Monthly Archives: February 2010

Calgary Epi-LASIK, LASIK, PRK, Intra-LASIK: What is Custom Wavefront Laser Vision Correction?

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Once you decide you are interested in having laser vision correction surgery there are several things to consider. Which procedure is best for you? Which surgeon to choose? How much will it cost? What type of laser will be used?

Laser vision correction can be done by making a corneal flap and placing the laser treatment under the flap; the flap can be made by a mechanical microkeratome for LASIK or with the femtosecond laser with Intra-LASIK. Many surgeons are favoring surface no-flap treatments due to the lower risk and equally good long term results; no flap treatments include PRK and Epi-LASIK.

For either no-flap or flap treatments the application of the laser can be a standard treatment or a customized wavefront treatment. The standard treatment will treat simple sphere (nearsighted or farsighted) corrections as well as astigmatism corrections. For a true custom wavefront treatment measurements are made using a wavefront analyzer before surgery. The wavefront analyzer uses infrared light which is projected into the eye; the light is measured as it exits the eye and analyzed to provide an aberrometry map. The aberrometry map contains information about the simple sphere and astigmatism corrections along with more complex higher order aberrations. Each individual will have a unique set of higher order aberrations. The Wavescan aberrometer uses approximately 240 data points to create a unique aberrometry map that can be used for a truly customized wavefront treatment by the Visx S4 IR excimer laser.

The Visx laser is the most widely used excimer laser in North America. For customized wavefront treatments the wavescan aberrometry map data is loaded into the Visx S4 IR excimer laser for each unique eye to be treated. The wavescan aberrometry map also contains information regarding iris landmarks (the iris is the colored part of the eye surrounding the pupil). This iris information is used during treatment to recognize the unique eye to be treated and to adjust the treatment for cyclorotation and iris centration. Cyclorotation is the rotation of the eye which can occur between sitting upright and laying down. For some people this rotation may be greater than 10 degrees. The pupil may also shift slightly in response to lighting conditions. The iris recognition feature available on the Visx S4 IR excimer laser system allows for the precise application of the laser treatment for optimal results.

While many people have had satisfactory results with standard laser treatments, there is evidence to show that true custom wavefront treatments offer better results. An analogy that is often used is that of an off the rack suit compared to a tailor-made suit. Custom wavefront laser vision correction is tailored to your individual eye.

Choosing to have laser vision correction is a big decision. Considering all the factors involved including laser type and standard versus wavefront corrections will help you make the choice that is best for you.

More information is available in Dr. Anderson Penno’s latest book “Laser Vision Correction: What You Need to Know” which is available here.

To book a complimentary assessment with Dr. Anderson Penno, contact Western Laser Eye Associates today.

Epi-LASIK, PRK, LASIK & Epi-LASIK: Laser Vision Correction When You’re Over Forty

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For those over the age of forty who are considering laser vision correction, it is important to understand the effects of age on the ability to focus up close.

This age related loss of focus ability is called presbyopia. For people with good uncorrected distance vision and for those who have a full contact lens correction for distance, presbyopia means that at some point after the age of forty you will begin to need reading glasses (or reading glasses over your contacts) in order to read up close. As this age related process continues you will begin to need glasses for computer work and other intermediate work. People who wear glasses full time will need a progressive lens or a bifocal in order to read with their glasses on. Before progressive (lineless bifocal) lenses were available you would likely get a bifocal sometime in your forties, and then a trifocal to include the mid-range correction in your fifties. People with mild nearsightedness may simply take their glasses off to read rather than getting a progressive or bifocal eyeglass.

Those who wear contacts for distance with reading glasses over their contacts will eliminate the need for their distance contact lenses but will still need reading glasses after laser eye surgery if both eyes are corrected fully for distance. For people who wear bifocal or progressive lenses, laser vision correction will eliminate just the top distance correction if a distance target is chosen. Reading glasses will still be needed following surgery, and if you are in your fifties then a mid-range correction might be required as well. For the mildly nearsighted people who are over the age of forty, they may be trading their distance glasses for readers with a full laser vision correction. For this group, anything the ordinarily do with glasses off will require readers. An example is someone who does desk work all day with their glasses off and then puts their glasses on to drive home; this person will wear readers and possibly computer glasses all day at work and then take them off to drive home. It is important to understand the effects of presbyopia in order to make sure you will be satisfied with the outcome of surgery.

The only alternative to readers for those who undergo laser vision correction and are over the age of forty is to consider monovision. Monovision is when one eye is corrected fully for distance and the other is left mildly nearsighted for close work. This arrangement may work well for some people, but it is important to simulate monovision with contact lenses or with a trial-frame in your eye doctor’s office before considering it for a permanent laser vision correction. For a mildly nearsighted person, monovision may mean that a correction is done only in one eye and the other is left untouched. If possible the trial should include both ways – right eye for distance and left for close and then left eye for distance and right for close. Your optometrist can assist you in doing a monovision trial with contact lenses.

If you can adjust to monovision and are over forty, this option will give you the widest range of functional vision without having to put readers on and off. Monovision may not completely eliminate the need for glasses. Some people with monovision might prefer to wear glasses for night driving or to wear readers for detailed close tasks like sewing. Monovision is a compromise. Your best vision will be obtained with both eyes corrected, which is why some people with monovision will wear glasses for specific tasks. People who spend a large amount of time doing hobbies like tennis or golf or who depend on distance vision for their jobs like professional drivers may not be good candidates for monovision. In general, monovision is not recommended for younger people since the benefit of monovision will not be present until sometime after the age of forty.

Whether to do a full correction for distance or to do monovision with any of the laser vision correction techniques is a personal choice. It is important if you are over the age of forty to understand the choice you are making so you are not disappointed by having to wear reading glasses or computer glasses after surgery.

More information on monovision and other laser vision correction options is available in Dr. Anderson Penno’s book “Laser Vision Correction: What You Need To Know”. It is available at Amazon here.

To book your complimentary laser vision assessment, contact Western Laser Eye Associates today.

New Book About LASIK, PRK, Epi-LASIK, and Intra-LASIK

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Dr. Anderson Penno is pleased to announce that her latest book “Laser Vision Correction: What You Need to Know” is now available on

This book is an excellent resource for anyone considering vision correction surgery. You can find out more and buy the book here.

“Laser Vision Correction: What You Need to Know” is also available at and is coming soon to Kindle.

To book your complimentary assessment with Dr. Anderson Penno, contact Western Laser Eye Associates today.