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Rotation and decentration of an undersized plate-haptic trifocal toric intraocular lens in an eye with moderate myopia
CASE REPORT
Rotation and decentration of an undersized plate-haptic trifocal toric intraocular lens in an eye with moderate myopia Bert C. Giers, MD, Ramin Khoramnia, MD, Lea F. Weber, MD, Tamer Tandogan, MD, Gerd U. Auffarth, MD, PhD
We present the case of a 56-year-old woman with moderate myopia and bilateral cataract who had cataract extraction and intraocular lens (IOL) implantation. Due to the patient’s desire for spectacle independence, a trifocal IOL with toric correction for astigmatism was implanted. During the follow-up, it became obvious that the implanted IOL had rotated and tilted due to insufficient fixation in the large capsular bag of the myopic eye. An IOL explantation was therefore performed, and the original IOL was exchanged for a bifocal toric IOL with a larger overall diameter. Stable fixation of the IOL in the capsular bag was achieved, and after surgery in the second eye, the patient recovered good bilateral vision. This case illustrates the need for careful selection of IOL diameter and sizing even in patients with moderate myopia due to the potentially larger ocular dimensions in these patients. Financial Disclosures: Drs. Auffarth, Tandogan, and Khoramnia received research grants, travel expenses, and lecture fees from Abbott Medical Optics, Inc. and Carl Zeiss Meditec AG. Drs. Giers and Weber have no financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2016; 42:489–493 Q 2016 ASCRS and ESCRS Online Video
Rising expectations about the refractive outcome in patients having cataract surgery and an increasing demand for spectacle independence present a challenge to surgical techniques and the choice of which intraocular lens (IOL) to use. Advances in IOL development have opened up the possibility of correcting presbyopia or concomitant ametropia as well as treating cataract. Multifocal IOLs separate the incoming light into 2 or more focal points to provide distance,
Submitted: December 15, 2015. Final revision submitted: January 13, 2016. Accepted: January 19, 2016. From the Department of Ophthalmology (Auffarth, Giers, Tandogan, Khoramnia, Weber), the International Vision Correction Research Center, and the David J. Apple International Laboratory for Ocular Pathology (Auffarth, Giers, Tandogan, Khoramnia), University of Heidelberg, Heidelberg, Germany. Corresponding author: Gerd U. Auffarth, MD, PhD, University Eye Clinic Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. E-mail: [email protected]. Q 2016 ASCRS and ESCRS Published by Elsevier Inc.
intermediate, and near vision without additional correction through spectacles. The use of multifocal IOLs has become increasingly popular for patients with planned cataract surgery. However, preexisting corneal astigmatism is likely to make postoperative visual outcomes unsatisfactory.1 Surgical techniques such as selective positioning of the main clear corneal incision (on-axis incision), limbal relaxing incisions, or opposite clear corneal incisions represent ways of treating preexisting corneal astigmatism, but will usually not suffice to treat high astigmatism adequately and do not always offer predictable outcomes.2–4 A staged procedure with cataract surgery and subsequent correction of astigmatism with the excimer laser is another possibility, but this is limited to patients with sufficient corneal thickness and poses the risks for an additional surgical procedure. One frequently encountered problem after such a procedure is the dry-eye syndrome, which might require long-term use of artificial tear substitutes.5 Toric IOLs have become an increasingly important alternative for simple and predictable treatment http://dx.doi.org/10.1016/j.jcrs.2016.02.001 0886-3350
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of preexisting corneal astigmatism.6–8 Stable and rotation-free fixation of toric IOLs is important for a satisfactory postoperative visual outcome.9 Theoretical calculations show that approximately 3.3% of cylindrical power is lost for each degree of off-axis rotation by a toric IOL, leading to an increase in net astigmatism if the IOL is rotated more than 30 degrees off axis.10 Rotational stability is primarily influenced by the interaction between the IOL and the capsular bag. Insufficient haptic size, especially in plate-haptic IOLs, is considered the key factor in early postoperative rotational instability.9,11 Postoperative capsule fibrosis and capsular bag shrinkage have been identified as possible causes for late postoperative IOL rotation.11 Abnormal ocular dimensions in ametropia may also affect capsule fixation of implanted IOLs. In myopia, increased axial length (AL) is likely accompanied by increased capsular bag size,9,12 making it difficult to achieve rotational stability for IOLs with a small overall diameter or small haptics. Although this may not be problematic in monofocal IOL implantation, postoperative outcomes may be severely affected in IOLs that depend on strict rotational stability such as toric IOLs or IOLs with an added near-field segment. We present a case in which a trifocal toric IOL was implanted in a myopic eye, but turned out to be too small to achieve stable fixation in the capsular bag and had to be explanted and exchanged for an alternative multifocal toric IOL model with a larger overall diameter. CASE REPORT A 56-year-old woman with preexisting myopia presented to our clinic with bilateral corticonuclear cataract advanced in the left eye but less advanced in the right eye. The uncorrected distance visual acuity (UDVA) was 20/100 in the right eye and 20/200 in the left eye, and the corrected distance visual acuity was 20/32 with 5.75 and 20/80 with 6.5 2.0 133, respectively (Table 1). Preoperative biometry was performed using partial coherence interferometry (IOLMaster, Carl Zeiss Meditec AG), measuring an AL of 26.07 mm in the right eye and 25.99 mm in the left eye and Table 1. Visual acuity in the left eye at baseline and postoperatively.
Measurement UDVA UNVA SR CDVA
Preoperatively 20/200 d 6.5 2.0 133 20/80
After 1st Procedure
After 2nd Procedure
20/50 20/63 Plano NI
20/25 20/32 Plano NI
CDVA Z corrected distance visual acuity; NI Z no improvement with corrective lenses; SR Z subjective refraction; UDVA Z uncorrected distance visual acuity; UNVA Z uncorrected near visual acuity (at 40 cm).
a cylinder of 1.77 173 in the right eye and 1.77 178 in the left eye (Table 2). The patient had had satisfactory vision with bifocal contact lenses and asked specifically for implantation of a trifocal IOL to retain spectacle independence. The left eye was scheduled first for surgery as an outpatient procedure under general anesthesia. Femtosecond laser–assisted phacoemulsification and implantation of an AT LISA tri toric 939 MP IOL (Carl Zeiss Meditec AG) with C12.75 C1.5 87 were performed. The single-piece foldable hydrophilic acrylic IOL has a plate-haptic design with an optic diameter of 6.0 mm and overall diameter of 11.0 mm. It has a trifocal diffractive aspheric bitoric design and provides a near addition (add) of C3.33 D and an intermediate add of C1.66 D calculated at the IOL plane. Although intraoperatively the capsular bag appeared somewhat large, the IOL seemed to be stably fixated. When the patient presented for the first postoperative examination the next morning, the UDVA was 20/50 and the uncorrected near visual acuity (UNVA) (measured at 40 cm) was 20/63. On slitlamp examination, the IOL appeared to be decentered and tilted to temporal inferior, with the axis rotated approximately 30 degrees clockwise (Figure 1). In discussion with the patient, it was decided to explant the IOL and replace it with an IOL with larger haptics. The surgery was scheduled for 3 days after the first intervention. The IOL was successfully explanted through the original corneal incision. In its place, a Tecnis ZMT150 IOL (Abbott Medical Optics, Inc.) with C13.5 C1.5 87 (with a near add of C4.0 D) was implanted in the capsular bag (Video 1, available at http://jcrsjournal.org). The singlepiece hydrophobic acrylic toric IOL has an optic diameter of 6.0 mm and 2 modified C haptics with an overall diameter of 13.0 mm. It has a bifocal bitoric diffractive aspheric design and offers a near add of C4.00 D calculated at the IOL plane. Due to the larger haptic diameter (13.0 mm compared with 11.0 mm), stable fixation in the capsular bag could be achieved. The patient recovered without further complications. The multifocal IOL remained centered with the axis in place. Postoperative UDVA in the left eye was 20/25 and UNVA was 20/32. Additional corrective lenses did not yield further improvement. Surgery was performed 1 week later in the second (right) eye, and the same IOL model was implanted; ie, a Tecnis ZMT150 IOL with C13.0 C1.5 80 (with a near add of C4.0 D). Postoperatively, the UDVA and UNVA in the right eye were 20/25 and 20/32, respectively. Additional corrective lenses did not yield any improvement.
DISCUSSION Accurate axial alignment and postoperative rotational stability of toric IOLs are critical for the efficacy of astigmatism correction. Several risk factors that affect rotational stability have been established; these include IOL design and diameter, axis of IOL alignment, AL, capsulorhexis size, capsular bag diameter, and capsular bag shrinkage and fibrosis.9,12,13 Studies have shown that single-piece plate-haptic designs tend to have a higher degree of early postoperative rotation but retain their position more stably once capsule fusion has occurred.9,11 Loop-haptic designs, on the other hand, tend to have less early
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Table 2. Preoperative biometric data using partial coherence interferometry. Eye Right Left
AL (mm)
R1 (mm/D/ )
R2 (mm/D/ )
R/SE (mm/D)
26.07 (SNR Z 301.8) 25.99 (SNR Z 85.7)
7.77/42.73 173 7.78/42.67 178
7.46/44.50 83 7.47/44.44 88
7.62/43.61 7.63/43.56
Cylinder 1.77 173 1.77 178
ACD (mm) 3.52 3.98
ACD Z anterior chamber depth; AL Z axial length; R Z corneal radius; SE Z spherical equivalent; SNR Z signal-to-noise ratio.
rotational misalignment but are more affected by late rotation. This is thought to be due to interactions between the IOL and capsular bag: The fusion of the anterior and posterior sheets, which usually starts at the wide angle of the C-shaped haptic, leaves room for counterclockwise rotation.11 Capsular bag shrinkage, on the other hand, is thought to invoke torque on the haptics, causing the fused bag to separate or the optic to turn independently from the haptic, both of which induce clockwise rotation.11,12 Early rotational instability appears to be primarily influenced by IOL size, with bigger overall diameters or larger haptics leading to better initial fixation of the IOL in the capsular bag.9 However, capsular bag dimensions vary interindividually and are difficult to assess preoperatively. The postmortem mean diameter of an empty capsular bag is reported to lie in the range of 10.0 mm to 10.8 mm.14,15 Because of capsule apposition and zonular fiber relaxation, the diameter of the capsular bag increases slightly (by approximately 0.2 mm) on lens removal.14 A significant correlation has been demonstrated between capsular bag size and AL as well as other biometric variables such as corneal power.15 A correlation has also been shown between AL and early IOL rotation, which is thought to be due to larger capsular bag dimensions in longer myopic eyes.12 However, the final effect of AL on IOL rotation is unclear. Recently, Klamann et al.16 reported no significant correlation between toric IOL rotation and
AL. However, they examined only a modern singlepiece loop-haptic IOL design with a 13.0 mm overall haptic length. In addition, they do not state the range in AL and the ratio of highly myopic patients in their study. Miyake et al.17 reported severe rotation of the same IOL model in 6 highly myopic eyes with ALs between 25.41 mm and 31.01 mm. Sun et al.18 reported a high incidence of severe early IOL misalignment in myopic patients receiving plate-haptic toric IOLs with a short overall diameter (10.8 mm). The overall length of the IOL haptic is therefore considered to be crucial for early rotational stability, especially in plate-haptic designs. Because the capsular bag dimensions cannot be reliably measured prior to surgery whereas AL is routinely measured for IOL power calculations, AL is often used as a surrogate parameter for capsular bag size. From their measurements of capsular bag size in patients with implantation of a capsular tension ring, Vass et al.15 proposed a formula by which capsular bag size can be predicted based on AL and, if applicable, corneal power. The formula is stated to work well in eyes with an AL shorter than 25.0 mm but to be of limited accuracy in highly myopic eyes with ALs longer than 25.0 mm. Furthermore, it leaves too much variability for reliable prediction of capsular bag size. Vass et al., however, suggest a cutoff value for the predicted (ie, calculated) capsular bag size of 10.3 mm that correctly classified all eyes with a very large actual capsular bag diameter (O10.7 mm) and
Figure 1. Intraoperative photographs showing preoperative IOL position (A) and IOL movement within the capsular bag on irrigation/aspiration (B). J CATARACT REFRACT SURG - VOL 42, MARCH 2016
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CASE REPORT: DECENTRATION OF AN UNDERSIZED TRIFOCAL IOL
most eyes (77%) with a very small capsular bag diameter (!10.1 mm), and this value could be used to preselect patients with potentially large capsular bags to implant a larger haptic IOL to prevent undersizing. To our knowledge, this formula has not been implemented in routine preoperative screening of patients having toric IOL implantation. The significance of the formula may have been attenuated by the introduction of larger plate-haptic IOLs (10.5 to 10.8 mm plate-haptic designs in the late 1990s compared with 11.0 mm in modern plate-haptic toric IOLs) with advanced haptic design. Modern toric IOLs generally show good overall rotational stability.6 Nevertheless, our case shows that underestimating the capsular bag diameter in myopic eyes can lead to severe early IOL rotation, making an IOL exchange necessary. Although the initially implanted platehaptic IOL in our patient had an overall diameter of 11.0 mm, it proved to be too small to be stably fixated in the capsular bag and showed severe rotation and tilt immediately postoperatively, significantly attenuating the predicted visual outcome. When retrospectively calculating the predicted capsular bag diameter using the Vass et al. formula and the preoperatively derived biometric data from our patient, one arrives at a predicted capsular bag diameter of 10.4 mm, suggesting that the IOL size of 11.0 mm would have been sufficient. However, it must be stressed that the formula was not intended for preoperative screening and does show only weak correlation between AL and measured capsular bag size in large eyes with an AL longer than 25.0 mm. In our case, the initially implanted trifocal toric IOL was exchanged for a bifocal toric IOL primarily for the haptic design and the larger overall diameter. To our knowledge, the optic designs of the 2 IOL models have not been directly compared. From optical bench measurements, one would expect an improved intermediate distance visual acuity with the trifocal IOL without significant deterioration of far and near visual acuity.19 Functional assessment of 56 eyes of 28 patients implanted with the AT LISA tri toric 939 MP showed postoperative monocular UDVA, uncorrected intermediate visual acuity (UIVA), and UNVA of 0.13 logMAR G 0.15 (SD), 0.08 G 0.15 logMAR, and 0.13 G 0.18 logMAR, respectively.8 In another study of the Tecnis ZMT in 57 eyes of 38 patients,20 postoperative UDVA, UIVA, and UNVA were 0.12 G 0.16 logMAR, 0.21 G 0.13 logMAR, and 0.10 G 0.14 logMAR, respectively. Further investigation of the rotational stability of toric IOLs in myopic eyes is necessary before general recommendations for IOL sizing can be made. Advances in anterior segment imaging (eg, ultrasound biomicroscopy and optical coherence tomography),
may provide better prediction of capsular bag dimensions in the future. In the meantime, however, careful patient screening and IOL selection with regard to AL and capsular bag size in myopic patients are important to avoid postoperative complications due to IOL rotation. As a general rule, one might opt for loop-haptic IOLs with a 13.0 mm overall diameter in this subset of patients. In conclusion, even in eyes with moderate myopia, the capsular bag diameter may be large, leading to insufficient IOL fixation and poor postoperative outcome. If care is taken in patient selection and preoperative assessment, toric IOLs provide good postoperative visual outcome in patients with abnormal optical dimensions due to myopia. REFERENCES 1. Auffarth GU, Rabsilber TM. Torische Hinterkammerlinsen nach Kataraktoperation und refraktivem Linsenaustausch [Toric IOLs after cataract surgery and refractive lens exchange]. Ophthalmologe 2007; 104:1024–1031 2. 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 3. Lam DKT, Chow VWS, Ye C, Ng PK-F, Wang Z, Jhanji V. Comparative evaluation of aspheric toric intraocular lens implantation and limbal relaxing incisions in eyes with cataracts and %3 dioptres of astigmatism. Br J Ophthalmol 2015 Jun 18. [Epub ahead of print] 4. Lee BS, Lindstrom RL, Reeves SW, Hardten DR. Modern management of astigmatism. Int Ophthalmol Clin 2013; 53:65–78 5. Denoyer A, Landman E, Trinh L, Faure J-F, Auclin F, Baudouin C. Dry eye disease after refractive surgery; comparative outcomes of small incision lenticule extraction versus LASIK. Ophthalmology 2014; 122:669–676 6. Visser N, Bauer NJC, Nuijts RMMA. Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications. J Cataract Refract Surg 2013; 39:624–637 7. Khoramnia R, Fitting A, Rabsilber TM, Auffarth GU, Holzer MP. Postoperative Ergebnisse nach Implantation einer torischen, as€rischen Intraokularlinse [Postoperative results after implanpha tation of a toric, aspheric intraocular lens]. Klin Monatsbl Augenheilkd 2015; 232:867–873 8. Kretz FT, Breyer D, Klabe K, Hagen P, Kaymak H, Koss MJ, Gerl M, Mueller M, Gerl RH, Auffarth GU. Clinical outcomes after implantation of a trifocal toric intraocular lens. J Refract Surg 2015; 31:504–510. Available at: http://www.healio.com/ophthalmology/ journals/jrs/2015-8-31-8/%7Be12f84f5-cfc3-4fea-986e-b252d 0c58e1f%7D/clinical-outcomes-after-implantation-of-a-trifocaltoric-intraocular-lens.pdf. Accessed January 20, 2015 9. Chang DF. Early rotational stability of the longer Staar toric intraocular lens; fifty consecutive cases. J Cataract Refract Surg 2003; 29:935–940 10. Sanders DR, Grabow HB, Shepherd J. The toric IOL. In: Gills JP, Martin RG, Sanders DR, eds, Sutureless Cataract Surgery; an Evolution Toward Minimally Invasive Technique. Thorofare, NJ, Slack, 1992; 183–197 11. Patel CK, Ormonde S, Rosen PH, Bron AJ. Postoperative intraocular lens rotation: a randomized comparison of plate and loop
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12.
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haptic implants. Ophthalmology 1999; 106:2190–2195; discussion by DJ Apple, 2196 Shah GD, Praveen MR, Vasavada AR, Vasavada VA, Rampal G, Shastry LR. Rotational stability of a toric intraocular lens: influence of axial length and alignment in the capsular bag. J Cataract Refract Surg 2012; 38:54–59 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 Vasavada A, Singh R. Relationship between lens and capsular bag size. J Cataract Refract Surg 1998; 24:547–551 Vass C, Menapace R, Schmetterer K, Findl O, Rainer G, Steineck I. Prediction of pseudophakic capsular bag diameter based on biometric variables. J Cataract Refract Surg 1999; 25:1376–1381 Klamann MKJ, Von Sonnleithner C, Gonnermann J, Maier AKB, Torun N, Bertelmann E. Influence of biometric parameters on rotational stability of toric IOLs. Eur J Ophthalmol 2013; 23:836–840 Miyake T, Kamiya K, Amano R, Iida Y, Tsunehiro S, Shimizu K. Long-term clinical outcomes of toric intraocular lens implantation in cataract cases with preexisting astigmatism. J Cataract Refract Surg 2014; 40:1654–1660
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18. Sun X-Y, Vicary D, Montgomery P, Griffiths M. Toric intraocular lenses for correcting astigmatism in 130 eyes. Ophthalmology 2000; 107:1776–1781; discussion by RM Kershner, 1781–1782 19. Gatinel D, Houbrechts Y. Comparison of bifocal and trifocal diffractive and refractive intraocular lenses using an optical bench. J Cataract Refract Surg 2013; 39:1093–1099 € ller M, Gerl M, 20. Kretz FTA, Bastelica A, Carreras H, Ferreira T, Mu Gerl R, Saeed M, Schmickler S, Auffarth GU. Clinical outcomes and surgeon assessment after implantation of a new diffractive multifocal toric intraocular lens. Br J Ophthalmol 2015; 99:405–411
J CATARACT REFRACT SURG - VOL 42, MARCH 2016
First author: Bert C. Giers, MD Department of Ophthalmology, International Vision Correction Research Center, University of Heidelberg, Heidelberg, Germany
Rotation and decentration of an undersized plate-haptic trifocal toric intraocular lens in an eye with moderate myopia Bert C. Giers, MD, Ramin Khoramnia, MD, Lea F. Weber, MD, Tamer Tandogan, MD, Gerd U. Auffarth, MD, PhD
We present the case of a 56-year-old woman with moderate myopia and bilateral cataract who had cataract extraction and intraocular lens (IOL) implantation. Due to the patient’s desire for spectacle independence, a trifocal IOL with toric correction for astigmatism was implanted. During the follow-up, it became obvious that the implanted IOL had rotated and tilted due to insufficient fixation in the large capsular bag of the myopic eye. An IOL explantation was therefore performed, and the original IOL was exchanged for a bifocal toric IOL with a larger overall diameter. Stable fixation of the IOL in the capsular bag was achieved, and after surgery in the second eye, the patient recovered good bilateral vision. This case illustrates the need for careful selection of IOL diameter and sizing even in patients with moderate myopia due to the potentially larger ocular dimensions in these patients. Financial Disclosures: Drs. Auffarth, Tandogan, and Khoramnia received research grants, travel expenses, and lecture fees from Abbott Medical Optics, Inc. and Carl Zeiss Meditec AG. Drs. Giers and Weber have no financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2016; 42:489–493 Q 2016 ASCRS and ESCRS Online Video
Rising expectations about the refractive outcome in patients having cataract surgery and an increasing demand for spectacle independence present a challenge to surgical techniques and the choice of which intraocular lens (IOL) to use. Advances in IOL development have opened up the possibility of correcting presbyopia or concomitant ametropia as well as treating cataract. Multifocal IOLs separate the incoming light into 2 or more focal points to provide distance,
Submitted: December 15, 2015. Final revision submitted: January 13, 2016. Accepted: January 19, 2016. From the Department of Ophthalmology (Auffarth, Giers, Tandogan, Khoramnia, Weber), the International Vision Correction Research Center, and the David J. Apple International Laboratory for Ocular Pathology (Auffarth, Giers, Tandogan, Khoramnia), University of Heidelberg, Heidelberg, Germany. Corresponding author: Gerd U. Auffarth, MD, PhD, University Eye Clinic Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. E-mail: [email protected]. Q 2016 ASCRS and ESCRS Published by Elsevier Inc.
intermediate, and near vision without additional correction through spectacles. The use of multifocal IOLs has become increasingly popular for patients with planned cataract surgery. However, preexisting corneal astigmatism is likely to make postoperative visual outcomes unsatisfactory.1 Surgical techniques such as selective positioning of the main clear corneal incision (on-axis incision), limbal relaxing incisions, or opposite clear corneal incisions represent ways of treating preexisting corneal astigmatism, but will usually not suffice to treat high astigmatism adequately and do not always offer predictable outcomes.2–4 A staged procedure with cataract surgery and subsequent correction of astigmatism with the excimer laser is another possibility, but this is limited to patients with sufficient corneal thickness and poses the risks for an additional surgical procedure. One frequently encountered problem after such a procedure is the dry-eye syndrome, which might require long-term use of artificial tear substitutes.5 Toric IOLs have become an increasingly important alternative for simple and predictable treatment http://dx.doi.org/10.1016/j.jcrs.2016.02.001 0886-3350
489
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CASE REPORT: DECENTRATION OF AN UNDERSIZED TRIFOCAL IOL
of preexisting corneal astigmatism.6–8 Stable and rotation-free fixation of toric IOLs is important for a satisfactory postoperative visual outcome.9 Theoretical calculations show that approximately 3.3% of cylindrical power is lost for each degree of off-axis rotation by a toric IOL, leading to an increase in net astigmatism if the IOL is rotated more than 30 degrees off axis.10 Rotational stability is primarily influenced by the interaction between the IOL and the capsular bag. Insufficient haptic size, especially in plate-haptic IOLs, is considered the key factor in early postoperative rotational instability.9,11 Postoperative capsule fibrosis and capsular bag shrinkage have been identified as possible causes for late postoperative IOL rotation.11 Abnormal ocular dimensions in ametropia may also affect capsule fixation of implanted IOLs. In myopia, increased axial length (AL) is likely accompanied by increased capsular bag size,9,12 making it difficult to achieve rotational stability for IOLs with a small overall diameter or small haptics. Although this may not be problematic in monofocal IOL implantation, postoperative outcomes may be severely affected in IOLs that depend on strict rotational stability such as toric IOLs or IOLs with an added near-field segment. We present a case in which a trifocal toric IOL was implanted in a myopic eye, but turned out to be too small to achieve stable fixation in the capsular bag and had to be explanted and exchanged for an alternative multifocal toric IOL model with a larger overall diameter. CASE REPORT A 56-year-old woman with preexisting myopia presented to our clinic with bilateral corticonuclear cataract advanced in the left eye but less advanced in the right eye. The uncorrected distance visual acuity (UDVA) was 20/100 in the right eye and 20/200 in the left eye, and the corrected distance visual acuity was 20/32 with 5.75 and 20/80 with 6.5 2.0 133, respectively (Table 1). Preoperative biometry was performed using partial coherence interferometry (IOLMaster, Carl Zeiss Meditec AG), measuring an AL of 26.07 mm in the right eye and 25.99 mm in the left eye and Table 1. Visual acuity in the left eye at baseline and postoperatively.
Measurement UDVA UNVA SR CDVA
Preoperatively 20/200 d 6.5 2.0 133 20/80
After 1st Procedure
After 2nd Procedure
20/50 20/63 Plano NI
20/25 20/32 Plano NI
CDVA Z corrected distance visual acuity; NI Z no improvement with corrective lenses; SR Z subjective refraction; UDVA Z uncorrected distance visual acuity; UNVA Z uncorrected near visual acuity (at 40 cm).
a cylinder of 1.77 173 in the right eye and 1.77 178 in the left eye (Table 2). The patient had had satisfactory vision with bifocal contact lenses and asked specifically for implantation of a trifocal IOL to retain spectacle independence. The left eye was scheduled first for surgery as an outpatient procedure under general anesthesia. Femtosecond laser–assisted phacoemulsification and implantation of an AT LISA tri toric 939 MP IOL (Carl Zeiss Meditec AG) with C12.75 C1.5 87 were performed. The single-piece foldable hydrophilic acrylic IOL has a plate-haptic design with an optic diameter of 6.0 mm and overall diameter of 11.0 mm. It has a trifocal diffractive aspheric bitoric design and provides a near addition (add) of C3.33 D and an intermediate add of C1.66 D calculated at the IOL plane. Although intraoperatively the capsular bag appeared somewhat large, the IOL seemed to be stably fixated. When the patient presented for the first postoperative examination the next morning, the UDVA was 20/50 and the uncorrected near visual acuity (UNVA) (measured at 40 cm) was 20/63. On slitlamp examination, the IOL appeared to be decentered and tilted to temporal inferior, with the axis rotated approximately 30 degrees clockwise (Figure 1). In discussion with the patient, it was decided to explant the IOL and replace it with an IOL with larger haptics. The surgery was scheduled for 3 days after the first intervention. The IOL was successfully explanted through the original corneal incision. In its place, a Tecnis ZMT150 IOL (Abbott Medical Optics, Inc.) with C13.5 C1.5 87 (with a near add of C4.0 D) was implanted in the capsular bag (Video 1, available at http://jcrsjournal.org). The singlepiece hydrophobic acrylic toric IOL has an optic diameter of 6.0 mm and 2 modified C haptics with an overall diameter of 13.0 mm. It has a bifocal bitoric diffractive aspheric design and offers a near add of C4.00 D calculated at the IOL plane. Due to the larger haptic diameter (13.0 mm compared with 11.0 mm), stable fixation in the capsular bag could be achieved. The patient recovered without further complications. The multifocal IOL remained centered with the axis in place. Postoperative UDVA in the left eye was 20/25 and UNVA was 20/32. Additional corrective lenses did not yield further improvement. Surgery was performed 1 week later in the second (right) eye, and the same IOL model was implanted; ie, a Tecnis ZMT150 IOL with C13.0 C1.5 80 (with a near add of C4.0 D). Postoperatively, the UDVA and UNVA in the right eye were 20/25 and 20/32, respectively. Additional corrective lenses did not yield any improvement.
DISCUSSION Accurate axial alignment and postoperative rotational stability of toric IOLs are critical for the efficacy of astigmatism correction. Several risk factors that affect rotational stability have been established; these include IOL design and diameter, axis of IOL alignment, AL, capsulorhexis size, capsular bag diameter, and capsular bag shrinkage and fibrosis.9,12,13 Studies have shown that single-piece plate-haptic designs tend to have a higher degree of early postoperative rotation but retain their position more stably once capsule fusion has occurred.9,11 Loop-haptic designs, on the other hand, tend to have less early
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CASE REPORT: DECENTRATION OF AN UNDERSIZED TRIFOCAL IOL
Table 2. Preoperative biometric data using partial coherence interferometry. Eye Right Left
AL (mm)
R1 (mm/D/ )
R2 (mm/D/ )
R/SE (mm/D)
26.07 (SNR Z 301.8) 25.99 (SNR Z 85.7)
7.77/42.73 173 7.78/42.67 178
7.46/44.50 83 7.47/44.44 88
7.62/43.61 7.63/43.56
Cylinder 1.77 173 1.77 178
ACD (mm) 3.52 3.98
ACD Z anterior chamber depth; AL Z axial length; R Z corneal radius; SE Z spherical equivalent; SNR Z signal-to-noise ratio.
rotational misalignment but are more affected by late rotation. This is thought to be due to interactions between the IOL and capsular bag: The fusion of the anterior and posterior sheets, which usually starts at the wide angle of the C-shaped haptic, leaves room for counterclockwise rotation.11 Capsular bag shrinkage, on the other hand, is thought to invoke torque on the haptics, causing the fused bag to separate or the optic to turn independently from the haptic, both of which induce clockwise rotation.11,12 Early rotational instability appears to be primarily influenced by IOL size, with bigger overall diameters or larger haptics leading to better initial fixation of the IOL in the capsular bag.9 However, capsular bag dimensions vary interindividually and are difficult to assess preoperatively. The postmortem mean diameter of an empty capsular bag is reported to lie in the range of 10.0 mm to 10.8 mm.14,15 Because of capsule apposition and zonular fiber relaxation, the diameter of the capsular bag increases slightly (by approximately 0.2 mm) on lens removal.14 A significant correlation has been demonstrated between capsular bag size and AL as well as other biometric variables such as corneal power.15 A correlation has also been shown between AL and early IOL rotation, which is thought to be due to larger capsular bag dimensions in longer myopic eyes.12 However, the final effect of AL on IOL rotation is unclear. Recently, Klamann et al.16 reported no significant correlation between toric IOL rotation and
AL. However, they examined only a modern singlepiece loop-haptic IOL design with a 13.0 mm overall haptic length. In addition, they do not state the range in AL and the ratio of highly myopic patients in their study. Miyake et al.17 reported severe rotation of the same IOL model in 6 highly myopic eyes with ALs between 25.41 mm and 31.01 mm. Sun et al.18 reported a high incidence of severe early IOL misalignment in myopic patients receiving plate-haptic toric IOLs with a short overall diameter (10.8 mm). The overall length of the IOL haptic is therefore considered to be crucial for early rotational stability, especially in plate-haptic designs. Because the capsular bag dimensions cannot be reliably measured prior to surgery whereas AL is routinely measured for IOL power calculations, AL is often used as a surrogate parameter for capsular bag size. From their measurements of capsular bag size in patients with implantation of a capsular tension ring, Vass et al.15 proposed a formula by which capsular bag size can be predicted based on AL and, if applicable, corneal power. The formula is stated to work well in eyes with an AL shorter than 25.0 mm but to be of limited accuracy in highly myopic eyes with ALs longer than 25.0 mm. Furthermore, it leaves too much variability for reliable prediction of capsular bag size. Vass et al., however, suggest a cutoff value for the predicted (ie, calculated) capsular bag size of 10.3 mm that correctly classified all eyes with a very large actual capsular bag diameter (O10.7 mm) and
Figure 1. Intraoperative photographs showing preoperative IOL position (A) and IOL movement within the capsular bag on irrigation/aspiration (B). J CATARACT REFRACT SURG - VOL 42, MARCH 2016
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most eyes (77%) with a very small capsular bag diameter (!10.1 mm), and this value could be used to preselect patients with potentially large capsular bags to implant a larger haptic IOL to prevent undersizing. To our knowledge, this formula has not been implemented in routine preoperative screening of patients having toric IOL implantation. The significance of the formula may have been attenuated by the introduction of larger plate-haptic IOLs (10.5 to 10.8 mm plate-haptic designs in the late 1990s compared with 11.0 mm in modern plate-haptic toric IOLs) with advanced haptic design. Modern toric IOLs generally show good overall rotational stability.6 Nevertheless, our case shows that underestimating the capsular bag diameter in myopic eyes can lead to severe early IOL rotation, making an IOL exchange necessary. Although the initially implanted platehaptic IOL in our patient had an overall diameter of 11.0 mm, it proved to be too small to be stably fixated in the capsular bag and showed severe rotation and tilt immediately postoperatively, significantly attenuating the predicted visual outcome. When retrospectively calculating the predicted capsular bag diameter using the Vass et al. formula and the preoperatively derived biometric data from our patient, one arrives at a predicted capsular bag diameter of 10.4 mm, suggesting that the IOL size of 11.0 mm would have been sufficient. However, it must be stressed that the formula was not intended for preoperative screening and does show only weak correlation between AL and measured capsular bag size in large eyes with an AL longer than 25.0 mm. In our case, the initially implanted trifocal toric IOL was exchanged for a bifocal toric IOL primarily for the haptic design and the larger overall diameter. To our knowledge, the optic designs of the 2 IOL models have not been directly compared. From optical bench measurements, one would expect an improved intermediate distance visual acuity with the trifocal IOL without significant deterioration of far and near visual acuity.19 Functional assessment of 56 eyes of 28 patients implanted with the AT LISA tri toric 939 MP showed postoperative monocular UDVA, uncorrected intermediate visual acuity (UIVA), and UNVA of 0.13 logMAR G 0.15 (SD), 0.08 G 0.15 logMAR, and 0.13 G 0.18 logMAR, respectively.8 In another study of the Tecnis ZMT in 57 eyes of 38 patients,20 postoperative UDVA, UIVA, and UNVA were 0.12 G 0.16 logMAR, 0.21 G 0.13 logMAR, and 0.10 G 0.14 logMAR, respectively. Further investigation of the rotational stability of toric IOLs in myopic eyes is necessary before general recommendations for IOL sizing can be made. Advances in anterior segment imaging (eg, ultrasound biomicroscopy and optical coherence tomography),
may provide better prediction of capsular bag dimensions in the future. In the meantime, however, careful patient screening and IOL selection with regard to AL and capsular bag size in myopic patients are important to avoid postoperative complications due to IOL rotation. As a general rule, one might opt for loop-haptic IOLs with a 13.0 mm overall diameter in this subset of patients. In conclusion, even in eyes with moderate myopia, the capsular bag diameter may be large, leading to insufficient IOL fixation and poor postoperative outcome. If care is taken in patient selection and preoperative assessment, toric IOLs provide good postoperative visual outcome in patients with abnormal optical dimensions due to myopia. REFERENCES 1. Auffarth GU, Rabsilber TM. Torische Hinterkammerlinsen nach Kataraktoperation und refraktivem Linsenaustausch [Toric IOLs after cataract surgery and refractive lens exchange]. Ophthalmologe 2007; 104:1024–1031 2. 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 3. Lam DKT, Chow VWS, Ye C, Ng PK-F, Wang Z, Jhanji V. Comparative evaluation of aspheric toric intraocular lens implantation and limbal relaxing incisions in eyes with cataracts and %3 dioptres of astigmatism. Br J Ophthalmol 2015 Jun 18. [Epub ahead of print] 4. Lee BS, Lindstrom RL, Reeves SW, Hardten DR. Modern management of astigmatism. Int Ophthalmol Clin 2013; 53:65–78 5. Denoyer A, Landman E, Trinh L, Faure J-F, Auclin F, Baudouin C. Dry eye disease after refractive surgery; comparative outcomes of small incision lenticule extraction versus LASIK. Ophthalmology 2014; 122:669–676 6. Visser N, Bauer NJC, Nuijts RMMA. Toric intraocular lenses: historical overview, patient selection, IOL calculation, surgical techniques, clinical outcomes, and complications. J Cataract Refract Surg 2013; 39:624–637 7. Khoramnia R, Fitting A, Rabsilber TM, Auffarth GU, Holzer MP. Postoperative Ergebnisse nach Implantation einer torischen, as€rischen Intraokularlinse [Postoperative results after implanpha tation of a toric, aspheric intraocular lens]. Klin Monatsbl Augenheilkd 2015; 232:867–873 8. Kretz FT, Breyer D, Klabe K, Hagen P, Kaymak H, Koss MJ, Gerl M, Mueller M, Gerl RH, Auffarth GU. Clinical outcomes after implantation of a trifocal toric intraocular lens. J Refract Surg 2015; 31:504–510. Available at: http://www.healio.com/ophthalmology/ journals/jrs/2015-8-31-8/%7Be12f84f5-cfc3-4fea-986e-b252d 0c58e1f%7D/clinical-outcomes-after-implantation-of-a-trifocaltoric-intraocular-lens.pdf. Accessed January 20, 2015 9. Chang DF. Early rotational stability of the longer Staar toric intraocular lens; fifty consecutive cases. J Cataract Refract Surg 2003; 29:935–940 10. Sanders DR, Grabow HB, Shepherd J. The toric IOL. In: Gills JP, Martin RG, Sanders DR, eds, Sutureless Cataract Surgery; an Evolution Toward Minimally Invasive Technique. Thorofare, NJ, Slack, 1992; 183–197 11. Patel CK, Ormonde S, Rosen PH, Bron AJ. Postoperative intraocular lens rotation: a randomized comparison of plate and loop
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First author: Bert C. Giers, MD Department of Ophthalmology, International Vision Correction Research Center, University of Heidelberg, Heidelberg, Germany