When Plans for a Toric IOL Go Awry

Here's a backup plan to cover all contingencies.

BY NEAL NIRENBERG, M.D., F.A.C.S.

Modern cataract surgery has become not just a rehabilitative procedure but a refractive one as well. Expectations are high, and patients are willing to pay out of pocket for premium IOLs to meet them.

In 2005, the FDA approved Alcon's (Fort Worth, Texas) Acrysof toric lens implant. The FDA studies showed this lens to have remarkable stability, with an average of about 4° or less of rotation through the first 6 months of implantation. We have found this lens to be very precise, often correcting the patient's astigmatism to within 0.25 D or less.

One reason for the precision and stability of this lens is that it is placed in the capsular bag, with the anterior capsule covering the edge of the optic, allowing the bag to "shrink wrap it" into place. But what does one do when an unexpected complication occurs at surgery, such as a torn posterior capsule or torn zonules, that precludes the placement of a lens in the capsular bag? The Acrysof toric IOL is not designed for sulcus placement, and the patient has paid up front and is expecting correction of his or her astigmatism. Here is how we handle this situation in our practice.

Patient Education

The cornerstone of working with premium IOLs, and of ophthalmology in general, is a thorough examination by the physician and discussion of the findings with the patient. If the patient has a significant cataract along with a significant amount of corneal astigmatism, then astigmatism and the various means of correcting it at the time of cataract surgery are discussed with the patient.

We explain to the patient that most insurance carriers will cover cataract surgery with a lens implant for visual rehabilitation. We do not, however, put an emphasis on whether good postoperative vision is attained with or without glasses. Cataract surgery corrects cataracts, not astigmatism. Correcting astigmatism requires extra planning and surgery, which is why we charge for it, and the patient may elect to have it or not. We explain that in our practice, the charge to correct astigmatism is the same for either a toric IOL or limbal relaxing incisions (LRIs). The difference in cost is that the patient must pay the surgery center an additional amount if they elect to correct their astigmatism by use of a toric IOL, as these are premium lenses that cost the surgery center more money to acquire.

At this time we also explain that, although uncommon, there is always the chance that intraoperative complications could make the implantation of a toric IOL unadvisable. Should this occur, astigmatism would be corrected by LRIs and they would not be charged the additional amount for the toric IOL. A fee for astigmatism correction is collected prior to surgery and not refunded, as the astigmatism has been managed one way or the other. We have found that patients are fine with this explanation. After surgery, they are usually thrilled with their result and do not focus on how they got there.

Alcon's toric IOL calculator can be used to select a toric IOL and to plan LRIs.

That covers the preoperative exam, consult and administrative details.

Dealing With Complications

What do you actually do when there is a complication? It all begins with proper planning. Alcon's toric IOL calculator, which can be found online at http://www.acrysoftoriccalculator.com/calculator.aspx, has a helpful feature. By vector analysis, the calculator takes into account the amount of astigmatism induced by a surgeon's cataract incision and calculates the resultant corneal astigmatism. Not only can this feature be used to select a toric IOL, but to plan LRIs as well. (See Figure 1A and 1B). Let's say we are operating on a patient who has 2 D of corneal astigmatism at the corneal plane, steep axis 90°. We plan on implanting an SN60T5 toric IOL. Taking into account my incision at 135° and the 0.5 D of flattening it induces, the lens should result in zero residual astigmatism.

At this point I look at the Crossed-Cylinder Result (corneal plane) and see that due to my wound placement and the amount of astigmatism that I induce, the new amount of corneal astigmatism is 2.06 D, steeper on the 83° axis. Therefore, if I cannot implant a toric IOL, I would do paired LRIs to correct 2.06 D of corneal astigmatism on the 83° axis.

I draw this out on the printable page along with the location of wound placement and position of planned IOL axis. You should use an LRI nomogram that you are comfortable with. There are many out there ranging from the elegant but more complex nomogram devised by Louis D. "Skip" Nichamin, M.D., to the simple yet effective DONOGRAM devised by Eric Donnenfeld, M.D. I actually look at several and synthesize them to come up with a treatment plan I feel will work best.

Prepared for the OR

When I go to the OR, I am confident and loaded for bear. I have with me my first choice toric IOL, a three-piece backup posterior chamber IOL for sulcus placement and a third choice anterior chamber IOL, all with the appropriate lens power for their position in the eye. I have my printed treatment plan for a toric IOL or LRIs, my astigmatism axis markers, LRI markers and adjustable diamond blade. No matter what happens, the patient will get a lens implant and have their astigmatism managed.

We have found that setting things up this way has reduced our stress, the patient's stress, smoothed things at the front desk, eliminated refunds and most importantly has better helped us to meet our patients' visual expectations. OM

Neal Nirenberg, M.D., F.A.C.S., is in private practice at East Valley Ophthalmology in Mesa, Ariz. He can be reached at www.doctor-hill.com.