title: Scleral birefringence as measured by polarization-sensitive optical coherence tomography and ocular biometric parameters of human eyes in vivo.
abstract: The relationship between scleral birefringence and biometric parameters of human eyes in vivo is investigated. Scleral birefringence near the limbus of 21 healthy human eyes was measured using polarization-sensitive optical coherence tomography. Spherical equivalent refractive error, axial eye length, and intraocular pressure (IOP) were measured in all subjects. IOP and scleral birefringence of human eyes in vivo was found to have statistically significant correlations (r = -0.63, P = 0.002). The slope of linear regression was -2.4 × 10(-2) deg/μm/mmHg. Neither spherical equivalent refractive error nor axial eye length had significant correlations with scleral birefringence. To evaluate the direct influence of IOP to scleral birefringence, scleral birefringence of 16 ex vivo porcine eyes was measured under controlled IOP of 5-60 mmHg. In these ex vivo porcine eyes, the mean linear regression slope between controlled IOP and scleral birefringence was -9.9 × 10(-4) deg/μm/mmHg. In addition, porcine scleral collagen fibers were observed with second-harmonic-generation (SHG) microscopy. SHG images of porcine sclera, measured on the external surface at the superior side to the cornea, showed highly aligned collagen fibers parallel to the limbus. In conclusion, scleral birefringence of healthy human eyes was correlated with IOP, indicating that the ultrastructure of scleral collagen was correlated with IOP. It remains to show whether scleral collagen ultrastructure of human eyes is affected by IOP as a long-term effect.
authors.affiliation: Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan ; Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan ; Tomey Corporation, Nagoya, Aichi, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamanari
authors.affiliation: Department of Ophthalmology, Tokyo Medical University Ibaraki Medical Center, Ami, Ibaraki, Japan ; Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Nagase
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan ; Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Fukuda
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan ; Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Ishii
authors.affiliation: Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Tanaka
authors.affiliation: Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan ; Institute of Technology and Science, The University of Tokushima, Tokushima, Tokushima, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yasui
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan ; Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Oshika
authors.affiliation: Department of Ophthalmology, Tokyo Medical University Ibaraki Medical Center, Ami, Ibaraki, Japan ; Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Miura
authors.affiliation: Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan ; Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yasuno
keywords: (050.2555) Form birefringence; (170.4470) Ophthalmology; (170.4500) Optical coherence tomography; (180.4315) Nonlinear microscopy