Toric Intraocular Lens Implantation for Correction of Astigmatism in Cataract Patients with Corneal Ectasia
A 57-year-old woman presented to our ophthalmology outpatient clinic with a gradually decreased visual acuity in both eyes because of posterior subcapsular cataract. On presentation, best spectacle-corrected visual acuity (BCVA) was 2/10 in the right eye and 4/10 in the left eye, with −3.75 −3.50 × 165° and −1.00 −3.50 × 6° subjective refraction in the right and left eye, respectively. Automated refractometry showed −4.75 −4.25 × 164° with K1 44.00 at 180° and K2 46.5 at 90° in the right eye and −10.75 −5.00 × 5° with K1 46.00 at 179° and K2 49.75 at 89° in the left eye. Corneal topography was performed using Orbscan (Bausch and Lomb Inc., Rochester, N.Y., USA) and revealed a central corneal thickness of 533 mm and an inferior temporal displacement of the thinnest point (512 mm), indicative of KC in both eyes (fig. ). Keratometry (K) values for the steep and flat axis were 47.25 D at 86° and 44.00 D at 176°, respectively, in the right eye, and 49.8 D at 84° and 45.6 D at 174°, respectively, in the left eye. It is important to mention that KC was stable in this patient for the last 2 years, which had been confirmed by previous corneal topographies. Biometry was performed with the IOL Master (Carl Zeiss Meditec, Jena, Germany) to calculate the IOL power for emmetropia using the Sanders-Retzlaff-Kraff theoretical (SRK/T) formula. A web-based toric IOL calculator program was used to determine the optimal cylinder power and alignment axis of the IOL (available at ) (fig. ). A standard phacoemulsification with toric IOL implantation (AcrySof SN60T7 Alcon, Ltd., Fort Worth, Tex., USA), with a spherical power of 19.5 D and a cylinder power of 4.50 D at the IOL plane aligned at 84°, was performed in the right eye. In the left eye, a toric IOL (AcrySof SN60T8) with a spherical power of 16.0 D and a cylinder power of 5.25 D at the IOL plane, being aligned at 89°, was used. Postoperatively, the BCVA was 9/10 with −0.50 sph in the right eye and 8/10 with −1.50 sph in the left eye, which remained stable at the 18-month and 24-month follow-up for the right and left eye, respectively. Corneal topography remained almost stable, with K values for the steep and flat axis of 47.5 D at 90° and 43.7 D at 180°, respectively, in the right eye, and 50.0 D at 94° and 46.0 D at 4°, respectively, in the left eye. The toric IOL alignment axis, as determined by slit-lamp biomicroscopy, remained at the same degrees at the end of the follow-up for both eyes (fig. ).