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    Wavefront technology becomes important preop, postop tool

    Evaluating patients as LASIK candidates, lens surgery easier with wavefront analysis


    Figure 1: Patient with 20/10.
    Jacksonville, FL-Wavefront technology is the tool of the future to determine the total optical system of the eye, according to Arun Gulani, MD.

    This technology will replace sphere, astigmatism, cylinder, and axis to determine the refractive error in the near future, he continued. Not only does it go beyond these conventional terms but it may change the language of clinical practice, too.

    Dr. Gulani discussed the technology'spotential impact on LASIK, phakic implants, and LASIK complications.

    "Wavefront is a very important tool in our armamentarium of preoperative and postoperative patient care," said Dr. Gu-lani, who uses the Zywave sys-tem (Bausch & Lomb Surgical). "LASIK has been refined to the point that we are at the doorstep of 'super vision.' We are aiming for beyond what was once considered to be perfection. I believe that we are only seeing the tip of the iceberg regarding wavefront applications."

    "I use wavefront for preoperative evaluations to differentiate good from poor LASIK candidates," explained Dr. Gulani, chief of cornea external disease and director, refractive surgery, University of Florida, Jacksonville.

    A diagnostic toolDr. Gulani explained that with this technology he is able to differentiate patients with known contraindications for LASIK-such as early form fruste keratoconus-from those with very high astigmatism.

    "In these patients, who are difficult to distinguish clinically, wavefront can be an important tool to solve this subtle diagnostic dilemma," Dr. Gulani said. "In patients with keratoconus, coma or third-order aberrations are prevalent in the wavefront pattern. An off-centered point-spread function often can be seen, because increased coma causes a shift in the retinal image.

    "In contrast, in patients with high astigmatism the initial picture may resemble early keratoconus, but the point-spread function reveals a picture that is normal for high astigmatism," he said. "Also, when the defocus and astigmatism is compensated, there is not a great deal of coma compared with keratoconus."

    Another important use for wavefront technology is for determining the differences between patients who have had LASIK and are extremely satisfied with the visual results and those who have undergone LASIK with resultant 20/20 vision yet are unhappy with the visual result.

    Dr. Gulani described a patient who had an uncomplicated LASIK procedure with 20/20 visual acuity and was happy with the results. If wavefront-guided LASIK had been performed, the patient may have been unhappy.


    Dr. Gulani
    "LASIK by itself induces higher-order aberrations, such as spherical aberrations," he said. "Having a higher-order aberration is not necessarily detrimental. Sometimes higher-order aberrations cancel out each other, as is the case with defocus and spherical aberration or astigmatism and coma.

    "In some cases, higher-order aberrations may be beneficial," Dr. Gulani said. "Addressing aberrations simply because they are present may not make the patient happy. The surgeon must determine the cause of the aberration."

    Night-vision evaluationIf a patient with 20/20 vision after LASIK complains of difficulties with night vision, Dr. Gulani questions the patient about the type of visual distortion, streaks or starbursts. If the patient reports seeing streaks, usually astigmatism is the cause, according to Dr. Gulani, and a simple enhancement procedure can be performed. If the patient reports starbursts, wavefront analysis may indicate a higher-order aberration, then wavefront-guided LASIK is indicated.

    However, he cautioned, that even though wavefront has been approved by the FDA for surgery, it is important that surgeons do not over-enthusiastically treat all aberrations.

    "This may not provide good results in every case," he said.

    At present, Dr. Gulani is studying all his post-LASIK patients who have 20/10 vision with wavefront analysis. He is also looking at the tear film and outcomes and comparing them with visual endpoint and satisfaction.

    Dr. Gulani has had experience with phakic implants abroad and has been a medical monitor for three different types of phakic implants. He predicts a future for wavefront technology in association with phakic implants.


    Figures 2, 3: Patient with high astigmatism (top figures). Patient with keratoconus (bottom figures). (Figures courtesy of Arun Gulani, MD)
    "Phakic implants are the future of refractive surgery," he said. "Wavefront will help diagnose, evaluate, and plan implanta-tion of IOLs, including the planning of the designs of the IOLs based on customized requirements."

    Intraoperative wavefront technology should be useful during any surgery in which the center of the cornea is spared. The wavefront will continually guide the surgeon in real time and provide data about when the procedure should be stopped.

    For example, in hyperopic treatments such as laser thermokeratoplasty and conductive keratoplasty, "this will be a dynamic use of the technology intraoperatively," he said.

    Dr. Gulani is enthusiastic about the fu-ture availability of wavefront technology. He acknowledges that the technology comes with a steep understanding curve, but be-yond that will represent a great boon to improved visual outcomes.

    Arun C. Gulani, MD
    Dr. Gulani is director of refractive surgery and chief, cornea & external disease, as well as assistant professor, department of ...

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