Measurement and correction of transverse chromatic offsets for multi-wavelength retinal microscopy in the living eye

Photoreceptor outer segments have been modeled as stacked arrays of discs or membrane infoldings containing visual pigments with light-induced dipole moments. Waveguiding has been excluded so fields diffract beyond the physical boundaries of each photoreceptor cell. Optical reciprocity is used to argue for identical radiative and light gathering properties of pigments to model vision. Two models have been introduced: one a macroscopic model that assumes a uniform pigment density across each layer and another microscopic model that includes the spatial location of each pigment molecule within each layer. Both models result in highly similar directionality at the pupil plane which proves to be insensitive to the exact details of the outer-segment packing being predominantly determined by the first and last contributing layers as set by the fraction of bleaching. The versatility of the microscopic model is demonstrated with an array of examples that includes the Stiles-Crawford effect, visibility of a focused beam of light and the role of defocus.

Section: Dipolar Antenna Model Of Stacked and Ordered Pigmentssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Directional sensitivity of the retina: A layered scattering model of outer-segment photoreceptor pigments

Vohnsen

2014

“…Thus high transverse resolution can be achieved even for very large bandwidths. Similar to LCA, TCA depends on the separation between imaging wavelengths and can be quite pronounced when visible light (543-711nm) and infrared light (842nm) is used simultaneously [77]. For TCA compensation the eye needs to be displaced laterally [76].…”

Section: Chromatic Aberrationmentioning

confidence: 99%

Review of adaptive optics OCT (AO-OCT): principles and applications for retinal imaging [Invited]

Pircher

Zawadzki

2017

149

Abstract:In vivo imaging of the human retina with a resolution that allows visualization of cellular structures has proven to be essential to broaden our knowledge about the physiology of this precious and very complex neural tissue that enables the first steps in vision. Many pathologic changes originate from functional and structural alterations on a cellular scale, long before any degradation in vision can be noted. Therefore, it is important to investigate these tissues with a sufficient level of detail in order to better understand associated disease development or the effects of therapeutic intervention. Optical retinal imaging modalities rely on the optical elements of the eye itself (mainly the cornea and lens) to produce retinal images and are therefore affected by the specific arrangement of these elements and possible imperfections in curvature. Thus, aberrations are introduced to the imaging light and image quality is degraded. To compensate for these aberrations, adaptive optics (AO), a technology initially developed in astronomy, has been utilized. However, the axial sectioning provided by retinal AO-based fundus cameras and scanning laser ophthalmoscope instruments is limited to tens of micrometers because of the rather small available numerical aperture of the eye. To overcome this limitation and thus achieve much higher axial sectioning in the order of 2-5µm, AO has been combined with optical coherence tomography (OCT) into AO-OCT. This enabled for the first time in vivo volumetric retinal imaging with high isotropic resolution. This article summarizes the technical aspects of AO-OCT and provides an overview on its various implementations and some of its clinical applications. In addition, latest developments in the field, such as computational AO-OCT and wavefront sensor less AO-OCT, are covered. 1178-1181 (1991). 2. M. Wojtkowski, B. Kaluzny, and R. J. Zawadzki, "New directions in ophthalmic optical coherence tomography," Optom. Vis. Sci. 89(5), 524-542 (2012). 3. T. E. de Carlo, A. Romano, N. K. Waheed, and J. S. Duker, "A review of optical coherence tomography angiography (OCTA)," Int J Retina Vitreous 1(5), 5 (2015). 4. W. Drexler and J. G. Fujimoto, "State-of-the-art retinal optical coherence tomography," Prog. Retin. Eye Res.27(1), 45-88 (2008). 5. G. Walsh, W. N. Charman, and H. C. Howland, "Objective technique for the determination of monochromatic aberrations of the human eye," J. Opt. Soc. Am. A 1(9), 987-992 (1984). 6. J. Liang and D. R. Williams, "Aberrations and retinal image quality of the normal human eye," J. Opt. Soc. Am.A 14(11), 2873-2883 (1997). Office, 2014). 27. J. Liang, B. Grimm, S. Goelz, and J. F. Bille, "Objective measurement of wave aberrations of the human eye with the use of a Hartmann-Shack wave-front sensor," J. Opt. Soc. Am. A 11(7), 1949-1957 (1994). 28. M. Laslandes, M. Salas, C. K. Hitzenberger, and M. Pircher, "Influence of wave-front sampling in adaptive optics retinal imaging," Biomed. Opt. Express 8(2), 1083-1100 (2017). 29. S. Tuohy and A. G. Podoleanu,...

“…The AOSLO imaging system itself is almost identical to that reported previously from our lab [28], with the exception of a piezo tip/tilt mirror (Physik Instrumente (PI), Germany) replacing the original galvonometer slowscanning mirror. The role of the tip/tilt mirror is threefold: (1) to generate the necessary ramp signal needed for the slow scan (30 Hz), (2) to feed the y-motion of the eye in to the piezo, and (3) to feed the x-motion of the eye in to the piezo.…”

Section: System Hardwarementioning

confidence: 98%

Active eye-tracking for an adaptive optics scanning laser ophthalmoscope

Sheehy

Tiruveedhula

Sabesan

et al. 2015

Self Cite

Abstract:We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eyetracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone.