The majority of our patients who come in for ophthalmic surgery—approximately one-third of cataract surgery patients and one-half to two-thirds of refractive patients—will have some presenting astigmatism that must be addressed to optimize their postoperative UCVA. For this fairly prevalent visual defect, it is best to have an action plan and to follow it during each surgical step. If multifocal IOLs are an integral part of your cataract practice, you will find added benefit from developing and implementing such a plan.

A postoperative astigmatism treatment plan is crucial, because it better equips us to provide our patients with the best possible visual outcome. The patient must be informed that astigmatism is somewhat recalcitrant to treat, and we have a higher rate of retreatments to resolve the defect. If you relay this message to the patient at the beginning of the process, they will be more understanding if retreatment does occur.

When using multifocal IOLs, preexisting astigmatism may cause unwanted side effects. For example, astigmatism on top of a Rezoom IOL (Advanced Medical Optics, Santa Ana, California) increases nighttime halos, and astigmatism on top of a Restor diffractive IOL (Alcon Laboratories, Fort Worth, Texas) affects distance and near vision. Therefore, it is important to be willing to treat astigmatism before placing a multifocal IOL. Ignoring the astigmatism is a recipe for later repercussions.

MY CATARACT SURGERY ACTION PLAN
I use a Rezoom on the first eye of every patient, because I think this IOL provides the best quality of vision. If the patient (1) responds well to the Rezoom implant and (2) is happy with the visual outcome, I will implant another Rezoom in the second eye. If the patient is 20/happy, I delay astigmatism correction until both eyes are done.

If the patient is not fully functional at all near tasks with their first eye, however, I implant a Restor in the second eye. The second implant is sequenced approximately 3 weeks apart from the first, allowing me to track the progress of the first eye. If the patient's quality of vision in the first eye is not acceptable to them because of residual astigmatism, I fix their astigmatism before I press on to the second eye. This plan has worked really well for me.

It is part of the overall surgical plan to treat patients for astigmatism; the goal is to relieve them of all astigmatism. Generally, I use one of three methods to correct astigmatism: laser treatment/surface ablation, limbal relaxing incisions (LRIs), or conductive keratoplasty (CK). I prefer to use a custom treatment profile any time it is an option, and I treat LASIK and other laser vision correction patients with this profile.

At my practice, 100% of patients undergoing laser vision correction receive treatment for their astigmatism, however, I only treat astigmatism in cataract patients who are receiving a multifocal IOL. Of the latter group, 25% will have some astigmatic correction as part of their custom treatment plan.

TREATMENT METHODS
I always rule out any subclinical cystoid macular edema before fine tuning a patient's postoperative outcome.

LRIs. These incisions may be performed at the time of surgery or as an independent procedure. If a patient's spherical equivalent is close to plano (ie, zero) then it is preferable to use LRIs, which neutrally affect the spherical equivalent.

If a patient's astigmatism is between 1.00 D and 2.00 D, however, I typically use LRIs at the time of surgery. If the astigmatism is more than 2.00 D, I may proceed with correction. I first inform the patient that it will most likely be a two-step procedure, where I will fine-tune their corneal shape after implantation.

LRIs are best used when the refractive astigmatism matches with the Pentacam (Oculus, Lynnwood, Washington) and the automated K-reading. All possible readings should show that the astigmatism is in the cornea; you do not want to treat lenticular astigmatism before cataract surgery, because you will actually induce corneal astigmatism. Furthermore, pay special attention to your preop measurements, because your refraction may sometimes be erroneous. Personally, I rely heavier on the Pentacam or topographic corneal astigmatism readings versus the patient's refraction. If the astigmatism and readings matched and LRIs were performed, the patient will need 2 months to heal before additional astigmatic treatment may be considered.

Laser treatments. If the astigmatism is visually influential, laser treatment—either LASIK or surface ablation—is an option. Laser vision correction should be performed as a custom treatment whenever possible, especially if the patient is hyperopic with postoperative astigmatism. I use the Visx S4 (Advanced Medical Optics) with custom cornea and iris registration whenever possible with reliable outcomes.

CK. Occasionally, you will need to treat a mildly hyperopic patient presenting with a small amount of astigmatism (ie, fewer than 2.00 D). In this case, my preference is to use CK. When using this astigmatic correction method, there will be a tiny myopic shift (ie, approximately 0.50 D). CK has a very safe profile and can be used 90º from LRIs; in the pseudophakic patient, they hold their effect for several years.

THE FUTURE
Astigmatic correction has come a long was since the advent of cataract and refractive surgery. I suggest to my cataract patients who want to be spectacle independent that they should first consider a multifocal implant and then get rid of the astigmatism by the methods mentioned above. I look forward to they day when toric multifocal IOLs are available. I believe that will be the next hot era in astigmatic correction.

H. L. "Rick" Milne, MD, is in private practice at The Eye Center, in Columbia, South Carolina. Dr. Milne states that he holds no financial interest in the products or companies mentioned. He may be reached at hmilne@aol.com or +1 803 256 0641.