EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/176967
48 EW FEATURE February 2011 Refractive challenges and innovations September 2013 LASIK complications and creation of a free cap by Ellen Stodola EyeWorld Staff Writer AT A GLANCE • Free caps can be a complication when using a microkeratome, but femtosecond laser technology makes this problem less likely to occur. • When reacting to a free cap and treating a patient, additional cuts with a microkeratome or femtosecond laser could run the risk of creating more damage. • Photorefractive keratectomy (PRK) can be a viable option for treatment for aborted LASIK flaps. • When a complication occurs, it's important to consider possible treatment options and the patient's refractive goals in determining the best path forward. When complications occur, knowing how to deal with the issue and a patient's visual goals are key W hen performing LASIK and other procedures, there is always the possibility of a complication, and complications must be handled accordingly to try to ensure the best possible outcome and satisfaction of the patient. Neel Desai, MD, director of cornea and refractive surgery, Eye Institute of West Florida, Largo, Fla., described a complication that occurred during a LASIK procedure on a presbyopic personal injury attorney when a free cap was created. Louis Probst, MD, national medical director, TLC Laser Eye Centers, Westchester, Ill., and James Salz, MD, clinical professor of ophthalmology, University of Southern California, Los Angeles, commented on the specifics of the case and how they might have reacted in this situation. Case background Dr. Desai's 44-year-old female myopic patient came to him for a LASIK evaluation, wanting to be spectacle and contact lens independent for both distance and near vision. The patient's manifest refraction was –4.00 sphere OD and –3.75 sphere OS, and both crystalline lenses were clear. Dr. Desai had a discussion with the patient about the options, including clear lensectomy with presbyopia-correcting IOLs versus the LASIK options, but since she had previously used monovision contact lenses, she was determined to have LASIK for monovision. Both femtosecond-assisted LASIK and conventional LASIK options were offered, but the patient elected to have flaps created with a traditional microkeratome, as her friends and family had previously. When LASIK was performed, in this case with an Amadeus II microkeratome (Ziemer Ophthalmic Dr. Desai experienced a complication during a LASIK procedure when a free cap was created that was about 128Ð136 microns in depth, with a diameter of 5 mm centered on the cornea. Source: Neel Desai, MD Systems, Port, Switzerland) with a 140-micron head, the dominant right eye saw no complications. However, during flap creation in the non-dominant left eye, a 5 mm shallow free cap was created due to loss of suction. "The treatment was aborted and the free cap replaced, irrigated, and realigned," Dr. Desai said. "Weck-Cel spears were used to wick away interface fluid at the edge of the cap to aid in adherence. A bandage contact lens was placed for seven days." Postoperatively, the patient's right eye was plano and 20/20+, while the left eye MRx was –3.25 to 20/20. The free cap had healed well without striae or epithelial ingrowth. Free cap details clinicians with a flagging of the final D value in hopes of eradicating the uncertainty the various subreadings may have caused; this is, in fact, how the BAD analysis was originally intended to be used. Eye rubbing may be another reason for varied readings from the diagnostic exams, Dr. Thompson said. "Our understanding of the significance of eye rubbing has increased tremendously over the past 20 years. I ask all patients if they rub their eyes and if they do, a subtle diagnostic sign that may have not bothered me becomes a reason to recommend against surgery." Anterior base membrane dystrophy can also cause abnormal-look- ing topographies but result in a normal tomography, Dr. Chu said. "We're still learning so much about the posterior corneal surface." EW Diagnostic continued from page 47 moving forward; a substantial discrepancy or abnormal test "will make us lean more toward surface ablation," he said. "If there are critical measurements that are abnormal, we will advise against surgery altogether." With the Pentacam, any of the five readings that is more than two standard deviations away from the normal population is flagged yellow; three standard deviations away is flagged red. Virtually "no one is going to be comfortable proceeding with surgery" if the final reading is red flagged, Dr. Probst said. Since the Pentacam was introduced a few years ago, particularly with the Belin/Ambrosio Display (BAD), Dr. Probst noticed a "substan- tial increase" in the number of PRK procedures performed industry-wide and a "measurable increase in the non-candidacy rate of patients for LASIK," both of which he attributes to a more conservative approach based on the Pentacam results. While PRK is a "fine procedure," it can be more technically difficult for the surgeon and tougher on the patient, Dr. Probst added. "It's not a nice, slick procedure like LASIK is. There has been a subset of patients who have undergone PRK simply because of a sub-D Pentacam flag who would have been just fine with LASIK." Dr. Probst noted the latest software version of the Pentacam (BAD III) eliminates the various flags on the sub-D readings to provide Dr. Desai said an anterior segment OCT showed that the free cap was about 128–136 microns in central depth, with a diameter of 5 mm centered on the cornea, rendering a second, deeper femto flap a risky option in his estimation. "Even though the LASIK treatment was aborted, the change in refraction suggests that the keratometry was significantly impacted by the free cap alone." Secondary PRK was considered but found less attractive due to the free cap depth, diameter, and risk of further complications with a treatment zone wider than the thinedged free cap and the inherent risk of epi-ingrowth. "Due to flap depth, the patient was encouraged to reconsider lenticular-based options, Editors' note: Dr. Buznego has financial interests with Allergan (Irvine, Calif.) and Bausch + Lomb. The other physicians have no financial interests related to this article. Contact information Buznego: cbuznego19@gmail.com Chu: yrchu@chuvision.com Devgan: devgan@gmail.com Probst: 708-562-4682 Thompson: vance.thompson@vancethompsonvision.com