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2023 OMIG Abstract

Histopathologic Correlation Between Acanthamoeba Species Recovered from Patients Who Underwent Therapeutic and Optical Penetrating Keratoplasties After Rose Bengal Photodynamic Antimicrobial Therapy

Jaime D. Martinez¹, Jordan Huang^1,5, Juan Carlos Navia^1,2, Matthew Camacho⁴, Sara Mustafa¹,
Paula A. Sepulveda-Beltran¹, Guillermo Amescua¹, Darlene Miller³, Sander Dubovy^1,4, Jean-Marie Parel<sup>2

1</sup>Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL; ²Ophthalmic Biophysics Center, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL; ³Ocular Microbiology Laboratory, Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL; ⁴Florida Lions Ocular Pathology Laboratory, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL; ⁵University of Calgary Cumming School of Medicine, Calgary, Alberta, Canada

Purpose: To compare the microbiologic and histopathologic features of Acanthamoeba isolates recovered from patients who underwent Therapeutic Penetrating Keratoplasties (TPK), Optical Penetrating Keratoplasties (OPK), and Deep Anterior Lamellar Keratoplasties (DALK) after adjunct treatment with Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT).

Methods: Retrospective review of patients diagnosed with Acanthamoeba keratitis at the Bascom Palmer Eye Institute between August 2016 and August 2022, that underwent TPKs and OPKs after RB-PDAT. A total of 17 patients with Acanthamoeba keratitis that received RB-PDAT were included in this study. Host corneas were analyzed after keratoplasty for acanthamoeba cyst depth, number of cysts, and average corneal thickness.

Results: 17 eyes of 17 patients were included (43.7±19.9 years old; 70.5% female). Mean follow-up time was 30.3±15 months. Of those, 8 patients (47.0%) required TPKs, and 9 (52.9%) underwent OPKs/DALKs. Of the 8 patients that underwent TPK, 6 patients were positive for cysts on cornea tissue pathology analysis. Amongst these patients, the average acanthamoeba cyst depth from Descemet's layer was 42.0±52.5µm. The average number of grading cysts was 1.3±0.7. The average corneal button thickness was 661.7±106.5µm. The rate of reinfection after TPK was 12.5% (1/8 patients). Comparatively, of the 9 patients that underwent OPK/DALK, 3 patients were positive for cysts on corneal tissue pathology analysis. Amongst the 3 patients, average acanthamoeba cyst depth from Descemet's layer was 261.7±222.7µm. The average number of grading cysts was 1.3±0.9. The average corneal button thickness was 474.2±126.6µm. None of the patients in this group had a reinfection of their cornea after OPK/DALK.

Conclusions: Pathological and microbiological analysis of host corneal tissue harvested from patients who underwent RB-PDT for acanthamoeba infections revealed deeper cyst depth in the cornea in patients undergoing TPK compared to OPK/DALK. Deeper penetration of the infectious acanthamoeba cyst into the cornea may be a critical factor to explain the increased resistance to standard medical treatment and subsequent RB-PDT treatment failure observed.

Disclosure: N

Support: Edward D. and Janet K. Robson Foundation, Florida Lions Eye Bank and the Beauty of Sight Foundation (Olsen, Hildebrant, Urs, and Furtado; NIH Center Grant P30EY14801, Research to Prevent Blindness, Henri and Flore Lesieur Foundation (Parel)

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