Monthly Archives: June 2015

Happy Birthday PRK!

By | Laser Eye Surgery, Laser vision correction, LASIK, PRK, Refractive Surgery, Uncategorized | No Comments

Photorefractive keratectomy (PRK) is the original laser vision correction surgery that was first performed in the US in the 1980’s and on June 12, 1990 at the Gimbel Eye Centre in Calgary Alberta Canada.  In the 25 years that followed PRK first gained in popularity over radial keratotomy (RK) in which incisions were made in the cornea to flatten the surface of the eye for treatment of nearsightedness.  PRK has the advantage of precision laser modification of the corneal curvature using the excimer laser.  The excimer laser was originally intended for industry and manufacturing but when a curious researchedr took some leftover Thanksgiving turkey back to to lab laser vision correction was born.

PRK quickly replaced RK as a more stable and precise way to eliminate the need for glasses or contact lenses.  As the search for improvements continued into the 1990’s the older technology of cutting a corneal flap was combined with the excimer laser reshaping in a treatment that was first called “FLAP & ZAP” and later laser in situ keratomileusis (LASIK).  LASIK quickly overtook PRK as the most popular laser vision correction method into the early years of this century due to the faster healing the flap allows.  Throughout this time PRK remained a trusted method and was considered safer than LASIK for thinner corneas and for athletes and people with occupations that might risk eye injury due to the risk of a LASIK flap shirt.

As the early 2000’s progressed a new and difficult to treat complication became recognized – corneal ectasia. Ectasia after LASIK is uncommon but can result in an unstable corneal surface that is analgous to a weak spot in a tire, which makes the surface of the eye bulge out and become irregular over time.  There has been a lot of debate about ectasia after LASIK, but many eye surgeons believe that PRK may be a lower risk for this specific problem due to the fact that the cornea is not disrupted as deeply as compared to LASIK.  The LASIK flap does not leave the eye but once it is cut it may no longer contribute as strongly to the corneal structure.  This weakening in addition to a number of other risk factors appears to play a role in post LASIK ectasia.  All the while PRK has continued to be offered as an option for laser vision correction in particular for people who might not qualify for LASIK.

In the past few years many surgeons around the world have moved “back to the surface” and choose not to cut corneal flaps in order to affect the smallest amount of corneal tissue needed to improve uncorrected vision.  Advances over the last quarter of a century since PRK was first done include significant advances in excimer laser technology including iris recognition, cyclotorsion adjustments, and the ability to do individually customized treatments using wavefront technology.  In addition, improved bandage contact lenses and medications have been developed to reduce post-operative discomfort and risk for haze following PRK.

PRK turns 25 this year in Canada and is still going strong!

If you have questions about laser vision correction or wish to book a complimentary evaluation with Dr. Anderson Penno, contact Western Laser Eye Associates.

Vision & Vitamins: Ginkgo Biloba, Glaucoma, and Macular Degeneration

By | Epi-lasik, Epilasik, Eye health, FDA, Food for thought, Ginkgo Biloba, glaucoma, Health Canada, Laser Eye Surgery, Laser vision correction, macular degeneration, Mayo Clinic, Ophthalmologist, Ophthalmology, Opthamologist, Optometry, Pubmed, Refractive Surgery, science, Uncategorized, Vision & Vitamins | No Comments

Vitamins and natural herbs have become more and more popular for alternative treatment as additional treatments for medical conditions.  Ginkgo Biloba has been used for centuries as a traditional treatment which may help blood flow to the brain and aid in treatment of dementia or Alzheimer’s disease.  It might help treat leg pain that results from blood vessel disease, and there is some suggestion that ginkgo biloba might also help PMS symptoms, depression, multiple sclerosis, and ADHD.  Ginkgo Biloba is extracted from the leaves of the Ginkgo Biloba tree.  As far as vision and eye health are concerned, it is possible that Gingko Biloba might be helpful to eye health but as with many natural products the scientific studies show some favorable and some unfavorable results.

There are some scientific studies that have been reported in the peer reviewed literature which is a data base of articles that have been reviewed by scientists with expertise in the particular field of study before the article is allowed to be published.  Peer review helps to make sure that studies are done in a way that will provide strong statistical evidence for or against a specific area of study.  The most powerful studies are randomized and double-blinded which means the researcher and the subject who is taking the supplement do not know if it is the actual supplement or a placebo being taken.  The “placebo” effect has been well studied and up to 30% of people taking a fake pill who are told it will have beneficial effects will report that it helps whether or not there is any measurable effects.  By double-blinding and using large and randomized numbers of subjects the results will show with more confidence that a particular supplement is helpful or not for a specific condition.  Because there are a lot of different conditions that are being studied, so far there are only a few published peer reviewed scientific studies that have been done to find out if Ginkgo Biloba is good for your eyes.

According to the Mayo Clinic there is some scientific evidence suggesting that Ginkgo Biloba may be helpful in preventing worsening in age related macular degeneration which can lead to central vision loss, but there is little evidence to suggest it might be helpful for treatment of glaucoma.  In the peer reviewed literature there are a few studies including this 2012 study by Cybulska-Heinrich, Mozafferieh and Flammer that suggests supplementation with Ginkgo Biloba might be helpful in addition to traditional medical treatment in cases that are not responding as well as needed to these traditional treatments.  They suggest that antioxidant effects along with a variety of other effects on blood flow might be responsible for the beneficial effects of supplementation with Ginkgo Biloba.  The American Academy of Ophthalmology reported there was a single small randomized trial that showed promise for using Gingko Biloba to slow macular degeneration.

A commonly reported dose of Ginkgo Biloba is a standardized extract, standardized to 24% flavone glycosides and 6% terpene lactones starting at 40 milligrams of that extract three times daily, but there does not seem to be enough evidence in the scientific studies to prove the most effective doses for a specific condition.  Risks and side effects of Ginkgo Biloba supplements include headaches and dizziness, bleeding, and other side effects.  If you are on a blood thinner or aspirin, or are on other medications you should talk to your pharmacist and/or doctor to make sure that there won’t be dangerous interactions.  There is also some question about the quality of the products in some cases and as with all supplements it is important to be sure you are getting a high quality product.  In Canada a DIN or NPH number can be found on products that have been reviewed by Health Canada.  In the US the FDA does not require approval of supplements before the product is marketed but does collect information on adverse events.  The other thing to consider is the cost of a product like Ginkgo Biloba versus the proof that it will be helpful for your health.

Whether you already had LASIK, Intralasik, EpiLasik, PRK, wear glasses or contacts, reading glasses or no glasses at all you should be sure to get regular checks with your eye care specialist (optometrist or ophthalmologist) in order to optimize your vision for the rest of your life.  If you have questions about laser vision correction or wish to book a complimentary evaluation with Dr. Anderson Penno, contact Western Laser Eye Associates.