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Three-haptic intraocular lens for myopia: Early results
ARTICLE
Three-haptic intraocular lens for myopia: Early results Imran J. Khan, MRCOphth, Joseph Abbott, MRCOphth, Ajay J. Bhatnager, FRCOphth, Nicholas J. Price, FRCOphth
PURPOSE: To report the intraoperative experience and early postoperative results of implantation of an intraocular lens (IOL) developed specifically for myopic eyes. SETTING: Wolverhampton Eye Infirmary, Wolverhampton, United Kingdom. METHODS: This retrospective study evaluated consecutive highly myopic eyes having implantation of a Bigbag IOL from November 2003 to December 2007. Before IOL placement, a 2.8 mm clear corneal incision was created and phacoemulsification performed. The IOL was implanted using the dedicated folder and injector supplied by the manufacturer. RESULTS: The study evaluated 67 eyes (48 patients) with a mean follow-up of 8.5 months (range 0.75 to 31 months). Intraoperative complications were IOL haptic damage from the injector system (3 eyes; 4.5%) and posterior capsule tear (1 eye; 1.5%). Postoperative complications were posterior capsule opacification (29 eyes; 43%), retinal detachment (1 eye; 1.5%), and iritis (1 eye; 1.5%). The postoperative corrected distance visual acuity was 0.10 logMAR or better in 24 eyes (35.8%) and 0.18 to 0.48 logMAR in 32 eyes (47.8%). Forty-three eyes (64.2%) were within G1.00 diopter of the intended refractive outcome. CONCLUSION: Preliminary results indicate that this 3-haptic IOL is safe and appropriate for use in highly myopic patients having cataract surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2010; 36:1161–1166 Q 2010 ASCRS and ESCRS
Cataract surgery is challenging in highly myopic eyes. There is an increased risk for intraoperative complications from posterior capsule rupture1 and for subsequent retinal detachment (RD).2 The risk for RD in cataract surgery in a normal population is approximately 1% over a 10-year period.3 In patients with an axial length (AL) greater
Submitted: October 21, 2009. Final revision submitted: January 7, 2010. Accepted: January 14, 2010. From Wolverhampton Eye Infirmary, New Cross Hospital, Wolverhampton, United Kingdom. Darius Khan produced the graphics. Corresponding author: Imran J. Khan, MRCOphth, Victoria Eye Unit, Hereford County Hospital, Hereford Hospitals NHS Trust, Union Walk, Hereford, HR1 2ER, United Kingdom. E-mail: drijk@ doctors.org.uk. Q 2010 ASCRS and ESCRS Published by Elsevier Inc.
than 27.0 mm, the 10-year risk after phacoemulsification with in-the-bag intraocular lens (IOL) implantation is up to 5%.4 Furthermore, the risk increases proportional to the degree of myopia in eyes having phacoemulsification.5 The reported rate of posterior capsule opacification (PCO) after cataract surgery in myopic patients varies greatly. Some studies found no increased risk in cases of myopia6 and attribute the low PCO rates to the use of sharp-edged acrylic IOLs. Other studies report rates as high as 61%.7 Intraocular lenses of different optic material,8 haptic material,9 and optic edge profile10 are equally stable in the capsular bag. In this study of highly myopic patients, we evaluated the safety profile and intraoperative and postoperative experience with an IOL designed for myopia. Included in the analysis were refractive outcomes and the rates of RD, PCO, and neodymium:YAG (Nd:YAG) laser posterior capsulotomy. To our knowledge, other than single cases,11 0886-3350/$dsee front matter doi:10.1016/j.jcrs.2010.01.031
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there are no studies of the performance of this IOL model in the ophthalmic literature. PATIENTS AND METHODS Consecutive eyes with an AL of 26.0 mm or greater that had cataract surgery by the same surgeon (N.J.P.) between November 2003 and December 2007 were selected for study. The case notes were reviewed retrospectively. Cases were identified through surgical logs. Preoperative assessment included a detailed retinal examination with indirect ophthalmoscopy and scleral indentation to exclude preexisting RD. When the examiner (N.J.P.) deemed it appropriate, prophylactic indirect laser retinopexy was applied to reduce the risk for subsequent RD. Biometry was performed by partial coherence interferometry (PCI) (IOLMaster, Carl Zeiss Meditec AG) when possible. When the PCI results were equivocal, biometry was confirmed by A-scan (Nidek Echoscan-2000) and the IOL power was calculated using the SRK/T formula. All patients had at least 1 follow-up appointment.
Intraocular Lens All eyes had implantation of a Bigbag IOL (Carl Zeiss Meditec, previously by SD Ophthalmics) developed for use in highly myopic eyes. The single-piece hydrophilic acrylic IOL is available in powers from 10.00 to C13.00 diopters (D) in 0.50 D increments and has 3 haptics, which are posteriorly angulated by 12 degrees. Each haptic has 80 degrees of arc of contact. The overall IOL diameter is 10.5 mm and the optic diameter, 6.5 mm (Figure 1).
Surgical Technique All eyes had standard phacoemulsification under local anesthesia performed through a temporal 2.8 mm clear corneal incision. A 6.5 mm diameter continuous curvilinear capsulorhexis was created; the diameter was measured using calipers on the cornea. Visible posterior capsule lens remnants were carefully removed by vacuum. On completion of phacoemulsification, the IOL was implanted in the capsular bag using the included folder and introducer. The manufacturer also provides a double-pronged instrument to press
Figure 1. Configuration of the 3-haptic IOL.
down and fold the optic into position over the central ridge of the open cartridge. The haptics are then folded on top of each other and the wings of the cartridge closed. After the initial cases, it was found that a McPherson forceps was better for folding the optic and haptics. The IOL was then pushed into the cartridge nozzle using the rod on the opposite end of the supplied instrument. The cartridge was then locked into the injector.
Postoperative Outcome Measures Outcome measures included corrected distance visual acuity (CDVA) and refractive error. Intraoperative and postoperative complications were also recorded, with particular attention to IOL decentration and the need for additional procedures.
RESULTS Preoperative Characteristics The study included 67 eyes of 48 patients. Table 1 shows the preoperative characteristics of the patients. Thirty-two eyes (47.8%) had a preoperative comorbidity that affected the macula; the most prevalent comorbidity was age-related macular degeneration (AMD) without choroidal neovascular membrane. Intraoperative Course In-the-bag IOL fixation was achieved in 66 eyes (98.5%). Seven eyes (10.4%) had intraoperative complications (Table 2). The posterior capsule tear occurred during aspiration of soft lens matter with vitreous prolapse, necessitating vitrectomy. The IOL was placed in the sulcus. The surgeon noted IOL decentration initially but not at the final follow-up. Cases in which the IOL was delivered into the eye with a damaged and fragmented haptic occurred because of problems with the IOL delivery system. In these cases, the free-floating fragments were carefully removed. The IOL was stable and well centered; thus, no case with haptic damage required IOL exchange. The haptic damage occurred in the earlier cases (ie, before the switch to McPherson forceps for folding the optic and haptics). The IOL exchange occurred when an IOL of the correct numerical power but with a minus power instead of a plus power was implanted. The surgeon and assistant had checked the IOL but had missed the small minus sign on the packaging. The IOL was explanted during a secondary procedure performed immediately afterward. The IOL was divided with long spring scissors. The correct IOL was inserted without complication or extension of the corneal wound. Six patients had previous cataract surgery with implantation of a conventional 2-haptic IOL in 1 eye. Two of the patients reported halos around lights in
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Table 1. Preoperative patient characteristics.
Table 2. Intraoperative complications.
Characteristic
Result
Complication
Eyes/patients (n) Age (y) Mean G SD Range Sex, n (%) Female Male Laterality, n (%) Right Left Follow-up (mo) Mean G SD Range Biometry Spherical error (D) Mean G SD Range AL (mm) Mean G SD Range IOL power (D) Mean G SD Range Preop ocular morbidity, n (%) Any macular comorbidity Retinal tear/degeneration requiring preop laser retinopexy Total RDs Macula-on RD AMD with CNVM AMD without CNVM Amblyopia Visual acuity (logMAR) UDVA Mean G SD Range CDVA Mean G SD Range
67/48
Anterior capsule tear Posterior capsule tear Haptic damaged by injector Eccentric IOL position Vitrectomy IOL exchange (incorrect IOL inserted)
66.2 G 12.1 41 to 90 30 (63) 18 (27)
Number (%) 2 (3.0) 1 (1.5) 3 (4.5) 1 (1.5) 1 (1.5) 1 (1.5)
IOL Z intraocular lens
38 (57) 29 (43) 8.5 G 7.7 0.75 to 31.00
12.86 G 6.00 29.13 to 3.50 28.59 G 2.10 25.89 to 34.03 C3.70 G 4.80 6.00 to C13.50 32 (48) 7(10) 6 (9) 2 (3) 1 (1) 8 (12) 4 (6)
2.00 G 0.51 0.48 to 3.00 0.50 G 0.69 0.18 to 3.00
AMD Z age-related macular degeneration; CDVA Z corrected distance visual acuity; CNVM Z choroidal neovascular membrane; RD Z retinal detachment; UDVA Z uncorrected distance visual acuity
the eye with the conventional IOL but not in the eye with the 3-haptic IOL. Postoperative Course Table 3 shows the preoperative and postoperative uncorrected distance visual acuity (UDVA) and CDVA. The 2 patients with the worst CDVA (R1.00 logMAR) had preoperative maculopathy; neither had deterioration in visual acuity postoperatively. Comparison of the cumulative preoperative and postoperative visual acuity showed a significant
improvement in UDVA postoperatively (Figure 2). The CDVA also improved, but to a lesser extent (Figure 3). During follow-up, 29 eyes (43.3%) developed PCO, 1 eye (1.5%) had an RD, and 1 eye developed iritis (1.5%). Of the eyes with PCO, 27 (93.1%) had an Nd:YAG capsulotomy. All Nd:YAG capsulotomies were uneventful. Twenty-nine eyes (44%) were within G0.50 D of the targeted spherical equivalent (SE) refraction, and 43 eyes (65%) were within G1.00 D (Figure 4).
DISCUSSION The diameter of the capsular bag after cataract surgery is positively correlated with the AL of the eye.12,13 Cadaver studies show that IOLs with a 12.0 mm haptic diameter distort the capsular bag less than larger IOLs and are more stable than smaller IOLs.13 Results in previous studies suggest that a 2-haptic IOL with a haptic diameter smaller than 12.5 mm is not stable when implanted in a large capsular bag.14 In contrast, our results indicate that the 3-haptic IOL we evaluated (haptic diameter 10.35 mm) is stable in a large capsular bag; to date, there has been only 1 case of IOL decentration in our highly myopic population. The 3-haptic IOL has a larger diameter optic (6.5 mm), which is better suited to myopic eyes with a large pupil under scotopic conditions.15 Choroidal detachments and postoperative intraocular pressure (IOP) rise have been reported after removal of the crystalline lens in eyes with extreme myopia.16 No eye in our study developed either complication. One study17 reports a CDVA of 20/40 or better in 88.5% of eyes 1 year after refractive lens exchange (RLE) with posterior chamber IOL implantation. For comparison, we applied the same selection criteria as that study to our group of patients (preoperative 12.00 D SE or greater; preoperative CDVA 20/100 or better). This yielded a CDVA of 20/40 or better in
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Table 3. Visual acuity outcomes. Preoperative LogMAR Value %0.10 0.18-0.48 0.50-0.9 R1.00
Postoperative
UDVA
CDVA
UDVA
CDVA
0 1 (1.5) 0 52 (77.6)
0 31 (46.3) 15 (22.4) 20 (29.9)
16 (23.9) 32 (47.8) 7 (10.4) 5 (7.5)
24 (35.8) 32 (47.8) 8 (11.9) 2 (3.0)
CDVA Z corrected distance visual acuity; UDVA Z uncorrected distance visual acuity
94% of our patients, who were significantly older (mean age 66.2 years) than the patients in the previous study (mean age 36.2 years). Even without exclusions, the CDVA in our study was 20/40 or better in 80.1% of eyes, which compares favorably to contemporary reports of RLE in eyes with myopia.18 The risk for capsular block syndrome has been reported to be greater after implantation of IOLs with 3 or more haptics.19 However, no eye in our study had postoperative anterior displacement of the IOL or anterior chamber shallowing. We found no evidence that the 3-haptic design of the IOL predisposes to capsular block syndrome; the 12-degree posterior haptic angulation is the likely reason for this finding. The rate of PCO in our study was 43.3%. Most previous studies report PCO rates of 20% to 50%,2,20–25 although the rate varies from 3.5% (at 24 months)6 to 61.0% (mean follow-up 64 months)7 according to the surgical technique, length of follow-up, and inclusion criteria. It will be of interest to see whether Nd:YAG capsulotomy is associated with an increased RD rate in our patients; 1 study26 in which 85% of patients
Figure 3. Preoperative and postoperative cumulative CDVA.
Figure 2. Preoperative and postoperative cumulative UDVA.
were left aphakic after lens extraction found that Nd:YAG laser capsulotomy increased the rate of subsequent RD. It has been suggested that the IOL has a role in supporting the vitreous; IOL implantation has been shown to largely negate the risk for RD.4 There were no cases of capsule phimosis in our study, probably because the long haptic circumference acts as a capsular tension ring, which prevents a significant degree of capsule contraction. We performed an analysis of refractive outcomes that differed most from the expected value. In those 14 eyes, the magnitude by which the actual refractive outcome differed from the predicted (or target) value had a weak positive relationship with AL and a weak negative correlation with the signal-to-noise ratio with the PCI device we used in our study. This suggests that the SRK/T formula may be consistently inaccurate in eyes with a longer AL. It is possible that inaccurate prediction of postoperative refractive
Figure 4. Distribution of expected refractive outcome versus target refractive outcome (SE Z spherical equivalent).
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outcomes was the result of a low signal-to-noise ratio on biometry. One eye in our study had an RD after uneventful surgery. Preoperatively, there were no indications for prophylactic retinopexy on indirect ophthalmoscopy with scleral indentation. None of the 7 cases that had prophylactic retinopexy have developed an RD or a complication attributable to the retinal laser procedure to date. Recent studies report RD rates from 0%27 (in a considerably younger patient group) to 8.1%17 7 years after RLE with IOL implantation. It remains to be seen whether the RD rate in our cohort will be comparable over time. Conclusions from this study should be taken in the context of the relatively short follow-up period. This was a preliminary study of intraoperative and early postoperative results rather than a definitive retrospective analysis. Eventual rates of RD and PCO are likely to be higher than those reported at the time of writing. We believe that this is the first published study reporting outcomes and experiences with the 3-haptic IOL designed for myopic eyes. Our CDVA data compare favorably to results in analogous studies. During the early postoperative course, the incidence of RD was consistent with that in the literature. The injector system damaged a haptic in a few eyes, although the IOL remained stable in all cases. Haptic damage can be avoided by carefully inspecting the cartridge. The haptics captured in the cartridge should be inspected by looking through the cartridge against a bright backlight after the cartridge is closed. In conclusion, our preliminary results indicate that the 3-haptic IOL is safe and appropriate for use in highly myopic eyes having cataract surgery.
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detachment after cataract surgery; a population-based casecontrol study. Ophthalmology 1996; 103:1537–1545 Hayashi K, Yoshida M, Hayashi H. Posterior capsule opacification in myopic eyes. J Cataract Refract Surg 2006; 32:634–638 Horgan N, Condon PI, Beatty S. Refractive lens exchange in high myopia: long term follow up. Br J Ophthalmol 2005; 89:670–672. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC177 2665/pdf/bjo08900670.pdf. Accessed March 18, 2010 Hayashi K, Harada M, Hayashi H, Nakao F, Hayashi F. Decentration and tilt of polymethyl methacrylate, silicon, and acrylic soft intraocular lenses. Ophthalmology 1997; 104:793–798 Mutlu FM, Erdurman C, Sobaci G, Bayraktar MZ. Comparison of tilt and decentration of 1-piece and 3-piece hydrophobic acrylic intraocular lenses. J Cataract Refract Surg 2005; 31:343–347 Baumeister M, Neidhardt B, Strobel J, Kohnen T. Tilt and decentration of three-piece foldable high-refractive silicone and hydrophobic acrylic intraocular lenses with 6-mm optics in an intraindividual comparison. Am J Ophthalmol 2005; 140: 1051–1058 Bhatnagar A, Somanathan S, Scott RAH. Bilateral big-bag intraocular lens implant for highly myopic eyes [letter]. Eye 2006; 20:1463–1464 Vass C, Menapace R, Schemetterer 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 Tan˜a´ P, Belmonte J. Experimental study of different intraocular lens designs implanted in the bag after capsulorhexis. J Cataract Refract Surg 1996; 22:1211–1221 Lim SJ, Kang SJ, Kim HB, Apple DJ. Ideal size of an intraocular lens for capsular bag fixation. J Cataract Refract Surg 1998; 24:397–402 Chaidaroon W, Juwattanasomran W. Colvard pupillometer measurement of scotopic pupil diameter in emmetropes and myopes. Jpn J Ophthalmol 2002; 46:640–644 Jime´nez-Alfaro I, Migue´lez S, Bueno JL, Puy P. Clear lens extraction and implantation of negative-power posterior chamber intraocular lenses to correct extreme myopia. J Cataract Refract Surg 1998; 24:1310–1316 Colin J, Robinet A. Clear lensectomy and implantation of low-power posterior chamber intraocular lens for the correction of high myopia. Ophthalmology 1994; 101:107–112 Ferna´ndez-Vega L, Alfonso JF, Villacampa T. Clear lens extraction for the correction of high myopia. Ophthalmology 2003; 110:2349–2354 Kim HK, Shin JP. Capsular block syndrome after cataract surgery: clinical analysis and classification. J Cataract Refract Surg 2008; 34:357–363 Lyle WA, Jin GJ. Phacoemulsification with intraocular lens implantation in high myopia. J Cataract Refract Surg 1996; 22:238–242 Ceschi GP, Artaria LG. Clear Lens Extraction (CLE) zur Korrektur der hochgradigen Myopie [Clear lens extraction (CLE) for correction of high grade myopia]. Klin Monatsbl Augenheilkd 1998; 212:280–282 Alldredge CD, Elkins B, Alldredge OC Jr. Retinal detachment following phacoemulsification in highly myopic cataract patients. J Cataract Refract Surg 1998; 24:777–780 Pucci V, Morselli S, Romenelli F, Pignatto S, Scandellari F, Bellucci R. Clear lens phacoemulsification for correction of high myopia. J Cataract Refract Surg 2001; 27:896–900 Ravalico G, Michieli C, Vattovani O, Tognetto D. Retinal detachment after cataract extraction and refractive lens
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exchange in highly myopic patients. J Cataract Refract Surg 2003; 29:39–44 25. Alio JL, Ruiz-Moreno JM, Shabayek MH, Lugo FL, El Rahman AMA. The risk of retinal detachment in high myopia after small incision coaxial phacoemulsification. Am J Ophthalmol 2007; 144:93–98 26. Barraquer C, Cavelier C, Mejı´a LF. Incidence of retinal detachment following clear-lens extraction in myopic patients; retrospective analysis. Arch Ophthalmol 1994; 112: 336–339 27. Gu¨ell JL, Rodriguez-Arenas AF, Gris O, Malecaze F, Velasco F. Phacoemulsification of the crystalline lens and implantation of
an intraocular lens for the correction of moderate and high myopia: four-year follow-up. J Cataract Refract Surg 2003; 29:34–38
J CATARACT REFRACT SURG - VOL 36, JULY 2010
First author: Imran J. Khan, MRCOphth Wolverhampton Eye Infirmary, New Cross Hospital, Wolverhampton, United Kingdom
Three-haptic intraocular lens for myopia: Early results Imran J. Khan, MRCOphth, Joseph Abbott, MRCOphth, Ajay J. Bhatnager, FRCOphth, Nicholas J. Price, FRCOphth
PURPOSE: To report the intraoperative experience and early postoperative results of implantation of an intraocular lens (IOL) developed specifically for myopic eyes. SETTING: Wolverhampton Eye Infirmary, Wolverhampton, United Kingdom. METHODS: This retrospective study evaluated consecutive highly myopic eyes having implantation of a Bigbag IOL from November 2003 to December 2007. Before IOL placement, a 2.8 mm clear corneal incision was created and phacoemulsification performed. The IOL was implanted using the dedicated folder and injector supplied by the manufacturer. RESULTS: The study evaluated 67 eyes (48 patients) with a mean follow-up of 8.5 months (range 0.75 to 31 months). Intraoperative complications were IOL haptic damage from the injector system (3 eyes; 4.5%) and posterior capsule tear (1 eye; 1.5%). Postoperative complications were posterior capsule opacification (29 eyes; 43%), retinal detachment (1 eye; 1.5%), and iritis (1 eye; 1.5%). The postoperative corrected distance visual acuity was 0.10 logMAR or better in 24 eyes (35.8%) and 0.18 to 0.48 logMAR in 32 eyes (47.8%). Forty-three eyes (64.2%) were within G1.00 diopter of the intended refractive outcome. CONCLUSION: Preliminary results indicate that this 3-haptic IOL is safe and appropriate for use in highly myopic patients having cataract surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2010; 36:1161–1166 Q 2010 ASCRS and ESCRS
Cataract surgery is challenging in highly myopic eyes. There is an increased risk for intraoperative complications from posterior capsule rupture1 and for subsequent retinal detachment (RD).2 The risk for RD in cataract surgery in a normal population is approximately 1% over a 10-year period.3 In patients with an axial length (AL) greater
Submitted: October 21, 2009. Final revision submitted: January 7, 2010. Accepted: January 14, 2010. From Wolverhampton Eye Infirmary, New Cross Hospital, Wolverhampton, United Kingdom. Darius Khan produced the graphics. Corresponding author: Imran J. Khan, MRCOphth, Victoria Eye Unit, Hereford County Hospital, Hereford Hospitals NHS Trust, Union Walk, Hereford, HR1 2ER, United Kingdom. E-mail: drijk@ doctors.org.uk. Q 2010 ASCRS and ESCRS Published by Elsevier Inc.
than 27.0 mm, the 10-year risk after phacoemulsification with in-the-bag intraocular lens (IOL) implantation is up to 5%.4 Furthermore, the risk increases proportional to the degree of myopia in eyes having phacoemulsification.5 The reported rate of posterior capsule opacification (PCO) after cataract surgery in myopic patients varies greatly. Some studies found no increased risk in cases of myopia6 and attribute the low PCO rates to the use of sharp-edged acrylic IOLs. Other studies report rates as high as 61%.7 Intraocular lenses of different optic material,8 haptic material,9 and optic edge profile10 are equally stable in the capsular bag. In this study of highly myopic patients, we evaluated the safety profile and intraoperative and postoperative experience with an IOL designed for myopia. Included in the analysis were refractive outcomes and the rates of RD, PCO, and neodymium:YAG (Nd:YAG) laser posterior capsulotomy. To our knowledge, other than single cases,11 0886-3350/$dsee front matter doi:10.1016/j.jcrs.2010.01.031
1161
1162
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there are no studies of the performance of this IOL model in the ophthalmic literature. PATIENTS AND METHODS Consecutive eyes with an AL of 26.0 mm or greater that had cataract surgery by the same surgeon (N.J.P.) between November 2003 and December 2007 were selected for study. The case notes were reviewed retrospectively. Cases were identified through surgical logs. Preoperative assessment included a detailed retinal examination with indirect ophthalmoscopy and scleral indentation to exclude preexisting RD. When the examiner (N.J.P.) deemed it appropriate, prophylactic indirect laser retinopexy was applied to reduce the risk for subsequent RD. Biometry was performed by partial coherence interferometry (PCI) (IOLMaster, Carl Zeiss Meditec AG) when possible. When the PCI results were equivocal, biometry was confirmed by A-scan (Nidek Echoscan-2000) and the IOL power was calculated using the SRK/T formula. All patients had at least 1 follow-up appointment.
Intraocular Lens All eyes had implantation of a Bigbag IOL (Carl Zeiss Meditec, previously by SD Ophthalmics) developed for use in highly myopic eyes. The single-piece hydrophilic acrylic IOL is available in powers from 10.00 to C13.00 diopters (D) in 0.50 D increments and has 3 haptics, which are posteriorly angulated by 12 degrees. Each haptic has 80 degrees of arc of contact. The overall IOL diameter is 10.5 mm and the optic diameter, 6.5 mm (Figure 1).
Surgical Technique All eyes had standard phacoemulsification under local anesthesia performed through a temporal 2.8 mm clear corneal incision. A 6.5 mm diameter continuous curvilinear capsulorhexis was created; the diameter was measured using calipers on the cornea. Visible posterior capsule lens remnants were carefully removed by vacuum. On completion of phacoemulsification, the IOL was implanted in the capsular bag using the included folder and introducer. The manufacturer also provides a double-pronged instrument to press
Figure 1. Configuration of the 3-haptic IOL.
down and fold the optic into position over the central ridge of the open cartridge. The haptics are then folded on top of each other and the wings of the cartridge closed. After the initial cases, it was found that a McPherson forceps was better for folding the optic and haptics. The IOL was then pushed into the cartridge nozzle using the rod on the opposite end of the supplied instrument. The cartridge was then locked into the injector.
Postoperative Outcome Measures Outcome measures included corrected distance visual acuity (CDVA) and refractive error. Intraoperative and postoperative complications were also recorded, with particular attention to IOL decentration and the need for additional procedures.
RESULTS Preoperative Characteristics The study included 67 eyes of 48 patients. Table 1 shows the preoperative characteristics of the patients. Thirty-two eyes (47.8%) had a preoperative comorbidity that affected the macula; the most prevalent comorbidity was age-related macular degeneration (AMD) without choroidal neovascular membrane. Intraoperative Course In-the-bag IOL fixation was achieved in 66 eyes (98.5%). Seven eyes (10.4%) had intraoperative complications (Table 2). The posterior capsule tear occurred during aspiration of soft lens matter with vitreous prolapse, necessitating vitrectomy. The IOL was placed in the sulcus. The surgeon noted IOL decentration initially but not at the final follow-up. Cases in which the IOL was delivered into the eye with a damaged and fragmented haptic occurred because of problems with the IOL delivery system. In these cases, the free-floating fragments were carefully removed. The IOL was stable and well centered; thus, no case with haptic damage required IOL exchange. The haptic damage occurred in the earlier cases (ie, before the switch to McPherson forceps for folding the optic and haptics). The IOL exchange occurred when an IOL of the correct numerical power but with a minus power instead of a plus power was implanted. The surgeon and assistant had checked the IOL but had missed the small minus sign on the packaging. The IOL was explanted during a secondary procedure performed immediately afterward. The IOL was divided with long spring scissors. The correct IOL was inserted without complication or extension of the corneal wound. Six patients had previous cataract surgery with implantation of a conventional 2-haptic IOL in 1 eye. Two of the patients reported halos around lights in
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Table 1. Preoperative patient characteristics.
Table 2. Intraoperative complications.
Characteristic
Result
Complication
Eyes/patients (n) Age (y) Mean G SD Range Sex, n (%) Female Male Laterality, n (%) Right Left Follow-up (mo) Mean G SD Range Biometry Spherical error (D) Mean G SD Range AL (mm) Mean G SD Range IOL power (D) Mean G SD Range Preop ocular morbidity, n (%) Any macular comorbidity Retinal tear/degeneration requiring preop laser retinopexy Total RDs Macula-on RD AMD with CNVM AMD without CNVM Amblyopia Visual acuity (logMAR) UDVA Mean G SD Range CDVA Mean G SD Range
67/48
Anterior capsule tear Posterior capsule tear Haptic damaged by injector Eccentric IOL position Vitrectomy IOL exchange (incorrect IOL inserted)
66.2 G 12.1 41 to 90 30 (63) 18 (27)
Number (%) 2 (3.0) 1 (1.5) 3 (4.5) 1 (1.5) 1 (1.5) 1 (1.5)
IOL Z intraocular lens
38 (57) 29 (43) 8.5 G 7.7 0.75 to 31.00
12.86 G 6.00 29.13 to 3.50 28.59 G 2.10 25.89 to 34.03 C3.70 G 4.80 6.00 to C13.50 32 (48) 7(10) 6 (9) 2 (3) 1 (1) 8 (12) 4 (6)
2.00 G 0.51 0.48 to 3.00 0.50 G 0.69 0.18 to 3.00
AMD Z age-related macular degeneration; CDVA Z corrected distance visual acuity; CNVM Z choroidal neovascular membrane; RD Z retinal detachment; UDVA Z uncorrected distance visual acuity
the eye with the conventional IOL but not in the eye with the 3-haptic IOL. Postoperative Course Table 3 shows the preoperative and postoperative uncorrected distance visual acuity (UDVA) and CDVA. The 2 patients with the worst CDVA (R1.00 logMAR) had preoperative maculopathy; neither had deterioration in visual acuity postoperatively. Comparison of the cumulative preoperative and postoperative visual acuity showed a significant
improvement in UDVA postoperatively (Figure 2). The CDVA also improved, but to a lesser extent (Figure 3). During follow-up, 29 eyes (43.3%) developed PCO, 1 eye (1.5%) had an RD, and 1 eye developed iritis (1.5%). Of the eyes with PCO, 27 (93.1%) had an Nd:YAG capsulotomy. All Nd:YAG capsulotomies were uneventful. Twenty-nine eyes (44%) were within G0.50 D of the targeted spherical equivalent (SE) refraction, and 43 eyes (65%) were within G1.00 D (Figure 4).
DISCUSSION The diameter of the capsular bag after cataract surgery is positively correlated with the AL of the eye.12,13 Cadaver studies show that IOLs with a 12.0 mm haptic diameter distort the capsular bag less than larger IOLs and are more stable than smaller IOLs.13 Results in previous studies suggest that a 2-haptic IOL with a haptic diameter smaller than 12.5 mm is not stable when implanted in a large capsular bag.14 In contrast, our results indicate that the 3-haptic IOL we evaluated (haptic diameter 10.35 mm) is stable in a large capsular bag; to date, there has been only 1 case of IOL decentration in our highly myopic population. The 3-haptic IOL has a larger diameter optic (6.5 mm), which is better suited to myopic eyes with a large pupil under scotopic conditions.15 Choroidal detachments and postoperative intraocular pressure (IOP) rise have been reported after removal of the crystalline lens in eyes with extreme myopia.16 No eye in our study developed either complication. One study17 reports a CDVA of 20/40 or better in 88.5% of eyes 1 year after refractive lens exchange (RLE) with posterior chamber IOL implantation. For comparison, we applied the same selection criteria as that study to our group of patients (preoperative 12.00 D SE or greater; preoperative CDVA 20/100 or better). This yielded a CDVA of 20/40 or better in
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Table 3. Visual acuity outcomes. Preoperative LogMAR Value %0.10 0.18-0.48 0.50-0.9 R1.00
Postoperative
UDVA
CDVA
UDVA
CDVA
0 1 (1.5) 0 52 (77.6)
0 31 (46.3) 15 (22.4) 20 (29.9)
16 (23.9) 32 (47.8) 7 (10.4) 5 (7.5)
24 (35.8) 32 (47.8) 8 (11.9) 2 (3.0)
CDVA Z corrected distance visual acuity; UDVA Z uncorrected distance visual acuity
94% of our patients, who were significantly older (mean age 66.2 years) than the patients in the previous study (mean age 36.2 years). Even without exclusions, the CDVA in our study was 20/40 or better in 80.1% of eyes, which compares favorably to contemporary reports of RLE in eyes with myopia.18 The risk for capsular block syndrome has been reported to be greater after implantation of IOLs with 3 or more haptics.19 However, no eye in our study had postoperative anterior displacement of the IOL or anterior chamber shallowing. We found no evidence that the 3-haptic design of the IOL predisposes to capsular block syndrome; the 12-degree posterior haptic angulation is the likely reason for this finding. The rate of PCO in our study was 43.3%. Most previous studies report PCO rates of 20% to 50%,2,20–25 although the rate varies from 3.5% (at 24 months)6 to 61.0% (mean follow-up 64 months)7 according to the surgical technique, length of follow-up, and inclusion criteria. It will be of interest to see whether Nd:YAG capsulotomy is associated with an increased RD rate in our patients; 1 study26 in which 85% of patients
Figure 3. Preoperative and postoperative cumulative CDVA.
Figure 2. Preoperative and postoperative cumulative UDVA.
were left aphakic after lens extraction found that Nd:YAG laser capsulotomy increased the rate of subsequent RD. It has been suggested that the IOL has a role in supporting the vitreous; IOL implantation has been shown to largely negate the risk for RD.4 There were no cases of capsule phimosis in our study, probably because the long haptic circumference acts as a capsular tension ring, which prevents a significant degree of capsule contraction. We performed an analysis of refractive outcomes that differed most from the expected value. In those 14 eyes, the magnitude by which the actual refractive outcome differed from the predicted (or target) value had a weak positive relationship with AL and a weak negative correlation with the signal-to-noise ratio with the PCI device we used in our study. This suggests that the SRK/T formula may be consistently inaccurate in eyes with a longer AL. It is possible that inaccurate prediction of postoperative refractive
Figure 4. Distribution of expected refractive outcome versus target refractive outcome (SE Z spherical equivalent).
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outcomes was the result of a low signal-to-noise ratio on biometry. One eye in our study had an RD after uneventful surgery. Preoperatively, there were no indications for prophylactic retinopexy on indirect ophthalmoscopy with scleral indentation. None of the 7 cases that had prophylactic retinopexy have developed an RD or a complication attributable to the retinal laser procedure to date. Recent studies report RD rates from 0%27 (in a considerably younger patient group) to 8.1%17 7 years after RLE with IOL implantation. It remains to be seen whether the RD rate in our cohort will be comparable over time. Conclusions from this study should be taken in the context of the relatively short follow-up period. This was a preliminary study of intraoperative and early postoperative results rather than a definitive retrospective analysis. Eventual rates of RD and PCO are likely to be higher than those reported at the time of writing. We believe that this is the first published study reporting outcomes and experiences with the 3-haptic IOL designed for myopic eyes. Our CDVA data compare favorably to results in analogous studies. During the early postoperative course, the incidence of RD was consistent with that in the literature. The injector system damaged a haptic in a few eyes, although the IOL remained stable in all cases. Haptic damage can be avoided by carefully inspecting the cartridge. The haptics captured in the cartridge should be inspected by looking through the cartridge against a bright backlight after the cartridge is closed. In conclusion, our preliminary results indicate that the 3-haptic IOL is safe and appropriate for use in highly myopic eyes having cataract surgery.
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First author: Imran J. Khan, MRCOphth Wolverhampton Eye Infirmary, New Cross Hospital, Wolverhampton, United Kingdom