by Maureen Duffy
Researchers from the National Eye Institute and New York University have published new research that implicates the normally beneficial and protective "trash-collecting" central nervous system cells in the accelerated cell death associated with retinitis pigmentosa.
Please note that this research is in its earliest stages and has been conducted thus far only with laboratory mice. However, a new clinical trial related to this study, Oral Minocycline in Treating Bilateral Cystoid Macular Edema Associated with Retinitis Pigmentosa, is now underway and is recruiting human subjects.
The research, entitled Microglial phagocytosis of living photoreceptors contributes to inherited retinal degeneration (explained below) has been published in the July 2, 2015 Early Edition of EMBO Molecular Medicine. Molecular Medicine is a peer-reviewed, online open-access journal dedicated to forging new links between clinicians and molecular biologists. Interest areas covered by the journal include aging, angiogenesis, genetics, gene therapy, stem cells, and regenerative medicine.
The authors are Lian Zhao, Matthew K. Zabel, Xu Wang, Wenxin Ma, Parth Shah, Robert N. Fariss, Haohua Qian, Christopher N. Parkhurst, Wen-Biao Gan, and Wai T. Wong, who represent the following institutions: National Eye Institute, National Institutes of Health; and New York University School of Medicine.
Some Terminology to Begin
Here is a brief explanation of the key scientific terms used by the researchers:
- Microglia: Cells in the central nervous system that function as "scavengers" to attack, ingest, and destroy foreign substances and protect the central nervous system against infection. They act as phagocytes of waste products of the central nervous system.
- Phagocytes: A type of cell within the body that engulfs, ingests, and destroys foreign particles, bacteria, and cell debris.
- Phagocytosis: The process by which the cell (phagocyte) engulfs, ingests, and destroys foreign particles. Phagocytosis is a normal process in healthy nervous system tissues and is a key way to clear away dead cells and cellular debris.
About Retinitis Pigmentosa
Retinitis pigmentosa (RP) is part of a large group of hereditary retinal conditions or dystrophies, involving one or several layers of the retina. RP occurs in approximately 1 in 4,000 people in the United States. At present, there is no cure.
Most persons with RP initially experience difficulty with night vision and in low light levels. Central (straight ahead) vision is usually retained until late in the course of the disease, while peripheral (or side) vision becomes progressively more constricted, resulting in "tunnel vision" (pictured above).
Primarily, the retinal rod cells – light-sensitive, specialized retinal receptor cells that activate at low light levels and provide night vision – are involved, but there may also be some involvement of the retinal cone cells, which function best in relatively bright light and provide color vision and greater visual acuity than do rod cells.
About the Research
Excerpted from In blinding eye disease, trash-collecting cells go awry, accelerate damage, via Medical Xpress:
Spider-like cells inside the brain, spinal cord, and eye hunt for invaders, capturing and then devouring them. These cells, called microglia, often play a beneficial role by helping to clear trash and protect the central nervous system against infection. But a new study shows that they also accelerate damage wrought by blinding eye disorders, such as retinitis pigmentosa.
Retinitis pigmentosa damages the retina, the light-sensitive tissue at the back of the eye. Research has shown links between retinitis pigmentosa and several mutations in genes for photoreceptors, the cells in the retina that convert light into electrical signals that are sent to the brain via the optic nerve. In the early stages of the disease, rod photoreceptors, which enable us to see in low light, are lost, causing night blindness. As the disease progresses, cone photoreceptors, which are needed for sharp vision and seeing colors, can also die off, eventually leading to complete blindness.
[The research team] studied mice with a mutation in a gene that can also cause retinitis pigmentosa in people. The researchers observed in these mice that very early in the disease process, the microglia [i.e., the trash-devouring cells] infiltrate a layer of the retina near the photoreceptors where they don't usually venture. The microglia then create a cup-like structure over a single photoreceptor, surrounding it to ingest it in a process called phagocytosis.
Phagocytosis is a normal process in healthy tissues and is a key way of clearing away dead cells and cellular debris. However, in retinitis pigmentosa, the researchers found that the microglia target damaged living photoreceptors, in addition to dead ones.
To confirm that microglia contribute to the degeneration process, the researchers genetically eliminated the microglia, which slowed the rate of rod photoreceptor death and the loss of visual function in the mice. The microglia seem to ignore cone photoreceptors, which fits with the known early course of retinitis pigmentosa.
What triggers microglia to go on this destructive feeding frenzy? [Lead researcher] Wong and colleagues found evidence that photoreceptors carrying mutations undergo physiological stress. The stress then triggers them to secrete chemicals dubbed "find me" signals, which is like ringing a dinner bell that attracts microglia into the retinal layer.
Once there, the microglia probe the photoreceptors repeatedly, exposing themselves to "eat me" signals, which then trigger phagocytosis. In response to all the feasting, the microglia become activated. That is, they send out their own signals to call other microglia to the scene and they release substances that promote inflammation.
More about the Research from Molecular Medicine
From the article synopsis, with the full open-access article available online:
- In retinitis pigmentosa (RP), retinal microglia are shown to potentiate the rate of rod photoreceptor death via phagocytic and pro-inflammatory mechanisms. This process may be common to multiple genetic etiologies of RP in mouse models and in human patients.
- Microglial phagocytosis of rod photoreceptors was initiated at the start of rod apoptosis [i.e., cell death] with early infiltration of retinal microglia into the outer retina, upregulation of phagocytic molecules in microglia, and exposure of PS, an "eat-me" signal, on rod photoreceptors.
- Microglial phagocytosis of rods included apoptotic cells [i.e., cells that have died] but also cells that have not yet been committed to apoptosis and are negative for apoptotic markers, indicating microglial clearance of stressed but living rods.
- Infiltrating microglia demonstrated dynamic interactions with photoreceptors via motile processes that culminate in the overt phagocytosis of non-apoptotic rods.
- The contribution of infiltrating microglia to rod demise was demonstrated by structural and functional rescue of photoreceptor degeneration.
- Microglia-directed interventions may be of potential utility in prolonging the survival of photoreceptors and deferring irreversible vision loss associated with RP of different genetic etiologies.
VisionAware will continue to report on this research as results become available. You can watch a video of microglia "eating" rod photoreceptors at YouTube.
by Maureen Duffy
Audrey Demmitt, RN, BSN, is a nurse diabetic educator, VisionAware Peer Advisor, AFB Career Connect mentor, and author of the VisionAware multi-part blog series on diabetes and diabetes education. At age 25, Audrey was diagnosed with retinitis pigmentosa and continued to work as a nurse for 30 years with her visual impairment.
She has worked as an Adjustment to Blindness Counselor and Diabetic Educator for Vision Rehabilitation Services of Georgia and as a school nurse providing in-service training for school staff and developing care plans for newly-diagnosed students and their families.
In Part 1 of her series, Audrey discussed how diabetes education can help lower your blood sugars and reduce the risk of diabetic retinopathy. In Part 2, she emphasized the significance of the A1C test in the effective diagnosis, treatment, and management of diabetes. In Part 3, Audrey explained the importance and benefits of healthy eating as part of a comprehensive diabetes care plan.
In this month's installment, Audrey discusses the importance and benefits of exercise as a critical component of a comprehensive diabetes care plan. As Audrey says, "Remember this when it comes to exercise: If you are doing nothing, do something. If you are doing something, do more!"
The Importance of Exercise
Exercise is an essential part of the diabetes management plan. There are many benefits to incorporating this healthy habit into your diabetes care. It is an effective way to lower your blood sugars and, over time, lower your A1c. In the long term, regular exercise can protect you against many of the serious complications of diabetes: heart disease, retinopathy, neuropathy, and kidney failure.
According to the American Diabetes Association, regular physical activity:
- lowers blood pressure and cholesterol
- lowers the risk for heart disease and strengthens your heart
- improves blood circulation
- burns calories to help you lose or maintain weight
- increases your energy for daily activities
- helps you sleep better
- relieves stress
- strengthens your muscles and bones
- keeps your joints flexible
- improves your balance to prevent falls
- reduces symptoms of depression
- improves your overall quality of life
Exercise and Blood Sugars
There are two ways that exercise lowers blood sugars:
- When you are exercising, your cells become more sensitive to available insulin, which helps your cells to take up blood glucose during and after the activity.
- When you contract muscles, another mechanism is activated that allows cells to use blood glucose for fuel without the need for insulin.
The American Diabetes Association recommends a combination of aerobic forms of physical activity and strength training for maximum effect:
- Aim for at least 30 minutes of moderate-to-vigorous aerobic exercise five days a week: brisk walking, dancing, and swimming.
- In addition, try to do strength training activities two days a week: using weights, resistance bands, or doing exercises that use your own body weight to work your muscles, such as push-ups or sit-ups.
Safety Tips for Getting Started
- Consult with your doctor before getting started. There may be special considerations and precautions to take if you have known complications, such as heart disease, neuropathy, and visual impairment. You can still exercise, but you may need to adapt your routine. A personal trainer, physical therapist, or vision rehabilitation professional can help you pick safe activities. Your doctor can help you coordinate your exercise plan with your diet and medications.
- Wear a medical alert ID while exercising. You can purchase these IDs at a drugstore or medical supply store or order an ID for free at the Diabetes Research and Wellness Foundation website.
- Start slowly and gradually increase your activity. Begin with a walking program. Try exercising in 10-minute intervals at first. If you are pressed for time, you can do 15 minutes in the morning and 15 minutes in the evening. Easing into regular activity helps to avoid injuries and muscle soreness from doing too much too soon.
- To learn how your body responds to exercise, check your blood sugar before, during, and after your activity when first starting a new routine. Ask your doctor what guidelines to follow with respect to your blood sugar levels. Generally, it is safe to exercise when your blood sugar is between 100mg/dl and 250mg/dl. You may need to eat a snack with 15-20 carbohydrates if you are below 100mg/dl. Postpone your workout if your blood sugar is higher than 250mg/dl and monitor your urine for ketones until it returns to a safe range. Exercise can lower your blood sugar for up to several hours after the activity. The harder and longer the workout, the longer it can affect your blood sugar afterward; therefore, check your blood sugars after exercise too. Discuss any patterns of concern with your doctor.
- Be prepared to treat low blood sugar symptoms while exercising. Carry your glucometer and a fast-acting carbohydrate snack to correct a low blood sugar episode. Stop exercising if your blood sugar is 70mg/dl or below or you feel shaky, weak or confused. Eat 3-4 glucose tabs, ½ cup fruit juice or 5 hard candies to raise your blood sugar and recheck in 15 minutes. Repeat as needed. You can resume your workout once your blood sugar returns to a safe range. For more information, see Hypoglycemia and the 15/15 Rule and Watch for Symptoms of Low Blood Sugar.
- Keep a routine with meals, exercise and medication times. Maintaining consistency can help control your blood sugars and prevent highs and lows.
- Work out with a friend who knows you have diabetes. Be sure your friend knows what to do if you have symptoms of low blood sugar. The buddy system will also help keep you encouraged and motivated.
- Wear clean socks and well-fitting shoes that match the activity. Be sure to check your feet for irritations, cuts, blisters or sores when starting an exercise routine. To avoid serious infections, wash your feet daily and report any new foot problems to your doctor.
- Drink water before, during and after exercise to maintain hydration. Dehydration can cause your blood sugar levels to rise. Drinking water can bring blood sugar down when it is elevated.
- If you experience sudden pain, stop what you are doing. Some muscle soreness can be expected, but pain is not normal. Pain is your body's way of warning you that something is wrong. If a movement hurts, don't do it. If you experience chest pain, shortness of breath, or other cardiac symptoms, call 911 immediately. Carry your cell phone for emergencies while exercising.
- Have fun with fitness and enjoy the benefits. Remember, when it comes to exercise, "If you are doing nothing, do something. If you are doing something, do more!"
New Research: The Argus II Retinal Prosthesis (Bionic Eye) Is Safe, Effective, and Improves Visual FunctionPosted on 6/25/2015 at 3:18 PM
by Maureen Duffy
New clinical trial results from the Argus II Study Group, an international consortium of eye and vision researchers, confirm that the Argus II, also called the "bionic eye," is a safe, reliable, and effective device that "significantly improves visual function and quality of life for people blinded by retinitis pigmentosa."
The latest research, entitled Long-Term Results from an Epiretinal [i.e, "on," "upon," "near," or "against" the retina] Prosthesis to Restore Sight to the Blind, has been published online ahead of print, as an open-source article in the July 2015 edition of Ophthalmology, the official journal of the American Academy of Ophthalmology. Ophthalmology publishes original, peer-reviewed research in ophthalmology, including new diagnostic and surgical techniques, the latest drug findings, and results of clinical trials.
The authors are Allen C. Ho, MD; Mark S. Humayun, MD, PhD; Jessy D. Dorn, PhD; Lyndon da Cruz, MD; Gislin Dagnelie, PhD; James Handa, MD; Pierre-Olivier Barale, MD; José-Alain Sahel, MD; Paulo E. Stanga, MD; Farhad Hafezi, MD, PhD; Avinoam B. Safran, MD; Joel Salzmann, MD; Arturo Santos, MD, PhD; David Birch, PhD; Rand Spencer, MD; Artur V. Cideciyan, PhD; Eugene de Juan, MD; Jacque L. Duncan, MD; Dean Eliott, MD; Amani Fawzi, MD; Lisa C. Olmos de Koo, MD; Gary C. Brown, MD; Julia A. Haller, MD; Carl D. Regillo, MD; Lucian V. Del Priore, MD; Aries Arditi, PhD; Duane R. Geruschat, PhD; and Robert J. Greenberg, MD, PhD. All authors are members of the Argus II Study Group.
Some Background on the Argus II
The Argus II was developed by Second Sight Medical Products, Inc., of Lausanne, Switzerland and Sylmar, California to treat adults with severe to profound retinitis pigmentosa (RP). RP is a rare, inherited degenerative disease that damages light-sensitive cells in the retina, resulting in decreased vision at night or in low light; loss of side (peripheral) vision; and loss of central vision as the disease progresses. At present, there is no cure for RP.
The retina is the light-sensitive tissue that lines the inside surface of the eye. Cells in the retinal tissue convert incoming light into electrical impulses. These electrical impulses are carried by the optic nerve to the brain, which finally interprets them as visual images. The Argus II is not a cure for RP; instead, it is intended to replace the function of the light-sensing cells that have been damaged and/or degraded by the disease.
The Argus II device consists of the following components:
- a small video camera
- a transmitter mounted on a pair of eyeglasses
- a video processing unit (VPU)
- an artificial retina (the implanted retinal prosthesis, which is an array of electrodes)
The video camera images are transformed into electronic data by the VPU that sends signals to a wireless receiver implanted in the eye (the retinal prosthesis electrodes). The electrodes allow the electronic signals to bypass the damaged retina and transmit directly to the brain, where they are interpreted as visual images.
The cost of the Argus II is approximately $100,000; additional fees include the implantation surgery and training to use the device. The Second Site website provides an illustrated system overview, including a video animation.
On February 14, 2013, Second Sight received approval as a Humanitarian Use Device (HUD) from the U.S. Food and Drug Administration (FDA) for the Argus II. The HUD designation is an approval specifically for devices intended to benefit small populations and/or rare conditions. On August 15, 2013, Second Sight announced that the Argus II was approved by the Centers for Medicare and Medicaid Services (CMS), beginning October 1, 2013. You can learn about all ongoing Argus® II clinical trials at the ClinialTrials.gov website.
Who Is Eligible for the Argus II?
The Argus II is implanted in a single eye, typically the worse-seeing eye. It is indicated for persons with severe to profound RP who meet the following criteria:
- Age 25 or older
- Have bare light or no light perception in both eyes: Bare light perception is the ability to perceive light, but not the direction from which the light is coming. If the person has no residual light perception, then evidence of intact inner layer retina function must be confirmed.
- A previous history of useful form vision
- Be aphakic or pseudophakic: Aphakic means that the eye is lacking its natural lens. Pseudophakic means that the eye has been fitted with an artificial lens implant (as in cataract surgery) to replace the missing or surgically removed natural lens.
- If the person is phakic (i.e., has a natural lens or an artificial lens implant) prior to the Argus II implant surgery, the lens will be removed during the implant procedure.
- Be willing and able to receive the recommended post-implant clinical follow-up, device fitting, and visual rehabilitation.
About the Latest Argus II Research
Excerpted from Bionic eye clinical trial results show long-term safety, efficacy, of vision-restoring implant, via Medical Xpress:
The latest three-year clinical trial results of the retinal implant, popularly known as the "bionic eye," have proven the long-term efficacy, safety and reliability of the device that restores vision in those blinded by a rare, degenerative eye disease. The findings show that the Argus II significantly improves visual function and quality of life for people blinded by retinitis pigmentosa.
To further evaluate the safety, reliability and benefit of the device, a clinical trial of 30 people, aged 28 to 77, was conducted in the United States and Europe. All of the study participants had little or no light perception in both eyes.
The researchers conducted visual function tests using both a computer screen and real-world conditions, including finding and touching a door and identifying and following a line on the ground.
A Functional Low-vision Observer Rated Assessment (FLORA) was also performed by independent visual rehabilitation experts at the request of the FDA to assess the impact of the Argus II system on the subjects' everyday lives, including extensive interviews and tasks performed around the home.
The visual function results indicated that up to 89 percent of the subjects performed significantly better with the device. The FLORA found that among the subjects, 80 percent received benefit from the system when considering both functional vision and patient-reported quality of life, and no subjects were affected negatively.
After one year, two-thirds of the subjects had not experienced device- or surgery-related serious adverse events. After three years, there were no device failures. Throughout the three years, 11 subjects experienced serious adverse events, most of which occurred soon after implantation and were successfully treated. One of these treatments, however, was to remove the device due to recurring erosion after the suture tab on the device became damaged.
More about the Study from Ophthalmology
From the article abstract, with the full open-access article (PDF) available online:
Purpose: Retinitis pigmentosa (RP) is a group of inherited retinal degenerations leading to blindness due to photoreceptor loss. Retinitis pigmentosa is a rare disease, affecting only approximately 100,000 people in the United States. There is no cure and no approved medical therapy to slow or reverse RP.
The purpose of this clinical trial was to evaluate the safety, reliability, and benefit of the Argus II Retinal Prosthesis System in restoring some visual function to subjects completely blind from RP. We report clinical trial results at one and three years after implantation.
Participants: There were 30 subjects in 10 centers in the United States and Europe. Subjects served as their own controls, that is, implanted eye versus fellow eye, and "system on" versus "system off" (native residual vision).
Methods: The Argus II System was implanted on and in a single eye (typically the worse-seeing eye) of blind subjects. Subjects wore glasses mounted with a small camera and a video processor that converted images into stimulation patterns sent to the electrode array on the retina.
Main Outcome Measures: The primary outcome measures were safety (the number, seriousness, and relatedness of adverse events) and visual function, as measured by three computer-based, objective tests.
Results: A total of 29 of 30 subjects had functioning Argus II Systems implants three years after implantation. Eleven subjects experienced a total of 23 serious device- or surgery-related adverse events. All were treated with standard ophthalmic care. As a group, subjects performed significantly better with the system on than off on all visual function tests and functional vision assessments.
Conclusions: The three-year results of the Argus II trial support the long-term safety profile and benefit of the Argus II System for patients blind from RP. Earlier results from this trial were used to gain approval of the Argus II by the Food and Drug Administration and a CE mark in Europe. The Argus II System is the first and only retinal implant to have both approvals.
VisionAware will continue to report Argus II research updates as they become available.
Additional Argus II Information at VisionAware
- The Argus II: Fact or Science Fiction? A "Bionic Eye" Pioneer Tells Her Story
- New European Research: Is the Argus II (the "Bionic Eye") Cost-Effective?
- The Argus II Retinal Prosthesis ("Bionic Eye") Receives Medicare Approval
- Meet Aries Arditi, Ph.D., Founder and Principal Scientist of Visibility Metrics, LLC
- Meet Duane Geruschat, Ph.D. and the Argus II Retinal Prosthesis at Second Sight Medical Products
Argus II images provided by Second Sight Medical Products, Inc. Used with permission.
by Maureen Duffy
Guest blogger Priscilla Rogers, Ph.D. is the Program Manager for VisionAware and co-author of Aging and Vision Loss: A Handbook for Families. Her other works include Self-Advocacy Skills Training for Older Individuals Who Are Visually Impaired and Solutions for Success: A Training Manual for Working with Older People Who Are Visually Impaired. She has an M.A. degree in gerontology and a Ph.D. in special education with an emphasis in vision and aging.
The 2015 White House Conference on Aging
The White House Conference on Aging (WHCoA) is a once-a-decade conference, sponsored by the Executive Office of the President of the United States, that makes policy recommendations to the president and Congress focusing on the needs of older Americans. 2015 is an especially critical year for the WHCoA, with the convergence of the 50th anniversary of the Older Americans Act, the 25th anniversary of the Americans with Disabilities Act, and the 50th anniversary of Medicare and Medicaid!
These programs are critical to older Americans with vision loss. Almost 50 percent of Americans over 64 reported some level of disability in the 2010 census, with over 13.5 percent reporting difficulty seeing.
However, according to the input the American Foundation for the Blind (AFB) received in our recent online survey and national conversation at our 2015 Leadership Conference, it is clear that older Americans with vision loss are not receiving the rehabilitation or support services needed to maintain independent lifestyles or, in some cases, to meet the most basic of everyday needs.
Major Issues Identified
Here are some of the major issues that have emerged from our initiatives :
- The primary health programs serving older Americans, Medicare and Medicaid, do not cover technology and specialized services (e.g. low vision services and vision rehabilitation services) for older Americans who are blind or visually impaired. A comprehensive reevaluation of systems serving older Americans should ensure fiscal support, coordination of research, and dissemination of services and assistive technology to enhance independence and quality of life for persons who develop vision loss at any stage of life.
- Funding for specialized services for older adults with vision loss is insufficient. Important services do not reach many of those who have the greatest need of assistance – including those in rural areas, those who are isolated from social and family networks, and those who have additional disabilities and medical conditions (especially deafness/hearing loss, memory loss, and diabetes). At a minimum, full funding is needed for the Older Individuals Who Are Blind (OIB) program, a federal program authorized by the Vocational Rehabilitation Act and administered through vocational rehabilitation services in each state.
- The number of qualified professionals providing supports for adults with vision loss is vastly inadequate to meet the service delivery needs of the growing population of older Americans with vision loss. Targeted funds are needed to support training and employment of vision professionals, as well as to provide pre-service and in-service training for service providers, caregivers, and health-care workers who provide in-home, community-based, and residential services.
- Older Americans with vision loss can continue to live independent and fulfilling lives if given access to appropriate home and community-based supports for carrying out everyday tasks. Seniors should have access to qualified, trusted assistance for reviewing printed materials and managing finances in a way which respects their independence and privacy. Additionally, all Americans – particularly seniors – benefit from affordable, reliable public transportation access, not only for medical appointments and groceries, but for social activities, visiting family, and pursuing their retirement goals and aspirations.
- Economic security is even more precarious among older Americans who are likely to have had fewer employment opportunities or to have retired early due to unexpected vision loss. These individuals significantly economically disadvantaged as a direct result of their vision loss. Title V of the Older Americans Act should be amended to require that programs funded through Title V provide assistance to these individuals, regardless of income status.
- One respondent shared the following economic observations with AFB: "Many individuals were diagnosed after retirement and did not even think about planning to have finances to pay for video magnifiers; co-payments for injections related to macular degeneration; in-home assistance; or options for transportation. Those who do not have the financial resources do without; those who have financial resources found that retirement funds have to be diverted from more fun/social expenditures to 'eye care needs.'"
What Can You Do To Help?
AFB is looking for organizations to sign on to our advocacy letter to the President of the United States. To participate, review the letter and the report and email your organizational signature to AFB in care of Rsheffield@afb.net. We need your support by the close of business on June 25, 2015.
Remember, only organizations can sign on to this letter. However, individuals are urged to write their own letters and/or participate in the following ways:
- VisionAware invites you to a "virtual watching party" of the White House Conference on Aging on July 13, 2015. From the comfort of your office or home, you can participate live in a once-every-decade event by visiting the White House Conference on Aging website and following the instructions for participating.
- On the WHCoA website, you can learn how you can take part in the StoryCorps project, share consumer stories, and read/respond to policy briefs.
- You can also post your comments on our Facebook page to engage in conversation with VisionAware followers.
- Use the #WHCOA hashtag on your social media postings.
Read Other Posts about the White House Conference on Aging
by Maureen Duffy
Editor's note: One of the many benefits associated with an online information center and website, such as VisionAware, is the ability to track readers' search terms [i.e., information readers are seeking as they search the Internet]. Since the earliest days of VisionAware.org, the following questions about cataracts and cataract surgery consistently rank within the top ten searches and are especially relevant during Cataract Awareness Month:
- Is it true that cataract surgery now can be performed entirely by laser?
- How can I find out more about laser surgery for cataracts?
An Answer from Tina D. Turner, M.D.
This week, our answer comes from Tina D. Turner, M.D., a staff comprehensive ophthalmologist at Henry Ford Health System's Grosse Pointe Ophthalmology and author of An Introduction to Cataracts and Cataract Surgery on the VisionAware website. She lectures widely on many topics in ophthalmology to ophthalmology residents, family medicine residents, emergency medicine residents, ophthalmic technicians, surgical technicians, and patients.
Performing Cataract Surgery
Most cataracts are highly treatable. Cataract surgery is one of the most common surgeries performed in the United States, with approximately 98% of patients experiencing improved vision if there are no other eye conditions present.
Two very small incisions (one larger, approximately three millimeters, or one-tenth of an inch, and one smaller, approximately one millimeter, or one thirty-second of an inch) are made in the cornea, which is the transparent dome-shaped tissue that covers the front part of the eye. A thick, sticky, glue-like material (called "viscous") is injected into the front part of the eye to help maintain its shape during surgery. This material is made from substances that occur naturally in the body. Because it is thick, this material will not leak out of the incisions during surgery.
The surgeon creates an opening in the natural "sac" or "bag" that holds the lens in place, called the lens capsule. The lens is separated from the lens capsule by using a balanced salt solution.
Once the capsule is open and the lens can move freely inside the capsule, a special ultrasound device is used to break the lens into small pieces and suck it out of the eye. This technique is called phacoemulsification.
Prior to the development of phacoemulsification, the lens used to be removed in one solid piece through a very large incision (8-12 millimeters). That surgery entailed considerably more risk and had a significantly longer recovery time.
After the lens is removed, additional viscous material is injected into the lens capsule to hold it open and make room for the new artificial lens. The folded artificial lens is inserted into the "sac" or capsule, where it is then allowed to unfold.
The viscous material that maintained the shape of the eye during surgery is removed. The two incisions usually self-seal and do not require stitches.
Phacoemulsification was introduced more than 40 years ago and is now the most common method surgical method used to remove cataracts.
The Femtosecond Laser Does not Take the Place of Manual Cataract Surgery
The role of lasers in the removal of cataracts is beginning to unfold in the United States. Femtosecond lasers have been used in ophthalmic surgery since 2001, and in the late 2000s, work began on their use in cataract surgery.
In 2008, the first laser-assisted cataract surgery was performed in Hungary. After gaining FDA approval, the first laser-assisted cataract surgery was performed in the United States in 2010. Since that time, it has been gaining acceptance and popularity.
The laser does not take the place of manual cataract surgery; instead, the laser "assists" in the removal of the cataract. Phacoemulsification is still used to remove the cataract itself.
The laser performs three key steps in the cataract surgery procedure:
- the corneal incisions
- opening of the capsule containing the cataract
- the initial sectioning of the cataract into smaller pieces.
It performs these three steps with incredible precision, and it is this aspect that may prove it to be superior to the current technique in which these steps are manually performed by the surgeon. The laser can also be used to make incisions in the cornea to treat certain types and amounts of astigmatism.
Further data and well-designed studies are needed to prove that this method is associated with better outcomes and fewer complications than phacoemulsification alone, and much work is being done on this front.
Because insurance does not cover the cost of having laser-assisted cataract surgery, patients are required to contribute a significant out-of-pocket payment. It is important to discuss with your physician what type of procedure would be best for you.
Additional Information about Cataracts
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