Toric IOLs improve astigmatism after myopic, hyperopic laser surgery
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Patients who had underwent toric IOL implantation after previous excimer laser corneal refractive surgery showed significantly decreased astigmatism.
“Correcting corneal astigmatism in post-LASIK eyes can be challenging due to the presence of varying amounts of irregular astigmatism,” Danmin Cao, MD, from Baylor College of Medicine, Houston, Texas, and colleagues wrote. “To obtain optimal results with toric IOLs in eyes with previous LASIK/PRK, it is paramount to carefully assess the preoperative corneal astigmatism.”
The study involved 75 eyes, including 47 patients who had previous myopic LASIK/PRK and 16 patients who had previous hyperopic LASIK/PRK.
Preoperatively, the mean magnitudes of corneal astigmatism were 1.34 D among the myopic treatment group and 1.66 among the hyperopic treatment group. After toric IOL implantation, the mean magnitude values of refractive astigmatism significantly decreased to 0.36 D and 0.34 D, respectively.
The preoperative centroids of corneal astigmatism were 0.31 D at 19 degrees in the myopic treatment group and 0.74 D at 92 degrees in the hyperopic treatment group. Postoperatively, the centroids of refractive astigmatism significantly decreased to 0.12 D at 152 degrees and 0.05 D at 172 degrees, respectively.
“In our study, compared with the preoperative corneal astigmatism, the magnitude of postoperative refractive astigmatism was significantly decreased, and the percentages of eyes with astigmatism 0.50 D [or less] and 1.00 D [or less] significantly increased in both myopic and hyperopic LASIK/PRK groups,” Cao and colleagues wrote.
Perspective
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Sondra Black, OD, FAAO
Millions of people have undergone refractive surgery over the years. These patients underwent LASIK or PRK to enable them to be as glasses-independent as possible. More and more of these patients are now undergoing cataract surgery and expect the same visual freedom that they had prior. One of the important parameters to ensure patient satisfaction is the amount of residual postoperative astigmatism.
This study of 75 patients addressed the success of treating postrefractive patients with a toric IOL. The study included patients who had either myopic or hyperopic LASIK or PRK refractive surgery. Calculations of IOL power in post refractive eyes are not as straightforward as virgin eyes, and, therefore, appropriate formulas need to be used. Postoperatively, they showed that 80% of postmyopic patients and 84% of posthyperopic patients had less than 0.5 D residual astigmatism. This aligned with the success rate of toric IOLs in virgin eyes. This study, therefore, demonstrates that toric IOLs can be used successfully in postrefractive eyes and should be offered as an option to this patient group that has already been known to want to reduce their dependence on glasses.
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