Encore Vision Center

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Corneal Refractive Therapy (CRT)

"Experience freedom from the hassles of glasses and daytime contacts, without surgery."

Corneal Refractive Therapy ("CRT") is a non-surgical treatment that corrects myopia (nearsightedness) and astigmatism (out of round corneal surface) using the overnight wear of treatment lenses. The lenses gently reshape your corneas while asleep. Upon waking, and removing the lenses, you will experience clear and natural distance vision, without glasses or contact lenses throughout the day.

In a myopic (nearsighted) eye, light from a far away object is focused in front of the retina, resulting in blur. In essence, the eye is too strong for itself. Traditional spectacle lenses change the direction of light before it enters the eye, allowing for the image to be focus on the retina for clear vision.

Corneal refractive therapy works by altering the eye's power, allowing light to be precisely focused on the retina without the use of standard lens corrections. Unlike refractive surgery (LASIK), CRT is temporary, as continual use of nighttime treatment lenses is necessary to maintain its effect. We have found CRT to be an exciting new option for individuals seeking the freedom from the daytime use of eyeglasses or contact lenses. It is an especially attractive option for those that are either apprehensive about or not a candidate for refractive surgery.

Beyond a comprehensive eye examination, the following outlines the basic steps involved in the CRT process:
CRT Lens Design and Initial Fitting

A corneal topography will be performed to determine the shape of your cornea and assist in the selection of an initial diagnostic CRT lens. If necessary, additional diagnostic lenses will be tried until we obtain the ideal corneal-treatment lens fitting relationship. It is believed that the CRT effect occurs in the corneal epithelium, which is the top layer of the cornea. The treatment lens is specifically designed to alter the shape of this tissue. As illustrated in this cross section view to the right, the treatment lens is flatter than the cornea at its center and takes a plateau shape towards its periphery.

Lenses will either dispensed from our in-house inventory or ordered from the manufacturer and you will be scheduled for a progress evaluation following the first night of treatment lens wear.


  • CRT Lens Wear
    While wearing the CRT lens, the surface differences, between the lens and the cornea, forces the cornea (epithelium) to take on a new shape. Research is underway to determine just how the new corneal shape is created. It is believed that with lens induced pressures the epithelium either migrates from the corneal center or that the epithelium becomes compressed. In either case, the corneal tissue begins to take on the shape of the treatment lens back surface, which is designed to correct for myopia and astigmatism.



  • CRT Lens Removal
    Following overnight wear, the CRT lens is removed revealing a new corneal surface shape. It has been our experience that the first night of wear will correct approximately 50 to 60 % of the treatment goal. You should notice improved vision, however, the effect will fade quickly. Then, with every successive night of wear, the effect will become greater and will last longer. We expect that it will take between 7 to 14 days of treatment to obtain useful vision throughout your day. We have found that age and the degree of the pre-treatment refractive error are the primary factors controlling how quickly the treatment become effective.



  • CRT Long-term Treatment Effect
    We will closely monitor your progress and make lens design changes when necessary. Our goal is to establish clear and natural vision throughout your day. While traditional glasses and contact lenses offer vision correction options, they also induce distortions, reflections and blur from contaminated lens surfaces. CRT offers a much more natural vision as no lens is being worn during your awake, viewing hours. You will no longer be distracted from glare caused by dirty, scratched eyeglass lenses or variable vision caused by dry, dirty contact lenses. In addition, unlike refractive surgery, the effect is temporary and can be adjusted to reflect changes in your eyesight.


    Contact us to learn more about Corneal Refractive Therapy and determine if CRT is an option for you.
    Paragon CRT® Corneal Refractive Therapy



    Imagine the freedom of ... LASIK

    The freedom of being able to see without glasses or contact lenses. Imagine swimming, golfing, biking, skiing, dancing all without glasses slipping down your nose or your contact lenses drying out and blurring. Imagine the freedom of natural vision without the hassles of glasses or contact lenses. LASIK offers this freedom.

    We understand. While we provide the latest and most fashionable optical and contact lens technologies, we understand that your world could be better without these products. We actively offer LASIK refractive surgery to our patients. We provide an independent resource for LASIK information, free consultations and pre-operative evaluations to help determine LASIK suitability, referrals to a surgeon selected specifically for you, and post-operative care, all in a convenient, local location.

    We also understand that LASIK is not for everyone. Some people are not a candidate for LASIK or are uncomfortable with a permanent surgical correct. For those people we continue to offer the latest advances in glasses, contact lenses, and other non-surgical options for visual correction.


  • How does LASIK work?
    To best understand LASIK first consider how standard corrective lenses improve vision. As seen in Figure 1, the eye is too strong (myopia or nearsightedness) and is focusing light in front of the retina, creating a blurred image. Standard vision correcting options (Figure 2) (glasses, contact lenses) alter the direction of the light, allowing for the eye's natural focusing power to direct that light to the retinal surface and provide clear vision.


    As shown on Figure 3 and 4, LASIK (as well as PRK, RK) works by surgically reshaping the corneal. This permanently alters the eye's focusing power, which then redirects and focuses light on the retina.

    Contemporary lasers use advances in laser beam size and eye-tracking devices to correct an ever-expanding range of myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. The most advanced technologies utilize a laser beam smaller than the width of a human hair (about 1 mm in width). This allows corneal tissue to be removed in small, gradual increments, resulting in a smooth reshaping and more acute vision.

    Eye tracking is also vitally important for accurate LASIK results. Normally, eyes are continually moving about a hundred times a second. It is virtually impossible to keep the eyes still, even when making a conscious effort. Yet, it is critical that the laser beam be applied to the exact spot. The latest generation lasers follow eye movements at 4,000 times per second and provide continuous feedback. The end result is a higher degree of accuracy, more precise vision and, ultimately, greater patient satisfaction.

    Look to Encore Vision Centers for your laser vision correction needs.

    We can help determine whether LASIK is your most appropriate refractive therapy choice and what surgeon is best suited for your needs. We can also be your source for convenient post-operative care.

    Candidacy factors to be considered will include your refractive error (prescription), overall ocular health, corneal shape and thickness, pupil size, and contact lens wearing history. Beyond a comprehensive eye examination, a variety of sophisticated instruments including a corneal topographer, pachymeter and pupillometer should ultimately be utilized to ensure accurate assessment of the above factors. Based on the results compiled from this process, our doctors and your surgeon will customize your LASIK procedure for your individual needs.

    Contact lens wear can play important role in evaluating LASIK candidacy. Contacts alter the shape of your cornea, your corneal thickness, and the nature of your tear film. To best assess your candidacy, you will be asked to discontinue contact lens wear for a period of time prior to the screening / measurement process. The length of time is variable depending on the type of contact (hard, soft or toric) and the frequency /duration of use. Our staff will provide some guidelines to contact lens use when you schedule your appointment.

    Post-operative care can also be managed by Encore Vision to ensure your very best results. Following the LASIK procedure, healing begins virtually overnight. It is very important to rest immediately after surgery and to keep your eyes closed as much as possible. A follow-up appointment is scheduled with your surgeon 1 day post-operatively. Following your one-day post-operative visit, normal activities can usually be resumed. Your surgeon will give direction if there is an exception.

    Expect your vision to fluctuate slightly for the first few days post-operatively, with healing lasting between 3-6 months. Should you choose the remaining follow-up care can be provided by Encore Vision Centers. Typically you would be evaluated 1 week, 1 month, 3 months, and 6 months following your procedure. Please note that other visits may be necessary based on your individual response. All follow up visits, related to LASIK, within the 6 months following your procedure should be included in the total fee.

    Please contact us to determine if you are a candidate for LASIK.


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