Silicone Oil Keratopathy
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Disease Entity
Silicone Oil Keratopathy (also known as Emulsified Oil Keratopathy)
Disease
- Silicone Oil Keratopathy is a condition of corneal decompensation caused by the deposition or migration of silicone oil, typically used as a vitreous substitute in retinal surgeries, onto the corneal surface or stroma. This condition may result in corneal damage, including epithelial irregularities and stromal edema that can negatively impact vision.
Etiology/Epidemiology
The etiology of silicone oil keratopathy is due to the intraocular insertion of silicon oil after surgical intervention. The incidence of SO keratopathy is 6-9.4% in recently published literature. [1], [2] Most recent reports of SO keratopathy reported an incidence in 28% of patients with silicone oil tamponade after open globe injury.[3]
Risk Factors
- Aphakic Eyes[4]
- Larger volume of silicone oil (1000ccs vs 500ccs)[5]
- Duration of tamponade[6]
- >6 months of SO tamponade[3]
- Zone III of the open globe injury[7][3]
General Pathology
The pathology of silicone oil (SO) keratopathy involves a combination of mechanical, chemical, and physiologic processes. The migration of the silicone oil into the anterior chamber can make direct impact with the corneal endothelium, which can alter its physiological function in maintaining clarity and hydration. This can indirectly affect the fluid status and reduce the oxygen content in the anterior chamber, which can increase the risk of oil emulsification. Emulsification of the silicone oil is when the separation of small SO droplets can begin to penetrate various tissues, such as the cornea. Corneal biomechanics such as corneal resistance factor (CRF) and corneal hysteresis (CH) are clinical markers that can be altered with SO in the anterior chamber.
Histology
A histopathological examination shows Descemet's membrane irregularity and thickened corneal stroma with focal intrastromal silicone oil vacuoles, surrounded by macrophages. Additional studies found retrocorneal membranes present and superficial calcification that was noted.
Pathophysiology
There is mechanical trauma when the silicone oil directly makes contact with the corneal endothelium, which is especially problematic when the patient is supine. This is more common in aphakic eyes. Weeks or months of silicon oil contact will reduce corneal endothelial counts, but usually not catastrophically.[12] Extended contact of corneal endothelium with silicone oil will cause primary endothelial failure, corneal edema, and loss of corneal clarity.
The corneal endothelium has no blood supply and derives its oxygen and glucose from the production and circulation of aqueous fluid. If the aqueous liquid is completely replaced by SO (a complete anterior chamber SO fill), then the endothelial cells can be at risk of oxygen starvation. The reduction in aqueous fluid flow across the corneal endothelium can alter the pH of the fluid and thus predispose to oil emulsification.[13]
The emulsification of silicone oil is multifactorial as it is based on the properties of the oil itself, such as interfacial tension and viscosity, as well as sheer forces from vertical and horizontal eye movements. [9] [14] Mechanical energy from intraocular surgical instruments can also increase the risk for emulsification. [15][16]
Corneal resistance factor and corneal hysteresis are two metrics used to measure the cornea's biomechanical functionality. A study compared eyes with and without tamponade. Eyes with SO tamponade showed significant decreases in corneal hysteresis (CH) and corneal resistance factor (CRF) postoperatively. The findings suggest that SO tamponade may influence corneal biomechanical properties in the early postoperative period due to surgery, tamponade, or IOP changes.[17]
Diagnosis
Diagnosis of Silicone Oil Keratopathy is primarily based on history and slit lamp examination. The etiology of SO keratopathy is specific but ruling out other causes of band keratopathy is necessary before diagnosis.
History.
Obtaining a comprehensive history is essential for diagnosing silicone oil keratopathy. This includes a detailed review of the patient’s medical history, occupational background, ocular history, and past surgical ocular history and medication use.
Physical examination
Physical exam findings in silicone oil keratopathy include decreased visual acuity (often mild) with characteristic slit lamp exam findings.
Signs
- Band keratopathy
- Corneal edema
- Corneal hypesthesia
- Endothelial opacification or “grayish-white opacities”
- Peripheral corneal vascularization
Symptoms
- Decreased visual acuity
- Foreign body sensation
- Eye irritation
- Photophobia
Diagnostic procedures
Anterior Segment OCT showing corneal thickening, intrastromal scattered hyperreflective dot, and large rounded/oval hypo-reflective space.[11]
In vivo confocal microscopy shows hyper-reflective fibrotic changes in the basal epithelium, reduced density and altered morphology of the keratocyte cell population, increased pleomorphism and polymegathism of the endothelium with reduced endothelial cells, and the presence of inflammatory cells.[11]
Management
Patients with silicone oil keratopathy are often asymptomatic and can be effectively managed through observation. Medical therapy is normally indicated for mild ocular irritation/foreign body sensation. Surgical therapy is considered after progression of the keratopathy is significantly impacting vision.
Medical therapy
Medical management of silicone oil keratopathy is similar to other forms of endothelial decompensation with bandage contact lenses and hypertonic saline drops. In settings of no or extremely poor visual prognosis, the silicone oil remains in place to counteract hypotony and phthisis. Keratopathy may be progressive, and the ocular surface needs to be monitored for secondary infection.
Surgery
Surgical intervention is considered for silicone oil keratopathy causing visual impairment or ocular surface discomfort that does not respond to conservative treatment:
- Pars plana vitrectomy removal of silicone oil[19]
- The decision to remove silicone oil must be balanced with risk of recurrent retinal detachment or hypotony.
- Manual Superficial Keratectomy[20]
- Excimer Laser Phototherapeutic Keratectomy [20]
- Penetrating Keratoplasty[21][11][22]
- Boston Keratoprothesis[23][24]
The average length of graft survival in these settings has been reported to range from 21 to 25 months. Removal of the silicone oil prior to or during the corneal transplant increases length of graft survival. [22][25][26]
Prognosis
Silicone oil keratopathy typically has a favorable prognosis. However, all of the silicone oil fragments must be removed from the cavity to prevent the induction of inflammation or corneal edema.
References
- ↑ Mazhar-ul-Hassan AK, Qidwal U, Rehman A u, Bhatti N. Assessment of the complications secondary to silicone oil injection after pars plana vitrectomy in rhegmatogenous retinal detachment in early post operative phase. Pak J Ophthalmol. 2011:27.
- ↑ Abu-Yaghi, N.E., Abu Gharbieh, Y.A., Al-Amer, A.M. et al. Characteristics, fates and complications of long-term silicone oil tamponade after pars plana vitrectomy. BMC Ophthalmol 20, 336 (2020). https://doi.org/10.1186/s12886-020-01608-5
- ↑ 3.0 3.1 3.2 3.3 He K, Liao M, Zhu Y, Cui B, Chen H, Wang T, Wu N, Xie Z, Luo J, Wei Y, Wang Z, Zhou H, Shen Z, Yan H. Risk Factors for Band Keratopathy in Aphakic Eyes With Silicone Oil Tamponade for Open-Globe Injuries: A Multicenter Case-Control Study. Front Med (Lausanne). 2021 Jul 23;8:713599. doi: 10.3389/fmed.2021.713599. PMID: 34368200; PMCID: PMC8342885.
- ↑ Balakrishna N, Channabasappa S (2020) A case of atypical band shaped keratopathy following intravitreal silicone oil injection in an aphakic eye. J Clin Res Ophthalmol 7(1): 018-020. DOI: 10.17352/2455-1414.000066
- ↑ Coman Cernat CC, Munteanu M, Malita D, Stanca S, Patoni Popescu SI, Musat O, Negru S, Feier H, Karancsi OL, Rosca C. Corneal endothelial changes induced by pars plana vitrectomy with silicone oil tamponade for retinal detachment. Exp Ther Med. 2021 Sep;22(3):961. doi: 10.3892/etm.2021.10393. Epub 2021 Jul 7. Erratum in: Exp Ther Med. 2022 Dec 06;25(1):48. doi: 10.3892/etm.2022.11747. PMID: 34335903; PMCID: PMC8290465.
- ↑ Miller JB, Papakostas TD, Vavvas DG. Complications of emulsified silicone oil after retinal detachment repair. Semin Ophthalmol. 2014 Sep-Nov;29(5-6):312-8. doi: 10.3109/08820538.2014.962181. PMID: 25325856.
- ↑ Reed DC, Juhn AT, Rayess N, Hsu J, Chiang A. Outcomes of retinal detachment repair after posterior open globe injury. Retina. (2016) 36:758–63. 10.1097/IAE.0000000000000772
- ↑ Wickham L.J., Asaria R.H., Alexander R., Luthert P., Charteris D.G. Immunopathology of intraocular silicone oil: Retina and epiretinal membranes. Br. J. Ophthalmol. 2007;91:258–262. doi: 10.1136/bjo.2006.103549
- ↑ 9.0 9.1 Chan Y.K., Cheung N., Chan W.S.C., Wong D. Quantifying silicone oil emulsification in patients: Are we only seeing the tip of the iceberg? Graefe’s Arch. Clin. Exp. Ophthalmol. 2015;253:1671–1675. doi: 10.1007/s00417-014-2866-1.
- ↑ 10.0 10.1 Foulks GN, Hatchell DL, Proia AD, Klintworth GK. Histopathology of silicone oil keratopathy in humans. Cornea. 1991 Jan;10(1):29-37. PMID: 2019104.
- ↑ 11.0 11.1 11.2 11.3 Ferrara M, Forbice E, Segala D, et al. Multimodal imaging and histopathological evaluation in silicone oil keratopathy. European Journal of Ophthalmology. 2024;0(0). doi:10.1177/11206721241286252
- ↑ Sternberg P, Hatchell DL, Foulks GN, Landers MB. The Effect of Silicone Oil on the Cornea. Arch Ophthalmol. 1985;103(1):90–94. doi:10.1001/archopht.1985.01050010096027
- ↑ Bennett, Steven R.. (1990). Band Keratopathy From Emulsified Silicone Oil. Archives of Ophthalmology, 108(10), 1387–. doi:10.1001/archopht.1990.01070120033016
- ↑ Chan Y.K., Cheung N., Chan W.S.C., Wong D. Quantifying silicone oil emulsification in patients: Are we only seeing the tip of the iceberg? Graefe’s Arch. Clin. Exp. Ophthalmol. 2015;253:1671–1675. doi: 10.1007/s00417-014-2866-1
- ↑ Francis J.H., Latkany P.A., Rosenthal J.L. Mechanical energy from intraocular instruments cause emulsification of silicone oil. Br. J. Ophthalmol. 2007;91:818–821. doi: 10.1136/bjo.2006.103994.
- ↑ Ferrara M, Coco G, Sorrentino T, Jasani KM, Moussa G, Morescalchi F, Dhawahir-Scala F, Semeraro F, Steel DHW, Romano V, Romano MR. Retinal and Corneal Changes Associated with Intraocular Silicone Oil Tamponade. J Clin Med. 2022 Sep 5;11(17):5234. doi: 10.3390/jcm11175234. PMID: 36079165; PMCID: PMC9457190.
- ↑ Teke MY, Elgin U, Sen E, Ozdal P, Ozturk F. Intravitreal silicone oil induced changes in corneal biomechanics. Int Ophthalmol. 2014 Jun;34(3):457-63. doi: 10.1007/s10792-013-9830-7. Epub 2013 Jul 16. PMID: 23856983.
- ↑ Sayegh, B. T. J. S. O. P. P. C. G. M. M. a. R. R., MD. (2017, January 15). A Hands-on Approach to Band Keratopathy. Review of Optometry. https://www.reviewofoptometry.com/article/a-handson-approach-to-band-keratopathy
- ↑ Casswell AG, Gregor ZJ. Silicone oil removal. I. The effect on the complications of silicone oil. Br J Ophthalmol. 1987 Dec;71(12):893-7. doi: 10.1136/bjo.71.12.893. PMID: 3426994; PMCID: PMC1041339.
- ↑ 20.0 20.1 Donaghy CL, Vislisel JM, Greiner MA, Goins KM, Wagoner MD. Calcific Band Keratopathy. June 2, 2015; Available from: https://eyerounds.org/cases/214-band-keratopathy.htm
- ↑ Beekhuis WH, van Rij G, Zivojnović R. Silicone oil keratopathy: indications for keratoplasty. Br J Ophthalmol. 1985 Apr;69(4):247-53. doi: 10.1136/bjo.69.4.247. PMID: 3888251; PMCID: PMC1040576.
- ↑ 22.0 22.1 Lee GA, Shah P, Cooling RJ, Dart JK, Bunce C. Penetrating keratoplasty for silicone oil keratopathy. Clin Exp Ophthalmol. 2001 Oct;29(5):303-6. doi: 10.1046/j.1442-9071.2001.00438.x. PMID: 11720156.
- ↑ Iyer G, Srinivasan B, Gupta J, Rishi P, Sen PR, Bhende P, Gopal L, Padmanabhan P. Boston keratoprosthesis for keratopathy in eyes with retained silicone oil: a new indication. Cornea. 2011 Oct;30(10):1083-7. doi: 10.1097/ICO.0b013e318213a8b5. PMID: 21705878.
- ↑ Iyer G, Srinivasan B, Agarwal S, Pattanaik R, Rishi E, Rishi P, Shanmugasundaram S, Natarajan V. Keratoprostheses in silicone oil-filled eyes: long-term outcomes. Br J Ophthalmol. 2019 Jun;103(6):781-788. doi: 10.1136/bjophthalmol-2018-312426. Epub 2018 Jul 18. PMID: 30021817.
- ↑ Karel I, Kalvodová B, Kuthan P. Results of penetrating keratoplasty in bullous silicone oil keratopathy. Graefes Arch Clin Exp Ophthalmol. 1998 Apr;236(4):255-8. doi: 10.1007/s004170050073. PMID: 9561356.
- ↑ Noorily SW, Foulks GN, McCuen BW. Results of penetrating keratoplasty associated with silicone oil retinal tamponade. Ophthalmology. 1991 Aug;98(8):1186-9. doi: 10.1016/s0161-6420(91)32155-9. PMID: 1923354.
