Laser Assisted Keratoplasty in Rapidly Progressive Keratoconus

A 30 year old car salesman presented in August 2011 with history of a rapidly progressive ectactic dystrophy which was creating a significant impact on visual function and the ability to work. Patient was wearing a hybrid contact lens with reasonable comfort.

Examination:

Spectacle corrected visual acuity was 20/100 OD with -2.75-3.00 X 60 and 20/20 with -4.50-3.00 X 112 OS.

Slit lamp evaluation revealed advanced oval sagging Keratoconus OD greater than OS (See Figure 1). Pentacam topographic analysis confirmed morphology of Pellucid Marginal Degeneration in both eyes. In the right eye there was a marked 68 diopter corneal mid periphery associated with an associated corneal thickness of 449 microns. The left eye had similar but somewhat less advanced findings. The remainder of the ocular examination was unremarkable for both eyes.


The patient was counseled as to the nature of his condition and it was advised that considering his age that he was both at risk for further deterioration as well as declining visual function. It was advised that he consider implantation of INTACS intrastromal rings followed by subsequent Collagen Crosslinking to prevent further progression.

The patient presented one year later in August of 2012 at which time he presented with complaints of worsening vision and contact lens intolerance. At this time he requested INTACS surgery for the right eye. Clinical evaluation was compatible with significant progression of the disease with global steepening of the cornea now apparent with para central power of 75.0 diopters (Figure 2). Associated thinning had increased below as well to a thinnest pachmetry of approximately 210 microns.


The patient was counseled as to the rapidly progressive nature of his disease. At this level of central steepening INTACS intrastromal ring implantation was no longer a viable option. Femtosecond laser assisted penetrating keratoplasty was advised as the only logical alternative.

The LAK procedure was performed on September 25, 2012 at the Clarity Refractive Center. Prior calculated femtosecond laser cuts were placed in the recipient cornea using a Zigzag shape template making use of a 9.2mm anterior side cut. The outline was deliberately decentered downward to allow for complete excision of the pathology. The donor cornea was prepared by the eye bank making use of the femtosecond laser and using the cut paradigm used for the recipient. The patient was transferred to the ESSI OR where his keratoplasty was completed uneventfully.

Post-Operative Course

As it is with the overwhelming majority of LAK (Laser Assisted Keratoplasty) cases, this patient made a rapid recovery. Because of the enhanced graft/host healing interface suture removal commenced at the 6-week post-operative visit. At the four-month postoperative visit uncorrected acuity was 20/200 correctible to 20/20 with a refraction of -4.50-0.75×60. Central keratometric readings at this time were 42.2/43.3×81.


Discussion:

This case is instructional from a number of standpoints. It illustrates how rapidly ectactic corneal dystrophies can progress and also demonstrates how femtosecond laser technology has revolutionized corneal transplant surgery allowing even the most advanced cases enjoy impressive and rapid visual rehabilitation.

The patient under review presented with advanced disease findings and was clearly at risk for further progression as well. Such a patient will benefit tremendously from the combination of INTACS intrastromal ring implantation combined with Collagen Corneal Crosslinking therapy. At Clarity we offer both surgical modalities as a combined therapy for advanced keratoconic disease. Had our patient elected to proceed with our original recommendation he might have avoided the need of eventual keratoplasty as his condition progressed aggressively in the year following his original consultation.

The adaptation of Intralase femtosecond technology to corneal transplantation surgery has improved patient outcomes as well as recovery. With Intralase enabled keratoplasty the surgeon can design a pattern of complexed cuts consisting of posterior, lamellar ring and anterior side cut components. Surgery can make use established top hat, mushroom or zigzag templates guided by corneal diameter and pachymetry or the surgeon may design a completely customized pattern to suit the individual needs of the patient. Surgical pattern decisions are then forward to our eye bank where matching Intralase cuts are used in the preparation of donor tissue. For this particular case a zigzag pattern was selected in that it served to create an extended graft host interface for better apposition in a case where the disease process had extended well into the inferior one third of the cornea.

IEK or Laser assisted keratoplasty allows for better graft host apposition and with it a very significant reduction in unwanted post keratoplasty astigmatism. More importantly, pattern incisions allow for very rapid healing and visual rehabilitation. It is not unusual to see post IEK patients able to achieve excellent spectacle corrected acuity as early as 90 days after keratoplasty—something unheard of before the advent of Intralase femtosecond laser technology.

 

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