Download ARVO 2016 Annual Meeting Abstracts 366 Optical imaging

ARVO 2016 Annual Meeting Abstracts
366 Optical imaging, adaptive optics and vision
Tuesday, May 03, 2016 3:45 PM–5:30 PM
611/612 Paper Session
Program #/Board # Range: 3799–3805
Organizing Section: Visual Psychophysics/Physiological Optics
Program Number: 3799
Presentation Time: 3:45 PM–4:00 PM
Dominant role of arachidonic acid pathways in light-activated
rod-induced neurovascular response accessed by retinal optical
imaging
Daniel Y. Tso, Momotaz Begum. Neurosurgery/Neuroscience/
Ophthalmology, SUNY Upstate Medical University, Syracuse, NY.
Purpose: Light-evoked reflectance decreases in the retina, seen
using intrinsic signal optical imaging, are of outer retinal origin and
dominated by hemodynamics. The specific pathways underlying this
neurovascular response (and imaged signals) are unknown. Most
previous studies of retinal neurovascular coupling have been in vitro
and presume an inner retinal origin. We sought to dissect the role of
signaling pathways in the stimulus-evoked neurovascular responses
in vivo through intravitreal injections of selected agents.
Methods: Using a modified fundus camera, the retinas of adult
anesthetized cats were stimulated with visible (550nm) patterned
stimuli and illuminated in the near-infrared (700-900nm), while
intrinsic optical signals were recorded with a CCD camera.
Intravitreal injections included TTX, APB/PDA, adenosine, NECA
(P1 agonist), PPOH (EET inhibitor), indomethacin (COX inhibitor),
HET0016 (20-HETE inhibitor), L-NAME (NOS inhibitor), and
Verapamil (L-type calcium channel blocker).
Results: Unlike pharmacologic injections designed to block retinal
neural activity, at the ganglion cell level (TTX) or inner retina
(APB/PDA), injections of drugs that disrupt neurovascular coupling
have a profound effect on the light-evoked retinal imaging signals.
Our data suggest that the arachidonic pathways are obligatory for
the light-induced hemodynamic response in the retina since EET
and prostaglandin inhibitors abolished the imaging signal, while
a 20-HETE inhibitor (HET0016) decreased the signal amplitude.
Inhibiting nitric oxide (NO) production using L-NAME demonstrated
a lesser contribution for NO in the imaging pathways. Verapamil,
an L-type calcium channel blocker, reduced the imaging signal
amplitude, suggesting that the light-induced neurotransmitter release
contributes to the reflectance change signal.
Conclusions: These results indicate that arachidonic acid metabolites
play a critical role in the light-evoked hyperemic response. Nitric
oxide synthesis blockers yielded minimal effects. Purinergic
pathways also play contribute to the imaging signal, but further
investigation is required to show how specific purinergic receptors
influence the signal.
Commercial Relationships: Daniel Y. Tso; Momotaz Begum, None
Program Number: 3800
Presentation Time: 4:00 PM–4:15 PM
A Programmable Aperture Adaptive Optics SLO
Stephen A. Burns, Alberto De Castro, Lucie Sawides, Ting Luo.
School of Optometry, Bloomington, IN.
Purpose: Confocal adaptive optics imaging provides high contrast,
cellular scale, images of the retina. However, confocality limits
information from the retina to primarily singly scattered light.
Imaging with multiply scattered light can provide exquisite detail
on otherwise difficult to see retinal features that are not as evident in
confocal images. Designs for capturing multiply scattered light have
been limited to a limited range of aperture designs, yet in principle it
should be possible to optimize apertures for specific retinal features.
Here we present the design and initial tests of a confocal adaptive
optics SLO (AOSLO) that uses a programmable micromirror array to
dynamically adjust the division of multiply scattered light to different
detectors.
Methods: We designed and built an AOSLO using a supercontinuum
laser (Fianium), a woofer tweeter AO subsystem, and a steerable
front end. The major difference from our previous systems is the
light detection channels. We use a reflective confocal aperture that
directs singly scattered light to an avalanche photodiode (APD).
The surround of the point spread function is magnified by 50%
and re-imaged onto a micro-mirror array (TI- DLP 6500). Each
micro-mirror is 10 microns (~ 0.15 Airy disc diameters). The array
then directs light, pixel by pixel, to one of two detectors. Apertures
were programmable from a MATLAB program that allowed
changing aperture parameters during imaging from an initial set of 5
parameterized shapes. Shapes were then uploaded to the micro-mirror
controller.
Results: Images were obtained on 3 eyes. Confocal images had high
contrast and resolution (Figure 1). Multiply scattered light images
showed expected features, with the exception of small flickers
affecting < 1% of the image pixels. Efficiency of the programmable
array was less than our system which uses movable apertures, but in
line with design efficiency for the micro-mirrors (> 80%). In practice
the multiply scattered light images were bright and did not require
increased retinal irradiance.
Conclusions: A programmable array system for dividing a single
point scanned SLO into multiple channels and to alter that division
of light on the fly holds promise for matching the imaging system
to the detection of specific retinal features. The current system has
some drawbacks. These arise from the purely complementary nature
of the two multiply scattered light images, and the addition of a small
amount of pixel noise.
Commercial Relationships: Stephen A. Burns, None; Alberto De
Castro; Lucie Sawides, None; Ting Luo, None
Support: NIH/NEI 1R0EY024315-01 Foundation Fighting
Blindness
Program Number: 3801
Presentation Time: 4:15 PM–4:30 PM
Magnification Characteristics on Optical Coherence Tomography
Systems
Dirk-Uwe G. Bartsch. Ophthalmology, Univ of California-San Diego,
La Jolla, CA.
Purpose: Recent advances in optical coherence tomography (OCT)
technology have led to the expansion of this technology into all areas
of medicine. A large number of clinical studies have been conducted
in areas such as glaucoma, macular degeneration, Alzheimer’s
disease, and others. In these studies patients with different refractive
errors are studied with different OCT devices using a variety of
imaging protocols that measure retinal thickness. Our purpose was
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ARVO 2016 Annual Meeting Abstracts
to study the lateral magnification characteristics in six different
optical coherence tomography devices in a model eye and draw
conclusions for clinical studies. Previously, we studies the variations
in magnification with different axial length. In this study we varied
axial length and refractive power.
Methods: We build an eye model with a simulated retina and an
achromatic doublet lens. The axial length of the eye model was
adjustable to yield a corresponding defocus of +4D to -10D from
emmetropia. In addition, we modified the refractive power of the
lens by adding spherical trial lenses to change refractive power.
We imaged the model eye with six different optical coherence
tomographs (CirrusOCT, Optos OCT, Optovue, SpectralisOCT,
StratusOCT, and Topcon DRI). We measured the lateral dimension of
features on the simulated retina with each instrument.
Results: In our prior study we analyzed lateral magnification with
axial length variation. The SpectralisOCT showed no magnification
error with axial length. The Topcon DRI and Optovue showed
12% and 13% variability over the defocus range, respectively. The
CirrusOCT and StratusOCT showed 30% variability and the Optos
OCT showed 45% variability over the defocus range. In the second
study we analyzed lateral magnification with refractive power.
The CirrusOCT, StratusOCT and Topcon DRI showed minimal
magnification error with refractive power change.
Conclusions: Optical coherence tomography has dramatically
altered retinal imaging and anatomical understanding. Recently,
the instruments have been used to collect cross-sectional normative
databases in large number of patients. These studies rely on the
accuracy of the instrument for different refractive powers and
different axial lengths. It appears that several instruments exhibit
lateral magnification errors that need to be considered in crosssectional studies.
Commercial Relationships: Dirk-Uwe G. Bartsch
Support: NIH grant R01EY016323, NIH grant R01EY016323, NIH
grant 1P30EY022589, Research to Prevent Blindness
Program Number: 3802
Presentation Time: 4:30 PM–4:45 PM
Through-focus binocular contrast sensitivity of monofocal and
multifocal intraocular lens predicted by an adaptive optics visual
simulator
Aixa Alarcon1, Carmen Canovas1, Silvestre Manzanera2,
Pedro Prieto2, Kendra Hileman3, Patricia A. Piers1, Pablo Artal2.
1
Abbott Medical Optics, Groningen, Netherlands; 2Laboratorio de
Optica, Universidad de Murcia, Murcia, Spain; 3Abbott Medical
Optics, Santa Ana, CA.
Purpose: Adaptive optics (AO) vision simulation is able to predict
the clinical visual outcomes of pseudophakic patients implanted
with either refractive or diffractive intraocular lens (IOL) designs
reasonably well (Schwarz et al. ARVO 2014; Manzanera et al. ARVO
2015). The purpose of this study was to evaluate the through-focus
contrast sensitivity (CS) provided by monofocal and multifocal IOLs
using the AO visual simulator.
Methods: The phase profile of an aspheric, a spherical monofocal
and three diffractive multifocal IOLs with different add powers
(+2.75, +3.25 and +4D) were induced bilaterally by an AO visual
simulator in 4 cyclopleged subjects for a 4.5 mm pupil in white light
under mesopic conditions. CS was measured at 6 and 12cpd using
the QUEST method at three different defocus positions (0, -0.75 and
-1.5D of defocus). The results at 0D were compared with the clinical
data of pseudophakic patients implanted with the same IOL designs
measured using a Vector Vision or an Optec 6500 chart.
Results: The CS at 6 and 12cpd for the five IOL designs provided
a good correlation with the clinical CS at distance. CS decreased
linearly with defocus for monofocal and multifocal IOLs (R^2> 0.81
and 0.82 for 6 and 12cpd respectively) except for the lowest-add
multifocal IOL (R^2= 0.23 and 0.20 for 6 and 12cpd respectively).
For multifocal IOLs, the higher the add power, the faster the
reduction of the CS with defocus. For example, at 6cpd, the ratio
was -0.08, -0.22 and -0.30logCS/D for 2.75, 3.25 and 4D of add
power respectively. Monofocal IOLs had higher ratio of change and
provided significantly better CS at 0 and -0.75D than multifocal IOLs
at 6 and 12cpd. At intermediate vision, the reduction of the add power
improved CS.
Conclusions: CS measured with the AO visual simulator resembled
the clinical performance of patients implanted with the same IOL
designs at far. The evaluation of the through-focus CS showed
that the CS decreased linearly with the defocus in a defocus range
between 0 and -1.5D for monofocal and multifocal IOLs with high
add power. Monofocal IOLs provided the better CS at 0 and -0.75D
while multifocal IOLs with the lower add power provided better CS
at -1.5D.
Commercial Relationships: Aixa Alarcon, AMO;
Carmen Canovas, AMO; Silvestre Manzanera, AMO (F);
Pedro Prieto, AMO (F); Kendra Hileman, AMO; Patricia A. Piers,
AMO; Pablo Artal, AMO (C)
Support: Supported by the Ministerio de Ciencia e Innovación,
Spain (grant FIS2013-41237-R & AMO. (FYEO grant)
Program Number: 3803
Presentation Time: 4:45 PM–5:00 PM
Stereoscopic acuity as a function of induced monocular defocus
measured with an adaptive optics simulator
Silvestre Manzanera1, Aixa Alarcon2, Carmen Canovas2,
Pedro Prieto1, Adrian Gambin1, Henk A. Weeber2, Patricia A. Piers2,
Pablo Artal1. 1Laboratorio de Optica, University of Murcia, Murcia,
Spain; 2AMO, Groningen, Netherlands.
Purpose: Different binocular approaches are used to correct for
presbyopia. Many of them are based in extending binocular depth
of focus by adding a relative defocus in one eye. Although it is well
known that this reduces stereoscopic acuity, the details of this process
are not completely quantified. In this study, we measured stereoscopic
acuity using a binocular adaptive optics instrument for controlled
amounts of induced defocus.
Methods: The binocular adaptive optics visual simulator allows for
the simultaneous measurement and manipulation of the optics in the
two eyes of a subject. The apparatus incorporates two programmable
modulators using liquid crystal on silicon technology for wavefront
shaping and to produce the artificial pupil respectively. The prototype
was also equipped with a stimulus generator based on a pair of microprojectors to perform visual testing through the modified optics.
Each image was independently projected over its corresponding eye
simultaneously, creating retinal disparity. Stereoscopic acuity was
measured using a three-needle test. Subjects underwent a forced
choice test, discerning if the central wire was in front or behind the
two other wires for different interocular disparities. Measurements
were performed in three normal young subjects when natural
astigmatism was corrected, with paralyzed accommodation, for a
3.5 mm artificial pupil diameter, in green (pseudo-monochromatic)
light and photopic conditions. The measurements were obtained for
one eye at best focus while in the fellow eye controlled amounts of
defocus were added.
Results: Stereoscopic acuity was best when both eyes were at
best focus (mean value 6.3 ± 3.9 arcsec) and became worse with
increasing defocus in one of the eyes. We found a reduction
of stereoscopic acuity at a rate around 55 arcsec/diopter (95%
confidence intervals: [40,60] arcsec/diopter) in the range up to 1D.
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ARVO 2016 Annual Meeting Abstracts
For larger values of defocus, stereoscopic acuity was too poor to be
measured with the instrument.
Conclusions: A binocular adaptive optics simulator was used to
study the impact of unilateral defocus on stereovision. There is a
linear reduction between induced defocus and stereoscopic acuity
for defocus values up to 1 D. Even small values of defocus, such as
0.25 D, will reduce stereoscopic acuity by a factor of 2 as a result of
different blur in the retinal images of both eyes.
Commercial Relationships: Silvestre Manzanera, AMO (F),
Voptica (I); Aixa Alarcon, AMO; Carmen Canovas, AMO;
Pedro Prieto, AMO (F), Voptica (I); Adrian Gambin, AMO (F);
Henk A. Weeber, AMOP; Patricia A. Piers, AMO; Pablo Artal,
AMO (F), Voptica (I), AMO (C)
Support: Ministerio de Ciencia e Innovación, Spain (grant FIS201341237-R) & AMO (grant FYEO )
Program Number: 3804
Presentation Time: 5:00 PM–5:15 PM
Neural Binocular Summation Altered by Abnormal Interocular
Disparities in Normally Developed Visual Systems
Robert Dowd1, Antoine Barbot1, 3, Geunyoung Yoon1, 2,
Krystel R. Huxlin1, 3, Duje Tadin3. 1Flaum Eye Institute, University
of Rochester, Rochester, NY; 2Biomedical Engineering, University
of Rochester, Rochester, NY; 3CVS Department, University of
Rochester, Rochester, NY.
Purpose: Keratoconus (KC) and monovision (MV) are two examples
of large and progressive inter-ocular disparities due to higher order
aberrations and defocus that arise after normal development of the
visual system. This study serves to investigate the ensuing changes in
binocular function associated with these two models and to test the
hypothesis that larger interocular disparities result in lower binocular
summation.
Methods: A large stroke binocular adaptive optics system was
used to correct ocular aberrations for 9 human subjects in real time.
Subjects were grouped as normal (n=4), MV (n=2) or KC (n=3) and
tested for both monocular and binocular contrast sensitivity (CS).
AO correction eliminated the contribution of ocular aberrations to
binocular function, allowing for the assessment of neural function. A
contrast sensitivity function was measured in a ±45 degree orientation
discrimination forced-choice task. Subjects were presented with
a Gabor patch stimulus (2 degrees in diameter), which varied in
contrast and spatial frequency (0.25-30 c/deg). For each subject,
binocular summation ratios (BSR) were computed by dividing
binocular CS by monocular CS of the best eye.
Results: Under full AO correction (average residual wavefront
RMS<0.05μm), subjects with large interocular differences exhibited
reduced binocular summation, relative to normal eyes. KC subjects
exhibited a large impairment in binocular summation (BS), with an
average BSR of 1.09 ± 0.28 SEM, a 41% decrease from the average
normal BSR of 1.87 ± 0.27 SEM. The interocular difference in
Keratometry value for KC subjects ranged from 1.5-28.5D. The
KC subject with the greatest interocular disparity (28.5D) displayed
strong binocular inhibition, with a BSR of 0.63 ± 0.055 SEM. MV
subjects with approximately 1.5D anisometropia also showed reduced
binocular summation, with an average BSR of 0.98 ± 0.36 SEM.
The MV subject with the most long-standing monovision exhibited
an average BSR of 0.62 ± 0.046 SEM, indicating strong binocular
inhibition as well.
Conclusions: The results of this study indicate that considerable
inter-ocular differences in optical quality detrimentally affect
binocular neural function, as illustrated by the lowered binocular
summation in KC and MV subjects. This finding suggests that
long-term visual experience with abnormal binocular visual input
alters binocular function of normally developed visual systems.
Commercial Relationships: Robert Dowd, None; Antoine Barbot,
None; Geunyoung Yoon, None; Krystel R. Huxlin, None;
Duje Tadin, None
Support: NIH EY014999
Program Number: 3805
Presentation Time: 5:15 PM–5:30 PM
Improving vision by pupil shape optimization
Sergio Bonaque-González1, 2, Norberto Lopez-Gil2, Susana Rios1.
1
Universidad de La Laguna, Santa Cruz de Tenerife, Spain; 2Grupo de
Ciencias de la Vision, Universidad de Murcia, Murcia, Spain.
Purpose: We test an alternative solution to improve visual quality
by spatially modulating the amplitude of light passing into the eye
(modulating transmittance), in contrast to traditional correction of
the wavefront phase (modulating local refractive power) achieved by
ophthalmic, contact or intraocular lenses.
Methods: A custom software programmed in MATLAB® based in
a region-growing algorithm was developed to find the pupil shape
that maximizes retinal image quality by maximizing the modulation
transfer function (MTF) weighted by the neural contrast sensitivity
function without normalization (VSMTF_abs). The algorithm was
applied to 10 wavefronts from 10 eyes:1 emmetrope; 2 myopic; 2
astigmatic; 3 keratoconic (Kc); and 2 that underwent a penetrating
keratoplasty (PK). The MTF, the point spread function (PSF) and its
convolution with an extended object were obtained and compared
with circular pupils of the same area, corresponding to a circular
pupil of a diameter of 4 mm. Robustness to decentration and rotation
of the irregular pupils was analyzed.
Results: Customized pupil shapes, usually non circular, resulted in
improvements in the image quality when compared with circular or
apodized pupils for all the cases analyzed. On average, optimized
pupils produced a range of 4 to 52% increase in the VSMTF_abs
with respect a circular pupil of the same area. Larger improvements
of the metric were obtained in the eyes with low aberrations due
to the sensitivity of high MTFs to small corrections. However, the
convoluted images show the largest benefit of this technique is
obtained in the high aberrated eyes such as Kc (see figure) and PK.
Robustness to decentration and rotation of the irregular pupil depends
on the aberration level and type, but in the worst case > 0.3 mm or 20
degrees displacement and rotation were required before reaching the
VSMTF_abs values obtained by the circular pupil.
Conclusions: Numerical simulations show that masking the aberrated
areas at the pupil plane should enhance visual function, especially
in highly aberrated eyes. This correction could be implemented in
practice using customized contact, intraocular lenses or new aniridia
implants.
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to access the versions of record.
ARVO 2016 Annual Meeting Abstracts
Left: wavefront of a keratoconic eye for 5 mm pupil. Middle:
Circular pupil of 4 mm (top) and irregular pupil with the same area
given by the algorithm (bottom). Retinal simulation of a set of
Landolt C computed for each pupil.
Commercial Relationships: Sergio Bonaque-González,
Universidad de La Laguna (P); Norberto Lopez-Gil, Universidad de
Murcia (P); Susana Rios, Universidad de La Laguna (P)
Support: Fundación Séneca Grant 15312/PI/10
These abstracts are licensed under a Creative Commons Attribution-NonCommercial-No Derivatives 4.0 International License. Go to http://iovs.arvojournals.org/
to access the versions of record.