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Conductive Conductive Keratoplasty for the Keratoplasty for the Correction of Low to Correction of Low to Moderate Hyperopia: Moderate Hyperopia: U.S. Clinical Trial U.S. Clinical Trial 12-Month Results 12-Month Results

U.S. Clinical Investigators

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Conductive Keratoplasty for the Correction of Low to Moderate Hyperopia: U.S. Clinical Trial 12-Month Results. Vera Kowal, MD Richard Lindstrom, MD Robert Maloney, MD Edward Manche, MD Roger Meyer, MD Thomas Samuleson, MD Timothy Schneider, MD Kaz Soong, MD Alan Sugar, MD. - PowerPoint PPT Presentation

Text of U.S. Clinical Investigators

  • Conductive Keratoplasty for the Correction of Low to Moderate Hyperopia: U.S. Clinical Trial 12-Month Results

  • U.S. Clinical InvestigatorsVera Kowal, MDRichard Lindstrom, MDRobert Maloney, MDEdward Manche, MDRoger Meyer, MDThomas Samuleson, MDTimothy Schneider, MDKaz Soong, MDAlan Sugar, MDPenny Asbell, MDStephen Brint, MDWilliam Culbertson, MDJonathan Davidorf, MDElizabeth Davis, MDDan Durrie, MDR. Bruce Grene, MDPeter Hersh, MDDavid Hardten, MDMarguerite McDonald, MD Medical Monitor

  • Treats hyperopia, astigmatism, presbyopia and over/under LASIK correctionsInduces permanent collagen shrinkageCreates a column of treatmentUtilizes corneas conductive propertiesConductive Keratoplasty Features

  • ViewPoint CK System

  • The Keratoplast tip (90 m wide, 450 m long) with coated stop at the distal end

    (shown next to a 7-0 suture)

  • Conductive Keratoplasty (CK)

  • US FDA Phase III Study400 PatientsSpherical hyperopia 0.75 D to 3.00 D < 0.75 D of cylinderNo prior refractive surgeryNo significant ocular/physical history24 Month Follow-Up

    Study Objective

  • Demographics

  • Simple ProcedureInstill topical anesthesiaInsert lid speculum (return path for energy)Mark eyeApply treatment

    Total time less than 5 minutes

  • Conductive Keratoplasty (CK)

  • 6 mm OZNumber, Location, and Sequence of Treatment SpotsSequence264735188 mm OZ7 mm OZ32 spots(2.375 to 3.00 D)24 spots(1.75 to 2.25 D)16 spots(1.00 to 1.625 D)8 spots(0.75 to 0.875 D)

  • Slit Lamp Photo 1 Hour After CKSmall leucomaVisible striae

  • Postoperative UCVA Over Time

  • Accuracy of Achieved Refraction

  • MRSE Stability through 12 MonthsPatients with Consecutive VisitsMean Change 0.25 D (0.50) 0.11 D (0.41) 0.11 D (0.35)in MRSEConf. Interval 0.19, 0.31 0.07, 0.15 0.07, 0.15

  • Safety Variables

    12 MonthsN=383 2 lines lost BSCVA2% > 2 lines lost BSCVA0.0% BSCVA Worse than 20/400.0% Increase >2.00 D Cylinder0.3% Pre-Op 20/20, Post-op 20/25 0.0%

  • Induced Cylinder >2.00 D CK vs. Non-Contact LTK1Sunrise LTK FDA Clinical Study, 2Conductive Keratoplasty 12-Month FDA Clinical Study Results.

  • Summary Efficacy VariablesData from patients with single treatment. No retreatments included.

  • Conductive Keratoplasty: Case StudyPreoperative50 year oldFemaleAfrican AmericanGood healthNo ocular history6 mm pachymetry: 556 mIOP: 15 mm Hg

    PreoperativeUCVAD: 20/125UCVAN: J12Manifest RX:+ 3.25 0.75 X 130Cycloplegic RX:+ 3.25 0.25 X 130BSCVAD: 20/25

  • Conductive Keratoplasty: Case StudyOperativeInstilled three drops topical anesthesiaInserted lid speculumApplied 32 treatment spotsRemoved lid speculumInstilled NSAID and antibioticImmediate K-Readings:51.75 @ 180 X 49.62 @90

  • Conductive Keratoplasty: Case Study1 Day Post-OperativeUCVAD: 20/32UCVAN: J7Manifest RX:+ 1.50 0.50 X 120BSCVAD: 20/20BSCVAN: J2Slit Lamp: small epithelial defects

  • Conductive Keratoplasty: Case Study1 Month Post-OperativeUCVAD: 20/20UCVAN: J2Manifest RX:- 0.25 0.75 X 125BSCVAD: 20/20BSCVAN: J1Slit Lamp Exam: WNL

  • Conductive Keratoplasty: Case Study3 Month Post-OperativeUCVAD: 20/32UCVAN: J2Manifest RX:plano 1.00 X 125BSCVAD: 20/16BSCVAN: J1Slit Lamp Exam: WNL

  • Conductive Keratoplasty: Case Study6 Month Post-OperativeUCVAD: 20/30UCVAN: J2Manifest RX:+ 0.25 0.75 X 125BSCVAD: 20/25BSCVAN: J1Slit Lamp Exam: WNL

  • Conductive Keratoplasty: Case Study12 Month Post-OperativeUCVAD: 20/20UCVAN: J2Manifest RX:+ 0.25 0.25 X 110BSCVAD: 20/16BSCVAN: J1Slit Lamp Exam: WNL

  • Conductive Keratoplasty: Case StudyPreoperative50 year oldFemaleUCVAD: 20/125UCVAN: J12Manifest RX:+ 3.25 0.75 X 130BSCVAD: 20/25

    12 Months Post-op

    UCVAD: 20/20UCVAN: J2Manifest RX:+ 0.25 0.25 X 110BSCVAD: 20/16No retreatment. Spherical correction only

  • Corneal Topography: Case StudyPreoperative

    12 month Post-op

  • Confocal View Of CKFolds Between Treatment SpotsSabry, McDonald, Klyce - 2001

  • Confocal View Of CKDeep CK Treatment With Healthy EndotheliumSabry, McDonald & Klyce - 2001

  • Cylindrical Footprint of CK

  • Summary of Phase III StudyHighly effective comparable to H-LASIKStability at 6 months Safe low rate induced cylinder Penetration depth confirmed by histology, confocal microscopy

  • Summary of Phase III StudyTopography shows central corneal steepening with mid-peripheral flattening Visual axis sparedMulticenter study continues for two years

    Most of these surgeons have have no financial interest in Refractec, Inc. A few investigators participate in a Medical Advisory Board and are paid for their time. Dr. Marguerite McDonald is paid to be the studys medical monitor. The potential applications for Conductive Keratoplasty are for the treatment of hyperopia, astigmatism, presbyopia and fine tuning refractive outcomes of patients who are over/under corrected after LASIK.

    Only the application for the treatment for hyperopia is being studied at this time in the United States, but there are plans to begin a presbyopia and an astigmatism study in the US later this year. Astigmatism and treatments post LASIK are being studied outside the US.

    The method uses radiofrequency energy to generate heat to shrink corneal collagen within the targeted treatment zone. The temperature range of the treated area is 65 to 75 degrees C, which permanently denatures and shrinks collagen.

    A column or cylinder is created deep within the corneal stroma. I will show histology photos that reveal the cylindrical footprint later in this presentation.

    The CK procedure is performed with the ViewPoint CK System shown here. The console is about the size of a VCR and is portable.

    There is a choice of two lid specula: Lancaster type and Barraquer type. The lid speculum acts as the electrical return path.

    The Keratoplast tip (shown in next slide) is held in the handpiece and is used to deliver radio frequency energy (350 kHz) into the corneal stroma at 8 to 32 treatment points.

    This is the Keratoplast tip that delivers low energy, radio frequency (350 kHz) current when inserted into the peripheral cornea. It is shown next to a 7-0 suture.

    Note: This is a small animated clip. It will automatically run, however you will need to wait approximately 3 seconds (depending on the speed of the computer you are using). The clip has audio. However, if you do not have audio capabilities the transcript is written below.

    Based on the use of a controlled release of radio frequency energy introduced into the stroma, in conjunction with the eyes natural conductive properties, the temperature of the corneal tissue is increased, and the cornea is gently reshaped.Double click on center to start.

    The FDA required that we treat 50 subjects and follow them for 6 months before we treated the full cohort of 400 eyes. The original 50 eyes in this presentation were treated in the range of +1 to +4 diopters of hyperopia. Later we adjusted the nomogram to treat hyperopia in the range of +0.75 to +3.00 diopters.

    The intended refraction was plano for all eyes.

    We have now closed enrollment in the study.

    Here are demographics and baseline information on the 401 treated eyes.

    Today, I will report on the data up to 12 months post-op.

    CK is a very simple procedure to perform and takes less than 5 minutes from the time the speculum is inserted to the time the speculum is removed.

    Note: This is a small animated clip. It will automatically run, however you will need to wait approximately 3 seconds (depending on the speed of the computer you are using). The clip has audio. However, if you do not have audio capabilities the transcript is written below.

    The optical zone marks of 6, 7 and 8 millimeters act as a template for the treatment application. Once the mark is applied, the surgeon begins applying treatment superiorly and continues until all of the rings of treatment are complete. Striae then begin to form between the treatment spots, creating a band of tightening. It is this tightening of the tissue that produces steepening of the central cornea.

    This shows the number, location, and sequence of treatment spots, also called the nomogram.

    The cornea is first marked with a corneal marker dipped in gentian violet. A circular mark is made on the 7 mm optical zone and hatch marks are made at the 6 and 8 mm optical zones.

    For the lowest amount of correction, 8 spots are placed on the 7 mm optical zone. For correcting 1.00 to 1.625 diopters, 16 spots are placed -- 8 at the 6 mm OZ and another 8 at the 16 mm OZ. For correcting 1.75 to 2.25 diopters, 24 spots are placed -- 8 each at the 6, 7, and 8 mm OZs. And for correcting 2.375 to 3.00 diopters, 24 spots are placed -- 8 each at the 6, 7, and 8 mm optical zones, as for 1.75 to 2.25 diopters of correction, and then 8 more spots are added in between the spots previously made at the 7 mm OZ. Treatment placement is not difficult and proceeds very quickly. All spots can be placed in 5 minutes.

    NOTE: This is a short surgical clip from Dr. Manche. The wrong treatment application is used, however it is the only short clip we have on video. Please feel free to use your own surgical footage here.Double Click to start.

    This is a slit lamp photo from Dr. Durries patient. The photo was taken one hour after treatment and the rose bengal marks are still visible. Notice that the surface leucomas are very small since all of the energy is delivered deep within the stroma. Notice also the visible band of striae that form between the treatment spots.

    Uncorrected visual acuity improved with time. At 12 months, 56% were 20/20 or better, 75% were 20/25 or better, and 92% were 20/40 or better. At 12 months, 63% of eyes were within 0.50 D of intended correction (plano), 89% were within 1.00 D, and 99% were within 2.00 D. Stability appeared to be achieved by 6 months with a little over one-tenth of a diopter (0.11) change in the 6 to 9 month interval and the same change (stable) in the 9 to 12 month interval.

    Mean change testing was done by paired differences comparisons. Overall, this shows the excellent stability that follows the CK procedure.The CK data to date demonstrate an excellent safety profile with seven eyes (2%) losing two lines of BSCVA. No eye lost more than 2 lines of BSCVA.

    Only one of 355 eyes had more than 2 diopters of cylinder induced. The rate of induced cylinder is about the same after CK as after LTK.

    No eye had BSCVA worse than 20/40.

    No eye that had 20/20 or better BSCVA preoperatively was worse than 20/25 postoperatively.

    Note: N = 383 (not 355) because safety data was acquired from first 54 eyes (old nomogram) plus the current nomogram eyes.

    This compares the Sunrise non-contact LTK results with the CK results for the incidence of induced cylinder of more than 2.00 diopters. The percentages at each follow-up time are remarkably similar. (This shows very similar safety with the two techniques, but as we have seen, there is better efficacy and stability with LTK.) Results at 6 and 12 months met all FDA guidelines for uncorrected visual acuity and accuracy of achieved manifest refractive spherical equivalent. Here is a patient case study. Conductive keratoplasty case study. Corneal topography of a typical pre- and post-CK eye. Preoperative MRSE was +3.25 D and UCVA was 20/125. Central steepening surrounded by mid-peripheral flattening can be seen postoperatively. Twelve months post-op, this eye had MRSE = +0.25 D and UCVA of 20/20. Drs. Sabry, McDonald and Klyce have studied the effects of CK using confocal microscopy. Here you can see the effects of CK within the cornea. There is a prominent stromal fold in the striae between the two CK treatment spots.Additionally, you can see the depth of the treatment application however, not at the risk of damaging the corneal endothelium.These histology views show that the footprint in the corneal stroma after treatment extends to approximately 80% of the depth of the mid-peripheral cornea. Deep thermal penetration in the treatment zone (without damaging the endothelium) is desirable for permanent collagen shrinkage, which is expected to reduce postoperative regression.

    The CK targeted treatment zone in the stroma reaches a temperature consistent with optimal collagen shrinkage (65 to 75 C). The energy emitted from the CK probe is greatest at the tip of the probe. During an energy pulse, the thermal effect proceeds from the point of the probe up the shaft as it finds the path of least resistance (from the bottom, up). The result is a cylindrical thermal effect that has almost no axial component. Thus the resulting footprint is cylindrical.

    In contrast, the Hyperion noncontact LTK technique generates the greatest amount of heat at the surface of the cornea because of the high absorption of light energy in water (the cornea is mostly water). The Ho:YAG beam is attenuated as it passes through the cornea so that the heat energy diffuses radially and axially into the tissue. The result is a cone-shaped collagen shrinkage zone (Koch, et al., J Refract Surg 1996), with corneal denaturation decreasing from top to bottom. While studies have not been published on the depth of the LTK footprint, the penetration is believed to be more shallow.

    Deep penetration with a conical configuration could be expected to also cause surface damage. ???correct JP

    This multicenter clinical study showed that CK is highly effective in decreasing low to moderate hyperopia. The outcomes are similar to those seen after hyperopic LASIK. Stability appeared to be achieved at 6 months. The procedure was very safe -- induction of cylinder of more than 2.00 D was 0.5%, and preoperative BSCVA was maintained.

    Confocal microscopy and histology showed a deep, cylindrical footprint, which is compatible with a more effective and longer-lasting result. Corneal topography showed central corneal steepening with mid-peripheral flattening.

    As a non-excimer laser technique for correcting hyperopia, CK spares the visual axis (preserves the central cornea) and does not induce flap-related complications. Additional staff members are not needed as with LASIK because the procedure is not complex.

    The range of correction, however, is limited to low hyperopia, and the surgeon must turn to LASIK, phakic IOL implantation, clear lens extraction, or other procedure for patients outside of the treatment range of CK.

    This multicenter study continues for a total of two years. This multicenter clinical study showed that CK is highly effective in decreasing low to moderate hyperopia. The outcomes are similar to those seen after hyperopic LASIK. Stability appeared to be achieved at 6 months. The procedure was very safe -- induction of cylinder of more than 2.00 D was 0.5%, and preoperative BSCVA was maintained.

    Confocal microscopy and histology showed a deep, cylindrical footprint, which is compatible with a more effective and longer-lasting result. Corneal topography showed central corneal steepening with mid-peripheral flattening.

    As a non-excimer laser technique for correcting hyperopia, CK spares the visual axis (preserves the central cornea) and does not induce flap-related complications. Additional staff members are not needed as with LASIK because the procedure is not complex.

    The range of correction, however, is limited to low hyperopia, and the surgeon must turn to LASIK, phakic IOL implantation, clear lens extraction, or other procedure for patients outside of the treatment range of CK.

    This multicenter study continues for a total of two years.