Retinal Reflectometry and Imaging

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Retinal Reflectometry is a technique that uses the light returning from the retina, through the pupil (generally), to infer the properties and functions of the retina.   In a sense all retinal imaging is a form of retinal reflectometry, but I restrict the term to cases where we use the actual quantitative amount of light returning to make inferences.   I have collaborated extensively with both Ann Elsner and Francois Delori for reflectometric measurements, and as such, some of the work I mention here actually comes from their labs.  We have sections on photoreceptor alignment reflectometry, polarization, lens and macular pigment, and retinal imaging.

Representative Publications:

• Elsner, AE, Burns SA, Weiter JJ, and Delori, FC "Infra-red imaging of subretinal structures" Vision Research 36,191-205,1996 
• Delori, FC, and Burns SA. "Fundus reflectance and the measurement of crystalline lens density" J. Opt. Soc. Amer. A. 13,215-226, 1996. 
• Burns, SA, Wu, S, He, J, and Elsner, AE “Variations in photoreceptor directionality across the central retina”, J. Optical Society Amer, A 14, 2033-2040, 1997. PMCID: PMC3395223
• Marcos, S, Burns, SA, and He, J "A Model for cone directionality reflectometric measurements based on scattering." Journal of the Optical Society of AmericaA 15, 2012-2022, 1998.

Just as the Stiles Crawford effect (the variation in sensitivity of the eye depending on the angle light hits the retina) reveals the orientation of the cones, so does the reflection of light from the retina.  We used this phenomenon to study cone alignment and variations in alignment.

Publications

• Burns, SA, Wu, S., Delori, F. and Elsner AE "Direct Measurement of Human Cone Photoreceptor Alignment" J. Opt. Soc. Amer. A. 12, 2329-2338, 1995. 
• Elsner, AE, Burns, SA, Beausencourt, E, and Weiter, JJ, "Foveal cone photopigment distribution: small alterations associated with macular pigment distributions", Invest. Ophthalmol. Vis. Sci. 39,2394-2404 1998
• Marcos, S, and Burns, S.A.“Cone spacing and waveguide properties from cone directionality measurements” J. Opt. Soc. Amer. A 16, 995-1004, 1999. PMCID: PMC2882181 
• He, JC, Burns,  S.A., and Marcos, S. “Comparison of cone directionality determined by psychophysical and reflectometric techniques” Journal of the Optical Society, A, 16:2363-2369, 1999. PMC2970515
• Elsner AE, L. Moraes, E. Beausencourt, A. Remky, S.A. Burns, J.J. Weiter, J. P. Walker, G. L. Wing, P. A. Raskauskas and L. M. Kelley “Scanning laser reflectometry of retinal and subretinal tissues” Optics Express 6, 243-250, 2000.
• Elsner,A.E., Miura, M., Burns, S.A., Beausencourt. E, Kunze C.,Kelley, L.M., Walker, J.P., Wing G. Raskauskas P.A., D.C. Fletcher D.C., Zhou Q. and Dreher A. “Multiply scattered light tomography and confocal imaging: detecting neovascularization in age-related macular degeneration” Optics Express 7, 95-106, 2000.
• Delori, F. C., D. G. Goger, B. R. Hammond, D. M. Snodderly and S. A. Burns (2001). "Macular pigment density measured by autofluorescence spectrometry: comparison with reflectometry and heterochromatic flicker photometry." J Opt Soc Am A Opt Image Sci Vis18(6): 1212-30. 2001
• Ferguson, RD. Hammer, DX, Elsner, AE, Webb, RH, Burns, SA, Weiter, JJ. Wide-field retinal hemodynamic imaging with the tracking scanning laser ophthalmoscope. Optics Express, 12, 5198-5208, 2004. PMC2923468
• Prieto, P, McLellan, J.S., and Burns, S.A. Investigating The Light Absorption In A Single Pass Through The Photoreceptor Layer By Means Of The Lipofuscin Fluorescence. Vision Research 45 (15): 1957-1965, 2005, PMCID: PMC1479308
• Marcos, S, and Burns, SA, Cone Directionality from Laser Ray Tracing in Normals and LASIK patients, Journal of Modern Optics. 56: 2181 – 2188 2009

We have used polarization as both a way to probe and separate components of the retinal light return and as a way to extract extra information from the retina.   Thus, we have shown using photoreceptor alignment reflectometry (PAR) that the cone component of light returning from the retina is highly polarization preserving.   As such in imaging, you can use a form of polarization imaging to look at only multiply scattered light (the depolarized light) and improve visibility of drusen and other subretinal structured.  To do this we used custom approaches to analyze data from a GdX retinal imaging system.   This same analysis also allows separation of components that are birefringent, revealing the pattern of Henle fiber layers, even in eyes with atrophy.   By applying this to AO imaging we also showed an improvement of cone contrast.

Publications

• Burns, SA, Wu, S., Delori, F. and Elsner AE "Direct Measurement of Human Cone Photoreceptor Alignment" J. Opt. Soc. Amer. A. 12, 2329-2338, 1995. 
• Prieto, P.M., Vargas-Martín,F, McLellan, JS, and Burns, SA, “The effect of the polarization on ocular wave aberration measurements”. J Opt Soc Am A Opt Image Sci Vis 19: 809-814, 2002.m PMID: 11934175
• Burns, SA, Elsner, AE, Mellem-Kiraila, MB, and Simmons, RB, Improved Contrast of Subretinal Structures using Polarization Analysis, Invest Ophthalmol Vis Sci 44(9): 4061-8., 2003, PMCID: PMC2748276
• Mellem-Kairala, MB, Elsner,AE, Weber, A, Simmons,RB, Burns, SA, "Improved contrast of peripapillary hyperpigmentation using polarization analysis." Investigative Ophthalmology & Visual Science 46(3): 1099-1106, 2005, PMID: 15728571 
• Song, H, Zhao, Y, Chui, Y, Qi X, Burns, SA, Stokes Vector Analysis of Adaptive Optics Images of the Retina, Optics Letters, 33, 137-140, 2008, PMCID: PMC2710772 
• Song H, Qi X, Zou W, Zhong Z, Burns SA, Dual electro-optical modulator polarimeter based on adaptive optics scanning laser ophthalmoscope Optics Express, Vol. 18, Issue 21, pp. 21892-21904 (2010) PMCID: PMC2972199 
• VanNasdale DA, Elsner AE, Hobbs T, Burns SA. Foveal phase retardation changes associated with normal aging. Vision Res. 2011 Nov;51(21-22):2263-72. Epub 2011 Aug 27. PMID: 21893077; PMCID: PMC3319026. 
• VanNasdale, DA, Elsner, AE, Peabody T, Kohne KD, Malinovsky VE, Haggerty BP, Weber A, Clark CA, Burns SA, Henle Fiber Layer Phase Retardation Changes Associated with Age-related Macular Degeneration, " Invest Ophthalmol Vis Sci. 2015 Dec 18;56(1):284-90. doi: 10.1167/iovs.14-14459. PMCID: PMC4294289 

 Working with Francois Delori I helped get better estimates of crystalline lens density and macular pigment absorption and with Ann Elsner we looked at the relation between macular pigment distributions and cone pigment distributions

 Representative Publications: 

• Delori, FC, and Burns SA. "Fundus reflectance and the measurement of crystalline lens density" J. Opt. Soc. Amer. A. 13,215-226, 1996.
• Elsner, AE, Burns, SA, Beausencourt, E, and Weiter, JJ, "Foveal cone photopigment distribution: small alterations associated with macular pigment distributions", Invest. Ophthalmol. Vis. Sci. 39,2394-2404 1998
• Delori, F. C., D. G. Goger, B. R. Hammond, D. M. Snodderly and S. A. Burns (2001). "Macular pigment density measured by autofluorescence spectrometry: comparison with reflectometry and heterochromatic flicker photometry." J Opt Soc Am A Opt Image Sci Vis 18(6): 1212-30. 2001

Ann Elsner started her retinal imaging lab to use the newly invented SLO to investigate the retina.  I worked with her on some of her innovations in using IR imaging, polarization, and multiply scattered light imaging to separate out different properties of the retina in order to improve contrast.  She also developed an imaging retinal densitometer which I cover elsewhere

 Representative Publications: 

•  Elsner AE, Burns SA, Hughes GW, and Webb RH "Reflectometry with a Scanning Laser Ophthalmoscope," Applied Optics, 31, 3697-3710, 1992.
• Elsner, AE, Burns SA, and Weiter JJ, "Retinal Densitometry in retinal tears and detachments", Clinical Vision Sciences 7, 489-500, 1992 
•  Elsner, AE, and Burns, SA and Webb RH "Mapping Cone Pigment Optical Density in Humans" J. Opt. Soc. Amer. 10, 52-58, 1993   
• Burns, SA, Wu, S., Delori, F. and Elsner AE "Direct Measurement of Human Cone Photoreceptor Alignment" J. Opt. Soc. Amer. A. 12, 2329-2338, 1995.  
• Delori, FC, and Burns SA. "Fundus reflectance and the measurement of crystalline lens density" J. Opt. Soc. Amer. A. 13,215-226, 1996.        
• Burns, SA, Wu, S, He, J, and Elsner, AE “Variations in photoreceptor directionality across the central retina”, J. Optical Society Amer, A 14, 2033-2040, 1997. PMCID: PMC3395223
• Marcos, S, Burns, SA, and He, J "A Model for cone directionality reflectometric measurements based on scattering." Journal of the Optical Society of AmericaA 15, 2012-2022, 1998.
•  Elsner, AE, Burns, SA, Beausencourt, E, and Weiter, JJ, "Foveal cone photopigment distribution: small alterations associated with macular pigment distributions", Invest. Ophthalmol. Vis. Sci. 39,2394-2404 1998
• Marcos, S, and Burns,  S.A. “Cone spacing and waveguide properties from cone directionality measurements” J. Opt. Soc. Amer. A 16, 995-1004, 1999. PMCID: PMC2882181
• He, JC, Burns,  S.A., and Marcos, S. “Comparison of cone directionality determined by psychophysical and reflectometric techniques” Journal of the Optical Society, A, 16:2363-2369, 1999. PMC2970515 
• Delori, F. C., D. G. Goger, B. R. Hammond, D. M. Snodderly and S. A. Burns (2001). "Macular pigment density measured by autofluorescence spectrometry: comparison with reflectometry and heterochromatic flicker photometry." J Opt Soc Am A Opt Image Sci Vis 18(6): 1212-30. 2000
• Elsner, A.E., Burns, S.A., and Weiter, J.J. “Cone Photopigment In Older Subjects: Decreased Optical Density In Early Age-Related Macular Degeneration” J Opt Soc Am A Opt Image Sci Vis 19: 215-222, 2002., PMID: 11778727 PMC2981061
•  Prieto, P, McLellan, J.S., and Burns, S.A. Investigating The Light Absorption In A Single Pass Through The Photoreceptor Layer By Means Of The Lipofuscin Fluorescence. Vision Research 45 (15): 1957-1965, 2005, PMCID: PMC1479308
• Luo, T, Warner, RL, Walker, BR, Sapoznik, KR, Burns, SA, “Template free eye motion correction for scanning systems”, Optics Letters, Vol. 46, Issue 4,pp. 753-756 (2021) https://doi.org/10.1364/OL.415285 PMID: 33577506 PMCID: PMC8447858
• Swanson, WH, Burns, SA, King BJ, Interpreting Retinal Nerve Fiber Layer Reflectance Defects Based on ­­­Presence of Retinal Nerve Fiber Bundles, Optometry and Vision Science: May 2021 - Volume 98 - Issue 5 - p 531-541 PMID: 33973913 PMCID: PMC8132612 DOI: 10.1097/OPX.0000000000001690