Customized Ablation 1 Ive Seen the Future and its CustomCornea!

This Technology Update column is the first of a series of eight articles chronicling the development of Customized Ablation or Wavefront Driven LASIK. This column was published in the June 15th issue of Ocular Surgery News following both the 1999 ASLMS (American Society for Lasers in Medicine and Surgery) and ASCRS (American Society of Cataract and Refractive Surgery) meetings.

I've Seen the Future.....and it's Custom Cornea!

Technology Update

Irving J. Arons
Spectrum Consulting

What if you could more accurately predict and successfully restore a patients vision to 20/20 with refractive surgery. What if, in some cases, you could actually achieve "Ted Williams" type vision (20/16) or better for your patients who would want that. Would you be interested in finding out more?

Since I first heard Marguerite McDonald's presentation on custom cornea at last fall's AAO meeting (1998), I've been intrigued with the idea, and have wanted to know more about how it was going to be accomplished. The idea of not only correcting vision to emmetropia (20/20), but enhancing it to 20/16 or better was exciting and this was only reinforced by the presentations given at a Bausch & Lomb press conference at the AAO, where George Waring declared 20/12 by 2012, now changed to 20/10 by 2010 in current B&L Surgical advertisements! (For more on both of these presentations, see my columns from the AAO in the January 1st issue of OSN.)

Now, after hearing a presentation given by Tim Turner, director of research at Orbtek, on the "Orbscan Corneal Topography Laser-Link System" (at the recent American Society of Lasers in Medicine and Surgery [ASLMS] meeting in Orlando), and especially after viewing a tape of a course given at the recent ASCRS meeting by Marguerite McDonald, Ronald Krueger, Ray Applegate and George Pettit on "Wavefront-Guided Customized Ablations -- Beyond Topography-Assisted Refractive Surgery", sponsored by Autonomous Technology -- now a subsidiary of Summit Technology, I am convinced that topographically-linked ablation, and especially wavefront-guided ablations, are the future of refractive surgery.

As reported last January, several companies have announced that they are in the process of combining corneal topography with their excimer laser systems to be able to perform "custom" ablations. Among those are LaserSight, working with Humphrey-Zeiss and Orbtek; VISX, working with EyeSys Premier and Orbtek, among others; B&L Surgical/Chiron with Technomed and Orbtek; Schwind with Technomed; and Aesculap-Meditec, also with the Orbtek system and possibly Technomed.

In Dr. Turner's presentation, he explained how the first-generation of topographically linked laser ablations, which depend on the capture of topographic information (corneal curvature and elevation) supplied by such placido reflection systems as Computed Anatomy and EyeSys Premier, will probably be the first out of the block, along with the Orbscan slit scanning system. The Orbscan is capable of providing additional information such as the thickness of the cornea and the condition of its rear surface, through what Orbtek calls CIPTA, or Corneal Interactive Programmed Topographic Ablation. However, by combining the Orbscan with ultrasound to determine the ocular axial length and lens thickness, a simulation of the retinal point spread function (PSF) can be determined. Point spread functions can be calculated for any surface or any sequence of surfaces. Thus a PSF can be calculated from anterior corneal data alone, but it may or may not approximate the true retina PSF, depending on the optical importance of the other internal ocular surfaces. However, this does not include local aberration-inducing variations. So, Orbtek has created a simulated next-generation measurement technique called WAVE, or Wavefront Ablation Vision Enhancement. WAVE treats patient vision rather than corneal geometry (elevation and surface curvature), by targeting idealistic post-operative surface topography with the optical PSF optimized. It calculates wavefront aberration by reverse ray tracing of all of the rays emanating from a theoretical point source of light at the fovea and back through a modeled crystalline lens and the measured cornea. Orbscan measurements are used by WAVE to fully characterize the cornea (both anterior and posterior surfaces), and other data (refraction, ultrasonic axial length and lens thickness) are used to model the crystalline lens. These additions aid in the simulation of the true retinal PSF and the ocular wave aberration. When wave aberrations are directly measurable, they can also be included in the WAVE strategy. The WAVE system is still experimental and has not yet been used on any human patients.

The major difference between what Orbtek and Autonomous Technology are attempting to do is in the measurement of aberrations. As noted above, Orbtek uses theoretical measurements and modeling to simulate an aberration pattern, while Autonomous actually measures the total aberration of the eye by shooting a laser pulse onto the retina, through the lens, and obtains an actual aberration pattern of the return waves, thus getting a more accurate pattern of what aberrations are present in the complete optical system.

Autonomous uses a proprietary wavefront sensor to capture the wavefront pattern returning from the laser-induced spot on the retina. It then converts this information into a 3D map of the aberrations to determine what changes are needed in the corneal surface to compensate for the aberrations present in the eye, and to overcome them. Autonomous has built a prototype device, called the CustomCornea Measurement Device, and, under an IRB, has placed it in an ophthalmologist's office in Florida in order to take measurements on patients under a real-life situation, beginning in April. In an in-house study of 103 eyes, including some people with 20/20 or better vision and some with known pathologies, the custom cornea maps provided by a prototype device, appeared to bear out the theory -- emmetropes, as well as those with sharper vision have less aberrations and can be distinguished from those with aberrated vision. In the near future, this information will be programmed into the LadarVision small spot scanning laser system to provide the potentially enhanced vision, possibly reaching the theoretical diffraction limits of the retina of 20/8!

Of course, all of this would not be possible without the extremely accurate tracking system available on the Autonomous laser. Since the accurate placement of the "compensating" ablation pattern is necessary, by linking the wavefront analysis device to the LadarVision tracking laser, the precise pattern of ablation correction can be obtained, centered on the visual axis, and "customcornea" achieved. The company hopes to begin CustomCornea treatments this summer, depending on regulatory approvals and, hopefully, within the next two years, this technology could become a commercial reality.

Editors note: This column was not put online by OSN. The Janury 1st column mentioned, is also not online, but was picked up by a sister publication, OCULAR SURGERY NEWS EUROPE/ASIA-PACIFIC EDITION, and published in February 1999. (Which is linked.)

Choosing The Customized Nutrition Plan

By Debra Taylor

Many people will decide that they need to start eating healthier foods through personal choice, or for medical reasons. Changing eating habits is normally the first thing that most people do and this can often work, but any drastic change needs to be managed. The most sensible thing to do is to ask the advice of someone qualified who can draw up a customized nutrition plan for you to follow.

When choosing the plan that best suits your lifestyle there are a couple of points to consider. The initial action should be to speak with your doctor and ask for their medical advice. There are often a lot of people who have allergies to food groups and other medical problems they may not be aware of, and a change in your food intake can have an adverse affect.

The majority of doctors after an initial discussion will be able to organize a plan that suits your individual requirements. A weekly or monthly plan containing some healthy menus and expert nutritional tips will be given to you. Alongside this, some gentle exercise routines may help to ensure steady progress.

A good source of reliable information for a nutritional program is the internet, and there are now businesses that offer these customized services. After you have entered your personal details and answered a few simple questions about your lifestyle, they will issue tailored nutritional advice and healthy eating menus. On some of the sites there will be chat rooms and discussion boards which will enable you to exchange advice with fellow members.

An alternative way to learn how to eat better and healthier food is to join a nutritional advice club. The clubs will generally host weekly meetings in your neighborhood where they will educate you on food and how to cook it in a healthy way. Many of the clubs will also hold informative seminars and experts will give lectures to advise you, and offer tips on healthy meals.

Sometimes it can be hard for people who have to work long hours or look after children to find time to buy and prepare healthy food. There are now online sites that will deliver prepared healthy meals to your home for a small charge. These web sites have various options to choose from and often offer help and nutritional advice as well as food management and exercise tips.

Fitness trainers are another good place to seek specialist advice on diet and to get nutritional information. After speaking with your personal trainer they will set up a custom exercise plan and in many cases give you simple ideas on what kind of foods you should eat. It is very important that you consult a qualified instructor before you embark on any harsh regimes, to ensure you are not doing too much too soon.

When you have changed your eating habits and you feel comfortable with things it is essential that you carry on the good work. Many people will go back to their old ways and this can be very detrimental to your health. Maintaining a healthy weight and lifestyle can be difficult so carrying on with your healthy eating plan is recommended.

About the Author:

If you are looking for the facts about a customized nutrition plan, pay a visit to our web pages online today. Additional details are available at http://www.herpowerlifestyle.com now.

Why Customized Fitness Plan Can Help You With Everything

By Sarah White

More and more individuals are going through each health. The world has toxic everywhere and pollution up in the air, its now time to boost up the system. So to prevent any sickness, exercising body is a decent way to go.

Which is why its easier right now to just stay at home or call up a trainer to lose fats and gain enough muscles. Customized fitness plan is a way to be healthier and much active on a regular basis. Check out the facts in here and maybe get it by the end of this article.

The word alone meant that it is solely created for users, whatever or whoever they might be. Theres options from any level to see to it that the condition is always put into priority. Its also signify that its more suited for anyone who wants to take this one in more ways that they want.

Everything that this one is being use, it has different programs that one can take which are according to what they can get use. In this regard, anyone can select through the options that they have in their midst. By that alone, its going to help out a lot of individuals out there that wants help with their weight.

And if you want to take your own work out, you can always download it with the use of your wifi and gadgets. So whether you are working, studying, or just spending a good time at home, you can just whip your phone and start doing it. By this alone, exercising for you would just be easier than saying the alphabet.

And of course, this type of work is being created by individuals who knows all the ways and turns when it comes to working out. And because of this, you are well assured that you're safe and following a very formal procedure coming from persons in this caliber. And for this, you would do well in just by having a minutes time exercise.

And when you take this one to heart, then you would be losing every inch of excess fats and muscles and tone it out well. You're going to have a much healthier self and help you out with all the demands in life. So get this, and soon you will be much happy and well assisted even with just an operation system.

Plus, they also included the right food that individuals using this need s to partner it up for their daily routine. They also have drinks in here so that everything is measured up the way meals should be taken up everyday. With that such help, its the one good thing which supports everything that needs to be done in here.

And because these make use of the system generated, anyone can monitor their progress too. From apps to charts, this one has loads of information to give out to other people. For that alone, it is much helpful and informative to anyone who would use it.

About the Author:

When you are looking for the facts about customized fitness plan, go to the web pages online here today. More details can be seen at http://www.herpowerlifestyle.com now.