IC-15: Strategies and techniques for IOL exchange
M.J. Tassignon
Cataract surgery consisting of an anterior continuous curvilinear capsulorhexis, phacoemulsification, and
lens-in-the-bag intraocular lens (IOL) implantation has become the standard surgical procedure to restore
the transparency of the natural crystalline lens. The visual outcomes after cataract surgery became very
predictable with the advent of phacoemulsification, foldable IOLs, small-incision surgery, and better IOL
calculation formulas.1
Surgical improvements have decreased the incidence of IOL exchange over the past decade. In a
retrospective study performed between 1998 and 2004, Jin et al. 2 found that the most frequent indications
for IOL exchange were incorrect IOL power calculation (41.2%) followed by IOL dislocation or decentration
(37.3%) and glare (7.8%). In a study performed between 1986 and1990 in the same clinical setting,3
corneal decompensation (38.6%), abnormal IOL position (22.8%), incorrect IOL power (13.9%), and
cystoid macular edema (13.9%) were the leading causes for IOL exchange.
Mamalis et al.4 reported in a survey update in 2003 that the most frequent cause of posterior chamber IOL
exchange was decentration and/or dislocation followed by IOL miscalculation. Depending on the IOL
design and the biomaterial used, indications for explantation vary.
Surgical removal of an IOL is a challenging procedure because of the strong adherence between the IOL
and lens capsule. Several methods and instruments to reduce the risk for zonular dehiscence or rupture of
the lens capsule during surgery have been proposed. These include circumferentially enlarging the
preexisting capsulorhexis, cutting the anterior capsule rim, cutting the IOL haptics, transecting the IOL,
creating a 2-sided port incision to allow bimanual manipulation, using the Mackool foldable lens removal
system, and performing neodymium:YAG (Nd:YAG) laser disruption of the IOL optic or haptic.5–10
The purpose of this study was to determine the indications for IOL exchange over a 5-year period and to
evaluate the surgical technique, postoperative complications, and surgical outcomes after 1 year.
PATIENTS AND METHODS
This prospective study comprised patients who had an IOL exchange between October 2002 and
December 2007. The patients were referred or were previously operated on at the Department of
Ophthalmology, Antwerp University Hospital. All IOL exchanges were performed by the same surgeon
(M.J.T.). The age, sex, and systemic and ophthalmic histories of each patient were recorded. The IOL
position was described after pupil dilation. Indications for IOL exchange, time interval between the 2
surgeries, perioperative and postoperative complications, postoperative follow-up, best corrected visual
acuity (BCVA), perioperative anterior vitrectomy, and type of secondary IOL were recorded.
All patients had a full ophthalmologic evaluation including subjective complaints, intraocular pressure
(IOP), and status of the posterior segment. Special attention was paid to the preoperative status of the
posterior capsule (eg, Nd:YAG capsulotomy, posterior capsule rupture, posterior capsule opacification,
capsule contraction, stretching of zonular fibers).
In cases of subjective complaints of bad quality of vision, a glare sensitivity test (C-Quant straylight meter,
Oculus) and aberrometry (iTraceTM Visual Function Analyzer, Tracey Technologies) were performed. In
the presence of severe glare or significant coma, astigmatism, or hyperopic defocus, the indication for IOL
exchange was classified as decentration.
The new IOL power was calculated based on IOLMaster optical biometer (V.2.02, Carl Zeiss Meditec)
measurements using the SRK/T formula. Ultrasound biometry was performed in cases of unsuccessful
measurements with the optical biometer, which was most often the case in eyes with secondary IOL
opacification. The biometric measurements were recorded in all cases, independent of whether the power
of the primary implanted IOL was known. Endothelial cell density, measured with a noncontact specular
microscopy (SP1000 Specular Microscope, Topcon), was recorded before IOL exchange in a subgroup of
patients.
The IOL exchange procedure was performed using topical anesthesia (benoxinate hydrochloride 0.4%
eyedrops and lidocaine hydrochloride 0.2%), retrobulbar anesthesia (3 to 5 mL lidocaine hydrochloride
1%), or and general anesthesia. After a diluted solution of adrenalin in balanced salt solution 1/1000 was
injected, the anterior chamber was filled with a long-molecular-chain ophthalmic viscosurgical device
(OVD) (sodium hyaluronate 1.4% [Healon GV]). No adrenalin solution was used in the presence of an
anterior chamber IOL. In these cases, the incision was corneoscleral, 6.0 mm in length, and superiorly
located. Fibrotic tissue at the level of the anterior capsulorhexis edge was peeled off where possible to
restore the capsular integrity.11,12
Viscodissection of the IOL was the preferred technique for in-the-bag IOLs. A 30-gauge needle was
placed on the OVD syringe to dissect the anterior capsule rim from the IOL optic. Viscodissection was
performed until the IOL optic and haptics were completely separated from the posterior capsule. After the
IOL was mobilized in the capsular bag, the IOL was carefully dialed out of the bag and removed whole or
after it was cut into 2 or more pieces. Anterior vitrectomy was performed in all cases of vitreous prolapse,
independent of the amount of prolapse. Triamcinolone was used in selected cases of severe vitreous
prolapse into the anterior chamber.
The secondary IOL was positioned in the sulcus or in the capsular bag using the bag-in-the-lens
technique13 depending on the integrity of the capsular bag. When capsular support was inadequate, an
iris-claw IOL was fixated in front of or behind the iris14 and a peripheral iridectomy was performed. The
corneal incision was closed with 1, 2, or 3 nylon 10-0 sutures based on incision size and following the
criteria for watertightness.
Postoperative treatment consisted of a combination of topical tobramycin–dexamethasone and either
pranoprofen or ketorolac tromethamine. Both medications were given 4 times a day for 1 week and then
tapered over the following 4 weeks depending on the inflammatory status of the eye.
Postoperative follow-up was planned at 1 day, 1 and 5 weeks, 6 months, and 1 year. At each examination,
the BCVA, IOP, and objective refraction were measured and a slitlamp evaluation was performed. Followup data were checked postoperatively at the Department of Ophthalmology, or the information was
obtained from the patient’s referring ophthalmologist.
Descriptive statistics (mean, minimum, maximum, SD) were calculated for age, follow-up, and time
between the first and second operation. The correlation between Nd:YAG laser capsulotomy and
perioperative vitreous loss necessitating anterior vitrectomy was analyzed using the Fisher exact test. The
preoperative and postoperative BCVAs were calculated and compared by the paired-samples Student t
test. The influence of IOL position on the refractive outcome was analyzed using a 1-way analysis of
variance (ANOVA). Statistical analysis was performed using SPSS for Windows (version 16.0, SPSS,
Inc.). A P value less than 0.05 was considered statistically significant.
RESULTS
Table 1 shows the characteristics of the 113 patients (128 eyes) enrolled in the study. Of the patients,
81% were referred and 19% were previously operated on at the Department of Ophthalmology. Precise
information about the primary IOL type was missing for 29 eyes of patients who were referred by an
ophthalmologist who was not the primary surgeon. Follow-up data were available for 110 eyes. The date
of the primary cataract surgery was known in 124 eyes. The number of IOL exchange procedures
recorded per year was 11 in 2003, 17 in 2004, 26 in 2005, 41 in 2006, and 33 in 2007. The exchange
procedure was performed using topical anesthesia in 83 eyes (65%), retrobulbar anesthesia in 10 eyes
(8%), and general anesthesia in 35 eyes (27%).
Table 2 shows the ophthalmic (38%) and general (84%) comorbidities of the patients. All patients with
chronic open-angle glaucoma were treated preoperatively with topical medication and had controlled IOP
before surgery.
Figure 1 shows the indications for IOL explantation. Figure 2 shows representative photographs of the 4
most frequent indications for IOL exchange. The eyes with IOL decentration had associated aberrations.
The IOL exchanges performed because of corneal decompensation were of anterior chamber–fixated
IOLs. The IOL damage included severe pitting, and the cases of uveitis were IOL related. In 18 of the 24
eyes operated on because of decentration, a pseudoaccommodating IOL was implanted as follows:
Acri.Twin (Acri.Tec) in 5 eyes, Crystalens (Bausch & Lomb) in 3 eyes, AcrySof ReSTOR (Alcon
Laboratories) in 5 eyes, Array SA40N (Abbott Medical Optics, formerly Advanced Medical Optics) in 1 eye,
and unknown multifocal in 4 eyes.
The position of the IOL before exchange was in the anterior chamber in 10% of eyes (angle supported
7%, iris fixated 3%), in the capsular bag in 81%, in the ciliary sulcus in 7%, in the posterior chamber
following the bag-in-the-lens implantation technique in 1%, and suspended on the back of the iris in 1%
(Figure 3). After lens exchange, an iris-fixated IOL in the anterior chamber was implanted in 16% of eyes,
an iris-fixated IOL in the posterior chamber in 23%, an IOL in the ciliary sulcus in 15%, a posterior
chamber in-the-bag IOL in 28%, and a posterior chamber bag-in- the-lens IOL in 17%. In 1 case (1%), no
IOL was implanted because of a bad visual prognosis in a compromised eye (Figure 4).
Endothelial cell density was measured before IOL exchange in 65 patients. In 11 patients, endothelial cell
density was known before the first surgery; the mean was 2173 ± 578 cells/mm2 (range 700 to 2700
cells/mm2). The patient with the lowest cell count had herpetic keratitis. The mean endothelial cell density
in all 65 eyes measured was 1910 ± 579 cells/ mm2 (range 400 to 3200 cells/mm2). Five patients had
fewer than 1000 cells/mm 2.
Of all 113 patients, 2 required Descemet stripping automated endothelial keratoplasty after IOL exchange.
Figure 5 shows the perioperative and postoperative complications. The most frequent complication (18%)
was perioperative vitreous loss.
Preoperative Nd:YAG laser capsulotomy was strongly correlated with vitreous loss during surgery
(P = 0.001). Anterior vitrectomy was required in 18 (49%) of 37 eyes with an open capsule (ie, had
preoperative Nd:YAG capsulotomy) and 9 (10%) of 91 eyes with an intact capsule (ie, no preoperative
Nd:YAG capsulotomy). Eight of the 9 eyes without a preoperative Nd:YAG capsulotomy had capsule
rupture during the exchange procedure, and 1 had zonulysis.
In patients without vision-impairing ophthalmic comorbidity (n = 72), the mean preoperative BCVA was
0.60 ± 0.35 and the mean postoperative BCVA, 0.83 ± 0.21. There was a statistically significant increase
in visual acuity after IOL exchange (t(71) = –6.54, P < 0.001).
Figure 6 shows the targeted refraction before IOL exchange and the achieved refraction 5 weeks after
surgery in 87 eyes as a function IOL location. The mean difference between the targeted and achieved
refraction (spherical equivalent) was 1.09 ± 0.50 D (range 0.40 to 2.25 D) with anterior chamber irisfixated
IOLs, 1.55 ± 1.92 D (range 0.00 to 7.00 D) with posterior chamber iris-fixated IOLs, 0.70 ± 0.67 D (range
0.15 to 2.33 D) with sulcus-fixated IOLs, 0.62 ± 0.64 D (range 0.00 to 2.00 D) with IOLs implanted in the
capsular bag, and 0.51 ± 0.45 D (range 0.00 to 1.79 D) with IOLs implanted using the bag-in-the-lens
technique. There was a statistically significant difference between the posteriorly iris-fixated IOLs and the
bag-in-the-lens IOLs (F(4.82) = 3.23; P < 0.05, ANOVA). No other comparison was statistically significant.
DISCUSSION
According to reports in the literature, the incidence of IOL exchange seems to have decreased. However,
we have seen a steady increase in this procedure over the past 5 years.
Visual acuity can be severely impaired due to opacification of the IOL. In our study, visual acuity in eyes
with IOL opacification was between hand movements and 0.6. Intraocular lens exchange is the only option
to treat this condition. Neodymium: YAG laser capsulotomy has been proposed as a method for cleaning
the IOL15; however, it remains unsuccessful. In addition, van Looveren and Tassignon16 concluded that an
Nd:YAG laser capsulotomy performed before IOL exchange adds an extra degree of difficulty to the
surgical procedure.
After implantation of an IOL, capsule contraction syndrome with anterior capsule opacification can result in
stretching of the zonular fibers and sometimes zonulysis, which canleadtoIOLdecentrationor dislocation.17
In our study, problems with capsular bag healing resulted in IOL decentration, contraction syndrome, or
IOL dislocation, which, after IOL opacification, were the 3 most frequent indications for IOL explantation.
Intraocular lens exchange is a challenging procedure. Meticulous dissection of the IOL from the capsular
bag using OVDs is mandatory. Several surgical techniques have been proposed in the literature. Our
technique includes cleaning the capsular bag thoroughly after the IOL is successfully removed from the
capsular bag. Capsular peeling will restore capsular bag integrity, which will give the most predictable
refractive outcome.11 This was recently confirmed by Gimbel and Venkataraman.12
Perioperative complications consisted of posterior capsule rupture, zonulysis, and vitreous loss. In the
cases of posterior capsule rupture, the IOL was positioned in the bag with or without a capsular tension
ring implanted in the sulcus, depending on the remaining capsule support. In our series, preoperative
Nd:YAG laser capsulotomy significantly compromised the surgical procedure. An anterior vitrectomy was
required in 18 of 37 cases having a preoperative Nd:YAG laser capsulotomy but in only 9 of 91 cases
without a preoperative Nd:YAG capsulotomy.
Ocular comorbidity (eg, diabetic retinopathy, chronic open-angle glaucoma, or age-related macular
degeneration) before IOL exchange can affect visual acuity improvement after IOL exchange. However,
final visual acuity improved significantly in our series, even in patients with perioperative or postoperative
complications.
In conclusion, IOL exchange was effective in patients with IOL opacification, decentration, or dislocation.
Impaired quality of vision due to mild capsule contraction, causing IOL decentration, was particularly
evident in patients with multifocal IOLs and accounted for 14% of the IOL exchanges. In the absence of
ocular comorbidity, the visual outcome was very good. Dissection of the IOL from the capsular bag and
meticulous peeling of the capsule are key to success.
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