Tag: Ophthalmology

Japanese study of induced pluripotent stem cells aims to demonstrate safety in humans. Induced pluripotent stem cells could soon be used in human trials in Japan. In the seven years since their discovery, induced pluripotent stem (iPS) cells have transformed basic research and won a Nobel prize. Now, a Japanese study is about to test the medical potential of these cells for the first time. Made by reprogramming adult cells into an embryo-like state that can form any cell type in the body, the cells will be transplanted into patients who have a debilitating eye disease. Masayo Takahashi, an ophthalmologist at the RIKEN Center for Developmental Biology in Kobe, Japan, plans to submit her application for the study to the Japanese health ministry next month, and could be recruiting patients as early as September. Stem-cell researchers around the world hope that if the trial goes forward, it will allay some of the safety concerns over medical use of the cells. And the Japanese government hopes that its efforts to speed iPS cells to the clinic by generously funding such work will be vindicated. “The entire field is very dependent on this group and the Japanese regulatory agencies to ensure that preclinical evidence for safety and efficacy is very strong,” says Martin Pera, a stem-cell expert at the University of Melbourne in Australia.

Takahashi, who has been studying the potential of iPS cells to rebuild diseased tissue for more than a decade, hopes to treat around six people who have severe age-related macular degeneration, a common cause of blindness that affects at least 1% of people aged over 50. The form of the disease that Takahashi will treat occurs when blood vessels invade the retina, destroying the retinal pigment epithelium that supports the light-sensitive photoreceptors. This form can be treated with drugs that block the growth of new blood vessels, but these often have to be injected repeatedly into the eye. Takahashi will take a peppercorn-size skin sample from the upper arm and add proteins that reprogram the cells into iPS cells. Other factors will transform the iPS cells into retinal cells. Then a small sheet of cells will be placed under the damaged area of the retina, where, if things go well, the cells will grow and repair the pigment epithelium. The researchers hope to see the transplants slow or halt the disease, but their main goal is to show that the cells are safe. One concern is that the reprogrammed cells will trigger an immune reaction — as has been seen in mice (T. Zhao et al. Nature 474, 212–215; 2011). But that concern has faded after a recent study suggested that iPS cells did not provoke an immune reaction after all. “Immune compatibility seems to be as expected, so I am not so concerned about that issue,” says stem-cell expert George Daley of Harvard Medical School in Boston, Massachusetts.

A bigger worry is that the reprogrammed cells might multiply uncontrollably and form tumours instead of healthy tissue. But Pera and Daley are reassured by the pre-clinical data that Takahashi has presented at conferences. Takahashi says that these results, submitted for publication, show that her iPS cells do not form tumours in mice and are safe in non-human primates. Pera adds that the procedure to treat macular degeneration requires just a few stem cells, reducing the chances that a tumour will form. Also, any tumours would be relatively easy to remove because the eye is more accessible than some organs. Daley does worry that the treatment, even if it proves harmless, might not be effective. The cells might not engraft properly, for example, or might not integrate with the patients’ own tissue. “I think we will require many years of experience to learn more about how cells integrate,” he says. Pera raises another concern: that the identity of the cells might not be stable, and that over time they would no longer function as retinal epithelium. “The entire field is very dependent on this group and the Japanese regulatory agencies.”

According to Robert Lanza, chief scientific officer at biotechnology firm Advanced Cell Technology (ACT) in Santa Monica, California, iPS-cell studies like Takahashi’s could be premature. “I cannot imagine any regulatory agency permitting such a trial without years of extensive pre-clinical testing,” he says. ACT is racing to start a less-ambitious clinical trial of iPS cells for use in other diseases. Its study would inject healthy patients with platelets derived from iPS cells and from embryonic stem cells to see if they act like normal platelets, which could open the way to a treatment for blood-clotting disorders. Because platelets lack a nucleus, there is no risk of forming tumours, explains Lanza. He will meet with the US Food and Drug Administration later this month, and hopes to get approval to start the trial this year. Lanza says that using iPS cells that contain a nucleus in human trials is “a far greater challenge” than his approach. But Takahashi’s team is prepared, counters Pera. They are “among the pioneers in this field”, he says, adding that they are “well placed to undertake these studies”.

Takahashi is carrying out a ‘clinical study’ which, in Japan’s somewhat confusing system, is less tightly regulated than a clinical trial and cannot by itself lead to approval for clinical use of a treatment. The data, if positive, might attract investors or help Takahashi to get approval for a formal clinical trial — required if the cells are ever to be used to treat patients in the clinic. The study was approved by institutional review boards at both the Center for Developmental Biology and the Institute of Biomedical Research and Innovation in Kobe, where the surgical procedures will be carried out. Now, approval depends on a health-ministry committee of 18 physicians, lawyers, administrators and scientists, including three stem-cell specialists. If Takahashi wins approval by September as expected, it will take another eight months to grow the sheets of cells required for the transplants. In Japan, future iPS-cell therapies may have an easier path to the clinic as the government continues its drive to capitalize on the technology, which was first developed there. A revised drug law, expected to be put before the Japanese parliament by late June, would fast-track therapies that seem to be effective in phase II or phase III trials. But the success of that drive, and the prospects for patients with macular degeneration, depend in part on Takahashi and her pioneering patients.

Nature
March 19, 2013

Original web page at Nature

FDA’s green light for Second Sight’s Argus II Retinal Prosthesis System gives hope to those blinded by a rare genetic eye condition called advanced retinitis pigmentosa, which damages the light-sensitive cells that line the retina. For Second Sight, FDA approval follows more than 20 years of development, two clinical trials and more than $200 million in funding—half from the National Eye Institute, the Department of Energy and the National Science Foundation, and the rest from private investors. The Argus II has been approved for use in Europe since 2011 and implanted in 30 clinical-trial patients since 2007. The FDA’s Ophthalmic Devices Advisory Panel in September 2012 voted unanimously to recommend approval. The Argus II includes a small video camera, a transmitter mounted on a pair of eyeglasses, a video processing unit and a 60-electrode implanted retinal prosthesis that replaces the function of degenerated cells in the retina, the membrane lining the inside of the eye. Although it does not fully restore vision, this setup can improve a patient’s ability to perceive images and movement, using the video processing unit to transform images from the video camera into electronic data that is wirelessly transmitted to the retinal prosthesis.

Retinitis pigmentosa—which affects about one in 4,000 people in the US and about 1.5 million people worldwide—kills the retina’s photoreceptors, the rod and cone cells that convert light into electrical signals transmitted via the optic nerve to the brain’s visual cortex for processing. Second Sight plans to adapt its technology to someday assist people afflicted with age-related macular degeneration, a similar but more common disease. The company plans to make the Argus II available later this year in clinical centers throughout the US, cultivate a network of surgeons who can implant the device and recruit hospitals to offer it.

The Argus II is not the only retinal implant under development. Retina Implant AG takes a slightly different approach by making a prosthetic inserted beneath a portion of the retina. The company’s technology is a three- by three-millimeter microelectronic chip (0.1-millimeter thick) containing about 1,500 light-sensitive photodiodes, amplifiers and electrodes surgically inserted beneath the fovea (which contains the cone cells) in the retina’s macula region. The fovea enables the clarity of vision that people rely on to read, watch TV and drive. The chip helps generate at least partial vision by stimulating intact nerve cells in the retina. The nerve impulses from these cells are then led via the optic nerve to the visual cortex where they create impressions of sight. The chip’s power source is positioned under the skin behind the ear and connected via a thin cable—no glasses or camera required. In May the company announced the first UK patients participating its latest trial had successfully received implants. To date surgeons have implanted Retina Implant prosthetics in 36 patients through two clinical trials over six years.

Stanford University researchers are in the early stages of developing self-powered retinal implants where each pixel in the device is fitted with silicon photodiodes. These sensors detect light, and control the output of a pulsed electrical current. Patients would wear goggles that emit near-infrared pulses that transmit both power and data directly to the photodiodes. Other retinal prosthesis are powered by inductive coils that, along with other components, must be surgically implanted in the patient’s head. The researchers reported on the plausibility of their design in the May 2012 issue of Nature Photonics, describing in vitro electrical stimulation of healthy and degenerate rat retina by photodiodes powered by near-infrared light. Weill Cornell Medical College researchers in New York City are taking retinal prosthetics in a different direction, having deciphered the neural codes that mouse and monkey retinas use to turn light patterns into patterns of electrical pulses that their brains translate into meaningful images. The researchers programmed this information into an “encoder” chip and combined it with a mini-projector to create an implantable prosthetic. The chip converts images that come into the eye into streams of electrical impulses, and the mini-projector then converts the electrical impulses into light impulses that are sent to the brain. Rather than increasing the number of electrodes placed in an eye to capture more information and send signals to the brain, this work focuses on the quality of the artificial signals themselves so as to improve their ability to carry impulses to the brain.

Nature
March 5, 2013

Original web page at Nature

Human corneal endothelial cells (HCEnCs) form a monolayer of hexagonal cells whose main function is to maintain corneal clarity by regulating corneal hydration. Cell loss due to aging or corneal endothelial disorders, such as Fuchs dystrophy, can lead to cornea edema and blindness, resulting in the need for cornea transplants. Studying human corneal endothelium has been difficult for cell biologists because limited cellular model systems exist and have significant drawbacks. The major drawback is that HCEnC cells do not divide and there is a limited source of these cells both for patient transplantation and for study in the laboratory. This field of study is now easier. Scientists from the Schepens Eye Research Institute, Mass. Eye and Ear, have developed of HCENC-21 and HCEnC-21T, two novel model systems for human corneal endothelium. Their findings, “Telomerase Immortalization of Human Corneal Endothelial Cells Yield Functional Hexagonal Monolayers,” are online in the PLOS ONE.

A research team led by Ula Jurkunas, M.D., developed first-of their kind model systems for human corneal endothelium. “These models mimic very well the critical characteristics and functionalities known from the tissue in the eye,” Dr. Jurkunas said. “They also fulfill essential technical requirements, e.g. indefinite number of and a high rate of cell division, to be a powerful tool. They will enable cell biologists to more reliably study human corneal endothelium in health and disease. The ability to enhance HCEnC cell self renewal and growth opens a new window of development of novel regenerative therapies for corneal swelling, hopefully reducing the need for corneal transplantation in the future.”

Science Daily
January 22, 2013

Original web page at Science Daily

A new study finds that certain changes in blood vessels in the eye’s retina can be an early warning that a person is at increased risk for glaucoma, an eye disease that slowly robs people of their peripheral vision. Using diagnostic photos and other data from the Australian Blue Mountains Eye Study, the researchers showed that patients who had abnormally narrow retinal arteries when the study began were also those who were most likely to have glaucoma at its 10-year end point. If confirmed by future research, this finding could give ophthalmologists a new way to identify and treat those who are most vulnerable to vision loss from glaucoma. The study was recently published online by Ophthalmology, the journal of the American Academy of Ophthalmology. Open-angle glaucoma (OAG), the most common form of the disease, affects nearly three million people in the U.S and 60 million worldwide. Vision loss occurs when glaucoma damages the optic nerve, the part of the eye that transmits images from the retina to the brain. Unfortunately, because glaucoma does not have symptoms, many people don’t know they have the disease until a good portion of their sight has been lost. Early detection is critical to treating glaucoma in time to preserve vision.

The findings of the new study, led by Paul Mitchell, M.D., PhD, of the Centre for Vision Research, University of Sydney, supports the concept that abnormal narrowing of retinal blood vessels is an important factor in the earliest stages of OAG. Tracking nearly 2,500 participants, the study found that the OAG risk at the 10-year mark was about four times higher in patients whose retinal arteries had been narrowest when the study began, compared with those who had had the widest arteries. None of the participants had a diagnosis of OAG at the study’s outset. Compared with the study group as a whole, the patients who were diagnosed with OAG by the 10-year mark were older, had had higher blood pressure or higher intraocular pressure at the study’s baseline, and were more likely to be female. Elevated intraocular pressure, or pressure within the eye, is often found in patients with OAG. Study results were adjusted for age, family history of glaucoma, smoking, diabetes, hypertension, and other relevant factors. “Our results suggest that a computer-based imaging tool designed to detect narrowing of the retinal artery caliber, or diameter, could effectively identify those who are most at risk for open-angle glaucoma,” said Dr. Mitchell. “Such a tool would also need to account for blood pressure and other factors that can contribute to blood vessel changes. Early detection would allow ophthalmologists to treat patients before optic nerve damage occurs and would give us the best chance of protecting their vision.” A symptomless eye disease like glaucoma highlights the importance of regular eye exams. The American Academy of Ophthalmology recommends that everyone have a complete eye exam by an ophthalmologist at age 40 and stick to the follow-up exam schedule advised by their doctor.

Science Daily
January 22, 2013

Original web page at Science Daily

Since the age of dinosaurs, most species of day-active mammals have retained the imprint of nocturnal life in their eye structures. Humans and other anthropoid primates, such as monkeys and apes, are the only groups that deviate from this pattern, according to a new study from The University of Texas at Austin and Midwestern University. The findings, published in a forthcoming issue of Proceedings of the Royal Society B, are the first to provide a large-scale body of evidence for the “nocturnal bottleneck theory,” which suggests that mammalian sensory traits have been profoundly influenced by an extended period of adaptation to nocturnality during the Mesozoic Era. This period lasted from 250 million years ago to 65 million years ago. To survive in the night, mammals had a host of visual capabilities, such as good color vision and high acuity, which were lost as they passed through the nocturnal “bottleneck.” “The fact that nearly all living mammals have eye shapes that appear ‘nocturnal’ by comparison with other amniotes [mammals, reptiles and birds] is a testament to the strong influence that evolutionary history can have on modern anatomy,” says Chris Kirk, associate professor of anthropology at The University of Texas at Austin. According to Kirk, early mammals were predominantly nocturnal during the Mesozoic partly as a strategy for avoiding predation by day-active dinosaurs.

“It’s a bit surprising to still see the effects of this long period of nocturnality on living mammals more than 65 million years after non-avian dinosaurs went extinct, but that’s exactly what we found,” Kirk says. The research team, led by Margaret Hall, an evolutionary biologist at Midwestern University’s Arizona College of Osteopathic Medicine, analyzed one of the largest datasets on eye morphology ever assembled. Using a sample of eyeballs from 266 mammal species, the researchers used a multivariate statistical method to show that mammals active by day or night show only minor differences in eye morphology. The researchers then compared the eyes of mammals, birds and lizards using the ratio of cornea size and eye length — two functionally important measures of the eye’s ability to admit light and form sharp images. These analyses showed that diurnal (only active by day) and cathemeral (active by both day and night) mammals don’t differ in their eye shapes. At the same time, both groups have eye shapes that are very similar to those of nocturnal birds and lizards. These results reveal that most day-active mammals have eye shapes that appear “nocturnal” when compared with other vertebrates.

One likely reason for these findings, Kirk says, is that after the extinction of non-avian dinosaurs, some nocturnal mammals became day-active and there was less pressure to evolve eye shapes for acute diurnal vision like those of other day-active vertebrates. Anthropoid primates are the only mammalian group that re-evolved eye shape for fine detailed daytime vision. Like diurnal birds and lizards, most anthropoids have small corneas relative to eye length as an adaptation for enhanced visual acuity. Kirk says the study provides a deeper understanding of human sensory systems and our intrinsic connection with our closest living primate relatives: the monkeys and apes. “Humans and other anthropoid primates are so dependent on vision for everything that they do,” Kirk says. “In this case, we are radically different from other mammals. We found that the distinctive eye shapes that set humans apart from most other mammals evolved a long time ago — way back with the origin of anthropoid primates.”

Science Daily
November 13, 2012

Original web page at Science Daily

A new paradigm to explain glaucoma is rapidly emerging, and it is generating brain-based treatment advances that may ultimately vanquish the disease known as the “sneak thief of sight.” A review now available in Ophthalmology, the journal of the American Academy of Ophthalmology, reports that some top researchers no longer think of glaucoma solely as an eye disease. Instead, they view it as a neurologic disorder that causes nerve cells in the brain to degenerate and die, similar to what occurs in Parkinson disease and in Alzheimer’s. The review, led by Jeffrey L Goldberg, M.D., Ph.D., assistant professor of ophthalmology at the Bascom Palmer Eye Institute and Interdisciplinary Stem Cell Institute, describes treatment advances that are either being tested in patients or are scheduled to begin clinical trials soon. Glaucoma is the most common cause of irreversible blindness worldwide. For many years, the prevailing theory was that vision damage in glaucoma patients was caused by abnormally high pressure inside the eye, known as intraocular pressure (IOP). As a result, lowering IOP was the only goal of those who developed surgical techniques and medications to treat glaucoma. Creating tests and instruments to measure and track IOP was crucial to that effort. Today, a patient’s IOP is no longer the only measurement an ophthalmologist uses to diagnose glaucoma, although it is still a key part of deciding how to care for the patient. IOP-lowering medications and surgical techniques continue to be effective ways to protect glaucoma patients’ eyes and vision. Tracking changes in IOP over time informs the doctor whether the treatment plan is working.

But even when surgery or medication successfully lowers IOP, vision loss continues in some glaucoma patients. Also, some patients find it difficult to use eye drop medications as prescribed by their physicians. These significant shortcomings spurred researchers to look beyond IOP as a cause of glaucoma and focus of treatment. The new research paradigm focuses on the damage that occurs in a type of nerve cell called retinal ganglion cells (RGCs), which are vital to the ability to see. These cells connect the eye to the brain through the optic nerve. RGC-targeted glaucoma treatments now in clinical trials include: medications injected into the eye that deliver survival and growth factors to RGCs; medications known to be useful for stroke and Alzheimer’s, such as cytidine-5-diphosphocholine; and electrical stimulation of RGCs, delivered via tiny electrodes implanted in contact lenses or other external devices. Human trials of stem cell therapies are in the planning stages. “As researchers turn their attention to the mechanisms that cause retinal ganglion cells to degenerate and die, they are discovering ways to protect, enhance and even regenerate these vital cells,” said Dr. Goldberg. “Understanding how to prevent damage and improve healthy function in these neurons may ultimately lead to sight-saving treatments for glaucoma and other degenerative eye diseases.” If this neurologically-based research succeeds, future glaucoma treatments may not only prevent glaucoma from stealing patients’ eyesight, but may actually restore vision. Scientists also hope that their in-depth exploration of RGCs will help them determine what factors, such as genetics, make some people more vulnerable to glaucoma.

Science Daily
April 3, 2012

Original web page at Science Daily

For the first time, scientists at the University of Wisconsin-Madison have made early retina structures containing proliferating neuroretinal progenitor cells using induced pluripotent stem (iPS) cells derived from human blood. And in another advance, the retina structures showed the capacity to form layers of cells – as the retina does in normal human development – and these cells possessed the machinery that could allow them to communicate information. (Light-sensitive photoreceptor cells in the retina along the back wall of the eye produce impulses that are ultimately transmitted through the optic nerve and then to the brain, allowing you to see.) Put together, these findings suggest that it is possible to assemble human retinal cells into more complex retinal tissues, all starting from a routine patient blood sample. Many applications of laboratory-built human retinal tissues can be envisioned, including using them to test drugs and study degenerative diseases of the retina such as retinitis pigmentosa, a prominent cause of blindness in children and young adults. One day, it may also be possible replace multiple layers of the retina in order to help patients with more widespread retinal damage.

“We don’t know how far this technology will take us, but the fact that we are able to grow a rudimentary retina structure from a patient’s blood cells is encouraging, not only because it confirms our earlier work using human skin cells, but also because blood as a starting source is convenient to obtain,” says Dr. David Gamm, pediatric ophthalmologist and senior author of the study. “This is a solid step forward.” In 2011, the Gamm lab at the UW Waisman Center created structures from the most primitive stage of retinal development using embryonic stem cells and stem cells derived from human skin. While those structures generated the major types of retinal cells, including photoreceptors, they lacked the organization found in more mature retina. This time, the team, led by Gamm, Assistant Professor of Ophthalmology and Visual Sciences in the UW School of Medicine and Public Health, and postdoctoral researcher and lead author Dr. Joseph Phillips, used their method to grow retina-like tissue from iPS cells derived from human blood gathered via standard blood draw techniques.

In their study, about 16 percent of the initial retinal structures developed distinct layers. The outermost layer primarily contained photoreceptors, whereas the middle and inner layers harbored intermediary retinal neurons and ganglion cells, respectively. This particular arrangement of cells is reminiscent of what is found in the back of the eye. Further, work by Dr. Phillips showed that these retinal cells were capable of making synapses, a prerequisite for them to communicate with one another. The iPS cells used in the study were generated through collaboration with Cellular Dynamics International (CDI) of Madison, Wis., who pioneered the technique to convert blood cells into iPS cells. CDI scientists extracted a type of blood cell called a T-lymphocyte from the donor sample, and reprogrammed the cells into iPS cells. CDI was founded by UW stem cell pioneer Dr. James Thomson. “We were fortunate that CDI shared an interest in our work. Combining our lab’s expertise with that of CDI was critical to the success of this study,” added Dr. Gamm.

Science Daily
April 3, 2012

Original web page Science Daily

A new cornea may be the only way to prevent a patient going blind — but there is a shortage of donated corneas and the queue for transplantation is long. Scientists at the Sahlgrenska Academy have for the first time successfully cultivated stem cells on human corneas, which may in the long term remove the need for donators. Approximately 500 corneal transplantations are carried out each year in Sweden, and about 100,000 in the world. The damaged and cloudy cornea that is turning the patient blind is replaced with a healthy, transparent one. But the procedure requires a donated cornea, and there is a severe shortage of donated material. This is particularly the case throughout the world, where religious or political views often hinder the use of donated material. Scientists at the Sahlgrenska Academy, University of Gothenburg, have taken the first step towards replacing donated corneas with corneas cultivated from stem cells. Scientists Charles Hanson and Ulf Stenevi have used defective corneas obtained from the ophthalmology clinic at Sahlgrenska University Hospital in Mölndal. Their study is now published in the journal Acta Ophthalmologica, and shows how human stem cells can be caused to develop into what are known as “epithelial cells” after 16 days’ culture in the laboratory and a further 6 days’ culture on a cornea. It is the epithelial cells that maintain the transparency of the cornea.

“Similar experiments have been carried out on animals, but this is the first time that stem cells have been grown on damaged human corneas. It means that we have taken the first step towards being able to use stem cells to treat damaged corneas,” says Charles Hanson. “If we can establish a routine method for this, the availability of material for patients who need a new cornea will be essentially unlimited. Both the surgical procedures and the aftercare will also become much more simple,” says Ulf Stenevi. Only a few clinics are currently able to transplant corneas. Many of the transplantations in Sweden are carried out at the ophthalmology clinic at Sahlgrenska University Hospital, Department of Ophthalmology, Mölndal.

Science Daily
March 20, 2012

Original web page at Science Daily

Researcher Thijs Meenink at Eindhoven University of Technology (TU/e) has developed a smart eye-surgery robot that allows eye surgeons to operate with increased ease and greater precision on the retina and the vitreous humor of the eye. The system also extends the effective period during which ophthalmologists can carry out these intricate procedures. Meenink defended his PhD thesis on Oct. 31 for his work on the robot, and intends later to commercialize his system. Eye operations such as retina repairs or treating a detached retina demands high precision. In most cases surgeons can only carry out these operations for a limited part of their career. “When ophthalmologists start operating they are usually already at an advanced stage in their careers,” says Thijs Meenink. “But at a later age it becomes increasingly difficult to perform these intricate procedures.” The new system can simply filter-out hand tremors, which significantly increases the effective working period of the ophthalmologist.

The robot consists of a ‘master’ and a ‘slave’. The ophthalmologist remains fully in control, and operates from the master using two joysticks. This master was developed in an earlier PhD project at TU/e by dr.ir. Ron Hendrix. Two robot arms (the ‘slave’ developed by Meenink) copy the movements of the master and carry out the actual operation. The tiny needle-like instruments on the robot arms have a diameter of only 0.5 millimeter, and include forceps, surgical scissors and drains. The robot is designed such that the point at which the needle enters the eye is always at the same location, to prevent damage to the delicate eye structures. Meenink has also designed a unique ‘instrument changer’ for the slave allowing the robot arms to change instruments, for example from forceps to scissors, within only a few seconds. This is an important factor in reducing the time taken by the procedure. Some eye operations can require as many as 40 instrument changes, which are normally a time consuming part of the overall procedure. The surgeon’s movements are scaled-down, for example so that each centimeter of motion on the joystick is translated into a movement of only one millimeter at the tip of the instrument. “This greatly increases the precision of the movements,” says Meenink.

The master also provides haptic feedback. Ophthalmologists currently work entirely by sight — the forces used in the operation are usually too small to be felt. However Meenink’s robot can ‘measure’ these tiny forces, which are then amplified and transmitted to the joysticks. This allows surgeons to feel the effects of their actions, which also contributes to the precision of the procedure. The system developed by Meenink and Hendrix also offers ergonomic benefits. While surgeons currently are bent statically over the patient, they will soon be able to operate the robot from a comfortable seated position. In addition, the slave is so compact and lightweight that operating room staff can easily carry it and attach it to the operating table. Ophthalmologist prof.dr. Marc de Smet (AMC Amsterdam), one of Meenink’s PhD supervisors, is enthusiastic about the system — not only because of the time savings it offers, but also because in his view the limits of manual procedures have now been reached. “Robotic eye surgery is the next step in the evolution of microsurgery in ophthalmology, and will lead to the development of new and more precise procedures,” de Smet explains. Both slave and master are ready for use, and Meenink intends to optimize them in the near future. The first surgery on humans is expected within five years. He also plans to investigate the market opportunities for the robot system. Robotic eye surgery is a new development; eye surgery robots are not yet available on the market.

Science Daily
November 15, 2011

Original web page at Science Daily

Two new studies add to the growing body of evidence that a new approach to cataract surgery may be safer and more efficient than today’s standard procedure. The new approach, using a special femtosecond laser, is FDA-approved, but not yet widely available in the United States. It’s one of the hottest topics at the 115th Annual Meeting of the American Academy of Ophthalmology. Research reported Oct. 23 by William W. Culbertson, MD, of the Bascom Palmer Eye Institute at the University of Miami School of Medicine, and by Mark Packer, MD, of Oregon Health and Sciences University, confirms several advantages of laser cataract surgery. Dr. Culbertson’s team studied how pre-treating cataracts with the femtosecond laser affected the level of ultrasound energy needed to soften the cataracts. This emulsification is performed so that the cataracts can be easily suctioned out. Surgeons want to use the lowest possible level of ultrasound energy, since in a small percentage of patients it is associated with slower recovery of good vision after surgery and/or problems with the cornea, which is the clear outer layer of the eye. Ideally, in appropriate cases, ultrasound use would be eliminated altogether.

In Dr. Culbertson’s prospective, randomized study, 29 patients had laser cataract surgery with a femtosecond laser in one eye and the standard cataract procedure, called phacoemulsification, in the other. Laser surgery included: a laser capsulotomy, which is a circular incision in the lens capsule, followed by laser lens fragmentation, then ultrasound emulsification and aspiration. Lens fragmentation involved using the laser to split the lens into sections and then soften it by etching cross-hatch patterns on its surface. Standard surgery included a manual incision, followed by ultrasound emulsification and aspiration. After cataract removal by either method, intraocular lenses were inserted into eyes to replace the natural lens and provide appropriate vision correction for each patient. The use of ultrasound energy use was reduced by 45 percent in the laser pre-treated eyes compared with the eyes that received the standard cataract surgery procedure. Also, surgical manipulation of the eye was reduced by 45 percent in eyes that received laser pre-treatment as compared to manual standard surgery. This study involved the most common types of cataracts, those graded 1- 4. Dr. Culbertson notes that these findings may not apply to higher grade cataracts.

“In clinical practice, surgeons would expect safer, faster cataract surgery when laser pre-treatment is performed before cataract removal,” said Dr. Culbertson. “The combination of precision and simplification that is possible with the femtosecond laser represents a major advance for this surgery.” Dr. Packer’s team at the Oregon Health and Sciences University in Portland, Oregon, assessed the safety of laser cataract surgery in terms of loss of corneal endothelial cells, as measured after cataract surgery. Measuring endothelial cell loss is one of the most important ways to assess the safety of new cataract surgery techniques and technology. These cells preserve the cornea’s clarity, and since they don’t regenerate, they must last a lifetime. Dr. Packer’s study found that when laser lens fragmentation was used in 225 eyes, there was no loss of endothelial cells, while the 63 eyes that received standard treatment had cell loss of one to seven percent. “Our finding, that laser lens fragmentation appears to protect corneal endothelial cells, represents a significant benefit of this new surgery,” said Dr. Packer. “This procedure is safer than standard cataract treatment and is likely to mean better vision and fewer eye health concerns for cataract patients, over the long term.”

Earlier studies of femtosecond laser cataract surgery found other benefits. The laser allows the surgeon to make smaller, more precise incisions and to perform improved capsulotomies, which is the removal of part of the lens capsule that make intraocular lens (IOL) placement more secure. This reduces the chance that an IOL will later become displaced. Also, laser cataract surgery appears to improve results in patients who opt for advanced technology IOLs, plus corrective corneal incisions, to achieve good all-distance vision. Femtosecond lasers have been used by ophthalmologists for years in refractive surgery such as LASIK, in-corneal transplants, and in other procedures. In 2009, a new type of femtosecond laser that could reach deep enough into the eye to be used in cataract removal was approved by the FDA.

Science Daily
November 15, 2011

Original web page at Science Daily

An implant that releases the medication dexamethasone within the eye appears safe and effective for the treatment of some types of uveitis (swelling and inflammation in the eye’s middle layer), according to a report posted online that will appear in the May print issue of Archives of Ophthalmology, one of the JAMA/Archives journals. “Uveitis refers to a group of intraocular inflammatory diseases that cause 10 percent to 15 percent of blindness in the developed world,” the authors write as background information in the article. “Despite advances in immunosuppressive treatments, corticosteroids remain the mainstay of therapy.” However, some patients cannot tolerate or do not respond to systemic corticosteroids, in part because the medications do not cross the blood-retinal barrier. Eye drops containing corticosteroids are effective only for anterior uveitis, closer to the front of the eye. Injections of corticosteroids directly into the eye have been effective in forms of intermediate or posterior uveitis, but require repeated treatments every two to three months and are associated with cataracts and other adverse effects.

To address these issues, an intravitreal (within the vitreous fluid of the eye), bioerodible, sustained-release implant has been developed to deliver a glucocorticoid medication, dexamethasone, to the back of the eye chamber. Careen Lowder, M.D., Ph.D., of the Cleveland Clinic Cole Eye Institute, and colleagues in the Ozurdex HURON Study Group conducted a 26-week randomized controlled trial involving 229 patients with intermediate or posterior uveitis. A total of 77 patients received an implant with a 0.7-milligram dose of dexamethasone, 76 received an implant with a 0.35-milligram dose and 76 underwent a sham procedure which followed the same protocol but used a needleless applicator. After eight weeks, the eyes were evaluated for the presence and degree of vitreous haze, or inflammation that obscures visualization. Vitreous haze was scored from zero to four, with zero indicating no inflammation and four indicating the most severe inflammation, obscuring the optic nerve. At the beginning of treatment, participants had an average vitreous haze score of two.

At the eight-week follow-up, a vitreous haze score of zero was observed in 47 percent of eyes with the 0.7-milligram implant, 36 percent of those with the 0.35-milligram implant and 12 percent of those who underwent the sham procedure. There was no significant difference between the two treatment doses, and the benefit associated with the implant persisted through the 26-week study. In addition, the percentage of eyes that achieved at least a 15-letter improvement in visual acuity was two- to six-fold greater in both implant groups than in the control group throughout the study. “Typically, the most common adverse events associated with intravitreal corticosteroids, which may have impacted use in the past, including increases in intraocular pressure [pressure within the eye] and cataract. On any given follow-up visit in the present study, substantial increases in intraocular pressure (to 25 millimeters of mercury or greater) occurred in less than 10 percent of treated eyes,” the authors write. In addition, only one of 62 phakic (with lenses) eyes required surgery to remove a cataract.

“In conclusion, the present study demonstrated that in patients with non-infectious intermediate or posterior uveitis, a single dose of the dexamethasone intravitreal implant was well tolerated and produced significant improvements in intraocular inflammation and visual acuity that persisted for six months,” the authors conclude. “Overall, the 0.7-milligram dexamethasone intravitreal implant demonstrated greater efficacy than the 0.35-milligram dexamethasone intravitreal implant, with similar safety.”

Science Daily
January 24, 2011

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