RT Journal Article A1 Martinez, Jaime D. A1 Dubovy, Sander R A1 Amescua, Guillermo A1 Monsalve, Pedro A1 Zhou, Xiao Yi A1 Arboleda, Alejandro A1 Durkee, Heather Ann A1 Aguilar, Mariela C A1 Relhan, Nidhi A1 Nikpoor, Neda A1 Flynn, Harry W A1 Miller, Darlene A1 Parel, Jean-Marie A T1 Corneal Changes in Patients Treated with Rose Bengal Photodynamic Antimicrobial Therapy for Severe Infectious Keratitis JF Investigative Ophthalmology & Visual Science JO Invest. Ophthalmol. Vis. Sci. YR 2018 VO 59 IS 9 SP 529 OP 529 SN 1552-5783 AB To describe corneal changes in patients who were treated with rose bengal photodynamic antimicrobial therapy (PDAT) as an adjunct treatment for infectious keratitis (Amescua et al. Cornea. 2017 Sep;36(9):1141-1144). Corneal tissue histopathology was examined on four patients who underwent rose bengal PDAT as an adjunct treatment for infectious keratitis and subsequent optical corneal graft once the infection and inflammation resolved. Corneal thickness was measured on histology sections. Corneal tissue histopathology findings were correlated with slit-lamp and Anterior Segment Optical Coherence Tomography (AS-OCT) images taken pre- and post- rose bengal PDAT. In all cases, corneal tissue histopathology showed a demarcation line on the stromal tissue ranging from 30 to 220 µm from the epithelium. Total corneal tissue mean thickness was 682 µm (range 450 to 940±177.2). In two cases, alpha smooth muscle actin antibody was negative, and in the other two cases had partial positive stromal staining. In one case a clear demarcation line is present post- rose bengal PDAT on both narrow beam slit-lamp and AS-OCT images, at a depth of 220 and 210 µm, respectively. Corneal tissue histopathology provides information about the wound healing respons to rose bengal PDAT that will be useful in understanding effect of this novel treatment. Corneal stromal demarcation line may be useful in determining the depth of rose bengal PDAT which may help guide future treatments for different stages of progressive infectious keratitis. This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018. Cornea changes of Case 1 visualized with slit-lamp, histopathology, and AS-OCT. Narrow beam slit-lamp images of (a) pre-and (b) post-rose bengal PDAT showing demarcation line (arrows). (c) Histopathology showing changes in the anterior corneal stroma above the demarcation line (arrows). (d) AS-OCT images showing demarcation line (arrows) post-rose bengal PDAT. RD 4/17/2021