Femtosecond Laser May Reduce Risk of Myopic Regression after LASIK

A significant fraction of LASIK patients may experience myopic regression after LASIK. When this occurs, the results of LASIK will decline toward increased myopia (nearsightedness) after treatment. It’s not known exactly what is the frequency of this condition, but some studies have suggested it might be as high as 20% during the first six months and as high as 25% after a year. Patients with high myopia (at least 10 diopters) are at the greatest risk for this complication.

A recent study suggests that the use of the microkeratome may be partly to blame for this, and that LASIK patients may be more likely to retain the quality of their LASIK results if the procedure is performed using a femtosecond laser. The study, published in the Journal of Cataract and Refractive Surgery looked at the long-term results of 786 LASIK patients, 377 who had LASIK performed with a microkeratome, 409 performed with a femtosecond laser. Follow-ups were performed for both groups at one week and 12 months after surgery.

Researchers defined myopic regression as a combination of a myopic shift of 0.5 diopters (about 1 line on the Snellen chart) or more with residual myopia of 0.5 diopters or less. Using this definition, the risk for myopic regression after LASIK with a microkeratome was 67%, compared to 44% risk for femtosecond laser LASIK.

This study is part of the growing body of evidence that, although subtle, femtosecond lasers may actually result in significantly better LASIK results than microkeratomes.

To discuss a possible LASIK procedure with a doctor, please contact a local ophthalmologist.

Are You a Candidate for PRK (Photorefractive Keratectomy)?

PRK (Photorefractive Keratectomy) is a laser vision correction procedure that can effectively treat myopia, hyperopia, and astigmatism. PRK achieves vision correction in the same basic way that LASIK does, with one significant difference: PRK does not create a corneal flap. Instead, PRK removes the entire surface layer of your eye (the epithelium) using in order to reshape the stoma layer beneath it. After PRK surgery, the epithelium layer will regenerate and heal on its own.

Because of this, PRK is a good option for patients who have corneas that are too thin for LASIK flap creation. The ideal PRK candidate should:

  • Have good ocular health
  • Be 18+ years old
  • Have a year or more of stable eye examinations
  • Not be pregnant (or planning a pregnancy in the near future)

Since the epithelium layer is entirely removed during PRK treatment, your recovery period will last longer than the healing period for LASIK, but PRK is capable of achieving the same quality of results. Anesthetic eyedrops are used to keep you comfortable during the procedure, and you will be provided with post-surgical eyedrops to help manage any lingering discomfort. Unlike LASIK, there is no need for a blade to be used on your eye.

If you have further questions about the PRK procedure, please contact an experienced eye surgeon in your area today to schedule an initial consultation.

Preventing Eye Strain

Eye strain – technically referred to as “asthenopia” – is becoming increasingly common in recent years as we continue to rely on countless forms of screen-based technology. Eye strain can occur in one or both of your eyes, and it often leads to chronic headaches, blurred vision, dry or burning eyes, and sore neck muscles.

While eye strain usually goes away with sleep and rest, it is sometimes a symptom of a larger underlying problem, such as eye muscle imbalance or a refractive error. If you frequently suffer from eye strain, you should visit your eye doctor to be tested for additional problems.

The number one cause of eye strain today is computer vision syndrome (CVS), but eye strain is also often caused by:

  • Reading
  • Failure to blink
  • Visual tasks performed in dim lighting

The pain associated with eye strain can be significantly reduced if you take the time to perform eye exercises whenever you are sitting at a computer or performing visually intensive work. It is best to take frequent breaks from your computer throughout the day. Try to perform eye exercises every 20 minutes. Closing your eyes for a bit and blinking frequently can also help reduce your symptoms.  If your eye strain is caused by an underlying problem, your ophthalmologist may prescribe eye drops, glasses, or contacts to help you.

If you are suffering from symptoms of eye strain, contact an experienced ophthalmologist in your area today to schedule an initial consultation.

PRK Safer than LASIK for Retreating Radial Keratotomy

For those who need radial keratotomy (RK) re-treatments, it has been reported by the RK Re-treatment Study that PRK is safer than LASIK.

The RK Re-treatment Study group, led by ophthalmologists, looked at 221 procedures over a 12 year period between 1997 and 2010 from six different US surgical centers. All but three LASIK procedures were done conventionally, while two-thirds of the PRK procedures were conventional. The other one-third were wavefront-guided custom PRK. (Wavefront-treatment did not become popular until around 2005.) Refractive errors between PRK and LASIK patients were roughly the same.

Three to six months after eye surgery, both conventional LASIK and wavefront-guided PRK showed better at keeping best-corrected visual acuity in patients than was conventional PRK. Nearly 80% of all patients showed better than 20/40 vision after eye surgery.

However, for patients who needed to be retreated, there were complications in 12% of the custom LASIK patients, while only 4% of PRK patients had complications. Complications included ectasia in the LASIK group, which required penetrating keratoplasty. Two patients in the PRK group required both eyes needing phototherapeutic keratectomy due to “postoperative haze.” Retreatment gave these patients 20/20 and 20/25 vision respectively.

The RK Re-treatment Study recommends further evaluation in this area of laser vision correction. This may be especially important due to the increasing number of people seeking vision correction surgery.

If you are interested in finding out more about PRK or LASIK, please find a doctor in your area through eyes.com today.

Will Phakic IOLs Be Approved for Hyperopia?

Phakic IOLs are a type of intraocular lens that is used to help your eye attain the proper focus. Unlike the lenses used in cataract surgery, which are sometimes called aphakic IOLs, these lenses do not replace your eye’s natural crystalline lens. Instead, they are helper lenses, sometimes described as “implantable contact lenses.”

Phakic IOLs have been approved for the treatment of myopia by the US Food and Drug Administration (FDA) since 2003. However, they have not been approved for the treatment of hyperopia. According to industry representatives, studies of phakic IOLs for treatment of hyperopia are ongoing, but will they ever be approved?

Concerns with Phakic IOLs for Hyperopia

There are two significant concerns that have delayed the approval of phakic IOLs for hyperopia. Both relate to the narrow anterior chamber of hyperopes, the part of the eye between the iris and the cornea, where some phakic IOLs are placed. First, there is concern that the IOL will abrade the endothelium, the innermost layer of the cornea, which could result in a condition similar to Fuchs’ Dystrophy. Second, there is concern that implantation of a phakic IOL in an already crowded anterior chamber could increase the risk of closed angle, or acute glaucoma.

Both of these risks are likely very rare, but because of the seriousness of the conditions, even a small risk merits significant study before approval.

Some Study Results

In the early clinical trials, phakic IOLs were being studied equally for both myopia and hyperopia. It was concluded that phakic IOLs should only be placed in the posterior chamber, behind the iris. These early studies confirmed that risks associated with phakic IOLs were small, but also showed that the results were not highly predictable.

However, a recent Italian study of 59 eyes with posterior chamber placement of phakic IOLs showed significant results. The study looked at the patients’ results at several points up to ten years after implantation. It showed that people received the phakic IOLs achieved, on average, a spherical equivalent of +0.07 diopters, essentially 20/20, though one eye did lose one line of best corrected visual acuity. Visual acuity was stable over the ten-year period. Endothelial loss was slight, and did not increase. Intraocular pressure increased by about 5.3%, and there was one incident of closed angle glaucoma.

Overall, though, this more recent study suggests that the path should be clear for approval of phakic IOLs.

Market Concerns

The main barrier to approval of phakic IOLs for hyperopia is likely market-based. In addition to potentially increasing risks, the narrow anterior chamber of hyperopes makes implantation of the IOLs more difficult for surgeons. This makes them less popular among surgeons. With other treatment options like LASIK and PRK available, surgeons do not seem to be crowing for phakic IOLs for hyperopia treatment. With no extant market, it seems unlikely that companies will be making the big push for approval of phakic IOLs for hyperopia any time soon.

If you want to learn more about phakic IOLs or other types of refractive eye surgery, please contact a local eye doctor today.

The Eye Knows Better Than the Brain What It Has Seen

As the US Supreme Court is hearing arguments that eyewitness testimony is not a reliable category of evidence, researchers are proving that eye witness testimony might actually be the answer.

Police and lawyers have long struggled with the reliability of eyewitness testimony. In 12 Angry Men, the eyewitness testimony that may have served to convict a young man of murder is famously dismissed because of the eyewitness’ myopia, but even without refractive error, eyewitness testimony is unreliable. According to recently released research, about 75% of DNA exonerations come in cases where an eyewitness misidentified the perpetrator.

This is due, in part, to the pliability of memory, which can be altered by an act as simple as retelling what happened. By the time a witness is asked to identify a perpetrator from a line-up, he or she may have been asked to retell the events several times, and each time the memory is accessed, it is also resculpted, and the actual visual memory is lost and replaced more or less with a set of descriptors.

However, it turns out the eyes themselves also have a memory, distinct from the one in the brain, that might be a better way to make eyewitness identifications. According to research to be published in Psychological Science, eye movements more accurately identified a remembered face than conscious identification.

The researchers gave students a set of 36 faces to study. These faces were also subtly morphed to create slightly different faces that were not seen by the students. Then students were shown 36 3-face displays and identify a face they had seen, if there was one. If there was not a face they had seen before in the display, they were to pick any face and verbally say whether the face they were looking for was there or not. Eye tracking was used to look at the movement of their eyes as they were making their identifications.

The research showed that eye movements disproportionally moved to the previously seen face even before an identification was made. However, this memory is not immune to rewriting. Once the person had identified a face as having been seen before, the eyes kept moving to the “known” face as if it had been seen before, whether it had or not. In the words of researchers, “pre-response viewing seems to reflect actual experience, and post-response viewing seems to reflect the decision making process,” which leads the eye to “endorse” the face the brain has decided is the right one.

This research is in its early stages, but perhaps it will in the future allow for more reliable eyewitness reports and fewer wrongful convictions.

Also helpful in being a reliable eyewitness is having your refractive error corrected. To learn more about LASIK, please talk to a local ophthalmologist today.

Study Reveals the Effect of Long-Term Space Travel on the Eyes

Results from a NASA study show that long-term spaceflight could have a significant impact on the eyes. The study looked at seven astronauts who had spent six continuous months or more in space, on the international space station. All the astronauts were about age 50.

The astronauts all reported some degree of visual symptoms, including blurriness, which was reported by all subjects. The visual symptoms typically began around six weeks into the mission. An in-depth examination of the astronauts’ eyes showed that all had one or more of the following symptoms:

  • Flattening of the back of the eyeball (five subjects)
  • Folds in the vascular tissue (choroid) behind the retina (five subjects)
  • Excess fluid around and presumed swelling of the optic nerve (five subjects)

Researchers speculate that the changes might have been caused by increased intracranial pressure, abnormal flow of spinal fluid around the optic nerve, changes in blood flow, low intraocular pressure, or a combination of factors. In orbit, astronauts experience what is known as microgravity, which can change the distribution and flow of fluids in the body.

Most of the astronauts reported that visual symptoms went away about 6 weeks after returning to earth, while others report symptoms lasting months or years.

Overall, visual changes are seen in about 23% of astronauts on short missions and 48% of astronauts on longer missions. However, it is unknown which changes resulted in visual changes. Although choroidal folds can sometimes be associated with visual symptoms, it is more likely that visual changes were caused by flattening of the eye, which could result in hyperopia, since the lens might be focusing light behind the retina. Researchers also propose that the astronauts may be experiencing presbyopia, which would be more common in astronauts now that their average age has increased.

Visual changes associated with space travel have been speculated since the earliest days. “space anticipation glasses” for improved visual acuity were made for early astronauts. John Glenn and others had them in their space capsule.

These findings are significant for longer trips to Mars or other planets that are being planned for this century. Perhaps these findings will encourage the use of faster continuous-acceleration voyages rather than lower-energy but cheaper “coasting” missions.

If your vision is not as clear as it used to be, you should visit a local ophthalmologist for a comprehensive vision exam.

Increased Astigmatism Risk for Hispanics, African-Americans, and Children of Smokers

Astigmatism is when the cornea is not circular. Instead, it is flattened, more like a section of a football than a section of a soccer ball. Astigmatism is a refractive error that is associated with difficulty seeing at all distances. Astigmatism can also be more difficult to correct with LASIK than other types of refractive errors. Now a new study has shown more light on the risk factors associated with this type of refractive error.

According to results of the Multiethnic Pediatric Eye Disease Study and the Baltimore Eye Disease Study, several factors are associated with an increased risk of astigmatism among preschool-aged children. There was a total of 9970 children involved in the study from Los Angeles, California and Baltimore, Maryland counties. The researchers were looking for connections among clinical, behavioral, and demographic factors with astigmatism.

Researchers found that if you had either myopia or hyperopia, you were at an increased risk of having astigmatism. Hispanic and African-American children were more likely to have astigmatism than non-Hispanic white children. Hispanic children were about 140% more likely to have astigmatism, while African-American children were about 50% more likely to have astigmatism. Researchers also found that a mother who smokes increased the risk her child would have astigmatism by about 50%.

These results largely confirm previous results about astigmatism, but the connection with maternal smoking is relatively new, and important.

Astigmatism is harder to correct than either myopia or hyperopia using laser vision correction techniques such as LASIK. In the past, many patients were turned away because it was impossible to correct astigmatism. With the introduction of wavefront-guided LASIK, however, the treatment of astigmatism has become more commonplace, leading. Even irregular and mixed astigmatism can be corrected with LASIK.

If you or your child is having vision difficulties, please contact a local eye doctor to learn about the best treatment options for your vision.

Time Spent Outdoors may Prevent Myopia in Children

Children who spend more time in natural light and looking at distant objects may be less likely to develop myopia, according to recent studies.

Myopia is nearsightedness, a condition in which the eyeball is elongated from front to back. Myopic eyes focus light in front of the retina, causing distant objects to appear blurry.

The conclusion about natural light exposure came from a review of several studies from the University of Cambridge. For the 10,400 children and adolescents in the study, each additional hour spent outside decreased the risk of myopia by 2 percent, according to Anthony Khawaja, MD. Dr. Khawaja presented these results at the American Academy of Ophthalmology’s annual meeting in Florida.

Additionally, nearsighted children in the study spent 3.7 fewer hours per week outside, compared to children with normal or farsighted vision.

The reasons behind the findings are not clear. Dr. Khawaja said that further studies are needed before any well-founded recommendations can be made. Possible explanations of the findings include:

  • Children who play outside focus on distant objects more frequently
  • Children who play outside look at objects up-close less frequently
  • Natural ultraviolet light exposure prevents myopia
  • Increased physical activity prevents myopia

Among ophthalmologists, it has traditionally been somewhat controversial to suggest prevention of myopia in children. Many nearsighted children have parents with the same vision disorder, suggesting that myopia is in some cases genetic. Hereditary causes of nearsightedness cannot be changed, but this new study seems to suggest that the environmental causes of myopia can be prevented.

Progressive myopia causes a child’s vision to change until it stabilizes around age 20. The conclusions from these studies provide some insight into how environmental factors can be manipulated to decrease the risk of nearsightedness or slow the progression of the vision disorder.

Judging from the current prevalence of myopia (about 41 percent of Americans are nearsighted, according to the National Eye Institute), it seems that certain modern behaviors have put us at risk for nearsightedness. Nearsightedness is much more common today than in decades past, and this could be because of the rampant need to view objects – such as computer screens – up close in today’s educational and business spheres. Further research is needed to determine if balancing today’s up-close tasks with outdoors activity can prevent or decrease myopia progression.

To find out more about treating myopia in children, please contact an experienced ophthalmologist in your area today.

Eye Care for Children

While most children are born with healthy eyes and good vision, it is quite common for children to develop refractive errors in their vision early in life. It is important to address these vision issues as soon as they arise since they can impact many areas of your child’s life, including performance in school, sports, and many other activities.

The most common vision issues affecting children include:

These refractive errors can easily be diagnosed with a routine eye exam, and your child’s vision can be corrected with glasses or contact lenses.

If your child holds reading materials up close or very far away, it may be a sign of vision issues. Similarly, if your child squints at far away objects such as the TV or a blackboard at school, you should have their vision checked.

Unfortunately, most children are not suitable candidates for LASIK. You must wait to undergo LASIK until after your vision has stabilized and for most children, this will not happen until after the age of 18. As a general rule, you must wait until your child’s prescription has been constant for at least one year before considering LASIK.

Please contact eyes.com today to find an experienced eye doctor in your area.