Primary Amniotic Membrane Transplantation for Sterile Corneal Ulcer leading to hypopyon: Rare case

The purpose of case report by Kostas G. Boboridis and team was to present the acute development of sterile hypopyon into the anterior chamber following primary cryopreserved AMT onto the corneal surface for persistent sterile corneal epithelium defect and stromal thinning.

Case Presentation

A 71-year-old male patient with a persistent central corneal epithelial defect and stromal thinning of 5 mm diameter on his right eye with no evidence of infection or corneal neuropathy was intermittently responsive to conservative topical treatment with antibiotic drops and ointment, intensive lubricating drops, and bandage contact lenses.

The central cornea had a thinner area of 2 mm diameter with only 1/3 of the stroma remaining before Descemet's membrane and showed no sign of healing with only intermittent epithelialization despite the conservative treatment for over eight weeks from presentation.

There was no evidence of corneal hypesthesia, and repeated corneal swabs for microbiology investigation proved the sterility of the lesion. The clinical suspicion of corneal rubbing against the pillow because of his sleeping preference on his right side was the most probable cause of his condition.

As counselling for his sleep pattern and conservative lubricating treatment had no effect, surgeons proceeded with surgical management of his corneal defect using cryopreserved AM. The routine postoperative regimen was combined steroid and antibiotic eye drops 6 times daily for two weeks tapering down thereafter.

For deep corneal ulceration, surgeons used small pieces of AM to fill the stroma defect placed as grafts with epithelial side up aiming at subepithelial or transepithelial integration of the membrane in relation to the newly formed epithelium. Following limbal peritomy, a large piece of AM is placed as a patch with the epithelial side down covering the entire cornea and limbal area, aiming at superficial localization (disintegration) of this covering piece of amniotic membrane.

In theory, this arrangement will facilitate the growth of a new, healthy corneal epithelium from the intact limbal area under the superficial layer of AM but over the small pieces of AM covering the stroma defect.

The AM graft was prepared and cryopreserved by local eye bank using the Good Tissue Banking Practice procedures. Despite the tested sterility of the ocular surface, the preoperative antibiotic treatment, and the uneventful perioperative period, he developed a 2 mm hypopyon within 48 hours when reviewed him after primary AMT. He was using the routine regimen of tobramycin 3 mg/ml and dexamethasone 1 mg/ml eye drops six times daily on a fixed combination.

Despite the alarming clinical presentation, there were no anterior chamber reaction and no signs of active infection; therefore, the authors considered the hypopyon formation being a sterile toxic or immunologic reaction.

To confirm this diagnosis, a surface swab was taken from the membrane and performed a full microbiological examination of the residual membrane and its culture medium which were proven negative.

The patient continued with their standard post-AMT treatment with increased dosage every two hours for three days, followed by 6 times daily for two more weeks tapering down thereafter. The hypopyon resolved completely with the current treatment a week later with no further complications or anterior chamber reaction. The epithelial defect and corneal thinning healed satisfactorily with smooth epithelium and a visible stromal scar with no recurrence or hypopyon 5 weeks postoperatively.

Infection and toxic or immunologic reaction are the three most possible pathophysiological mechanisms for hypopyon formation in the immediate postoperative period following AMT. Neurotrophic keratopathy which is often requires AMT can present hypopyon in the natural course of the disease, but this case had uncompromised corneal sensation.

The presented case developed sterile hypopyon within two days after primary cryopreserved AMT for sterile corneal ulceration with no prior immunological sensitization or other ocular surface disease and resolved with our routine topical treatment for AMT.

This report highlights the fact that cryopreserved amniotic membrane, although immunologically inert, when transplanted onto the corneal surface may elicit a localized sterile immune reaction presenting with a transient hypopyon formation.

There is a strong need for more investigations into the immunologic implications of AMT and possible complications related to AMT. The uncommon complication of hypopyon formation soon after AMT should be clearly differentiated from surface infection or even endophthalmitis and treated accordingly.

Source: Hindawi Case Reports in Ophthalmological Medicine; Volume 2021, Article ID 9982354, 5 pages

https://doi.org/10.1155/2021/9982354