Implantation of a customized toric intraocular lens for correction of post-keratoplasty astigmatism

Abstract

Purpose: To report visual and refractive outcomes, and endothelial cell loss following primary and secondary 'piggyback' toric intraocular lens (IOL) implantation in patients with high post-penetrating keratoplasty (PK) astigmatism.

Methods: Prospective case series. Nine eyes of nine patients with post-PK astigmatism were consecutively recruited for implantation of a customized toric IOL. Six underwent simultaneous phacoemulsification (PE) and three pseudophakic eyes had a secondary 'piggyback' toric IOL implanted in the ciliary sulcus. Mean follow-up time was 17.2±7.7 months. Pre- and post-operative uncorrected (UDVA) and best-corrected (BDVA) distance visual acuities and refractive errors were collected for comparison. Cartesian astigmatic vectors were calculated to identify a change in the magnitude of astigmatism pre- compared to postoperatively. Pre- and post-operative endothelial cell counts were also collected for analysis.

Results: UDVA (logMAR) improved from 1.13±0.51 preoperatively to 0.48±0.24 postoperatively (P-value=0.003). There was no significant change in BDVA (P-value=0.905) from 0.31±0.27 to 0.26±0.19. Corneal astigmatism preoperatively was 6.57±4.40 diopters (D). Post-operative refractive cylinder was 0.83±1.09 D compared to 3.89±4.01 D preoperatively (P=0.039). Analysis of astigmatic Cartesian x and y coordinates found a significant reduction postoperatively compared to preoperatively (P=0.005 and P=0.002), respectively. Mean endothelial cell loss was 9.9%.

Conclusion: Implantation of a customized primary or secondary 'piggyback' toric IOL serves as an effective modality in treating patients with high post-PK astigmatism.

Figure 1

Post-operative compared to pre-operative UDVA of individual patients.

Figure 2

Scatter plot of polar astigmatic vectors for pre-operative corneal astigmatism (a) and post-operative refractive cylindrical error in the corneal plane (b). Note the larger magnitude and distribution of pre-operative astigmatism compared to post-operative result, clustered around 0. The origin represents an eye that is free of astigmatism. Red point intimates mean value. Scale in D.

Figure 3

Chart of mean Cartesian x and y coordinates for pre-operative corneal astigmatism and post-operative refractive cylindrical error in the corneal plane. Both x and y coordinates are closer to 0 with a significant reduction in variance, representing a significant reduction in the post-operative astigmatism.