ARTICLE
Multifocal toric intraocular lenses versus multifocal intraocular lenses combined with peripheral corneal relaxing incisions to correct moderate astigmatism Vinod Gangwani, MRCOphth, FRCS, Nino Hirnschall, MD, PhD, Oliver Findl, MD, MBA, Vincenzo Maurino, MD
PURPOSE: To compare the outcomes of multifocal toric intraocular lens (IOL) implantation and standard nontoric multifocal IOL implantation combined with peripheral corneal relaxing incisions (PCRIs) in patients with moderate preexisting corneal astigmatism. SETTING: Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. DESIGN: Prospective randomized controlled trial. METHODS: Patients with visually significant cataract in both eyes who desired spectacle independence and had corneal astigmatism (1.00 to 2.50 diopters [D]) had multifocal toric IOL implantation in 1 eye and a nontoric multifocal IOL combined with PCRIs (Donnenfeld nomogram) in the contralateral eye. Outcome measures were visual acuity, astigmatic vector reduction, digital toric IOL axis determination, spectacle need, and patient satisfaction. RESULTS: Thirty patients were enrolled. Three months postoperatively, the mean residual refractive astigmatism was 0.45 D G 0.49 (SD) in the toric IOL group and 0.72 G 0.61 D in the PCRI group. The mean uncorrected distance visual acuity was 0.10 G 0.14 in the toric IOL group and 0.15 G 0.14 in the PCRI group and the mean uncorrected near visual acuity, 0.43 G 0.11 and 0.39 G 0.10, respectively. The mean absolute misalignment from the intended axis was 2.52 G 1.97 degrees. The rotation was within G3 degrees in 90.9% of all cases and within G6 degrees in all cases. On the questionnaire, 52.9% of all patients said they required spectacles only when reading for a long time. CONCLUSION: Although refractive astigmatism decreased in both groups, multifocal toric IOL implantation was predictable with good rotational stability. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2014; 40:1625–1632 Q 2014 ASCRS and ESCRS
Modern cataract surgery is no longer simply extraction of the lens content and implantation of a spherical intraocular lens (IOL). Surgeons can now select from IOLs with more complex optics, and these IOLs may better meet patients' visual expectations in terms of spectacle independence. The number of patients expecting to function at all distances without spectacles after uneventful cataract surgery has steadily increased in the past few years. However, multifocal IOLs have been shown to have poor performance in patients with moderate to high degrees of residual postoperative astigmatism.1,2 Managing Q 2014 ASCRS and ESCRS Published by Elsevier Inc.
preexisting corneal astigmatism at the time of cataract surgery is integral to achieving optimum refractive outcomes. It is estimated that approximately 40% of patients having cataract surgery have astigmatism of more than 1.00 diopter (D).3 Different methods are used to reduce preoperative corneal astigmatism during cataract surgery. This study compared 2 of these methods in eyes with moderate astigmatism. With multifocal toric IOLs, the combination of multifocal and toric optical components allows the potential benefit of reduced spectacle dependence 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2014.01.037
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to be extended to patients with significant corneal astigmatism. This would prevent them from requiring additional procedures, such as peripheral corneal relaxing incisions (PCRIs),4 opposite clear corneal incisions (CCIs), or even refractive laser surgery, during or after cataract surgery.5,6 The only drawback is the added extra cost of multifocal toric IOLs. However, although less expensive alternatives, such as limbal relaxing incisions, have been used for decades to reduce astigmatism during cataract surgery,7,8 they appear to be relatively unpredictable and may lead to need for further enhancement surgery to achieve full correction.4 The aim of this study was to compare the outcomes of multifocal toric IOL implantation with those of standard nontoric multifocal IOL implantation combined with PCRIs in patients with moderate preexisting corneal astigmatism. PATIENTS AND METHODS This randomized bilateral patient-masked and examinermasked study included patients who were scheduled for cataract surgery in both eyes and who desired spectacle independence. All research and measurements followed the tenets of Declaration of Helsinki, and the local ethics committee approved the study. All patients provided informed consent before the procedure. Inclusion criteria were bilateral corneal astigmatism between 1.0 and 2.5 D on automated keratometry performed with partial coherence interferometry (PCI) (IOLMaster, software version 5.x, Carl Zeiss Meditec AG); visually significant cataract in both eyes; and age of 40 years or older. Exclusion criteria were irregular astigmatism or forme fruste keratoconus on Scheimpflug corneal tomography (Pentacam HR, Oculus Optikger€ate GmbH), corneal scars, phacodonesis, pseudoexfoliation syndrome, traumatic cataract, and other ophthalmic copathology that could
Submitted: September 10, 2013. Final revision submitted: December 29, 2013. Accepted: January 13, 2014. From Moorfields Eye Hospital NHS Foundation Trust (Gangwani, Hirnschall, Findl, Maurino), London, United Kingdom; the Department of Ophthalmology (Hirnschall), Vienna Institute for Research in Ocular Surgery–A Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria. Supported by the Department of Health through an award made by the National Institute for Health Research to Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology for a Specialist Biomedical Research Centre for Ophthalmology. The views expressed in this publication are those of the authors and not necessarily those of the Department of Health. Also supported by an unrestricted grant from Rayner Surgical, United Kingdom. Corresponding author: Vincenzo Maurino, MD, Moorfields Eye Hospital, City Road, London EC1V 2PD, United Kingdom. E-mail: [email protected].
have an impact on capsular bag stability or postoperative visual function. All patients were recruited from December 2009 to December 2010. Each patient received a multifocal toric IOL in 1 eye and a nontoric multifocal version of the same IOL platform (M-Flex, Rayner Intraocular Lenses, Ltd.) combined with 1 or 2 PCRIs in the contralateral eye to allow for intraindividual comparison. The second eye was operated on within 4 weeks of the first surgery and received the alternate treatment. Group allocation of the first eye was random. Randomization was performed using a computer-based system by a person otherwise not involved in the trial. The patient and examiners were masked to the group allocation, and the surgeon was masked to allocation until the time of IOL implantation. The target postoperative refraction was emmetropia to slight hyperopia (0.00 to 0.25 D). One of 2 experienced surgeons (O.F., V.M.) performed the operations, with the same surgeon operating on both eyes of a patient.
Preoperative Marking and Surgical Technique Preoperatively, the horizontal meridian was marked with the patient sitting at the slitlamp and the patient's head straight in the chinrest. The slit beam was positioned in the retroillumination position and the slit oriented horizontally, centered on the pupil. Small superficial incisions were made at the periphery of the cornea into the epithelium using an insulin needle (30-gauge) at the 3 o’clock and 9 o’clock positions as well as at the 12 o’clock meridian with the slit in the vertical position. Care was taken to center the slit beam on the center of the pupil for alignment.9 Color was added to the 3 incisions with a sterile marking pen for easier recognition intraoperatively. Finally, the correct position markings were verified at the slitlamp. If a marking was slightly off the intended meridian, this was recorded on the biometry report form to aid the surgeon when positioning the corneal marker intraoperatively. Surgery was performed using topical anesthesia in both groups. After the Mendez-style corneal marking ring was aligned to the 3 preoperative markings, blue pen dots were made on the planned meridian. Incisions were made as per recommendation in each group. This was followed by injection of an ophthalmic viscosurgical device (OVD). Next, a capsulorhexis was created and phacoemulsification and irrigation/aspiration (I/A) of cortical material were performed. Then, a cohesive OVD (sodium hyaluronate 1.0% [Provisc]) was injected into the capsular bag and the IOL implanted. All patients received an intracameral injection of 1 mg/ 0.1 mL cefuroxime at the end of surgery. Postoperatively, patients received dexamethasone eyedrops 0.1% 4 times a day, which were tapered over 4 weeks, and chloramphenicol eyedrops for 3 weeks.
Toric Intraocular Lens Group The Mflex-T multifocal toric IOL is hydrophilic acrylic and injectable. It is based on multizone refractive aspheric optic technology, with 4 or 5 annular zones (depending on IOL base power) providing C3.00 D or C4.00 D of additional refractive power at the IOL plane (equivalent to C2.25 D or C3.00 D at the spectacle plane). At present, this IOL is manufactured as model 588F and model 638F, which have a 5.75 mm optic or a 6.25 mm optic, respectively. The standard power range is C14.00 D to C32.00 D in 0.50 D increments for sphere and 10.00 D to 6.00 D in 0.50 D increments
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for cylinder. The model selection was made automatically by the manufacturer so the largest possible diameter optic was supplied for any combination of sphere, cylinder, and injector nozzle. Model 638F is designed for low-power and medium-power IOLs, and model 588F is designed for higher power IOLs. Power calculation and the orientation for the toric IOLs were calculated using an online software program from the IOL manufacturer.A Preoperative keratometry and biometry data, incision location, and the surgeon's estimated corneal surgically induced astigmatism of 0.05 D (incision size 2.65 mm) were used to determine the appropriate toric IOL model, spherical equivalent (SE) IOL power, and meridian of placement in the eye. The SRK/T formula10 was used for spherical IOL power calculation when axial length (AL) was 22.0 mm or longer and the Hoffer Q11 formula when the AL was less than 22.0 mm. The toric IOL was implanted in the capsular bag using the injector provided with the IOL. The steep axes markings of the toric IOL were then positioned approximately 20 degrees counterclockwise from the planned meridian of placement by rotating the IOL, after which the OVD was aspirated thoroughly using a bimanual I/A set. Care was taken to completely remove the OVD from behind the IOL by slightly displacing and tilting the IOL and reaching behind the optic with the aspiration cannula. Thereafter, the toric IOL was rotated further clockwise until, in the surgeons' opinion, perfect alignment with the corneal marks was achieved. A final check was made after the anterior chamber was filled and the incisions were hydrated.
Peripheral Corneal Relaxing Incision Group Calculations for the PCRI group were performed with the Donnenfeld nomogram using an online calculator.B A CCI (2.65 mm) on the steep meridian was preferred and combined with a single opposite PCRI. In cases in which creating a CCI on the steep meridian was awkward, such as superonasal incisions in deep-set eyes, a temporal incision combined with 2 PCRIs was created. One surgeon (V.M.) performed all PCRIs at the start of surgery, while another surgeon (O.F.) performed all PCRIs at the end of surgery. Both surgeons used an identical 600 mm guided steel blade (Micro Feather ophthalmic scalpel with aluminum handle, No: 7360G, Feather Safety Razor Co. Ltd.). The depth of the PCRIs was 600 mm, and the length was as per the nomogram.
Patient Assessment Scheimpflug corneal tomography was performed preoperatively in all eyes to rule out irregular astigmatism and ensure the eye had normal corneal thickness. Surgically induced astigmatism of 0.50 D was taken into account during the calculations in both groups. Patients were examined 1 month and 3 months postoperatively. Monocular uncorrected distance visual acuity (UDVA) using distance Early Treatment Diabetic Retinopathy Study (ETDRS) charts (Precision Vision), corrected distance visual acuity (CDVA), autorefraction (Topcon RM-8800), and subjective refraction using the Jackson cross-cylinder method and trial frames were recorded for all patients. Near vision was tested using the near-vision ETDRS chart at 40 cm. Glare testing was performed using a straylight meter (C-Quant, Oculus Optikger€ ate GmbH), and contrast sensitivity was measured using
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Pelli-Robson charts (Precision Vision) at 1 m. Patient satisfaction was also recorded using a simple questionnaire. This questionnaire asked whether the patient experienced glare or halos and if so, whether these symptoms bothered the patient. Patients were also asked whether they thought that 1 of their eyes had better vision than the fellow eye. The IOL toric axis was assessed using retroillumination photographs performed 1 hour, 1 month, and 3 months after surgery. Details of the photographic technique have been described.12 For rotational stability analysis, Keynote software (version 5.0.2, Apple, Inc.) was used. All retroillumination images were imported into the software system. Images were not analyzed if the markings on the IOL were not visible because of a small pupil. To avoid observer bias due to knowledge of the IOL orientation on the previous follow-up photograph of a patient, all images were imported in random to ensure that the images of each patient were not analyzed consecutively. Two, thin (0.25 pixel) straight lines were adjusted to the marking on the IOL after magnifying the images. Each line touched the toric marking on the IOL on each side so that as a result, the 2 lines were parallel to the marking between the lines. The axes of both lines were entered into an Excel spreadsheet (Microsoft Corp.), and the mean value of both lines was used for further statistical analysis.
Statistical Analysis Astigmatism vector analysis was performed using Thibos and Horner's power vector notation.13 For statistical analysis, Excel 2011 for Mac with a Statplus:mac version 5.8.3.8 plugin (Analystsoft) and an Xlstat 2012 plugin (Addinsoft) was used. Descriptive data are shown as the mean G standard deviation. To compare measurements of the same eye at different timepoints, the analysis of variance and analysis of covariance for repeated measurements was used, if not stated otherwise. In all other cases, the test used is shown next to the P value. In general, a P value below 0.05 was considered significant (with a power of more than 80%).
RESULTS This study comprised 58 eyes of 29 patients. Three patients were lost to follow-up, 1 due to general health problems and 2 due to noncompliance, and were excluded from analysis. The mean age of the remaining patients was 74.8 years G 4.6 (SD); the male-tofemale distribution was 13:14. Astigmatism The mean preoperative corneal astigmatism measured with the PCI device was 1.82 G 0.45 D (maximum 2.58 D) in the toric IOL group and 1.67 G 0.58 D (maximum 2.57 D) in the PCRI group. The difference between the toric IOL group and the PCRI group was not statistically significant (P Z .29, Wilcoxon signed-rank test). Therefore, it was not necessary to adjust the postoperative astigmatism outcome to the baseline values for further analysis. The mean residual refractive astigmatism 3 months
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Figure 1. Vector differences between the preoperative keratometry and the astigmatism in subjective refraction at the 3-month postoperative follow-up in diopters (PCRI Z peripheral corneal relaxing incision).
after cataract surgery assessed by subjective refraction was 0.45 G 0.49 D (maximum 1.50 D) in the toric IOL group and 0.72 G 0.61 D (maximum 2.00 D) in the PCRI group. The difference between the 2 groups was statistically significant (P Z .046, Wilcoxon signed-rank test). Figure 1 shows the distribution of the postoperative residual astigmatism. The mean astigmatism vector difference from the target astigmatism was 0.22 G 0.25 D (maximum 0.75 D) in the toric IOL group and 0.36 G 0.30 D (maximum 1.00 D) in the PCRI group. This difference was not statistically significant (P Z .314). Concerning astigmatism vector reduction, measured as corneal astigmatism in keratometry with the PCI device preoperatively and using the subjective refractive astigmatism refraction 3 months postoperatively, the mean absolute vector difference (mean absolute error) was 1.76 G 0.47 D in the toric IOL group and 1.56 G 0.63 D in the PCRI
group. The difference between the 2 groups was statistically significant (P Z .042, Wilcoxon signedrank test). Visual Quality The mean B-vector distance (SE C J0 C J45) was 0.58 G 0.29 D in the toric IOL group and 0.62 G 0.40 D in the PCRI group. The difference was not statistically significant. Table 1 shows the results for all other visual quality parameters. Toric Intraocular Lens Rotation The mean absolute misalignment from the intended positioning axis of toric IOLs at the 3-month follow-up was 2.52 G 1.97 degrees (Figure 2, top). The maximum misalignment was 6.0 degrees. The mean absolute rotation in the toric IOL group between the 1-hour to 3-month postoperative photographs was 1.68 G 1.18
Table 1. Postoperative visual acuity and contrast sensitivity. Group/Parameter Toric IOL (mean G SD) PCRI (mean G SD) P value
LogMAR UDVA
LogMAR UNVA
Photopic CS (Log Units)
Mesopic CS (Log Units)
Log(s)
0.10 G 0.14 0.15 G 0.14 .120
0.43 G 0.11 0.39 G 0.10 .078
1.56 G 0.26 1.51 G 0.22 .243
1.29 G 0.25 1.16 G 0.32 .143
1.18 G 0.18 1.14 G 0.20 .14
CS Z contrast sensitivity; Log(s) Z log (straylight parameter); PCRI Z peripheral corneal relaxing incision; UDVAZ uncorrected distance visual acuity; UNVA Z uncorrected near visual acuity
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Figure 2. Misalignment and rotation of toric multifocal IOLs in degrees (amounts on the y-axes).
degrees (Figure 2, bottom). In 24 cases (90.9%), the rotation was within G3 degrees; in all cases it was within G6 degrees. In 14 cases (54.5%), the rotation was within G1.5 degrees. In 12 cases (45.5%), the toric IOL rotated more than 1.5 degrees clockwise; in no case did it rotate more than 1.5 degrees counterclockwise. Questionnaire On the questionnaire, all patients reported that they were not wearing spectacles most of the time, although 9 patients (52.9%) needed spectacles when reading for a long time. Seven patients (41%) reported glare and 6 (35%) reported halos; no patient reported being bothered by these phenomena. One patient identified the eye with a toric IOL as the better eye and 1 patient the eye with the PCRI. None of these findings was statistically significant. DISCUSSION Multifocal toric IOL implantation and performing PCRIs reduced preoperative low to moderate corneal
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astigmatism. Comparison with previous studies is difficult because, to our knowledge, this is the first study evaluating an acrylic multifocal toric IOL with a hydrophobic surface and an open-loop haptic design. There are 3 multifocal toric IOLs on the market; however, they differ in design (Acri.Lisa toric, Carl Zeiss Meditec AG, and Lentis Mplus toric, Oculentis GmbH) or material (Acrysof IQ Restor toric, Alcon Laboratories, Inc., and Tecnis multifocal toric, Abbott Medical Optics, Inc.).14 In our study, the astigmatism was reduced in both groups but slightly more so in the toric IOL group. These findings are similar to those by Mingo-Botín et al.15 Although their study was not bilateral and they used a different toric IOL, the studies are comparable because they included a similar range of preoperative corneal astigmatism and performed the same astigmatism vector analysis. Residual refractive astigmatism was less than 1.00 D in 90% of eyes in the Botín et al. study (96% in our study) in the toric IOL group and in 40% of eyes (84% in our study) in the PCRI group. This large difference in the PCRI group between the studies could be explained by the fact that different PCRI nomograms were used or, more likely, that the preoperative corneal astigmatism was lower in our study. These findings are contrary to observations by Poll et al.,16 who did not observe a significant difference between the 2 astigmatism-reducing methods. Their study was not bilateral and not prospective. Furthermore, there was a significant difference between the toric IOL group and the PCRI group, and this difference was not adequately taken into account in the postoperative analysis. In addition, their study mainly focused on the difference between preoperative and postoperative astigmatism; however, no significance levels and little explanation for the vector analysis were given. Although no studies of residual astigmatism with the IOL used in this study are available, overall results are similar to those reported for other toric IOLs. Very similar results were reported by Holland et al.17 for the Acrysof toric IOL (53% %0.50 D; 88% %1.00 D); others reported slightly better results.18–20 Residual astigmatism was reported to be higher for the Staar IOL21 (Staar Surgical) (49% %0.50 D; 78% %1.0 D) and for the Microsil toric IOL (Humanoptics AG) 22 (25% %0.50 D; 50% %1.00 D). Astigmatism vector reduction 3 months postoperatively in the PCRI group in this study was similar to findings by Kaufmann et al.23 (1.10 D after 6 months) and Budak24 (1.47 D after 1 month). Prediction of residual astigmatism remains difficult and depends on many factors, such as inaccurate preoperative keratometry,25,26 not taking the
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posterior surface of the cornea into account,27 inaccurate preoperative marking,9 potential mislabeling of the toric IOL, the impact of an unexpectedly deep or flat anterior chamber depth postoperatively,28 inaccurate placement of the IOL during surgery, and postoperative decentration and/or tilt or rotation of the IOL. All these can decrease the predictability of the residual refractive astigmatism. Furthermore, assessing subjective refraction has been shown to be inaccurate.26 The UDVA findings in a study by Cez on Prieto and Bautista29 were similar to those with the multifocal nontoric design of the same IOL when the preoperative astigmatism was below 1.00 D; however, their uncorrected near visual acuity (UNVA) results were slightly better. Visser et al.30 studied the AT Lisa toric multifocal toric IOL (Carl Zeiss Meditec AG), which is diffractive. They found slightly better UDVA and UNVA than in our study. In our study, there was no significant difference between the UDVA in the 2 groups, although there was a trend for slightly better visual acuity in the toric group. In a similar study by Mingo-Botín et al.,15 the UDVA was significantly better in the toric group. In 2 other studies, the UDVA with the same IOLs as in our study was observed. Whereas Entabi et al.31 observed that 18% of patients had a UDVA of better than 20/25, Stewart and McAlister32 observed that 36% of all patients had an UDVA of better than 20/ 25. However, UDVA depends on many factors and is, therefore, a weak parameter for IOL evaluation purposes. In our opinion, it would be more interesting to show the difference between the CDVA and the UDVA to assess the effects of astigmatism-reducing methods. The rotational stability of the toric IOL we used in our study was good and slightly better than in other studies of the same toric IOL.31,32 Other toric IOLs, such as open-loop acrylic models (Acrysof toric), showed similar to slightly worse rotational stability.12,17,33,34 Worse rotational stability was observed for Z-haptic toric IOLs (Microsil 6116TU, Humanoptics AG).22,35 Hydrophilic acrylic platehaptic IOLs (Acri-Comfort, Carl Zeiss Meditec AG) also showed good rotational stability of 2 degrees35 to 2.6 degrees (Acri.Smart 46S, Carl Zeiss Meditec AG),36 similar to that in our study. In our study, counterclockwise rotation occurred but there was no clockwise rotation of more than 1.5 degrees. This may be because the haptics of the IOL we used are slightly more bulky than those of other toric IOL models. These findings are contrary to those with open-loop haptics. A higher proportion of IOLs with open-loop haptics showed clockwise rotation, possibly because of the haptic compression resulting
from capsule collapse and fibrosis.12 However, it should be taken into account that measurements of the rotational stability of toric IOLs are not completely accurate. The measurement method used in this study has been shown to be highly reproducible12 and similar to more technical analyzing methods.37–39 However, none of these methods is free of errors and small deviations may be the result of cyclorotation of the eye during standardized photography.40 In this study, approximately 40% of all patients reported glare and one third reported experienced halos; however, none of the patients were bothered by these phenomena. The percentage of glare and halos was lower than that for the same nontoric IOL design but in patients with low astigmatism.29 In our study, none of the patients reported requiring spectacles all the time, although 52.9% said they needed spectacles when reading for a long time. Toric IOLs lack the side effects of PCRIs, such as transient foreign-body sensation shortly after surgery, decreased corneal sensitivity, risk for corneal infection, and potentially more pronounced dry-eye syndrome after surgery. Toric IOLs, however, increase the costs of surgery and in most countries, they are not covered by insurance companies or the public health system. To summarize, both toric IOLs and PCRIs reduced astigmatism. However, toric IOLs were found to have several advantages over PCRIs. With the toric IOLs, astigmatism reduction was more pronounced, the interpatient deviation in postoperative astigmatism was smaller; therefore, the toric IOLs were more predictable. In addition, there was no regression effect with the toric IOLs.
WHAT WAS KNOWN Toric IOLs and PCRIs successfully reduce preoperative corneal astigmatism. Modern toric IOLs show a good rotational stability. WHAT THIS PAPER ADDS Astigmatism was reduced in both groups, but predictability was slightly higher in the toric IOL group. The rotational stability of the IOL investigated was good.
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a case series of eyes with cataracts and large amounts of corneal astigmatism. J Refract Surg 2012; 28:302–304 Ahmed IIK, Rocha G, Slomovic AR, Climenhaga H, Gohill J, goire A, Ma J, for the Canadian Toric Study Group. Visual Gre function and patient experience after bilateral implantation of toric intraocular lenses. J Cataract Refract Surg 2012; 36:609–616 Ruhswurm I, Scholz U, Zehetmayer M, Hanselmayer G, Vass C, Skorpik C. Astigmatism correction with a foldable toric intraocular lens in cataract patients. J Cataract Refract Surg 2000; 26:1022–1027 €ber L. Ausgleich des kornealen Dick HB, Krummenauer F, Tro Astigmatismus mit torischer Intraokularlinse: Ergebnisse der Multicenterstudie [Compensation of corneal astigmatism with toric intraocular lens: results of a multicentre study]. Klin Monatsbl Augenheilkd 2006; 223:593–608 Kaufmann C, Peter J, Ooi K, Phipps S, Cooper P, Goggin M; for the Queen Elizabeth Astigmatism Study Group. Limbal relaxing incisions versus on-axis incisions to reduce corneal astigmatism at the time of cataract surgery. J Cataract Refract Surg 2005; 31:2261–2265 Budak K, Friedman NJ, Koch DD. Limbal relaxing incisions with cataract surgery. J Cataract Refract Surg 1998; 24:503–508 Savini G, Carbonelli M, Sbreglia A, Barboni P, Deluigi G, Hoffer KJ. Comparison of anterior segment measurements by 3 Scheimpflug tomographers and 1 Placido corneal topographer. J Cataract Refract Surg 2011; 37:1679–1685 Norrby S. Sources of error in intraocular lens power calculation. J Cataract Refract Surg 2008; 34:368–376 Belin MW, Khachikian SS. An introduction to understanding elevation-based topography: how elevation data are displayed – a review. Clin Exp Ophthalmol 2009; 37:14–29. Available at: http://onlinelibrary.wiley.com/doi/10.1111/j.1442-9071.2008. 01821.x/pdf. Accessed May 20, 2014 Goggin M, Moore S, Esterman A. Outcome of toric intraocular lens implantation after adjusting for anterior chamber depth and intraocular lens sphere equivalent power effects. Arch Ophthalmol 2011; 129:998–1003; correction 1494. Available at: http://archopht.jamanetwork.com/data/Journals/OPHTH/22540/ ecs05115_998_1003.pdf. Correction available at: http:// archopht.jamanetwork.com/data/Journals/OPHTH/22547/ecx15 011_1494_1494.pdf. Accessed May 10, 2014 n Prieto J, Bautista MJ. Visual outcomes after implantation Cezo of a refractive multifocal intraocular lens with a C3.00 D addition. J Cataract Refract Surg 2010; 36:1508–1516 Visser N, Nuijts RMMA, de Vries NE, Bauer NJC. Visual outcomes and patient satisfaction after cataract surgery with toric multifocal intraocular lens implantation. J Cataract Refract Surg 2011; 37:2034–2042 Entabi M, Harman F, Lee N, Bloom PA. Injectable 1-piece hydrophilic acrylic toric intraocular lens for cataract surgery: efficacy and stability. J Cataract Refract Surg 2011; 37:235–240 Stewart CM, McAlister JC. Comparison of grafted and nongrafted patients with corneal astigmatism undergoing cataract extraction with a toric intraocular lens implant. Clin Exp Ophthalmol 2010; 38:747–757 Chang DF. Comparative rotational stability of single-piece openloop acrylic and plate-haptic silicone toric intraocular lenses. J Cataract Refract Surg 2008; 34:1842–1847 Kwartz J, Edwards K. Evaluation of the long-term rotational stability of single-piece, acrylic intraocular lenses. Br J Ophthalmol 2010; 94:1003–1006 De Silva DJ, Ramkissoon YD, Bloom PA. Evaluation of a toric intraocular lens with a Z-haptic. J Cataract Refract Surg 2006; 32:1492–1498
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36. Prinz A, Neumayer T, Buehl W, Vock L, Menapace R, Findl O, Georgopoulos M. Rotational stability and posterior capsule opacification of a plate-haptic and an open-loop-haptic intraocular lens. J Cataract Refract Surg 2011; 37:251–257 37. Nguyen TM, Miller KM. Digital overlay technique for documenting toric intraocular lens axis orientation. J Cataract Refract Surg 2000; 26:1496–1504 38. Rozema JJ, Gobin L, Verbruggen K, Tassignon M-J. Changes in rotation after implantation of a bag-in-the-lens intraocular lens. J Cataract Refract Surg 2009; 35:1385–1388 € tzner A, Becker R, Pavlovic S. 39. Weinand F, Jung A, Stein A, Pfu Rotational stability of a single-piece hydrophobic acrylic intraocular lens: new method for high-precision rotation control. J Cataract Refract Surg 2007; 33:800–803 40. Viestenz A, Seitz B, Langenbucher A. Evaluating the eye’s rotational stability during standard photography; effect on determining the axial orientation of toric intraocular lenses. J Cataract Refract Surg 2005; 31:557–561
OTHER CITED MATERIAL
A. Rayner Intraocular Lenses, Ltd. RayflexÒ. Toric Calculator and On-line Ordering System. Available at: http://www.rayner.com/ raytrace/. Accessed May 10, 2014 B. Abbott Laboratories, Inc. Welcome to the AMO LRI calculator software. Available at: http://www.lricalculator.com. Accessed May 10, 2014
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First author: Vinod Gangwani, MRCOphth, FRCS Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
Multifocal toric intraocular lenses versus multifocal intraocular lenses combined with peripheral corneal relaxing incisions to correct moderate astigmatism Vinod Gangwani, MRCOphth, FRCS, Nino Hirnschall, MD, PhD, Oliver Findl, MD, MBA, Vincenzo Maurino, MD
PURPOSE: To compare the outcomes of multifocal toric intraocular lens (IOL) implantation and standard nontoric multifocal IOL implantation combined with peripheral corneal relaxing incisions (PCRIs) in patients with moderate preexisting corneal astigmatism. SETTING: Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. DESIGN: Prospective randomized controlled trial. METHODS: Patients with visually significant cataract in both eyes who desired spectacle independence and had corneal astigmatism (1.00 to 2.50 diopters [D]) had multifocal toric IOL implantation in 1 eye and a nontoric multifocal IOL combined with PCRIs (Donnenfeld nomogram) in the contralateral eye. Outcome measures were visual acuity, astigmatic vector reduction, digital toric IOL axis determination, spectacle need, and patient satisfaction. RESULTS: Thirty patients were enrolled. Three months postoperatively, the mean residual refractive astigmatism was 0.45 D G 0.49 (SD) in the toric IOL group and 0.72 G 0.61 D in the PCRI group. The mean uncorrected distance visual acuity was 0.10 G 0.14 in the toric IOL group and 0.15 G 0.14 in the PCRI group and the mean uncorrected near visual acuity, 0.43 G 0.11 and 0.39 G 0.10, respectively. The mean absolute misalignment from the intended axis was 2.52 G 1.97 degrees. The rotation was within G3 degrees in 90.9% of all cases and within G6 degrees in all cases. On the questionnaire, 52.9% of all patients said they required spectacles only when reading for a long time. CONCLUSION: Although refractive astigmatism decreased in both groups, multifocal toric IOL implantation was predictable with good rotational stability. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2014; 40:1625–1632 Q 2014 ASCRS and ESCRS
Modern cataract surgery is no longer simply extraction of the lens content and implantation of a spherical intraocular lens (IOL). Surgeons can now select from IOLs with more complex optics, and these IOLs may better meet patients' visual expectations in terms of spectacle independence. The number of patients expecting to function at all distances without spectacles after uneventful cataract surgery has steadily increased in the past few years. However, multifocal IOLs have been shown to have poor performance in patients with moderate to high degrees of residual postoperative astigmatism.1,2 Managing Q 2014 ASCRS and ESCRS Published by Elsevier Inc.
preexisting corneal astigmatism at the time of cataract surgery is integral to achieving optimum refractive outcomes. It is estimated that approximately 40% of patients having cataract surgery have astigmatism of more than 1.00 diopter (D).3 Different methods are used to reduce preoperative corneal astigmatism during cataract surgery. This study compared 2 of these methods in eyes with moderate astigmatism. With multifocal toric IOLs, the combination of multifocal and toric optical components allows the potential benefit of reduced spectacle dependence 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2014.01.037
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to be extended to patients with significant corneal astigmatism. This would prevent them from requiring additional procedures, such as peripheral corneal relaxing incisions (PCRIs),4 opposite clear corneal incisions (CCIs), or even refractive laser surgery, during or after cataract surgery.5,6 The only drawback is the added extra cost of multifocal toric IOLs. However, although less expensive alternatives, such as limbal relaxing incisions, have been used for decades to reduce astigmatism during cataract surgery,7,8 they appear to be relatively unpredictable and may lead to need for further enhancement surgery to achieve full correction.4 The aim of this study was to compare the outcomes of multifocal toric IOL implantation with those of standard nontoric multifocal IOL implantation combined with PCRIs in patients with moderate preexisting corneal astigmatism. PATIENTS AND METHODS This randomized bilateral patient-masked and examinermasked study included patients who were scheduled for cataract surgery in both eyes and who desired spectacle independence. All research and measurements followed the tenets of Declaration of Helsinki, and the local ethics committee approved the study. All patients provided informed consent before the procedure. Inclusion criteria were bilateral corneal astigmatism between 1.0 and 2.5 D on automated keratometry performed with partial coherence interferometry (PCI) (IOLMaster, software version 5.x, Carl Zeiss Meditec AG); visually significant cataract in both eyes; and age of 40 years or older. Exclusion criteria were irregular astigmatism or forme fruste keratoconus on Scheimpflug corneal tomography (Pentacam HR, Oculus Optikger€ate GmbH), corneal scars, phacodonesis, pseudoexfoliation syndrome, traumatic cataract, and other ophthalmic copathology that could
Submitted: September 10, 2013. Final revision submitted: December 29, 2013. Accepted: January 13, 2014. From Moorfields Eye Hospital NHS Foundation Trust (Gangwani, Hirnschall, Findl, Maurino), London, United Kingdom; the Department of Ophthalmology (Hirnschall), Vienna Institute for Research in Ocular Surgery–A Karl Landsteiner Institute, Hanusch Hospital, Vienna, Austria. Supported by the Department of Health through an award made by the National Institute for Health Research to Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology for a Specialist Biomedical Research Centre for Ophthalmology. The views expressed in this publication are those of the authors and not necessarily those of the Department of Health. Also supported by an unrestricted grant from Rayner Surgical, United Kingdom. Corresponding author: Vincenzo Maurino, MD, Moorfields Eye Hospital, City Road, London EC1V 2PD, United Kingdom. E-mail: [email protected].
have an impact on capsular bag stability or postoperative visual function. All patients were recruited from December 2009 to December 2010. Each patient received a multifocal toric IOL in 1 eye and a nontoric multifocal version of the same IOL platform (M-Flex, Rayner Intraocular Lenses, Ltd.) combined with 1 or 2 PCRIs in the contralateral eye to allow for intraindividual comparison. The second eye was operated on within 4 weeks of the first surgery and received the alternate treatment. Group allocation of the first eye was random. Randomization was performed using a computer-based system by a person otherwise not involved in the trial. The patient and examiners were masked to the group allocation, and the surgeon was masked to allocation until the time of IOL implantation. The target postoperative refraction was emmetropia to slight hyperopia (0.00 to 0.25 D). One of 2 experienced surgeons (O.F., V.M.) performed the operations, with the same surgeon operating on both eyes of a patient.
Preoperative Marking and Surgical Technique Preoperatively, the horizontal meridian was marked with the patient sitting at the slitlamp and the patient's head straight in the chinrest. The slit beam was positioned in the retroillumination position and the slit oriented horizontally, centered on the pupil. Small superficial incisions were made at the periphery of the cornea into the epithelium using an insulin needle (30-gauge) at the 3 o’clock and 9 o’clock positions as well as at the 12 o’clock meridian with the slit in the vertical position. Care was taken to center the slit beam on the center of the pupil for alignment.9 Color was added to the 3 incisions with a sterile marking pen for easier recognition intraoperatively. Finally, the correct position markings were verified at the slitlamp. If a marking was slightly off the intended meridian, this was recorded on the biometry report form to aid the surgeon when positioning the corneal marker intraoperatively. Surgery was performed using topical anesthesia in both groups. After the Mendez-style corneal marking ring was aligned to the 3 preoperative markings, blue pen dots were made on the planned meridian. Incisions were made as per recommendation in each group. This was followed by injection of an ophthalmic viscosurgical device (OVD). Next, a capsulorhexis was created and phacoemulsification and irrigation/aspiration (I/A) of cortical material were performed. Then, a cohesive OVD (sodium hyaluronate 1.0% [Provisc]) was injected into the capsular bag and the IOL implanted. All patients received an intracameral injection of 1 mg/ 0.1 mL cefuroxime at the end of surgery. Postoperatively, patients received dexamethasone eyedrops 0.1% 4 times a day, which were tapered over 4 weeks, and chloramphenicol eyedrops for 3 weeks.
Toric Intraocular Lens Group The Mflex-T multifocal toric IOL is hydrophilic acrylic and injectable. It is based on multizone refractive aspheric optic technology, with 4 or 5 annular zones (depending on IOL base power) providing C3.00 D or C4.00 D of additional refractive power at the IOL plane (equivalent to C2.25 D or C3.00 D at the spectacle plane). At present, this IOL is manufactured as model 588F and model 638F, which have a 5.75 mm optic or a 6.25 mm optic, respectively. The standard power range is C14.00 D to C32.00 D in 0.50 D increments for sphere and 10.00 D to 6.00 D in 0.50 D increments
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for cylinder. The model selection was made automatically by the manufacturer so the largest possible diameter optic was supplied for any combination of sphere, cylinder, and injector nozzle. Model 638F is designed for low-power and medium-power IOLs, and model 588F is designed for higher power IOLs. Power calculation and the orientation for the toric IOLs were calculated using an online software program from the IOL manufacturer.A Preoperative keratometry and biometry data, incision location, and the surgeon's estimated corneal surgically induced astigmatism of 0.05 D (incision size 2.65 mm) were used to determine the appropriate toric IOL model, spherical equivalent (SE) IOL power, and meridian of placement in the eye. The SRK/T formula10 was used for spherical IOL power calculation when axial length (AL) was 22.0 mm or longer and the Hoffer Q11 formula when the AL was less than 22.0 mm. The toric IOL was implanted in the capsular bag using the injector provided with the IOL. The steep axes markings of the toric IOL were then positioned approximately 20 degrees counterclockwise from the planned meridian of placement by rotating the IOL, after which the OVD was aspirated thoroughly using a bimanual I/A set. Care was taken to completely remove the OVD from behind the IOL by slightly displacing and tilting the IOL and reaching behind the optic with the aspiration cannula. Thereafter, the toric IOL was rotated further clockwise until, in the surgeons' opinion, perfect alignment with the corneal marks was achieved. A final check was made after the anterior chamber was filled and the incisions were hydrated.
Peripheral Corneal Relaxing Incision Group Calculations for the PCRI group were performed with the Donnenfeld nomogram using an online calculator.B A CCI (2.65 mm) on the steep meridian was preferred and combined with a single opposite PCRI. In cases in which creating a CCI on the steep meridian was awkward, such as superonasal incisions in deep-set eyes, a temporal incision combined with 2 PCRIs was created. One surgeon (V.M.) performed all PCRIs at the start of surgery, while another surgeon (O.F.) performed all PCRIs at the end of surgery. Both surgeons used an identical 600 mm guided steel blade (Micro Feather ophthalmic scalpel with aluminum handle, No: 7360G, Feather Safety Razor Co. Ltd.). The depth of the PCRIs was 600 mm, and the length was as per the nomogram.
Patient Assessment Scheimpflug corneal tomography was performed preoperatively in all eyes to rule out irregular astigmatism and ensure the eye had normal corneal thickness. Surgically induced astigmatism of 0.50 D was taken into account during the calculations in both groups. Patients were examined 1 month and 3 months postoperatively. Monocular uncorrected distance visual acuity (UDVA) using distance Early Treatment Diabetic Retinopathy Study (ETDRS) charts (Precision Vision), corrected distance visual acuity (CDVA), autorefraction (Topcon RM-8800), and subjective refraction using the Jackson cross-cylinder method and trial frames were recorded for all patients. Near vision was tested using the near-vision ETDRS chart at 40 cm. Glare testing was performed using a straylight meter (C-Quant, Oculus Optikger€ ate GmbH), and contrast sensitivity was measured using
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Pelli-Robson charts (Precision Vision) at 1 m. Patient satisfaction was also recorded using a simple questionnaire. This questionnaire asked whether the patient experienced glare or halos and if so, whether these symptoms bothered the patient. Patients were also asked whether they thought that 1 of their eyes had better vision than the fellow eye. The IOL toric axis was assessed using retroillumination photographs performed 1 hour, 1 month, and 3 months after surgery. Details of the photographic technique have been described.12 For rotational stability analysis, Keynote software (version 5.0.2, Apple, Inc.) was used. All retroillumination images were imported into the software system. Images were not analyzed if the markings on the IOL were not visible because of a small pupil. To avoid observer bias due to knowledge of the IOL orientation on the previous follow-up photograph of a patient, all images were imported in random to ensure that the images of each patient were not analyzed consecutively. Two, thin (0.25 pixel) straight lines were adjusted to the marking on the IOL after magnifying the images. Each line touched the toric marking on the IOL on each side so that as a result, the 2 lines were parallel to the marking between the lines. The axes of both lines were entered into an Excel spreadsheet (Microsoft Corp.), and the mean value of both lines was used for further statistical analysis.
Statistical Analysis Astigmatism vector analysis was performed using Thibos and Horner's power vector notation.13 For statistical analysis, Excel 2011 for Mac with a Statplus:mac version 5.8.3.8 plugin (Analystsoft) and an Xlstat 2012 plugin (Addinsoft) was used. Descriptive data are shown as the mean G standard deviation. To compare measurements of the same eye at different timepoints, the analysis of variance and analysis of covariance for repeated measurements was used, if not stated otherwise. In all other cases, the test used is shown next to the P value. In general, a P value below 0.05 was considered significant (with a power of more than 80%).
RESULTS This study comprised 58 eyes of 29 patients. Three patients were lost to follow-up, 1 due to general health problems and 2 due to noncompliance, and were excluded from analysis. The mean age of the remaining patients was 74.8 years G 4.6 (SD); the male-tofemale distribution was 13:14. Astigmatism The mean preoperative corneal astigmatism measured with the PCI device was 1.82 G 0.45 D (maximum 2.58 D) in the toric IOL group and 1.67 G 0.58 D (maximum 2.57 D) in the PCRI group. The difference between the toric IOL group and the PCRI group was not statistically significant (P Z .29, Wilcoxon signed-rank test). Therefore, it was not necessary to adjust the postoperative astigmatism outcome to the baseline values for further analysis. The mean residual refractive astigmatism 3 months
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Figure 1. Vector differences between the preoperative keratometry and the astigmatism in subjective refraction at the 3-month postoperative follow-up in diopters (PCRI Z peripheral corneal relaxing incision).
after cataract surgery assessed by subjective refraction was 0.45 G 0.49 D (maximum 1.50 D) in the toric IOL group and 0.72 G 0.61 D (maximum 2.00 D) in the PCRI group. The difference between the 2 groups was statistically significant (P Z .046, Wilcoxon signed-rank test). Figure 1 shows the distribution of the postoperative residual astigmatism. The mean astigmatism vector difference from the target astigmatism was 0.22 G 0.25 D (maximum 0.75 D) in the toric IOL group and 0.36 G 0.30 D (maximum 1.00 D) in the PCRI group. This difference was not statistically significant (P Z .314). Concerning astigmatism vector reduction, measured as corneal astigmatism in keratometry with the PCI device preoperatively and using the subjective refractive astigmatism refraction 3 months postoperatively, the mean absolute vector difference (mean absolute error) was 1.76 G 0.47 D in the toric IOL group and 1.56 G 0.63 D in the PCRI
group. The difference between the 2 groups was statistically significant (P Z .042, Wilcoxon signedrank test). Visual Quality The mean B-vector distance (SE C J0 C J45) was 0.58 G 0.29 D in the toric IOL group and 0.62 G 0.40 D in the PCRI group. The difference was not statistically significant. Table 1 shows the results for all other visual quality parameters. Toric Intraocular Lens Rotation The mean absolute misalignment from the intended positioning axis of toric IOLs at the 3-month follow-up was 2.52 G 1.97 degrees (Figure 2, top). The maximum misalignment was 6.0 degrees. The mean absolute rotation in the toric IOL group between the 1-hour to 3-month postoperative photographs was 1.68 G 1.18
Table 1. Postoperative visual acuity and contrast sensitivity. Group/Parameter Toric IOL (mean G SD) PCRI (mean G SD) P value
LogMAR UDVA
LogMAR UNVA
Photopic CS (Log Units)
Mesopic CS (Log Units)
Log(s)
0.10 G 0.14 0.15 G 0.14 .120
0.43 G 0.11 0.39 G 0.10 .078
1.56 G 0.26 1.51 G 0.22 .243
1.29 G 0.25 1.16 G 0.32 .143
1.18 G 0.18 1.14 G 0.20 .14
CS Z contrast sensitivity; Log(s) Z log (straylight parameter); PCRI Z peripheral corneal relaxing incision; UDVAZ uncorrected distance visual acuity; UNVA Z uncorrected near visual acuity
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Figure 2. Misalignment and rotation of toric multifocal IOLs in degrees (amounts on the y-axes).
degrees (Figure 2, bottom). In 24 cases (90.9%), the rotation was within G3 degrees; in all cases it was within G6 degrees. In 14 cases (54.5%), the rotation was within G1.5 degrees. In 12 cases (45.5%), the toric IOL rotated more than 1.5 degrees clockwise; in no case did it rotate more than 1.5 degrees counterclockwise. Questionnaire On the questionnaire, all patients reported that they were not wearing spectacles most of the time, although 9 patients (52.9%) needed spectacles when reading for a long time. Seven patients (41%) reported glare and 6 (35%) reported halos; no patient reported being bothered by these phenomena. One patient identified the eye with a toric IOL as the better eye and 1 patient the eye with the PCRI. None of these findings was statistically significant. DISCUSSION Multifocal toric IOL implantation and performing PCRIs reduced preoperative low to moderate corneal
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astigmatism. Comparison with previous studies is difficult because, to our knowledge, this is the first study evaluating an acrylic multifocal toric IOL with a hydrophobic surface and an open-loop haptic design. There are 3 multifocal toric IOLs on the market; however, they differ in design (Acri.Lisa toric, Carl Zeiss Meditec AG, and Lentis Mplus toric, Oculentis GmbH) or material (Acrysof IQ Restor toric, Alcon Laboratories, Inc., and Tecnis multifocal toric, Abbott Medical Optics, Inc.).14 In our study, the astigmatism was reduced in both groups but slightly more so in the toric IOL group. These findings are similar to those by Mingo-Botín et al.15 Although their study was not bilateral and they used a different toric IOL, the studies are comparable because they included a similar range of preoperative corneal astigmatism and performed the same astigmatism vector analysis. Residual refractive astigmatism was less than 1.00 D in 90% of eyes in the Botín et al. study (96% in our study) in the toric IOL group and in 40% of eyes (84% in our study) in the PCRI group. This large difference in the PCRI group between the studies could be explained by the fact that different PCRI nomograms were used or, more likely, that the preoperative corneal astigmatism was lower in our study. These findings are contrary to observations by Poll et al.,16 who did not observe a significant difference between the 2 astigmatism-reducing methods. Their study was not bilateral and not prospective. Furthermore, there was a significant difference between the toric IOL group and the PCRI group, and this difference was not adequately taken into account in the postoperative analysis. In addition, their study mainly focused on the difference between preoperative and postoperative astigmatism; however, no significance levels and little explanation for the vector analysis were given. Although no studies of residual astigmatism with the IOL used in this study are available, overall results are similar to those reported for other toric IOLs. Very similar results were reported by Holland et al.17 for the Acrysof toric IOL (53% %0.50 D; 88% %1.00 D); others reported slightly better results.18–20 Residual astigmatism was reported to be higher for the Staar IOL21 (Staar Surgical) (49% %0.50 D; 78% %1.0 D) and for the Microsil toric IOL (Humanoptics AG) 22 (25% %0.50 D; 50% %1.00 D). Astigmatism vector reduction 3 months postoperatively in the PCRI group in this study was similar to findings by Kaufmann et al.23 (1.10 D after 6 months) and Budak24 (1.47 D after 1 month). Prediction of residual astigmatism remains difficult and depends on many factors, such as inaccurate preoperative keratometry,25,26 not taking the
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posterior surface of the cornea into account,27 inaccurate preoperative marking,9 potential mislabeling of the toric IOL, the impact of an unexpectedly deep or flat anterior chamber depth postoperatively,28 inaccurate placement of the IOL during surgery, and postoperative decentration and/or tilt or rotation of the IOL. All these can decrease the predictability of the residual refractive astigmatism. Furthermore, assessing subjective refraction has been shown to be inaccurate.26 The UDVA findings in a study by Cez on Prieto and Bautista29 were similar to those with the multifocal nontoric design of the same IOL when the preoperative astigmatism was below 1.00 D; however, their uncorrected near visual acuity (UNVA) results were slightly better. Visser et al.30 studied the AT Lisa toric multifocal toric IOL (Carl Zeiss Meditec AG), which is diffractive. They found slightly better UDVA and UNVA than in our study. In our study, there was no significant difference between the UDVA in the 2 groups, although there was a trend for slightly better visual acuity in the toric group. In a similar study by Mingo-Botín et al.,15 the UDVA was significantly better in the toric group. In 2 other studies, the UDVA with the same IOLs as in our study was observed. Whereas Entabi et al.31 observed that 18% of patients had a UDVA of better than 20/25, Stewart and McAlister32 observed that 36% of all patients had an UDVA of better than 20/ 25. However, UDVA depends on many factors and is, therefore, a weak parameter for IOL evaluation purposes. In our opinion, it would be more interesting to show the difference between the CDVA and the UDVA to assess the effects of astigmatism-reducing methods. The rotational stability of the toric IOL we used in our study was good and slightly better than in other studies of the same toric IOL.31,32 Other toric IOLs, such as open-loop acrylic models (Acrysof toric), showed similar to slightly worse rotational stability.12,17,33,34 Worse rotational stability was observed for Z-haptic toric IOLs (Microsil 6116TU, Humanoptics AG).22,35 Hydrophilic acrylic platehaptic IOLs (Acri-Comfort, Carl Zeiss Meditec AG) also showed good rotational stability of 2 degrees35 to 2.6 degrees (Acri.Smart 46S, Carl Zeiss Meditec AG),36 similar to that in our study. In our study, counterclockwise rotation occurred but there was no clockwise rotation of more than 1.5 degrees. This may be because the haptics of the IOL we used are slightly more bulky than those of other toric IOL models. These findings are contrary to those with open-loop haptics. A higher proportion of IOLs with open-loop haptics showed clockwise rotation, possibly because of the haptic compression resulting
from capsule collapse and fibrosis.12 However, it should be taken into account that measurements of the rotational stability of toric IOLs are not completely accurate. The measurement method used in this study has been shown to be highly reproducible12 and similar to more technical analyzing methods.37–39 However, none of these methods is free of errors and small deviations may be the result of cyclorotation of the eye during standardized photography.40 In this study, approximately 40% of all patients reported glare and one third reported experienced halos; however, none of the patients were bothered by these phenomena. The percentage of glare and halos was lower than that for the same nontoric IOL design but in patients with low astigmatism.29 In our study, none of the patients reported requiring spectacles all the time, although 52.9% said they needed spectacles when reading for a long time. Toric IOLs lack the side effects of PCRIs, such as transient foreign-body sensation shortly after surgery, decreased corneal sensitivity, risk for corneal infection, and potentially more pronounced dry-eye syndrome after surgery. Toric IOLs, however, increase the costs of surgery and in most countries, they are not covered by insurance companies or the public health system. To summarize, both toric IOLs and PCRIs reduced astigmatism. However, toric IOLs were found to have several advantages over PCRIs. With the toric IOLs, astigmatism reduction was more pronounced, the interpatient deviation in postoperative astigmatism was smaller; therefore, the toric IOLs were more predictable. In addition, there was no regression effect with the toric IOLs.
WHAT WAS KNOWN Toric IOLs and PCRIs successfully reduce preoperative corneal astigmatism. Modern toric IOLs show a good rotational stability. WHAT THIS PAPER ADDS Astigmatism was reduced in both groups, but predictability was slightly higher in the toric IOL group. The rotational stability of the IOL investigated was good.
REFERENCES 1. Hayashi K, Hayashi H, Nakao F, Hayashi F. Influence of astigmatism on multifocal and monofocal intraocular lenses. Am J Ophthalmol 2000; 130:477–482
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J CATARACT REFRACT SURG - VOL 40, OCTOBER 2014
First author: Vinod Gangwani, MRCOphth, FRCS Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
