title: Comparison of reflectance confocal microscopy and two-photon second harmonic generation microscopy in fungal keratitis rabbit model ex vivo.
abstract: Fungal keratitis is an infection of the cornea by fungal pathogens. Diagnosis methods based on optical microscopy could be beneficial over the conventional microbiology method by allowing rapid and non-invasive examination. Reflectance confocal microscopy (RCM) and two-photon second harmonic generation microscopy (TPSHGM) have been applied to pre-clinical or clinical studies of fungal keratitis. In this report, RCM and TPSHGM were characterized and compared in the imaging of a fungal keratitis rabbit model ex vivo. Fungal infection was induced by using two strains of fungi: aspergillus fumigatus and candida albicans. The infected corneas were imaged in fresh condition by both modalities sequentially and their images were analyzed. Both RCM and TPSHGM could detect both fungal strains within the cornea based on morphology: aspergillus fumigatus had distinctive filamentous structures, and candida albicans had round structures superficially and elongated structures in the corneal stroma. These imaging results were confirmed by histology. Comparison between RCM and TPSHGM showed several characteristics. Although RCM and TPSHGM images had good correlation each other, their images were slightly different due to difference in contrast mechanism. RCM had relatively low image contrast with the infected turbid corneas due to high background signal. TPSHGM visualized cells and collagen in the cornea clearly compared to RCM, but used higher laser power to compensate low autofluorescence. Since these two modalities provide complementary information, combination of RCM and TPSHGM would be useful for fungal keratitis detection by compensating their weaknesses each other.
authors.affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, South Korea.
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, South Korea.
authors.forename: Seunghun
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, South Korea.
authors.forename: Calvin J
authors.initials: CJ
authors.lastname: Yoon
authors.affiliation: Department Department of Ophthalmology, University of Ulsan College of Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro, 43-gil, Songpa-gu, Seoul, 05535, South Korea.
authors.forename: Jin Hyoung
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department Department of Ophthalmology, University of Ulsan College of Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro, 43-gil, Songpa-gu, Seoul, 05535, South Korea.
authors.forename: Hungwon
authors.initials: H
authors.lastname: Tchah
authors.affiliation: Department Department of Ophthalmology, University of Ulsan College of Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro, 43-gil, Songpa-gu, Seoul, 05535, South Korea; joon@amc.seoul.kr.
authors.forename: Myoung Joon
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Mechanical Engineering, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, South Korea; Department of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, South Korea; kiheankim@postech.edu.
authors.forename: Ki Hean
authors.initials: KH
authors.lastname: Kim
keywords: (170.0170) Medical optics and biotechnology; (170.1790) Confocal microscopy; (170.2520) Fluorescence microscopy; (170.4470) Ophthalmology