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At Future Vision Laser Center, our passion takes LASIK and other refractive procedures to a higher level. We believe that providing our patients with the most extensive pre-operative evaluation is critical in determining the success of the procedure. The following is a description of the pre-operative evaluation you will have at Future Vision Laser Center.
We often start with a device that looks at the light reflected out of your eye while staring off down a rod to judge how far in front of you the light rays will focus. It will give a starting point for determining the prescription needed to clear your vision. It also determines the curvature of your eye over the central part of your cornea. It can also measure your pupil in moderate to dim light.
The GDx is a laser scanning ophthalmoscope that measures the thickness of the retinal nerve fiber layer for possible glaucoma. Through our research we have identified several people who either have or are at risk for glaucoma, a serious sight-threatening disease. The rational for using it is explained above.
 A digital camera system is used to evaluate and map the front (anterior surface), back (posterior surface), by modeling thousands of thickness points along the entire cornea. It does this with a slit beam of light projected in two directions and measured with video cameras. Triangulation is then used to derive the thickness. A computer aided design program then models the front and back shape of your cornea. The anterior chamber depth may be an independent risk factor for glare and halos in lasers that treat with small zones. The curvatures on your eye will be depicted on a colored elevation and curve maps. You can also find the thinnest point on your cornea, which does not always correspond with the center. Posterior curvature can only be seen with this device and is very important in assessing your treatment. It really is an indispensable tool in refractive surgery. Not all LASIK Laser Centers are using this crucial technology. Serious irregularities in the cornea that would go undetected without the Orbscan have made this the gold standard to our work. Visit the Bausch & Lomb Orbscan site.
We have submitted data to the FDA for linking the data of the Orbscan to a second device called an aberometer, similar to the autorefractor only it maps your pupil exposed cornea. The data is analyzed and reported to the laser, which then treats your eye. This is called Xyoptics and will be available the early part of next year. It will be important for eyes that are unusual in shape usually not able to make 20/20 on the eye chart. It may work best as a refinement procedure to fine tune a primary result. This wavefront and Orbscan guided system has been performing well in Canada and in Europe and we will be one of the first here in the US to offer it.
An infrared camera is used to determine the maximum pupil size in complete darkness. This is called scotoptic measurement and allows us to standardize your pupil size for treatment. Measurement in dim light or mesoptic pupil size is not done with a light meter and is more variable. You do not get glare and halo in total darkness as your pupil would react to the light causing the halo and would be smaller. Furthermore, the measured pupil size is about 15% larger than your actual size because of the effect of your curved cornea. It is our contentions that if we can treat your scotoptic pupil size safely we are going to give you the best optics at night. The infrared light source has been found to be the most accurate, with results of 1 to 1.5mm larger measurements than previous tests with the cobalt blue light. These previous tests result in an unacceptable margin of error in this critical component of the evaluation. We will video your pupil as well looking for activity. Try to look across the room as looking at the technician will shrink your pupil. Knowing the maximum pupil size is necessary in order to minimize night glare or halos after LASIK. The Bausch and Lomb laser treats with the largest zones of any laser and claims the best night vision as a result. Remember that the larger the treatment the more tissue is required to treat. In rare cases usually large corrections with thin cornea and 8mm pupil size the laser procedure may give decreased night vision and we would discuss this with you. View Measurement
We believe that it is very important to do a tear film analysis as the overall quality of the tear can affect your success. If you have dry eyes or other tear film abnormalities, we can institute care before or after your procedure to maximize your outcome. After your eyes are numbed with drops, sterile strips are attached to the lower lids for 3 minutes to analyze tear film stability. The tear film is observed while you stare and the time that the shear force breaks the film is noted. Refer to the above section on the importance of tear film.
Your vision will be checked with and without correction. An accurate measurement of your visual acuity is the single most important factor before you have a permanent alteration in your visual system. If you are a contact lens wearer, we are especially concerned that your cornea is stable. This can be one of the most common causes of problems with the LASIK procedure. We will measure your visual acuity as well as look at your cornea with the Orbscan several times, including the day of surgery, if necessary. NOTE: If you are a contact lens wearer, we will require you to discontinue their use up to 4 weeks prior to the evaluation, depending on the type you wear.
Soft daily wear lenses: remove 5 days prior
Extended & Soft toric lenses: remove 3 weeks prior
RGP (ridged gas permeable) lenses: remove at least 4 weeks prior.
If you have worn RGP for many years, 4 weeks may not be enough time. In rare cases, it has taken up to 3 months for the cornea to stabilize. The patient can opt for daily wear lenses during the initial period and then wear glasses for the five days before the evaluation.
Before dilating drops are instilled, you will be examined for your most current prescription using a computer generated and standardized illuminated eye chart
This is known as the red and green test, which shows the accuracy of your current prescription. The green light falls in front of the retina and the red light behind. A balance of these two lights is helpful in determining your optimal correction.
Eye pressure is measured via an applanation type tonometry (Goldmann), which is more accurate than the "puff" tonometry. Your eye pressure reading will be changed by LASIK, therefore, we think that this pre-LASIK measurement is critical to your future eye health.
This test will determine which of your eyes is dominant, similar to handedness. If you are over 40 years of age, you may want to consider under-treatment of your non-dominant eye. This mild difference in your vision can leave you with a visual system that can still see near and mid ranges without reading glasses. We will discuss this with you and show you what this would look like. If you are interested a trial of a contact lens can be helpful in making this important decision and we will provide a pair at a nominal cost. This is an excellent way to determine if blended or monovision could work for you.
Using drops to dilate the eye, a cycloplegic (class of drugs used to artificially dilate the pupil and relax the muscles aiding your near or far vision) refraction is done to find out if there are any refractive changes after dilation. Your treatment may be modified to account for these changes, should they occur.
This is an evaluation of the posterior segment of the eye (vitreous and retina) via binocular indirect ophthalmoscope. We use this exam to rule out possible retinal diseases. In general, nearsighted people have more risk of some retinal problems. These are best treated prior to LASIK to reduce the risk of retinal detachment in the future. LASIK itself, as shown in numerous studies, does not increase the risk of retinal detachment. We will also evaluate the lens to determine if you have developed cataract, which might alter your treatment plan. We would normally treat cataract first and if you had residual refraction after the implant then use the laser. When the evaluation is finished, your eyes will be dilated and this could last up to 30 hours. This is why we ask you to bring a good pair of sunglasses if you have them. If you are a contact lens wearer or don't have a pair of prescription sunglasses, we will provide you with a pair of wrap-around sunglasses that will fit over your glasses. The tests listed above will be repeated as necessary to achieve consistent measurements that will ultimately be programmed into the computer. You will watch an informative video and take a test. We will take the time to answer questions and you can meet Dr. Foulkes to discuss his treatment plan and his assessment of your probability of success. You will meet with our refractive coordinator who can deal with scheduling and any financial issues. If you choose to book you will be given a folder with all of your necessary information (which is also available here) for pre and post- operative instructions. We will give you a prescription for antibiotics to start 3 days prior to surgery. Remember this builds up a level in your cornea and reduces your risk of infection. We will call you the day before surgery to cover any issues and you will have Dr Foulkes home and cell numbers.
The follow-up schedule after LASIK surgery is 1 day, 1 week, 6 week and 1 year.
We will be checking the following:
Visual acuity.
Refraction.
Intra-ocular pressure.
Contrast Sensitivity.
Anterior segment evaluation:
To evaluate the integrity of the flap made on the cornea during the LASIK procedure and dry eye
symptoms. We have a low threshold for the use of punctal plugs or colagen implants to help normalize your tear film early on. This can mean an additional nominal cost that can often be billed to your insurance.
Orbscan and wave front
GDx - 3 months, and 1 year.
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