Pilot Study: The Effect of Radial Sutures on High Astigmatism After Penetrating Keratoplasty

1. Pilot Study: The Effect of Radial Sutures on High Astigmatism After Penetrating Keratoplasty Maayan E. Keshet, M.D. Maggie B. Hymowitz, M.D. John J. Kim, M.D. Albert Einstein College of Medicine Montefiore Medical Center Neither author has any financial interest to disclose

2. Introduction • Patients with high degrees of astigmatism present special challenges for the refractive surgeon and clinician1, 2, 3. • Although a variety of surgical options are available for correction of mild astigmatism (less than -2.50 diopters), there is no effective surgical way to correct higher degrees of astigmatism (greater than -5.00 diopters). • Particularly affected are post-corneal transplant patients who often suffer from high cylindrical errors4.

3. Introduction • As opposed to the incisional (AK and LRI), that function by flattening the cornea’s steep meridian, we attempted a suturing technique which would steepen the cornea’s flat meridian. • Unlike AK, LRI’s, PRK, LASIK, and toric IOLs, the procedure was reversible – the prolene sutures could be easily removed at the slit lamp. • It also avoided complications such corneal ectasia, significant scarring, or haze. • Furthermore, the corneal sutures were able to induce high levels of astigmatism that effect powerful cylindrical change in the desired axis.

4. Methods • Standard IRB approval was obtained (#07-10-357E) • Post-PKP patients routinely examined in the ophthalmology clinic were screened for astigmatic refractive errors ≥ -5.00 diopters. • Those choosing to participate in the study were consented and enrolled. • All participants had their best-corrected and uncorrected refractive error determined, along with auto-refraction and corneal topography at the following time intervals: before the procedure (pre-suture), post-suture, at one day, one week, one month and three month post-procedure.

5. Methods • The axis of the flat meridian of the cornea was determined with an auto-refractor and the NIDK MagellanMapper corneal topographer. • Once prepped and draped in the usual sterile fashion, topical 2% lidocaine jelly and a lid speculum were placed in the study eye. • Two radial 10-0 Prolene sutures were placed along the flat corneal meridian at 180º from one another. • One drop of Vigamox was applied to the eye before and after the procedure. • Subjects were instructed to use one drop of Vigamox, four times a day in the study eye for one week.

6. Results • Subject 1 Pre-suture Post-suture presuture Post-op day #1 Post-op week #1 Post-op month #1

7. Results • Subject 1

8. Results • Subject 2 Pre-suture Post-suture Post-op day #1 Post-op week #1 Post-op month #1

9. Results • Subject 2

10. Results • Subject 3 Pre-suture Post-suture Post-op day #1 Post-op month #1

11. Results • Subject 3 *Sutures removed due to loosening, severe photophobia and irritation

12. Conclusions • Although the Prolene radial sutures improved astigmatism considerably in the first day and week post-operatively in our three subjects, their effects diminished over time. • Loosening of sutures or dynamics of corneal elasticity may have limited the ability of two simple prolene sutures to correct high diopter post-keratectomy astigmatism.