Understanding the biomechanical behaviour of the cornea is essential for the effective treatment of eye disease and injury, and for predicting the effects of surgery. Earlier efforts to model corneal behaviour have met with limited success due to the overly simplistic idealisation of its material behaviour and geometrical form. As a result, a number of highly precise surgical and clinical techniques still have to rely on empiricism and inaccurate models to predict their outcomes.
This project aims to address these shortfalls by developing computer-based predictive models of the cornea that incorporate more accurate representations of biomechanical behaviour and geometry of the cornea. The models, which will build on experience gained in modelling civil engineering structures, are expected to provide more accurate information on the corneal biomechanical performance to facilitate the development of improved surgical and clinical tools.
Development of Artificial Cornea
This project involves collaboration with the 6th Framework Consortium: 'Three dimensional reconstruction of human corneas by tissue engineering', which funded by the European Union (4.7M Euros) and consists of 14 partner organisations across Europe.
The ultimate aim of the project is to reconstruct a human cornea in vitro, for use both in corneal grafting and as an alternative to animal models for cosmeto-pharmacotoxicity testing. The project responds to the urgent need to develop new forms of corneal replacements as alternatives to the use of donor corneas, in view of of the world-wide shortage of donors, the increasing risk of transmissible diseases, the widespread use of corrective surgery which renders corneas unsuitable for grafting, and the severe limitations of currently available synthetic polymer-based artificial corneas. It also responds to impending EU legislation banning the marketing of cosmetic products that have been tested on animals, using procedures such as the Draize rabbit eye irritation test. The development of tissue engineered corneas will provide a non-animal alternative which will therefore alleviate animal suffering.
Effects of Defective Collagen Ultrastructure on Ocular Biomechanics
Understanding the biomechanical behavior of the cornea is essential in a number of areas of ophthalmology, for example, the effective treatment of corneal disease and injury, the prediction of the effects of surgery and the bioengineering of artificial corneas for grafting. Dr. Newson has been conducting biomechanical testing of corneas and developing computer-based biomechanical predictive models for the cornea for a number of years. These models, which build on experience gained in modelling civil and geotechnical engineering structures, provide understanding of corneal biomechanical performance and facilitate the development of improved surgical, clinical and teaching tools. This study provides insights into the effect of corneal and stromal structure on the biomechanics of normal and diseased cornea and will yield vital information for further development of mathematical models and predictive tools. The ADF grant being requested will help develop an exciting and innovative area of research, which has the potential to benefit patients across North America and internationally.
Novel devices for in situ strength measurement
Offshore pipelines are typically laid on the seabed and lowered into the seabed (trenched) over large sections to provide protection from shipping and fishing activities, or to stabilise the pipeline from hydrodynamic loads. Accurate estimates of the resistance to upward pipeline movement of the overlying clayey trench-backfill are important for design and analytical purposes. The undrained shear strength (cu) of the upper layers of the seabed (particularly the initial 2 to 3 m below the mudline) is therefore a vital part of pipeline site investigations and is commonly found using the cone penetrometer (CPT). The limitations of standard CPTs may be overcome with the use of novel shaped penetrometers. The measured resistance can be easily used to calculate undrained shear strength using an unique bearing capacity or ‘bar’ factor. This paper describes the application of standard in situ cone penetrometer and T-bar tests from an ROV for the determination of undrained shear strength parameters for pipeline buried in deltaic soft clay. Comparisons with in situ plate bearing tests are also provided and the advantages of this novel form of in situ test are discussed. [Read More]
Thermal conductivity of offshore soils
This paper describes thermal conductivity tests conducted on highly disturbed (fluidised) deepwater offshore North Sea clay sediment. The variation of thermal conductivity with moisture content was determined using a specially designed one-dimensional consolidation apparatus. Comparisons were made with results from undisturbed in situ soil cores. The results show very similar values of thermal conductivity for both the undisturbed and fluidised samples for given moisture contents. These values are comparable with results found for similar materials in the North Sea and Gulf of Mexico, but are lower than values typically assumed in current design approaches. [Read More]
Novel anchor systems for offshore use
Since many remotely operated vehicles (ROVs) are neutrally or positively bouyant, any activities that require any significant reaction load, e.g. in situ soil testing, are not possible without additional anchoring or clump weights. Whilst the majority of ROVs used by the offshore oil and gas industries have the necessary hydraulic and pneumatic control systems to employ anchors, previous attempts to develop seabed fixity have had variable success. These include standard anchor systems, such as helical screw, suction, duckbill and plate anchors. Any viable alternative must provide a cheap and reusable system that will provide sufficient pullout capacity and be able to operate in the demanding deep offshore environment.
This project had the aim of determining whether a flexible, inflatable anchor system may provide sufficient uplift capacity to fix ROVs during offshore activities. A series of physical model tests have been used to assess the performance of the proposed anchor system in terms of pullout capacity and mobilisation distance. A limited range of anchor designs and operating conditions were investigated to provide data for this assessment. This paper describes the experimental methodology, anchor system and the testing of the system using an artificial clayey soil. [Read More]
- Corneal thinning diseases (e.g. Keratoconus)
- Indentor techniques for diagnosis of ocular diseases Fundamental stress-strain modelling of corneal tissue response
- Fundamental stress-strain modelling of corneal tissue response
- Glaucoma and the Optic Nerve Head
- Arching around buried culverts
- Wave induced liquefaction of marine soils
- Consolidation of soft soils
- Bearing capacity of crusted clayey soils and mine wastes
- The mechanics of gassy offshore soils
- Upheaval buckling of buried offshore pipelines