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Refractive Surgery | Mar 2014

Surgical Strategy in a High-Risk Eye

This patient experienced a hyperopic overcorrection after phakic IOL implantation that resolved without intervention.

One of the most important factors in successful refractive surgery is proper patient selection. Matching the surgical procedure to the indication is essential to ensure that each patient is satisfied with his or her outcome. This article presents a case report in which failure to consider several patient factors may have contributed to a dual refractive surprise after phakic IOL implantation. Luckily for the patient—and for myself—the condition resolved spontaneously. However, this case can serve as a lesson to consider all patient factors in an attempt to recognize eyes that are at risk for unusual outcomes in refractive surgery.

CASE PRESENTATION

A 37-year-old woman with highly myopic eyes expressed interest in refractive surgery. At the time of her initial visit, she explained that she wore hard contact lenses almost exclusively (OD, -9.00 D of sphere; OS, -9.00 D of sphere) but occassionally wore eye glasses (OD, -9.25 -0.25 X 117º; OS, -9.00 D of sphere).

Preoperatively, the patient’s autorefractometry measurement in her right and left eyes was -9.00 -0.75 X 22º and -8.50 -0.50 X 165º, respectively. Refractometry in mydriasis in her right and left eyes was -8.75 -0.25 X 50º and -8.00 -0.50 X 162º, respectively (Figures 1 through 4). With manifest refractions of -11.00 -0.75 X 22º and -9.50 -0.50 X 165º, respectively, both eyes achieved 1.00 Snellen decimal BCVA. Her cycloplegic refraction in her right and left eyes was -10.50 -0.75 X 220º and -9.50 -0.50 X 165º, respectively.

I used a phakic IOL calculator to calculate the correct IOL power for a target refraction around 0.00 D spherical equivalent (SE). The first surgery was planned for the eye with the higher refraction (right); the procedure in the second eye was scheduled for 2 days later. We ordered the Visian ICL V4c (STAAR Surgical) in powers of -12.50 D for her right eye and -10.50 D for her left.

FIRST AND SECOND SURGERIES

First Surgery The procedure was uneventful. On the first postoperative day, the patient had a residual refraction of 2.50 -1.25 X 14º, with a BCVA of 1.00. Because her UCVA was not optimal, she was dissatisfied with her results.

We decided to postpone surgery on her left eye. After 3 weeks, the patient’s measured refraction had improved, her degree of hyperopia in the operated eye was lower (1.00), and UCVA improved to 1.00. However, she reported some problems with near vision.

Second surgery. At this point, we carried out surgery on the patient’s left eye. On the first postoperative day, we again got a refractive outcome of mild hyperopia and astigmatism (1.75 -1.50 X 1º). On the second postoperative day, her UCVA was 0.90.

At a follow-up visit 2 months after surgery on her right eye and 1 month after surgery on her left, the patient had the following refractions and BCVAs: OD 0.50 -0.25 X 6º yielding 1.00 and OS -0.25 -0.50 X 9º yielding 1.00. The patient is happy with this outcome, although she reports that her distance vision is better in her right eye than in her left.

EXPLANATIONS

Initially, after the patient’s first surgery, I was concerned that I had made a mistake in calculating the preoperative measurements. For that reason, I was reluctant to implant the lens in her other eye using power calculations derived by the same methods—hence my decision to postpone surgery in the left eye. During this waiting period, the patient’s hyperopic refraction decreased and her UCVA improved. Therefore, we decided to proceed with the second surgery, using the originally calculated lens power.

There are several possible explanations for this hyperopic refractive surprise after surgery in this patient. First, we were dealing with a small eye. The patient’s anterior chamber depths, as measured by the Pentacam (Oculus; Figure 3), were OD 2.95 mm and OS 2.94 mm, which is on the lower limit for phakic IOL implantation in the posterior chamber. A second explanation may be that the position of the lens needed time to settle in the posterior chamber. Third, it is also possible that residual ophthalmic viscosurgical device in the operated eye disappeared more slowly than usual because of the eye’s small anatomic size.

CONCLUSION

Some of the more common reasons that refractive surprises occur after surgery include the limitations of our current biometry tools and IOL power calculation formulas and the unpredictability of effective lens position and corneal power due to previous refractive surgery.

Although we have at our disposal numerous technologies that can be useful for providing meaningful preoperative assessments, refractive surprises can still occur after surgery. It is important to remember that postoperative management depends on the patient, including his or her desire for correction and achievement of optimal visual outcomes.

Kristina Mikek, MD, is a Consultant of Ophthalmology and the Clinical Director of Morela Okulisti, Center for Eye Refractive Surgery, Ljubljana, Slovenia. Dr. Mikek states that she has no financial interest in the products or companies mentioned. She may be reached at tel: +38 641351339; fax: +38 615102342; e-mail: kmikek@morelaokulisti. si.

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