Analysis of videokeratography after penetrating keratoplasty: topographic characteristics and effects of removing running sutures.

OBJECTIVE

Previous studies have shown that removal of running sutures after penetrating keratoplasty causes unpredictable changes in astigmatism. The current study was conducted to investigate whether computer-assisted videokeratography is beneficial for predicting visual outcomes after running sutures are removed.

DESIGN

The design was that of a prospective clinical study.

PARTICIPANTS

The authors prospectively studied 29 consecutive eyes undergoing a 10-0 nylon running suture removal after penetrating keratoplasty.

INTERVENTIONS

Videokeratography was performed before, 1 week, 1 month, and 3 months after removal of sutures.

MAIN OUTCOME MEASURES

Changes in refractive and topographic astigmatism after suture removal were measured. Topographic patterns and their quantitative descriptors also were analyzed.

RESULTS

An asymmetric bowtie was the most common videokeratography pattern both before and after suture removal. After suture removal, the incidence of peripheral corneal steepening increased significantly (2 vs. 21 eyes, P < 0.0001), and that of focal flattening of the midperipheral cornea decreased (13 vs. 5 eyes, P = 0.046). The mean topographic astigmatism, surface regularity index, and corrected visual acuity were improved significantly by suture removal in eyes that had localized flattening but not in eyes without this finding. Eyes having either skewed axis in astigmatism or topographic astigmatism of more than 9 diopters also showed significant decreases in astigmatism.

CONCLUSIONS

Suture removal after keratoplasty is advantageous for both reducing astigmatism and normalizing topography, especially in eyes that have localized flattening of the midperipheral cornea. Predictability of visual outcomes of a running suture removal in postkeratoplasty eyes may be improved by the use of videokeratography.