Femtosecond Laser-Assisted Intrastromal Astigmatic Keratotomy for Treatment of Astigmatism Post-Penetrating Keratoplasty

Yeung, Season

Femtosecond Laser-Assisted Intrastromal Astigmatic Keratotomy for Treatment of Astigmatism Post-Penetrating Keratoplasty

Tuesday, April 29, 2014: 8:45 AM

Room 151B (Boston Convention and Exhibition Center)

Season Tse Wing Yeung, MBBS, FRANZCO, The University of Ottawa Eye Institute, Ottawa, ON, Canada

Ronan J. Conlon, MD, University of Ottawa, Ottawa, ON, Canada

Salina Teja, MD, University of Ottawa Eye Institute, Ottawa, ON, Canada

Joshua C. Teichman, MD, MPH, University of Ottawa Eye Institute, Oakville, ON, Canada

George Mintsioulis, MD Ottawa, ON, Canada

W. Bruce Jackson, MD, FRCSC, Univ of Ottawa Eye Inst, Ottawa Hospital, Ottawa, Ontario, Canada

Kashif Baig, MD, MBA, Ottawa Eye Institute, Ottawa, ON, Canada

Narrative Responses:

Purpose
The purpose of this study is to report the outcomes of the correction of astigmatism with femtosecond laser-assisted intrastromal astigmatic keratotomy in patients with previous penetrating keratoplasty (PKP).

Methods
The present study is a prospective interventional case series of 20 patients with known astigmatism post-PKP. Femtosecond laser-assisted arcuate incisions will be generated such that the incision will extend from 90um beneath the epithelial surface to 90um above the endothelium. The main outcomes measures include uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction (MR), and topographic indices. In addition, the correlation between incision length and change in topographic indices and manifest refraction will be elucidated, and the impact on treatment outcomes from variable corneal graft diameters will be examined.

Results
The mean preoperative UDVA and CDVA were 0.58 ± 0.12 logMAR and 0.05 ± 0.05 logMAR, respectively. The mean topographic cylinder was reduced significantly from 5.30 ± 0.31 dioptres (D) preoperatively to 3.66 ± 0.70D postoperatively (P<0.01). A decrease in mean manifest cylinder (from 5.75 ± 0.61D preoperatively to 4.30 ± 1.01D postoperatively) was observed, however the results were not statistically significant. Similarly, there was no statistically difference in the preoperative and postoperative UDVA, CDVA, and topographic keratometric values. No serious adverse effects were reported.

Conclusion
Femtosecond laser-assisted intrastromal astigmatic keratotomy is a precise and effective technique in reducing corneal astigmatism in post PKP patients. The proposed technique has a better safety profile than transepithelial arcuate incisions as the risks associated with incisions that penetrate Bowman’s membrane are avoided.