Rapid sequential corneal topography evaluation of selective suture removal in the management of post-keratoplasty astigmatism

Abstract Body:

Purpose: Both penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) can result in high levels of postoperative astigmatism. The use of interrupted sutures to secure the graft-host junction allows for the selective removal of sutures at the steep meridian to reduce post-operative astigmatism. There is limited evidence that the same day following suture removal, corneal topography can accurately identify the next pair of sutures requiring removal (Sarhan 2010). However, this remains controversial. Hence, we seek to evaluate the same-day astigmatic effect of corneal topography-guided selective suture removal as compared with repeat topography 4-6 weeks later in PK and DALK patients.

Study Design: Prospective, multi-centre, non-randomized study.

Methods: A total of 30 consecutive PK or DALK patients undergoing selective suture removal for management of high post-keratoplasty astigmatism (> 3D of Cylinder) were included in this study. Following a set time period after PK or DALK procedures, topography-guided selective suture removal in the steep meridian was carried out. Topography was repeated after 30-40 min and again 4-6 weeks later. The tight sutures requiring removal were identified at each session and compared, and the sutures were removed at the 4-6 week mark. The primary outcome measures were the topographic (via Pentacam) and refractive astigmatism (using automated and manifest refraction) measured at both visits. The difference was considered insignificant if the axis of sutures requiring removal was < 22.5° (given 16 interrupted sutures). The secondary outcome measure was best corrected visual acuity (BCVA). Complication rates and deleterious side effects were also documented.

Results: There was a reduction of astigmatism after suture removal, resulting in improvement of BCVA (p < 0.05). The difference in remaining topographic astigmatism between 30-40 min and 4-6 weeks after suture removal was not statistically significant (p > 0.05) in PK and DALK patients.

Conclusions: Same-day topography following suture removal can define the next set of sutures to be removed with considerable accuracy to reduce the remaining astigmatism. This can reduce the number of follow-up visits necessary to achieve minimal achievable astigmatism and can shorten the post-keratoplasty visual rehabilitation period.