Abstract
Purpose:
To report a novel cause of post-operative reversible visual distortion due to a persistent air bubble sequestered at the intraocular lens (IOL)–silicone oil interface.
Methods:
Two cases of persistent, sequestered air at the IOL-silicone oil interface were identified and reviewed. Relevant clinical information, images and surgical videos were analyzed and described.
Results:
Resolution of the visual distortion was achieved in both cases after silicone oil removal.
Conclusions:
Silicone oil adhesion to the posterior surface of silicone IOLs is a known cause of visual degradation. The IOL-silicone oil interface can sequester air that persists and causes visual distortion until the oil is removed. We report the first cases, to our knowledge, of reversible visual distortion due to sequestered air at the IOL-silicone oil interface.
Keywords: silicone oil, vitreoretinal surgery, retina
Introduction
Silicone oil is commonly used for complex retinal detachment repair. Although generally well tolerated, silicone oil is the source of both reversible and irreversible vision loss due to keratopathy, 1 secondary glaucoma, 2 cataract, 3 emulsification, 4,5 macular edema, 5 retinal and optic nerve infiltration, 6 and translaminar intracranial migration. 7
First reported in 1996, the adhesion of silicone oil to the posterior surface of intraocular lenses (IOLs), especially those made of silicone, has been widely cited as a cause of visual degradation. 8 Since then, other silicone oil–IOL complications have been described, such as the calcification and granular opacification of hydrophilic acrylic IOLs. 9
We describe 2 cases of a persistent air bubble sequestered in the visual axis at the silicone oil–IOL interface as a novel cause of reversible visual distortion.
Methods
Report of Cases
Case 1
An 82-year-old man was referred for decreased vision in the right eye. He had a history of high myopia in both eyes (–11 diopters), and he had previously undergone cataract extraction with silicone IOL implantation (SI30NB, Abbott Medical Optics) as well as yttrium-aluminum-garnet (YAG) capsulotomy in the right eye. In the left eye, he reportedly had a remote history of retinal detachment due to a giant retinal tear for which he had undergone vitrectomy, lensectomy, and scleral buckle with resultant counting fingers vision. Visual acuity (VA) in the right eye was 20/200 secondary to a chronic, shallow macula-off inferior rhegmatogenous retinal detachment. The patient underwent successful vitrectomy, retinal reattachment, and silicone oil tamponade in the right eye. Postoperatively, the patient noticed distortion in his central vision. His VA was 20/800, and an air bubble was observed in the visual axis sequestered between the IOL and the silicone oil that did not change in appearance during the postoperative period (Figure 1A). The retina remained attached.
Figure 1.
Sequestered air at the intraocular lens—silicone oil interface (A) before and (B) after silicone oil removal. (C) A second case of air at the intraocular lens—silicone oil interface.
The silicone oil was removed 4 months later. During the procedure, the air bubble was aspirated with a 25-gauge needle (video supplement) and the silicone oil was removed. There was residual silicone oil adherent to the posterior surface of the IOL that was partially removed with the 23-gauge vitrector. After a partial fluid-air exchange, the vitrector was attached to a syringe filled with a balanced salt solution with the port directed toward the posterior IOL surface to irrigate, or “power wash,” the residual silicone oil away. Postoperatively, the patient reported resolution of the visual distortion, and his VA improved to 20/400 (Figure 1B).
Case 2
A 69-year-old woman with a history of cataract extraction and silicone IOL implantation in both eyes (LI61AO, Bausch + Lomb) and YAG capsulotomy in the right eye was referred for decreased vision in her right eye. Her VA was hand motion in the right eye due to an open-funnel total retinal detachment with severe anterior and posterior proliferative vitreoretinopathy. She underwent vitrectomy with extensive membrane peeling and 360° retinectomy with insertion of silicone oil. Her VA improved to counting fingers. An air bubble was observed slightly eccentric to the visual axis sequestered between the IOL and the silicone oil, and it did not change in appearance during the postoperative period (Figure 1C). The retina remained attached. She had appreciated distortion and warping of her vision postoperatively.
The silicone oil and the persistent air bubble were removed 11 months later. There was residual silicone oil adherent to the posterior surface of the IOL, and a similar technique as described in case 1 was used to irrigate the residual oil away. Postoperatively, the patient reported resolution of the visual distortion, and her VA remained at counting fingers.
Results
Persistent air sequestered between a silicone IOL and silicone oil can lead to reversible visual distortion if present in the visual axis. To our knowledge, this finding has not been previously reported as a cause of vision loss related to silicone oil or silicone IOLs.
The presence of this finding raises questions of how the air bubble arises, becomes fixed at the posterior IOL plane, and interestingly, fails to dissolve during the postoperative period. In both of our cases, the vitreous cavity had a seemingly complete silicone-oil fill to the level of the IOL, and there was no air bubble observed intraoperatively or even immediately postoperatively. This suggests that there was migration of a small residual air bubble, or there were bubbles within the oil or between the iris and the oil, and the air became entrapped between the hydrophobic IOL and the hydrophobic oil. An open posterior capsule, as was present in both cases owing to a prior YAG capsulotomy, may be an essential precondition to air sequestration.
One can further speculate about the causative mechanism. In both cases, the IOL appeared to be properly oriented within the capsule; however, if the superior extent of the hydrophobic IOL is tilted slightly posteriorly, it may be possible that the superior edge of the IOL creates an asymmetric adhesion with the silicone oil relative to the inferior portion and acts as a barrier that entraps small air bubbles. Alternatively, the location of the air bubble may simply be due to chance. Air typically disappears from the vitreous cavity within a few days because of diffusion of its individual gases into the surrounding fluid. We propose that when air is in contact with an IOL and silicone oil but has no contact with intraocular fluid or tissues, it is unable to dissolve, which accounts for its persistence until the silicone oil is removed.
Both patients had compromised vision at baseline. The sequestered air presumably would have been more visually significant had there been better visual potential.
Conclusions
Unlike most causes of vision loss due to silicone oil, sequestered air does not have any deleterious effects and resolves with the silicone oil removal. In case 1, we removed the air bubble with needle aspiration to confirm that this was air and not fluid or oil, as demonstrated in the video supplement. In both cases, residual silicone oil was adherent to the posterior surface of the IOL even after oil removal. This material is difficult to remove, but a combination of aspiration and directed irrigation either with the vitrector or a cannula often removes most of the residual oil. 10 In vitro and in vivo studies have shown that some experimental materials have promise in aiding silicone oil removal. 11 Adherent oil left on the IOL can cause refractive changes, visual aberrations, and distortion, and for these reasons silicone IOLs should be avoided in eyes with increased risk of retinal detachment.
Eyes with silicone IOLs and open posterior capsules are at risk for silicone oil adhesion to the posterior surface of the IOL. This report demonstrates that air can become sequestered at the IOL–silicone oil interface and may persist until the oil is removed. This phenomenon can cause visual distortion that resolves with the silicone oil removal.
Supplemental Video
Footnotes
Ethical Approval: This report was conducted in accordance with the Declaration of Helsinki. The collection and evaluation of all protected patient health information was performed in a Health Insurance Portability and Accountability Act (HIPAA)–compliant manner.
Statement of Informed Consent: Informed consent was obtained prior to performing the procedures, including permission of obtaining all photographs and images included herein. Personally identifying information is not presented.
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding: The author(s) received no financial support for the research, authorship, and/or publication of this article.
ORCID iD: Joshua S. Agranat, MD 
https://orcid.org/0000-0001-5310-0353
Supplemental Material: Supplemental material is available online with this article.
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