For patients with macular degeneration, new hope for restored sight
An implant, combined with the glasses and tiny video camera modeled in this photo, could improve the eyesight of millions of people with degenerative eye diseases in the coming years.
For millions of people with macular degeneration, treatment options are slim. The disease causes loss of central vision, which allows us to see straight ahead, and is highly dependent on age, with people over 75 at approximately 30% risk of developing the disorder. The BrightFocus Foundation estimates 11 million people in the U.S. currently have one of three forms of the disease.
Recently, ophthalmologists including Daniel Palanker at Stanford University published research showing advances in the PRIMA retinal implant, which could help people with advanced, age-related macular degeneration regain some of their sight. In a feasibility study, five patients had a pixelated chip implanted behind the retina, and three were able to see using their remaining peripheral vision and—thanks to the implant—their partially restored central vision at the same time.
Should people with macular degeneration be excited about these results?
“Every week, if not every day, patients come to me with this question because it's devastating when they lose their central vision,” says retinal surgeon Lynn Huang. About 40% of her patients have macular degeneration. Huang tells them that these implants, along with new medications and stem cell therapies, could be useful in the coming years.
“The goal here is to replace the missing photoreceptors with photovoltaic pixels, basically like little solar panels,” Palanker says.
That implant, a pixelated chip, works together with a tiny video camera on a specially designed pair of eyeglasses, which can be adjusted for each patient’s prescription. The video camera relays processed images to the chip, which electrically stimulates inner retinal neurons. These neurons, in turn, relay information to the brain’s visual cortex through the optic nerve. The chip restores patients’ central sight, but not completely. The artificial vision is basically monochromatic (whitish-yellowish) and fairly blurry; patients were still legally blind even after the implant, except when using a zoom function on the camera, but those with proper chip placement could make out large letters.
“The goal here is to replace the missing photoreceptors with photovoltaic pixels, basically like little solar panels,” Palanker says. These pixels, located on the implanted chip, convert light into pulsed electrical currents that stimulate retinal neurons. In time, Palanker hopes to improve the chips, resulting in bigger boosts to visual acuity.
The pixelated chips are surgically implanted during a process Palanker admits is still “a surgical learning curve.” In the study, three chips were implanted correctly, one was placed incorrectly, and another patient’s chip moved after the procedure; he did not follow post-surgical recommendations. One patient passed away during the study for unrelated reasons.
University of Maryland retinal specialist Kenneth Taubenslag, who was not involved in the study, said that subretinal surgeries have become less common in recent years, but expects implants to spur improvements in these techniques. “I think as people get more experience, [they’ll] probably get more reliable placement of the implant,” he said, pointing out that even the patient with the misplaced chip was able to gain some light perception, if not the same visual acuity as other patients.
Retinal implants have come under scrutiny lately. IEEE Spectrum reported that Second Sight, manufacturer of the Argus II implant used for people with retinitis pigmentosa, a genetic disease that causes vision loss, would no longer support the product. After selling hundreds of the implants at $150,000 apiece, company leaders announced they’d “decided to pursue an orderly wind down” of Second Sight in March 2020 in the wake of financial issues. Last month, the company announced a merger, shifting its focus to a new retinal implant, raising questions for patients who have Argus II implants.
Retinal surgeon Eugene de Juan of the University of California, San Francisco, was involved with early studies of the Argus implants, though his participation ended over a decade ago, before the device was marketed by Second Sight. He says he would consider recommending future implants to patients with macular degeneration, given the promise of the technology and the lack of other alternatives.
“I tell my patients that this is an area of active research and development, and it's getting better and better, so let's not give up hope,” de Juan says. He believes cautious optimism for Palanker’s implant is appropriate: “It's not the first, it's not the only, but it's a good approach with a good team.”
Sexually Transmitted Infections are on the rise. This drug could stop them.
Cases of gonorrhea, chlamydia and syphilis soared last year, but researchers are finding that a drug known as doxy seems to reduce the number of infections.
Sexually transmitted infections (STIs) are surging across the U.S. to 2.5 million cases in 2021 according to preliminary data from the CDC. A new prevention and treatment strategy now in clinical trials may provide a way to get a handle on them.
It's easy to overlook the soaring rates of gonorrhea, chlamydia, and syphilis because most of those infections have few or no symptoms and can be identified only through testing. But left untreated, they can lead to serious damage to nerves and tissue, resulting in infertility, blindness, and dementia. Infants developing in utero are particularly vulnerable.
Covid-19 played havoc with regular medical treatment and preventive care for many health problems, including STIs. After formal lockdowns ended, many people gradually became more socially engaged, with increases in sexual activity, and may have prioritized these activities over getting back in touch with their doctors.
A second blow to controlling STIs is that family planning clinics are closing left and right because of the Dobbs decision and legislation in many states that curtailed access to an abortion. Discussion has focused on abortion, but those same clinics also play a vital role in the diagnosis and treatment of STIs.
Routine public health is the neglected stepchild of medicine. It is called upon in times of crisis but as that crisis resolves, funding dries up. Labs have atrophied and personnel have been redirected to Covid, “so access to routine screening for STIs has been decimated,” says Jennifer Mahn, director of sexual and clinical health with the National Coalition of STD Directors.
A preview of what we likely are facing comes from Iowa. In 2017, the state legislature restricted funding to family health clinics in four counties, which closed their doors. A year later the statewide rate of gonorrhea skyrocketed from 83 to 153.7 cases per 100,000 people. “Iowa counties with clinic closures had a significantly larger increase,” according to a study published in JAMA. That scenario likely is playing out in countless other regions where access to sexual health care is shrinking; it will be many months before we have the data to know for sure.
A decades-old antibiotic finds a new purpose
Using drugs to protect against HIV, either as post exposure prophylaxis (PEP) or pre-exposure prophylaxis (PrEP), has proven to be quite successful. Researchers wondered if the same approach might be applied to other STIs. They focused on doxycycline, or doxy for short. One of the most commonly prescribed antibiotics in the U.S., it’s a member of the tetracycline family that has been on the market since 1967. It is so safe that it’s used to treat acne.
Two small studies using doxy suggested that it could work to prevent STIs. A handful of clinical trials by different researchers and funding sources set out to generate the additional evidence needed to prove their hypothesis and change the standard of care.
Senior researcher Victor Omollo, with the Kenya Medical Research Institute, noted, “These are prevention interventions that women can control on their own without having to seek or get consent from another person,” as is the case with condom use.
The first with results is the DoxyPEP study, conducted at two sexual health clinics in San Francisco and Seattle. It drew from a mix of transgender women and men who have sex with men, who had at least one diagnosed STI over the last year. The researchers divided the participants into two groups: one with people who were already HIV-positive and engaged in care, while the other group consisted of people who were on PrEP to prevent infection with HIV. For the active part of the study, a subset of the participants received doxy, and the rest of the participants did not.
The researchers intentionally chose to do the study in a population at the highest risk of having STIs, who were very health oriented, and “who were getting screened every three months or so as part of their PrEP program or their HIV care program,” says Connie Celum, a senior researcher at the University of Washington on the study.
Each member of the active group was given a supply of doxy and asked to take two pills within 72 hours of having sex where a condom was not used. The study was supposed to run for two years but, in May, it stopped halfway through, when a safety monitoring board looked at the data and recommended that it would be unethical to continue depriving the control group of the drug’s benefits.
Celum presented these preliminary results from the DoxyPEP study in July at the International AIDS Conference in Montreal. “We saw about a 56 percent reduction in gonorrhea, about 80 percent reduction in chlamydia and syphilis, so very significant reductions, and this is on a per quarter basis,” she told a later webinar.
In Kenya, another study is following a group of cisgender women who are taking the same two-pill regimen to prevent HIV, and the data from this research should become available in 2023. Senior researcher Victor Omollo, with the Kenya Medical Research Institute, noted that “these are prevention interventions that women can control on their own without having to seek or get consent from another person,” as is the case with condom use, another effective prevention tool.
Antibiotic resistance
Antibiotic resistance is a potentially big concern. About 25 percent of gonorrhea strains circulating in the U.S. are resistant to the tetracycline class of drugs, including doxy; rates are higher elsewhere. But resistance often is a matter of degree and can be overcome with a larger or longer dose of the drug, or perhaps with a switch to another drug or a two-drug combination.
Research has shown that an established bacterial infection is more difficult to treat because it is part of a biofilm, which can leave only a small portion or perhaps none of the cell surface exposed to a drug. But a new infection, even one where the bacteria is resistant to a drug, might still be vulnerable to that drug if it's used before the bacterial biofilm can be established. Preliminary data suggests that may be the case with doxyPEP and drug resistant gonorrhea; some but not all new drug resistant infections might be thwarted if they’re treated early enough.
“There are some tradeoffs” to these interventions, Celum says, and people may disagree on the cost of increased resistance balanced against the benefits of treating the STIs and reducing their spread within the community.
Resistance does not seem to be an issue yet for chlamydia and syphilis even though doxy has been a recommended treatment for decades, but a remaining question is whether broader use of doxy will directly worsen antibiotic resistance in gonorrhea, or promote it in other STIs. And how will it affect the gut microbiome?
In addition, Celum notes that we need to understand whether doxy will generate mutations in other bacteria that might contribute to drug resistance for gonorrhea, chlamydia or syphilis. The studies underway aim to provide data to answer these questions.
“There are some tradeoffs” to these interventions, Celum says, and people may disagree on the cost of increased resistance balanced against the benefits of treating the STIs and reducing their spread within the community. That might affect doctors' willingness to prescribe the drug.
Turning research into action
The CDC makes policy recommendations for prevention services such as taking doxy, requiring some and leaving others optional. Celum says the CDC will be reviewing information from her trial at a meeting in December, but probably will wait until that study is published before making recommendations, likely in 2023. The San Francisco Department of Public Health issued its own guidance on October 20th and anecdotally, some doctors around the country are beginning to issue prescriptions for doxy to select patients.
About half of new STIs occur in young people ages 15 to 24, a group that is least likely to regularly see a doctor. And sexual health remains a great taboo for many people who don't want such information on their health record for prying parents, employers or neighbors to find out.
“People will go out of their way and travel extensive distances just to avoid that,” says Mahn, the National Coalition director. “People identify locations where they feel safe, where they feel welcome, where they don't feel judged,” Mahn explains, such as community and family planning clinics. They understand those issues and have fees that vary depending on a person’s ability to pay.
Given that these clinics already are understaffed and underfunded, they will be hard pressed to expand services covering the labor intensive testing and monitoring of a doxyPEP regimen. Sexual health clinics don't even have a separate line item in the federal budget for health. That is something the National Association of STI Directors is pushing for in D.C.
DoxyPEP isn't a panacea, and it isn't for everyone. “We really want to try to reach that population who is most likely going to have an STI in the next year,” says Celum, “Because that's where you are going to have the biggest impact.”
The Friday Five: The plain solution to holiday stress?
In this week's Friday Five, research on how to improve your working memory, the plain old solution to stress, rise of the robot surgeon, tomato brain power, the gut connection to health after strokes - and more.
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
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Here are the promising studies covered in this week's Friday Five:
- How to improve your working memory
- A plain old solution to stress
- Progress on a deadly cancer for first time since 1995*
- Rise of the robot surgeon
- Tomato brain power
And in an honorable mention this week, new research on the gut connection to better brain health after strokes.
* The methodology for this study has come under scrutiny here.