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(EMAILWIRE.COM, June 17, 2009 ) Many patients who are preparing to undergo laser eye surgery worry about what their reading vision will be like after the procedure. Dr. John Suson of Suson Eye Specialists, in Wauwatosa, WI, is an expert in the field of laser eye surgery, and recently offered some advice to soon-to-be patients who may harbor this concern.
"The normal youthful eye has the ability to focus on objects at many different distances. The eye is like a camera which can be made to focus on something at 3 ft or 20 ft and still take a good photographic image. We call this refocusing ability 'accommodation' and we all have the ability to unconsciously and automatically do it from the time we are born," Dr. Suson explained.
The lens of the eye is very flexible and able to change shape which allows it to "autofocus" much the same as your hand-held camera. But as we get older, the eye begins to lose this ability. The lens stiffens and hardens so that it can no longer accommodate. This process is called presbyopia which means literally "old" eyes. It usually begins to occur in the early 40s and leads to the use of reading glasses or bifocals in order to see well up close.
Many people who have cataract or refractive surgery are hoping to be able to "throw away" their glasses forever. But the onset of presbyopia makes that only partially true. A patient that undergoes Lasik surgery after a certain age will still have some dependence on glasses for reading. There is no way to laser a "bifocal" onto the cornea during Lasik. However, there are ways to minimize the use of glasses for distance and near, but they require some consideration and choice on the part of the patient.
"One option is choosing to use reading glasses after Lasik surgery which allows us to concentrate on optimizing their distance vision with the Lasik. This strategy tends to work best for individuals who engage almost entirely in activities or sports that require excellent distance vision only. I actually find this to be rare, because normal daily life does involve a certain amount of close up vision, e.g. reading your watch, seeing a computer, or reading a menu," Dr. Suson explained.
The most common strategy for dealing with close vision but avoiding reading glasses is called "monovision." Monovision involves leaving one eye (usually the non-dominant eye) slightly nearsighted. The brain has the capability of learning to use one eye predominantly for distance and the other for up close. However, the greater the difference between the two eyes, the more difficult this becomes.
In order to read a book for extended periods of time, most people over age 45 would have to be left with about -1.50 to -2.50 of nearsightedness in their non-dominant eye. This level of monovision concerns me for a couple of reasons. The distance vision is usually significantly compromised and many people will begin to reject it because of a noticeable disparity between the two eyes. As the monovision increases, it just becomes too great a blur for the brain to filter out. In some people, high levels of monovision will also cause a sense of loss of depth perception. In addition, there are some theoretical concerns with the more advanced laser treatments that intentionally leaving significant monovision may compromise the higher order wavefront laser treatments in unpredictable ways. The wavefront laser treatments are calculated based on full treatments and it is unclear what the effect of doing half of a wavefront treatment has on higher order optical aberrations.
Instead, a strategy of "mini-monovision" where there is no more than -1.00 of nearsightedness in the up close eye is advisable. Ideal would be somewhere around -0.6 to -0.75. This distance is a normal distance for working on a computer which is where much of close work is done in the modern era. Generally this mini-monovision gives good vision for 90% of our daily tasks, e.g. reading your watch, cell phone, iphone, computer, menus etc. The goal at this stage is not to eliminate, but to minimize the use of glasses in the most situations that a person is likely to face in the normal course of their daily activity.
Monovision can also be used for patients that have had cataract surgery. However, lately developments in lens implant technology have offered another strategy. Standard lens implants are solid and stiff so they cannot change focus. Newer lens technologies are designed to be multifocal or are able to change shape to refocus. At this stage, they do not restore your accommodation to that of a 20 year old, but they can give back a fair amount of reading ability while maintaining good distance vision. There are plusses and minuses to these lenses as well, including some people that don't tolerate multifocal lenses and cost issues. Nonetheless, these new lens designs represent a great innovation and expansion of vision improvement surgery that was never possible before.
For more information about lasik eye surgery - in addition to scores of other eye-related procedures, such as cataract surgery - visit Dr. John Suson's blog, at http://www.supereyes.com/blog/
To book a consultation with Dr. Suson, or to learn more about Suson Eye Specialists, visit http://www.supereyes.com/
Suson Eye Specialists
Dr. John Suson
414-778-2020
doctorjohnsuson@gmail.com 
Source: EmailWire.com
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