Understanding and Correcting for Toric IOL Refractive Surprises
Narrative Responses:
Purpose
To accurately determine the optimum amount of toric IOL rotation required after a refractive cylinder surprise. This requirement can be necessary where even perfect placement and selection of the toric implant has occurred.
Methods
Using a new application of free internet software the planning and analysis of astigmatism prior to and after surgery using toric IOLs was investigated. Two cases of postoperative refractive surprise after toric IOL implantation were analyzed to determine the most appropriate course of treatment: rotation of the toric IOL, exchange of the toric IOL or LASIK surgery to correct the remaining refractive error.
Results
Case 1: Preoperative keratometry was 41.87/46.00 @ 94, Alcon SN60T8 +10D 5.25D cyl was implanted with postoperative refraction +1.75/-2.50 x 135. Optimum rotation to reduce refraction to minimum spherocylinder calculated using web calculator was 24 clockwise degrees. Post IOL rotation, refraction was +0.25/-0.25 x 90. Case 2: Preoperative keratometry was 37.87/41.75 @ 13, AMO ZCT400 +24D 4D cyl was implanted with postoperative refraction +0.50/-2.00 x 75. Optimum rotation of 11 degrees clockwise calculated minimum refraction +0.23/-1.45 x 92 which was suboptimal. Hence, LASIK was preferred option and postoperatively the refractive outcome was +0.25/-0.25 x 75
Conclusion
Understanding refractive surprises and how to correct for them after toric IOL implantation can determine the best secondary procedure to achieve optimal visual outcomes.