Long-term outcome of scleral-fixated intraocular lens implantation without conjunctive peritomies or sclerotomy in ocular trauma patients


 Background

To investigate the long-term outcomes and complications of scleral-fixated intraocular lens (SFIOL) implantation without conjunctive peritomies or sclerotomy in patients with a history of ocular trauma during primary pars plana vitrectomy or silicone oil removal.

Methods

Records of patients who underwent implantation of SFIOL during primary pars plana vitrectomy or silicone oil removal.

Results

Sixty-nine eyes of 69 patients were included in this study. The median follow-up period was 34 months (range, 6-99 months). The average patient age at the time of surgery was 44 years old (range, 4-80 years). At the end of follow-up, the preoperative mean of best corrected visual acuity (BCVA) was 0.79 ± 0.86 log of the minimum angle of resolution (logMAR), which improved 0.20 ± 0.26 logMAR postoperatively (P = 0.01). BCVA improved or remained unchanged in 64 eyes (92.8%), VA decreased two lines in five eyes (7.2%). Early postoperative complications included transient corneal edema in seven eyes (10.1%), minor vitreous hemorrhage in four eyes (6.6%), transient elevated intraocular pressure (IOP) in one eye (1.4%), and hypotony in three eyes (4.3%). Late postoperative complications included persistent elevated IOP in five eyes (7.2%), epiretinal membrane formation in three eyes (4.3%), and cystoid macular edema noted in one eye (1.4%).

Conclusion

Use of a scleral-fixated intraocular lens implantation without conjunctive peritomies or sclerotomy in ocular trauma patients during either primary pars plana vitrectomy or second silicone oil removal is a valuable approach for the management of traumatic aphakia in the absence of capsular support.


Conclusion
Use of a scleral-fixated intraocular lens implantation without conjunctive peritomies or sclerotomy in ocular trauma patients during either primary pars plana vitrectomy or second silicone oil removal is a valuable approach for the management of traumatic aphakia in the absence of capsular support.

Background
Ocular trauma is one of the main causes of severe visual impairment. An estimated 18 million people worldwide suffer from ocular trauma each year [1]. Traumatic cataracts and lens dislocations are the most common and significant sequela of ocular trauma [2]. Nine percent of open-globe injuries result 3 in damage to the crystalline lens [3]. For eyes with post-traumatic cataracts or abnormal lens positions, lens removal surgery should be performed. In most cases, a traumatic cataract coincides with injury to the cornea, iris, ciliary body, retina, or sclera. Preoperative zonular defects and posterior capsular tears are also common. Therefore, management of ocular trauma patients with insufficient posterior capsular support or lens dislocation is complicated by multiple factors. Intraocular lens implantation is followed by removal of the lens. However, ocular trauma patients often have deficient capsular support and preoperative zonular defects. Scleral fixated intraocular lens (SFIOL) and anterior chamber intraocular lenses (ACIOLs) are alternative options to intraocular lens (IOL) implantation in eyes with inadequate capsular support. This can be performed as either a primary or secondary procedure [4].
The ACIOLs implantation can lead to a variety of complications, including corneal endothelial cell decompensation, cystoid macular edema, and glaucoma escalation [5]. SFIOL implantation therefore has some relative benefits. It reduces aniseikonia by positioning the lens further away from anterior segment structures like the corneal endothelium and trabecular meshwork. This minimizes the risk of corneal decompensation, peripheral anterior synechia, and secondary glaucoma [6,7].
Several SFIOL implantation techniques have recently been reported, which include burying the knot into either the scleral tunnel or scleral flaps [8,9] and using either Gore-tex [10] or 9-0 polypropylene sutures [11]. These innovative methods aim to reduce complications associated with sutures and intraocular lens tilt and decentration. Common to these techniques is the requirement for conjunctival dissection, scleral tunnel, or scleral flaps, all of which may increase surgical time, ocular injuries, and technical complexity.
We developed a scleral-fixated technique for SFIOL implantation in ocular trauma patients during primary pars plana vitrectomy (PPV) or secondary silicone oil removal. This obviates the need for external knot, scleral flaps, and conjunctival incision. It also requires less time than the other procedures, minimizing injury to anatomical structures of the post-traumatic eye. In this study, we evaluated the long-term visual outcomes of this technique in ocular trauma patients with insufficient capsular support or capsular defects during primary pars plana vitrectomy or secondary silicone oil 4 removal.

Methods
This retrospective study collected data from patients with a principal diagnosis of ocular trauma and either insufficient capsular support or capsular defect who underwent SFIOL during primary pars plana vitrectomy or secondary silicone oil removal in the Second Xiangya Hospital Ophthalmology Department between January, 2010 and March, 2018. The minimum follow-up period was six months.
The patients were selected for SFIOL surgery if their visual acuity improved correction. Approval was taken from the ethics committee at the Second Xiangya Hospital, Central South University. All clinical procedures were conducted in accordance with the ethical principles of the Declaration of Helsinki.
All patient data was collected from medical records and including general demographics, ocular trauma classification and distribution, the preoperative best corrected visual acuity (BCVA), surgical indication, lens conditions, type and refractive power of the implanted IOL, length of follow-up, and any indications for subsequent surgical procedures. The refractive power of the IOL was choice of the appropriate formula based on the axial length and corneal curvature of the eye. The VA was measured using a standard logarithmic visual acuity chart. The decimal unit for VA was converted to the log of the minimum angle of resolution (logMAR) for the statistical analysis. Counts of fingers and hand motions were converted to 2.00 logMAR and 2.30 logMAR, respectively. Light perception was converted to 3.00 logMAR [12].
Two surgical procedures were performed in this study: pars plana vitrectomy with primary SFIOL implantation following lensectomy or silicone oil removal surgery with secondary SFIOL implantation.
All procedures were performed by Baihua Chen using retrobulbar anesthesia. Three infusion cannulas were inserted through the superotemporal, inferotemporal, and superonasal sclera. Lensectomy was performed for traumatic cataracts and dislocated lenses. Pars plana vitrectomy was performed for vitreous hemorrhages, intraocular foreign bodies, and retinal detachments. The final implantation of the SFIOL was decided based on the retinal condition. For traumatic retinal detachment, a primary silicone oil tamponade was performed. The SFIOL was implanted during the removal of silicone oil.
The IOL was implanted and fixed to the posterior chamber using the minimally invasive knotless 5 technique described below. A needle with a 10-0 polypropylene loop suture was passed through the peripheral cornea and pulled through using a 27-guage guide needle inserted into the posterior chamber at either the 3 o'clock or 9 o'clock axis, 1.5mm from the limbus without conjunctive peritomies or sclerotomy ( Figure 1A, B). A 3.0 mm clear corneal tunnel incision was made in the superior temporal or nasal corneal limbus using a 3.0 mm blade to introduce the foldable IOL injector.
Polypropylene loop sutures were pulled from the corneal tunnel incision ( Figure 1C). A one-piece monofocal foldable IOL (Softec HD, Lenstec, Inc.) was injected into the anterior chamber. The foldable IOL remained within the injector while the first IOL haptic was sutured in place. In order to prevent the slippage of the suture and the inclination of the crystal, the suture is tied to the outside of the maximum radian in the middle of the IOL haptic on both sides, and a small groove is formed ( Figure   1D). The IOL was then injected into the posterior chamber and the other haptic was left outside the corneal incision. The second suture was successively looped around the other haptic, resulting in both haptics being tied by the polypropylene suture ( Figure 1E). The suture was tightened and the IOL position was adjusted in the posterior chamber. Afterward, the needle was passed through the existing scleral puncture site for a transscleral suture fixation. The needles moving between the scleral layers can be seen through the conjunctiva and fascia. The second needle is close to the suture, entering from the former needle outlet channel and suturing into the sclera layer, to ensure the passage of the second needle through the conjunctiva and fascia is the same as that of the previous needle through the conjunctiva and fascia. This maneuver was repeated three times leaving an S-shaped pattern fixed in the sclera. Last, the suture was cut without a knot ( Figure 1F). The clear corneal incision was closed with a watertight seal.
All patients were prescribed topical 1% prednisolone acetate, 0.5% levofloxacin, and mydriatic drops to be applied for a four-week postoperative period.
All patients received the following assessments on each follow-up visit: slit-lamp biomicroscopy measuring IOL centration, postoperative BCVA, corneal endothelial cell density, fundus evaluation, optical coherence tomography imaging (Heidelberg Engineering, Heidelberg, Germany) of the macula, manifest refraction, and intraocular pressure (IOP) measurements. Astigmatism caused by the IOL 6 was measured by a vectorial method [13].

SFIOL Tilt and Decentration Measurement
For all patients, postoperative SFIOL tilt and decentration were performed without pupillary dilation using ultrasound biomicroscopy (VisualSonics, Toronto, Ontario, Canada). A standardized ultrasound scan was performed. Image pro plus 6.0 (Media Cybernetics Inc., Rockville, MD, USA) was used to measure SFIOL tilt and decentration on ultrasound images ( Figure 2). Briefly, both horizontal and vertical images were used to calculate mean SFIOL tilt and decentration. The line between the anterior chamber angles was used as the reference line (L2). Two circles were then drawn to fit the anterior and posterior arc of SFIOL. The horizontal SFIOL line passed through the circle intersections (L1). SFIOL tilt was defined as the angle between the reference line and the SFIOL line. SFIOL decentration was defined as the horizontal distance between the midpoint of L1 and L2.
Statistical analyses were performed using SPSS (Version 22.0; IBM Corporation, Armonk, NY, USA) with statistical significance set at P ≤ .05. The BCVA is reported as mean ± SD and changes in BCVA were calculated using paired t-tests. The Wilcoxon signed-rank test was used to determine any significant differences between preoperative and postoperative BCVA or corneal endothelial cell density. Postoperative complications are expressed using numbers and percentages.

Results
The characteristics of the study population are shown in Table 1. Sixty-nine eyes of 69 patients are included. All patients were followed for at least six months and the mean follow-up duration was 34 months (range, 6-99 months). Of the 17(24.6%) female and 52 (75.4%) male patients, the mean age at the time of surgery was 44 years (range 4-80 years). Consistent with our previous study, the male population had a higher rate of traumatic injuries [14]. The operative eye was the right eye in 33 cases (47.8%) and the left eye in 36 cases (52.2%). Of these, 40 cases (60.0%) were traumatic aphakia.
These patients received primary pars plana vitrectomy and silicone oil tamponade, and were subsequently implanted with a SFIOL. Twenty-two eyes (29.8%) were traumatic cataracts with dislocation of crystalline lenses. Seven eyes (10.2%) were traumatic pseudophakic dislocations. A lensectomy and pars plana vitrectomy with primary SFIOL implantation was performed in 29 eyes 7 (40.0%), whereas silicone oil removal with secondary SFIOL implantation was performed in 40 eyes (60.0%). Table 2 shows the preoperative and postoperative visual outcomes. The mean preoperative BCVA was 0.79 ± 0.86 logMAR, which improved 0.20 ± 0.26 logMAR postoperatively (P = .01). The BCVA in 62 eyes (92.8%) improved or remained unchanged (loss of ≤ 1 line), and five eyes (7.2%) had a two-line decrease. The clinical characteristics of these five eyes are shown in Table 3. There was a statistically significant difference in BCVA between patients with corneal scars and those without (mean BCVA .08 and .20, P = .025). Patients with primary SFIOL implantation also had better visual outcomes than those with secondary SFIOL implantation (P = .037). The mean postoperative BCVA was comparable between open-globe injury and closed-globe injury patients. These mean BCVAs were 0.25 and 0.23, respectively (P = .106). The mean postoperative corneal endothelial cell density decreased from 2374 cells/mm 2 to 1999 cells/mm 2 (P < .01), and the rate of mean endothelial cell loss was 15% ± 8% at Horizontal tilt and decentration were 2.51 ± 1.42° and 0.43 ± 0.29 mm, respectively. Vertical tilt and decentration were 2.33 ± 2.10° and 0.39 ± 0.45 mm, respectively. There were no statistically significant differences between the open-globe injury group and the closed-globe injury group in SFIOL tilt and decentration (P = .803, P = .335, respectively). No difference was identified between the primary and secondary groups (P = .630, P = .610, respectively) for mean SFIOL tilt and decentration. Correlation assessments revealed no relationship between tilt and BCVA (P = .205).

Discussion
Traumatic cataracts and lens dislocation are the major causes of severe visual impairment after ocular trauma. The importance of vision rehabilitation in this population needs to be emphasized. In the setting of inadequate capsular support or capsular defects, SFIOL implantation is advantageous over other IOL implantation techniques. Although ACIOL implantation is easier to perform, it has a relatively higher rate of anterior segment complications, such as corneal endothelium decompensation, high intraocular pressure, hyphemia, and peripheral anterior synechia of the iris [6,15]. Furthermore, implantation of an ACIOL is not always possible due to defects in the iris and lack of vitreous support after pars plana vitrectomy in traumatic eyes. The SFIOL, in comparison, is implanted into the ciliary sulcus, which is the physiological location of the crystalline lens [16].
Several surgical approaches for SFIOL implantation have been proposed. All methods involve imbedding the suture knot under the scleral flap, in addition to other complex maneuvers [17,18] [19]. In addition, the technical difficulty of sutureless intrascleral PCIOLs implantation is correctly constructing the scleral tunnel, which requires a thick scleral tunnel for haptic insertion. The scleral tunnel must be parallel to the limbus to prevent tilt of the haptic. Excessive intraoperative grasping can lead to breakage and bending of the IOL haptic [13].
In this study, we demonstrate a new approach for transscleral IOL implantation involving minimally invasive knotless IOL fixation. The advantages of this approach go beyond those subsequently listed.
First, a 27-gauge needle is used to directly penetrate the ciliary sulcus without any conjunctival dissection or sclerotomy, which minimizes surgical manipulations and trauma to the ocular surface and sclera. This also does not require conjunctival dissection thus shortening operation time.
Conjunctival preservation is particularly desirable in this population, since prior or subsequent surgery may be required to control traumatic glaucoma, and because it reduces postoperative dry eye discomfort. Second, use of a foldable IOL contained in the injector reduces the size of the clear corneal incision, a crucial aspect of the technique that reduces the occurrence of surgically-induced corneal astigmatism [17]. Third and most importantly, the transscleral suture passing through the sclera can be rapidly fixed without any knots and thus precludes knot-related complications.
An important concern about the SFIOL is that suture erosion that may increase the risk of endophthalmitis. Imbedding the suture knot under the scleral flap is generally recommended. Some papers still report postoperative erosion of polypropylene sutures using this imbedding technique.
Solomon K et al. reported a 73% rate of suture erosion in their retrospective series of 30 eyes over 23 months [20], while Evereklioglu C et al. reported a suture erosion incidence of 7.8% in 51 patients during a 34 month follow-up [21]. A retrospective case series by Donaldson KE et al. also observed suture erosion in 3% of 181 patients; however, the follow-up period was only 14 months [22]. Although the suture-related complication rate differs from one study to another, data suggests that scleral flaps do not prevent suture erosion over the long-term [20]. The knotless technique was developed to reduce this risk, and no suture erosion was reported in any of our patients. The maximal follow-up time without erosion was 99 months.
Postoperative IOL dislocation depends on two aspects. Suture fixative IOL dislocation is often due to suture breakage or slippage, while sutureless IOL dislocation is mainly due to crystal slipping out of the scleral tunnel. The incidence of suture breakage differs between studies. Vote B et al. reported an incidence of 26.2% during a mean follow-up of six years. Longer follow-up was significantly associated with suture breakage [5]. In another study published by Kokame G et al., suture breakage was less than 0.5% during a mean follow-up of six years [23]. In addition, Kjeka O et al. found that no patients reported spontaneous dislocation of IOL due to suture breakage by the end of follow-up [24]. The safety and stability of suture fixation were associated with several factors, including the fixation technique, knot-tying technique, and suture type [23,25]. The 10-0 polypropylene suture demonstrated long-term stability for SFIOL implantation. Kokame GT et al. reported a maximum follow-up period for stable 10-0 polypropylene suture fixation of 24.75 years [23]. Here, we used double 10-0 polypropylene sutures for their durability and lower risk of suture-related complications.
We did not find suture breakage and spontaneous dislocation of IOL up to 99 months in our study, but long-term follow-up is still needed to determine their lifetime safety profile. A 9-0 polypropylene suture may reduce the potential risk of suture breakage, and some researchers using these for SFIOL reported 2.7% breakage (in 4 of 148 patients) with a mean follow-up of 23 ± 14 months [26].
However, determining the appropriate suture diameter is important to maintain the knot integrity.
Larger knots of 9-0 polypropylene are more likely to untie spontaneously and increase the risk of conjunctival erosion. Gore-Tex is a nonabsorbable, polytetrafluoroethylene monofilament suture with greater tensile strength than 10-0 polypropylene. Currently, Gore-Tex sutures are widely used for PCIOL fixation. Several studies indicate that Gore-Tex sutures are well-tolerated in PCIOL fixation patients and can decrease the risk of suture breakage [27,28]. Larger, randomized trials would be necessary to determine the relative risks and benefits of polypropylene over Gore-Tex sutures in PCIOLs fixation. respectively. The mean IOL tilt and decentration in our study were similar to previous studies [31][32][33].
In addition, there were no statistically significant differences between the open-globe and closedglobe injury groups in IOL tilt and decentration. Nevertheless, IOL tilt and decentration may result in significant astigmatism or higher-order aberrations after surgery [30,33]. Holladay et al. reported that spherical aberration resulting from anomalous IOL positioning was sufficient to decrease visual acuity when the decentration was more than 0.4 mm and the tilt was more than 7° [34]. The maximal SFIOL tilt and decentration in our patients was 4.41° and 1.20 mm, suggesting that the impact on the optic system is acceptably minor. Further studies are needed to assess the impact of IOL tilt and decentration on ocular trauma patients with suture-fixated PCIOLs implantation. Consequently, our SFIOL technique results in a more favorable IOL position in the posterior chamber.
Postoperative complications such as retinal detachment, suprachoroidal hemorrhage, corneal edema, and persistently elevated IOP have been reported [5,21,[35][36][37]. The most common postoperative complication in this series was transient corneal edema, which occurred in seven eyes (10.1%), an incidence similar to a previous study [38]. Additionally, corneal edema resolved within a week and no cases of corneal endothelial decompensation were reported. However, postoperative retinal detachment (RD) was not observed in any eye during the follow-up period. The peripheral retina was carefully examined and the lesion was pre-treated by laser photocoagulation after pars plana vitrectomy. Five eyes (7.2%) in our study developed persistently elevated IOP. Multiple mechanisms may be involved in the development of elevated IOP after ocular trauma, such as injury to trabecular meshwork, hyphemia, injury to the lens and/or iris, inflammation, peripheral anterior synechiae, vitreous hemorrhage, angle recession and topical corticosteroid use [39]. In cases of angle recession and coexisting lens subluxation, there may be an increased risk for secondary glaucoma [40]. Five eyes (7.2%) with persistently elevated IOP were treated with antiglaucomatous agents postoperatively. Four eyes had one or more quadrants of traumatic coloboma of the iris and angle recession. None of these postoperative complications resulted in significant worsening of final visual acuity. Our data suggests that minimally invasive knotless technique may be a good option for SFIOL placement in ocular traumatic patients.
Multiple mechanisms may be involved in corneal endothelial cell loss, such as poor IOL positioning, surgical trauma, and systemic diseases. Endothelial cell loss can also be caused by fluid turbulence during irrigation. In addition, pars plana vitrectomy with silicone oil tamponade resulted in decreased endothelial cell count [41]. There was a significant reduction in endothelial cells over the postoperative period (P < .05). The reported average rate for the annual loss of endothelial cells is approximately 0.3% to 0.5% [42]. We recognize that endothelial cell counts begin to stabilize about one year after surgery, a time point that may more accurately reflect the impact of this technique on endothelial cells. The mean postoperative corneal endothelial cell density decreased from 2374 cells/mm2 to 1999 cells/mm2 (P < .01) and the rate of mean endothelial cell loss was 15% ± 8% at 12 months. In general, silicone oil tamponade and operation time were significant risk factors for endothelial cell loss. Goezinne et al. reported reduced endothelial cell density one year after surgery when phacoemulsification with IOL implantation (19.2%) was performed on the eyes that underwent 13 pars plana vitrectomy with temporary silicone oil (SO) tamponade [43].
In order to prevent IOP fluctuation in the vitrectomized eye, intraocular perfusion was pre-placed. This approach not only maintains IOP stability, but may also prevent hypotony-related complications such as choroidal hemorrhage, shallow anterior chamber, and hypotony maculopathy. In addition, the small corneal incision makes it easier to maintain stable vitreous volume and IOP. In this study, pars plana vitrectomy was performed in all cases to treat traumatic retinal detachment or vitreous hemorrhage and to prevent retinal tear by vitreous traction.
Many studies have reported that PMMA structure of three-piece and one-piece IOLs were used as the SFIOL which was used by us before [44,45]. There are two methods to fix the PMMA structure of SFIOL including suture fixation and sutureless haptic buried in intrascleral tunnel. The first method has the following disadvantages: 1) Since the PMMA haptic is very smooth and hard, the knot on the haptic tends to slide easily, which will cause SFIOL to be eccentric or dislocated. 2) In order to prevent the knot on the haptic from slipping out, it is necessary to burn at the end of the PMMA haptic and produce a nodule. 3) The nodule may erode intraocular tissues. 4) It is need to open the conjunctiva and fascia and make the scleral flap. However, the second method also has the following disadvantages: 1) It is need to open the conjunctiva and fascia and make the scleral flap. There are also reports that they did not made scleral flaps and open conjunctiva and fascia. But It is difficult to ensure that the two haptics are strictly parallel in the scleral tunnel and located at the same distance behind the limbus. In addition, it is not easy to guide the second haptic into the scleral tunnel without opening the conjunctiva and fascia, and even to twist the haptic. 2) It is easy to twist haptics when it is pulled out of the eyeball with forceps. Sometimes, the twisted haptics cannot be restored. 3) In order to prevent IOL dislocation, it is often necessary to burn at the end of the PMMA haptics to form a nodule. On the contrary, we can avoid above problems by using a one-piece IOL. Firstly, a shallow groove can be formed by ligation on the haptics to prevent the suture from slipping off. Thus, it is also unnecessary to burn the end of the haptics. Secondly, haptics will not be deformed without picked up by forceps. Thirdly, we use double-line sutures to fix the IOL to reduce the probability of suture slippage and breakage. Fourthly, we did not open the conjunctiva and fascia to minimize ocular surface damage. Fifthly, there are not complications with knot. Finally, if we fixed the sutures at the both symmetrical points of the middle haptics, pulled the haptics just touching the ciliary sulcus, and completely removed the residual capsule and anterior vitreous body, it is easier to maintain the IOL balance and centralization ( Figure 4). Besides, a little study uses three or four haptics, but there are many disadvantages such as many incisions, increased damages, complex operative procedures, easy deformation of IOLs, eccentricity and so on [46].
Our minimally invasive knotless technique aims to improve visual outcomes, reduce the complications, stabilize IOL fixation, minimize ocular surface damage, and shorten operation time.
This technique precludes the need for conjunctival dissection, sclerotomy, or sutured wound closure.
Although the patient population had a complex variety of preexisting ocular conditions, the preoperative to postoperative BCVA was statistically significant. (P = .01). After a long-term, 34 months follow-up, there was no evidence of significant SFIOL decentration or severe complications.
We also applied this technique to non-traumatic aphakic eyes without adequate capsule support, and the same results were obtained. These data were not included in this study.

Conclusions
Our SFIOL technique may be useful for IOL implantation in aphakic eyes due to traumatic or other causes with insufficient capsule support, and provides good visual outcomes as well as stable IOL fixation. We believe this technique is a good option for SFIOL because the simple and rapid maneuver obviates the need for sclerotomy or conjunctival dissection and stably fixes the IOL in the sclera.