Sphingomonas paucimobilis keratitis in a patient with neurotrophic keratopathy and severe neurosensory hypoacusis: Treatment with penetrating keratoplasty and amniotic membrane grafting.

We describe a case of a man with neurotrophic keratitis of unknown ethiology, who developed a massive stromal melting during treatment of a persistent epithelial defect. A tectonic keratoplasty combined with amniotic membrane grafting was made. Host cornea specimen was analyzed, and Sphingomonas paucimobilis was isolated.

Introduction

Neurotrophic keratopathy is an entity consisting on corneal hypoesthesia and impaired epithelial healing. Trigeminal nerve dysfunction is usually the underlying cause. Its treatment is challenging because physiologic reaction to epithelium damage and other feedback mechanisms are lost.[1] We present a case of this entity in a patient with severe neurosensory hypoacusis, who developed an uncommon infectious keratitis and subsequent perforation, and required a penetrating keratoplasty.

Case Report

A 59-year-old male was sent from another ophthalmology department for consultation. Six months before, he presented with painless red eye. Left eye slit-lamp examination revealed a corneal epithelial defect, an underlying stromal infiltrate, anterior chamber reaction and hypopyon. No microorganism was found on three different corneal scrapes and one aqueous humor sample. Empirical treatment for bacterial, fungal, viral, and protozoan infection was prescribed during these months. Four months later, stromal infiltration and anterior chamber reaction disappeared, but epithelial defect persisted [Figure 1a–b]. He also developed a mature cataract. His medical examination and history revealed severe bilateral neurosensory hypoacusis. Neither ophthalmic pathology nor herpetic infection history was present.

Figure 1

(a and b) Slit-lamp examination showing a persistent epithelial defect and a mature cataract. (c) The image shows improvement of epithelial defect. (d) Massive stromal melting and lens extrusion can be noted in this photograph

The patient started treatment with topical autologous serum and matrix regeneration therapy (RTGA), and the epithelial defect improved [Figure 1c].

Flash visual evoked potentials and B-scan ultrasonography gave normal results. Five months later, extracapsular cataract surgery was performed with therapeutic and diagnostic purposes. No incidents occurred during surgery. Postoperative fundus examination showed large cupping of the optic nerve head.

One month later, no further improvement of the corneal pathology was noted despite the treatment. A conjunctival-limbal allotransplantation procedure was planned for improving epithelial healing.

Before the surgery could be performed, the patient presented with perforation secondary to extensive stromal melting and intraocular lens extrusion [Figure 1d]. A penetrating keratoplasty combined with amniotic membrane grafting was made.

Host cornea specimen revealed nonspecific necrotizing inflammation, with predominantly neutrophilic infiltrate [Figure 2a–b]. Sphingomonas paucimobilis was isolated from a corneal button culture.

Figure 2

(a) Microscopy image showing acute nonspecific necrotizing inflammation into hyalinized debris (H and E, ×100). (b) The neutrophils are the main component of this inflammatory cellular infiltrate (H and E, ×400)

Six months following surgery, a persistent epithelial defect appeared on the donor button. Treatment with bandage contact lens and ocular lubricants was started. Six months later, the corneal graft had no other complications.

Discussion

When corneal hypoesthesia is present, pathologies affecting trigeminal nerve must be considered. Among them, herpetic keratitis is the most common. Other causes are cerebrovascular accidents, cerebral aneurysms, multiple sclerosis, tumors, diabetes, and congenital diseases.[1] In our patient, thorough systemic examination, laboratory tests and neuroimaging did not reveal an underlying pathology.

This entity can cause sight-threatening complications, such as scarring, neovascularization, or severe necrosis. As a first-line therapy, lubricants and ointments are usually prescribed. Topical autologous serum, RTGA, and amniotic membrane grafting have also shown effectiveness on healing persistent epithelial defects. Patching, tarsorrhaphy, therapeutic contact lenses, and botulinum toxin A-induced ptosis can reduce corneal exposure and prevent corneal surface desiccation. Conjunctival flap should be used only to preserve ocular integrity. The long evolution of this case and the partial effectiveness of the conservative measures reflect how challenging it can be to treat this condition.

S. paucimobilis is a waterborne bacterium that can cause many clinical syndromes. It is considered an opportunistic pathogen. Severe pathology, such as bacteriemia, usually occurs in immunocompromised patients.[2] This microorganism is an infrequent cause of eye infection. To the best of our knowledge, only one case of Sphingomonas paucimobilis keratitis has been previously reported, in a contact lens wearer, who required a tectonic keratoplasty.[3] Endophthalmitis and contamination of transport mediums of corneal grafts have also been reported.[456] We consider that our patient's ocular surface pathology played a key role in corneal 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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.