Rapid sequential corneal topography evaluation of selective suture removal in the management of post-keratoplasty astigmatism
Choi, Christopher Hyun-Bae
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Penetrating keratoplasty is a full-thickness corneal transplant procedure with a relatively long post-operative visual rehabilitation period. Post-operative corneal astigmatism often causes refractive error resulting in suboptimal vision, despite a clear graft. In order to reduce this issue, surgeons selectively remove sutures from the transplanted cornea to manipulate and control the levels of post-operative astigmatism present. In order to identify tight sutures causing astigmatism, corneal topography instruments have been developed which use reflected light patterns to reconstruct topographical images of the corneal surface and provide measurements of corneal steepness and astigmatism. Currently, standard conventions limit suture removal to one to two sutures per visit at an interval between four and six weeks. This experiment sought to determine the feasibility of multiple suture removal following corneal transplant by evaluating the change in astigmatism occurring immediately after suture removal in corneal transplant patients and comparing the change to any occurring one month later. Four separate samples were obtained and analyzed to determine if topography-based decision immediately post-suture removal matched suture removal decision one month later. Topography-guided decisions immediately following suture removal incorrectly identified the appropriate subsequent suture in all samples. Data was analyzed using Fisher’s exact test to determine statistical probability of results, and there was a statistically significant difference between topography-based decision immediately after suture removal and standard topography-based decision at one month. This demonstrated that the period of time immediately following suture removal was not reliable in determining the correct subsequent suture to be removed. Limitations of this study included a small patient sample size, potential graft-host junction override in samples, and the weight of subjective determination by the surgeon. While penetrating keratoplasty has been found to be an effective treatment for patients, further research is warranted to investigate the timeline behind corneal astigmatic stability following surgery and to identify opportunities to shorten long rehabilitation periods.