ACTA BIOLOGICA CRACOVIENSIA

CAROTENOIDS AND VISION
INVITED LECTURES
Disturbed accumulation and abnormal
distribution of macular pigment in retinal
disorders
Tos TJM Berendschot
University Eye Clinic Maastricht, PO Box 5800, 6202 AZ
Maastricht, The Netherlands
Macular pigment (MP) consists of different xanthophylls, lutein
and zeaxanthin and meso- zeaxanthin. It is highly accumulated
along the axons of the cone photoreceptors in the central retina.
The concentration and spatial deposition of MP, which are entirely
of dietary origin, vary substantially between normal subjects. In
general, MP shows a peak at the foveal centre, that rapidly
decreases with eccentricity. However, recently it has been shown
that in macular telangiectasia type 2, the MP is reduced within the
central retina with a surrounding ring-like structure of preserved
MP at about 6 degrees eccentricity. Further, the Sjögren-Larsson
syndrome appears to be a disease with a genetically caused deficiency
of MP. The mechanism of deposition of MP in the central
retina is still unknown. The latter diseases, with their inability to
accumulate MP in the central retina, might serve as a model to
elucidate the mechanisms of MP deposition in the retina.
Light distributions on the retina: relevance to
macular pigment photoprotection
Richard Bone, Jorge Gibert, Anirbaan Mukherjee
Department of Physics, Florida International University,11200 SW
8th Street, Miami, FL 33199, USA, bone@fiu.edu,
jorge.gibert@fiu.edu anirbaan8280@gmail.com
Purpose: Light exposure has been implicated in age-related macular
degeneration (AMD). This study was to measures the cumulative
light distribution on the retina over extended periods. Since
AMD damage is most pronounced in the macula, we hypothesize
that this is where light distributions would peak. If this is correct,
macular carotenoids would be ideally located to reduce photooxidative
damage.
Methods: An eye-tracker recorded a video of the subject's field
of view, superimposed the gaze position, and recorded pupil size.
Fifteen na?ve subjects,divided into 3 age groups formed a test
group; five subjects formed a control group. In phase 1, subjects
viewed photographic images projected on a screen; in phase 2,
they observed a PowerPoint consisting of 78 images; in phase 3,
they performed arbitrary computer tasks while viewing a monitor;
in phase 4, they viewed a projected video; in phase 5, they
moved freely around the building. The control group was specifically
instructed to gaze at bright features in the field of view and,
in a second test, at dark features. All participants in the test
group were allowed to gaze freely. Using the subject's gaze coordinates
and the corresponding pupil diameter, we calculated the
cumulative light distribution over 5 minute periods on a central
~20°(H)×14°(V) area of the retina.
Results: Retinal light distributions were obtained for all 20
subjects. As expected for the control group, cumulative retinal
light distributions peaked and dipped in the fovea when the subjects
gazed at bright or dark features respectively in the field of
view. The distribution maps obtained from the test group showed
a consistent tendency to peak in the macula in phase 3, a variable
tendency in phases 4 and 5 but no tendency in phases 1 and 2.
Age was not a factor.
Vol. 53, suppl. 1, 2011
17–22 July 2011, Krakow, Poland
Conclusions: A tendency for the cumulative light distribution
on the retina to peak where macular pigment is most pronounced
appears to be a characteristic of some individuals and of certain
specific tasks, such as viewing a computer monitor. However at
this stage, we have not observed a potential relationship between
light distribution on the retina under general viewing conditions
and the spatial occurrence of AMD.
Support: NIH grant SC3GM083671 and Four Leaf Japan Ltd.
Effects of macular pigment on static and
dynamic visual function
Billy R. Hammond, Jr.
Vision Sciences Laboratory, University of Georgia, Athens, GA,
USA, bhammond@uga.edu
Introduction: It is likely that the mechanisms involved in accumulating
retinal lutein (L) and zeaxanthin(Z) (termed macular
pigment, MP) evolved outdoors. This talk will present data on the
effects of macular pigment on two ecological measures of vision:
Visibility: The ability to see distant objects is obscured due to the
preferential scatter of short-wave (blue) light in the atmosphere.
MP could extend visual range by selective filtering of blue haze
(the Visibility hypothesis) Visual reaction time (RT): The ability to
make a motor response coincide to an object in time and space is
an important skill (particularly for athletes). L and Z, in the retina
and brain, could improve neural efficiency and speed of processing
(the Neural Efficiency hypothesis) thereby improving
dynamic visual function.
Methods: 72 young healthy subjects were evaluated. MP optical
density (OD) was measured using customized HFP. Visibility
was assessed by measuring contrast sensitivity thresholds at 8
cycles/deg using an optical system that passed xenon-light
through the sine-wave grating. Blue haze was simulated using an
ecologically valid broad-spectrum filter. Coincidence anticipation
timing (CAT) was measured using individual white LEDs along a
linear 120 LED track that are lit in sequence, creating the appearance
of a small, moving light bar. Subjects pressed a button to
stop the light bar at a specified point along the track. Bar speed
was randomly varied between 5, 10, 15, and 20 MPH. Fixed reaction
time was measured by a button press in response to one of
the LEDs, repeatedly presented at the same position on the track.
Variable reaction time required a button press in response to one
of the LEDs presented at a random location along the 120 LED
track.
Results: MP was significantly related to contrast sensitivity
under blue haze conditions (p