Dr Jacek Pijanka
Research Topics and Related Projects:
Glaucoma is characterised by a progressive, irreversible damage to the retinal nerve fibres, leading to blindness. A major cause is elevated pressure within the eye (IOP), although vision loss can occur at all IOP-levels. The physical effects of IOP are transmitted to the optic nerve region via the sclera, hence the sclera’s response to IOP is likely to be important in the disease process. Scleral biomechanical properties are conferred to large extent by the complex network of collagen fibres that form the sclera’s major load-carrying component. The sclera’s role in glaucoma is poorly understood, largely because the organisation of this collagen network is not well known.
To quantify scleral collagen we use a powerful technique based on wide-angle x-ray scattering (WAXS). Analysis of the x-ray scatter patterns from the lateral spacing of collagen molecules provides direct, quantitative measure of collagen fibres preferential orientation and distribution, which we have recently used to characterise the whole human eyeball coat (sclera and cornea).
Quantitative maps of collagen orientation and number of preferential fibres (degree of anisotropy) allow comparison between normal and glaucomatous tissues in search of structural differences. Degree of anisotropy data is further analysed statistically; collagen orientation is also validated by second harmonic generation microscopy imagining of the same samples. The x-ray data together with the deformation data obtained by mechanical testing of the same specimens is further used to construct numerical models that calculate the material properties of the sclera and predict its response to IOP. This work enables also investigation of the age-related changes in the tissue structural and material properties.
Figure 1: WAXS analysis of collagen architecture in normal and ADAMTS10-mutant canine posterior sclera.
Figure 2: 2D (top) and 3D maps of collagen fibre preferential orientation in the human posterior sclera
Boote C (PI) & Meek KM, £122,672, Project Grant FFS1360: "The role of the sclera in human glaucoma", Fight For Sight, 2012-2014.
Dr Harry Quigley, Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine.
Prof. Thao Nguyen, Department of Mechanical Engineering, Johns Hopkins University.
Prof. Ahmed Elsheikh, School of Engineering, University of Liverpool.
Prof. Jum Liu, Department of Biomedical Engineering, The Ohio State University