The Liverpool View: Engineering and the human eye

eyegraphic-1wDr Riaz Akhtar is a lecturer in Biomedical Engineering in the University of Liverpool’s School of Engineering

“When people think about biomechanics research, they will typically think of study related to some aspect of the human musculoskeletal system such as treating knee injuries or osteoarthritis. However, the eye is rarely associated with biomechanics by the lay person.

Nothing could be further from the truth as ocular biomechanics research is opening up the possibility of treating many serious and common eye conditions.

Solid and fluid mechanics

The eye is actually a pressurised vessel and many physiological and pathological processes within the eye can be understood with the application of principles from solid and fluid mechanics. Common eye disorders such as glaucoma and myopia (near-sightedness) are associated with profound biomechanical changes.

It is for this reason that the biomechanics community has devoted more attention to addressing important research questions in ophthalmology in recent years.

One of my research interests in ocular biomechanics is in keratoconus, which is a progressive, degenerative disease that is now considered to be a major clinical problem worldwide. An article published in Scientific Reports earlier this year reports that keratoconus affects 4 to 600 per 100,000 people. Although this may be considered to be relatively rare, the condition seems to be on the rise. 

”My brother and I have recently been diagnosed with a mild form of the disease. Hence, both academic endeavour and personal desire are motivating factors for my research in this area”
The pathophysiology of keratoconus poses important biomechanical questions because the cornea becomes thinner, cone-shaped and is characterised by mechanical weakness.

Aside from academic interest a better understanding of, and the development of improved treatment methods for the condition is a personal quest for me also.

My brother and I have recently been diagnosed with a mild form of the disease. Hence, both academic endeavour and personal desire are motivating factors for my research in this area. I was recently involved in a study which focussed on measuring mechanical changes that can be induced in the cornea with an exciting and relatively new clinical procedure for keratoconus which involves the use of riboflavin (vitamin B2) and ultraviolet-A (UVA) light irradiation to halt progression of the disease.

The cornea is composed of a regular matrix of collagen fibres which provide mechanical support. These collagen fibres are strengthened by inter-molecular bonds or cross-links. In keratoconus, it is thought that these cross-links are abnormal and reduced, resulting in the bulging shape of the cornea and associated thinning and mechanical weakness.

”I am privileged to be part of an excellent network of researchers, which crosses traditional discipline and faculty boundaries. Our research group in the School of Engineering, together with the Department of Eye and Vision Sciences, brings together experts with different backgrounds and complementary skills”
The new crosslinking procedure aims to induce additional cross-links in the cornea. This procedure not only increases the stiffness and strength of the cornea but has an additional benefit as it is found to flatten the cornea and thereby reduce myopia and astigmatism. There are still many unanswered questions regarding this procedure that we hope to tackle in future research.

I am also interested in increasing our understanding of the structure and properties of the sclera, or white of the eye. The sclera is not just an inert casing that holds the eye together, it also has an important biomechanical role in healthy eye function.

Myopics are found to have a weaker and elongated sclera. Relative to the cornea, the sclera has a much more complicated structure and is less extensively studied. Again, there are many unanswered questions which we hope to address in sclera biomechanics.

I am privileged to be part of an excellent network of researchers, which crosses traditional discipline and faculty boundaries. Our research group in the School of Engineering (www.ocular-biomechanics.liv.ac.uk), together with the Department of Eye and Vision Sciences, brings together experts with different backgrounds and complementary skills including clinicians, materials scientists, structural engineers, image processers and mathematical modellers.

Our group in Engineering is led by Professor Ahmed Elsheikh who, over the last decade, has led the development of innovative experimental techniques to determine the mechanical behaviour of the eye, and medical devices to improve the management and treatment of a number of ocular conditions.

Inter-disciplinary collaborations

We are working closely with Professor Rachel Williams who is the Group Leader for Bioengineering, imaging technology and informatics in the Department of Eye and Vision Sciences. Professor Williams has pioneered the development of new ocular biomaterials, and by establishing a number of inter-disciplinary collaborations is helping to build a hub of excellence in ophthalmic bioengineering at Liverpool.

This coupling of one of the largest ocular biomechanics research groups in the UK with pioneers in ocular bioengineering means that Liverpool has the perfect ingredients for tackling challenging ocular pathologies as we cover the entire spectrum – from basic science to ophthalmology practice.”

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