A Sideways Look at the Lens

 

In addition to his visiting academic appointment at the School of Optometry and Vision Science, Prof. Arthur Ho (Brien Holden Vision Institute) is a Voluntary Professor of Ophthalmology at the Miller School of Medicine, University of Miami.  Spotlight on Our Research recently spoke with him about one of their latest publications.

SoOR: What is this paper about?

Arthur: What we report on is a system that can measure the 3D shape and the optics of the crystalline lens. That’s the lens inside our eyes that makes it possible to change focus and see up close (a function called “accommodation”). The team achieved this by combining several key pieces of technology: a 3D OCT for imaging the lens shape, ray-tracing aberrometry for the optics and a mechanical lens stretcher that can effect a change in the lens focus in a near-physiological manner.

SoOR: Quite a unique system then?

Arthur: We believe this is the only such system in the world. A key feature is that we can measure the optics of the lens not just from front on, but from different directions. This enables us to characterise the lens in a way that was not achievable previously. Our system can tell us how the lens focuses light that enters the eye from side-on, that is, our peripheral vision.

SoOR: What was the motivation that led to this work?

Arthur: This paper is the latest instalment of developments over many decades of research by the group at the University of Miami. The mission is to understand the optics and mechanics of accommodation; for example, to understand why older individuals need reading glasses and how we can optimise their vision. The OCT, the laser ray-tracing system, and the lens stretcher were all specifically developed towards that quest.

SoOR: You sound quite excited about this work.

Arthur: Definitely.  I am most fortunate to have been working with the Miami group for over twenty-five years. The scientists and engineers, such as Dr Ruggeri and Prof. Manns; the ‘brains’ behind the system, under the direction of Prof. Parel at the Ophthalmic Biophysics Center, have made so many outstanding scientific contributions over the years. With this system, we hope to learn a lot more about what happens when the lens changes focus to enable the eye to see up close.

SoOR: So this technology will tell us more about accommodation and presbyopia?

Arthur: There is also an exciting potential relevance to understanding myopia development. Some studies into myopia implicate image quality, accommodation and peripheral refraction as possible factors in influencing myopia progression. Combine that with the typical age of onset of child myopia and the biphasic growth of the lens, which ‘coincidentally’ changes its growth rate at around the same age range, and we may reasonably suspect the crystalline lens could play a role in myopia progression. So being able to characterise central and peripheral optics of the lens using this system might provide some clues to understanding myopia development. Hopefully, we will have more results to present on this in the future.

The article “System for on- and off-axis volumetric OCT imaging and ray tracing aberrometry of the crystalline lens” is published in Vol 9 of Biomedical Optics Express.

3D OCT image of a human crystalline lens (image courtesy of Dr Marco Ruggeri, University of Miami).