by Maureen Duffy
Results from a new clinical trial, presented at the July 2014 Alzheimer's Association International Conference, suggest that cataract surgery may slow mental decline in people with Alzheimer's disease and related dementias. Preliminary study results indicate that improved vision, resulting from cataract surgery, can have a variety of benefits – both visual and non-visual – for people with dementia.
The research, entitled Visual and cognitive improvement following cataract surgery in subjects with dementia, funded by the National Institute on Aging, was presented on July 13, 2014, at the Alzheimer's Association International Conference in Copenhagen, Denmark.
The study authors are Alan Lerner; Sara Debanne; Julie Belkin; Jon Lass; Tatiana Riedel; Thomas Steinemann; Susie Sami; and Grover Gilmore, who represent the following institutions: Case Western Reserve University; University Hospitals Case Medical Center; and MetroHealth Medical Center in Cleveland, Ohio.
The Alzheimer's Association International Conference (AAIC) is the world's largest gathering of leading researchers from around the world focused on Alzheimer's and other dementias. As a part of the research program of the Alzheimer's Association, AAIC serves as a catalyst for generating new knowledge about the cause, diagnosis, treatment, and prevention of Alzheimer's disease and related disorders.
About the Research
From For People with Dementia, Cataract Surgery Improves Not Only Vision but Cognition and Quality of Life, via the Alzheimer's Association:
"This study supports the Alzheimer's Association view that people with dementia retain, and benefit from, full healthcare treatment," said Maria Carrillo, Ph.D., Alzheimer's Association vice-president of Medical and Scientific Relations. "Too common attitudes such as, 'There's no need for extra care' or 'Why put them through all of that' are not justified and are bad medical practice."
"Appropriate thoughtfulness and restraint are necessary when considering surgery or other procedures for people with Alzheimer's or another dementia. However, we should not assume that medical procedures cannot be pursued or are too risky. As these new results show, improving sensory abilities, for example, can provide benefits in a variety of ways – for people with Alzheimer's and also for their caregivers from whom unnecessary burden can be lifted," Carrillo said.
Study participants were recruited from dementia and ophthalmology clinics at University Hospitals Case Medical Center and MetroHealth Medical Center in Cleveland, Ohio, and were divided into two groups: (1) immediate surgery following recruitment and (2) delayed or refused surgery. Vision and cognitive status, mood, and capability to complete daily activities were evaluated at baseline and six months after recruitment, or six months after surgery.
Preliminary analysis of results from 20 surgical and eight non-surgical participants showed that the surgical group had significantly improved visual acuity and quality of life, reduced decline in memory and executive functioning, and improvements in behavioral measures compared with the non-surgical group. Levels of perceived burden for caregivers of people in the surgical group also showed improvement.
Cataracts and Cataract Surgery
To date, no medication or eye drop has been proven to prevent or reverse cataract formation. If a cataract is causing nearsightedness or a change in an individual's prescription, new prescription eyeglasses can help improve blurred vision. The only treatment for a cataract, however, is surgical removal of the natural lens.
When to Remove? Sooner or Later?
A cataract should not be removed simply because it is present. Many people have cataracts that do not cause blurred vision, interfere with activities of daily living, or otherwise prevent them from leading active and productive lives. In such cases, these individuals should not undergo unnecessary surgery to remove their cataracts.
However, if an individual has a cataract and resultant blurred vision that makes it difficult to read or continue the daily activities that he or she wants and needs to do, it is time to consider cataract surgery.
If there are cataracts in both eyes that require surgery, the surgeries are usually performed several weeks apart. Cataract surgery on both eyes at the same time is not recommended because there is a possibility of complications affecting both eyes – the most worrisome complication is infection.
How Much Should the Cataract Develop Before Having Surgery?
A cataract does not have to become "ripe" before it can be removed. In the past, the lens could not be extracted safely from the eye unless it was at a relatively advanced stage of development. With modern advances in cataract surgery, however, the lens can now be removed from the eye at any stage of development.
It is true that the longer a cataract develops, the more it hardens. At advanced stages, a firmer or more developed cataract can be difficult to remove. In certain situations, it is safer to remove a cataract sooner rather than later; in most cases, however, an individual should not undergo cataract surgery unless he or she is experiencing blurred vision caused by the cataract.
It is also true that if cataracts are allowed to develop for long periods of time, they can cause inflammation or increased intraocular (within the eye) pressure that can lead to glaucoma.
In these situations, it is extremely important to remove the cataract to prevent loss of vision from the resultant inflammation or glaucoma. This scenario rarely occurs in the United States, however, due to regular access to most types of health care.
More about the Study from AAIC
From the presentation abstract:
Background: Medical co-morbidities [i.e., co-existing medical conditions] often lead to disproportionate adverse effects in dementia. Cataracts are a prominent age related-comorbidity, often co-occurring with Alzheimer's disease (AD) or dementia. The utility of cataract removal in AD in terms of improving visual acuity and Quality of life (QoL) are unknown.
Considerations for surgical removal include the possibility that improved vision may contribute to better cognitive status. Conversely, since AD is a brain disease, improving peripheral sensory input may not materially affect brain function.
Furthermore, the safety risks and potential surgical complications in demented individuals may be sufficiently great to warrant appropriate reticence among treating physicians and ophthalmologists.
To address these questions, we are conducting a clinical trial to determine the effects of cataract removal on visual acuity, spatial contrast sensitivity, vision dependent functions, visual information processing, cognitive measures and QoL in patients with dementia.
Methods: Patients were recruited from dementia and ophthalmology clinics at University Hospitals Case Medical Center and Metro Health Medical Center. Forty-three participants have been enrolled with recruitment ongoing. The current analysis includes 28 protocol completers: 20 in the surgery group, 8 in the non-surgery group.
Conclusions: Our preliminary results show that cataract surgery can improve visual acuity and visual QoL, while reducing decline in memory, and executive function and showing improvements in behavioral measures. Our findings suggest the need to aggressively address dementia co-morbidities such as cataract impairing vision while balancing safety and medical risks.
Preliminary Results and Future Research
According to lead study author Dr. Alan Lerner, "These preliminary results indicate that improved vision can have a variety of benefits for people with dementia and their loved ones, both visual and non-visual. Our findings need to be verified in a larger study, but they suggest the need to aggressively address dementia co-morbidities such as vision-impairing cataracts, while balancing safety and medical risks."
"If the results hold up, it will significantly affect how we treat cataracts in individuals with dementia. Other interventions to offset sensory loss – including vision and hearing – may help improve quality of life for people with dementia and their caregivers," Lerner added.
by Maureen Duffy
Researchers from the United States and China have demonstrated that (a) acute glaucoma in mice presents as an inflammatory disease and (b) elevated eye pressure causes vision loss by setting in motion an inflammatory response similar to that evoked by bacterial infections.
This research is in its earliest stages and has been conducted only with laboratory mice. Nevertheless, the concept shows great promise for persons with acute glaucoma.
The research, entitled Caspase-8 promotes NLRP1/NLRP3 inflammasome activation and IL-1ß production in acute glaucoma (explained below) was published in the July 14, 2014 Early Edition of Proceedings of the National Academy of Sciences. Proceedings, first published in 1915, is the official journal of the United States National Academy of Sciences. It publishes research reports, commentaries, and reviews that span the biological, physical, and social sciences.
The authors are Wei Chi; Fei Li; Hongrui Chen; Yandong Wang; Yingting Zhua; Xuejiao Yang; Jie Zhu; Frances Wu; Hong Ouyang; Jian Ge; Robert N. Weinreb; Kang Zhang; and Yehong Zhuo, who represent the following institutions: Sun Yat-sen University, Guangzhou, China; and the Shiley Eye Center, University of California, San Diego, La Jolla.
About Acute Glaucoma and Inflammation Research
From Acute glaucoma discovered to be an inflammatory disease, via Medical Xpress:
"Our research is the first to show an inflammatory mechanism by which high ocular pressure causes vision loss in acute glaucoma patients," said co-senior author Kang Zhang, MD, PhD and professor of ophthalmology.
Less than 10 percent of glaucoma patients in America have the closed-angle [i.e., acute] form, but in parts of Asia it accounts for almost half of all cases. The higher prevalence of closed-angle glaucoma in Asians and women is believed to be due to a shallower anterior (frontal) eye chamber.
In the study, researchers showed that a rapid, sustained large increase in eye pressure in mice turns on a gene (TLR4) that activates a protein known as caspase-8. This signaling protein in turn triggers the production of inflammatory proteins that normally help mammals fight microbial infections [i.e., a microorganism, especially a bacterium that causes disease].
"This immune response is a double-edged sword because, while these proteins protect us from infection in a normal situation, they stimulate apoptosis (programmed cell death) in retinal cells in cases of acute glaucoma," said Zhang.
To further confirm the mechanism linking high eye pressure to retinal damage, researchers showed that they could slow retinal cell death in mice with acute glaucoma by suppressing either the TLR4 gene or caspace-8 protein.
The latter is particularly significant because caspace-8 inhibitors are currently in clinical trials for treating cancer and stroke. "By injecting these inhibitors into the eyes of acute glaucoma patients, it may be possible to evaluate and bring them vision-sparing treatments more quickly," said co-author Robert N. Weinreb.
What Is Glaucoma?
The term "glaucoma" describes a group of eye diseases that can lead to blindness by damaging the optic nerve. It is one of the leading causes of vision loss and blindness. The human eye continuously produces a fluid, called the aqueous, that must drain from the eye to maintain healthy eye pressure.
Types of Glaucoma
In primary open-angle glaucoma, the most common type of glaucoma, the eye's drainage canals become blocked, and the fluid accumulation causes pressure to build within the eye. This increasing pressure can cause damage to the optic nerve, which transmits information from the eye to the brain. Vision loss is usually gradual and often there are no early warning signs.
In angle-closure glaucoma, also called "acute" glaucoma, the aqueous cannot drain properly because the entrance to the drainage canal is either too narrow or is closed completely. In this case, eye pressure can rise very quickly and cause an acute glaucoma attack. Symptoms can include sudden eye pain, nausea, headaches, and blurred vision. Acute glaucoma is a true ocular emergency and requires immediate treatment.
In normal-tension glaucoma, also called low-tension/low pressure glaucoma, individuals with the disease experience optic nerve damage and subsequent vision loss, despite having normal intraocular [i.e., within the eye] pressure (IOP).
Most eye care professionals define the range of normal IOP as between 10 and 21 mm Hg [i.e., millimeters of mercury, which is a pressure measurement]. Most persons with glaucoma have an IOP measurement of greater than 21 mm Hg; persons with normal-tension glaucoma, however, have an IOP measurement within the normal range.
Visual Field Loss
Glaucoma results in peripheral (or side) vision loss initially, and the effect as this field loss progresses is like looking through a tube or into a narrow tunnel. This constricted "tunnel vision" effect makes it difficult to walk without bumping into objects that are off to the side, near the head, or at foot level.
A living room viewed through a constricted visual field.
Source: Making Life More Livable. Used with permission.
Glaucoma is an especially dangerous eye condition because most people do not experience any symptoms or early warning signs at the onset. Glaucoma can be treated, but it is not curable. The damage to the optic nerve from glaucoma cannot be reversed.
More about the Study from Proceedings of the National Academy of Sciences
From the study summary and abstract:
Acute glaucoma is a sight-threatening condition characterized by a sudden and substantial rise in intraocular pressure (IOP) and consequent retinal ganglion cell death. [Note: Ganglion cells are a type of nerve cell that is found in the retina.]
Angle closure glaucoma, a common cause of glaucoma in Asia that affects tens of millions of people worldwide, often presents acutely with loss of vision, pain, and high IOP.
Even when medical and surgical treatment is available, acute angle closure glaucoma can cause permanent and irreversible loss of vision. TLR4 signaling has been previously implicated in the pathogenesis [i.e., the mechanisms that cause it] of IOP-induced retinal ganglion cell death, although the underlying mechanisms are largely unknown.
In the present study, we used an acute IOP elevation/glaucoma model to investigate the underlying mechanism of retinal ganglion cell death … This study demonstrates the critical role of caspase-8 in IOP-induced cell death in rodent models of acute glaucoma.
These findings identify a mechanism of retinal ganglion cell death and provide a previously unidentified treatment strategy to preserve vision in acute glaucoma.
VisionAware will provide updates of this glaucoma research as they become available.
More Glaucoma and Inflammation Research
by Maureen Duffy
The first clinical trial to examine integrated low vision and mental health treatment – bridging ophthalmology, optometry, psychiatry, psychology, and rehabilitation – has demonstrated that an interdisciplinary rehabilitation program can reduce the incidence of depression by half among older adults with low vision due to age-related macular degeneration (AMD).
Ophthalmology: the Journal
The research, entitled Low Vision Depression Prevention Trial in Age-Related Macular Degeneration, has been published online ahead-of-print on July 9, 2014 in Ophthalmology, the official journal of the American Academy of Ophthalmology.
The authors are Barry W. Rovner, MD; Robin J. Casten, PhD; Mark T. Hegel, PhD; Robert W. Massof, PhD; Benjamin E. Leiby, PhD; Allen C. Ho, MD; and William S. Tasman, MD, who represent the following institutions: Jefferson Medical College, Philadelphia, PA; Dartmouth Medical School, Lebanon, NH; and Johns Hopkins School of Medicine, Baltimore, MD.
About the Research
"Our results emphasize the high risk of depression from AMD, and the benefits of multi-disciplinary treatment that bridges primary eye care, psychiatry, psychology, and rehabilitation," said Barry Rovner, M.D., a professor of psychiatry and neurology at Thomas Jefferson University in Philadelphia.
"The depression is a response to disability, so we reasoned an effective treatment would be to reduce the disability through rehabilitation," Dr. Rovner said. In the Low Vision Depression Prevention Trial (VITAL), he led a team of psychologists, ophthalmologists, optometrists, and occupational therapists to test an approach called behavior activation.
"Behavior activation involves helping people to focus on activities they enjoy, to recognize that loss of those activities can lead to depression, and to re-engage in those activities," said Robin Casten, Ph.D., a co-author and an associate professor of psychiatry and human behavior at Jefferson. Helping people maintain an active social life is an important part of the approach, she said.
The trial recruited 188 participants with bilateral [i.e., in both eyes] AMD from an ophthalmology practice affiliated with Wills Eye Hospital in Philadelphia. The participants were 84 years of age on average, 70 percent were women, and 50 percent lived alone. All had a best-corrected visual acuity of less than 20/70.
Each participant had mild depressive symptoms and was at risk for developing clinical depression, based on a nine-item depression subtest of the Patient Health Questionnaire.
During the trial, each participant had two visits with an optometrist, during which they were prescribed low vision devices, such as hand-held magnifiers. After those initial visits, the participants were randomly divided into two groups for two different interventions (described below).
[After four months], 18 (23.4 percent) in the control group and 11 (12.6 percent) in the behavior activation group developed clinical depression. Behavior activation had the most benefit for participants with the worst vision (less than 20/100), reducing the risk of depression by about 60 percent compared to [the control group].
When the data were adjusted for vision status, physical health, and baseline [depression] score, behavior activation reduced the risk of depression by 50 percent compared to the control treatment.
As described in the Low Vision Depression Prevention Trial for Age Related Macular Degeneration, the two interventions were as follows:
Behavior Activation + Low Vision Rehabilitation (The Active Treatment)
- Also called Collaborative Low Vision Rehabilitation (optometrist and home-based occupational therapist)
- Used low vision clinic-based optometry, plus six in-home occupational therapy visits
- A low vision occupational therapist (OT) delivered Behavior Activation, a psychological treatment to prevent depression.
- The optometrists evaluated vision and magnification needs, prescribed low vision optical devices, and provided the OTs with initial care plans.
- The OTs met with participants in their homes six times over 12 weeks to enhance low vision device use, home modifications, and compensatory strategies, such as increasing social activities, setting personal goals, and breaking goals down into manageable steps.
Supportive Therapy + Low Vision Rehabilitation (The Placebo or Comparison)
- Also called Enhanced Low Vision Rehabilitation (optometrist and home-based Supportive Therapy)
- Used low vision clinic-based optometry, plus six in-home Supportive Therapy sessions over 12 weeks
- Supportive therapy is a placebo treatment that controls for the attention the participants in the active treatment group received.
- [Editor's note: In research terminology, a placebo is an intervention or a drug that has no therapeutic effect or contains no active medication.]
About Low Vision
Low vision is uncorrectable vision loss that interferes with daily living activities. It is better defined in terms of function, rather than [numerical] test results. In other words, low vision is "not enough vision to do whatever it is you need to do," which can vary from person to person.
Most eye care professionals use the term "low vision" to describe permanently reduced vision that cannot be corrected with regular glasses, contact lenses, medicine, or surgery. One of the primary causes of low vision is AMD.
You can learn more about low vision at Low Vision and Legal Blindness Terms and Descriptions and What is a Low Vision Examination? on the VisionAware website.
What are Low Vision Rehabilitation Services?
Vision rehabilitation services enable adults who are blind or have low vision to continue living independently. The terms "vision rehabilitation" and "low vision rehabilitation" include highly trained professionals and comprehensive services that can restore function after vision loss, just as physical therapy restores function after a stroke or other injury.
In addition to the interventions described in the VITAL Trial, the full range of vision rehabilitation services and professionals includes the following:
- Low Vision Therapists: teach the use of residual vision with optical devices, non-optical devices, and assistive technology, and help determine the need for environmental modifications in the home or workplace.
- Vision Rehabilitation Therapists: teach adaptive independent living skills that enable adults to perform a wide range of daily activities, including meal preparation, reading and writing, home repair, personal self-care, and financial management.
- Orientation and Mobility Specialists: teach safe and independent indoor and outdoor travel skills, including the use of a long cane, electronic travel devices, public transportation, human guide techniques, and pre-cane skills.
Additional vision rehabilitation services can include:
- Peer support and counseling: talking with peers, sharing common concerns and frustrations, and finding solutions to vision-related problems
- Vocational rehabilitation: vocational evaluation and training, job training, job modification and restructuring, and job placement
- Veterans' services: vision rehabilitation and related support services for blinded veterans of all ages.
More about the Low Vision Depression Prevention Trial Study Results
From the article abstract:
Purpose: To compare the efficacy of behavior activation + low vision rehabilitation with supportive therapy + low vision rehabilitation to prevent depressive disorders in patients with age-related macular degeneration.
Interventions: Before randomization, all subjects had two outpatient low vision rehabilitation visits, and were then randomized to in-home behavior activation + low vision rehabilitation or supportive therapy + low vision rehabilitation.
Behavior activation is a structured behavioral treatment that aims to increase adaptive behaviors and achieve valued goals. Supportive therapy is a nondirective, psychological treatment that provides emotional support and controls for attention.
Results: At four months, 11 behavior activation + low vision rehabilitation subjects (12.6%) and 18 supportive therapy + low vision rehabilitation subjects (23.4%) developed a depressive disorder.
A mediational analysis suggested that behavioral activation + low vision rehabilitation prevented depression to the extent that it enabled subjects to remain socially engaged.
In addition, behavioral activation + low vision rehabilitation was associated with greater improvements in functional vision than supportive therapy + low vision rehabilitation, although there was no significant between-group difference. There was no significant change or between-group difference in quality of life.
Conclusions: An integrated mental health and low vision intervention halved the incidence of depressive disorders relative to standard outpatient low vision rehabilitation in patients with AMD.
As the population ages, the number of persons with AMD and the adverse effects of comorbid [i.e., coexisting] depression will increase. Promoting interactions between ophthalmology, optometry, rehabilitation, psychiatry, and behavioral psychology may prevent depression in this population.
As summarized by Dr. Barry Rovner in Science Codex, "Our findings demonstrate that referring patients with AMD-related low vision for low vision optometric rehabilitation alone does not fully meet the patients' rehabilitative needs. Although low vision occupational therapists do not currently receive training in mental health care, our results indicate that interdisciplinary care like this could significantly help reduce the incidence of depression in patients with AMD."
Please note: The study is continuing to follow participants to determine if the benefits of treatment are maintained after one year.
How to Locate Low Vision Rehabilitation Services
The VisionAware Directory of Services allows you to browse by state and type of service, including counseling resources, support groups, low vision services, independent living skills, and orientation and mobility. The VisionAware "Getting Started" kit provides tip sheets on specialized services and products that can assist with everyday life after vision loss.
by Maureen Duffy
A group of Australian researchers has demonstrated that treating wet age-related macular degeneration with Lucentis, Eylea, or Avastin injections not only increases patients' visual acuity – it can also improve their vision-related quality of life.
Ophthalmology: the Journal
The research, entitled The Impact of Anti–Vascular Endothelial Growth [i.e., anti-VEGF, explained below] Factor Treatment on Quality of Life in Neovascular Age-Related Macular Degeneration, have been published in the June, 2014 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 Robert P. Finger, PhD; Robyn H. Guymer, PhD; Mark C. Gillies, PhD; and Jill E. Keeffe, PhD, who represent the following Australian institutions: the Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne; and the Save Sight Institute, University of Sydney.
About Wet, or Neovascular, Age-Related Macular Degeneration (AMD)
In wet, or exudative, macular degeneration (AMD), the choroid (a part of the eye containing blood vessels that nourish the retina) begins to sprout abnormal new blood vessels that develop into a cluster under the macula. This process is called choroidal neovascularization or CNV (neo = new; vascular = blood vessels).
The macula is the part of the retina that provides the clearest central vision. Because these new blood vessels are abnormal, they tend to break, bleed, and leak fluid under the macula, causing it to lift up and pull away from its base. This damages the fragile photoreceptor cells, which sense and receive light, resulting in a rapid and severe loss of central vision.
Anti-Angiogenic Drugs and Anti-VEGF Treatments
Angiogenesis is a term used to describe the growth of new blood vessels and plays a crucial role in the normal development of body organs and tissue. Sometimes, however, excessive and abnormal blood vessel development can occur in diseases such as cancer (tumor growth) and AMD (retinal and macular bleeding).
Substances that stop the growth of these excessive blood vessels are called anti-angiogenic (anti=against; angio=vessel; genic=development), and anti-neovascular (anti=against; neo=new; vascular=blood vessels).
The focus of current anti-angiogenic drug treatments for wet AMD is to reduce the level of a particular protein (vascular endothelial growth factor, or VEGF) that stimulates abnormal blood vessel growth in the retina and macula; thus, these drugs are classified as anti-VEGF treatments and include Lucentis, Eylea, and Avastin. They are administered by injection directly into the eye after the surface has been numbed.
More about the Research
From Anti-VEGF Improves Quality of Life in Macular Degeneration, via Medscape (registration required):
[A Phase 3 clinical trial of Lucentis] had reported an increase in vision-related quality of life with treatment, but later studies found mixed results. Dr. Finger and colleagues suspected that a better questionnaire could assess quality of life more accurately, so instead of the 25-item National Eye Institute Visual Functioning Questionnaire, they used the Impact of Vision Impairment (IVI) [questionnaire].
[Editor's notes: In Phase 3 of a clinical trial, the study drug or treatment is given to larger groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
The Impact of Vision Impairment (IVI) scale is a short questionnaire that was developed to measure the impact of vision impairment on participation in activities of daily living. Each questionnaire item is rated on a six-level scale from "no difficulty" to "can't do because of vision." The IVI questionnaire measures vision-related quality of life in three main areas: (a) reading and accessing information, (b) mobility and independence, and (c) emotional well-being.]
The researchers recruited participants from outpatient clinics at the Royal Victorian Eye and Ear Hospital in Melbourne, Australia. The participants all had newly diagnosed neovascular [i.e., wet] age-related macular degeneration and had not yet undergone treatment.
They received three monthly injections of 0.5 mg [Lucentis], followed by either continued monthly injections or a treat-and-extend protocol. Of the 169 participants, 56% were women; mean age was 79 years. At the 12-month mark, 120 patients were still enrolled.
More about the Study Results and Quality of Life
From the article abstract:
Purpose: To assess the impact of anti–vascular endothelial growth factor (VEGF) treatment in routine medical practice on vision-related quality of life in neovascular age-related macular degeneration.
Methods: The vision-related quality of life interviews administered at [the beginning, six months, and 12 months]; routine anti-VEGF treatment with up to monthly follow-ups; and re-treatment as indicated. The Impact of Vision Impairment (IVI) questionnaire was subjected to [rigorous] analysis to assess its measurement performance.
Findings: The mean age was 70 years; 56% were female. Visual acuity improved by a mean of eight letters [as measured on a LogMAR eye chart].
Those who lost more than two lines [on the eye chart] (13 persons, or 11%) reported worse vision-related quality of life in the Accessing Information and Mobility areas.
Those who gained more than two lines [on the eye chart] (29 persons, or 24%) reported better vision-related quality of life in the Accessing Information and Emotional Well-being areas.
Patients who did not experience a change in visual acuity reported no change in their vision-related quality of life.
Only a change in visual acuity, but not whether the better or worse eye was treated, predicted a change in vision-related quality of life in the Accessing Information and Emotional Well-being areas.
Conclusions: We confirmed that anti-VEGF treatment for neovascular macular degeneration improves patients' vision-related quality of life in those who gain vision and maintains vision-related quality of life in those who maintain visual acuity in their treated eye, irrespective of whether the worse or better eye is treated. Against this background, the best possible outcomes should be aimed for, even if the worse eye is treated because a loss of visual acuity in the worse-seeing eye will adversely affect patients' vision-related quality of life.
As summarized by Medscape, the results remained consistent, regardless of whether the better or worse eye was treated. The investigators wrote that "even worse eyes should receive treatment" and that any treatment should aim to improve, or at least maintain, visual acuity, since any loss of visual acuity seems to translate directly to a reduced quality of life.
- Risk Factors for Age-Related Macular Degeneration
- New Research: Are Lucentis, Avastin, and Eylea Risk Factors for Increased Eye Pressure?
- Is It Possible to Predict Risk for Developing Macular Degeneration? A New Study Says Yes
- Why Do Some People Not Respond to Eye Injections for Macular Degeneration?
by Maureen Duffy
Researchers from the United States and Europe are attempting to improve the quality of artificial vision, such as the images produced by the Argus II Retinal Prosthesis, also called the "bionic eye."
Their preliminary laboratory research indicates that electrical stimulation of retinal cells can produce the same patterns of activity (or "natural vision") that occur when the retina views a moving object, including the ability to see shape, color, and depth.
From the Journal Neuron
The research, entitled High-Fidelity Reproduction of Spatiotemporal Visual Signals for Retinal Prosthesis, was published in the July 2, 2014 edition of Neuron. Neuron serves as a forum for the neuroscience community, publishing research on sensory, motor, and higher-order cognitive functioning.
[Note: The term "spatiotemporal" relates to both time and space. "Spatial" refers to the relationship of objects within an area or space, while "temporal" refers to a sequence of events occurring in real time.]
The authors are Lauren H. Jepson; Pawel Hottowy; Geoffrey A. Weiner; Wladyslaw Dabrowski; Alan M. Litke; and E.J. Chichilnisky, who represent the following institutions: Salk Institute for Biological Studies, La Jolla, CA; University of California, San Diego; AGH University of Science and Technology, Krakow, Poland; University of California, La Jolla; University of California, Santa Cruz; and Stanford University, Stanford, CA.
About the Research
In laboratory tests, researchers have used electrical stimulation of retinal cells to produce the same patterns of activity that occur when the retina sees a moving object. Although more work remains, this is a step toward restoring natural, high-fidelity vision to blind people, the researchers say.
Just 20 years ago, "bionic" vision was more a science fiction cliché than a realistic medical goal. But in the past few years, the first artificial vision technology has come on the market in the United States and Western Europe, allowing people who've been blinded by retinitis pigmentosa to regain some of their sight. While remarkable, the technology has its limits. It has enabled people to navigate through a door and even read headline-sized letters, but not to drive, jog down the street, or see a loved one's face.
The Retina and Artificial Vision
The retina contains several cell layers. The first layer contains photoreceptor cells, which detect light and convert it into electrical signals. Retinitis pigmentosa and several other blinding diseases are caused by a loss of these cells. The strategy behind many bionic retinas, or retinal prosthetics, is to bypass the need for photoreceptors and stimulate the retinal ganglion cell layer, the last stop in the retina before visual signals are sent to the brain.
Current technology does not have enough specificity or precision to reproduce natural vision, he said. Although much of visual processing occurs within the brain, some processing is accomplished by retinal ganglion cells. There are 1 to 1.5 million retinal ganglion cells inside the retina, in at least 20 varieties. Natural vision – including the ability to see details in shape, color, depth, and motion – requires activating the right cells at the right time.
Parasol Cells and Artificial Vision
The new study shows that patterned electrical stimulation can do just that in isolated retinal tissue. The [researchers] focused their efforts on a type of retinal ganglion cell called parasol cells. These cells are known to be important for detecting movement, and its direction and speed, within a visual scene. When a moving object passes through visual space, the cells are activated in waves across the retina.
The researchers placed patches of retina on a 61-electrode grid. Then they sent out pulses at each of the electrodes and listened for cells to respond, almost like sonar. This enabled them to identify parasol cells, which have distinct responses from other retinal ganglion cells. It also established the amount of stimulation required to activate each of the cells.
Next, the researchers recorded the cells' responses to a simple moving image – a white bar passing over a gray background.
Finally, they electrically stimulated the cells in this same pattern, at the required strengths. They were able to reproduce the same waves of parasol cell activity that they observed with the moving image.
One Type of Artificial Vision: the Argus II Retinal Prosthesis
The Argus II has been approved to treat adults with severe to profound retinitis pigmentosa (RP), 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 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 $150,000; 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.
More about the Study from Neuron
From the article overview:
Natural vision relies on spatiotemporal patterns of electrical activity in the retina. We investigated the feasibility of … reproducing such patterns with epiretinal [i.e., overlying the retina] prostheses.
Multielectrode recordings and visual and electrical stimulation were performed on populations of identified ganglion cells in isolated peripheral primate retina. Electrical stimulation patterns were designed to reproduce recorded waves of activity elicited by a moving visual stimulus.
Electrical responses in … parasol cells exhibited high spatial and temporal precision, matching or exceeding the precision of visual responses measured in the same cells.
These results suggest the possibility of producing rich spatiotemporal patterns of retinal activity with a prosthesis and that temporal multiplexing [i.e., combining multiple message signals or data streams into one signal] may aid in reproducing the neural code of the retina.
- The Argus II Retinal Prosthesis ("Bionic Eye") Receives Medicare Approval
- The Argus II: Fact or Science Fiction? A "Bionic Eye" Pioneer Tells Her Story
- Meet Duane Geruschat, Ph.D. and the Argus II Retinal Prosthesis at Second Sight Medical Products
VisionAware will continue to report on artificial vision research projects as they become available.
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