Functional and anatomic outcome of scleral buckling versus primary vitrectomy in pseudophakic retinal detachment
Deependra Vikram Singh MD
Vitreo Retina Services
Dr Rajendra Prasad Centre for Ophthalmic Sciences
All India Institute of Medical Sciences
New Delhi 110029
Tel: + 91 11 2658 3193
Fax: + 91 11 2658 8919
Purpose: To conduct a randomized prospective clinical trial to compare primary vitrectomy without scleral buckling versus conventional scleral buckling surgery in pseudophakic primary retinal detachment (PPRD) in terms of anatomic attachment rate, functional outcome and complications.
Methods: Fifty consecutive eyes of 50 patients with PPRD were randomized into two groups, with 25 patients in each of group 1 (scleral buckling group) and group 2 (pars plana vitrectomy without buckling group) in a hospital setting and followed up at 1 week, 2 weeks, 6 weeks and 6 months.
Results: A primary reattachment rate of 76% (19 retinas) was obtained in group 1, while a reattachment rate of 84% (21 retinas) was achieved in group 2. The final anatomic reattachment rate was 100% in both groups. The causes of failure in group 1 were proliferative vitreoretinopathy in five eyes and open break/missed break in one eye. The causes of failure in group 2 were missed break/open break in three eyes and proliferative vitreoretinopathy in one eye. Best corrected visual acuity (BCVA) at 2 weeks was better in group 1, while the final BCVA at end of 6 months was two lines better in group 2. The mean change in refractive error was − 1.38 D in group 1 and − 0.85 D in group 2.
Conclusions: Pars plana vitrectomy without buckling provides an effective treatment for PPRD and results in better longterm visual and anatomic outcomes than conventional scleral buckling.
Retinal detachment (RD) after cataract surgery is an important problem that occurs in approximately 1% of eyes after cataract extraction and accounts for 25% of all retinal detachments (Javitt et al. 1991). Pseudophakic primary rhegmatogenous retinal detachment (PPRD) presents unique and difficult problems (Greven et al. 1992; Lois & Wong 2003). Published success rates for PPRD tend to be lower than for phakic retinal detachment (Braley & Osler 1955; Girard & Karpouzas 1995). Success rates for scleral buckling procedures in aphakic and pseudophakic retinal detachment vary between 61% and 77% (Braley & Osler 1955; Ho & Tolentino 1984; Greven et al. 1992). The reasons cited most often for these failures are compromised peripheral visibility secondary to pseudophakia, lens remnants and capsular opacities (Braley & Osler 1955; Ho & Tolentino 1984; Greven et al. 1992; Girard & Karpouzas 1995; Lois & Wong 2003).
A variety of methods, including conventional scleral buckling, primary pars plana vitrectomy, pars plana vitrectomy with scleral buckling, pneumatic retinopexy and temporary balloon tamponade have been used (Ho & Tolentino 1984; Tornambe et al. 1991; Greven et al. 1992; Yoshida et al. 1992; Gartry et al. 1993; Bartz-Schmidt et al. 1996; Campo et al. 1999). Primary scleral buckling is a particularly successful method of repair, but is associated with several complications, including reduced retinal blood flow, extrusion of the buckle, changes in refractory error, severe motility disturbances and postoperative pain (Ryan & Goldberg 1971; Rubin 1976; Arruga 1977; Yoshida et al. 1983). The indications for primary pars plana vitrectomy (PPV) in PPRD have continued to evolve with certain advantages over conventional scleral buckling (Arruga 1977; Heimann et al. 1996). Vitrectomy offers a direct approach for the relief of vitreo-retinal traction, removal of media opacities and detection of obscure retinal breaks. Campo et al. (1999) reported better anatomic and visual outcomes in PPRD treated with PPV alone and suggested that it is usually unnecessary to perform a scleral buckling procedure at the time of an optimal vitrectomy to repair non-proliferative vitreoretinopathy PPRD. Such combined therapy would appear to increase the chances of complications of scleral buckling without increasing the success rate (Campo et al. 1999).
We undertook this study to evaluate the role of primary pars plana vitrectomy as compared to conventional buckling surgery in the management of uncomplicated pseudophakic retinal detachment. To our knowledge, this is the first randomized prospective study to compare the two procedures.
Material and Methods
The protocol for the study was approved by the ethics committee of our hospital and conformed to the provisions of the 1995 Declaration of Helsinki (as revised in Edinburgh 2000).
A total of 50 eyes of 50 consecutive patients with uncomplicated PPRD were included in the study between January 2002 and December 2002. They were randomized to two groups, with 25 eyes in a scleral buckling (SB) group and 25 eyes in a pars plana vitrectomy without buckling (PPV) group. Exclusion criteria were proliferative vitreoretinopathy (PVR) grade C or worse, giant tear, multiple tears if located more than three clock hours apart, RDs with unseen breaks, macula on PPRDs, eye trauma, proliferative diabetic retinopathy, postoperative positioning untenable, previous intraocular surgery and children under the age of 16 years. The enrolled patients were randomized using random numbers to one of the two groups after they had given informed consent to participation in the study. Their best corrected visual acuity (BCVA) was measured with a Snellen chart at 6 metres and progressively decreasing distances (5 metres to 1 metre) in cases where the patient was unable to read the largest letter. The ability to appreciate hand movements at 0.5 metre was tested when BCVA was < 1/60. The Snellen BCVA was converted to decimal acuity for analysis. No patient had BCVA lower than hand movements, which was converted to 0.01 on the decimal scale. The ocular data included any incidence of myopia defined as less than − 1.0 D spherical equivalent and noted the presence of any Nd:YAG capsulotomy opening. Because the development of RD is associated with axial myopia, the refractive error prior to cataract surgery whenever available was included. Preoperative evaluation included applanation tonometry, slit-lamp biomicroscopy, indirect ophthalmoscopy with indentation and fundus photography and drawings to record the extent of RD and location of breaks (superior/inferior). The preoperative and postoperative spherical equivalents were calculated and compared for all eyes.
Surgery was performed in all the eyes under local peribulbar anaesthesia by a single surgeon (YRS). In the scleral buckling group, the breaks were localized, and limited scleral buckling (using a 7-mm grooved silicon tire) and encirclement (using a 2.5-mm silicone band) with cryopexy was performed around the breaks. External modified needle drainage (Azad et al. 1997) was carried out in all cases.
In the PPV group, all eyes underwent standard three-port pars plana vitrectomy. A complete vitrectomy was performed, including removal of anterior vitreous gel using scleral indentation. A meticulous search for peripheral retinal breaks in the periphery and central retina was carried out with the use of a wide-angle viewing system (Oculus 130; Oculus, Wetzler, Germany). Fluid air exchange with internal subretinal fluid drainage was performed through the pre-existing breaks in 13 cases and through the posterior retinotomy in 12 cases. Retinopexy was achieved by the diode laser endophotocoagulation around the break(s) and the retinotomy site. We used 14% C3F8 gas as the tamponading agent in all cases. No silicone oil/buckle was used in any case in the PPV group. Postoperative positioning was prescribed for at least 1 week.
Patients were followed up at 1 week, 2 weeks, 6 weeks, 3 months and 6 months for anatomic retinal reattachment, functional success and complications, with the final follow-up taking place at least 6 months after the last surgical procedure. Pars plana vitrectomy was performed in the failed cases in both the groups. Contingency tables were drawn for the various variables in the two groups and analysed using Pearson's chi-squared test. For continuous variables like intraocular pressure (IOP), Wilcoxon's sum rank test for statistical significance was used.
There was no statistically significant difference between the two groups with respect to preoperative factors such as age, sex, laterality, type of intraocular lens (IOL), duration of RD, PVR status, location of breaks (superior/inferior) and preoperative BCVA (Table 1). Both the SB and the PPV groups comprised 20 men (80%) and five women (20%). The mean age of the subjects in the SB group was 56.08 years (range 28–75 years), while in the PPV group the mean age was 58.28 years (range 42–70 years) (p = 0.43). The mean preoperative refractive error was 0.54 ± 0.77 D in the SB group and 0.42 ± 0.69 D in the PPV group, with the difference not being statistically significant (p = 0.56). The refractive error status prior to cataract surgery was available in 40 eyes (80%). Myopia < 1 D spherical equivalent was found in six eyes in the SB group and in five eyes in the PPV group. There was no statistical significance with regard to predisposing factors for RD (Nd:YAG posterior capsulotomy, myopia) between the two groups (p = 0.73).
Table 1. Characteristics of patients in scleral buckling and pars plana vitrectomy groups.
|Age mean ± SD||56.8 ± 12 years||58.28 ± 9.14 years||0.43|
|(Range)||(28–75 years)||(42–70 years)|| |
| Males||20 (80%)||20 (80%)||1.00|
| Females||5 (20%)||5 (20%)|| |
|Risk factors present||13 (52%)||11 (44%)||0.73|
| Nd:YAG capsulotomy||7||6|| |
| Myopia||5||3|| |
| Myopia + Nd:YAG capsulotomy||1||2|| |
|Type of cataract surgery||0.15|
| Extra capsular extraction||16 (64%)||15 (60%)|| |
| Phacoemulsification||9 (36%)||10 (40%)|| |
|Type of IOL|
| Posterior chamber IOL||23 (92%)||23 (92%)||1.00|
| Anterior chamber IOL||1 (4%)||1 (4%)|| |
| Iris clip IOL||1 (4%)||1 (4%)|| |
|Duration of RD; mean ± SD||27.8 ± 17.7 days||32.16 ± 19.37 days||0.89|
| (Range)||(5–90 days)||(4–100 days)|| |
|Configuration of RD|
| Total||17 (68%)||19 (76%)||0.72|
| Partial||8 (32%)||6 (24%)|| |
| Superior||16 62%)||18 (72%)|| |
| Inferior||9 (38%)||7 (28%)|| |
| Absent||15 (60%)||13 (32%)|| |
| Stage A/B||10 (40%)||12 (68%)|| |
In all, 16 eyes in the SB group and 15 eyes in the PPV group had undergone extra capsular cataract extraction and phacoemulsification was performed in nine eyes and 10 eyes in the SB and PPV groups, respectively. Posterior chamber IOLs were present in 92% (23 of 25 eyes) of cases in both groups. One eye in the SB group had an anterior chamber IOL and one eye in the PPV group had an iris-fixated IOL. The incidence of recurrent retinal detachment was not significantly associated with the type of cataract surgery in either group (p = 0.64 in the SB group and p = 0.53 in the PPV group).
Overall, 17 cases (68%) in the SB group and 19 cases (76%) in the PPV group had total RD; the rest of the cases had subtotal RD. Macula involvement appeared in all cases in both the groups. Fifteen cases (60%) in the SB group had no PVR, while 13 cases (52%) in the PPV group had no PVR (p = 0.89). The rest of the cases had PVR up to grade B. The majority of the cases in both the groups (i.e. 19 cases [76%] in the SB group and 21 cases [84%] in the PPV group) had initial BCVA of less than 3/60 (p = 0.648). The median initial BCVA in both groups was hand movements (HM) (SB group: range HM to 6/24; PPV group: range HM to 6/12).
A primary reattachment rate of 76% (19 retinas) was obtained in the SB group, while a reattachment rate of 84% (21 retinas) was achieved in the PPV group (p = 0.48). The mean duration at which redetachment was noticed was 12.5 ± 2.17 weeks in the SB group as compared to 9.0 ± 2.58 weeks in the PPV group, with the difference not being statistically significant (p = 0.077, paired-t-test). Pars plana vitrectomy was carried out in the failed cases in both groups. Proliferative vitreoretinopathy was responsible for 5/6 (83%) failed cases in the SB group, while 1/6 (17%) failed due to open break. Open break/new break was responsible for 3/4 (75%) failed cases in the PPV group, while 1/4 (25%) failed due to advanced PVR. C3F8 gas was used in nine cases, while silicone oil was used in one case with advanced PVR, where the retina was found to have attached at 8 weeks follow-up post silicone oil removal. The final anatomic reattachment rate was 100% in both groups, with an average of 1.24 procedures per eye in the SB group and 1.2 procedures per eye in the PPV group. Only one eye in the PPV group required more than two procedures.
In the SB group, BCVA improved from a preoperative median of HM (range HM to 6/24) to a median of 6/36 (range 6/60–6/12) at the end of the 3-month follow-up. Fifteen eyes (60%) in the SB group achieved an improvement of more than two lines of BCVA at the final follow-up. Nine eyes (35%) had retained preoperative BCVA and one eye (5%) had suffered a drop of one line of BCVA. In the PPV group, BCVA improved from a preoperative median of HM (range HM to 6/12) to a median of 6/18 (range 6/36–6/12) at the end of the 3-month follow-up. In this group, 20 eyes (80%) gained more than two lines of BCVA, while four eyes (15%) retained preoperative BCVA and 5% (one eye) suffered a drop of one line of BCVA. Table 2 shows the mean preoperative and mean postoperative BCVAs in the two groups. Best corrected VA at 2 weeks was better in the SB group, while the final VA was two lines better in the PPV group.
Table 2. Comparative evaluation of preoperative and postoperative BCVA in scleral buckling and pars plana vitrectomy groups.
|Preoperative||0.04 ± 0.05||0.06 ± 0.10||0.54|
|1 week||0.09 ± 0.10||0.03 ± 0.04||0.02*|
|2 weeks||0.10 ± 0.10||0.04 ± 0.05||0.032*|
|6 weeks||0.14 ± 0.15||0.18 ± 0.13||0.471|
|6 months/Last follow-up||0.19 ± 0.15||0.28 ± 0.12||0.034*|
The mean change in refractive error was − 1.38 D (range − 0.5 D to − 2.25 D) in the SB group and − 0.85 D (range − 0.25 D to − 1.0 D) in the PPV group, which was statistically significant in both groups (p = 0.016).
Both groups had few intraoperative and postoperative complications (Table 3). All of these complications except redetachment with PVR were managed medically and none required a surgical intervention. The raise in IOP was transient in the PPV group, except in one eye which developed intractable secondary glaucoma, for which a cyclodestructive procedure was performed (Table 4).
Table 3. Complications observed in the two groups.
|Needle perforation||1 (4%)||Iatrogenic breaks||6 (24%)|
|Hypotony||10 (40%)||Optic capture||1 (4%)|
|Retinal haemorrhage||2 (8%)||Retinal haemorrhage||1 (4%)|
|Residual RD||6 (24%)|| || |
|Choroidal detachment||2 (8%)||Hazy media||5 (20%)|
|Raised IOP||1 (4%)||Raised IOP||8 (32%)|
|Epithelial defect||1 (4%)||Epithelial defect||2 (8%)|
|Cellophane maculopathy||4 (16%)||Cellophane maculopathy||3 (12%)|
|Cystoid macular oedema||1 (4%)||Cystoid macular oedema||1 (4%)|
|Buckle infection||1 (4%)||PVR||1 (4%)|
|Diplopia||1 (4%)|| || |
|PVR||5 (20%)|| || |
Table 4. Comparative evaluation of preoperative and postoperative intraocular pressure (in mmHg) in scleral buckling and pars plana vitrectomy groups.
|Preoperative||4–24||(12.72 ± 4.81)||7–16||(11.52 ± 2.27)||0.244|
|1 week||12–24||(15.68 ± 3.90)||15–38||(22.16 ± 5.64)||< 0.001*|
|6 weeks||12–20||(14.16 ± 3.32)||14–24||(17.00 ± 3.96)||0.064|
|6 months||12–22||(14.64 ± 3.77)||12–22||(16.20 ± 3.63)||0.167|
We report the results of 50 consecutive cases of uncomplicated pseudophakic RD, enrolled from the vitreo-retina services during the period from January 2002 to December 2002 and randomized to scleral buckling versus PPV without scleral buckling. The stimulus for the above study came from previous studies in PPRD that had reported good results with primary vitrectomy alone (Campo et al. 1999). In addition, there have been somewhat disappointing results with conventional buckling procedure in the past with regard to anatomic and functional outcomes and complications, especially severe pain during surgery, anisometropia, motility disturbances, reduced retinal blood flow, anterior segment ischaemia, buckle infection and extrusion (Ryan & Goldberg 1971; Yoshida et al. 1983; Rubin 1976, Arruga 1977). Although the mean duration of RD was higher than in the previous studies (Ho & Tolentino 1984; Greven et al. 1992), the difference between the two groups was not statistically significant. Possibly, the patients did not seek medical advice until late in the course of the disease. Further, the duration was judged from the symptoms only, which may not necessarily correlate with the occurrence of RD.
In our series, we obtained primary anatomic success rates of 76% in the SB group and 84% in the PPV group; the difference in anatomic reattachment rates in the two groups was not statistically significant at the end of 6 months. Eventually all but one retina was attached in the second procedure. In other series of PPRD, reattachment rates of 62−77% after a single operation were reported (Greven et al. 1992; Ho & Tolentino 1984) and reattachment rates of 82−93% after several operations were reported (Yoshida et al. 1992). In these reports, conventional scleral buckling was performed in the majority of cases and PPV with scleral buckle was performed in selected cases.
Campo et al. (1999) reported anatomic success rates of 88% and 96% with PPV alone. The success rates of 76% and 84% with SB and PPV, respectively, in our study appear to be consistent with those reported in the literature.
The VA results in this series were also comparable to those reported in the literature. In this study the initial median BCVA in the SB group was HM and the final median BCVA was 6/36, while in the PPV group the initial median BCVA was HM and the final median BCVA was 6/18. The BCVA was better in the SB group at 2 weeks (p = 0.01), while the final BCVA at 6 months was two lines better in the PPV group (p = 0.03). This might be explained by the presence of C3F8 gas in the PPV group. The two lines better BCVA in the PPV group was as good as those in the published results. Our follow-up period of 6 months was less and might account for the low BCVA in the SB group. Best corrected VA at 2 weeks was significantly better in the SB group than in the PPV group. This was to be expected, considering the optical problems created by the C3F8 gas bubble. Thus, visual rehabilitation of the eyes in the SB group was significantly earlier compared to the eyes in the PPV group.
Although SF6 might have been a better choice for such a study, we used 14% C3F8 for intraocular tamponade. The reasons for using a long-acting gas were previous reports showing C3F8 as a better tamponade than SF6 for RRDs with severe PVR (Silicone Study 1992) and the fact that our previous experiences with SF6 for RRDs with minimal PVR had not been very encouraging.
The mean change in refractive error in the SB group was − 1.38 D, while in the PPV group it was − 0.85 D. The difference was statistically significant (p < 0.05) and is consistent with the results in literature (Rubin 1976; Campo et al. 1999). The refractive error resulting from vitrectomy can be attributed to focal changes in corneal curvature and also to the altered position of the IOL following surgery (Randleman et al. 2004). The intraoperative and late postoperative complications in the SB group were more than in PPV group. However, all the cases (excluding cases with redetachment and PVR) were successfully managed medically and none required a surgical intervention. Raised IOP was a major postoperative problem, especially in the PPV group. The raise in IOP was transient in the PPV group except in one eye, which developed intractable secondary glaucoma and required a cyclodestructive procedure. As a non-expansile concentration of C3F8 gas from a standard source was used, the cause of raised IOP could only be speculated upon. As a result of gas expansion, the early postoperative complications were more in the PPV group due to raised IOP. The raised IOP was transient and controlled by topical antiglaucoma medications or systemic carbonic anhydrase inhibitors, with no serious complications. Elevated IOP is a known complication following frequent fluid–gas exchange in vitrectomy (Bartz-Schmidt et al. 1996).
The causes of failure in the SB group were PVR in 5/6 (83%) failed eyes and open break in 1/6 (17%) failed eyes. The causes of failure in the PPV group were open break/new breaks in 3/4 (75%) failed eyes and PVR in 1/4 (25%) failed eyes. From the above fact it was evident that the predominant cause of failure in the SB group was PVR, while in the PPV group it was open break. The incidence of PVR in the PPV group was 4%, while in the SB group the incidence of PVR was 20%. The reported incidence of PVR after PPV varies from 6% to 9% (Ho & Tolentino 1984Campo et al. 1999). In our series the low incidence of PVR in the PPV group compared to that in the SB group may possibly be due to the removal of proliferative factors during vitrectomy.
Like any other study, this too had some limitations. Firstly, the Snellen distance VA converted to decimal acuity was used instead of logMAR BCVA, which has been found to differ significantly, with Snellen acuity exaggerating the visual loss (Li et al. 2002). Secondly, the exact durations of the two operative procedures were not compared, and, thirdly, the levels of patient discomfort during surgery and postoperatively were also not compared. While SB is expected to give more intraoperative and postoperative discomfort (pain, lid oedema), PPV is accompanied by the discomfort of postoperative positioning for at least 1 week. A discomfort scale designed to include all these factors and applied to test both procedures can help elucidate this problem.
The strong points of this study are its randomization of consecutive patients and the fact that possible confounding factors were either excluded (unseen breaks, macula on RDs, trauma, giant tears, multiple tears if located more than three clock hours apart) or found not to differ significantly between the two groups (age, myopia, Nd:YAG capsulotomy, location of breaks, type of surgery, IOL, preoperative PVR and duration of RD). In this small randomized series, we found that primary vitrectomy is at least as effective as scleral buckling in terms of reattachment rates following a single procedure, was associated with fewer complications and resulted in better final visual acuity at 6 months.
To conclude, conventional buckling surgery continues to be a time-tested and reliable procedure for PPRD. Therefore, if a vitreo-retinal set-up is not available, conventional scleral buckling surgery remains the surgery of choice. If a facility for advanced vitreous surgery is available, then the pars plana approach offers numerous advantages.