|Year : 2015 | Volume
| Issue : 2 | Page : 39-44
Early versus late silicone oil removal after pars plana vitrectomy for rhegmatogenous retinal detachment in Upper Egypt
Ahmed M Fathalla, Tarek A Mohamed, Dalia M Al-Sebaity
Department of Ophthalmology, Assiut University Hospital, Assiut, Egypt
|Date of Web Publication||7-Nov-2016|
Ahmed M Fathalla
Department of Ophthalmology, Assiut University Hospital, Assiut
Source of Support: None, Conflict of Interest: None
Objective: To compare the results of silicone oil removal (SOR) 2 months after vitrectomy for retinal detachment with delayed removal for 6 months or more. Study: Prospective and retrospective study. Patients and Methods: A total of 32 patients (32 eyes) in the prospective series of early SOR and 19 patients (22 eyes) in the retrospective series of late removal. The two groups were compared as to the condition of the eye at the time of SOR and 6 months following SOR. Results: Patient compliance with the scheduled time for SOR was more in the early removal series. The outcome was comparable in the two groups as to the risk of retinal re-detachment, while cataract, increased intraocular pressure, oil emulsification, keratopathy, and anterior segment inflammation were more frequently encountered at the time of removal in the late removal series, particularly when it was delayed beyond 6 months. Conclusion: A protocol of early removal of silicone oil after 2 months did not increase the risk of re-detachment, and ensured a better compliance of the time of removal. It can be particularly recommended when patients are less likely to comply with a protocol for delayed removal.
Keywords: Retinal detachment, silicone oil removal, vitrectomy
|How to cite this article:|
Fathalla AM, Mohamed TA, Al-Sebaity DM. Early versus late silicone oil removal after pars plana vitrectomy for rhegmatogenous retinal detachment in Upper Egypt. Egypt Retina J 2015;3:39-44
|How to cite this URL:|
Fathalla AM, Mohamed TA, Al-Sebaity DM. Early versus late silicone oil removal after pars plana vitrectomy for rhegmatogenous retinal detachment in Upper Egypt. Egypt Retina J [serial online] 2015 [cited 2021 Jun 21];3:39-44. Available from: https://www.egyptretinaj.com/text.asp?2015/3/2/39/193468
| Introduction|| |
Combined with vitreoretinal surgery, silicone oil injection has become a standard technique to improve the prognosis of complex retinal detachment associated with proliferative vitreoretinopathy (PVR), giant retinal tears, proliferative diabetic retinopathy, or ocular trauma. , Compared with sulfur hexafluoride gas as an intraocular tamponade for the management of retinal detachment, eyes treated with silicone oil were more likely to be successfully re-attached, to achieve a better visual acuity and to have fewer postoperative complications. , Unlike intraocular gas, silicone oil is a liquid polymer with no expansile property, and it is not absorbed. It is immiscible in water and perfluorocarbon liquid and creates a readily visible meniscus during intraoperative use. Although silicone oil's viscosity is greater than that of gas, its buoyancy and surface tension are less than that of intraocular gas, and therefore, it exerts less retinal tamponade. 
Silicone oil provides internal tamponade, stabilization and fixing of the retina after vitrectomy. However, silicone oil, if left for a long time, may lead to long-term complications particularly cataract, glaucoma, and keratopathy. Hence, silicone oil removal (SOR) is advocated as soon as a stable retinal situation is achieved.  Silicone oil should remain in situ until a stable anatomical and functional status has been achieved and presumably the proliferative process has stopped. Such a stable situation is somewhat difficult to assess and is largely based on clinical appearances and surgeon experience. The timing for SOR is still controversial. It is difficult to fix the right time for its removal since there are no certain parameters that might indicate when the proliferation process has ended. 
In our practice, we used to adopt a protocol for SOR after 6 months. We noticed that many of our patients, mostly a rural population, did not comply with this protocol and only reported for oil removal after much longer periods, commonly when they develop a severe headache because of raised intraocular pressure (IOP), diminished visual acuity or noticing something white inside the eye due to emulsified silicone in the anterior chamber. In this study, we present the results of early (after 2 months) SOR, compared with delayed removal, regarding patient compliance, ocular complications of silicone oil and risk of retinal re-detachment.
| Patients and Methods|| |
The early removal series was a prospective one that included 32 patients (32 eyes), 23 patients were males and nine were females. The average age of patients was 43 years (range 35-66) year. All the patients were enrolled in this study after their informed consent.
The late removal series was a retrospective one that included 19 patients (22 eyes). Thirteen patients were males and six were females. The average age of patients was 34 years (range 13-55 years).
Most of the patients came from the rural areas served by our hospital and practice. The two procedures for each patient of the two series were carried out by one surgeon.
Patients had successful 3-port pars plana vitrectomy with silicone oil tamponade in Assiut University Hospital and private practice from January 2012 to March 2013 in the early removal series and between March 2010 and November 2011 in the late removal series. PVR was graded according to the updated PVR grade classification (1991). 
Grading of the PVR in the two series is shown in [Table 1].
Patients were instructed to come back for SOR after 2 and 6 months in the early and late removal series, respectively.
All patients underwent complete preoperative ocular examination including assessment of uncorrected and best-corrected visual acuity, measurement of IOP using applanation tonometer, slit lamp examination with particular attention to the status of cornea and lens, and binocular indirect ophthalmoscopy with particular attention to the grade of PVR.
Silicone oil was removed by the oil-fluid exchange. An inferior temporal sclerotomy was done for the infusion cannula. Oil was removed using active aspiration cannula through a second sclerotomy. After oil removal, endoillumination was used to assess the condition of the retina. In cases where cataract extraction was needed, phacoemulsification with intraocular lens implantation was done first, followed by oil removal as described above.
Postoperative topical antibiotics, cycloplegics, and corticosteroid were used in a standard fashion and tapered accordingly over 4-6 week.
Complete ocular examinations including indirect ophthalmoscopy were carried out at 1 day, 1 week, 1 month, and 3 and 6 months postoperatively. We followed the patients after for evidence of recurrent retinal detachment and other complications related to the silicone oil, including persistent IOP elevation, cataract formation, and corneal decompensation.
Statistical analysis was performed using SPSS version 17 for windows (IBM analytica is the manufacturer company). Data were summarized as percentages. Statistical significance of the difference between early and late removal groups was performed using Chi-square test. The value of P < 0.005 was considered statistically significant.
| Results|| |
Timing of silicone oil removal
All patients in the early removal series reported for removal around the scheduled date of 2 months. In the late removal series, although patients were instructed to come back after 6 months, only 8 patients (9 eyes) presented at 6 months, whereas 4 patients presented between 6 and 12 months, 3 patients presented between 12 and 18 months, 2 patients (3 eyes) presented between 18 and 24 months, and 2 patients (3 eyes) presented after 2 years. One patient presented at 6 months by one eye and at 20 months with his other eye. Another patient presented at 6 months with one eye and at 30 months with his other eye.
Ocular condition before silicone oil removal
Ocular condition before SOR in the two series is shown in [Table 2]. In the early removal series, cases with evidence of elevated IOP were controlled by IOP-lowering drugs. In the late series, the 12 eyes with evidence of elevated IOP did not respond to anti-glaucoma medications, and five eyes presented with glaucomatous optic atrophy [Figure 1].
|Figure 1: Glaucomatous optic atrophy in one of the patients in series of late silicone oil removal|
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In the late series, the single case presented with peripheral inferior retinal detachment in the first postoperative week. Barrier argon laser was done 2 weeks after pars plana vitrectomy. The extent of detachment remained stable after SOR.
Of the 9 eyes with oil emulsification in the late series, inverted hypopyon was noted in 6 eyes and was the presenting symptom in 2 patients as they noticed something white inside their eyes.
In the late series, four eyes ended with visual acuity of perception of light and good projection.
The relation of ocular complication to the time of SOR is shown in [Table 3]. As shown in [Table 3], the occurrence of complications increased with the duration of delay before SOR. When removal was delayed to more than 12 months, 27 complications were recorded in the 9 eyes.
|Table 3: Ocular complications in relation to the time before oil removal in the late removal series|
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Findings on follow-up
Complications at follow-up in the two series are shown in [Table 4].
In the early series, elevation of IOP occurred during the first postoperative month in 4 eyes. Three cases were early controlled by standard IOP-lowering drugs, one eye showed the persistent elevation of IOP until controlled medically by the third postoperative month. No eye required surgical intervention to control the IOP. None of these eyes showed irreversible optic nerve damage.
In the late series, elevation of IOP was observed in 14 eyes. Anti-glaucoma drugs were needed to control the IOP in 5 eyes. Transscleral cyclophotocoagulation was needed in 3 eyes. Ahmed valve was done in 2 eyes [Figure 2]. Trabeculectomy with mitomycin was done in 4 eyes and failed in 3 eyes.
|Figure 2: Ahmed valve in one of the patients in series of late silicone oil removal|
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In the late series, persistent corneal edema was noted 2 days after SOR. The patient was aphakic with silicone oil filling the anterior chamber, although the cornea was clear before surgery. The patient, in this case, came for SOR after 18 months [Figure 3].
|Figure 3: Persistent corneal edema noted 2 days after silicone oil removal in one of the patients in series of late silicone oil removal|
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| Discussion|| |
The timing for SOR is still controversial and varies in reported series, from 8 weeks to 6 months ,, in some series, to 6 and 22 months in other series. 
Our results, based on a prospective and a retrospective series showed no difference in retinal re-detachment between early removal of silicone oil (ROSO) (after 2 months) and delayed removal (up to 6 months), over a period of follow-up of at least 6 months. Re-detachment of the retina occurred in 2 eyes (out of 32) in the early removal series and in 3 eyes (out of 22) in the delayed removal series. However, planned the early ROSO 2 months from the first surgery helped in patients' compliance with the scheduled time for SOR and consequently minimizing silicon oil-related complications. The planned prolonged time (6 months) of a second surgery may make some patients, particularly in our rural community, more reluctant in returning at the proper time as long as they have no visual complaints and feel they are fine. Serious irreversible blinding complications occurred with prolonged time of silicone oil inside the eye. Elevated IOP was the main serious complication of delayed ROSO, causing an irreversible visual loss at the time of presentation in some cases. Other cases needed destructive and sophisticated surgeries or multiple anti-glaucoma medications to control their IOP. Some of these eyes did not respond to either surgery or medical treatment, and visual loss progressed. Other complications could be controlled either surgically as cataract or medically as anterior segment inflammation. There was no direct and constant correlation between prolonged delay of SOR and occurrence of complications. Some eyes with prolonged SOR remained without any complications. Some eyes (2%) showed early emulsification while others (60%) retained their oil unemulsified and without ocular complications despite prolonged time of oil inside the eye.
In our series, we report an incidence of recurrent retinal detachment of 6% in the early removal series and 13% in the late removal series. The rate of recurrent retinal detachment in previous reports has varied from <1% to over 50%. ,
The time for recurrent retinal detachment after SOR varied in reported series. It was reported to occur within 6 months of the procedure and often within 3 months.  Another report evaluated the timing of retinal re-detachment after ROSO and found that the greatest risk of re-detachment was within 50 days of oil removal with the risk decreasing sharply after 3-5 months.  The short period of time between ROSO and recurrent detachment would implicate either residual anterior retinal traction or opening of old breaks that had been tamponaded by the silicone oil or, possibly new breaks from intraocular manipulation. An important factor in the development of retinal re-detachment is the continuing traction exerted by epiretinal membranes present in PVR.
In our series, the 5 eyes in the early and late series which developed retinal re-detachment were having PVR grade (C).
A recent report investigated factors that may have implications on retinal re-detachment after SOR, including encircling band, 360 laser retinopexy, emulsified oil and duration of silicone oil.  They reported that the duration of tamponade does not have a major role in the prevention of retinal re-detachment. They concluded that no definite guidelines in SOR which can lead to less incidence of re-detachment.
Another study reported re-detachment rates of 13% with PVR following silicone oil tamponade of 6-8 weeks.  Re-detachment rates ranged from 34% to 0% when the oil remained in the eye for 5.5-6 months. There seems to be no clear evidence for a reduction in the rate of re-detachment after extended oil tamponade. High incidence of re-detachment following SOR in some series was probably due to the inclusion of cases with giant retinal tears, which were excluded in this study.
In our series, we reported cataract formation in 2 eyes 6% in the early removal series and 14 eyes 63.6% in the late removal series. Patients underwent cataract extraction at the time of SOR.
Other studies have also reported a significant incidence of cataract formation.  One study reported that 43% of their patients had a cataract at the time of SOR.  Another study correlated changes in the lens in 3 groups of patients who had SOR at variable times.  In the group of patients who kept the silicone oil in the eye for3 months, the lens opacification was found in 30% of patients. In the second group, with silicone kept up to 6 months, 62.5% of patients had lens opacification. In the third group who had silicone up to 9 months, the lens opacification progression was found in 100% of patients. The results indicated that early SOR had a significant effect in lowering progression and lens opacification due to silicone oil.
The lens changes appeared to be due to deposition of silicone laden macrophages on the surface of the lens capsule preventing normal metabolic exchange.  So, the longer the oil remained in the eye, the greater the risk of progressive lens opacities. 
In our series, we reported an incidence of 18.7% of IOP elevation in the early removal and 63.6% in the late removal series. Nine eyes (41%) had persistent high IOP till the end of follow-up period following medical and surgical treatment. In a previous study,  18% of patients had chronic elevated IOP following SOR.
The reason of elevated IOP with the use of silicone oil as a tamponade after pars plana vitrectomy is multifactorial, including inflammation, previous vitreoretinal procedures, and overfilling. 
Oil emulsification is a major factor in IOP elevation after vitrectomy. Several factors help in the acceleration of oil emulsification including the presence of red blood cell membranes, plasma lipoproteins, and the oil aqueous movement caused by high-speed vitrectomy handpieces resulting in shearing forces. 
In some cases, the IOP increased after SOR. This could be due to emulsification inducing chronic reaction. The reaction of macrophages towards the emulsified silicone may theoretically cause IOP rise. 
The persistence of IOP rise after SOR could be due to the presence of emulsified silicone obstructing the trabecular meshwork. 
Silicone oil-induced IOP elevation can occur in phakic as well as aphakic eyes. This could be explained by the release of fine particles of silicone oil in anterior chamber and silicone oil laden macrophages which have migrated forward from the bubble present in the posterior segment causing obstruction of the trabecular meshwork. 
The exact causes of silicone oil-induced IOP elevation and its relation to the timing of removal need further in-depth study possibly including histopathological examination of the trabecular meshwork in patients undergoing anti-glaucoma surgeries. This will be especially beneficial for patients with obviously undetected silicone oil emulsification and cases with labile IOP elevation.
Band keratopathy was not observed in any of our patients in the early removal series, occurred in 2 eyes in the form of band keratopathy in the late removal series and persisted after SOR. Keratopathy was reported in 25% of patients in the silicone oil study group.  In one aphakic eye in our series, corneal decompensation occurred 2 days after SOR. The cornea in this eye was clear before surgery. This also was reported and explained by complete filling of the AC by silicone oil with the cornea appear clear although severe endothelial cell loss coexists. 
Oil emulsication was reported to increase the incidence of retinal re-detachment after SOR.  We did not find such correlation in our series. This may be explained by the huge number of eyes in the reported study (412 eyes) compared to the relatively small number of eyes in our series.
Other complications as expulsive hemorrhage or choroidal detachment were not observed in the two series.
In our series, we did not rely on the improvement of visual acuity as a factor in considering early ROSO, as it is affected by multiple factors.
Limitations of the study
The study lacks the strength of a randomized controlled trial. The number of cases is not large enough to make statistically significant conclusions. Future studies may address these shortcomings.
Implications of the findings
Leaving silicone oil inside the eye for more than 2 months was not associated with additional long-term benefit in our cases. The only benefit is to keep the patient's retina attached until the time of SOR. If there is lower PVR or a break supported by silicone oil, the retina will detach whenever the oil is removed.
IOP is the main issue in the timing of SOR. In many eyes, emulsification occurred too early raising the needs of early oil removal before the development of serious ocular complications.
| Conclusion|| |
The duration of silicone oil tamponade had no significant effect on the re-attachment rate in our early and late removal series. Early SOR after 2 months had the same therapeutic result as when removal was scheduled after 6 months. Patient compliance was more with early scheduled removal in our rural community. Prolonged delay before oil removal resulted in serious complications in some patients.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]