- Email: [email protected]
Clinical outcomes after implantation of a new hydrophobic acrylic toric IOL during routine cataract surgery
ARTICLE
Clinical outcomes after implantation of a new hydrophobic acrylic toric IOL during routine cataract surgery Amy L. Sheppard, PhD, James S. Wolffsohn, PhD, Uday Bhatt, MD, Peter C. Hoffmann, MD, Andreas Scheider, MD, Werner W. H€ utz, MD, Sunil Shah, MD
PURPOSE: To assess the clinical outcomes after implantation of a new hydrophobic acrylic toric intraocular lens (IOL) to correct preexisting corneal astigmatism in patients having routine cataract surgery. SETTING: Four hospital eye clinics throughout Europe. DESIGN: Cohort study. METHODS: This study included eyes with at least 0.75 diopter (D) of preexisting corneal astigmatism having routine cataract surgery. Phacoemulsification was performed followed by insertion and alignment of a Tecnis toric IOL. Patients were examined 4 to 8 weeks postoperatively; uncorrected distance visual acuity (UDVA), corrected distance visual acuity, manifest refraction, and keratometry were measured. Individual patient satisfaction with uncorrected vision and the surgeon’s assessment of ease of handling and performance of the IOL were also documented. The cylinder axis of the toric IOL was determined by dilated slitlamp examination. RESULTS: The study enrolled 67 eyes of 60 patients. Four to 8 weeks postoperatively, the mean UDVA was 0.15 logMAR G 0.17 (SD) and the UDVA was 20/40 or better in 88% of eyes. The mean refractive cylinder decreased significantly postoperatively, from 1.91 G 1.07 D to 0.67 G 0.54 D. No significant change in keratometric cylinder was observed. The mean absolute IOL misalignment from the intended axis was 3.4 degrees (range 0 to 12 degrees). The good UDVA resulted in high levels of patient satisfaction. CONCLUSION: Implantation of the new toric IOL was an effective, safe, and predictable method to manage corneal astigmatism in patients having routine cataract surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2013; 39:41–47 Q 2012 ASCRS and ESCRS
Toric intraocular lenses (IOLs) were conceptualized by Shimizu et al. in 19941 to correct preexisting astigmatism resulting from corneal toricity. Given that approximately 60% of cataractous eyes have more than 0.75 diopter (D) of corneal astigmatism2,3 and uncorrected astigmatism results in reduced visual acuity and increased spectacle dependence,4,5 predictable and effective toric IOL models are required to provide patients with optimum visual outcomes. Surgical correction of astigmatism is preferable to spectacle use, which induces meridional magnification and spatial distortion.6 Correction of astigmatism on the cornea can be achieved using surgical techniques, such as corneal or limbal relaxing incisions, or by Q 2012 ASCRS and ESCRS Published by Elsevier Inc.
varying the placement of the incision site.7,8 However, such techniques are associated with several limitations, including poorer predictability in eyes with higher levels of astigmatism due to variable tissue healing and long-term mechanical instability.9,10 Toric IOLs may therefore represent a more stable and predictable method for correcting preexisting corneal astigmatism.11 Several studies12–17 report clinical findings after implantation of various models of toric IOLs. Successful visual outcomes rely on careful alignment of the toric IOL with its intended axis and minimal postoperative rotation; approximately 3% of cylinder power is lost for every 1 degree of off-axis rotation.1 The new Tecnis 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2012.08.055
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HYDROPHOBIC ACRYLIC TORIC IOL
toric IOL (Abbott Medical Optics, Inc.) has 3-point fixation (haptic–lens–haptic) in the capsular bag to stabilize the position of the IOL and reduce undesirable rotation. The purpose of this study was to evaluate visual outcomes and patient and surgeon satisfaction with the new toric IOL in a non-interventional setting under routine conditions. PATIENTS AND METHODS This prospective observational study included astigmatic eyes having routine cataract surgery with implantation of the Tecnis toric IOL. Surgery took place at 4 hospital departments across Europe between January 2011 and March 2011. The research was approved by the local ethics committees and adhered to the tenets of the Declaration of Helsinki. Informed consent was obtained from all patients before participation. Patients with cataract scheduled for routine phacoemulsification cataract surgery and IOL implantation with at least 0.75 D of preoperative regular corneal astigmatism were enrolled in the study. Because the study was a noninterventional trial, patient selection was not limited beyond the indications of the product (ie, adults with cataract and corneal astigmatism listed for routine cataract surgery).
Preoperative Assessment All patients had a complete ophthalmic examination before cataract surgery that included manifest refraction, logMAR corrected visual acuity (CDVA), axial length measurement with the IOLMaster partial coherence interferometry (PCI) device (Carl Zeiss Meditec AG), and dilated slitlamp evaluation. Keratometry was primarily measured automatically with the PCI device, although manual keratometry was permitted. Corneal topography to exclude irregular astigmatism was optional. When topography was not available, the previous ophthalmic history was examined and the refractive and corneal astigmatism were compared; eyes with a significant disparity between these values were excluded from the study. The IOL
manufacturer’s web-based toolA was used to determine the required cylindrical power of the IOL and the axis of placement in the eye from preoperative keratometry and biometry data, the preferred incision location, and the surgeon’s estimated surgically induced corneal astigmatism (eg, 0.40 D).
Intraocular Lens The Tecnis toric 1-piece IOL, launched in 2010, has a proprietary wavefront-designed toric aspheric optic aimed at compensating for corneal spherical aberration and correct astigmatism (Figure 1). The optic is 6.0 mm in diameter and has a 360-degree square edge with frosting to reduce migration of lens epithelial cells (LECs) and possible edge glare effects. The overall length of the IOL is 13.0 mm. The C-loop haptics, offset to the optic, provide 3-point fixation on the capsular bag with the goal of maintaining good centration and rotational stability. The hydrophobic acrylic material has a high Abbe value of 55 (compared with 47, 43, and 37 for the natural crystalline lens and the Hoya and Alcon acrylic IOL materials, respectively); reduced longitudinal chromatic aberration improves optical quality and can increase contrast sensitivity.18 Available parameters for the toric IOL are C5.00 to C34.00 D spherical equivalent (SE) in 0.50 D steps and 1.00 D, 1.50 D, 2.25 D, 3.00 D, and 4.00 D cylinder powers. At the time of the study in 2011, the maximum available cylinder power was 3.00 D. Cylinder axis marks (4 dots) on the anterior surface of the IOL denote the meridian with the lowest power.
Surgical Technique Before surgery, topical anesthetic eyedrops (eg, benoxinate 0.4%) were instilled into the operative eye. With the patient sitting upright with his or her head in the vertical position to avoid cyclorotation, a single-use ophthalmic marking pen was used to mark the corneal limbus at the 12 o’clock and 3 o’clock positions. The surgeons used their preferred marking technique, which was freehand or with a Bakewell bubble level (Mastel, Inc.). Intraoperatively, these marks enabled determination of the required axis of IOL orientation using the individual surgeon’s preferred instrument; for example, a Mendez ring with a Nuijts toric axis (America Surgical Instruments Corp.).
Submitted: March 29, 2012. Final revision submitted: August 7, 2012. Accepted: August 8, 2012. From the School of Life and Health Sciences (Sheppard, Wolffsohn, Bhatt, Shah), Aston University, Birmingham, and the Midland Eye Institute (Shah), West Midlands, United Kingdom; Eye & Laser Clinic Castrop-Rauxel (Hoffmann), Castrop-Rauxel, the Department of Ophthalmology (Scheider), Kliniken Essen Sued, Essen, and the Department of Ophthalmology (H€utz), Klinikum Bad Hersfeld, Bad Hersfeld, Germany. Supported by Abbott Medical Optics, Inc. Presented at the XXIX Congress of the European Society of Cataract & Refractive Surgeons, Vienna, Austria, September 2011. Corresponding author: Amy L. Sheppard, PhD, School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, United Kingdom. E-mail: [email protected].
Figure 1. The toric IOL used in the study. The dotted lines indicate the meridian with the lowest power (IOL Z intraocular lens).
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After phacoemulsification, the foldable toric IOL was inserted in the capsular bag using the Unfolder Platinum 1 series implantation system (Abbott Medical Optics, Inc.). Gross alignment of the IOL with its intended axis was achieved by rotating the IOL as it unfolded. After careful removal of all ophthalmic viscosurgical device (OVD) from the capsular bag to prevent undesirable IOL rotation, the IOL was rotated to the correct axis to complete surgery.19
Postoperative Assessment In addition to the routine postoperative management offered by individual surgeons, patients were assessed 4 to 8 weeks postoperatively. At this visit, manifest refraction, logMAR uncorrected distance visual acuity (UDVA), and logMAR CDVA were recorded and keratometry was performed using the PCI device. Pupil dilation of operative eyes was achieved by topical application of tropicamide 1.0% (with phenylephrine 2.5% if necessary), and the toric axis was measured at the slitlamp using a thin coaxial slit that was rotated until it overlapped the axis markings on the IOL. As well as clinical findings, patients were questioned regarding postoperative experiences of optical/visual disturbances (eg, arcs of light, halos, ghosting, day glare, night glare) and asked to rate their satisfaction with their level of uncorrected vision on a scale of 1 to 5 (1 Z not at all happy; 5 Z very happy). Surgeons used similar scales of 1 to 5 to rate ease of use of the Tecnis toric IOL calculator, ease of IOL implantation, achievement of target refraction, and overall satisfaction with the IOL. Surgeons documented these satisfaction scores for all eyes treated in the study. All data were entered into online case-report forms.
Data and Statistical Analysis Preoperative and postoperative J0 and J45 cylindrical vectors (refractive and keratometric) were computed using an Excel worksheet (2010 version, Microsoft Corp.) as follows20: J0 Z (cylinder/2)cos(2 axis); J45 Z (cylinder/2) sin(2 axis). SPSS for Windows software (version 18.0, SPSS, Inc.) was used for statistical analysis. Following a Kolmogorov-Smirnov test for normality, if parametric analysis was possible, a paired t test was performed to compare parameters between preoperative visits and postoperative visits. The Wilcoxon rank-sum test was used when data were not normally distributed to identify significant changes between preoperative values and postoperative values. A P value of 0.05 or less was considered statistically significant. Linear regression analysis was used to analyze the association between the intraoperative axis and the level of postoperative misalignment from the intended axis.
RESULTS Sixty-seven eyes of 60 patients were enrolled in the study. Postoperative determination of the axis of the IOL was performed in 61 eyes. Table 1 shows the patients’ demographics and preoperative data. Complications There were no intraoperative complications. One eye developed postoperative cystoid macular edema,
Table 1. Patient demographics and preoperative data. Parameter Patients (n) Eyes (n) Age (y) Mean G SD Range Sex, n (%) Male Female Preop refractive sphere (D) Mean G SD Range Preop refractive cylinder (D) Mean G SD Range Mean preop keratometry (D) G SD K1 (steep) K2 (flat) Axial length (mm) Mean G SD Range Mean IOL power (D) G SD Sphere Cylinder
Value 60 67 74.1 G 9.6 46, 92 22 (36.7) 38 (63.3) C0.20 G 2.54 7.00, C6.00 1.91 G 1.07 0.50, 4.75 45.24 G 1.96 42.91 G 1.90 23.48 G 1.10 21.60, 26.80 21.68 G 2.60 2.50 G 0.54
IOL Z intraocular lens
and a second patient had a hypersensitivity reaction to the topical antibiotic and steroid medication, which caused significant facial and ocular redness with a reduction in visual acuity. These patients did not attend the 4- to 8-week postoperative assessments because they were receiving alternative ophthalmic care; thus, they were not included in statistical analyses. However, the final CDVA was 0.1 logMAR in both eyes. Visual Acuity Table 2 shows the preoperative and postoperative refractive data, UDVA, and CDVA. At the 4- to 8-week visit, the mean UDVA was approximately 20/30, which improved slightly with refractive correction to approximately 20/25. The UDVA was 20/40 (0.3 logMAR) or better in 57 eyes (87.7%) (Figure 2). The postoperative CDVA was 20/40 (0.3 logMAR) or better in 62 eyes (95.4%), 20/30 (0.18 logMAR) or better in 50 eyes (76.9%), and 20/20 (0.0 logMAR) or better in 30 eyes (46.2%). Refraction Four to 8 weeks postoperatively, 62 eyes (95.4%) had a mean SE within G1.00 D of emmetropia. The level of refractive astigmatism decreased significantly
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Table 2. Mean preoperative and postoperative visual acuity and refraction.
Parameter Mean UDVA (logMAR) G SD Mean CDVA (logMAR) G SD Mean refractive sphere (D) G SD Mean SE (D) G SD Refractive cylinder (D) Mean G SD Range Keratometric cylinder (D) Mean G SD Range
Preop d
4 8 Wk Postop 0.15 G 0.17
P Value d
0.41 G 0.26
0.09 G 0.15 !.001*
0.20 G 2.54
0.24 G 0.66
.901
0.70 G 2.38
0.10 G 0.59
.034*
1.91 G 1.07 0.50, 4.75
0.67 G 0.54 !.001* 0.00, 2.25
2.21 G 0.91 0.78, 5.55
2.06 G 0.90 0.45, 5.55
.084
CDVA Z corrected distance visual acuity; SE Z spherical equivalent; UDVA Z uncorrected distance visual acuity *Statistically significant difference between preoperative and postoperative values at a Z 0.05 level
postoperatively (P ! .001; Table 2). Figure 3 shows the preoperative and postoperative J0 and J45 refractive cylinder vectors; the origin (0, 0) in Figure 3 represents an eye with no refractive astigmatism. Postoperatively, a concentration of data points around the origin is present compared with the preoperative spread. There was a significant reduction in the magnitude of the refractive J0 vector (P Z .002) postoperatively. The mean J45 vector did not change significantly (P Z .703); however, this would be expected given that the magnitude of the mean J45 vector was
Figure 2. Postoperative UDVA (65 eyes) (UDVA Z uncorrected distance visual acuity).
minimal preoperatively and postoperatively (0.04 D G 0.58 [SD] and 0.02 G 0.25 D, respectively), and not significantly different from zero (preoperative: P Z .528; postoperative: P Z .870). The keratometric J0 and J45 vectors did not change significantly between the preoperative and postoperative visits (J0: P Z .484; J45: P Z .982). Intraocular Lens Alignment No eye required additional surgery to rotate and reposition the IOL axis during the course of the study. The mean absolute IOL misalignment at the 4- to 8-week visit was 3.4 degrees (range 0 to 12 degrees). Nine eyes (14.7 %) had misalignment of more than 5 degrees; 1 eye (1.6%) had misalignment of more than 10 degrees. Linear regression analysis showed no significant association between the intraoperative axis position and postoperative alignment (P Z .27). Subjective Experience Patients Of the patients, 22 (37.9%) reported being very happy with their uncorrected vision postoperatively and 32 (55.2%) were happy (4 out of 5). Although all patients were at least moderately happy (3 out of 5) with their postoperative uncorrected vision, patient satisfaction was significantly associated with postoperative UDVA (y Z 4.834 – 2.481x; r Z 0.564; r2 Z 0.318; P ! .001). Optical or visual disturbances were rarely reported by patients attending the postoperative visit. Two patients (3%) reported daytime glare, both giving a score of 3 out of 5 for postoperative satisfaction with vision. The 4 ophthalmic surgeons described use of the toric online calculator as easy (4 out of 5) or very easy (5 out of 5) in 56 patients (96.6%). Regarding ease of IOL implantation, ease of alignment, and achievement of target refraction, surgeons scored 4 or 5 out of 5 in 55 patients (94.8%), 56 patients (96.5%), and 57 patients (98.3%), respectively. In terms
Surgeons
Figure 3. Preoperative and postoperative J0 and J45 cylindrical vectors (65 eyes).
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of overall refraction with the toric IOL, surgeons were satisfied or very satisfied in 54 patients (93.1%). DISCUSSION Use of toric IOLs during cataract surgery is one of several surgical options to correct corneal astigmatism and provide improved visual outcomes. The variability in healing responses associated with surgical flattening of the cornea results in a level of unpredictability regarding final outcomes.9,10 Thus, stable and effective toric IOLs implanted in the capsular bag during routine cataract surgery and requiring no modification of the cornea are an important advancement in modern cataract surgery. The present study, to our knowledge, is the first to describe application of the Tecnis toric IOL in a cohort of patients having routine cataract surgery. The results in the present study indicate that the Tecnis toric IOL is an effective means of treating corneal astigmatism of 0.75 D or more, with a statistically significant mean reduction in refractive astigmatism of 1.24 G 1.20 D. Postoperative refractive astigmatism ranged from 0.00 to 2.25 D (mean 0.67 G 0.54 D); the single eye with a 2.25 D postoperative cylindrical refraction had a preoperative 4.75 D refractive cylinder and 3.80 D of corneal toricity. Tecnis toric IOLs now come in cylinder powers of 1.00 D, 1.50 D, 2.25 D, 3.00 D, and 4.00 D (equivalent to 0.69 D, 1.03 D, 1.54 D, 2.06 D, and 2.74 D at the corneal plane, respectively). This range of cylinder powers allows application of the IOL in the majority of cataract patients with significant corneal astigmatism. The good standard of UDVA achieved in the study resulted in a high level of patient satisfaction with their uncorrected vision (93.1% of patients being happy or very happy), and a statistically significant association between these 2 factors was identified. The UDVA in the present study (mean 0.15 G 0.17 logMAR, with 88% of eyes having 20/40 or better) compares favorably with reports of outcomes with other toric IOLs. DeSilva et al.14 reported that 79% of eyes achieved 20/35 or better UDVA after implantation of the Microsil 6116TU (Humanoptics). Ali o et al.21 found a UDVA of at least 20/40 in 76% of eyes with moderate to high astigmatism implanted with the Acri.Comfort 646 TLC (Acri.Tec GmbH) and with various Acrysof toric models (Alcon Laboratories, Inc.). Bauer et al.17 found UDVA of at least 20/25 in 75% to 85% of eyes. Mendicute et al.13 identified a mean UDVA of 0.16 G 0.18 logMAR, with 93% of eyes achieving 20/40 or better, although the investigators excluded patients with macular degeneration and other ocular diseases that could reduce visual acuity. In the present study, which sought to evaluate
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the routine application of the Tecnis toric IOL, such exclusions were not made; all patients listed for routine cataract surgery with a minimum of 0.75 D of corneal astigmatism were eligible to participate; thus, the sample included several patients with early age-related macular degeneration and 1 patient with amblyopia (CDVA 0.3 logMAR in this eye). Postoperative rotational stability is vital to confer the best possible visual results with toric IOLs. The Tecnis toric IOL showed low levels of deviation from the target axis 4 to 8 weeks after implantation. Several mechanisms may result in undesirable postoperative IOL rotation. These include incomplete clearance of OVD, causing reduced friction between the haptics and the capsular bag,22 and early postoperative intraocular pressure fluctuations23; both are linked to rotational instability. Postoperative capsule shrinkage compresses IOL haptics and may cause rotation of certain IOL designs and materials. C-loop haptic IOLs were previously associated with high levels of postoperative rotation; Shimizu et al.1 reported more than 10 degrees of rotation in 41% of eyes 12 weeks postoperatively with a poly(methyl methacrylate) toric IOL. Although the Tecnis toric has C-loop haptics, its rotational stability is likely the result of factors related to its design and material. The 3-point fixation system (as the haptics are offset) and angled haptics that resist compression enable close contact between the IOL optic and posterior capsule.B Furthermore, the hydrophobic acrylic material can form bioactive bonds with fibronectin,24 an extracellular protein, resulting in a sandwich-like structure in which a single layer of LECs binds with the IOL and the posterior capsule.24,25 Such attachment may improve the rotational stability of the IOL and reduce the incidence of posterior capsule opacification. The low level of misalignment in the present study (mean 3.4 degrees; range 0 to 12 degrees) is in agreement with relatively recent reports of postoperative toric IOL stability. Mendicute et al.13 observed mean IOL rotation of 3.6 degrees in 30 eyes implanted with the Acrysof SN60T (Alcon Laboratories, Inc.) at 12 weeks, with 97% of the IOLs rotating less than 10 degrees. Chang26 compared the 4203TL/TF IOL (Staar) and the Acrysof SN60T at 1 month, finding a mean rotation of 5.6 G 8.49 degrees and 3.4 G 3.4 degrees, respectively. Entabi et al.15 report rotation of 3.4 degrees (range 0 to 12 degrees) at 16 weeks with the T-flex 623T IOL (Rayner). A limitation of the present study is that the follow-up period of 4 to 8 weeks did not permit long-term assessment of IOL stability. However, previously published studies indicate that most IOL rotation occurs in the early postoperative period, before fusion of the anterior and posterior capsules. Ahmed et al.16 and Kim et al.27
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identified minimal rotation of the Acrysof toric IOL, which is also composed of a hydrophobic acrylic material, between 1 month and 3 months postoperatively. No complications related to the new toric IOL model were observed in the present study. In summary, a significant reduction in refractive astigmatism resulting in good UDVA and high levels of patient and surgeon satisfaction were measured. The Tecnis toric IOL is based on the same platform as the Tecnis aspheric IOL and has a proprietary aspheric optic design to correct spherical aberration. The IOL is available in a broad range of cylinder powers, and data in the present study indicate good postoperative alignment with the intended axis. Hence, Tecnis toric IOL implantation appears to be an effective and predictable method of managing corneal astigmatism during routine cataract surgery. WHAT WAS KNOWN Approximately 60% of cataractous eyes have more than 0.75 D of corneal astigmatism. Stable and effective toric IOLs implanted into the capsular bag during routine cataract surgery are therefore an important requirement for modern cataract surgery, allowing correction of corneal astigmatism without modification of the cornea. WHAT THIS PAPER ADDS The new Tecnis toric 1-piece hydrophobic acrylic IOL effectively and predictably managed corneal astigmatism during routine cataract surgery. The IOL was associated with high levels of patient and surgeon satisfaction.
REFERENCES 1. Shimizu K, Misawa A, Suzuki Y. Toric intraocular lenses: correcting astigmatism while controlling axis shift. J Cataract Refract Surg 1994; 20:523–526 2. Hoffer KJ. Biometry of 7,500 cataractous eyes. Am J Ophthalmol 1980; 90:360–368; correction 890 €tz WW. Analysis of biometry and prevalence 3. Hoffmann PC, Hu data for corneal astigmatism in 23,239 eyes. J Cataract Refract Surg 2010; 36:1479–1485 4. Pesudovs K, Garamendi E, Elliott DB. A quality of life comparison of people wearing spectacles or contact lenses or having undergone refractive surgery. J Refract Surg 2006; 22:19–27 5. Wolffsohn JS, Bhogal G, Shah S. Effect of uncorrected astigmatism on vision. J Cataract Refract Surg 2011; 37:454–460 6. Guyton DL. Prescribing cylinders: the problem of distortion. Surv Ophthalmol 1977; 22:177–188 7. Grabow HB. Intraocular correction of refractive errors. In: Kershner RM, ed, Refractive Keratotomy for Cataract Surgery and the Correction of Astigmatism. Thorofare, NJ, Slack, 1994; 79–115
8. Troutman RC, Swinger C. Relaxing incision for control of postoperative astigmatism following keratoplasty. Ophthalmic Surg 1980; 11:117–120 9. Nichamin LD. Astigmatism control. Ophthalmol Clin North Am 2006; 19(4):485–493 10. Carvalho MJ, Suzuki SH, Freitas LL, Branco BC, Shor P, €ffling-Lima AL. Limbal relaxing incisions to correct corneal Ho astigmatism during phacoemulsification. J Refract Surg 2007; 23:499–504 ~oz-Negrete FJ, Kim HRW, Morcillo-Laiz R, 11. Mingo-Botın D, Mun Rebolleda G, Oblanca N. Comparison of toric intraocular lenses and peripheral corneal relaxing incisions to treat astigmatism during cataract surgery. J Cataract Refract Surg 2010; 36:1700–1708 12. Till JS, Yoder PR Jr, Wilcox TK, Spielman JL. Toric intraocular lens implantation: 100 consecutive cases. J Cataract Refract Surg 2002; 28:295–301 s13. Mendicute J, Irigoyen C, Aramberri J, Ondarra A, Monte R. Foldable toric intraocular lens for astigmatism correction Mico in cataract patients. J Cataract Refract Surg 2008; 34:601–607 14. 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 15. 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 16. 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 2010; 36:609–616 17. Bauer NJC, de Vries NE, Webers CAB, Hendrikse F, Nuijts RMMA. Astigmatism management in cataract surgery with the AcrySof toric intraocular lens. J Cataract Refract Surg 2008; 34:1483–1488 18. Zhao H, Mainster MA. The effect of chromatic dispersion on pseudophakic optical performance. Br J Ophthalmol 2007; 91:1225–1229. Available at: http://www.ncbi.nlm.nih.gov/pmc/ articles/PMC1954934/pdf/1225.pdf. Accessed September 1, 2012 19. Buckhurst PJ, Wolffsohn JS, Davies LN, Naroo SA. Surgical correction of astigmatism during cataract surgery. Clin Exp Optom 2010; 93:409–418 20. Thibos LN, Wheeler W, Horner D. Power vectors: an application of Fourier analysis to the description and statistical analysis of refractive error. Optom Vis Sci 1997; 74:367–375. Available at: http://journals.lww.com/optvissci/Abstract/1997/06000/Power_ Vectors__An_Application_of_Fourier_Analysis.19.aspx. Accessed September 1, 2012 JL, Agdeppa MCC, Pongo VC, El Kady B. Microincision cat21. Alio aract surgery with toric intraocular lens implantation for correcting moderate and high astigmatism: pilot study. J Cataract Refract Surg 2010; 36:44–52 22. Myers TD, Olson RJ. Comparison of the effects of viscoelastic agents on clinical properties of the Unfolder lens injection system. J Cataract Refract Surg 1999; 25:953–958 23. Pereira FAS, Milverton EJ, Coroneo MT. Miyake-Apple study of the rotational stability of the Acrysof toric intraocular lens after experimental eye trauma. Eye 2010; 24:776 378. Available at: http://www.nature.com/eye/journal/v24/n2/pdf/ eye2009150a.pdf. Accessed September 1, 2012 € nen R, Pihlajaniemi T. Adhesion of sol24. Linnola RJ, Sund M, Ylo uble fibronectin, vitronectin, and collagen type IV to intraocular lens materials. J Cataract Refract Surg 2003; 29:146–152 25. Linnola RJ, Werner L, Pandey SK, Escobar-Gomez M, Znoiko SL, Apple DJ. Adhesion of fibronectin, vitronectin,
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laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 1: histological sections. J Cataract Refract Surg 2000; 26:1792–1806 26. 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 27. Kim MH, Chung T-Y, Chung E-S. Long-term efficacy and rotational stability of AcrySof toric intraocular lens implantation in cataract surgery. Korean J Ophthalmol 2010; 24:207–212. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/ PMC2916101/pdf/kjo-24-207.pdf. Accessed September 1, 2012
B. Nixon DR, “Clinical Evaluation of an Investigational 1-Piece Acrylic Monofocal IOL,” presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Chicago, Illinois, USA, April 2008
OTHER CITED MATERIAL A. Abbott Medical Optics. AMO IOL calculator platform. Available at: www.TecnisToricCalc.com. Accessed September 1, 2012
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First author: Amy L. Sheppard, PhD School of Life and Health Sciences, Aston University, Birmingham, United Kingdom
Clinical outcomes after implantation of a new hydrophobic acrylic toric IOL during routine cataract surgery Amy L. Sheppard, PhD, James S. Wolffsohn, PhD, Uday Bhatt, MD, Peter C. Hoffmann, MD, Andreas Scheider, MD, Werner W. H€ utz, MD, Sunil Shah, MD
PURPOSE: To assess the clinical outcomes after implantation of a new hydrophobic acrylic toric intraocular lens (IOL) to correct preexisting corneal astigmatism in patients having routine cataract surgery. SETTING: Four hospital eye clinics throughout Europe. DESIGN: Cohort study. METHODS: This study included eyes with at least 0.75 diopter (D) of preexisting corneal astigmatism having routine cataract surgery. Phacoemulsification was performed followed by insertion and alignment of a Tecnis toric IOL. Patients were examined 4 to 8 weeks postoperatively; uncorrected distance visual acuity (UDVA), corrected distance visual acuity, manifest refraction, and keratometry were measured. Individual patient satisfaction with uncorrected vision and the surgeon’s assessment of ease of handling and performance of the IOL were also documented. The cylinder axis of the toric IOL was determined by dilated slitlamp examination. RESULTS: The study enrolled 67 eyes of 60 patients. Four to 8 weeks postoperatively, the mean UDVA was 0.15 logMAR G 0.17 (SD) and the UDVA was 20/40 or better in 88% of eyes. The mean refractive cylinder decreased significantly postoperatively, from 1.91 G 1.07 D to 0.67 G 0.54 D. No significant change in keratometric cylinder was observed. The mean absolute IOL misalignment from the intended axis was 3.4 degrees (range 0 to 12 degrees). The good UDVA resulted in high levels of patient satisfaction. CONCLUSION: Implantation of the new toric IOL was an effective, safe, and predictable method to manage corneal astigmatism in patients having routine cataract surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2013; 39:41–47 Q 2012 ASCRS and ESCRS
Toric intraocular lenses (IOLs) were conceptualized by Shimizu et al. in 19941 to correct preexisting astigmatism resulting from corneal toricity. Given that approximately 60% of cataractous eyes have more than 0.75 diopter (D) of corneal astigmatism2,3 and uncorrected astigmatism results in reduced visual acuity and increased spectacle dependence,4,5 predictable and effective toric IOL models are required to provide patients with optimum visual outcomes. Surgical correction of astigmatism is preferable to spectacle use, which induces meridional magnification and spatial distortion.6 Correction of astigmatism on the cornea can be achieved using surgical techniques, such as corneal or limbal relaxing incisions, or by Q 2012 ASCRS and ESCRS Published by Elsevier Inc.
varying the placement of the incision site.7,8 However, such techniques are associated with several limitations, including poorer predictability in eyes with higher levels of astigmatism due to variable tissue healing and long-term mechanical instability.9,10 Toric IOLs may therefore represent a more stable and predictable method for correcting preexisting corneal astigmatism.11 Several studies12–17 report clinical findings after implantation of various models of toric IOLs. Successful visual outcomes rely on careful alignment of the toric IOL with its intended axis and minimal postoperative rotation; approximately 3% of cylinder power is lost for every 1 degree of off-axis rotation.1 The new Tecnis 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2012.08.055
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toric IOL (Abbott Medical Optics, Inc.) has 3-point fixation (haptic–lens–haptic) in the capsular bag to stabilize the position of the IOL and reduce undesirable rotation. The purpose of this study was to evaluate visual outcomes and patient and surgeon satisfaction with the new toric IOL in a non-interventional setting under routine conditions. PATIENTS AND METHODS This prospective observational study included astigmatic eyes having routine cataract surgery with implantation of the Tecnis toric IOL. Surgery took place at 4 hospital departments across Europe between January 2011 and March 2011. The research was approved by the local ethics committees and adhered to the tenets of the Declaration of Helsinki. Informed consent was obtained from all patients before participation. Patients with cataract scheduled for routine phacoemulsification cataract surgery and IOL implantation with at least 0.75 D of preoperative regular corneal astigmatism were enrolled in the study. Because the study was a noninterventional trial, patient selection was not limited beyond the indications of the product (ie, adults with cataract and corneal astigmatism listed for routine cataract surgery).
Preoperative Assessment All patients had a complete ophthalmic examination before cataract surgery that included manifest refraction, logMAR corrected visual acuity (CDVA), axial length measurement with the IOLMaster partial coherence interferometry (PCI) device (Carl Zeiss Meditec AG), and dilated slitlamp evaluation. Keratometry was primarily measured automatically with the PCI device, although manual keratometry was permitted. Corneal topography to exclude irregular astigmatism was optional. When topography was not available, the previous ophthalmic history was examined and the refractive and corneal astigmatism were compared; eyes with a significant disparity between these values were excluded from the study. The IOL
manufacturer’s web-based toolA was used to determine the required cylindrical power of the IOL and the axis of placement in the eye from preoperative keratometry and biometry data, the preferred incision location, and the surgeon’s estimated surgically induced corneal astigmatism (eg, 0.40 D).
Intraocular Lens The Tecnis toric 1-piece IOL, launched in 2010, has a proprietary wavefront-designed toric aspheric optic aimed at compensating for corneal spherical aberration and correct astigmatism (Figure 1). The optic is 6.0 mm in diameter and has a 360-degree square edge with frosting to reduce migration of lens epithelial cells (LECs) and possible edge glare effects. The overall length of the IOL is 13.0 mm. The C-loop haptics, offset to the optic, provide 3-point fixation on the capsular bag with the goal of maintaining good centration and rotational stability. The hydrophobic acrylic material has a high Abbe value of 55 (compared with 47, 43, and 37 for the natural crystalline lens and the Hoya and Alcon acrylic IOL materials, respectively); reduced longitudinal chromatic aberration improves optical quality and can increase contrast sensitivity.18 Available parameters for the toric IOL are C5.00 to C34.00 D spherical equivalent (SE) in 0.50 D steps and 1.00 D, 1.50 D, 2.25 D, 3.00 D, and 4.00 D cylinder powers. At the time of the study in 2011, the maximum available cylinder power was 3.00 D. Cylinder axis marks (4 dots) on the anterior surface of the IOL denote the meridian with the lowest power.
Surgical Technique Before surgery, topical anesthetic eyedrops (eg, benoxinate 0.4%) were instilled into the operative eye. With the patient sitting upright with his or her head in the vertical position to avoid cyclorotation, a single-use ophthalmic marking pen was used to mark the corneal limbus at the 12 o’clock and 3 o’clock positions. The surgeons used their preferred marking technique, which was freehand or with a Bakewell bubble level (Mastel, Inc.). Intraoperatively, these marks enabled determination of the required axis of IOL orientation using the individual surgeon’s preferred instrument; for example, a Mendez ring with a Nuijts toric axis (America Surgical Instruments Corp.).
Submitted: March 29, 2012. Final revision submitted: August 7, 2012. Accepted: August 8, 2012. From the School of Life and Health Sciences (Sheppard, Wolffsohn, Bhatt, Shah), Aston University, Birmingham, and the Midland Eye Institute (Shah), West Midlands, United Kingdom; Eye & Laser Clinic Castrop-Rauxel (Hoffmann), Castrop-Rauxel, the Department of Ophthalmology (Scheider), Kliniken Essen Sued, Essen, and the Department of Ophthalmology (H€utz), Klinikum Bad Hersfeld, Bad Hersfeld, Germany. Supported by Abbott Medical Optics, Inc. Presented at the XXIX Congress of the European Society of Cataract & Refractive Surgeons, Vienna, Austria, September 2011. Corresponding author: Amy L. Sheppard, PhD, School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, United Kingdom. E-mail: [email protected].
Figure 1. The toric IOL used in the study. The dotted lines indicate the meridian with the lowest power (IOL Z intraocular lens).
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After phacoemulsification, the foldable toric IOL was inserted in the capsular bag using the Unfolder Platinum 1 series implantation system (Abbott Medical Optics, Inc.). Gross alignment of the IOL with its intended axis was achieved by rotating the IOL as it unfolded. After careful removal of all ophthalmic viscosurgical device (OVD) from the capsular bag to prevent undesirable IOL rotation, the IOL was rotated to the correct axis to complete surgery.19
Postoperative Assessment In addition to the routine postoperative management offered by individual surgeons, patients were assessed 4 to 8 weeks postoperatively. At this visit, manifest refraction, logMAR uncorrected distance visual acuity (UDVA), and logMAR CDVA were recorded and keratometry was performed using the PCI device. Pupil dilation of operative eyes was achieved by topical application of tropicamide 1.0% (with phenylephrine 2.5% if necessary), and the toric axis was measured at the slitlamp using a thin coaxial slit that was rotated until it overlapped the axis markings on the IOL. As well as clinical findings, patients were questioned regarding postoperative experiences of optical/visual disturbances (eg, arcs of light, halos, ghosting, day glare, night glare) and asked to rate their satisfaction with their level of uncorrected vision on a scale of 1 to 5 (1 Z not at all happy; 5 Z very happy). Surgeons used similar scales of 1 to 5 to rate ease of use of the Tecnis toric IOL calculator, ease of IOL implantation, achievement of target refraction, and overall satisfaction with the IOL. Surgeons documented these satisfaction scores for all eyes treated in the study. All data were entered into online case-report forms.
Data and Statistical Analysis Preoperative and postoperative J0 and J45 cylindrical vectors (refractive and keratometric) were computed using an Excel worksheet (2010 version, Microsoft Corp.) as follows20: J0 Z (cylinder/2)cos(2 axis); J45 Z (cylinder/2) sin(2 axis). SPSS for Windows software (version 18.0, SPSS, Inc.) was used for statistical analysis. Following a Kolmogorov-Smirnov test for normality, if parametric analysis was possible, a paired t test was performed to compare parameters between preoperative visits and postoperative visits. The Wilcoxon rank-sum test was used when data were not normally distributed to identify significant changes between preoperative values and postoperative values. A P value of 0.05 or less was considered statistically significant. Linear regression analysis was used to analyze the association between the intraoperative axis and the level of postoperative misalignment from the intended axis.
RESULTS Sixty-seven eyes of 60 patients were enrolled in the study. Postoperative determination of the axis of the IOL was performed in 61 eyes. Table 1 shows the patients’ demographics and preoperative data. Complications There were no intraoperative complications. One eye developed postoperative cystoid macular edema,
Table 1. Patient demographics and preoperative data. Parameter Patients (n) Eyes (n) Age (y) Mean G SD Range Sex, n (%) Male Female Preop refractive sphere (D) Mean G SD Range Preop refractive cylinder (D) Mean G SD Range Mean preop keratometry (D) G SD K1 (steep) K2 (flat) Axial length (mm) Mean G SD Range Mean IOL power (D) G SD Sphere Cylinder
Value 60 67 74.1 G 9.6 46, 92 22 (36.7) 38 (63.3) C0.20 G 2.54 7.00, C6.00 1.91 G 1.07 0.50, 4.75 45.24 G 1.96 42.91 G 1.90 23.48 G 1.10 21.60, 26.80 21.68 G 2.60 2.50 G 0.54
IOL Z intraocular lens
and a second patient had a hypersensitivity reaction to the topical antibiotic and steroid medication, which caused significant facial and ocular redness with a reduction in visual acuity. These patients did not attend the 4- to 8-week postoperative assessments because they were receiving alternative ophthalmic care; thus, they were not included in statistical analyses. However, the final CDVA was 0.1 logMAR in both eyes. Visual Acuity Table 2 shows the preoperative and postoperative refractive data, UDVA, and CDVA. At the 4- to 8-week visit, the mean UDVA was approximately 20/30, which improved slightly with refractive correction to approximately 20/25. The UDVA was 20/40 (0.3 logMAR) or better in 57 eyes (87.7%) (Figure 2). The postoperative CDVA was 20/40 (0.3 logMAR) or better in 62 eyes (95.4%), 20/30 (0.18 logMAR) or better in 50 eyes (76.9%), and 20/20 (0.0 logMAR) or better in 30 eyes (46.2%). Refraction Four to 8 weeks postoperatively, 62 eyes (95.4%) had a mean SE within G1.00 D of emmetropia. The level of refractive astigmatism decreased significantly
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Table 2. Mean preoperative and postoperative visual acuity and refraction.
Parameter Mean UDVA (logMAR) G SD Mean CDVA (logMAR) G SD Mean refractive sphere (D) G SD Mean SE (D) G SD Refractive cylinder (D) Mean G SD Range Keratometric cylinder (D) Mean G SD Range
Preop d
4 8 Wk Postop 0.15 G 0.17
P Value d
0.41 G 0.26
0.09 G 0.15 !.001*
0.20 G 2.54
0.24 G 0.66
.901
0.70 G 2.38
0.10 G 0.59
.034*
1.91 G 1.07 0.50, 4.75
0.67 G 0.54 !.001* 0.00, 2.25
2.21 G 0.91 0.78, 5.55
2.06 G 0.90 0.45, 5.55
.084
CDVA Z corrected distance visual acuity; SE Z spherical equivalent; UDVA Z uncorrected distance visual acuity *Statistically significant difference between preoperative and postoperative values at a Z 0.05 level
postoperatively (P ! .001; Table 2). Figure 3 shows the preoperative and postoperative J0 and J45 refractive cylinder vectors; the origin (0, 0) in Figure 3 represents an eye with no refractive astigmatism. Postoperatively, a concentration of data points around the origin is present compared with the preoperative spread. There was a significant reduction in the magnitude of the refractive J0 vector (P Z .002) postoperatively. The mean J45 vector did not change significantly (P Z .703); however, this would be expected given that the magnitude of the mean J45 vector was
Figure 2. Postoperative UDVA (65 eyes) (UDVA Z uncorrected distance visual acuity).
minimal preoperatively and postoperatively (0.04 D G 0.58 [SD] and 0.02 G 0.25 D, respectively), and not significantly different from zero (preoperative: P Z .528; postoperative: P Z .870). The keratometric J0 and J45 vectors did not change significantly between the preoperative and postoperative visits (J0: P Z .484; J45: P Z .982). Intraocular Lens Alignment No eye required additional surgery to rotate and reposition the IOL axis during the course of the study. The mean absolute IOL misalignment at the 4- to 8-week visit was 3.4 degrees (range 0 to 12 degrees). Nine eyes (14.7 %) had misalignment of more than 5 degrees; 1 eye (1.6%) had misalignment of more than 10 degrees. Linear regression analysis showed no significant association between the intraoperative axis position and postoperative alignment (P Z .27). Subjective Experience Patients Of the patients, 22 (37.9%) reported being very happy with their uncorrected vision postoperatively and 32 (55.2%) were happy (4 out of 5). Although all patients were at least moderately happy (3 out of 5) with their postoperative uncorrected vision, patient satisfaction was significantly associated with postoperative UDVA (y Z 4.834 – 2.481x; r Z 0.564; r2 Z 0.318; P ! .001). Optical or visual disturbances were rarely reported by patients attending the postoperative visit. Two patients (3%) reported daytime glare, both giving a score of 3 out of 5 for postoperative satisfaction with vision. The 4 ophthalmic surgeons described use of the toric online calculator as easy (4 out of 5) or very easy (5 out of 5) in 56 patients (96.6%). Regarding ease of IOL implantation, ease of alignment, and achievement of target refraction, surgeons scored 4 or 5 out of 5 in 55 patients (94.8%), 56 patients (96.5%), and 57 patients (98.3%), respectively. In terms
Surgeons
Figure 3. Preoperative and postoperative J0 and J45 cylindrical vectors (65 eyes).
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of overall refraction with the toric IOL, surgeons were satisfied or very satisfied in 54 patients (93.1%). DISCUSSION Use of toric IOLs during cataract surgery is one of several surgical options to correct corneal astigmatism and provide improved visual outcomes. The variability in healing responses associated with surgical flattening of the cornea results in a level of unpredictability regarding final outcomes.9,10 Thus, stable and effective toric IOLs implanted in the capsular bag during routine cataract surgery and requiring no modification of the cornea are an important advancement in modern cataract surgery. The present study, to our knowledge, is the first to describe application of the Tecnis toric IOL in a cohort of patients having routine cataract surgery. The results in the present study indicate that the Tecnis toric IOL is an effective means of treating corneal astigmatism of 0.75 D or more, with a statistically significant mean reduction in refractive astigmatism of 1.24 G 1.20 D. Postoperative refractive astigmatism ranged from 0.00 to 2.25 D (mean 0.67 G 0.54 D); the single eye with a 2.25 D postoperative cylindrical refraction had a preoperative 4.75 D refractive cylinder and 3.80 D of corneal toricity. Tecnis toric IOLs now come in cylinder powers of 1.00 D, 1.50 D, 2.25 D, 3.00 D, and 4.00 D (equivalent to 0.69 D, 1.03 D, 1.54 D, 2.06 D, and 2.74 D at the corneal plane, respectively). This range of cylinder powers allows application of the IOL in the majority of cataract patients with significant corneal astigmatism. The good standard of UDVA achieved in the study resulted in a high level of patient satisfaction with their uncorrected vision (93.1% of patients being happy or very happy), and a statistically significant association between these 2 factors was identified. The UDVA in the present study (mean 0.15 G 0.17 logMAR, with 88% of eyes having 20/40 or better) compares favorably with reports of outcomes with other toric IOLs. DeSilva et al.14 reported that 79% of eyes achieved 20/35 or better UDVA after implantation of the Microsil 6116TU (Humanoptics). Ali o et al.21 found a UDVA of at least 20/40 in 76% of eyes with moderate to high astigmatism implanted with the Acri.Comfort 646 TLC (Acri.Tec GmbH) and with various Acrysof toric models (Alcon Laboratories, Inc.). Bauer et al.17 found UDVA of at least 20/25 in 75% to 85% of eyes. Mendicute et al.13 identified a mean UDVA of 0.16 G 0.18 logMAR, with 93% of eyes achieving 20/40 or better, although the investigators excluded patients with macular degeneration and other ocular diseases that could reduce visual acuity. In the present study, which sought to evaluate
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the routine application of the Tecnis toric IOL, such exclusions were not made; all patients listed for routine cataract surgery with a minimum of 0.75 D of corneal astigmatism were eligible to participate; thus, the sample included several patients with early age-related macular degeneration and 1 patient with amblyopia (CDVA 0.3 logMAR in this eye). Postoperative rotational stability is vital to confer the best possible visual results with toric IOLs. The Tecnis toric IOL showed low levels of deviation from the target axis 4 to 8 weeks after implantation. Several mechanisms may result in undesirable postoperative IOL rotation. These include incomplete clearance of OVD, causing reduced friction between the haptics and the capsular bag,22 and early postoperative intraocular pressure fluctuations23; both are linked to rotational instability. Postoperative capsule shrinkage compresses IOL haptics and may cause rotation of certain IOL designs and materials. C-loop haptic IOLs were previously associated with high levels of postoperative rotation; Shimizu et al.1 reported more than 10 degrees of rotation in 41% of eyes 12 weeks postoperatively with a poly(methyl methacrylate) toric IOL. Although the Tecnis toric has C-loop haptics, its rotational stability is likely the result of factors related to its design and material. The 3-point fixation system (as the haptics are offset) and angled haptics that resist compression enable close contact between the IOL optic and posterior capsule.B Furthermore, the hydrophobic acrylic material can form bioactive bonds with fibronectin,24 an extracellular protein, resulting in a sandwich-like structure in which a single layer of LECs binds with the IOL and the posterior capsule.24,25 Such attachment may improve the rotational stability of the IOL and reduce the incidence of posterior capsule opacification. The low level of misalignment in the present study (mean 3.4 degrees; range 0 to 12 degrees) is in agreement with relatively recent reports of postoperative toric IOL stability. Mendicute et al.13 observed mean IOL rotation of 3.6 degrees in 30 eyes implanted with the Acrysof SN60T (Alcon Laboratories, Inc.) at 12 weeks, with 97% of the IOLs rotating less than 10 degrees. Chang26 compared the 4203TL/TF IOL (Staar) and the Acrysof SN60T at 1 month, finding a mean rotation of 5.6 G 8.49 degrees and 3.4 G 3.4 degrees, respectively. Entabi et al.15 report rotation of 3.4 degrees (range 0 to 12 degrees) at 16 weeks with the T-flex 623T IOL (Rayner). A limitation of the present study is that the follow-up period of 4 to 8 weeks did not permit long-term assessment of IOL stability. However, previously published studies indicate that most IOL rotation occurs in the early postoperative period, before fusion of the anterior and posterior capsules. Ahmed et al.16 and Kim et al.27
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identified minimal rotation of the Acrysof toric IOL, which is also composed of a hydrophobic acrylic material, between 1 month and 3 months postoperatively. No complications related to the new toric IOL model were observed in the present study. In summary, a significant reduction in refractive astigmatism resulting in good UDVA and high levels of patient and surgeon satisfaction were measured. The Tecnis toric IOL is based on the same platform as the Tecnis aspheric IOL and has a proprietary aspheric optic design to correct spherical aberration. The IOL is available in a broad range of cylinder powers, and data in the present study indicate good postoperative alignment with the intended axis. Hence, Tecnis toric IOL implantation appears to be an effective and predictable method of managing corneal astigmatism during routine cataract surgery. WHAT WAS KNOWN Approximately 60% of cataractous eyes have more than 0.75 D of corneal astigmatism. Stable and effective toric IOLs implanted into the capsular bag during routine cataract surgery are therefore an important requirement for modern cataract surgery, allowing correction of corneal astigmatism without modification of the cornea. WHAT THIS PAPER ADDS The new Tecnis toric 1-piece hydrophobic acrylic IOL effectively and predictably managed corneal astigmatism during routine cataract surgery. The IOL was associated with high levels of patient and surgeon satisfaction.
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8. Troutman RC, Swinger C. Relaxing incision for control of postoperative astigmatism following keratoplasty. Ophthalmic Surg 1980; 11:117–120 9. Nichamin LD. Astigmatism control. Ophthalmol Clin North Am 2006; 19(4):485–493 10. Carvalho MJ, Suzuki SH, Freitas LL, Branco BC, Shor P, €ffling-Lima AL. Limbal relaxing incisions to correct corneal Ho astigmatism during phacoemulsification. J Refract Surg 2007; 23:499–504 ~oz-Negrete FJ, Kim HRW, Morcillo-Laiz R, 11. Mingo-Botın D, Mun Rebolleda G, Oblanca N. Comparison of toric intraocular lenses and peripheral corneal relaxing incisions to treat astigmatism during cataract surgery. J Cataract Refract Surg 2010; 36:1700–1708 12. Till JS, Yoder PR Jr, Wilcox TK, Spielman JL. Toric intraocular lens implantation: 100 consecutive cases. J Cataract Refract Surg 2002; 28:295–301 s13. Mendicute J, Irigoyen C, Aramberri J, Ondarra A, Monte R. Foldable toric intraocular lens for astigmatism correction Mico in cataract patients. J Cataract Refract Surg 2008; 34:601–607 14. 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 15. 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 16. 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 2010; 36:609–616 17. Bauer NJC, de Vries NE, Webers CAB, Hendrikse F, Nuijts RMMA. Astigmatism management in cataract surgery with the AcrySof toric intraocular lens. J Cataract Refract Surg 2008; 34:1483–1488 18. Zhao H, Mainster MA. The effect of chromatic dispersion on pseudophakic optical performance. Br J Ophthalmol 2007; 91:1225–1229. Available at: http://www.ncbi.nlm.nih.gov/pmc/ articles/PMC1954934/pdf/1225.pdf. Accessed September 1, 2012 19. Buckhurst PJ, Wolffsohn JS, Davies LN, Naroo SA. Surgical correction of astigmatism during cataract surgery. Clin Exp Optom 2010; 93:409–418 20. Thibos LN, Wheeler W, Horner D. Power vectors: an application of Fourier analysis to the description and statistical analysis of refractive error. Optom Vis Sci 1997; 74:367–375. Available at: http://journals.lww.com/optvissci/Abstract/1997/06000/Power_ Vectors__An_Application_of_Fourier_Analysis.19.aspx. Accessed September 1, 2012 JL, Agdeppa MCC, Pongo VC, El Kady B. Microincision cat21. Alio aract surgery with toric intraocular lens implantation for correcting moderate and high astigmatism: pilot study. J Cataract Refract Surg 2010; 36:44–52 22. Myers TD, Olson RJ. Comparison of the effects of viscoelastic agents on clinical properties of the Unfolder lens injection system. J Cataract Refract Surg 1999; 25:953–958 23. Pereira FAS, Milverton EJ, Coroneo MT. Miyake-Apple study of the rotational stability of the Acrysof toric intraocular lens after experimental eye trauma. Eye 2010; 24:776 378. Available at: http://www.nature.com/eye/journal/v24/n2/pdf/ eye2009150a.pdf. Accessed September 1, 2012 € nen R, Pihlajaniemi T. Adhesion of sol24. Linnola RJ, Sund M, Ylo uble fibronectin, vitronectin, and collagen type IV to intraocular lens materials. J Cataract Refract Surg 2003; 29:146–152 25. Linnola RJ, Werner L, Pandey SK, Escobar-Gomez M, Znoiko SL, Apple DJ. Adhesion of fibronectin, vitronectin,
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laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 1: histological sections. J Cataract Refract Surg 2000; 26:1792–1806 26. 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 27. Kim MH, Chung T-Y, Chung E-S. Long-term efficacy and rotational stability of AcrySof toric intraocular lens implantation in cataract surgery. Korean J Ophthalmol 2010; 24:207–212. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/ PMC2916101/pdf/kjo-24-207.pdf. Accessed September 1, 2012
B. Nixon DR, “Clinical Evaluation of an Investigational 1-Piece Acrylic Monofocal IOL,” presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Chicago, Illinois, USA, April 2008
OTHER CITED MATERIAL A. Abbott Medical Optics. AMO IOL calculator platform. Available at: www.TecnisToricCalc.com. Accessed September 1, 2012
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First author: Amy L. Sheppard, PhD School of Life and Health Sciences, Aston University, Birmingham, United Kingdom