the longest to dilate. They are slow dilators. Why? The muscles that need to be relaxed by the dilating drops are the strongest at younger ages. Also, the pigment in darkly colored eyes absorbs the dilating medicine and, thus, it takes longer for the medicine to exert its effect.
I don’t discriminate, but the dilating drops do. The corollary to the slow dilator is that blue eyed, older patients do not take much time to dilate at all. Sometimes this may be as fast as 5-10 minutes. You can imagine the nasty looks I sometimes get as I am seeing patients out of turn, simply because some patients dilate faster than others.
There are some diseases or situations where dilation also takes a lot longer than normal. Some patients simply don’t respond well to the drops. Patients with uveitis (inflammation inside the eye) also take a long time to dilate.
Sometimes I cheat by having some of my patients arrive dilated. I don’t suggest this for a routine exam because it is often very difficult to accurately assess vision. After I operate, I usually instill dilating drops in the operating room. Patients arrive to the office, the next day, already dilated. The exam is usually very brief.
There are practical reasons for longer dilating times. Occasionally, doctor’s offices run behind. I try to run my schedule as fast and efficiently as possible, but sometimes we can’t do it. On occasion, we might blame slow dilating for the reason for a longer waiting time. (Ok, don’t quote me on this one or I’ll deny it.)
Others ways to examine the retina are available, but none as good as a dilated exam allowing direct visualization of the retina. Ultrasound may be used to determine if the internal structures are in the right position. A retinal detachment, for example, may be diagnosed by ultrasound.
Non-dilating (so called non-mydriatic) cameras are available. These devices are able to take pretty good pictures of the retina through an undilated pupil. They are quick and used for screening purposes. If an abnormality is seen, then a complete dilated exam is warranted. It is not good enough for the detailed examination required for patients with diabetic retinopathy or macular degeneration.
In conclusion, fully dilated examination is essential to a proper exam of the retina. Other techniques just don’t provide the information we get by directly viewing the retina. It does take a longer time, and at our office we warn each patient about the necessity of dilation.
Thanks for your patience.
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist
This is the first of a small series regarding stem cells and their potential benefits to retinal diseases; principally macular degeneration and retinitis pigmentosa.
As diabetic retinopathy is primarily a disease of blood vessels, i.e.poor blood flow, loss of blood flow, leaking vessels, etc., macular degeneration is actually a disease of one of the layers of the retina. Specifically, the layer affected is called the Retinal Pigment Epithelium (RPE). It is a layer of cells that have numerous functions and responsibilities, one of which is keeping the photoreceptor healthy and happy. Remember photoreceptors are also known as rods and cones.
The retina is a laminated tissue. It lines the inside of the eye in the same way that wallpaper lines the inside of a room. Just underneath the retina is a layer of cells, the Retinal Pigment Epithelium (RPE). The RPE layer is uniformly found underneath the entire retina, even the macula. For us to “see,” the retina must be attached and all the layers of the retina be healthy. This is not so in macular degeneration. While the retina is attached, the RPE layer becomes sick and dysfunctional; it degenerates. It is the RPE layer that is diseased in macular degeneration.
In areas of the macula where the RPE has become dysfunctional, the vision is impaired. Symptoms include blurry vision and distortion. The actual cause of the degeneration of the RPE is not known; it may be due to poor blood supply from a vascular layer deep to the RPE (the choriocapillaris, aka choroid), it may be purely bad genetic programming or it may be due to environmental factors (e.g. sun, smoking, etc.).
How to Replace Damaged Cells? Retinal Pigment Epithelium cells do not reproduce or regenerate. Once the RPE is damaged, the eye can not make more. The focus of research has been, how to replace damaged RPE cells?
Several approaches to replace Retinal Epithelium Cells are under experimentation. Attempts at direct transplantation have had some success. Stem cell transplantation, in theory, seems very promising.
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist
A patient came into the office complaining of new onset distortion in the right eye. My patient, JG, is a 64 year old male, caucasian, and has a long history of smoking. JG started noticing changes in his central vision about 6 weeks ago. At first, there was some distortion in the central vision. When looking out his front window, he noticed that the telephone wires developed an extra “wiggle.” This has been getting worse. He noticed that even small print has become hard to read. Now, when he closes his left eye, he can’t see people’s faces well; they are “missing” an eye and a nose.
What is happening? This is a typical “story” or history of a patient developing wet macular degeneration. The “wet” part means that abnormal blood vessels have developed within the layers of the retina. More specifically, the abnormal blood vessels, aka neovascularization, have developed underneath the macula. These blood vessels can physically damage some of the vital layers within the retina, leak and cause fluid to accumulate and often bleed, although the blood doesn’t really cause any harm.
The macula is the functional center of the retina. It gives us our central vision and this is where we have the best color vision. The rest of the retina gives us our peripheral or “side” vision. The macula is only about 2 X 2 mm large! Any small perturbation in this area may have dramatic consequences to our central vision.
What to do? The first thing to do is to make the proper diagnosis. While this may be a typical scenario, there are a few other conditions that may cause the same or similar complaints. If you can, see a retina specialist and have a flourescein angiogram performed. This dye test is very sensitive and specific for demonstrating neovascularization and estimating macular edema (fluid collection).
What can be done? Treatments these days consist of intraocular injections of Vascular Endothelial Growth Factors (VEFG). These injections neutralize the effects of this hormone which causes growth of the abnormal blood vessels. Avastin®, Lucentis® and Macugen® are commonly used. Your doctor should explain which therapies are available and why. Other treatments may include laser photocoagulation and photodynamic therapy.
In general, the earlier we institute treatment, the better the visual prognosis.
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist
Every diabetic needs to get their eyes dilated once a year to look for diabetic retinopathy. Getting your eyes examined for glasses doesn’t count. Why?
The goal of examining the retina is to detect diabetic retinopathy. Pupillary dilation is the only proper way of examining the retina. With the pupil properly dilated, your eye doctor can examine the entire retina easily and carefully. The retina is the inside lining of the eye. It is the sole tissue in the eye affected by diabetes.
What are we looking for in the eye exam? Basically, we are looking for swelling in the macula and evidence of neovascularization on the retina or other structures of the eye.
Macular edema, or clinically significant macular edema, can blur vision and may need treatment with either laser or intraocular injections such as Avastin® or steroid. Neovascularization of any of the structures is a clear sign of proliferative diabetic retinopathy. Proliferative diabetic retinopathy (PDR) can lead to blindness. Evidence of PDR must be treated with pan-retinal photocoagulation (PRP), an intense array of laser burns to your peripheral retina.
If your eye exam has neither evidence of macular edema nor signs of proliferative diabetic retinopathy, you are considered stable. Depending upon the severity of your disease, you may be asked to return in 6-12 months for re-exam. Next time, we’ll be looking for the same things.
A last note: As I have said many times before, you can not tell if you have diabetic retinopathy as your vision may be normal. Make sure to have regular dilated exams!
In June, the FDA approved a new intraocular device for the treatment of so-called retinal vein occlusions. In this disease, the whole or partial venous tree of the retina becomes occluded. Secondary swelling of the macula occurs thereby reducing vision. Current therapy involves only laser treatment.
This new drug delivery system, marketed by Allergan Pharmaceuticals, will be available later this year. It will involve an in-office injection of the small device right into the eye. Dexamethasone, a well studied steroid, will be released for about 6-9 months. The system, itself, will biodegrade as the drug is released.
The Ozurdex® system was noted to improve vision in up to 30% of patients suffering from RVO.
What does this have to do with diabetic retinopathy? There has been evidence over the past few years that direct injection of steroids was beneficial to patients with RVO. Similarly, there is evidence that steroids also may improve diabetic macular edema AND age related macular degeneration. Doctors, like myself, have been injecting steroids for these entities for several years, using the medications “off-label.” Don’t worry, using medications off-label is legit. In the end, this steroid implant may be a very useful tool to combating macular edema in diabetics! It is just around the corner!
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist
A detached retina is potentially blinding. The retina is the light sensitive tissue that lines the inside of the eye. A retinal tear or hole usually leads to a retinal detachment. Floaters can sometimes be the earliest, and only, symptom. Many times there is little warning and a retinal detachment usually occurs without trauma.
Capital Eye Consultants Randall V. Wong, M.D. Contact: Brigitte O’Brien
A: 3025 Hamaker Court, Suite 101 • Fair fax, Virginia 22031