Saturday, June 27, 2015

Can the Weather Affect Your Vision?

It’s the stereotypical front-porch scene: a couple of old-timers complaining about aches and pains, and then predicting  a storm is in on the horizon because of a feeling in a joint or bone.

It’s not just old knees or a beat-up shoulder than can send signals in advance of weather – some people report experiencing symptoms in their eyes as weather gets ready to change. Those issues seem to be most often accompanied by tingling, dizziness, and being mentally flustered. But whether in the eye or joints, what about an impending rain could cause any discomfort at all?

As a storm approaches, the area’s atmospheric pressure drops. This is what the weathermen talk about on the news as they explain that the low pressure system heading your way will be ruining your weekend plans or canceling school tomorrow. Atmospheric pressure is essentially the weight of the air in the atmosphere, and when a big storm is heading in, that can pressure drop — sometimes quickly enough to trigger quite a reaction.

A drop in pressure is a bit like a scuba diver coming up from extreme depths, except on a molecular level. Without the pressure of all that water, divers are required to wait for pre-determined amounts of time to decompress so air bubbles in their blood don’t expand and give them a painful and potentially fatal condition called decompression sickness (more commonly called the bends). Some doctors think that changes in the atmospheric pressure on land — such as those brought on by an impending change in the weather — can cause people with chronic pain or certain other conditions to experience sensations because of the minuscule pressure difference allowing cells to expand just a bit. It’s the same reason people’s feet swell on commercial flights — though the cabin is pressurized, it’s a little less so than you’d experience at home.

While sensitivity to pressure changes in the eyes doesn’t appear to cause more than a little discomfort and annoyance for people in normal environments, at extreme altitude it can be a different story. In part because atmospheric pressure is lower at altitude, some alpinists, soldiers, trekkers and others at very high altitudes report bleeding in the eye, known as High-Altitude Retinal Hemorrhaging. Often, the condition accompanies other signs of acute mountain sickness or other altitude-related malady like cerebral edemas, but the eye issues can also happen on their own. The good news is that a trip into the Catskills isn’t likely to trigger such a reaction. You’d probably need to be hiking high into the Himalayas or Andes to be at risk for such an issue, though people sometimes report altitude issues in places like Colorado.

So does a light head and slightly blurred vision mean there’s rain in the forecast? Maybe, but regardless you should have any unusual symptoms checked out by an eye care professional before letting the neighbors know that turning on the sprinklers is a waste of time.


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Friday, June 19, 2015

What Is The Difference Between LASEK And LASIK?

LASIK and LASEK share some things in common and have certain differences. The goal of both surgeries is to change the shape and power of the front part of the eye called the cornea, which is the clear window of tissue overlying the colored iris and pupil, such that light travels through the cornea and then the lens, and will then be focused on the retina, achieving clear vision.

This is accomplished in both surgeries, LASIK and LASEK, using a device known as an excimer laser. This cool beam, computer driven, ultraviolet laser changes the shape of the cornea by a chemical process known as photoablation. In LASIK, a corneal flap is created followed by application of the laser. In LASEK, the outer layer of the cornea is first removed or loosened using a dilute alcohol solution. It is then brushed away followed by the application of the laser, and then in some patients, the outer layer may be repositioned, and in others it may be discarded, but in both conditions the outer layer will rejuvenate and replace itself in three to five days. Visual recovery is faster in LASIK than LASEK; however the end result is very similar and the differences are so minor not to be clinically significant.

The recommendation as to proceed with LASIK or LASEK can be only be made by your ophthalmologist after an examination specific to your measurements. For example, if you have a thin cornea or a particularly dry eye, or participate in contact sports, it’s possible that the ophthalmologist may recommend LASEK versus LASIK. In other cases, LASIK may be recommended because of the faster visual recovery.

Source: ABC News

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Thursday, June 11, 2015

Scientists Set Sights on 1st Whole-Eye Transplant

In the world of 21st-century medicine, organ transplantation is nothing new.

The first kidney transplant took place in 1950, followed by the first liver transplant in 1963 and the first human heart transplant in 1967. By 2010, doctors had even managed the transplantation of a patient’s entire face.

One major organ still eludes the transplant surgeon, however: the entire human eye. But if one team of U.S. scientists has its way, that dream may become reality, too.

“Until recently, eye transplants have been considered science fiction,” said Dr. Vijay Gorantla, an associate professor of surgery in the department of plastic surgery at the University of Pittsburgh. “People said it was crazy, bonkers.”

However, “with what we now know about transplantation and, more importantly, nerve regeneration, we are finally at the point where we can have real confidence that this is something that actually can be pursued and eventually achieved,” he said.

Whole-eye transplants would be of enormous benefit for many of the 180 million blind or severely visually disabled people around the world, including nearly 3.5 million Americans, experts say.

“Macular degeneration and glaucoma are the root cause of much the world’s visual impairment,” explained Dr. Jeffrey Goldberg, director of research at the Shiley Eye Center at University of California, San Diego.

Certainly, there are therapies that often help restore sight in these cases, or in people who’ve lost sight through injury. “But for some people the eye is too damaged or too far gone,” Goldberg said. “For patients with a devastating eye injury where there’s no remaining connective optic nerve — or perhaps not even an eyeball in their eye socket — restorative approaches are simply not enough.”

In these cases, transplantation of a healthy donor eye would be a solution. “It’s a scientific long shot,” Goldberg said. “But it’s a very attractive long shot.”

So, Gorantla and Goldberg — and their two universities — have teamed up to push whole-eye transplantation from theory into practice. The effort is funded by the U.S. Department of Defense.

One of the biggest challenges is how to regenerate and regrow delicate optical nerves.

“The chief problem,” Goldberg explained, “is that when you switch out an eyeball you have to completely cut all connections between the optic nerve and the eye. So then you need to reconnect the donor eye’s nerve fibers back to the recipient’s brain in order to achieve vision restoration. But we know that once you make that cut, the nerve fibers just do not regrow on their own. That doesn’t happen automatically.”

“That’s what distinguishes an eye transplant from most other types of transplants,” Gorantla added. In other organ transplants, the chief hurdle is simply reconnecting a proper blood supply. “For example, if you get the plumbing connected and the blood going, then a transplanted heart will beat in the recipient patient immediately,” Gorantla said.

“But an eye transplant actually has more parallels with a hand or face transplant,” he said. The eye may appear healthy because of a renewed blood supply, but without reconnecting the optic nerve, “there’s no motor activity and no sensation or eyesight,” Gorantla said. “The result is functionless and lifeless.”

Luckily, various laboratories “have made significant progress” in fostering the long distance regrowth of nerve fibers, Goldberg said. “In animals with optic nerve injury or degeneration we’ve even started to see fibers regrow all the way back to the brain,” he noted.

The regeneration of cells called retinal ganglia cells — key to achieving discernible vision — has also met with recent success in a lab setting. “The recent indications that such nerve generation is actually possible raises optimism that eye transplantation can really be viable,” said Gorantla, who is also administrative medical director of the Pittsburgh Reconstructive Transplant Program at the University of Pittsburgh Medical Center.

Still, any first attempt at a whole-eye transplant in humans remains years away, the experts cautioned.

“There’s a significant amount of work to be done before anything like this can be tried on patients,” Goldberg said. “But when you survey people, losing one’s vision comes in just a smidge below death as a thing we fear. There are few things people value more than their vision, so while it may be audacious, it’s worth the effort.”


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Wednesday, June 3, 2015

Are You Making These 5 Contact Lens Mistakes?

It might seem tempting (and oh-so-easy) to crash on the couch or hop in the shower with your contacts in, but doing so can actually put your eyes at serious risk.

We talked to Thomas Steinemann, M.D., a professor of ophthalmology at Case Western Reserve University and a spokesperson for the American Academy of Ophthalmology, about some of the most common mistakes the 36 million Americans who wear contact lenses make. Read on for how to avoid them – and why it’s important you do.

The Mistake: Sleeping in your contacts

Although some professionals and contact manufacturers say that it’s okay to sleep in certain types of lenses, Steinemann does not recommend it. Your cornea, the outside layer of your eye that the contact covers, needs oxygen. Wearing contacts deprives the eye of that oxygen, and sleeping in your lenses exacerbates the problem. At best, overnight wear will likely cause irritation and discomfort. At worst, it could lead to a serious infection. According to an overview of surveys by the Journal of Optometry, sleeping in contact lenses seemed to be “the main cause of microbial keratitis,” a type of eye infection.

The Mistake: Taking a shower or a swim in your contacts

It might seem like no big deal, but swimming and showering with your contacts in is a bad idea, says Steinemann. Most water sources – including lakes, pools, hot tubs, and bathroom sinks – contain the microorganism Acanthamoeba. If it finds its way into your eyes, acanthamoeba can cause an extremely painful infection and potentially even lead to blindness. The treatment is long and difficult, Steinemann says.

Contact lens wearers are at greater risk for a number of reasons (the same Journal of Optometry paper says that contact lenses may account for 95 percent of acanthamoeba eye infections). The acanthamoeba is particularly attracted to the contact lens: Contacts cause minor scratches on the cornea, which make it more vulnerable to bacteria and microorganisms of all kinds. In addition, any bacteria living on the surface of the contact serve as a food source for the acanthamoeba, allowing it to survive in your eye.

The Mistake: Using water to clean your lenses

Even riskier than swimming while wearing contacts is storing your lenses in tap water. “Even though tap water is pure enough to drink, it’s not sterile,” Steinemann says. Acanthamoeba also lives in tap water, so soaking lenses in water from the sink is an invitation to infection. Instead, you should always store them in solution.

It’s also important to wash your hands before putting your lenses in and taking them out – and never leave old solution from the day before in the case (use all new solution, don’t just top it off). Rub and rinse the contacts with solution after each use.

The Mistake: Using a case for too long without replacing it

Steinemann recommends cleaning your lens case thoroughly with solution every day, and replacing the case every month. (The American Optometric Association advises replacing it at least every three months.)

And don’t cut corners by throwing your contacts case in the dishwasher: “There’s food in your dishwasher. It’s not like it’s a sterile place,” says Dr. Anne Sumers, an ophthalmologist and spokesperson for American Academy of Ophthalmology. Steinemann also warns against putting your case in the dishwasher, citing concerns about the residues from dish soap that could end up on the case or lens. Clean the case with solution and let it air dry until the next day.

This may sound complicated, but it’s important. An old case is “a set up for germs growing on the case and on the lens,” Steinemann says. Besides the general griminess of a six-month-old contact case that you can probably see, invisible germs and bacteria are likely living there, too.

And keeping contacts and their cases clean and bacteria-free reduces vulnerability to all types of infection. A 2012 study in the journal Ophthalmology showed that the risk of eye infection was 6.4 times greater in those who didn’t properly clean their contact cases and 5.4 times greater in those who didn’t replace their cases frequently enough.

The Mistake: Wearing your contacts way past their expiration date

“Most people will admit that they keep their lenses longer,” Steinemann says, than the recommended period. This is a similar hazard to a worn-out case: Old lenses become coated with germs and the build-up of solution, proteins, and other residues, Steinemann says. This will make the lenses uncomfortable and can lead to infection.


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