EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/387844
EW CORNEA 58 October 2014 by Martin L. Fox, MD, FACS Femto PK: A change in the corneal transplant paradigm of postop astigmatism with more than 75% demonstrating 2.5 diop- ters or less of regular astigmatism. Use of femtosecond laser Using femtosecond laser technology, the corneal surgeon now has the ability to create a precision kera- toplasty outline on the recipient, which is matched on the donor eye. Donor tissue may be prepped intraoperatively by the surgeon or with participating eye banks possess- ing corresponding femtosecond laser technology. The surgeon can evalu- ate the patient clinically and decide which pattern of laser cuts best suits the pathology under consideration. Laser cuts are precise and predict- able, completely eliminating the guess work and unwanted surprises often encountered with manual keratoplasty techniques. PK performed with blade-free femtosecond technology offers patients a substantially shorter pe- riod of visual rehabilitation. When using manual PK methods, it is not unusual for a patient to take upward of a year before achieving sufficient healing and wound stability to allow for manifest refraction or contact lens fitting. It is not unusual for patients to develop high degrees of irregular astigmatism due to unpre- dictable and poor wound healing. Femtosecond keratoplasty has made such issues a thing of the past. In IEK, precise matching of complex donor and recipient tissue planes has allowed for accelerated heal- ing. This allows for the removal of sutures as early as 6 weeks postop- eratively with more than 75% of patients manifesting very acceptable levels of regular astigmatism mea- suring 2.5 D or less. IntraLase laser technology can also allow for safe tissue is very rare, and the donor may be further misshapen due to the distorting tissue pressure applied by the keratoplasty punch. Personal experience In contrast, the femtosecond laser creates a precise, customized cut pat- tern for donor and recipient making use of 3 overlapping components: posterior side cut, lamellar ring cut, and anterior side cut. We have found that the zigzag template has allowed for the best clinical outcomes. We position the initiation of the posterior side cut component at a depth of 75 mi- crons from the recipient endothelial surface. Patients are evaluated preop- eratively to determine sizing and pachymetry. The IntraLase-enabled keratoplasty (IEK) calculator (AMO) allows for the prediction of pro- grammed laser cuts for both donor and recipient. On the day of surgery, patients are first brought to our refractive surgery center where IEK cuts are produced. Once in the OR, the laser cuts are separated with a Sinskey hook, the anterior chamber is entered with a diamond knife, and pathology excision completed with keratoplasty scissors. In a series of 14 consecutive keratoconus cases performed over a 1-year period with iFS zigzag pat- terning, we have documented visual rehabilitation at a 3- to 6-month period of follow-up. The series consisted of patients ranging in age from 22–62 with BSCVA range of CF–20/100. Three-month postop data reveals that 100% of cases were correctable to 20/40 or better with spectacles with 64% achieving correctable vision of 20/25 or better. More impressive has been the level 1 year, and high levels of irregular astigmatism and wound instability, among others. Utilization of the iFS Advanced Femtosecond Laser (Abbott Medical Optics, AMO, Santa Ana, Calif.) in my practice has eliminated most of these elements due to the ability to produce precisely matching donor and host shapes and enhance the healing wound interface. Manual PK surgery involves creating a spherical wound on the recipient eye using a trephine applied to the cornea. The surgeon then harvests a corneal button 0.25–0.50 mm larger from the donor eye using a tissue punch. A perfect fit between the recipient and donor T he advent of femtosecond (FS) laser technology has changed the landscape of modern corneal transplan- tation surgery. Laser corneal transplant surgery produces con- sistently excellent outcomes with numerous benefits for the patient, including a significantly shor - er healing time, superior wound integrity, and lower levels of regular astigmatism. Manual penetrating keratoplasty (PK) surgery is an inexact science historically plagued by its inherent unpredictability. Problems often en- countered with manual techniques include graft/host-sizing disparity, prolonged recovery time of up to 23-year-old BM with advanced KCS Postoperative, 9.2 mm zigzag Source (all): Martin L. Fox, MD, FACS "Laser corneal transplant surgery produces consistently excellent outcomes with numerous benefits for the patient including a significantly shorter healing time, superior wound integrity, and lower levels of regular astigmatism." –Martin L. Fox, MD, FACS