Toxic posterior segment syndrome caused by silicone oil tamponade resulting in postsurgical retinal vascular occlusion: a case report

Abstract

Purpose

We aimed to report a rare case of postoperative retinal vessel occlusion caused by silicone oil.

Observations

A 71-year-old male patient presented with decreased visual acuity and was diagnosed with macular hole retinal detachment (MHRD). The patient underwent pars plana vitrectomy (PPV) and was administered a silicone oil injection. The day after surgery, although inflammation and hyperemia within the anterior chamber were mild, fundus examination revealed evidence of retinal blood vessel occlusion. The patient was assumed to have contracted bacterial endophthalmitis and underwent PPV again, wherein the silicone oil was removed followed by antibiotic administration and steroid eye drops initiation. The inflammation improved 2 weeks after surgery; the patient underwent a second operation for MHRD and was administered a silicone oil injection. However, the same vascular occlusion findings were observed the day after surgery. Vascular occlusion was thought to be due to sterile inflammation rather than bacterial endophthalmitis; the inflammatory findings subsided after silicone oil removal.

Conclusions

In cases of retinal vascular occlusion occurring early after silicone oil injection, if the anterior segment inflammation is mild, the possibility of toxic posterior segment syndrome must be considered.

Abbreviations

TASS

toxic anterior segment syndrome

TPSS

toxic posterior segment syndrome

PPV

pars plana vitrectomy

MHRD

macular hole retinal detachment

PDMS

polydimethylsiloxane

ILM

internal limiting membrane

BBG

Brilliant Blue G

SF6

sulfur hexafluoride

Ig

immunoglobulin

LMWCs

low-molecular-weight components

1. Introduction

Toxic anterior segment syndrome (TASS)¹ and toxic posterior segment syndrome (TPSS)² are characterized by sterile inflammation development following internal eye surgeries. TASS is often an outcome of anterior segment surgery or cataract surgery,¹ whereas, TPSS occurs after procedures such as pars plana vitrectomy (PPV); however, its frequency of occurrence is rare. The main finding in TPSS is occlusive retinal vasculitis, an immediate reaction to PPV3, 4, 5, 6

Occlusive retinal vasculitis immediately after eye surgery is typically diagnosed as endophthalmitis. Silicone oil is a significantly stable⁷ vitreous substitute, particularly in the eyes, and has been in use in PPV procedures for 30 years.⁸ Reports of TPSS occurring after silicone oil administration are rare.3, 4, 5 We report a rare case wherein silicone oil was injected into the same eye twice. Although the patient's condition was initially treated as endophthalmitis, following recurrence of vasculitis, was subsequently diagnosed as TPSS.

2. Case report

In this study, the patient was a 71-year-old man with a history of chronic leukemia without significant allergies. The patient had severe myopia and had undergone cataract surgery 10 years prior to the visit. During the first visit, he was diagnosed with macular hole retinal detachment (MHRD), following which he underwent a 25G PPV and silicone oil tamponade in the right eye. SILIKON™ 1000 (Polydimethylsiloxane, PDMS; Alcon Laboratories, Inc. Fort Worth, TX, USA) was used as the silicone oil. Intraoperatively, internal limiting membrane (ILM) peeling was performed using triamcinolone and Brilliant Blue G (BBG). Moreover, the inverted ILM flap technique⁹ was performed using purified sodium hyaluronate. After air replacement to control the intraocular pressure to 35 mmHg, silicone oil was injected using the viscous fluid control setting to achieve a maximum injection pressure of 20 psi. On the day of surgery, the patient was placed in the prone position.

On postoperative day 1, the intraocular pressure in the right eye was 5 mmHg. Although inflammation and hyperemia within the anterior chamber were mild, the fundus showed obstruction, mainly in the nasal retinal blood vessels, accompanied by petechiae in the retina (Fig. 1). The patient did not experience any pain in the eye. It was suspected that the presence of silicone oil might have masked signs of inflammation within the vitreous cavity; therefore, the patient was diagnosed with endophthalmitis. After removing the silicone oil, vitreous irrigation was performed. Intravitreal injections of antibiotics were administered within a few hours after diagnosis. Tamponade was not performed to prioritize treatment of endophthalmitis. Endophthalmitis treatment entailed systemic administration of antibiotic eye drops, while steroid eye drops were used to eliminate inflammation. Furthermore, no bacteria were detected in the vitreous fluid cultures. Since MHRD did not resolve, the patient underwent a PPV procedure 2 weeks later when the inflammation subsided. During the third PPV procedure for the treatment of MHRD, ILM transplantation was performed using BBG. Since restricting the patient's position after surgery and maintaining the tamponade effect for a longer duration were difficult, silicone oil was injected again; the patient was placed in a prone position on the day of the surgery.

Fig. 1.

Anterior segment and fundus findings on the day after silicone oil injection

Inflammation in the anterior chamber was mild, and no fibrin was observed. The peripheral retinal vessels were white with a pinpoint hemorrhage. The arrowheads indicate areas with severe vascular occlusion.

Retinal vascular occlusion was observed on the day of the second silicone injection procedure (Fig. 2). The intraocular pressure in the right eye was 4 mmHg. Inflammation and hyperemia in the anterior chamber were mild; the patient did not experience pain. Based on these findings, we ruled out bacterial endophthalmitis and considered the patient's condition to be an inflammatory reaction caused by silicone oil. After silicone oil removal, autologous transplantation of the ILM¹⁰ using BBG and 20 % sulfur hexafluoride (SF6) tamponade were performed. The inflammatory reaction improved with silicone oil removal and administration of postoperative steroid eye drops. Three months after surgery, although the petechiae persisted, the findings of vascular occlusion improved, without MHRD recurrence; the retina was repositioned. Following steroid eye drops discontinuation 6 months postoperatively, retinal pinpoint hemorrhages almost completely disappeared (Fig. 3).

Fig. 2.

Findings the day after the second silicone oil injection

Although the inflammation in the anterior chamber was mild, the same retinal vascular occlusion findings as those after the first silicone injection were observed. The arrowheads indicate areas with severe vascular occlusion.

Fig. 3.

Findings 6 months after surgery

The retinal pinpoint hemorrhages almost completely disappeared within 6 months of surgery. Macular hole retinal detachment was reattached.

3. Discussion

In this case, we observed rare findings of vascular occlusion in the posterior segment of the eye after silicone oil injection, which was considered indicative of TPSS.

Although the patient had no conjunctival congestion, there was mild inflammation in the anterior chamber but without fibrin or hypopyon or any associated pain. Although no vitreous opacity was detected, the eye was still injected with silicone oil, and the antibacterial effect of the silicone oil might have masked the symptoms.¹¹ Therefore, the vascular occlusion was assumed to be due to endophthalmitis. However, since similar findings were observed after the second silicone oil administration too, the posterior segment inflammation, specifically TPSS, was reconsidered to be induced by silicone oil administration rather than by endophthalmitis.

TPSS is an acute immune complex reaction¹²; all substances involved in the surgical process have been reported to cause surgical toxicity.² TPSS might be accompanied by retinal hemorrhage, vasculitis, pigment epithelial lesions, and macular edema. Amigó and Martinez-Sorribes reported that papillary pallor accompanied by optic nerve atrophy may occur due to TPSS.² Previous reports have described that TPSS induced by silicone oil caused localized vascular occlusion and petechiae in the posterior segment of the eye, which is similar to the findings in the present case.

TPSS can be caused by not only silicone oil but also BBG, purified sodium hyaluronate, and oxiglutatione. However, among the four surgeries, vascular occlusion findings were observed only after the surgery involving silicone oil, despite using BBG, purified sodium hyaluronate, and oxiglutatione in the same manner; therefore, silicone oil is thought to be the cause of TPSS.

The silicone oil used in this study was PDMS. Previously, PDMS was known to contain impurities, such as linear and cyclic low-molecular-weight components (LMWCs), ionic compounds, and cleavable fluoride-containing compounds, which were thought to cause ocular toxicity.¹³ However, recently, the purity of silicone oil has increased; therefore, these impurities were unlikely related to retinal vessel occlusion in this patient.

Decompression retinopathy is a type of retinal hemorrhage that occurs after surgery or treatment.¹⁴ Certainly, it cannot be denied that the difference in intraocular pressure during and after the silicone injection might have caused retinal hemorrhage. However, in this case, there was no bleeding or edema around the optic disc, which occurs in decompression retinopathy. Additionally, the retinal vascular occlusion findings were not indicative of decompression retinopathy; therefore, the condition was considered to be TPSS.

In previous reports,^3,4 patients with TPSS were treated with oral steroids, wherein the silicone oil was removed after the symptoms of vasculitis improved; however, in our case, the silicone oil was extracted within a few hours after the vascular occlusion symptoms developed. Furthermore, steroids were administered only as eye drops, resulting in symptom improvement. This suggests that silicone oil removal is an effective treatment of TPSS.

4. Conclusions

Based on our experience, in cases of immediate postoperative retinal vascular occlusion following vitrectomy with silicone oil injection, not only endophthalmitis but also the possibility of TPSS should be considered. Notably, in this patient, the signs of TPSS improved with silicone oil removal and topical eye drops.

CRediT authorship contribution statement

Miho Kumoi: Writing – original draft, Data curation, Conceptualization. Satoshi Matsuda: Writing – review & editing. Mai Matsumoto: Investigation. Chieko Tsujino: Investigation. Yasumasa Otori: Supervision.

Patient consent

Written informed consent was obtained for publishing anonymized patient information in this article.

Ethical statement

All procedures were in accordance with the ethical standards of the Helsinki Declaration of 1964 and later versions.

Claim of priority

After conducting a literature review on July 9, 2024 utilizing PubMed and Google Scholar using the key words, silicone oil, inflammation, and toxic posterior segment syndrome, we did not find any prior reports of a patient with vasculitis after the silicone oil injection that occurred twice.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author.

Declaration of generative AI in scientific writing

None.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Glossary

TPSS, toxic posterior segment syndrome: Sterile inflammation of the posterior segment following intraocular surgery.

LMWCs, low-molecular-weight components: Impurities in silicone oil.

PDMS, polydimethylsiloxane: Main component of silicone oil.