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A 40-year-old male with a history of retinal detachment presented to the ophthalmic emergency department with blurred vision. Previous records revealed that his right eye, about two years prior, had a total retinal detachment with breaks, proliferative vitreoretinopathy (PVR), choroidal detachments, and a dense cataract with synechiae. At that time, he underwent a complex retinal detachment repair with pars plana vitrectomy, choroidal drainage, membrane peel, scleral buckle placement, and lensectomy/capsulectomy. Perfluorooctane (PFO) was utilized during the surgery to flatten the detached retina, and silicone oil (SO) was then introduced. After surgery, his visual acuity had improved from light perception to 20/200. Postoperative fundus photography and optical coherence tomography (OCT) are presented for review (Figures 1 and 2).

The patient was unfortunately lost to follow-up for over one year until he returned to the emergency department again with decreased vision. At this visit, the visual acuity was hand motion in the right eye and 20/30 in the left eye. Intraocular pressures were 17 and 12 in the right and left eyes, respectively. The right pupil was 5mm and nonreactive; the left was normal. Slit lamp examination in the right eye was significant for mild conjunctival injection. The anterior chamber was deep and quiet with the exception of small, emulsified silicone oil droplets superiorly. There was a patent peripheral iridotomy present, and the lens/capsule complex was absent. The vitreous cavity was filled with silicone oil and the fundus findings can be seen in the attached images (Figures 3 and 4).

Complex retinal detachments and Silicone Oil

Retinal detachments may be complicated by a number of factors. The number and size of retinal breaks, chronicity and extent of detachment, age of the patient, and other comorbid ophthalmic conditions all play a role in surgical decision-making and the anticipated outcome. One of the most difficult aspects of a complex retinal detachment is the presence of proliferative vitreoretinopathy or PVR. PVR refers to contractile membranes that can form both above and below the retinal surface. Clinically, it appears as a whitish band or in a branching configuration, called a starfold. It is most commonly associated with chronic retinal detachments, intraocular inflammation, vitreous hemorrhage, prior intraocular surgery or trauma, choroidal detachment, larger extent of retinal detachment, and retinal breaks[1]. PVR is the leading cause of retinal detachment repair failure and, when identified, surgeons may be more likely to utilize the vitreous substitute silicone oil rather than gas.

Silicone oil (SO) has been used in retinal detachment surgery since the early 1960s[2]. Unlike gas, SO will remain inside the eye until it is surgically removed. This may be helpful in patients who have difficulty positioning, when longer tamponade is desired, or if high-altitude travel is planned as it is not expansile under lower atmospheric pressure. However, one of the major problems of SO inside of the eye is the risk for emulsification. Emulsification occurs when large oil bubbles are sheared into smaller droplets that do not re-integrate. These droplets may travel and lead to complications such as corneal decompensation, glaucoma, and vision loss. Oil may migrate into the retina, angle, uvea, optic nerve, or even into the ventricles of the brain[3, 4]!

Silicone oil for ophthalmic use is available in two viscosities: 1000 centistoke and 5000 centistoke. Though they both have equivalent surface tensions, 1000cs SO is less viscous and may therefore be more easily used through small surgical instruments. This decreased viscosity has a downside, however, in that it is also more easily emulsified. A couple of studies comparing postoperative findings of high vs low viscosity SO in retinal detachment repairs found that anatomic success, visual acuity outcomes, and complication rates were similar in both groups[5, 6]. Another study revealed similar visual acuity and anatomical outcomes between the two groups but noted a significantly higher proportion of early SO emulsification in the 1000cs group requiring early SO removal[7].

Why the drastic change in our patient’s fundus appearance?

Over the course of a year, our patient had a significant change in not only his visual acuity but also in the appearance of the retina. How did this happen, and what is going on here? Our patient had surgical repair of his retinal detachment with 1000cs silicone oil (SO) placed inside of the eye. When he returned to the emergency department much later, emulsified SO was seen in the anterior chamber and was also scattered across the retinal surface, appearing as whitish patches. On OCT imaging, small preretinal hyperreflective bodies, most likely accumulation of SO microbubbles, are appreciable. The posterior edge of the primary SO bubble can also be visualized.

What happens next?

Although SO can remain in the eye indefinitely, most surgeons recommend removal to reduce the risk of complications. This may be done as soon as three months postoperatively, but timing should be decided based on each unique case[8]. Fortunately, in cases of preretinal emulsified oil, removal of the oil will likely lead to improved visual acuity[9]. If we, as optometrists, encounter a case such as this, it is important to refer them back to a vitreoretinal surgeon for further management.

Regardless of a patient’s decision to pursue further surgical intervention, long-term monitoring is critical as patients are still at risk of complications such as recurrent retinal detachment, development of secondary glaucoma, or corneal decompensation.

Figure 1: Fundus photo after retinal detachment repair.
Figure 2: OCT after retinal detachment repair. Green arrow denotes subretinal PFO bubbles. Retina is flat and intact otherwise.
Figure 3: Fundus photo after being lost to follow-up for over one year. Diffuse retinal whitish glistening patches reveal dispersed emulsified silicone oil.
Figure 4: OCT after being lost to follow-up for over one year. Blue arrow denotes hyperreflective tiny preretinal bodies, likely emulsified silicone oil microbubbles. Green arrow denotes posterior edge of primary silicone bubble. Orange arrow denotes subretinal PFO.

 

Citations

  1.     Idrees, S., J. Sridhar, and A.E. Kuriyan, Proliferative Vitreoretinopathy: A Review. Int Ophthalmol Clin, 2019. 59(1): p. 221-240.
  2.     Cibis, P.A., et al., The use of liquid silicone in retinal detachment surgery. Arch Ophthalmol, 1962. 68: p. 590-9.
  3.     Miller, J.B., T.D. Papakostas, and D.G. Vavvas, Complications of emulsified silicone oil after retinal detachment repair. Semin Ophthalmol, 2014. 29(5-6): p. 312-8.
  4.     Cao, S., et al., Moving silicone oil particles in the ventricle: a case report and updated review. BMC Ophthalmol, 2022. 22(1): p. 96.
  5.     Scott, I.U., et al., Outcomes of complex retinal detachment repair using 1000- vs 5000-centistoke silicone oil. Arch Ophthalmol, 2005. 123(4): p. 473-8.
  6.     Ratanapakorn, T., et al., Emulsification of Different Viscosity Silicone Oil in Complicated Retinal Detachment Surgery: A Randomized Double-Blinded Clinical Trial. Clin Ophthalmol, 2020. 14: p. 359-367.
  7.     Zafar, S., et al., Comparison of 1000-Centistoke versus 5000-Centistoke Silicone Oil in Complex Retinal Detachment Surgery. J Coll Physicians Surg Pak, 2016. 26(1): p. 36-40.
  8.     Falkner, C.I., S. Binder, and A. Kruger, Outcome after silicone oil removal. Br J Ophthalmol, 2001. 85(11): p. 1324-7.
  9.     Nagpal, M., et al., Correlation of spectral domain optical coherence tomography findings in sub-silicone oil foveal depression space and visual outcome in eyes undergoing silicone oil removal. Taiwan J Ophthalmol, 2016. 6(1): p. 21-25.

 

Alison Bozung
Practicing at Bascom Palmer Eye Institute, primarily seeing patients in the ophthalmic emergency department.

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