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Long-term outcome of scleral-fixated intraocular lens implantation
  1. Abbie S W Luk,
  2. Alvin L Young,
  3. Lulu L Cheng
  1. Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong
  1. Correspondence to Dr Alvin L Young, Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong; youngla{at}ha.org.hk

Abstract

Purpose Implantation of a scleral-fixated intraocular lens (SFIOL) for the surgical management of aphakia in the absence of capsular support is a safe procedure with a low risk of complications in the early postoperative period. However, data on long-term functional outcome are limited. The purpose of this study is to assess the long-term outcome and complication profile of SFIOL implantation in a cohort of Chinese patients.

Methods All patients who had undergone primary or secondary SFIOL implantation between 1997 and 2008 were retrospectively reviewed for visual outcomes and complications. Patients’ demographic data and information on baseline preoperative visual acuity, indication for surgery, postoperative complications, latest postoperative visual acuity and indication for any subsequent surgical procedures were collected and analysed.

Results 104 eyes of 99 patients (51 males and 48 females) were identified. Mean age at surgery was 67.1±13 years (range 32–88 years), with a mean follow-up of 73.4±43 months (range 12–180 months). 72% of patients had unchanged or improved final postoperative visual acuity. 25 of 104 eyes (24.0%) had postoperative complications, with suture-related complications being the most common. 13 eyes (12.5%) required further procedures for postoperative complications. Suture breakage leading to lens subluxation occurred in two eyes (1.9%).

Conclusions SFIOL implantation is valuable for the management of aphakia in the absence of capsular support, and our visual outcomes and complication rates are comparable to other case series. The long-term outcomes and safety profile are favourable, but potential long-term suture-related problems should be discussed with the patients before surgery.

  • Cornea
  • Lens and zonules
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Introduction

Implantation of scleral-fixated intraocular lens (SFIOL) is frequently performed in patients with aphakia in the absence of adequate capsular support. A theoretical advantage of SFIOL over anterior chamber intraocular lens (ACIOL) implantation is a reduced risk of corneal decompensation, cystoid macular oedema or glaucoma escalation.1 However, together with increased technical complexity and longer duration of surgery, additional risks in SFIOL implantation include suprachoroidal haemorrhage, vitreous haemorrhage and retinal detachment. Erosion or breakage of the sutures may also lead to lens tilt, dislocation of the SFIOL and risk of endophthalmitis.1 ,2 Primary ACIOL implantation has previously been compared with primary SFIOL implantation in a study by Kwong et al,3 who revealed no statistically significant differences in the complication profiles between the two methods. To date, multiple published case series have shown favourable short to mid-term outcomes for both primary and secondary SFIOL implantation. The purpose of our study was to evaluate in a Chinese population the long-term outcomes of a large series of patients who underwent SFIOL implantation.

Materials and methods

The medical records of patients who underwent SFIOL implantation and anterior vitrectomy in our university teaching hospital were analysed retrospectively. The study reviewed the records of consecutive patients who underwent surgery between 1997 and 2008 and had a minimum follow-up of 1 year. Institutional ethics approval was not required for this study. In addition to general demographic data, information on baseline preoperative visual acuity, indication for surgery, postoperative complications, latest best spectacle-corrected visual acuity (BSCVA) and indication for any subsequent surgical procedures was collected and analysed. Of the 162 patients whose medical records were reviewed, 63 were excluded from the study because they were followed up for less than 12 months or they were lost to follow-up.

Alcon CZ70BD lenses (Alcon Laboratories, Forth Worth, Texas, USA) were used for all SFIOL implantations. These were single piece polymethylmethacrylate (PMMA) lenses with eyelets and an optic diameter of 7.0 mm. For our ab externo SFIOL surgical technique, we made four entry sites for the intraocular lens (IOL) sutures and needles marked at 2 mm behind the limbus and 2 mm apart.4 10-O polypropylene sutures were used to secure the SFIOL in all eyes.

The Snellen BSCVA was converted into logarithm of the minimum angle of resolution (logMAR) units for statistical analysis.5 Patients with visual acuity of hand movement were arbitrarily assigned the equivalent of 1.7 logMAR units.3 The χ2 test was used for determining relationships between categorical variables, and the paired t test was used for normally distributed variables. All tests were considered to be statistically significant if the p value was 0.05 or less. Analysis was carried out using SPSS V.19.0 (SPSS, Chicago, Illinois, USA).

Results

A total of 104 eyes of 99 patients (51 males and 48 females) were identified and included in the analysis. Thirty eyes (28.8%) underwent primary SFIOL implantation, and 74 (71.2%) eyes underwent secondary implantation. In the primary SFIOL group, the SFIOL was implanted mostly because of posterior capsule complications during cataract surgery; extracapsular cataract extraction was performed in 10 eyes, phacoemulsification in 11 eyes, and intracapsular cataract extraction in nine eyes. In the secondary SFIOL group, indications for SFIOL implantation included a previous complicated cataract in 52 eyes, a subluxed IOL in five eyes, aphakia from previous traumatic cataract removal in 16 eyes, and aphakia due to previous removal of an IOL in one eye. The clinical characteristics and demographic details of the patients are summarised in table 1.

Table 1

Summary of patient demographics

The mean preoperative BSCVA was 0.8±0.58 logMAR units, which depended on any history of underlying ocular pathology prior to SFIOL implantation. Table 2 presents a summary of the visual outcome. Overall, 72.1% of patients had unchanged or improved final postoperative visual acuity, while 27.9% had reduced visual acuity compared to preoperative measurement. The mean difference between final postoperative and preoperative visual acuity was 0.3±0.6 logMAR units (95% CI 0.15 to 0.39; p<0.01), which was statistically significant. Further analysis comparing the mean difference between the primary and secondary SFIOL groups, while taking the preoperative BSCVA into consideration, showed no statistically significant difference (p=0.28).

Table 2

Summary of visual outcome

Overall, 25 of 104 eyes (24.0%) developed complications postoperatively, as summarised in table 3.

Table 3

Summary of complication profile

The most common were suture and corneal-related complications. Exposed polypropylene suture knots occurred in four eyes and required suture trimming or rotation within 1 year postoperatively, but did not cause any visual loss or necessitate further secondary procedures. Subluxed IOLs occurred in two eyes. In the first patient, this occurred after ocular trauma 7 years postoperatively, with subsequent pars plana vitrectomy and SFIOL re-fixation. The second patient developed subluxation of SFIOL on postoperative day 1. This patient had dementia with an unknown history of any ocular trauma; subsequent SFIOL removal and re-implantation was performed on day 1, and no further complications were noted during the follow-up period of 4 years.

Five eyes (4.8%) had significant corneal oedema or corneal decompensation postoperatively, however all five had prior preoperative risk factors for corneal decompensation: one eye had a known preoperative history of Fuchs’ dystrophy with a low endothelial cell count, two eyes had previous vitreo-retinal surgery before SFIOL implantation, one eye had a history of acute angle closure with mild corneal decompensation and a low endothelial cell count prior to SFIOL implantation, and the fifth eye had a history of previous ACIOL explantation after the development of haptic protrusion.

High intraocular pressure (IOP) requiring surgical intervention occurred in only three eyes (2.9%), which all had a history of traumatic cataract, with iridodialysis and peripheral anterior synechiae in two, and significant angle recession in one. Three eyes (2.9%) developed significant postoperative astigmatism requiring refractive surgery. In these three eyes, there was a prior history of ocular trauma requiring ruptured eye repair and traumatic cataract surgery. Laser in-situ keratomileusis correction was carried out in one eye with astigmatism of −7 dioptres, which reduced the astigmatism to −3.5 dioptres with a final postoperative visual acuity of 20/200. One eye underwent astigmatic keratotomy with subsequent reduction of astigmatism from −6 dioptres to −2.5 dioptres and latest visual acuity of 20/70. Another eye had known preoperative high astigmatism of −6 dioptres, which did not improve after SFIOL implantation and compression sutures, with latest visual acuity of 18/200. Retinal detachment only occurred in one eye after ocular trauma 9 months postoperatively and required vitreo-retinal surgery, which was complicated by bullous keratopathy at a later stage, with latest visual acuity of 20/200. Choroidal detachment occurred in one eye on postoperative day 1; this subsequently resolved spontaneously within 2 weeks postoperatively with latest visual acuity of 20/50.

Overall, 13 of 104 eyes (12.5%) required an additional surgical procedure postoperatively, as presented in table 4. Out of the 25 eyes with complications, 15 eyes (60.0%) had unchanged or improved visual acuity at the latest follow-up.

Table 4

Additional surgical procedures required postoperatively

Discussion

In the absence of capsular support, SFIOL implantation is an effective surgical option compared to the use of non-surgical IOLs or ACIOLs. However, this procedure does have some potential complications and technical complexities, which can be minimised with good patient selection and surgical experience. The aim of this study was to analyse the long-term visual outcomes and safety profile of a cohort of patients with primary or secondary SFIOL implantation. Overall, our results show favourable outcomes with best-corrected visual acuity improved or unchanged in 72.1% of eyes, which is similar to the visual outcomes reported in the literature.1 ,2 ,6

Corneal and suture-related problems were the most common postoperative complications. While elevated IOP requiring medical or surgical intervention occurred in only 2.9% of eyes in our study, it was more common in other case series. In a study by Donaldson et al7 comparing ACIOLs and sutured posterior chamber IOLs (PCIOLs), the most common complication in both types of lenses was elevated IOP. This was described as persistent IOP elevation of over 21 mm Hg for more than 3 months requiring medical intervention. In their sutured PCIOL cohort followed up for a mean duration of 18 months, elevated IOP occurred in 42% of eyes. Other complications including implant malposition occurred in 4%, suture erosion in 3%, and corneal oedema in 3%, which results are comparable to our study outcomes. In another retrospective analysis of scleral fixated PCIOLs by Krause et al,6 44% of cases had a transient rise in IOP as the most common postoperative complication. However, glaucoma escalation was reported to be zero in Belluci's case series, and 0.9% in a large case series by Lyle et al.8–10 These findings could be due to differences in preoperative demographics and prior glaucoma history, as well as differences in the definition of glaucoma as a postoperative complication, thus affecting reported occurrence. We define postoperative glaucoma as persistent elevated IOP of over 21 mm Hg requiring medical and surgical intervention; only 4.8% of our cases had documented pre-existing glaucoma.

The incidence of suture erosion differs between studies. Solomon et al11 reported an incidence of up to 73% in their retrospective series of 30 eyes over 23 months, while Uthoff et al reported an incidence of 17.9% in 624 patients after 1 year of follow-up.12 In a longer-term study by Vote et al, breakage of the polypropylene suture was found to be as high as 27% and the mean time from SFIOL implantation to suture breakage was 50 months.1 In our cohort, suture breakage only occurred in two of our cases (1.9%) over a mean follow-up period of 73 months. All our patients with SFIOL implantation had 10-O polypropylene sutures as 9-O is not routinely stocked in our hospital. The use of 9-O polypropylene sutures may potentially reduce suture-related complications due to its larger cross-sectional diameter and greater tensile strength compared to 10-O polypropylene. However, increased suture diameter size may require larger bore sclerostomies with the potential risk of leakage. The thicker suture is also technically more difficult to rotate and bury, and the knots if not buried may lead to erosion through the conjunctiva. In a series on dislocated scleral-sutured PCIOLs, Price et al noted microscopic degradation and surface cracks in the 10-O polypropylene suture remnants of explanted lenses.13 In addition to the use of 9-O polypropylene, they also recommend placement of the IOL haptics into the ciliary body or ciliary sulcus to promote scarring to help fixate the IOL. This may help to enhance the overall long-term stability of SFIOLs. Future long-term studies examining late dislocation or suture breakage rates between the two suture sizes will be useful to assess the superiority of 9-O.

Cumulatively, only 12.5% of eyes in our series required further surgical procedures, and many of these complications may have been related to a preoperative condition, such as prior ocular trauma or surgery. Many of the complications identified were infrequent and comparable in number to, if not less than, those in other case series reported in literature.1 ,2 ,8

In addition to ACIOLs, aphakic iris-fixated IOLs are also used for the correction of aphakia in eyes with insufficient capsular support. Excellent visual outcomes have been reported in a large review by Wagoner et al8 comparing secondary insertion of iris-fixated IOLs with ACIOLs and SFIOLs. A more recent study of 72 eyes in Chinese patients evaluating the 3-year outcome of secondary anterior iris-fixated IOLs also reported favourable outcomes with no serious complications noted during the period.14 Iris-fixated lens insertion may be less technically demanding than SFIOL implantation, and also avoids any suture-related complications. It is useful for patients with pre-existing glaucoma with trabeculectomies, where the surgeon may not want to disturb the conjunctiva. Although iris-fixated lens remain a promising alternative, to date better long-term outcomes have not been shown for iris-fixated lenses or ACIOLs compared to SFIOLs in the surgical management of aphakia.

Sutureless SFIOL implantation with intrascleral haptic fixation and glued IOL procedures have been gaining more recognition in recent years. Scharioth et al15 reported good intermediate results with no cases of recurrent dislocation or retinal detachment in a median follow-up of 7 months. In the glued IOL procedure described by Agarwal et al, surgical fibrin glue-sealant is used to secure the scleral flap and the externalised haptic to the scleral bed.16 The fibrin glue-assisted sutureless IOL scleral-fixation technique avoids the complexity of suturing and may also reduce complications such as pseudophakodonesis, persistent iris rubbing, and ciliary body needle damage.16 The 1-year follow-up study by Kumar et al17 of the glued IOL procedure showed good IOL centration outcomes with no major complications such as retinal detachment or endophthalmitis. This technique has also been adopted by vitreo-retinal surgeons in managing dropped lens to maintain a sutureless and closed chamber environment, with Lee et al18 reporting comparable short-term visual outcomes with scleral-fixation in their series of 31 eyes. However, long-term follow-up studies are lacking, and further studies comparing late complications such as IOL dislocation are warranted.

Limitations of this study are its retrospective and single-centre nature, variable lengths of follow-up and preoperative ocular history, and the use of different surgeons performing the surgeries. In our centre, there is a preference for secondary SFIOL implantation after a complicated cataract extraction, mainly to optimise the patient's ocular condition prior to lens implantation, performed by our more experienced cornea and external eye surgeons. Studies comparing primary and secondary SFIOL implantation do not conclusively demonstrate the superiority of either. A study by Lee et al19 suggests that secondary implantation may have lower early complication rates compared with primary, although final visual acuity and late complication rates were found not to be significantly different. Furthermore, future prospective study incorporating refractive data and corneal endothelial cell counts may also be beneficial.

In conclusion, the results of this study show excellent long-term visual outcomes and relatively low complication rates following primary or secondary SFIOL implantation in large cohort of Chinese eyes. Our study also shows a low suture breakage incidence over a mean follow-up of 6 years. Nevertheless, patients should be carefully informed during the consent process for SFIOL implantation of the potential complications and risk of secondary surgical procedures postoperatively, taking into consideration preoperative history and possible alternative non-surgical or surgical options.

References

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Footnotes

  • Contributors ASL initiated the project, implemented and completed the data collection, wrote the statistical analysis plan, analysed the data, and drafted and revised the paper. LLC contributed to the management of cases and revised the paper. ALY analysed the data, and drafted and revised the paper. He is guarantor.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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