Scleritis is more commonly associated with autoimmune disorders than with infectious etiologies . Owing to the overlap of presenting clinical features, infectious scleritis is often initially misdiagnosed and treated with corticosteroids, leading to worsening of the disease into a fulminant and relentlessly progressive clinical course. Aggressive surgical management may often be required for globe salvage in these cases. Pseudomonas, Staphylococcus, and Herpes zoster are common agents that can cause infectious scleritis which mimics autoimmune disease [8,14].
All five patients in our study had a common history of treatment with systemic steroids that may have led to worsening of their scleritis. (Table 1) Sahu et al observed that in their cohort of 17 patients with infectious scleritis, 15 were on topical steroids. The authors have attributed the worsening of infections in these patients to the inhibition of lysosomal enzymes and suppression of immunity .
Patient 1 presented to us after focal debridement and abscess drainage carried out at another facility and was treated with systemic steroids throughout because the microbiology was non-revealing. In view of the fulminant clinical picture, the patient was promptly taken up for surgical debridement. Tittler et al reported improved functional outcomes of patients with infectious scleritis who were treated with prompt and aggressive scleral debridement and antimicrobial therapy; the authors observed that a delayed debridement was associated with poorer outcomes .
Patient 2 presented two months after cataract surgery with a surgical wound infection. Infectious scleritis has been reported after various surgical procedures like pterygium excision, cataract and vitreoretinal surgery [11,17,18]. Patients with a prior history of ocular surgery and then presenting with necrotising scleritis at the site of tissue penetration should be suspected to have infectious scleritis. The presentation at two months is similar to that observed by Hodson et al; who noted that fastidious organisms had a longer time between symptoms and diagnosis than the non-fastidious ones .
Patient 3 gave a history of trauma by vegetative matter. Reddy et al noted a history of trauma in 22% of scleritis due to infectious etiology . Ahn et al observed a poorer prognosis amongst eyes with fungal scleritis, most likely due to delay in diagnosis and its rapid worsening with steroids . Jain et al observed that fungal scleritis was more commonly seen in areas of hot, humid climate and found Aspergillus and Nocardia to be the most common pathological agents. Of the eight cases of fungal scleritis, four eyes were eviscerated and only one retained useful vision despite adequate antifungal therapy and surgical debridement in their series. This highlights the need for prompt diagnosis and early, aggressive surgical debridement . Multiple scleral debridements were performed in our cases, which are frequently needed in fungal scleritis due to the increased incidence of recurrence as reported by Reddy et al .
Patient 4 initially presented with a clinical picture of acute anterior uveitis with diffuse-anterior scleritis, which worsened on corticosteroids and led to formation of scleral abscess. These abscesses are most commonly located along an arc 3-4 mm from the limbus as observed by Hsiao et al . The patient underwent an uneventful phacoemulsification and had a stable postoperative course, revealing the stability of the globe post-circumferential debridement.
Patient 5 presented with a condition mimicking nodular episcleritis. This case also highlighted the fact that infectious scleritis may be confused initially with its autoimmune counterpart and the administration of corticosteroids may be considered in a step-wise fashion. However, once the misdiagnosed infectious etiology was exposed to systemic steroids, the progression was unabated, only to culminate in a full-thickness necrotising involvement of scleral tissue - thus mandating an aggressive surgical approach.
Surgical debridement plays an important role in the management of infectious scleritis. The relative avascularity of the sclera and the dense structure of the collagen fibers hinder penetration by topical and systemic antibiotics . The picture is further complicated in infectious scleritis of fungal etiology where hyphae are enmeshed into scleral lamellae extending into the apparently uninvolved tissue. Hence surgical debridement needs to be aggressive and extensive without sparing the overlying conjunctiva. Also, debridement provides samples for microbiological analysis, further aiding establishment of definitive diagnosis and early institution of targeted therapy.
Conjunctival excision is recommended in order to prevent re-organization of abscess after surgical debridement, enhance drug-penetration and maximise elimination of infection. Tittler et al demonstrated a 100% globe preservation rate, improved visual rehabilitation and fewer complications by doing a prompt surgical debridement at diagnosis . We performed a full thickness surgical debridement in all cases, since it has been reported that aggressive early debridement not only debulks the infected scleral tissue, but also aids in antibiotic penetration [15,19].
It must however be remembered that one needs to exercise extreme caution while performing full-thickness excision of necrosed and melted scleral tissue (often with circumferential extent and cheesy consistency in steroid exposed cases) as discussed in our study. One blade of the scissors is circumferentially slid into the supra-choroidal space as far as no resistance is encountered and the affected tissue is then cut along the junction of infected and normal sclera both anteriorly and posteriorly. It has also been shown that the extent of involved sclera is better delineated intraoperatively than on clinical examination, and often the actual extent is greater, than that observed on clinical examination.
Extensive scleral debridement has also been shown to require patch-graft [7,15]. However, in our series, scleral patch graft was not resorted to; despite extensive full-thickness debridement. In our experience, application of preserved/cadaveric, avascular, scleral patch-graft at the site of active infection not only leads to persistence of infectious focus and re-organization of abscess but also necrosis of the graft. Epithelisation of the bare choroid/uveal tissue in early post-operative period was observed.
All patients were maintained on anti-glaucoma medications for an initial one month, in order to prevent spikes in intraocular pressure due to inflammation. This was necessary to prevent the dehiscence of bare-choroid in early post-operative period; and formation of ciliary staphyloma in late post-operative period – which may occur due to circumferential lack of scleral support.
Recurrences in case of infectious scleritis are rare after complete resolution as opposed to autoimmune scleritis, where frequent recurrences occur . We observed similar findings in our series where none of the patients had recurrence after scleral debridement until a follow up period of one year. The integrity of the globe was maintained as demonstrated by an uneventful phacoemulsification with intraocular lens implantation in one patient and stable postoperative course in all patients. Thus, good anatomical and visual outcome after the procedure was achieved without the use of a scleral patch graft in any case.
To conclude, infectious scleritis should be considered in patients showing inadequate clinical response to steroid therapy, reactivation/non-resolution of an existing lesion or appearance of new lesion/lesions. History of trauma may not be forthcoming in all cases especially when a trivial trauma has gone unnoticed. Full-thickness removal of infected and necrosed sclera appears to be a safe procedure in managing such cases of infectious scleritis especially following steroid exposure. This study highlights the fulminant and relentlessly progressive clinical course, that infectious scleritis can metamorphose into, despite specific anti-microbial therapy, if inadvertent corticosteroid therapy has been administered. Full-thickness debridement without scleral patch-graft could achieve elimination of infectious foci with favourable long-term anatomical and visual outcome. This technique could offer a potential last resort approach in such cases where standard therapeutic modalities have not been successful.