January consultation # 3

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Patients with very high astigmatism and myopia have challenging optical problems with spectacles, contact lenses, and refractive surgery. I believe the best option for correction of this patient's refractive error is a pIOL. Even though pIOLs are not available in toric designs in the United States, I believe the surgical approach here was reasonable. Based on current available technology, I would have likely chosen a 6.0 mm spherical Verisyse pIOL (AMO), aiming for an SE of plano. I would have also implanted the pIOL through a superior corneoscleral incision. When the astigmatism stabilizes, which typically occurs 6 to 9 months later, I would perform a LASIK enhancement.

The main problem in this case seems to be residual astigmatism. There appears to have been undercorrection of the astigmatism based on what was planned with the pIOL. I would first check to make sure that the pIOLs are well centered in both eyes and are in the originally planned orientation to ensure the residual astigmatism is not from pIOL decentration or rotational misalignment. Either problem can lead to glare and halo as well as the residual correction and can be improved by repositioning the pIOL. I have seen more glare and halo with the 5.0 mm pIOL, even in patients with small pupils, because of the potential for edge effects with minimal decentration that likely are outside the optical zone needed to take full advantage of the Stiles-Crawford effect.

If the pIOLs are reasonably well centered and aligned, an attempt to determine whether the patient's symptoms are tolerable with spectacle or contact lens correction of the residual astigmatism is warranted. With a 5.0 mm corneoscleral incision, some wound astigmatic effects can be seen for several months. Thus, I would delay laser vision correction to correct the residual astigmatism until the astigmatism is stable. This will also give the patient and surgeon an idea of whether the glare and halo can be resolved by improving the residual astigmatism and coma induced by the superior incision present on postoperative topography. If the glare and halo are tolerated in spectacles or contact lenses, wavefront directed laser vision correction could be performed 6 months postoperatively and could significantly improve the UCVA and patient satisfaction. Our group presented the results of laser vision correction in 22 eyes with pIOLs, reporting a reduction in residual astigmatism from 1.70 D after pIOL implantation to 0.25 D after laser vision correction with the Visx Star S4 laser (AMO/Visx) (D.R. Hardten, MD, et al. “Results of Laser Vision Correction in Eyes with Intraocular Lenses,” presented at the XXV Congress of the European Society of Cataract & Refractive Surgeons, Stockholm, Sweden, September 2007).

If the patient's symptoms are not tolerated with spectacle or contact lens correction, a trial of reducing pupil size is warranted. This should be attempted once the patient is through the early postoperative period as the nonsteroidal and steroidal agents used postoperatively can cause pupil dilation, which will improve a few months after these agents are discontinued. A small amount of decentration of a 5.0 mm pIOL can result in night symptoms. The effective optical zone may not be large enough to take full advantage of the Stiles-Crawford effect for this degree of difference between the corrected and the uncorrected regions of the visual system if there is some decentration of the IOL. Brimonidine tartrate 0.15% (Alphagan P) and dilute pilocarpine may be helpful. If these are not tolerated and the size of the pIOL optical zone is still thought to be an issue, an exchange for a 6.0 mm spherical IOL with laser vision correction performed later could be considered. Removal of the IOL and a return to spectacle or contact lens wear could be contemplated, although most patients would not like the return to a high level of ametropia.