MAR 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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Page 144 of 210

E W RESIDENTS 142 March 2014 by Sundeep K. Kasi, MD, Michael Geske, MD, and Ayman Naseri, MD Review of "Correction of moderate corneal p eripheral corneal relaxing incisions (PCRI, also known as limbal relaxing incisions or LRIs). Several toric IOLs are commercially available that have been shown to be effective in the correction of postoperative astigma- tism. Similarly, the use of PCRIs has been shown to be effective for treat- ment of corneal astigmatism. At least two studies have com- p ared toric IOLs to monofocal IOLs with simultaneous PCRI. Mingo- Botin et al in 2010 conducted a prospective randomized trial in 40 eyes of 40 patients with three months of follow-up. 1 They found residual astigmatism to be signifi- cantly less in the toric IOL group (0.61 D vs. 1.32 D) with a slight r egression of effect of the PCRI from one to three months. They also noted trends toward better uncor- rected distance visual acuity (UDVA) in the toric IOL group with less need for spectacle correction for distance (15% vs. 45%) and better contrast sensitivity under mesopic condi- tions, but VF-14 satisfaction scores were comparable between the two groups. P oll et al retrospectively studied 192 patients with one month of follow-up. 2 In contrast to Mingo- Botin's study, the residual astigma- tism was comparable in both groups with 0.42 D in the toric IOL group and 0.46 D in the PCRI group; however, the toric IOL patients had higher preoperative keratometric astigmatism (2.10 D vs. 1.58 D). The U DVA was not different between the two groups except for patients with >2.25 D of preoperative astigmatism, where significantly more patients had UDVA of 20/40 or better in the toric IOL group compared to the PCRI group (87% vs. 53%). The current study compares the refractive outcomes and success in a stigmatic correction in patients un- dergoing cataract surgery with toric IOLs in one eye and standard mono- focal IOLs with simultaneous PCRI in the other eye with six months of follow-up. Study summary This study prospectively evaluated 60 eyes from 30 patients who under- went sequential phacoemulsification cataract surgery in both eyes from January 2009 to July 2009 with a toric intraocular lens implanted in one eye and a monofocal intraocular lens with peripheral corneal relaxing incisions in the fellow eye. Patients over the age of 40 with cataracts in both eyes and corneal cylinder be- tween 1 diopter and 2.5 diopters were included. Patients were ex- cluded for irregular astigmatism, forme fruste keratoconus, corneal scars, phacodonesis, pseudoexfolia- tion syndrome, traumatic cataract, and other pathology that may result in reduced capsular bag stability or postoperative visual performance. The primary outcome was vec- tor reduction in astigmatism at six months assessed by subjective refrac- tion. Secondary outcomes included uncorrected visual acuity, best corrected visual acuity, subgroup analysis of low versus moderate astigmatism, toric IOL axis stability, and regression of PCRI effect. Mean preoperative corneal astig- matism was similar in the toric IOL group (1.70 D) and PCRI group (1.57 D, p=0.24). At six months, the resid- ual refractive astigmatism was less in the toric IOL group (mean –0.62 D) compared to the PCRI group (mean –0.80 D, p=0.002). Accordingly, the m ean vector change was greater in the toric IOL group (1.74 D) com- pared to the PCRI group (1.27 D, p=0.042). Differences in uncorrected and best corrected visual acuity out- comes were not statistically signifi- cant. Mean absolute misalignment from the intended axis of the toric IOL axis was 4.4 degrees with an average of 2.5 degrees of axis shift f rom one hour postop to the six- month follow-up exam. In the PCRI group a regression of effect was noted, with the astigmatism vector found to increase between the one- month and six-month exam by an average of 0.38 D (p<0.001). Comments T his study is a well-designed prospective, randomized within-pa- tient comparison. It represents the largest randomized study to date comparing these two treatment op- tions. Its main contributions are a direct comparison of the surgical procedures in the same patients and a longer follow-up period than pre- vious studies. The data suggest that toric IOLs are more effective than PCRI for correction of astigmatism. Toric IOLs were shown to have a lower amount of postoperative resid- ual refractive error, with better re- fractive stability over a six-month follow-up period. There was also a trend toward improved uncorrected postoperative visual acuity in the toric IOL group, although this outcome did not reach statistical significance. These results mirror the prospective study by Mingo-Botin et al that found significantly better outcomes with toric IOL as com- pared to PCRI with regard to residual astigmatism. This is in contrast to the retrospective study by Poll et al that found no difference between the two groups. This work raises several impor- tant questions that may be answered in future studies. First, the present study utilized manual astigmatic keratotomy using the Donnenfeld nomogram. They not only found statistically significant residual astigmatism compared to toric IOLs, but also a regression effect similar to that found in the Mingo-Botin study. While the PCRI group showed regression effect, toric IOLs showed excellent alignment stability over time, with a mean rotation of only 2.5 degrees +/–1.8 degrees over six Ayman Naseri, MD, residency program director, University of California, San Francisco (UCSF) One of the best prospective studies to date comparing manual astigmatic keratotomy to toric IOLs appears in this month's JCRS. The UCSF residents review and discuss the paper below. –David F. Chang, MD, c hief medical editor E yeWorld journal club Correction of moderate corneal astigmatism during cataract surgery: Toric intraocular lens versus peripheral corneal relaxing incisions Nino Hirnschall, MD, Vinod Gangwani, MRCOphth, Alja Crnej, MD, John Koshy, MRCOphth, Vincenzo Maurino, MD, Oliver Findl, MD, MBA J Cataract Refract Surg (March) 2014; 40: 354–361 Purpose: To compare the astigmatism-reducing effect of a toric intraocular lens (IOL) and peripheral corneal relaxing incisions (PCRIs). Setting : Vienna Institute for Research in Ocular Surgery, a Karl Landsteiner Institute, Vienna, Austria. Design: Prospective masked bilateral randomized study. Methods: Cataract patients with a preoperative corneal astigmatism of 1.0 to 2.5 diopters (D) were included. All patients received a toric IOL in one eye and a nontoric IOL plus a PCRI in the other eye. Postoperative follow- up was at one hour, one month, and six months. The uncorrected distance visual acuity, corrected distance visual acuity, autorefraction (Topcon RM-8800), and subjective refraction were recorded. The IOL axis was assessed using retroillumination photographs. Results: The study enrolled 60 eyes of 30 patients. The mean astigmatism vector reduction was 1.74 D±0.64 (SD) in the toric IOL group and 1.27±0.76 D in the PCRI group; the difference was statistically significant (P=.042). The mean absolute rotation of the toric IOL was 2.5±1.8 degrees (maximum 6.3 degrees) in the first six postoperative months. Astigmatism increased in the PCRI group between the one-month and six-month follow-up (mean 0.38±0.27 D; maximum 1.00 D) (P<.001). Conclusion: Toric IOLs and PCRIs both reduced astigmatism; however, toric IOLs reduced astigmatism to a higher extent and they were more predictable. Financial disclosure: No author has a financial or proprietary interest in any material or method mentioned. Background The correction of postoperative astigmatism is a common goal for cataract surgeons whose patients seek spectacle independence. At the time of cataract surgery, corneal astigmatism is often treated with either placement of a toric intraocu- lar lens (toric IOL) or creation of toric intraocular lens versus peripheral 138-143 Residents_EW March 2014-DL2_Layout 1 3/6/14 4:16 PM Page 142

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