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]. The major concerns regarding knotted techniques are conjunctival and scleral erosion, which can eventually lead to endophthalmitis. The sutureless intrascleral PCIOL implantation technique was designed to eliminate such suture-related complications. Kumar DA et al. have reviewed complications in 486 eyes that underwent sutureless IOL implantation. The IOL haptic-related complications arising from this sutureless technique are haptic displacement (4.1%), haptic tip extrusion (0.8%), and subconjunctival haptic (0.4%)[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.
Tilt and decentration are important predictors of accurate IOL positioning. Unlike intracapsular IOL fixation, the IOL was fixed with suture techniques, which may increase the likelihood of IOL tilt and decentration. De Castro A et al. reported an average tilt angle of 2.6° and decentration length of 0.4 mm in cases of in-the-bag IOLs[29]. Oshika T et al reported a tilt and decentration for scleral-sutured IOLs of 4.43 ± 3.02° and 0.279 ± 0.162 mm, respectively, which is significantly higher than those of intracapsular IOLs[30]. Zhu X et al. evaluated tilt and decentration after sutured PCIOLs implantation in patients with open globe injuries. The horizontal tilt and decentration were 1.73 ± 1.54° and 0.47 ± 0.40 mm, respectively. The vertical tilt and decentration were 2.33 ± 2.10° and 0.39 ± 0.45 mm, respectively. The mean IOL tilt and decentration in our study were similar to previous studies[31-33]. In addition, there were no statistically significant differences between the open-globe and closed-globe 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, 35-37]. 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 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.