Prognostic Factors for Recurrent Rhegmatogenous Retinal Detachment after Silicone Oil Removal
Article information
Abstract
Purpose
To investigate the prognostic factors for recurrent rhegmatogenous retinal detachment following silicone oil removal.
Methods
This retrospective review included 147 consecutive patients with rhegmatogenous retinal detachment treated with silicone oil tamponade at a high-volume referral-based tertiary hospital between January 2012 and May 2022. All patients underwent follow-up for a minimum of 6 months after subsequent silicone oil removal. The primary outcome measure was the rate of recurrent retinal detachment following silicone oil removal, and the secondary outcome was best-corrected visual acuity after silicone oil removal.
Results
The mean silicone oil tamponade duration was 4.7 ± 5.01 months (range, 1–38 months; median, 3 months), and the recurrent retinal detachment rate after silicone oil removal was 15.6%. Logistic regression analysis revealed that argon endolaser photocoagulation during silicone oil removal (odds ratio [OR], 0.309; 95% confidence interval [CI], 0.106–0.898; p = 0.031) was associated with a lower rate of anatomical success after silicone oil removal. Demographics, preoperative ocular characteristics, proliferative vitreoretinopathy, previous scleral encircling or buckling, previous retinectomy, concomitant phacoemulsification, duration of silicone oil tamponade, and gas tamponade after silicone oil removal were not significantly associated with recurrent retinal redetachment after silicone oil removal. Duration of silicone oil tamponade (OR, 1.226; 95% CI, 1.073–1.402; p = 0.003) and recurrent retinal detachment after silicone oil removal (OR, 3.400; 95% CI, 1.311–8.817; p = 0.012) were associated with poor visual outcomes after silicone oil removal.
Conclusions
Among all factors examined in this study, including the duration of silicone oil tamponade, laser retinopexy was the only significant prognostic factor for recurrent retinal detachment after silicone oil removal. A longer duration of silicone oil tamponade was associated with worse visual outcomes and a lower rate of visual improvement after silicone oil removal.
Silicone oil has been widely used as a valuable tool for treating complex rhegmatogenous retinal detachment (RRD) since its introduction as a tamponade agent in the early 1960s [1]. Silicone oil is preferred for treating proliferative vitreoretinopathy (PVR) because it rapidly stabilizes the eye, provides extended tamponade, and effectively controls challenging clinical situations compared to that with the longer acting gas octafluorocyclobutane (C3F8) [2]. Although silicone oil can be left in place permanently, it is often removed because of complications such as poor vision due to its refractive index [3], glaucoma, silicone oil in the anterior chamber, chronic hypotony, cataract formation, emulsification, and keratopathy [4,5]. However, recurrent RD can occur after silicone oil removal.
Few studies have identified risk factors associated with recurrent RD after silicone oil removal. Some studies have suggested prophylactic 360° laser treatment is a protective factor against recurrent RD [6–9]. However, studies on effectiveness of prophylactic scleral buckling to prevent redetachment after silicone oil removal have yielded conflicting results [10–13]. Similarly, studies on prolonging the duration of silicone oil tamponade to reduce recurrent RD rates have shown conflicting results [10,12,14,15]. Despite the heightened risk of complications associated with an extended duration of silicone oil tamponade [16], the timing of silicone oil removal remains a matter of clinical judgement.
This study evaluated the prognostic factors, including the duration of silicone oil tamponade, influencing the recurrent RD rate after silicone oil removal in patients who underwent vitrectomy and silicone oil tamponade for RRD. Furthermore, we evaluated potential prognostic factors influencing long-term visual outcomes.
Materials and Methods
Ethics statement
This study was approved by the Institutional Review Board of Severance Hospital (No. 4-2023-1584). The study adhered to the principles outlined in the Declaration of Helsinki. The requirement for informed consent was waived due to the retrospective nature of the study.
Study population
This retrospective study reviewed the medical records of patients who underwent silicone oil tamponade for the treatment of RRD at Severance Hospital (Seoul, Korea), between January 2012 and May 2022. Patients who underwent silicone oil removal and had a minimum follow-up of 6 months after removal were included in the analysis. Eyes with proliferative diabetic retinopathy, traumatic RD, or silicone oil tamponade for <1 month were excluded.
Data collected from medical records included patient age and sex, axial length, duration of silicone oil tamponade, presence of PVR during initial RD repair, presence of PVR within 3 months after silicone oil removal, presence of partial detachment before silicone oil removal, lens status before silicone oil removal (phakic, pseudophakic, aphakic), size of RD before the primary operation, and concomitant surgical procedures performed during the primary operation (retinectomy, scleral buckling or encircling). Additionally, data on concomitant surgical procedures performed during silicone oil removal (endolaser photocoagulation, cataract surgery or secondary intraocular lens implantation, and gas or air tamponade), number of silicone oil exchanges performed before oil removal, partial detachment immediately after silicone oil removal, anatomic success, and Snellen best-corrected visual acuity (BCVA) before and after silicone oil removal (at the patient’s most recent visit) were collected.
Definitions
Axial lengths were measured using Axial lengths were measured using IOL Master 700 (Carl Zeiss Meditec) and A-scan ultrasonography (Ellex). Eyes were classified into short and long axial lengths, with a cutoff value of 27.0 mm. This specific cutoff value was chosen as it aligns with the commonly used definition of high myopia [10,17–19].
RD was diagnosed using an Optos Ultra-Widefield Fundus Camera (Optos California) and spectral domain optical coherence tomography (OCT; Spectralis Heidelberg retina angiograph + OCT, Heidelberg Engineering) (Fig. 1A–1E). The extent of RD was classified as large (≤2 quadrants) or giant (>2 quadrants) according to Thompson et al. [20,21], who reported that reattachment rates for grade 3 detachments (breaks confined to two quadrants and/or three or more quadrants of RD) were lower than those of grade 1 or 2 detachments (grade 2, single or multiple breaks within the same quadrant and/or less than two quadrants of RD).
A representative case of a recurrent retinal detachment after silicone oil removal. A 73-year-old woman with recurrent retinal detachment 4 months after silicone oil removal with concomitant endolaser photocoagulation. Trans pars plana vitrectomy with endolaser barrier and silicone oil injection was performed for initial rhegmatogenous retinal detachment repair. The silicone oil was removed after 3 months of tamponade. Right eye multimodal evaluation: (A,B) Widefield fundus photography and optical coherence tomography before silicone oil removal show a well-attached retina after silicone oil tamponade. (C) One month after silicone oil removal, a well-attached retina with an added barrier at the inferior periphery is observed on fundus photography. (D,E) Recurrent retinal detachment involving the macula starting from the inferonasal quadrant is observed on fundus photography and optical coherence tomography 4 months after silicone oil removal.
The BCVA before and after surgery was obtained from the medical records. BCVA was measured using the Snellen visual acuity chart and converted into the logarithm of the minimum angle of resolution (logMAR) units for analysis. Postoperative BCVA refers to BCVA measured at the patient’s last visit. Anatomical success was defined as persistent complete reattachment of the retina and macula for more than 6 months after silicone oil removal.
The presence of PVR was primarily confirmed using retinal drawings and medical records written during the initial RRD surgery and silicone oil removal. If PVR was not documented, an ultra-widefield fundus image taken before surgery was reviewed to include definitively identifiable PVR ≥grade B on the fundus image. In the absence of recurrent RD, the eye was monitored for incident PVR for up to 3 months after silicone oil removal, because 95% of postoperative PVR is known to occur within the first 45 days after surgery [22].
Surgical technique
Surgery was performed by experienced retinal specialists at a high-volume referral-based tertiary hospital. The standard three-port pars plana vitrectomy was performed using the Constellation 23- or 25-gauge surgical vitrectomy system (Alcon Laboratories Inc) according to the surgeon’s preference. The decision to remove silicone oil, which was at the discretion of each surgeon, was primarily based on the presence and grade of PVR, history of silicone oil exchange, and potential for vision recovery. During silicone oil removal, endolaser treatment was performed in cases of residual partial detachment requiring additional laser photocoagulation, newly discovered lattice degeneration, or retinal holes, and for prophylaxis against recurrent retinal detachment. Tamponade using 22% sulfur hexafluoride (SF6) or 14% perfluoropropane (C3F8) gas after silicone oil removal was performed at the discretion of the attending surgeon based on patient factors. Concomitant surgical procedures performed during the primary operation or silicone oil removal were determined by each surgeon according to the presence and grade of PVR, extent of RD, location and number of retinal breaks, and lens status.
Statistical analysis
Statistical analysis was performed using the IBM SPSS ver. 26.0 (IBM Corp). The Mann-Whitney U-test, chisquare test, and Fisher exact test were used in the univariate analysis to determine associations between demographics, duration of silicone oil tamponade, concomitant surgical procedure during the primary operation or silicone oil removal, BCVA, and recurrent RD. Logistic regression was used to determine the predictive factors for favorable visual or anatomical outcomes. Identified prognostic factors for recurrent RD after silicone oil removal from previous studies were used as variables in the logistic regression model for recurrent retinal detachment after silicone oil removal. Statistical significance was set at p < 0.05.
Results
A total of 147 eyes met the inclusion and exclusion criteria. The mean ± standard deviation age of all patients was 49.7 ± 16.2 years with 49 (33.3%) being female. PVR at the time of initial RRD repair was documented in 56 eyes (38.1%). Eyes without PVR received silicone oil injection because of the surgeon’s or patient’s preference over gas injection. A long axial length was observed in 53 eyes (36.1%). The macula was detached before RRD repair with silicone oil tamponade in 107 eyes (72.8%). RD extension >2 quadrants before surgical repair was observed in 81 eyes (55.1%). Scleral encircling or buckling during the initial RRD repair was performed in 83 eyes (56.5%) and retinectomy during the initial RRD repair was performed in 36 eyes (24.5%). Endolaser photocoagulation and phacoemulsification with intraocular lens implantation or secondary intraocular lens implantation during silicone oil removal were performed in 30 eyes (20.4%) and 21 eyes (14.3%), respectively. The majority of eyes (128 eyes, 87.1%) did not undergo gas tamponade during silicone oil removal. Silicone oil was removed after a mean tamponade of 4.7 ± 5.01 months (range, 1–38 months). Anatomical success was achieved in 124 eyes (84.4%) after silicone oil removal. The mean preoperative logMAR BCVA was 0.99 ± 0.54 and postoperative logMAR BCVA was 0.59 ± 0.60.
Except for age, previous silicone oil exchange, and BCVA before silicone oil removal, baseline characteristics were not significantly different between the short-term silicone oil tamponade group (tamponade duration, ≤3 months) and long-term silicone oil tamponade group (tamponade duration, >3 months) (Table 1). The mean age in the short- and long-term tamponade groups was 52 ± 14.5 and 46.7 ± 17.4 years, respectively. The preoperative log-MAR BCVA in the short- and long-term tamponade groups was 0.867 ± 0.563 and 1.190 ± 0.562, respectively. Treatment factors were not significantly different between the short- and long-term tamponade groups (Table 2). BCVA measured before and after silicone oil tamponade was significantly worse in the long-term tamponade group than in the short-term tamponade group. However, univariate analysis revealed no significant differences in the ratio of BCVA improvement after silicone oil removal between the two groups.
Baseline characteristics
Treatment factors and outcomes
Univariate analysis
The univariate analysis results are summarized in Table 3. Improved BCVA after silicone oil removal (p = 0.001) was associated with a decreased rate of recurrent RD after silicone oil removal. Demographics, preoperative ocular characteristics, concomitant procedures during the primary operation or silicone oil removal, duration of silicone oil tamponade, and gas tamponade after silicone oil removal were not associated with anatomical success after silicone oil removal.
Comparison between success and failure after SOR
Results of the univariate analysis of intraoperative and postoperative factors related to concomitant endolaser photocoagulation during silicone oil removal is presented in Table 4. PVR occurring within 3 months after silicone oil removal (p < 0.001) and localized focal detachment at the time of silicone oil removal (p < 0.001) were associated with a higher rate of concomitant endolaser photocoagulation during silicone oil removal, while residual detachment immediately after silicone oil removal was not significantly associated.
Intraoperative and postoperative factors related to endolaser during SOR
Results of the subgroup analysis of endolaser photocoagulation during silicone oil removal are presented in Table 5. Partial detachment at the time of silicone oil removal, PVR at the time of silicone oil removal, reinforcement of barrier or prophylactic 360° endolaser photocoagulation, and PVR occurring within three months after silicone oil removal were not associated with anatomical success after silicone oil removal.
Subgroup analysis of endolaser application during SOR
Multivariate analysis
A summary of the logistic regression model for recurrent retinal detachment after silicone oil removal is presented in Table 6. Concomitant endolaser photocoagulation during silicone oil removal (odds ratio [OR], 0.309; 95% confidence interval [CI], 0.106–0.898; p = 0.031) was associated with a lower rate of anatomic success after silicone oil removal. Axial length, previous scleral encircling or buckling, previous silicone oil exchange, and duration of silicone oil tamponade were not significantly associated with the rate of anatomical success.
Logistic regression model summary for retinal redetachment after SOR
The logistic regression model for changes in BCVA after silicone oil removal is shown in Table 7. The duration of silicone oil tamponade (OR, 1.226; 95% CI, 1.073–1.402; p = 0.003), and recurrent RD after silicone oil removal (OR, 3.400; 95% CI, 1.311–8.817; p = 0.012) were associated with a higher rate of lack of improvement in BCVA after silicone oil removal. Preoperative macula-off status was not significantly associated with the rate of change in BCVA after silicone oil removal.
Logistic regression model summary for change in BCVA (logMAR) after SOR
Discussion
In this study, we evaluated the factors affecting recurrent RD and final visual acuity after silicone oil removal in patients with RRD treated with silicone oil tamponade for >1 month. No identifiable preoperative or intraoperative factors significantly affected the recurrent RD rate, except for endolaser photocoagulation during silicone oil removal. The duration of silicone oil tamponade, history of scleral encircling, and history of silicone oil exchange were not associated with recurrent RD rates. Furthermore, recurrent RD after silicone oil removal and a prolonged duration of silicone oil tamponade were associated with a decline in visual acuity after the removal. The recurrent RD rate after silicone oil removal in patients with previous RRD was 15.6%. The recurrent RD rate was comparable to those of previous studies, including a silicone study (14%) [23] and other studies (ranging from 9% to 28%) [8,10–12,24,25].
Consensus on the optimal duration of silicone oil tamponade is lacking. Although chorioretinal adhesion typically forms within 1 month, silicone oil is frequently maintained for an extended duration with the expectation of mitigating traction induced by proliferation and reducing the proliferation itself. Some studies support this concept, demonstrating a higher attachment rate in the group with prolonged silicone oil tamponade [12]. In contrast, other studies have reported that the tamponade duration is not associated with the recurrent RD rate [10,14,15]. However, prolonged retention may increase the risk of silicone oil–related complications [16]. Our study showed that the duration of the silicon oil tamponade was not associated with anatomical success after silicone oil removal. Eyes with a longer silicone oil tamponade duration had worse visual acuity at the final postoperative visit. This may be attributed to the decision to prolong the retention of silicone oil in eyes with more severe PVR or limited visual potential to mitigate the progression of PVR. However, the risk of complications associated with silicone oil that might impact visual acuity is lesser in these conditions. Even after adjusting for the worse preoperative visual acuity in the longer tamponade group, a longer duration of silicone oil tamponade was significantly associated with a lower rate of visual acuity improvement. Silicone oil may induce retinal toxicity and intraocular inflammation; thus, visual recovery may be affected in the longer tamponade group [26–29]. Other complications following silicone oil tamponade, such as glaucoma, emulsification, keratopathy, and cataract progression, may also contribute to the worsening of visual acuity. The timing of silicone oil removal is based on the surgeon’s judgement, and the status of each patient should be considered; however, a tamponade for <3 months is recommended to prevent worsening of visual acuity when the vitreous and retina are sufficiently stabilized.
The efficacy of using argon laser during silicone oil removal as a preventive measure against subsequent recurrent RD remains indeterminate. Previous retrospective and prospective studies have shown that prophylactic 360° photocoagulation reduces the risk of recurrent RD after silicone oil removal [6–9]. However, conflicting reports exist, with some studies suggesting that argon laser applied during silicone oil removal is not associated with the recurrent RD rate [10,12]. In our study, argon endolaser photocoagulation during silicone oil removal, including both prophylactic 360° laser and endolaser reinforcement of previous laser bridging, was associated with an increased rate of recurrent RD. Postoperative PVR and residual focal localized retinal detachment at the time of silicone oil removal were associated with an increased rate of argon endolaser application during silicone oil removal. However, these factors, along with PVR during silicone oil removal, were not associated with a higher rate of recurrent RD in the subgroup of cases where endolaser was applied during silicone oil removal. Reinforcement or prophylactic laser application was not significantly associated with recurrent RD in this subgroup; however, a tendency towards a decreased rate of recurrent RD after silicone oil removal was observed (p = 0.099). This suggests that endolaser photocoagulation itself may not increase the rate of RD. Conditions requiring endolaser during silicone oil removal, such as incomplete chorioretinal adhesion or newly formed retinal holes, might increase the recurrent RD rate. However, this relationship is not clearly proven by our data, and further research with a larger number of patients is warranted.
Previous studies have suggested that prophylactic scleral buckling in silicone tamponade–treated eyes prevents recurrent RD following silicone oil removal. Jonas et al. [11] and Nagpal et al. [13] reported that buckling is a protective preoperative factor against recurrent RD after oil removal. However, other studies have reported that preexisting scleral buckling at the time of silicone oil removal is not associated with a reduced rate of recurrent RD after silicone oil removal [10,12]. Similarly, in our study, scleral buckling or encircling performed before silicone oil removal did not act as protective preoperative factors against recurrent RD after oil removal.
This was a retrospective study with limitations inherent to its design. Despite including all RRD cases with silicone oil tamponade that met the inclusion and exclusion criteria during the study period, the lack of patient randomization is a notable limitation. We included a total of 147 eyes in total, which was consistent with that of previous studies on recurrent RD after silicone oil removal. Nonetheless, the results should be interpreted with caution owing to the relatively small sample size. Additionally, vitrectomies were performed by several surgeons. This study could not include the grade of PVR as a parameter because PVR was not graded in most medical records, and grading PVR through fundus images can be inaccurate. Lastly, the final BCVA after the removal of silicone oil was measured at the patient’s most recent visit, which differed among patients, limiting the interpretation of visual activity outcomes.
In conclusion, the duration of silicone oil tamponade was not significantly associated with the recurrent RD rate after silicone oil removal in eyes with RRD. In addition, previous scleral buckling or encircling and a history of silicone oil exchange were not significantly associated with the recurrent RD rate. However, prophylactic laser retinopexy at the time of silicone oil removal was associated with a higher recurrent RD rate. Eyes with a longer duration of silicone oil tamponade duration had worse visual outcomes and lower rates of visual improvement after silicone oil removal. Uncertainty persists regarding whether these outcomes arose from the intentional extension of silicone oil retention in patients with a reduced probability of visual enhancement or resulted from retinal toxicity and complications associated with silicone oil tamponade.
Acknowledgements
None.
Notes
Conflicts of Interest: None.
Funding: This study was supported by an academic grant (No. HI22C0706, awarded to HGK) from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Korean Ministry of Health and Welfare; a Young Medical Scientist Research Grant (No. 2022-31-1372, awarded to HGK) through the Seokchun Nanum Foundation (Yongin, Korea); and the Faculty Research Grant Assistance Program of Yonsei University College of Medicine (No. 6-2023-0128, awarded to HGK). The funding organizations had no role in the study design, data collection, analysis, interpretation, or writing of the manuscript.