|Year : 2021 | Volume
| Issue : 3 | Page : 149-152
Complications associated with the use of two types of silicone oil in vitreoretinal surgeries: A single tertiary center experience in Oman
Mohamed Al-Abri1, Ahmed Al-Hinai1, Adil Al-Musalami2, Huda Al-Ghaithi2
1 Department of Ophthalmology, Sultan Qaboos University Hospital, Seeb, Oman
2 Ophthalmology Residency Training Program, OMSB, Muscat, Oman
|Date of Submission||19-May-2021|
|Date of Decision||05-Jul-2021|
|Date of Acceptance||05-Jul-2021|
|Date of Web Publication||20-Oct-2021|
Dr. Mohamed Al-Abri
Department of Ophthalmology, Sultan Qaboos University Hospital, P. O. Box 38 Al-Khod, P C 123, Muscat
Source of Support: None, Conflict of Interest: None
| Abstract|| |
OBJECTIVES: The objective of this study is to describe complications associated with the use of two types of silicone oil (SO) (1000 centistokes [cs] and 5000 cs) in vitreoretinal surgery in Oman.
MATERIALS AND METHODS: This is a retrospective descriptive study on all patients who underwent vitreoretinal surgeries in which SO injection or removal was done. The study was conducted at Sultan Qaboos University Hospital between January 1, 2010, and December 31, 2017. Demographic data, lens status of the eye at the time of SO injection, type of SO used (1000 cs or 5000 cs), and complications associated with SO were collected.
RESULTS: A total of 107 eyes of 103 patients were included in the study. SO 1000 cs was used in 66 eyes and SO 5000 cs was used in 41 eyes. A total of 29 eyes (27%) developed SO-related complications, which included SO emulsification in 14 eyes (13.1%), raised intraocular pressure (IOP) >21 mmHg in 19 eyes (17.8%), and band keratopathy in 4 eyes (3.7%). SO emulsification was seen in eight eyes (12.1%) in whom SO 1000 cs was used and in five eyes (12.2%) in whom SO 5000 cs (P = 1.000).
CONCLUSION: SO was found to be a relatively safe adjunct in vitreoretinal surgery. SO-related complications such as SO emulsification, raised IOP, and band keratopathy were observed in less than one-third of study eyes. No difference was noted in emulsification rate between SO 1000 cs and SO 5000 cs. Further studies with larger sample size and longer follow-up period are warranted.
Keywords: Cataract, complications, emulsification, endotamponade, glaucoma, keratopathy, silicone oil
|How to cite this article:|
Al-Abri M, Al-Hinai A, Al-Musalami A, Al-Ghaithi H. Complications associated with the use of two types of silicone oil in vitreoretinal surgeries: A single tertiary center experience in Oman. Oman J Ophthalmol 2021;14:149-52
|How to cite this URL:|
Al-Abri M, Al-Hinai A, Al-Musalami A, Al-Ghaithi H. Complications associated with the use of two types of silicone oil in vitreoretinal surgeries: A single tertiary center experience in Oman. Oman J Ophthalmol [serial online] 2021 [cited 2021 Nov 27];14:149-52. Available from: https://www.ojoonline.org/text.asp?2021/14/3/149/328600
| Introduction|| |
Silicone oil (SO) is a commonly used vitreous substitute and endotamponade in the repair of complex retinal detachments (RDs) and other retina conditions. It was first reported for the treatment of RD in 1962. There are two main types of SO; lighter-than-water SO, which is the most commonly used, and heavier-than-water SO (heavy SO). Conventional lighter-than-water SO includes 1000 cs SO and 5000 cs SO.
Reported SO-related complications are SO emulsification (0.7%), raised intraocular pressure (IOP) >21 mmHg (6%), band keratopathy (5.5%), and cataract formation.
Like other parts of the world, SO is being used locally for various indications in vitreoretinal service in Oman. This study was conducted to describe the complications associated with the use of 1000 cs and 5000 cs SO in vitreoretinal service in Oman. To the best of our knowledge, there are no previously reported similar studies from Oman. We believe that this work provides some data related to the use of SO in Oman and opens the door for similar studies in the future.
| Materials and Methods|| |
This is a retrospective descriptive study on all patients who underwent vitreoretinal surgery in which SO injection or removal was done. The study was conducted at Sultan Qaboos University Hospital between January 1, 2010, and December 31, 2017. The ethical approval was obtained from the institutional research and ethics committee. Patients with <6 months of follow-up and those with missing data were excluded from the study. Demographic data, status of the eye at the time of SO (i.e., phakic, pseudophakic, or aphakic), type of SO used (1000 cs or 5000 cs), and complications associated with SO were extracted from the patients' electronic medical records. Descriptive statistical analysis and Chi-square test were used for data analysis.
| Results|| |
A total of 107 eyes of 103 patients were included in the study. The median age of the patients was 57 years (range: 43–63). Sixty-five (63%) patients were males and 38 (37%) were females. With respect to lens status at the time of SO injection, 34 eyes (31.8%) were phakic, 61 eyes (57%) were psudophakic, and 12 eyes (11.2%) were aphakic [Figure 1]. In the studied eyes, 1000 cs SO was used in 66 eyes (62%) and 5000 cs SO was used in 41 eyes (38%). The recorded indications for using SO in this study were RD in 85 eyes (79%); out of these, 20 eyes (23.5%) were diabetic tractional RD (TRD) and 8 eyes (9.4%) were macula hole RD. Other recorded indication was vitreous hemorrhage in 22 eyes (21%). A total of 29 eyes (27%) developed SO-related complications, which included SO emulsification in 14 eyes (13.1%), raised IOP (>21 mmHg) in 19 eyes (17.8%), and band keratopathy in four eyes (3.7%) [Figure 2]. SO emulsification was seen in eight eyes (12.1%) in whom 1000 cs SO was used and in five eyes (12.2%) in whom 5000 cs SO (P = 1.000) [Figure 3]. Overall, the rate of SO emulsification was noted to be higher in aphakic and pseudophakic (25% and 16.7%, respectively) compared to phakic eyes (2.9%). Finally, the raised IOP was found to be statistically not significant among the two types of SO (57.9% in 1000 cs and 42.1% in 5000 cs, P = 0.215) [Figure 4].
|Figure 3: Rate of silicone oil emulsification in silicone oil 1000 cs and 5000 cs|
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|Figure 4: Rate of raised intraocular pressure (>21 mmHg) in silicone oil 1000 cs and 5000 cs|
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| Discussion|| |
SO has been used as vitreous substitute and endotamponade in complex RD surgeries and other retina conditions for over four decades. Its use in ophthalmology as a vitreous substitute started in the early 1960s, and this is a shorter history compared to the use of intraocular gases. Its use in complex RD has led to favorable outcomes. The indications for SO endotamponade are divided into eye-related (e.g. proliferative vitreoretinopathy, ocular trauma, TRD secondary to proliferative diabetic retinopathy and vein occlusions, RD with coloboma) and patient-related (e.g., postoperative positioning concerns [e.g., in children and mentally incompetent patients] and the need to be high altitude or air traveling). When it is injected into the vitreous cavity, it requires subsequent removal few months later depending on the nature of the indication and any SO-related complications that may be observed during the follow-up period. However, removal of SO may cause reproliferation of epiretinal membranes leading to recurrent detachment. Therefore, periodical monitoring after SO removal is recommended.
SO-related complications such as oil emulsification, raised IOP, band keratopathy, and cataract are known and should be addressed before surgery and monitored during follow-up visits.
SO emulsification is a common challenging condition when it occurs. Usually, it is more frequent when low-viscosity SO is used compared to high-viscosity oil., One theory behind that is the free movement of the oil inside the eye. The more the movement, the more the risk of emulsification. Hence, complete filling of the vitreous cavity with SO may minimize the emulsification risk by reducing oil movement. It was noticed that when a high molecular weight substance is added to the low-viscosity SO, the risk of emulsification is reduced. In our cohort of patients, there was no significant difference in the rate of emulsification between both types of the used SO. This could be true and might be attributed to modified formula of the new SO, or the results might be attributed to cofactors such as low sample size between both groups and duration of SO remained inside the eye. Similar rate of oil emulsification in both SO types was found in another study. In our clinical observation, phakic eyes seem to have less tendency of having oil emulsification compared to aphakic and pseudophakic eyes. This could be explained by the disturbance of the natural barrier between anterior chamber and vitreous cavity in aphakic and pseudophakic eyes. Moreover, the natural lens blocks the passage of SO to the anterior chamber and therefore less SO movement and theoretically less risk of oil emulsification. In our study, the aphakic and pseudophakic eyes in this study were almost two-third of the total sample included (68.2% compared to 31.8% of phakic eyes), which might be contributed to the oil emulsification observed in study eyes.
Another reported complication related to the use of intraocular SO is the raised IOP. Its incidence has been reported between 2.2% and 56%. There are several mechanisms for the IOP to rise after SO injection. This includes oil emulsification, inflammation, oil migration into anterior chamber, and pupillary block mechanism., Some patients are more at risk to develop secondary glaucoma. Important risk factors contributing to raised IOP are aphakia, preexisting glaucoma, long duration of SO remained in the eye, diabetic retinopathy, and neovascular glaucoma. In our study, the raised IOP was higher among the aphakic and pseudophakic eyes (33.3% and 20%, respectively) compared to phakic eyes (8.8%), and again, this could be attributed to the disruption in the natural lens barrier.
Keratopathy might develop after SO use. Its incidence has been reported up to 27% within 2 years. It occurs when SO is in contact with the corneal endothelial surface. The risk is increased in aphakic eyes. The pathogenesis of SO-induced keratopathy has been described, which includes retrocorneal membrane formation, stromal hypercellularity, superficial stromal calcification and vascularization, decreased endothelial cell density, and attenuation of endothelial cell borders leading to bullous keratopathy. We recorded rate of 3.7% of band keratopathy as a complication from SO in this study.
Overall, this study has reported known complications related to SO and has eluded to possible risk factors. However, we believe there are other factors that might had contributed in those complications, e.g. the duration of SO remained inside the eyes and others which could not be assed due to missing data.
This study has limitations similar to those inherent in most of retrospective studies, including missing data resulted in relatively small sample size, and hence, this might hinder important results, and therefore, comparison between the two types of the SO might not be very accurate. Therefore, well-designed prospective, multicenter study with more sample size may leads to more accurate results.
| Conclusion|| |
SO was found to be relatively safe adjunct in vitreoretinal surgery. SO-related complications such as SO emulsification, raised IOP, and band keratopathy were observed in less than one-third of the study eyes. No difference was noted in emulsification rate between SO 1000 cs and SO 5000 cs. Further, studies with larger sample size and longer follow-up period are warranted.
We would like to thank the following colleagues:
- Mr. Sathiya Murthi Panchatcharam, Statistics Specialist, Research Section, OMSB, for assisting in data analysis
- Ms. Zuweina Al Rahbi, Staff Nurse, Sultan Qaboos University Hospital, for facilitating data collection.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]