Intraocular Pressure Induced Retinal Changes Identified Using Synchrotron Infrared Microscopy

Hsin-Hui Shen; Guei-Sheung Liu; Seong Hoong Chow; Jiang-Hui Wang; Zheng He; Christine Nguyen; Tsung-Wu Lin; Bang V Bui

doi:10.1371/journal.pone.0164035

Intraocular Pressure Induced Retinal Changes Identified Using Synchrotron Infrared Microscopy

PLoS One. 2016 Oct 6;11(10):e0164035. doi: 10.1371/journal.pone.0164035. eCollection 2016.

Authors

Hsin-Hui Shen^{1

2}, Guei-Sheung Liu^{3

4}, Seong Hoong Chow², Jiang-Hui Wang^{3

4}, Zheng He⁵, Christine Nguyen⁵, Tsung-Wu Lin⁶, Bang V Bui⁵

Affiliations

¹ Department of Materials Science and Engineering, Faculty of Engineering, Monash University, Clayton, Victoria, Australia.
² Infection and Immunity Program, Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
³ Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia.
⁴ Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia.
⁵ Department of Optometry & Vision Sciences, University of Melbourne, Parkville, Victoria, Australia.
⁶ Department of Chemistry, Tunghai University, Taichung City, Taiwan.

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.

MeSH terms

Animals
Infrared Rays*
Intraocular Pressure*
Microscopy / instrumentation*
Protein Conformation
Rats
Retina / metabolism
Retina / physiology*
Synchrotrons*

Grants and funding

This work was supported by the National Health and Medical Research Council of Australia (http://www.nhmrc.gov.au/) # 1106798 (HHS) #11081072 (GSL) #1061912 (JHW) NHMRC #1046203 (BVB) #1106798. BVB is supported by an Australian Research Council (www.arc.gov.au/) Future Fellowship (FT130100338). This work was also supported The Centre for Eye Research Australia receives Operational Infrastructure Support from the Victorian Government. (www.vic.gov.au/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.