Curvularia infection of corneoscleral tunnel.

Corneoscleral tunnel infection is a potentially sight threatening complication of cataract surgery. Microbiological investigations are mandatory and early surgical intervention helps in achieving favourable outcomes. Fungal infection of tunnel incisions can pose a diagnostic and therapeutic challenge. We report a case of post-operative tunnel infection with curvularia. Prompt surgical intervention and intensive topical therapy helped attain a good tectonic as well as visual recovery.

Corneoscleral tunnel infection post cataract surgery is a potentially devastating clinical situation. The self-sealing scleral incision may serve as a nidus for intra-scleral abscess cavity in the event of an infection.[1] Tunnel infections have been described both in cases of manual small incision cataract surgery and phacoemulsification. An improperly constructed wound, loose or broken sutures, and associated dacryocystitis have been identified as important predisposing conditions.[2] Tunnel infections have been attributed to both bacteria and fungus. Aspergillus has been the most commonly implicated fungus in the previously reported case series.[23] We report a case of corneoscleral tunnel infection with the dematiaceous fungus, Curvularia, and its successful management. To the best of our knowledge, this is the first reported case of Curvularia causing a tunnel infection.

Case Report

A 60-year-old female presented to the cornea services of our hospital with complaints of pain, decreased vision and discharge in her right eye for the past 15 days. She had undergone cataract surgery (phacoemulsification) with intra-ocular lens implantation (IOL) in her right eye one month ago elsewhere. Intra-operative details of the surgery were not available. She was a well-controlled diabetic on oral hypoglycaemic drugs. At presentation, she was on topical therapy with eye drop moxifloxacin (0.3%) one hourly. Her best corrected distance visual acuity (BCVA) was counting finger close to face in the right eye and 20/40 in the left eye. Slit lamp bio-microscopy of right eye revealed congested conjunctiva with dense white infiltrate at the scleral tunnel in the supero-temporal quadrant with involvement of 2 mm of peripheral cornea. There were Descemet's membrane folds, 4+ anterior chamber cells, peaked pupil and a fibrinous membrane over the IOL [Fig. 1a and b]. Seidel's test was negative. Fundoscopy revealed a poor glow and posterior segment details could not be appreciated. B-scan ultrasonography showed a clear vitreous cavity with attached retina. Left eye had a clear cornea, grade 2 nuclear sclerosis and a normal retina and optic nerve. Lacrimal drainage system was patent in both the eyes. Random blood sugar was 112 mg%. Diagnostic scraping was performed from the scleral and the corneal infiltrates which demonstrated fungal hyphae on KOH staining. An immediate tunnel de-roofing with corneoscleral patch graft was performed under local anaesthesia in the right eye. A clear margin of 1 mm all around was aimed at while excising the infected tissue. The patch graft was sutured with 9-0 nylon sutures on the scleral side and 10-0 nylon suture on the corneal side. The surgery was uneventful. The excised corneoscleral tissue showed fungal growth on blood agar, chocolate agar and Sabouraud's dextrose agar on third post-operative day. On the eighth day microscopy from the growth revealed septate brown hyphae, conidia and brown conidiophores with transverse septa dividing each conidium into multiple cells, with typical swelling of the central cell and the sympodial geniculate growth pattern suggestive of Curvularia lunata [Fig. 2]. This was then confirmed on LCB mount. Post-operative day one, patient was started on topical natamycin (5%) one hourly, homatropine (2%) 3 times a day and carboxy-methyl cellulose 6 times a day along with oral ketoconazole tablet (200 mg) twice a day for 1 week. After 2 weeks, eye drop prednisolone phosphate (1%) was added 4 times a day. Patient was kept on a regular follow-up and showed no recurrence of infection. At 8 months post-operative visit, patient had a well apposed patch graft, clear central cornea and a quiet anterior chamber [Fig. 3]. Fundus was normal on indirect ophthalmoscopy. BCVA for distance improved to 20/50. The patient was advised a regular 2 monthly follow up.

Figure 1

(a) Slit lamp photograph of right eye in diffuse illumination at the day of presentation showing conjunctival chemosis with whitish infiltration and sloughing of corneoscleral tunnel. Slit view (b) shows cells and flare in the anterior chamber

Figure 2

(a) The excised corneoscleral tissue showed growth on BA, CA, SDA. (b) –KOH mount (×40) shows simple and branched brown conidiophores and straight, pyriform, brown multiseptate conidia with central cell darkened and enlarged in comparison to end cells of conidium suggestive of Curvularia lunata

Figure 3

Eight months post-operative picture showing well opposed edematous patch graft with a clear visual axis and well centred IOL

Discussion

Corneoscleral tunnel infection is a known post-operative complication of cataract surgery. It is a relative ocular emergency as it can lead to endophthalmitis which is potentially blinding. There are few reports on the clinical pattern, microbiological profile, and treatment outcomes of corneoscleral tunnel infections.[1234] The clinical picture can range from scleritis, scleral infiltration and necrosis, increased reaction in anterior chamber or keratitis, and can easily be misdiagnosed as a postoperative inflammation or surgically induced necrotising scleritis, warranting steroid as the mainstay of treatment.[3] It therefore becomes very important for the treating clinician to differentiate infection from inflammation. A strong suspicion of infection should be borne in mind when the patient presents early post cataract surgery with scleral and corneal infiltration around the surgical wound in a predisposed individual. In contrast an inflammatory pathology would present as a fairly well demarcated area of scleral necrosis with dilated episcleral vessels and excruciating pain. To differentiate infection from inflammation, any corneoscleral infiltration post cataract surgery mandates proper microbiological evaluation.

The probable source of infection can be eyelid and conjunctival flora, associated dacryocystitis, poor sterilization technique, postoperative wound leak, use of postoperative corticosteroids without antibiotics, hot and humid environment, systemic risk factors such as immunocompromised status and diabetes mellitus.[345] Our patient had well controlled diabetes mellitus, with good periocular hygiene. The probable source of infection in our case could not be ascertained. Aspergillus has been implicated as an important causative organism for corneoscleral tunnel infections in a few case series from the Indian subcontinent.[36] In our case Curvularia, a dematiaceous fungus was isolated as the infecting organism. Dematiaceous fungi are well known causative organisms for corneal ulcers. Forster et al.[7] in their series of 240 fungal keratitis reported dematiaceous fungi as the third most common isolate of which Curvularia was the most common. This is consistent with other studies[89] which also have shown similar incidence of Curvularia keratitis. To the best of our knowledge this is the first report of Curvularia as a causative agent for post-operative corneoscleral tunnel infection.

Treatment modalities available for tunnel infections include intensive medical therapy, wound re-suturing, tunnel de-roofing and patch graft and penetrating keratoplasty. Garg et al.[3] have reported a poorer outcome with fungal infections of tunnel as deep seated scleral fungal involvement have high risk of fungal persistence and recurrence even after postsurgical excision. Most of the eyes in their series progressed to phthisis bulbi. Therefore, we planned an immediate surgical intervention with wide excision of scleral margins to completely eradicate the fungal organism. Consequently, we could achieve good tectonic and visual recovery for the patient.

Conclusion

Prompt surgical intervention and intensive topical therapy may help attain a good tectonic as well as visual recovery in a patient with corneoscleral tunnel infection.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.