title: Intraocular Pressure Induced Retinal Changes Identified Using Synchrotron Infrared Microscopy.
abstract: Infrared (IR) spectroscopy has been used to quantify chemical and structural characteristics of a wide range of materials including biological tissues. In this study, we examined spatial changes in the chemical characteristics of rat retina in response to intraocular pressure (IOP) elevation using synchrotron infrared microscopy (SIRM), a non-destructive imaging approach. IOP elevation was induced by placing a suture around the eye of anaesthetised rats. Retinal sections were collected onto transparent CaF2 slides 10 days following IOP elevation. Using combined SIRM spectra and chemical mapping approaches it was possible to quantify IOP induced changes in protein conformation and chemical distribution in various layers of the rat retina. We showed that 10 days following IOP elevation there was an increase in lipid and protein levels in the inner nuclear layer (INL) and ganglion cell layer (GCL). IOP elevation also resulted in an increase in nucleic acids in the INL. Analysis of SIRM spectra revealed a shift in amide peaks to lower vibrational frequencies with a more prominent second shoulder, which is consistent with the presence of cell death in specific layers of the retina. These changes were more substantial in the INL and GCL layers compared with those occurring in the outer nuclear layer. These outcomes demonstrate the utility of SIRM to quantify the effect of IOP elevation on specific layers of the retina. Thus SIRM may be a useful tool for the study of localised tissue changes in glaucoma and other eye diseases.
authors.affiliation: Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria, Australia.|Infection and Immunity Program, Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
authors.forename: Hsin-Hui
authors.initials: HH
authors.lastname: Shen
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia.|Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia.
authors.forename: Guei-Sheung
authors.initials: GS
authors.lastname: Liu
authors.affiliation: Infection and Immunity Program, Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
authors.forename: Seong Hoong
authors.initials: SH
authors.lastname: Chow
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia.|Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia.
authors.forename: Jiang-Hui
authors.initials: JH
authors.lastname: Wang
authors.affiliation: Department of Optometry & Vision Sciences, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Zheng
authors.initials: Z
authors.lastname: He
authors.affiliation: Department of Optometry & Vision Sciences, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Christine
authors.initials: C
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry, Tunghai University, Taichung City, Taiwan.
authors.forename: Tsung-Wu
authors.initials: TW
authors.lastname: Lin
authors.affiliation: Department of Optometry & Vision Sciences, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Bang V
authors.initials: BV
authors.lastname: Bui
mesh_terms: D000818:Animals; D007259:Infrared Rays; D007429:Intraocular Pressure; D008853:Microscopy / Q000295:instrumentation*; D011487:Protein Conformation; D051381:Rats; D012160:Retina / Q000378:metabolism / Q000502:physiology*; D017356:Synchrotrons