SURGICAL OUTCOMES ACCORDING TO VITREOUS MANAGEMENT AFTER SCLERAL FIXATION OF POSTERIOR CHAMBER INTRAOCULAR LENSES BUM-JOO CHO, MD,* HYEONG GON YU, MD, PHD*† Purpose: To investigate the effect of vitreous management on surgical outcomes after scleral fixation of posterior chamber intraocular lenses. Methods: The medical records of 83 eyes from 83 patients, who underwent scleral fixation of posterior chamber intraocular lenses without any preexisting vitreoretinal complication and were followed up for $6 months, were reviewed retrospectively. Subjects were divided according to the strategy used for vitreous management into a pars plana vitrectomy (PPV) group (47 eyes) and an anterior vitrectomy (AV) group (36 eyes). Surgical outcomes were compared between the groups. Results: Both groups were comparable regarding demographics, follow-up period, and underlying ocular disease. The degree of visual improvement was similar in both groups (P = 0.911). Postoperatively, each group developed a myopic shift, which was greater in the PPV group than in the AV group (P = 0.040). Intraocular pressure elevations $25 mmHg occurred in 50% of eyes in the AV group and in 11% of eyes in the PPV group (P , 0.001). Intraocular lenses dislocated more frequently in the AV group (28%) than in the PPV group (9%; P = 0.036). Intraocular lens capture was more common in the PPV group (23%) than in the AV group (3%; P = 0.010). There was no significant difference in the rate of postoperative vitreoretinal complications. Conclusion: In eyes that received scleral fixation of posterior chamber intraocular lenses, PPV decreased the chances of postoperative intraocular pressure elevation and intraocular lens dislocation but increased the likelihood of intraocular lens capture and the magnitude of postoperative myopic shift. RETINA 34:1977–1984, 2014
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or more than 20 years, scleral fixation of posterior chamber intraocular lenses (SFPCIOL) has been widely used as an alternative to in-the-bag intraocular lens (IOL) implantation for patients with insufficient capsular support.1,2 The use of a sclerally fixated posterior chamber intraocular lens (PCIOL) as opposed to an anterior chamber IOL can reduce the degree of
damage to the corneal endothelium and anterior chamber angle.3 Many researchers have reported favorable visual outcomes and high rates of patient satisfaction after implantation with SFPCIOL.2–4 To ensure the success of SFPCIOL, vitreous management, which is necessary to prevent vitreous IOL attachment, must be approached cautiously.5 In many cases involving SFPCIOL, pars plana vitrectomy (PPV) is necessary because of the presence of a vitreoretinal complication such as a retinal detachment (RD) or an open-globe injury.6–8 In cases for which PPV is not compulsory, anterior vitrectomy (AV) has generally been preferred, because PPV is technically difficult and was reported to increase the risk of postoperative complications such as RD.9–11 However, some researchers have suggested that performing an AV through the limbal approach does not
From the *Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea; and †Sensory Organ Research Institute, Medical Research Center, Seoul National University, Seoul, Korea. Paper presented at the 109th Annual Meeting of Korean Ophthalmological Society, Goyang, Korea, April 21, 2013. None of the authors have any financial/conflicting interests to disclose. Reprint requests: Hyeong Gon Yu, MD, PhD, Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehang-no, Jongno-gu, Seoul 110-744, Korea; e-mail: [email protected]
1977
1978 RETINA, THE JOURNAL OF RETINAL AND VITREOUS DISEASES
result in the complete removal of the vitreous from the anterior chamber and ciliary sulcus, and thus causes entwinement of vitreous remnants around the IOL and consequent vitreoretinal traction.5,12 In addition, the results of previous studies that suggested higher complication rates in eyes treated with SFPCIOL combined with PPV may have been derived from selection bias inducing unfavorable surgical outcomes because of the inclusion of many eyes with advanced vitreoretinal complications.8,13 The aim of this study was to investigate the effects of vitreous management on surgical outcomes in eyes with SFPCIOL. To achieve this objective, we analyzed the surgical outcomes in eyes that received SFPCIOL without any previous or concurrent vitreoretinal complication. We divided the eyes into 2 groups according to the technique used for vitreous management, and compared the results in terms of visual outcomes and postoperative complications. Materials and Methods Subjects We retrospectively reviewed the medical records of a consecutive series of patients aged 18 or older who underwent SFPCIOL with either PPV or AV for the first time at Seoul National University Hospital during the period from January 1, 2002 to September 30, 2012. To minimize selection bias and the influence of preoperative vitreoretinal status on the surgical outcome, only eyes that did not have any previous or concurrent vitreoretinal complication and that were followed up for at least 6 months were included in the study. The exclusion criteria were as follows: 1) history of vitreoretinal disease (e.g., retinal break, RD, endophthalmitis, retinoschisis, or diabetic retinopathy) or open-globe injury (e.g., corneal or scleral laceration, penetrating keratoplasty); 2) history of vitrectomy or any type of retinal laser photocoagulation; 3) existence of a concurrent vitreoretinal complication (e.g., retinal break, RD, dislocation of PCIOL into the vitreous cavity) or open-globe injury; 4) combined penetrating keratoplasty or significant bullous keratopathy; 5) prophylactic intraoperative retinal laser photocoagulation; 6) sclerally fixated suturing of only one haptic or transscleral fixation in the pars plana rather than the ciliary sulcus; and 7) follow-up period ,6 months. When both eyes of the same patient met all study criteria, one eye was selected at random. Subjects were classified into two groups according to the method of vitreous management. In each case, PPV and AV were both feasible options, and the
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decision was made at the surgeon’s discretion after a discussion with the patient before surgery. The PPV group comprised of patients with SFPCIOL who underwent PPV for a complete vitrectomy, and the AV group included patients with SFPCIOL who underwent AV only. The study was approved by the Institutional Review Board and the Ethics Committee at Seoul National University Hospital. All investigations adhered to the tenets of the Declaration of Helsinki. Surgical Technique Pars plana vitrectomy or AV was performed before SFPCIOL by one of the multiple surgeons at Seoul National University Hospital. All patients from the PPV group underwent standard three-port PPV under general anesthesia or retrobulbar block. In each case, the surgeon attempted a complete vitrectomy that extended to the periphery. After the induction of posterior vitreous detachment, a core and peripheral vitrectomy was performed to remove as much vitreous as possible, especially at the vitreous base and ciliary body, where the PCIOL would be fixed in place. When necessary, a dislocated crystalline lens or lens capsule was removed. The peripheral retina was examined carefully under scleral indentation for any break. Sclerotomy sites were checked internally for any vitreous incarceration; any incarceration present was removed. In contrast, AV was performed using a bimanual port through a 2-mm clear corneal or limbal incision. After vitrectomy, a PCIOL was sclerally fixated using the same surgical method in both groups. A conjunctival peritomy was created, sometimes with half-thickness triangular scleral flaps. A double-armed 10-0 polypropylene suture with curved needles was inserted 1.5-mm posteriorly into the limbus using an ab externo technique. This suture was retrieved using a hollow 26-gauge needle, which was passed through the sclera in a similar fashion. Sutures were placed vertically, horizontally, or obliquely. The suture was hooked out of the eye through a corneal incision, cut, and then tied to each haptic of the PCIOL. The procedure was typically performed using an Acrysof MA60BM (Alcon Laboratories, Inc, Fort Worth, TX) or a YA60BBR (Hoya Healthcare Corp, Tokyo, Japan), which is a 3-piece foldable acrylic IOL without eyelets. The original IOL was repositioned in situ when possible or, alternately, extracted through a limbal incision and exchanged for a new IOL. In some cases, the power of IOL was reduced by 0.50 diopters (D) to compensate for the predicted myopic shift. Next, the haptics were drawn into the ciliary sulcus by
VITRECTOMY IN SCLERAL FIXATION OF PCIOL CHO AND YU
1979
pulling the polypropylene suture. After IOL centration was achieved by pulling the suture taut, each end of the polypropylene suture was used to create a knot beneath the scleral flap. The scleral flap was sutured using 10-0 nylon. In cases without scleral flaps, the suture knots were left long to prevent conjunctival erosion and suture exposure, then buried under the conjunctiva. Finally, the scleral three-port incisions and the conjunctiva were repaired with 7-0 polyglactin (Vicryl; Ethicon, Inc, Somerville, NJ). Clinical Outcome Measures The parameters assessed preoperatively included patient demographics, ophthalmic history, bestcorrected visual acuity, intraocular pressure (IOP), and target IOL power, as determined by biometric measurements obtained using the IOLMaster (Carl Zeiss Meditec, Jena, Germany) and the SRK-T formula.14 The parameters recorded postoperatively included best-corrected visual acuity, IOP, refractive error, and the existence of any complication, including IOP elevation, IOL dislocation or capture, suture exposure, cystoid macular edema (CME), and retinal break or detachment. Myopic shift was considered as follows: postoperative actual refractive error—preoperative target IOL power. In the case of a postoperative event affecting refractive error such as IOL dislocation, the last measurement of refractive error before the event was considered as the postoperative refractive error. Statistical Analysis Statistical analyses were performed using SPSS 20.0 for Windows (SPSS Inc, Chicago, IL). The distributions for continuous variables were expressed as mean ± standard deviation values. Independent t-tests, chisquare tests, and Fisher’s exact tests were used for comparisons related to age, sex, visual acuity, refractive outcome, and postoperative complications. A paired t-test was used to compare targeted and postoperative refractive error. The log-rank (Mantel–Cox) test was used for survival analysis of PCIOL dislocation. All statistical tests were 2-tailed, and statistical significance was defined by a P , 0.05. Results The study initially involved 437 eyes in subjects aged 18 or older scheduled to undergo SFPCIOL with PPV or AV for the first time. Detailed steps for the inclusion of subjects in this study are presented in Figure 1. Ultimately, 83 eyes from 83 patients were included.
Fig. 1. Participation flowchart of the eyes fitted with SFPCIOL. PK, penetrating keratoplasty.
Patient Demographics The mean subject age was 54.8 ± 15.6 years, 60 subjects (72%) were male and the mean follow-up period was 43.2 ± 31.0 months. Of 83 eyes, 47 (57%) were included in the PPV group and 36 (43%) were included in the AV group. The demographic characteristics of both groups are summarized in Table 1. The groups were comparable regarding age, gender, and the duration of postoperative follow-up. The underlying ocular diseases noted before SFPCIOL implantation included Marfan syndrome in 5 eyes (6%), glaucoma in 14 eyes (17%), and anterior uveitis in 6 eyes (7%). The most common indications for SFPCIOL were IOL dislocation (21 eyes, 45%) in the PPV group, and postsurgical aphakia with insufficient capsular support (21 eyes, 42%) in the AV group. The preoperative proportion of aphakic eyes was higher in the AV group than in the PPV group (P = 0.001). Visual and Refractive Outcomes The visual and refractive outcomes are presented in Table 2. Postoperative final best-corrected visual acuities were similar in both groups (P = 0.864), as were preoperative best-corrected visual acuities (P = 0.834). Visual acuity improved significantly in both groups after surgery (P , 0.001, for both groups). Poor postoperative visual acuities of 20/200 or worse occurred in only 7 eyes (8%). The degree of improvement was similar in both groups (P = 0.911). The mean target spherical equivalent was slightly more hyperopic in the PPV group than in the AV
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Table 1. Demographic Characteristics of Subjects Who Underwent Scleral Fixation of PCIOL PPV Group (n = 47), n (%)
AV Group (n = 36), n (%)
P
56.2 ± 12.6 34 (72) 18 (38) 41.1 ± 28.6
52.8 ± 18.8 26 (72) 19 (53) 45.9 ± 34.1
0.356* 0.990† 0.188† 0.503*
2 (4) 8 (17) 4 (9)
3 (8) 6 (17) 2 (6)
0.648‡ 0.966† 0.693‡
5 (11) 21 (45) 12 (26)
15 (42) 10 (28) 4 (11)
0.001† 0.115† 0.159‡
9 (19)
7 (19)
0.973†
Age, years Male gender Right eye Follow-up period, months Underlying disease Marfan syndrome Glaucoma Anterior uveitis Diagnosis Postsurgical aphakia Dislocation of the PCIOL Dislocation of the crystalline lens and/or zonular dialysis Complicated cataract surgery *Independent t-test. †Chi-square test. ‡Fisher’s exact test.
mmHg occurred more frequently in the AV group (50%) than in the PPV group (11%; P , 0.001). The IOP elevation was well managed with IOPlowering medication in all cases, with none requiring filtration surgery. In all cases, IOP was within the normal range at the final follow-up visit. Vitreous prolapse occurred in 11% of the patients with AV and none of the patients with PPV. Dislocation of the sutured PCIOL occurred more frequently in the AV group (28%) than in the PPV group (9%; P = 0.036). Intraocular lens dislocation was caused by suture breakage (6 eyes) or slippage of the haptic (2 eyes) in the AV group, and resulted from suture breakage (2 eyes) in the PPV group. The cause of IOL dislocation was not identified for the remaining eyes. Survival analysis for the patients with dislocated PCIOLs showed a marginally significant difference between the groups (P = 0.058, log-rank test). The time interval from surgery to IOL dislocation was 33.4 ± 20.0 months in the PPV group and 29.5 ± 37.4 months in the AV group (P = 0.848). Intraocular lens capture was significantly more common in the PPV group (23%; P = 0.010), requiring an additional surgery in 5 cases (45%). In the
group, but the difference was not statistically significant (P = 0.163). Mean postoperative final spherical equivalent was also similar in both groups (P = 0.330). Notably, both groups exhibited a significant myopic shift: −1.04 ± 1.17 D in the PPV group and −0.52 ± 0.80 D in the AV group (P , 0.001 and P = 0.001, respectively). The amount of myopic shift was significantly greater in the PPV group (P = 0.040). The mean amount of astigmatism was similar in both groups (−1.59 ± 1.07 D in the AV group and −1.76 ± 1.39 D in the PPV group, respectively; P = 0.584). In the five eyes with postoperative IOL tilting, the amount of astigmatism was −1.81 ± 0.75 D, which was similar to that observed in other members of the same group without IOL tilt (P = 0.626). Safety Outcomes An iatrogenic retinal break was created intraoperatively in 1 eye (2%) from the PPV group; the eye was treated with laser photocoagulation. Otherwise, no intraoperative complication developed in either group. The postoperative complications observed are presented in Table 3. Intraocular pressure elevation $25
Table 2. Visual and Refractive Outcomes After Scleral Fixation of PCIOL PPV Group (n = 47) Preoperative BCVA, logMAR Postoperative BCVA, logMAR Degree of visual improvement, logMAR Target refractive error, SE (D) Postoperative refractive error, SE (D) Myopic shift (D)
0.730 0.233 −0.486 −0.36 −1.43 −1.04
*Independent t-test. BCVA, best-corrected visual acuity; SE, spherical equivalent.
± ± ± ± ± ±
0.698 0.517 0.644 0.82 1.43 1.17
AV Group (n = 36) 0.767 0.254 −0.503 −0.62 −1.11 −0.52
± ± ± ± ± ±
0.864 0.629 0.677 0.84 1.21 0.80
P* 0.834 0.864 0.911 0.163 0.330 0.040
VITRECTOMY IN SCLERAL FIXATION OF PCIOL CHO AND YU
1981
Table 3. Postoperative Complications in Eyes After Scleral Fixation of PCIOL Postoperative Complications
PPV Group (n = 47), n (%)
IOP elevation $25 mmHg Vitreous prolapse Dislocation of PCIOL Pupillary capture of PCIOL optic Tilting of PCIOL CME Retinal break without RD Rhegmatogenous RD Vitreous hemorrhage Suture exposure
5 (11) 0 4 (9) 11 (23) 5 (11) 1 (2) 0 0 2 (4) 2 (4)
AV Group (n = 36), n (%) 18 4 10 1
(50) (11) (28) (3) 0 1 (3) 1 (3) 1 (3) 0 4 (11)
P ,0.001* 0.032† 0.036† 0.010† 0.066† 1.000† 0.434† 0.434† 0.503† 0.396†
*Chi-square test. †Fisher’s exact test.
remaining patients, the situation resolved spontaneously or after pupillary dilation in the supine position. Posterior chamber intraocular lens tilting was observed only in the PPV group, but the between-group difference was not statistically significant (P = 0.066). The AV group included one patient with RD and one patient with a retinal break, but there was no statistically significant difference between the groups (P = 0.434, respectively). Vitreous hemorrhage occurred in 2 eyes (4%) from the PPV group but not in the AV group (P = 0.503). In the PPV group, there was one patient with an epiretinal membrane. In 2 eyes (4%) from the PPV group and 4 eyes (11%) from the AV group, suture knots were exposed because of conjunctival erosion (P = 0.396). There was no difference in the rate of postoperative complications after secondary IOL implantation in aphakic eyes as compared with IOL implantation in nonaphakic eyes (P . 0.05 for any postoperative complication described above). There was no correlation between safety outcome and the type of IOL used, operating surgeon, or the decision to perform IOL rescue or IOL exchange (P . 0.05 for any postoperative complication described above).
Discussion The aim of this study was to determine the effect of vitreous management on surgical outcomes after SFPCIOL. The inclusion criteria were strictly controlled to minimize selection bias and the effect of preexisting vitreoretinal complications on surgical outcomes from the statistical analysis. The results showed that PPV decreased the chances of postoperative IOP elevation and IOL dislocation but increased the likelihood of IOL capture and the magnitude of myopic shift observed postoperatively. Notably, combined treatment with PPV as opposed to
AV and SFPCIOL implantation did not result in an increased rate of vitreoretinal complications. The most common postoperative complication after SFPCIOL was IOP elevation. Intraocular pressure increased in half of the patients with AV and in 11% of the patients with PPV, which is consistent with previous results.8,13,15 The higher incidence of IOP elevation in the AV group remains to be explained. Neither preexisting glaucoma nor vitreous prolapse into the anterior chamber was associated with IOP elevation in this study (P = 0.658 and P = 1.000, respectively). Some researchers have attributed elevations in IOP to the use of viscoelastic substance for AV.15 Regardless, increased IOP may not be a factor significantly over the long term, considering that all increases in IOP were managed effectively with antiglaucoma medication. However, IOP monitoring would be required during the immediate postoperative period, especially in patients with disks that could be susceptible to elevated IOP. Intraocular lens dislocation was the second most common complication and was more common in the AV group (28%) than in the PPV group (9%; P = 0.036). The incidence was comparable with that reported previously (12–48.7%).13,16,17 The dislocation of a sclerally fixated PCIOL can be caused by suture degradation or breakage, untying of the knot, slippage of the haptic from the suture, or erosion of the suture through the scleral tissue.18 The higher incidence of IOL dislocation in the AV group could imply the existence of physical stress on the IOL. Such pressure could be induced by contact between the residual vitreous and the IOL.5 To reduce the risk of IOL dislocation, complete removal of the vitreous surrounding the IOL by PPV is recommended. Intraocular lens capture was a major postoperative complication of PPV (23%) but not of AV (3%). The reason for this has not been elucidated yet, but the absence of a vitreous body could contribute to IOL
1982 RETINA, THE JOURNAL OF RETINAL AND VITREOUS DISEASES
instability and subsequent capture.3 Although the rate of IOL capture in eyes that underwent PPV with SFPCIOL was reported by Bading et al8 to be as low as 8% and by Johnston et al6 as 14.3%, these rates referred to the early postoperative period. In this study, the corresponding rate for a similar follow-up period was 11%, which was comparable with that reported in previous studies.6,8 Nevertheless, the decreased rate reported by Bading et al8 might reflect an increased distance between the point of fixation and the limbus (2 vs. 1.5 mm in this study). A previous study reported that a longer distance between the fixation point and the limbus can decrease the rate of IOL capture.19 Therefore, to prevent IOL capture, 2 mm, rather than 1.5 mm, might be recommended as the optimal distance of the fixation point from the limbus when SFPCIOL is combined with PPV. Otherwise, no specific intraoperative or preoperative risk factor for IOL capture such as floppy iris, was found in this study. The rate of IOL capture did not vary in procedures performed by different surgeons. Intraocular lens tilt was observed only in the PPV group. The frequency of IOL tilt is higher after SFPCIOL as compared with conventional IOL implantation because of the lack of sufficient capsular support20,21; the frequency increases in vitrectomized eyes.22 A surgical technique that allows for greater IOL stability such as four-point scleral fixation, would reduce the risk of IOL tilt or capture.23 Furthermore, exposure of the transscleral suture may increase the risk of endophthalmitis or accelerate suture breakage.2,3,13 Long-term suture exposure has been reported in 5% to 50% of patients in whom the suture is covered with the conjunctiva alone, and in 14.7% to 17.9% of patients with sutures covered by scleral flaps.3 In this study, the suture was carefully buried under Tenon’s capsule and the conjunctiva or under a scleral flap. This resulted in a low rate of exposure. The rate of RD after SFPCIOL without PPV has been reported to range from 1.1% to 4.9%,11,24 but the rate increased to 6.3% or 8.2% after SFPCIOL with PPV in several studies that included many eyes with preoperative vitreoretinal complications. A previous vitreoretinal complication could affect the risk of postoperative RD.8,13 Kim et al11 reported a higher rate of RD (8.46%) after SFPCIOL with PPV in eyes without a history of intraocular surgery, eyeball laceration, or PRP, and suggested that PPV is a risk factor for pseudophakic RD. In contrast, Johnston et al6 suggested that PPV before SFPCIOL may prevent future RD in eyes at a high risk. Hubbard et al25 recommended a complete vitrectomy to reduce the long-term risk of RD in patients with SFPCIOL. In this study, the rate of postoperative RD did not increase in the PPV
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group in eyes without any preexisting vitreoretinal complication. Retinal detachment developed in only 1 eye (3%) in the AV group. Although iatrogenic retinal breaks occurred intraoperatively in 2% of PPV eyes, PPV did not increase the risk of postoperative RD. Likewise, PPV did not affect the risk of any vitreoretinal complication in this study. The instances of postoperative vitreous hemorrhage observed were minor and transient; none required additional surgery. Although complete PPV was suggested to reduce the risk of CME, the condition developed at similar rates in both groups.22 The overall rates of vitreoretinal complications including RD, vitreous hemorrhage, and CME after SFPCIOL have been reported to be as high as 15% to 29%.6,8,19,26 This overall rate was reduced in this study (8%), perhaps because of the strict inclusion criteria. The reduced complication rate of the PPV group in this study indicates that many of the postoperative vitreoretinal complications in previous studies were attributable to preoperative comorbidities, not to the PPV itself. The rates of secondary surgical intervention (32%) were also lower than previously reported values (40–49%).6,13 The visual outcomes in this study were favorable and comparable between groups; the results were better than those of previous studies.8,11,13 Poor postoperative visual acuity was associated with glaucoma, preexisting amblyopia, or age-related macular degeneration. The causes of poor visual acuity reported in previous studies, such as corneal edema after AV with SFPCIOL,10 or RD and proliferative vitreoretinopathy after PPV with SFPCIOL, were less common among our patient population.6,8 This may be attributable to the exclusion of eyes with any preexisting vitreoretinal complication or significant bullous keratopathy before SFPCIOL implantation. Refractive error after SFPCIOL showed a postoperative myopic shift of −1.04 D in the PPV group and −0.52 D in the AV group. Previous studies reported myopic shifts of −0.65 D or −0.85 D after SFPCIOL implantation with AV, as compared with 0.08 D after in-the-bag IOL implantation.10,20 Hayashi et al20 suggested that SFPCIOL implantation results in reduced anterior chamber depth in comparison with in-the-bag IOL implantation, which induces a myopic shift. A complete vitrectomy might exacerbate any preexisting myopic shift. Many researchers have reported postoperative myopic shifts ranging from −0.1 to −0.5 D after cataract surgery combined with PPV.27–29 This postvitrectomy myopic shift was attributed to the increase in axial length that resulted from scleral thinning or stretching after vitrectomy.27 In summary, the myopic shift observed in the PPV group in this study may
VITRECTOMY IN SCLERAL FIXATION OF PCIOL CHO AND YU
represent the combined effects of SFPCIOL implantation and PPV. A similar amount of myopic shift (−1.0 D) was previously reported after SFPCIOL in aphakic vitrectomized eyes.30 Therefore, target IOL power should be adjusted for patients undergoing SFPCIOL with or without PPV to compensate for the predicted myopic shift. Pars plana vitrectomy is considered to have several advantages compared with AV in patients with SFPCIOL. First, PPV might prevent vitreous entwinement around a PCIOL by providing a much more thorough vitrectomy and capsulectomy.5 Tsunoda et al5 showed that considerable amounts of the vitreous were left behind in the ciliary sulcus after AV, especially when the vitreous cutter is inserted through a limbal incision, because the cutter does not reach the ciliary body. The residual vitreous or lens capsule fragments might induce IOL kinking, which would in turn result in vitreoretinal traction.5 Retinal tears, RD, CME, IOL dislocation, and other complications might ensue.3,5,11 However, this vitreous entwinement was absent when patients underwent a careful PPV and pars plana capsulectomy.5 Therefore, SFPCIOL implantation might require a complete vitrectomy around the surgical site.3,5 This approach would also allow for safe perioperative manipulation of the lens implant.12 Second, PPV might be beneficial in preventing vitreodonesis. In patients with SFPCIOL, because the lens-zonule barrier is absent, vitreodonesis or endophthalmodonesis can occur, inducing ocular instability leading to posterior vitreous detachment.31,32 Moreover, oscillations induced by saccadic eye movements may create turbulence in the aqueous humor and in areas of vitreous liquefaction.31 Both vitreodonesis and vitreal turbulence represent forms of mechanical trauma that can induce retinal complications such as macular edema, retinal breaks, and even RD.31 A nearcomplete PPV might prevent vitreodonesis. The threat of vitreous traction forces on the retina at the time of a future posterior vitreous detachment is also eliminated. The benefit of PPV in macular edema in patients with chronic aphakia has previously been reported.33 Third, PPV would be helpful in the management of combined vitreoretinal complications. In patients with an RD, vitreous hemorrhage, posteriorly dislocated IOL, or persistent intravitreal crystalline lens material after cataract surgery, PPV represents a safe treatment approach.22 Fourth, when PPV is performed, the peripheral retina can be inspected carefully, and prophylactic treatment can be applied to areas of tractional retinal tears or peripheral retinal degeneration.22 Thus, postoperative vitreoretinal complications could be prevented. Finally, the risk of postoperative
1983
vitreous-related complications such as epiretinal membrane formation and CME can be reduced by shaving the vitreous and removing all capsular elements. Because of recent advances in surgical instrumentation, 23-gauge and 25-gauge PPVs can reduce operation time and patient discomfort during surgery.11 Meticulous surgical management by an experienced surgeon will reduce the frequency of iatrogenic retinal breaks. Notably, this study has certain limitations. First, there is a possibility of selection bias because of the nonrandomized retrospective nature of investigation. As the performance of a combined PPV might imply a more complicated condition,11 strict inclusion criteria were used to minimize the selection bias in comparing the results of different groups. As a result, PPV and AV were both feasible options in each case, and the choice was decided at the surgeon’s discretion after a discussion with the patient. Nonetheless, there remains still a possibility of selection bias resulting from the surgeon’s preference. However, when we compared preoperative characteristics of two cohorts, there was no significant difference between the groups except the proportion of preoperative aphakic eyes. Furthermore, secondary IOL implantation in aphakic eyes did not show any difference in the rate of postoperative complications as compared with IOL implantation in nonaphakic eyes. However, a prospective randomized trial would be preferred to eliminate selection biases fundamentally. In addition, because operations were performed by multiple surgeons in this study, the difference in the expertness among surgeons could have affected the surgical outcomes. However, there was not a statistically significant difference in the postoperative complication rates among surgeons. However, this study represents 10 years of research at one of the biggest hospitals in the country. Although the proportion of eyes that underwent SFPCIOL implantation without any vitreoretinal complication was low, a rich database with data collected over many years allowed for the analysis of a large sample population. In conclusion, PPV and AV achieved similar success in terms of visual rehabilitation. Pars plana vitrectomy did not increase the likelihood of any postoperative complication other than IOL capture. Although the refractive outcomes showed a tendency toward myopic shift, the risk of certain complications, such as elevated IOP, IOL dislocation, and vitreous prolapse was reduced by the decision to perform a complete vitrectomy. Therefore, PPV can be considered even in eyes that do not have any preexisting vitreoretinal complication and are scheduled to undergo SFPCIOL implantation.
1984 RETINA, THE JOURNAL OF RETINAL AND VITREOUS DISEASES
Key words: pars plana vitrectomy, anterior vitrectomy, scleral fixation. References 1. Malbran ES, Malbran E Jr, Negri I. Lens guide suture for transport and fixation in secondary IOL implantation after intracapsular extraction. Int Ophthalmol 1986;9:151–160. 2. Holt DG, Young J, Stagg B, Ambati BK. Anterior chamber intraocular lens, sutured posterior chamber intraocular lens, or glued intraocular lens: where do we stand? Curr Opin Ophthalmol 2012;23:62–67. 3. Hannush SB. Sutured posterior chamber intraocular lenses: indications and procedure. Curr Opin Ophthalmol 2000;11: 233–240. 4. Price FW Jr, Wellemeyer M. Transscleral fixation of posterior chamber intraocular lenses. J Cataract Refract Surg 1995;21: 567–573. 5. Tsunoda K, Migita M, Nakashizuka T, Kohzuka T. Treatment of anterior vitreous before suturing an intraocular lens to the ciliary sulcus. J Cataract Refract Surg 1996;22:222–226. 6. Johnston RL, Charteris DG, Horgan SE, Cooling RJ. Combined pars plana vitrectomy and sutured posterior chamber implant. Arch Ophthalmol 2000;118:905–910. 7. Steinmetz RL, Brooks HL Jr, Newell CK. Management of posteriorly dislocated posterior chamber intraocular lenses by vitrectomy and pars plana removal. Retina 2004;24:556–559. 8. Bading G, Hillenkamp J, Sachs HG, et al. Long-term safety and functional outcome of combined pars plana vitrectomy and scleral-fixated sutured posterior chamber lens implantation. Am J Ophthalmol 2007;144:371–377. 9. Helal M, el Sayyad F, Elsherif Z, et al. Transscleral fixation of posterior chamber intraocular lenses in the absence of capsular support. J Cataract Refract Surg 1996;22:347–351. 10. Mimura T, Amano S, Sugiura T, et al. Refractive change after transscleral fixation of posterior chamber intraocular lenses in the absence of capsular support. Acta Ophthalmol Scand 2004; 82:544–546. 11. Kim SW, Kim MJ, Yang KS, et al. Risk factors for pseudophakic retinal detachment after intraocular lens scleral fixation with or without pars plana vitrectomy. Retina 2009;29:1479– 1485. 12. Nabors G, Varley MP, Charles S. Ciliary sulcus suturing of a posterior chamber intraocular lens. Ophthalmic Surg 1990; 21:263–265. 13. Vote BJ, Tranos P, Bunce C, et al. Long-term outcome of combined pars plana vitrectomy and scleral fixated sutured posterior chamber intraocular lens implantation. Am J Ophthalmol 2006;141:308–312. 14. Retzlaff JA, Sanders DR, Kraff MC. Development of the SRK/T intraocular lens implant power calculation formula. J Cataract Refract Surg 1990;16:333–340. 15. Krause L, Bechrakis NE, Heimann H, et al. Implantation of scleral fixated sutured posterior chamber lenses: a retrospective analysis of 119 cases. Int Ophthalmol 2009;29:207–212. 16. Smiddy WE. Management of dislocated foldable intraocular lenses. Retina 2005;25:576–580. 17. Zheng D, Wan P, Liang J, et al. Comparison of clinical outcomes between iris-fixated anterior chamber intraocular lenses
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and scleral-fixated posterior chamber intraocular lenses in Marfan syndrome with lens subluxation. Clin Exp Ophthalmol 2012;40:268–274. Price MO, Price FW Jr, Werner L, et al. Late dislocation of scleral-sutured posterior chamber intraocular lenses. J Cataract Refract Surg 2005;31:1320–1326. Ma DJ, Choi HJ, Kim MK, Wee WR. Clinical comparison of ciliary sulcus and pars plana locations for posterior chamber intraocular lens transscleral fixation. J Cataract Refract Surg 2011;37:1439–1446. Hayashi K, Hayashi H, Nakao F, Hayashi F. Intraocular lens tilt and decentration, anterior chamber depth, and refractive error after trans-scleral suture fixation surgery. Ophthalmology 1999;106:878–882. Durak A, Oner HF, Kocak N, Kaynak S. Tilt and decentration after primary and secondary transsclerally sutured posterior chamber intraocular lens implantation. J Cataract Refract Surg 2001;27:227–232. Johnston RL, Charteris DG. Pars plana vitrectomy and sutured posterior chamber lens implantation. Curr Opin Ophthalmol 2001;12:216–221. Almashad GY, Abdelrahman AM, Khattab HA, Samir A. Four-point scleral fixation of posterior chamber intraocular lenses without scleral flaps. Br J Ophthalmol 2010;94: 693–695. Lee JG, Lee JH, Chung H. Factors contributing to retinal detachment after transscleral fixation of posterior chamber intraocular lenses. J Cataract Refract Surg 1998;24: 697–702. Hubbard AD, Charteris DG, Cooling RJ. Vitreolensectomy in Marfan’s syndrome. Eye (Lond) 1998;12:412–416. Grigorian R, Chang J, Zarbin M, DelPriore L. A new technique for suture fixation of posterior chamber intraocular lenses that eliminates intraocular knots. Ophthalmology 2003;110:1349– 1356. Jeoung JW, Chung H, Yu HG. Factors influencing refractive outcomes after combined phacoemulsification and pars plana vitrectomy: results of a prospective study. J Cataract Refract Surg 2007;33:108–114. Falkner-Radler CI, Benesch T, Binder S. Accuracy of preoperative biometry in vitrectomy combined with cataract surgery for patients with epiretinal membranes and macular holes: results of a prospective controlled clinical trial. J Cataract Refract Surg 2008;34:1754–1760. Suzuki Y, Sakuraba T, Mizutani H, et al. Postoperative refractive error after simultaneous vitrectomy and cataract surgery. Ophthalmic Surg Lasers 2000;31:271–275. Ahn JK, Yu HG, Chung H, et al. Transscleral fixation of a foldable intraocular lens in aphakic vitrectomized eyes. J Cataract Refract Surg 2003;29:2390–2396. Binkhorst CD. Corneal and retinal complications after cataract extraction. The mechanical aspect of endophthalmodonesis. Ophthalmology 1980;87:609–617. Coonan P, Fung WE, Webster RG Jr, et al. The incidence of retinal detachment following extracapsular cataract extraction. A ten-year study. Ophthalmology 1985;92:1096–1101. Fung WE. Vitrectomy for chronic aphakic cystoid macular edema. Results of a national, collaborative, prospective, randomized investigation. Ophthalmology 1985;92:1102–1111.
F
or more than 20 years, scleral fixation of posterior chamber intraocular lenses (SFPCIOL) has been widely used as an alternative to in-the-bag intraocular lens (IOL) implantation for patients with insufficient capsular support.1,2 The use of a sclerally fixated posterior chamber intraocular lens (PCIOL) as opposed to an anterior chamber IOL can reduce the degree of
damage to the corneal endothelium and anterior chamber angle.3 Many researchers have reported favorable visual outcomes and high rates of patient satisfaction after implantation with SFPCIOL.2–4 To ensure the success of SFPCIOL, vitreous management, which is necessary to prevent vitreous IOL attachment, must be approached cautiously.5 In many cases involving SFPCIOL, pars plana vitrectomy (PPV) is necessary because of the presence of a vitreoretinal complication such as a retinal detachment (RD) or an open-globe injury.6–8 In cases for which PPV is not compulsory, anterior vitrectomy (AV) has generally been preferred, because PPV is technically difficult and was reported to increase the risk of postoperative complications such as RD.9–11 However, some researchers have suggested that performing an AV through the limbal approach does not
From the *Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea; and †Sensory Organ Research Institute, Medical Research Center, Seoul National University, Seoul, Korea. Paper presented at the 109th Annual Meeting of Korean Ophthalmological Society, Goyang, Korea, April 21, 2013. None of the authors have any financial/conflicting interests to disclose. Reprint requests: Hyeong Gon Yu, MD, PhD, Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehang-no, Jongno-gu, Seoul 110-744, Korea; e-mail: [email protected]
1977
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result in the complete removal of the vitreous from the anterior chamber and ciliary sulcus, and thus causes entwinement of vitreous remnants around the IOL and consequent vitreoretinal traction.5,12 In addition, the results of previous studies that suggested higher complication rates in eyes treated with SFPCIOL combined with PPV may have been derived from selection bias inducing unfavorable surgical outcomes because of the inclusion of many eyes with advanced vitreoretinal complications.8,13 The aim of this study was to investigate the effects of vitreous management on surgical outcomes in eyes with SFPCIOL. To achieve this objective, we analyzed the surgical outcomes in eyes that received SFPCIOL without any previous or concurrent vitreoretinal complication. We divided the eyes into 2 groups according to the technique used for vitreous management, and compared the results in terms of visual outcomes and postoperative complications. Materials and Methods Subjects We retrospectively reviewed the medical records of a consecutive series of patients aged 18 or older who underwent SFPCIOL with either PPV or AV for the first time at Seoul National University Hospital during the period from January 1, 2002 to September 30, 2012. To minimize selection bias and the influence of preoperative vitreoretinal status on the surgical outcome, only eyes that did not have any previous or concurrent vitreoretinal complication and that were followed up for at least 6 months were included in the study. The exclusion criteria were as follows: 1) history of vitreoretinal disease (e.g., retinal break, RD, endophthalmitis, retinoschisis, or diabetic retinopathy) or open-globe injury (e.g., corneal or scleral laceration, penetrating keratoplasty); 2) history of vitrectomy or any type of retinal laser photocoagulation; 3) existence of a concurrent vitreoretinal complication (e.g., retinal break, RD, dislocation of PCIOL into the vitreous cavity) or open-globe injury; 4) combined penetrating keratoplasty or significant bullous keratopathy; 5) prophylactic intraoperative retinal laser photocoagulation; 6) sclerally fixated suturing of only one haptic or transscleral fixation in the pars plana rather than the ciliary sulcus; and 7) follow-up period ,6 months. When both eyes of the same patient met all study criteria, one eye was selected at random. Subjects were classified into two groups according to the method of vitreous management. In each case, PPV and AV were both feasible options, and the
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decision was made at the surgeon’s discretion after a discussion with the patient before surgery. The PPV group comprised of patients with SFPCIOL who underwent PPV for a complete vitrectomy, and the AV group included patients with SFPCIOL who underwent AV only. The study was approved by the Institutional Review Board and the Ethics Committee at Seoul National University Hospital. All investigations adhered to the tenets of the Declaration of Helsinki. Surgical Technique Pars plana vitrectomy or AV was performed before SFPCIOL by one of the multiple surgeons at Seoul National University Hospital. All patients from the PPV group underwent standard three-port PPV under general anesthesia or retrobulbar block. In each case, the surgeon attempted a complete vitrectomy that extended to the periphery. After the induction of posterior vitreous detachment, a core and peripheral vitrectomy was performed to remove as much vitreous as possible, especially at the vitreous base and ciliary body, where the PCIOL would be fixed in place. When necessary, a dislocated crystalline lens or lens capsule was removed. The peripheral retina was examined carefully under scleral indentation for any break. Sclerotomy sites were checked internally for any vitreous incarceration; any incarceration present was removed. In contrast, AV was performed using a bimanual port through a 2-mm clear corneal or limbal incision. After vitrectomy, a PCIOL was sclerally fixated using the same surgical method in both groups. A conjunctival peritomy was created, sometimes with half-thickness triangular scleral flaps. A double-armed 10-0 polypropylene suture with curved needles was inserted 1.5-mm posteriorly into the limbus using an ab externo technique. This suture was retrieved using a hollow 26-gauge needle, which was passed through the sclera in a similar fashion. Sutures were placed vertically, horizontally, or obliquely. The suture was hooked out of the eye through a corneal incision, cut, and then tied to each haptic of the PCIOL. The procedure was typically performed using an Acrysof MA60BM (Alcon Laboratories, Inc, Fort Worth, TX) or a YA60BBR (Hoya Healthcare Corp, Tokyo, Japan), which is a 3-piece foldable acrylic IOL without eyelets. The original IOL was repositioned in situ when possible or, alternately, extracted through a limbal incision and exchanged for a new IOL. In some cases, the power of IOL was reduced by 0.50 diopters (D) to compensate for the predicted myopic shift. Next, the haptics were drawn into the ciliary sulcus by
VITRECTOMY IN SCLERAL FIXATION OF PCIOL CHO AND YU
1979
pulling the polypropylene suture. After IOL centration was achieved by pulling the suture taut, each end of the polypropylene suture was used to create a knot beneath the scleral flap. The scleral flap was sutured using 10-0 nylon. In cases without scleral flaps, the suture knots were left long to prevent conjunctival erosion and suture exposure, then buried under the conjunctiva. Finally, the scleral three-port incisions and the conjunctiva were repaired with 7-0 polyglactin (Vicryl; Ethicon, Inc, Somerville, NJ). Clinical Outcome Measures The parameters assessed preoperatively included patient demographics, ophthalmic history, bestcorrected visual acuity, intraocular pressure (IOP), and target IOL power, as determined by biometric measurements obtained using the IOLMaster (Carl Zeiss Meditec, Jena, Germany) and the SRK-T formula.14 The parameters recorded postoperatively included best-corrected visual acuity, IOP, refractive error, and the existence of any complication, including IOP elevation, IOL dislocation or capture, suture exposure, cystoid macular edema (CME), and retinal break or detachment. Myopic shift was considered as follows: postoperative actual refractive error—preoperative target IOL power. In the case of a postoperative event affecting refractive error such as IOL dislocation, the last measurement of refractive error before the event was considered as the postoperative refractive error. Statistical Analysis Statistical analyses were performed using SPSS 20.0 for Windows (SPSS Inc, Chicago, IL). The distributions for continuous variables were expressed as mean ± standard deviation values. Independent t-tests, chisquare tests, and Fisher’s exact tests were used for comparisons related to age, sex, visual acuity, refractive outcome, and postoperative complications. A paired t-test was used to compare targeted and postoperative refractive error. The log-rank (Mantel–Cox) test was used for survival analysis of PCIOL dislocation. All statistical tests were 2-tailed, and statistical significance was defined by a P , 0.05. Results The study initially involved 437 eyes in subjects aged 18 or older scheduled to undergo SFPCIOL with PPV or AV for the first time. Detailed steps for the inclusion of subjects in this study are presented in Figure 1. Ultimately, 83 eyes from 83 patients were included.
Fig. 1. Participation flowchart of the eyes fitted with SFPCIOL. PK, penetrating keratoplasty.
Patient Demographics The mean subject age was 54.8 ± 15.6 years, 60 subjects (72%) were male and the mean follow-up period was 43.2 ± 31.0 months. Of 83 eyes, 47 (57%) were included in the PPV group and 36 (43%) were included in the AV group. The demographic characteristics of both groups are summarized in Table 1. The groups were comparable regarding age, gender, and the duration of postoperative follow-up. The underlying ocular diseases noted before SFPCIOL implantation included Marfan syndrome in 5 eyes (6%), glaucoma in 14 eyes (17%), and anterior uveitis in 6 eyes (7%). The most common indications for SFPCIOL were IOL dislocation (21 eyes, 45%) in the PPV group, and postsurgical aphakia with insufficient capsular support (21 eyes, 42%) in the AV group. The preoperative proportion of aphakic eyes was higher in the AV group than in the PPV group (P = 0.001). Visual and Refractive Outcomes The visual and refractive outcomes are presented in Table 2. Postoperative final best-corrected visual acuities were similar in both groups (P = 0.864), as were preoperative best-corrected visual acuities (P = 0.834). Visual acuity improved significantly in both groups after surgery (P , 0.001, for both groups). Poor postoperative visual acuities of 20/200 or worse occurred in only 7 eyes (8%). The degree of improvement was similar in both groups (P = 0.911). The mean target spherical equivalent was slightly more hyperopic in the PPV group than in the AV
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Table 1. Demographic Characteristics of Subjects Who Underwent Scleral Fixation of PCIOL PPV Group (n = 47), n (%)
AV Group (n = 36), n (%)
P
56.2 ± 12.6 34 (72) 18 (38) 41.1 ± 28.6
52.8 ± 18.8 26 (72) 19 (53) 45.9 ± 34.1
0.356* 0.990† 0.188† 0.503*
2 (4) 8 (17) 4 (9)
3 (8) 6 (17) 2 (6)
0.648‡ 0.966† 0.693‡
5 (11) 21 (45) 12 (26)
15 (42) 10 (28) 4 (11)
0.001† 0.115† 0.159‡
9 (19)
7 (19)
0.973†
Age, years Male gender Right eye Follow-up period, months Underlying disease Marfan syndrome Glaucoma Anterior uveitis Diagnosis Postsurgical aphakia Dislocation of the PCIOL Dislocation of the crystalline lens and/or zonular dialysis Complicated cataract surgery *Independent t-test. †Chi-square test. ‡Fisher’s exact test.
mmHg occurred more frequently in the AV group (50%) than in the PPV group (11%; P , 0.001). The IOP elevation was well managed with IOPlowering medication in all cases, with none requiring filtration surgery. In all cases, IOP was within the normal range at the final follow-up visit. Vitreous prolapse occurred in 11% of the patients with AV and none of the patients with PPV. Dislocation of the sutured PCIOL occurred more frequently in the AV group (28%) than in the PPV group (9%; P = 0.036). Intraocular lens dislocation was caused by suture breakage (6 eyes) or slippage of the haptic (2 eyes) in the AV group, and resulted from suture breakage (2 eyes) in the PPV group. The cause of IOL dislocation was not identified for the remaining eyes. Survival analysis for the patients with dislocated PCIOLs showed a marginally significant difference between the groups (P = 0.058, log-rank test). The time interval from surgery to IOL dislocation was 33.4 ± 20.0 months in the PPV group and 29.5 ± 37.4 months in the AV group (P = 0.848). Intraocular lens capture was significantly more common in the PPV group (23%; P = 0.010), requiring an additional surgery in 5 cases (45%). In the
group, but the difference was not statistically significant (P = 0.163). Mean postoperative final spherical equivalent was also similar in both groups (P = 0.330). Notably, both groups exhibited a significant myopic shift: −1.04 ± 1.17 D in the PPV group and −0.52 ± 0.80 D in the AV group (P , 0.001 and P = 0.001, respectively). The amount of myopic shift was significantly greater in the PPV group (P = 0.040). The mean amount of astigmatism was similar in both groups (−1.59 ± 1.07 D in the AV group and −1.76 ± 1.39 D in the PPV group, respectively; P = 0.584). In the five eyes with postoperative IOL tilting, the amount of astigmatism was −1.81 ± 0.75 D, which was similar to that observed in other members of the same group without IOL tilt (P = 0.626). Safety Outcomes An iatrogenic retinal break was created intraoperatively in 1 eye (2%) from the PPV group; the eye was treated with laser photocoagulation. Otherwise, no intraoperative complication developed in either group. The postoperative complications observed are presented in Table 3. Intraocular pressure elevation $25
Table 2. Visual and Refractive Outcomes After Scleral Fixation of PCIOL PPV Group (n = 47) Preoperative BCVA, logMAR Postoperative BCVA, logMAR Degree of visual improvement, logMAR Target refractive error, SE (D) Postoperative refractive error, SE (D) Myopic shift (D)
0.730 0.233 −0.486 −0.36 −1.43 −1.04
*Independent t-test. BCVA, best-corrected visual acuity; SE, spherical equivalent.
± ± ± ± ± ±
0.698 0.517 0.644 0.82 1.43 1.17
AV Group (n = 36) 0.767 0.254 −0.503 −0.62 −1.11 −0.52
± ± ± ± ± ±
0.864 0.629 0.677 0.84 1.21 0.80
P* 0.834 0.864 0.911 0.163 0.330 0.040
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1981
Table 3. Postoperative Complications in Eyes After Scleral Fixation of PCIOL Postoperative Complications
PPV Group (n = 47), n (%)
IOP elevation $25 mmHg Vitreous prolapse Dislocation of PCIOL Pupillary capture of PCIOL optic Tilting of PCIOL CME Retinal break without RD Rhegmatogenous RD Vitreous hemorrhage Suture exposure
5 (11) 0 4 (9) 11 (23) 5 (11) 1 (2) 0 0 2 (4) 2 (4)
AV Group (n = 36), n (%) 18 4 10 1
(50) (11) (28) (3) 0 1 (3) 1 (3) 1 (3) 0 4 (11)
P ,0.001* 0.032† 0.036† 0.010† 0.066† 1.000† 0.434† 0.434† 0.503† 0.396†
*Chi-square test. †Fisher’s exact test.
remaining patients, the situation resolved spontaneously or after pupillary dilation in the supine position. Posterior chamber intraocular lens tilting was observed only in the PPV group, but the between-group difference was not statistically significant (P = 0.066). The AV group included one patient with RD and one patient with a retinal break, but there was no statistically significant difference between the groups (P = 0.434, respectively). Vitreous hemorrhage occurred in 2 eyes (4%) from the PPV group but not in the AV group (P = 0.503). In the PPV group, there was one patient with an epiretinal membrane. In 2 eyes (4%) from the PPV group and 4 eyes (11%) from the AV group, suture knots were exposed because of conjunctival erosion (P = 0.396). There was no difference in the rate of postoperative complications after secondary IOL implantation in aphakic eyes as compared with IOL implantation in nonaphakic eyes (P . 0.05 for any postoperative complication described above). There was no correlation between safety outcome and the type of IOL used, operating surgeon, or the decision to perform IOL rescue or IOL exchange (P . 0.05 for any postoperative complication described above).
Discussion The aim of this study was to determine the effect of vitreous management on surgical outcomes after SFPCIOL. The inclusion criteria were strictly controlled to minimize selection bias and the effect of preexisting vitreoretinal complications on surgical outcomes from the statistical analysis. The results showed that PPV decreased the chances of postoperative IOP elevation and IOL dislocation but increased the likelihood of IOL capture and the magnitude of myopic shift observed postoperatively. Notably, combined treatment with PPV as opposed to
AV and SFPCIOL implantation did not result in an increased rate of vitreoretinal complications. The most common postoperative complication after SFPCIOL was IOP elevation. Intraocular pressure increased in half of the patients with AV and in 11% of the patients with PPV, which is consistent with previous results.8,13,15 The higher incidence of IOP elevation in the AV group remains to be explained. Neither preexisting glaucoma nor vitreous prolapse into the anterior chamber was associated with IOP elevation in this study (P = 0.658 and P = 1.000, respectively). Some researchers have attributed elevations in IOP to the use of viscoelastic substance for AV.15 Regardless, increased IOP may not be a factor significantly over the long term, considering that all increases in IOP were managed effectively with antiglaucoma medication. However, IOP monitoring would be required during the immediate postoperative period, especially in patients with disks that could be susceptible to elevated IOP. Intraocular lens dislocation was the second most common complication and was more common in the AV group (28%) than in the PPV group (9%; P = 0.036). The incidence was comparable with that reported previously (12–48.7%).13,16,17 The dislocation of a sclerally fixated PCIOL can be caused by suture degradation or breakage, untying of the knot, slippage of the haptic from the suture, or erosion of the suture through the scleral tissue.18 The higher incidence of IOL dislocation in the AV group could imply the existence of physical stress on the IOL. Such pressure could be induced by contact between the residual vitreous and the IOL.5 To reduce the risk of IOL dislocation, complete removal of the vitreous surrounding the IOL by PPV is recommended. Intraocular lens capture was a major postoperative complication of PPV (23%) but not of AV (3%). The reason for this has not been elucidated yet, but the absence of a vitreous body could contribute to IOL
1982 RETINA, THE JOURNAL OF RETINAL AND VITREOUS DISEASES
instability and subsequent capture.3 Although the rate of IOL capture in eyes that underwent PPV with SFPCIOL was reported by Bading et al8 to be as low as 8% and by Johnston et al6 as 14.3%, these rates referred to the early postoperative period. In this study, the corresponding rate for a similar follow-up period was 11%, which was comparable with that reported in previous studies.6,8 Nevertheless, the decreased rate reported by Bading et al8 might reflect an increased distance between the point of fixation and the limbus (2 vs. 1.5 mm in this study). A previous study reported that a longer distance between the fixation point and the limbus can decrease the rate of IOL capture.19 Therefore, to prevent IOL capture, 2 mm, rather than 1.5 mm, might be recommended as the optimal distance of the fixation point from the limbus when SFPCIOL is combined with PPV. Otherwise, no specific intraoperative or preoperative risk factor for IOL capture such as floppy iris, was found in this study. The rate of IOL capture did not vary in procedures performed by different surgeons. Intraocular lens tilt was observed only in the PPV group. The frequency of IOL tilt is higher after SFPCIOL as compared with conventional IOL implantation because of the lack of sufficient capsular support20,21; the frequency increases in vitrectomized eyes.22 A surgical technique that allows for greater IOL stability such as four-point scleral fixation, would reduce the risk of IOL tilt or capture.23 Furthermore, exposure of the transscleral suture may increase the risk of endophthalmitis or accelerate suture breakage.2,3,13 Long-term suture exposure has been reported in 5% to 50% of patients in whom the suture is covered with the conjunctiva alone, and in 14.7% to 17.9% of patients with sutures covered by scleral flaps.3 In this study, the suture was carefully buried under Tenon’s capsule and the conjunctiva or under a scleral flap. This resulted in a low rate of exposure. The rate of RD after SFPCIOL without PPV has been reported to range from 1.1% to 4.9%,11,24 but the rate increased to 6.3% or 8.2% after SFPCIOL with PPV in several studies that included many eyes with preoperative vitreoretinal complications. A previous vitreoretinal complication could affect the risk of postoperative RD.8,13 Kim et al11 reported a higher rate of RD (8.46%) after SFPCIOL with PPV in eyes without a history of intraocular surgery, eyeball laceration, or PRP, and suggested that PPV is a risk factor for pseudophakic RD. In contrast, Johnston et al6 suggested that PPV before SFPCIOL may prevent future RD in eyes at a high risk. Hubbard et al25 recommended a complete vitrectomy to reduce the long-term risk of RD in patients with SFPCIOL. In this study, the rate of postoperative RD did not increase in the PPV
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group in eyes without any preexisting vitreoretinal complication. Retinal detachment developed in only 1 eye (3%) in the AV group. Although iatrogenic retinal breaks occurred intraoperatively in 2% of PPV eyes, PPV did not increase the risk of postoperative RD. Likewise, PPV did not affect the risk of any vitreoretinal complication in this study. The instances of postoperative vitreous hemorrhage observed were minor and transient; none required additional surgery. Although complete PPV was suggested to reduce the risk of CME, the condition developed at similar rates in both groups.22 The overall rates of vitreoretinal complications including RD, vitreous hemorrhage, and CME after SFPCIOL have been reported to be as high as 15% to 29%.6,8,19,26 This overall rate was reduced in this study (8%), perhaps because of the strict inclusion criteria. The reduced complication rate of the PPV group in this study indicates that many of the postoperative vitreoretinal complications in previous studies were attributable to preoperative comorbidities, not to the PPV itself. The rates of secondary surgical intervention (32%) were also lower than previously reported values (40–49%).6,13 The visual outcomes in this study were favorable and comparable between groups; the results were better than those of previous studies.8,11,13 Poor postoperative visual acuity was associated with glaucoma, preexisting amblyopia, or age-related macular degeneration. The causes of poor visual acuity reported in previous studies, such as corneal edema after AV with SFPCIOL,10 or RD and proliferative vitreoretinopathy after PPV with SFPCIOL, were less common among our patient population.6,8 This may be attributable to the exclusion of eyes with any preexisting vitreoretinal complication or significant bullous keratopathy before SFPCIOL implantation. Refractive error after SFPCIOL showed a postoperative myopic shift of −1.04 D in the PPV group and −0.52 D in the AV group. Previous studies reported myopic shifts of −0.65 D or −0.85 D after SFPCIOL implantation with AV, as compared with 0.08 D after in-the-bag IOL implantation.10,20 Hayashi et al20 suggested that SFPCIOL implantation results in reduced anterior chamber depth in comparison with in-the-bag IOL implantation, which induces a myopic shift. A complete vitrectomy might exacerbate any preexisting myopic shift. Many researchers have reported postoperative myopic shifts ranging from −0.1 to −0.5 D after cataract surgery combined with PPV.27–29 This postvitrectomy myopic shift was attributed to the increase in axial length that resulted from scleral thinning or stretching after vitrectomy.27 In summary, the myopic shift observed in the PPV group in this study may
VITRECTOMY IN SCLERAL FIXATION OF PCIOL CHO AND YU
represent the combined effects of SFPCIOL implantation and PPV. A similar amount of myopic shift (−1.0 D) was previously reported after SFPCIOL in aphakic vitrectomized eyes.30 Therefore, target IOL power should be adjusted for patients undergoing SFPCIOL with or without PPV to compensate for the predicted myopic shift. Pars plana vitrectomy is considered to have several advantages compared with AV in patients with SFPCIOL. First, PPV might prevent vitreous entwinement around a PCIOL by providing a much more thorough vitrectomy and capsulectomy.5 Tsunoda et al5 showed that considerable amounts of the vitreous were left behind in the ciliary sulcus after AV, especially when the vitreous cutter is inserted through a limbal incision, because the cutter does not reach the ciliary body. The residual vitreous or lens capsule fragments might induce IOL kinking, which would in turn result in vitreoretinal traction.5 Retinal tears, RD, CME, IOL dislocation, and other complications might ensue.3,5,11 However, this vitreous entwinement was absent when patients underwent a careful PPV and pars plana capsulectomy.5 Therefore, SFPCIOL implantation might require a complete vitrectomy around the surgical site.3,5 This approach would also allow for safe perioperative manipulation of the lens implant.12 Second, PPV might be beneficial in preventing vitreodonesis. In patients with SFPCIOL, because the lens-zonule barrier is absent, vitreodonesis or endophthalmodonesis can occur, inducing ocular instability leading to posterior vitreous detachment.31,32 Moreover, oscillations induced by saccadic eye movements may create turbulence in the aqueous humor and in areas of vitreous liquefaction.31 Both vitreodonesis and vitreal turbulence represent forms of mechanical trauma that can induce retinal complications such as macular edema, retinal breaks, and even RD.31 A nearcomplete PPV might prevent vitreodonesis. The threat of vitreous traction forces on the retina at the time of a future posterior vitreous detachment is also eliminated. The benefit of PPV in macular edema in patients with chronic aphakia has previously been reported.33 Third, PPV would be helpful in the management of combined vitreoretinal complications. In patients with an RD, vitreous hemorrhage, posteriorly dislocated IOL, or persistent intravitreal crystalline lens material after cataract surgery, PPV represents a safe treatment approach.22 Fourth, when PPV is performed, the peripheral retina can be inspected carefully, and prophylactic treatment can be applied to areas of tractional retinal tears or peripheral retinal degeneration.22 Thus, postoperative vitreoretinal complications could be prevented. Finally, the risk of postoperative
1983
vitreous-related complications such as epiretinal membrane formation and CME can be reduced by shaving the vitreous and removing all capsular elements. Because of recent advances in surgical instrumentation, 23-gauge and 25-gauge PPVs can reduce operation time and patient discomfort during surgery.11 Meticulous surgical management by an experienced surgeon will reduce the frequency of iatrogenic retinal breaks. Notably, this study has certain limitations. First, there is a possibility of selection bias because of the nonrandomized retrospective nature of investigation. As the performance of a combined PPV might imply a more complicated condition,11 strict inclusion criteria were used to minimize the selection bias in comparing the results of different groups. As a result, PPV and AV were both feasible options in each case, and the choice was decided at the surgeon’s discretion after a discussion with the patient. Nonetheless, there remains still a possibility of selection bias resulting from the surgeon’s preference. However, when we compared preoperative characteristics of two cohorts, there was no significant difference between the groups except the proportion of preoperative aphakic eyes. Furthermore, secondary IOL implantation in aphakic eyes did not show any difference in the rate of postoperative complications as compared with IOL implantation in nonaphakic eyes. However, a prospective randomized trial would be preferred to eliminate selection biases fundamentally. In addition, because operations were performed by multiple surgeons in this study, the difference in the expertness among surgeons could have affected the surgical outcomes. However, there was not a statistically significant difference in the postoperative complication rates among surgeons. However, this study represents 10 years of research at one of the biggest hospitals in the country. Although the proportion of eyes that underwent SFPCIOL implantation without any vitreoretinal complication was low, a rich database with data collected over many years allowed for the analysis of a large sample population. In conclusion, PPV and AV achieved similar success in terms of visual rehabilitation. Pars plana vitrectomy did not increase the likelihood of any postoperative complication other than IOL capture. Although the refractive outcomes showed a tendency toward myopic shift, the risk of certain complications, such as elevated IOP, IOL dislocation, and vitreous prolapse was reduced by the decision to perform a complete vitrectomy. Therefore, PPV can be considered even in eyes that do not have any preexisting vitreoretinal complication and are scheduled to undergo SFPCIOL implantation.
1984 RETINA, THE JOURNAL OF RETINAL AND VITREOUS DISEASES
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