EyeWorld India September 2017 Issue

continued on page 38 by Stefanie Petrou Binder, MD EyeWorld Contributing Writer Cutting-edge technologies and better outcomes New toric IOL and trifocal IOL studies presented at the 21st Winter Meeting of the ESCRS demonstrate the benefits of cutting-edge technology T he AcrySof IQ toric IOL SN6AT3-9 (Alcon, Fort Worth, Texas) is highly effective in the treatment of preexistent corneal astigmatism in patients undergoing cataract surgery, according to the outcomes of a new Dutch study that was presented as a poster at the 21st Winter Meeting of the European Society of Cataract and Refractive Surgeons (ESCRS), in Maastricht, Holland. The study demonstrated residual astigmatism of roughly –0.5 D and postoperative misalign- ments of around 3 degrees. The 3-year toric IOL cohort study included 310 eyes that un- derwent cataract extraction and phacoemulsification followed by toric IOL implantation between June 2013 and June 2016. The study involved the VERION Image Guided System (Alcon) for toric IOL alignment, the AcrySof Toric Calculator (first generation, Alcon) for toric IOL power determination, and implantation of the AcrySof IQ toric IOL SN6AT3-9 in more than 95% of the study eyes. Preoperatively, the mean anterior corneal astigmatism was –2.45±1.16 D, and the mean posterior corneal astigmatism was –0.46±0.27 D. Sixty-one percent of eyes had with-the-rule astigmatism, and 25% had against-the-rule astigma- tism. Postoperatively, the mean residual refractive astigmatism was –0.57±0.56 D, and the mean uncorrected distance visual acuity was 0.12±0.18 logMAR. The mean postoperative misalignment was 3.3±3.7 degrees. “A general overcorrection was seen in with-the-rule eyes, which might be explained with the use of a first generation toric calculator neglecting the posterior corneal astigmatism,” said Valentijn We- bers, MD , University Eye Clinic of Maastricht, the first author of the study, who presented his work. “Secondary treatments like IOL re- positioning, additional LASEK, and IOL exchanges were required in a small percentage of cases.” Complications and management Dr. Webers reported that 276 of the study eyes (89%) had a misalign- ment of less than 5 degrees, 20 eyes (6%) were misaligned by 5–10 degrees, and 14 eyes (5%) by more than 10 degrees. Only 13 eyes (4%) underwent a secondary surgical treatment: realignment in seven eyes (2%), IOL exchange in four eyes (1%), and laser touch-up in two eyes (1%). Of the 189 with-the-rule astigmatism eyes, 43.3% resulted in overcorrections of more than 0.5 D, and 11.1% resulted in over- corrections of more than 1.0 D. Undercorrections of more than 0.5 D were seen in 0.5% and under- corrections of more than 1.0 D in none of the study eyes. “There was more overcorrec- tion than undercorrection for all toric IOL powers, with the highest overcorrections occurring in eyes receiving the highest toric IOL powers. Also, less astigmatism was noted postoperatively at 0.50±0.45 D, compared to preoperatively at 2.56±1.09 D ( P <0.001). The mean correction index, calculated using vector analysis, was 1.22±0.20. The correction index is the ratio between the aimed correction of the preexistent astigmatism and the achieved correction. Ideally, the correction index is 1.0. A ratio higher than 1.0 reflects an over- correction, whereas a ratio below 1.0 reflects an undercorrection. Overcorrection was associated with a flipping of the astigmatism axis postoperatively,” Dr. Webers said. In the 79 eyes with against-the- rule astigmatism, overcorrections of more than 0.5 D were noted in 7.6% of eyes and overcorrections of more than 1.0 D in 2.5% of these eyes. Only 2% of against-the-rule eyes had undercorrections of more than 0.5 D, and none were overcor- rected more than 1.0 D. “There was less overcorrec- tion in the against-the-rule group as compared to the with-the-rule group, with the highest percentage of overcorrection seen in SN6AT9 eyes. Less astigmatism was noted postoperatively at 0.62±0.68 D ver- sus preoperatively at 2.29±0.97 D ( P <0.001) in these eyes. The mean correction index was 1.01±0.19. In eyes with no overcorrection, the astigmatism axis did not flip,” he said. Technology and biometry are key Another poster presentation at the meeting evaluated the visual and optical performance of eyes implanted with the trifocal IOL AT LISA tri 839MP (Carl Zeiss Meditec, Jena, Germany). According to Matteo Piovel- la, MD , medical director, Centro Microchirurgia Ambulatoriale, Monza, Italy, who presented the study, the refractive surgeon needs The optical zone of the AT LISA tri toric 939MP. It has fewer rings on the IOL optic surface for reduced potential visual disturbances and improved night vision. The near addition is +3.33 D for comfortable reading distance. The intermediate addition is +1.66 D, which does not compromise near or distance vision. Source: Matteo Piovella, MD 37 EWAP CATARACT/IOL September 2017