Vision & Biophotonics Laboratory
Research Team
- Dr Andrew Metha
- Dr Shelly Ames
- Associate Professor George Smith
- Mr Philip Bedggood
- Mr Rajeev Narayanan
- Mr Alaster Meehan
National & International Collaborators
- Dr Shaban Demirel - Devers Eye Institute, Portland, USA
- Professor David Atchison - Optometry, Queensland University of Technology, Australia
- Professor Keith Nugent - School of Physics, The University of Melbourne
- Dr Brendan Allman
The broad aim of the Vision and Biophotonics Laboratory is to bridge our everyday perceptual experience of seeing to knowledge of the optical and neural elements comprising the visual system from the tear film to brain. Work in the VBL tackles this fundamental endeavour from different but complementary angles:
- precise measurement of optical parameters of the eye using wavefront aberrometry and adaptive optics
- high resolution imaging of the retinal fundus
- measurement of visual performance in psychophysical studies
- computational modelling of optical and perceptual performance
- consulting services
Current Projects Available in the Vision & Biophotonics Laboratory (among others)
Adaptive Optics & The Eye
Work in the VBL investigates the potential for multiple flexible mirrors to be used to 1) improve our understanding of how different ocular components individually contribute to overall aberration, and 2) to increase the isoplantic zone in retinal images so as to maintain high lateral resolution while extending the field of view of retinal ophthalmoscopy. Using optical modeling software, our techniques are based on adaptive optics, where a deformable mirror is used to cancel out the distorting aberrations inherent in real and model eyes. Multi-conjugate adaptive optics describes the field of science that uses not one, but several deformable mirrors to extend the spatial extent of the well-corrected imaging plane. Improved knowledge about how aberrations are created by different ocular surfaces will yield clinical benefits including better prediction of outcomes in cases of intraocular lens extraction.
Performance Limitations Imposed by Ocular Optics
The optical properties of the eye are said not to be perfect, but a full characterization of the eye's imperfections (aberrations) has not in general been made. Importantly, neither has the impact of these imperfections on actual visual performance been described - it could be that some aberrations can promote rather than detract from visual performance. Two aberrations in particular require intense study, and both theoretical (computer modeling) and psychophysical projects exist to determine: i) the extent to which spherical aberration can be considered an effective means of apodization to ameliorate the spurious high spatial frequencies injected into the retinal image upon defocus, and ii) the extent to which the chromatic aberrations (longitudinal and lateral) can inform the retina about relative sign of retinal defocus (relative myopia or hyperopia).
Selected Recent Publications
- Tailby, C., Solomon, S.G., Peirce, J.W., & Metha, A.B. (2007). Two expressions of "surround suppression" in V1 that arise independent of cortical mechanisms of suppression. Vis Neurosci, 24 (1), 99-109.
- Vallam, K., & Metha, A.B. (2007). Spatial structure of the frequency doubling illusion. Vision Res, 47 (13), 1732-1744.
- Vallam, K., & Metha, A.B. (2007). The relationship between temporal phase discrimination ability and the frequency doubling illusion. J Vis, 7 (14), 17 11-11.
- Vallam, K., Pataridis, I., & Metha, A.B. (2007). Frequency-doubling illusion under scotopic illumination and in peripheral vision. Invest Ophthalmol Vis Sci, 48 (7), 3413-3418.
- Bedggood, P., Smith, G., Ashman, R., & Metha, A. (2006). Multiconjugate adaptive optics applied to an anatomically accurate human eye model. Optics Express, 14 (18), 8019-8030.
- Daaboul, M., Ashman, R., Bedggood, P., Buzas, P., Martin, P., Grunert, U., Smith, G., & Metha, A. (2005). Wave aberrations and imaging potential of the anesthetized and paralyzed marmoset eye. Australian Ophthalmic and Visual Sciences Meeting (pp. 30 (Poster 31-13)). The University of Melbourne, 3 December 2005: The Australian Society for Visual Research.
- Smith, G., Bedggood, P., Ashman, R., & Metha, A. (2005). Multi-conjugate adaptive optics for ocular aberration correction. 11th Scientific Meeting in Optometry, Queensland University of Technology, September 27-28.
- Ashman, R., Daaboul, M., Atchison, D.A., Smith, G., & Metha, A. (2004). Effects of torsion on ocular aberrations. OWLS 8 - The 8th International Conference on Optics Within Life Sciences: "Biophotonics Down Under" (Melbourne Australia - Nov 28 - Dec 1, 2004 - http://swin.edu.au/optics/cmp/owls8)
- Metha, A.B., & Lennie, P. (2001). Transmission of spatial information in S-cone pathways. Vis Neurosci, 18 (6), 961-972.
- Roorda, A., Metha, A.B., Lennie, P., & Williams, D.R. (2001). Packing arrangement of the three cone classes in primate retina. Vision Reseach, 41 (10-11), 1291-1306.