SEVERE CIRCULATORY DISTURBANCE IN OPTIC DISK, RETINA, AND CHOROID AFTER SUB-TENON TRIAMCINOLONE ACETONIDE INJECTION FOR POSTERIOR SCLERITIS

Severe circulatory disruptions in the optic disk, choroid, and retina following a sub-Tenon injection of triamcinolone acetonide (STTA) in an 84-year-old man with bilateral scleritis and complex medical history. The report highlights heightened caution in administering STTA to patients with intricate medical backgrounds because of exacerbation of visual decline.

Abstract

Purpose:

To report a rare case of optic disk and chorioretinal vascular occlusions in the right eye after sub-Tenon injection of triamcinolone acetonide (STTA) in an older male patient with scleritis and to discuss the associated risk factors and potential alternative therapies.

Methods:

The medical history and clinical examination, including fundoscopy, fluorescein angiography (FA), and indocyanine green angiography (ICGA), were conducted to diagnose and evaluate the extent of vascular occlusion after STTA. An extensive literature review was undertaken to ascertain the associated risks and consider other treatment options for scleritis.

Results:

Severe circulatory disturbances in the optic disk and chorioretinal regions of the right eye developed after STTA for exacerbated scleritis, as confirmed by FA and ICGA, resulting in a significant decrease in visual acuity. A complex medical history encompassing ophthalmic and systemic health issues may have contributed to this negative outcome. A literature review pointed out the potential complications of STTA and highlighted alternative approaches to scleritis management.

Conclusion:

Cautious application of STTA in treating scleritis is crucial, especially in patients with preexisting vascular or ocular conditions. Thus, a multidisciplinary approach and a careful assessment of various treatment options are vital to minimize the risk of severe complications and improve patient outcomes.

Scleritis, characterized by scleral inflammation, is a severe ocular condition that can lead to visual impairment when left untreated. Thus, prompt and effective management is crucial for preventing vision-threatening complications, including corticosteroid administration to alleviate inflammation. For example, sub-Tenon injection of triamcinolone acetonide (STTA) has been used because of its potential to deliver a high concentration of the medication to affected tissues, with lower systemic absorption.

Although STTA is considered safe and effective, complications may still arise. Various issues associated with sub-Tenon anesthesia were reported, and preventive measures to reduce risks were highlighted.¹ Although their focus was on anesthesia, the procedural similarities provide valuable insight into potential complications and their prevention during STTA.

Furthermore, chorioretinal circulatory disturbances after STTA have been reported. Moshfeghi et al documented a case where chorioretinal vascular occlusion occurred postinjection, drawing attention to this severe, albeit rare, complication²; however, the mechanism of vascular occlusion after STTA remains unclear. It is thought to be related to the direct compression of the optic nerve or retinal vessels or a rise in intraocular pressure (IOP) postinjection.

We aimed to report a unique case of a patient with scleritis who developed severe circulatory disturbances in the optic disk, retina, and choroid after STTA, drawing comparisons and distinctions from previously reported cases, discuss the potential mechanisms of this serious complication, and explore preventive measures and alternative treatment modalities for scleritis to minimize the risks of such vascular occlusions.

Case Report

An 84-year-old man with a decade-long history of bilateral glaucoma and cataract extraction in the right eye presented with worsening conjunctival hyperemia in the right eye. His medical history included pacemaker implantation for arrhythmia 15 years earlier and cerebellar infarct 10 years managed with ongoing anticoagulation therapy.

Patient was diagnosed with bilateral scleritis 3 years before his visit to our hospital and was treated with oral nonsteroidal anti-inflammatory drugs (NSAIDs), topical fluorometholone, and STTA. Despite these treatments, suboptimal IOP control and progressive visual field impairment (Figure 1A) necessitated a bilateral microhook trabeculotomy 2 years later. The hyperemia in the right eye persisted and worsened (Figure 1B), prompting another STTA.

Fig. 1.

Examination findings of the right eye before sub-Tenon triamcinolone acetonide (STTA) injection. A. The 10-2 Humphrey field analyzer (HFA). It reveals a significant glaucomatous visual field defect, particularly affecting central vision, indicating advanced glaucoma in the right eye. B. Slit-lamp examination. A notable exacerbation of hyperemia in the right eye, as evidenced during the slit-lamp examination, emphasizing the patient's presenting ocular inflammatory condition. C. Optical coherence tomography (OCT) image. The horizontal image shows the presence of the retinal pigment epithelial and choroidal folds. These morphologic alterations may indicate underlying posterior scleritis or choroidal vascular congestion.

Before the latest STTA, the visual acuity (VA) was 20/400 in the right eye and 20/20 in the left eye, with an IOP of 10 mmHg in both eyes. The diminished VA in the right eye was attributed to advanced glaucoma. Axial length was 25.5 mm for both eyes. Optical coherence tomography (OCT) revealed retinal pigment epithelium and choroidal folds in the right eye (Figure 1C), indicative of potential posterior scleritis, choroidal vascular congestion, or a choroidal mass. The STTA was performed on the right eye without complications by an ophthalmologist with more than 15 years of experience. Specifically, a dose of 20 mg in a volume of 0.5 mL of triamcinolone acetonide (MaQaid, Wakamoto Pharmaceutical, Tokyo, Japan) was administered. A 25-gauge, 22-mm straight, blunt disposable needle (Nipro disposable ophthalmic needle 00-223, Inami & Co., Ltd., Tokyo, Japan) was used. The needle was modified by bending it to match the curvature of the globe, gently advanced, and the triamcinolone acetonide injection was administered approximately 5 mm posterior to the limbus in the inferonasal quadrant.

The IOP of the right eye remained within normal limits 2 weeks post-STTA, and a retinal hemorrhage and white preretinal lesion near the optic disk were also detected (Figure 2A). Optical coherence tomography (OCT) revealed a mass with increased reflectivity covering the optic disk (Figure 2B). The ultra-widefield fundus image depicted white embolic particulate matter covering the optic disk, suggesting probable corticosteroid injection into these masses. The VA in the right eye decreased markedly with the hand motion. These findings were supported by delayed chorioretinal circulation as evidenced by fluorescein angiography (FA) and indocyanine green angiography (ICGA) (Figure 3A). Furthermore, the OCT of the macula did not show the expected double fan-shaped moderate reflectivity within the retinal arterioles and venules (Figure 3B), suggesting insufficient blood flow. Given the weeks elapsed since the onset of these vascular events, the prognosis was poor, with aggressive intervention unlikely to be beneficial. Follow-up at 2 months showed that the VA in the right eye further deteriorated to no light perception.

Fig. 2.

Ultra-widefield fundus image and OCT image of the optic disk imaging findings of the right eye 2 weeks post-STTA. A. Ultra-widefield fundus image. It reveals extensive retinal hemorrhages and optic nerve edema, as well as the presence of white embolic particulate matter, which are consistent with corticosteroid characteristics. In addition, there is noticeable retinal whitening centered around the optic nerve. B. The OCT imaging of the right eye optic disk. Vertical OCT image after STTA shows a mass with increased reflectivity covering the optic disk (red arrows). Considering that the ultra-widefield fundus image showed white embolic particulate matter at the same location, the observed mass was likely an injected corticosteroid.

Fig. 3.

Fluorescein angiography (FA), indocyanine green angiography (ICGA), and OCT imaging of the macula of the right eye 2 weeks post sub-Tenon triamcinolone acetonide (STTA) injection. The FA (A) shows discernible retinal vascular occlusion with preserved choroidal perfusion, as evidenced by the maintained choroidal flow on ICGA. B. This contrast highlights the localized vascular impairment within the retinal vasculature post-STTA injection. Both images were captured 100 seconds after injecting the contrast agent. The horizontal OCT image of the right eye macula post-STTA (C) reveals a marked increase in the reflectivity of the inner retinal layer and the absence of the expected double fan-shaped moderate reflectivity within the retinal arterioles and venules. These findings suggested insufficient blood flow, consistent with the occurrence of retinal vascular occlusion.

Discussion

The utilization of sub-Tenon injections transcends STTA treatment to include anesthesia administration. The underlying mechanism of sub-Tenon anesthesia, inducing numbness and akinesia, primarily relies on interrupting nerve transmission to ocular structures. Upon injecting an anesthetic solution into the sub-Tenon space, diffusion into adjacent tissues occurs, leading to the blockage of nerve impulses, thereby inducing anesthesia and akinesia in the eye.³

The optic disk receives its vascular supply from the short posterior ciliary arteries (SPCAs), which traverse the sub-Tenon space near the optic disk. Consequently, exceedingly posterior placement of a metal cannula has the potential to inflict damage on these diminutive arteries, thus precipitating anterior ischemic optic neuropathy.³ It has been reported that these SPCAs occasionally extend their vascular supply into the retinal circulation, typically seen as the cilioretinal artery. These vascular connections could potentially explain the retinal infarcts associated with sub-Tenon block.⁴ The use of a long metal cannula capable of reaching the optic nerve head is known to have inherent risks,⁵ including the possibility of perforating the optic nerve sheath, which could lead to brainstem anesthesia.⁶

In our case, an experienced ophthalmologist with over 15 years of practice performed STTA using a blunt needle following standard protocols. The procedure resulted in no ocular pain or retrobulbar hemorrhage. However, severe infarcts were observed in both retinal and choroidal vasculature around the optic disk and macula during ultra-widefield fundus examination. Funduscopic examination revealed white particles covering the optic disk, and OCT imaging showed a mass of increased reflectivity over the optic disk, presumed to be a subretinal, intraretinal, and preretinal deposition of triamcinolone acetonide.

The route of triamcinolone administration in our case remains uncertain, with possible pathways including intravascular, intrathecal, and transscleral routes. Moshfeghi et al² reported a similar case involving a patient with sarcoidosis and cystoid macular edema, who was treated with STTA using a 40 mg dose administered in a volume of 1 mL through a 25-gauge needle. Their findings of retinal hemorrhages and white particulate emboli suggested severe circulatory disturbances, probably via an intravascular route. In contrast, in our case, the absence of clear retinal hemorrhages or emboli in the retinal vasculature suggests that the needle did not enter the vasculature directly. However, given the patient's advanced age and history of cerebrovascular events, we could not exclude the possibility of inherent vascular fragility. Our patient's history of recurrent scleritis, long axial length, and advanced glaucoma, along with retinal whitening around the optic disk and choroidal circulation disturbances, may have increased the fragility of the sclera and lamina cribrosa, potentially facilitating transscleral and possibly intrathecal migration of triamcinolone. This case highlights the complex risks associated with STTA in patients with extensive ocular history.

The observed adverse events, such as retinal vascular occlusion after STTA, suggest the need for caution when using this treatment for scleritis, particularly in patients with complex medical histories. Although STTA has been shown to be effective in alleviating the symptoms of persistent scleritis, it is associated with potential risks, including conjunctival necrosis, infectious scleritis, and postinjection ocular hypertension.^7,8 These complications underscore the importance of careful patient selection and careful postoperative monitoring to minimize adverse outcomes.

Consideration of alternative treatment strategies may be beneficial for patients with known comorbidities. A pharmacotherapeutic approach that includes oral NSAIDs and corticosteroids, supplemented by antimetabolites or biologic agents in cases resistant to initial treatment, may offer a comprehensive range of options.⁹ In addition, the emergence of biologic treatments targeting specific cytokines may provide a more effective and potentially safer way to treat scleral inflammation.¹⁰

In conclusion, this case highlights the potential severe complications that can arise from STTA in managing scleritis. Meticulous patient selection, thorough preprocedural assessment, and exploration of alternative or adjunctive treatment modalities could prove instrumental in preventing severe complications, ensuring the overall well-being of patients, and optimizing the management of scleritis and other ocular inflammatory conditions.