Management Of Recurrent Acanthamoeba Keratitis Following Penetrating Keratoplasty

Acanthamoeba keratitis (AK) is a rare but severe ocular infection with a significant risk of vision loss. Disease severity and the time from symptom onset to diagnosis can predict the duration of treatment, final visual outcomes, and the eventual need for surgery. Therapeutic penetrating keratoplasty(TPK) is a treatment option for severe AK, although Acanthamoeba infection may relapse, and the visual prognosis is guarded. Recurrence of AK after penetrating keratoplasty may occur even several months after the operation and the manifestation may be atypical. The purpose of this clinical case is to present new approaches to the treatment of severe, recurrent or medication-resistant corneal infections.

The study took place at The S. Fyodorov Eye Microsurgery Federal State Institution including the one year follow-up.

A 32-year-old female admitted with a 6 month history of pain, tearing, and gradual vision loss in her left eye. She had used contact lenses for myopia correction for 9 years. She noted redness of her left eye after taking shower in the gym bathroom. The condition of the eye worsened within two months. She  was diagnosed with a corneal ulcer at the local hospital. After unsuccessful medical treatment, she underwent photherapeutic keratectomy, which also proved unsuccessful. Slit-lamp examination revealed a stromal corneal infiltrate measuring 2 × 3 mm with fluorescent staining. The amoebic etiology of ulcer was confirmed by confocal microscopy. The accessible areas of affected tissue were removed under the intraoperative OCT control and Corneal cross-linking (CXL) was carried out. The patient noted improvement. However, after two weeks, confocal microscopy revealed amoebic cysts in all layers of cornea. A decision was made to perform a TPK. Despite the medical treatment, after two months amoebic cysts were found in a corneal graft. A decision was made to carry out CXL in a corneal graft. To evaluate the anti-inflammatory properties of CXL, we developed a new photosensitizer formulation, that contains of riboflavin and silver nanoparticles. The absence of amoebic cysts was confirmed by confocal microscopy. There was no recurrence of AK during the 8-month follow-up. The corneal graft is transparent.
The patient noted improvement in condition and vision (0.7).

The use of confocal microscopy is important not only for diagnosis of initial infection, but also for assessing each stage of treatment.The use of photosensitizer based on riboflavin and silver nanoparticles for CXL is proving to be effective in stabilization and treatment of severe, recurrent and medication-resistant corneal infections.This kind of modification can be used as a monotherapy for superficial lesions or as a part of combined therapy to stabilize the inflammatory process and prepare the eye for more radical methods of surgical treatment.