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The purpose of this study was to evaluate color vision during high altitude mountain climbing by applying the Mollon-Reffin Minimalist test to 14 climbers, all of whom were participating in the expedition to Ama Dablam (6,812 m) in Nepal. Before leaving for Nepal (at 300 m), all 28 eyes showed normal color vision in all 3 axes. At 1,300 m, 100% of eyes showed normal color vision in the protan and deutan axes, while 25% showed minimally reduced color discrimination in the tritan axis. At 4,000 m, 100% showed normal deutan axis, 4% minimally reduced protan axis, and 72% minimally reduced tritan axis discrimination. At 5,400 m 100% of eyes tested showed normal protan and deutan axis discrimination, while 75% showed minimally and 25% moderately reduced tritan axis discrimination. Back home at 300 m 3 days after return, 100% showed normal deutan, 4% minimally reduced protan, and 38% minimally reduced tritan axis discrimination. One year later, all eyes showed normal color vision in all three axes. Changes in tritan axis discrimination correlated well with increased heart rate (r = 0.69; p = 0.0001) and decreased oxygen saturation (r = 0.71; p = 0.001) at high altitude. This study shows that the tritan color vision axis is predominantly affected at high altitude, but that this reduced color discrimination is transient.
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Color vision has been reported to be affected
in simulated hypoxic conditions (Wilmer
and Berens, 1918; Velhagen, 1936; Schmidt,
1937; Kobrick, 1970; Smith et al., 1976; Vingrys
and Garner, 1987; Richalet et al., 1999) as well
as during exposure to altitude hypoxia (Mod-
ugno, 1982; Richalet, 1983; Richalet et al., 1988;
Richalet et al., 1989; Karakucuk et al., 2004). The
tests used to detect color vision changes in
these studies were anomaloscopes (Richalet,
1983; Vingrys and Garnes, 1987; Richalet et al.,
1988; Richalet et al., 1989; Richalet et al., 1999),
American Optical HRR plates (Vingrys and
Garner, 1987), desaturated D15 panel (Leid and
Campagne, 2001), or the Farnsworth–Munsell
100-hue (FM-100 hue) test (Smith et al., 1976;
Karakucuk et al., 2004). Most previous studies
tested only a part of the color vision spectrum
Volume 9, Number 1, 2008
© Mary Ann Liebert, Inc.
DOI: 10.1089/ham.2008.1034
Color Vision in the Tritan Axis Is Predominantly
Affected at High Altitude
Tekavcˇicˇ-Pompe, Manca, and Igor Tekavcˇicˇ. Color vision in the tritan axis is predominately af-
fected at high altitude. High Alt. Med. Biol. 9:38–42, 2008.—The purpose of this study was to eval-
uate color vision during high altitude mountain climbing by applying the Mollon–Reffin Mini-
malist test to 14 climbers, all of whom were participating in the expedition to Ama Dablam (6812
m) in Nepal. Before leaving for Nepal (at 300 m), all 28 eyes showed normal color vision in all
3 axes. At 1300 m, 100% of eyes showed normal color vision in the protan and deutan axes, while
25% showed minimally reduced color discrimination in the tritan axis. At 4000 m, 100% showed
normal deutan axis, 4% minimally reduced protan axis, and 72% minimally reduced tritan axis
discrimination. At 5400 m 100% of eyes tested showed normal protan and deutan axis discrim-
ination, while 75% showed minimally and 25% moderately reduced tritan axis discrimination.
Back home at 300 m 3 days after return, 100% showed normal deutan, 4% minimally reduced
protan, and 38% minimally reduced tritan axis discrimination. One year later, all eyes showed
normal color vision in all three axes. Changes in tritan axis discrimination correlated well with
increased heart rate (r0.69; p0.0001) and decreased oxygen saturation (r0.71; p0.001)
at high altitude. This study shows that the tritan color vision axis is predominantly affected at
high altitude, but that this reduced color discrimination is transient.
Key Words: color vision; tritan/protan/deutan color vision axis; natural hypoxic conditions;
Mollon–Reffin “Minimalist” test
Eye Clinic, University Medical Centre, Ljubljana, Slovenia.
Department of Neurosurgery, University Medical Centre, Ljubljana, Slovenia.
and were therefore able to demonstrate only
changes in the red–green chromatic axis. For
this reason, predominantly a decrease in green
versus red sensitivity was shown (Richalet et
al., 1988; Richalet et al., 1989; Richalet et al.,
1999) at high altitude. However, the study by
Smith et al. (1976) demonstrated the specific ef-
fect of simulated hypoxia on color vision per-
formance, which consisted of a greater pro-
portion of errors in the tritan axis. A similar
effect was demonstrated at moderate altitude
(3000 m) (Karakucuk et al., 2004).
The aim of this study was to monitor color
vision changes during the ascent to 5400 m
without supplemental oxygen by using the
Mollon–Reffin Minimalist test, which enables
testing color vision in the deutan, protan, and
tritan color vision axes.
Fourteen mountain climbers (28 eyes) were
included in the study (1 female and 13 male,
mean age 52.4 12.2 yr). They were all partic-
ipants in an October 2005 Slovenian expedition
to Ama Dablam (6812 m), a summit located in
Nepal in the Himalayan range. All mountain
climbers were seasoned amateurs and were ac-
customed to living at an altitude of around 300
m. None of the participants had any color vi-
sion deficiencies (which was documented
through Ishihara plates and the FM-100 hue
test). Their visual acuity was excellent without
any, or with very mild, spectacle correction.
Testing was performed in Ljubljana (300 m,
28 eyes tested) before leaving for Nepal and
then in Katmandu (1300 m, 28 eyes tested), at
base camp (4000 m, 28 eyes tested), and at the
first camp (5400 m, 8 eyes tested). Three days
after returning to Ljubljana, 12 climbers (24
eyes) were retested. Between each test at dif-
ferent altitudes, 3 to 5 days had passed. At each
altitude, besides color vision, three other pa-
rameters (blood pressure, heart rate, and oxy-
gen saturation) were also measured. Twelve
climbers (24 eyes) repeated color vision testing
1 yr after returning from the expedition.
Color vision was tested with the Mollon–Ref-
fin Minimalist test (Mollon et al., 1991). This test
has shown its value because it is quick to ad-
minister and presents the easiest possible task
to the patient, who is required simply to iden-
tify a colored probe chip among five achromatic
distracter chips of varying lightness. The probe
chips vary in chroma, and their chromaticities
lie along dichromatic confusion lines (protan,
deutan, and tritan) that pass through the chro-
maticity of the achromatic chips. As in the first
Ishihara plate, the first chip used is a saturated
orange, which does not lie on any confusion
line, to demonstrate the task and identify pre-
tense or gross pathology. A simple staircase
procedure is then used to establish, for each
confusion line, the number of the chip that can
be reliably distinguished from the distracters.
Altogether there are 15 chips, 5 from each con-
fusion line (deutan, protan, and tritan). The in-
vestigator marks down a number for the last
chip distinguished from distracters (1, normal;
2, minimally reduced; 3, moderately reduced; 4,
markedly reduced; 5, extremely reduced color
vision in a particular axis). The test has proved
its value in testing children (Shute et al., 1998)
and could also be very useful in testing color
vision in extreme environmental conditions
such as high altitude. The value of this test is in
monitoring acquired color deficiencies, and it
can therefore represent an alternative to the FM-
100 hue test or desaturated D-15 test, both of
which demand more time to be completed
(Mollon et al., 1991). Testing conditions were
uniform for all: a bright sunny day was chosen,
the climbers were facing the northern sky, and
sunglasses were not worn before or during the
test. Each eye was tested separately.
Oxygen saturation (S
) and heart rate were
measured with a pulse oximeter (SIMS-BCI,
Inc; 3301, Waukesha, Wisconsin, USA), and
blood pressure was measured with a sphygmo-
manometer (Accoson LTD, London, England).
Statistical significance was set at p0.05,
whereas for correlation Spearman rwas used.
Color vision changed with altitude. Changes
in the deutan axis (green) and the protan (red)
axis were minimal, whereas changes in the tri-
tan (blue) axis were moderate (r0.48; p
Normal color vision was observed in all eyes
tested (28/28) at the initial altitude (300 m) in
all three color vision axes. At 1300 m, no
changes were observed in the deutan or protan
axis, but 7/28 eyes tested showed minimal
changes in the tritan axis. At 4000 m there were
no changes in the deutan axis, whereas 1 of 28
eyes tested showed minimal changes in the
protan and 20 in the tritan axis. At 5400 m, no
changes in the deutan and the protan axis were
observed in 8/8 eyes tested, while all eyes
tested showed abnormal color discrimination
in the tritan axis (6/8 minimal and 2/8 mod-
erate). Back at 300 m, no changes in the deutan
axis were observed in 24/24 eyes tested,
whereas 1 eye showed minimal changes in the
protan axis. Nine eyes, among them all 8 with
changes in the tritan axis at 5400 m, showed
minimal changes in the tritan axis. Details are
shown in Fig. 1.
Twelve climbers were retested 1 yr later, and
no color vision changes were shown in any
Blood pressure, oxygen saturation, and heart
rate changed with altitude. The ranges for
blood pressures (systolic and diastolic), oxygen
saturation, and heart rates at different altitudes
are shown in Table 1.
A correlation between color vision and other
parameters was found. Reduced color vision in
the tritan axis correlated well with increased
heart rate (r0.69; p0.0001) and decreased
oxygen saturation (r0.71; p0.001) at high
altitude. Details are shown in Fig. 2.
This study showed reduction in the tritan
color vision axis with increased altitude. Color
vision changes were detected with the mini-
malist test, which proved to be very useful for
this purpose. Tritan color vision changes cor-
related well with increased heart rate and de-
Normal Minimal reduction Moderate reduction
FIG. 1. Color vision changes in the deutan, protan, and tritan axes during the mountain ascent at four different al-
titudes. Results are shown in percentage of eyes tested at each altitude.
creased oxygen saturation at high altitude.
Changes in color vision were, however, not
permanent, since 1 yr after the expedition all
the climbers showed normal color vision.
High altitude hypoxia can trigger color vi-
sion reduction, which has been previously de-
scribed in experimental hypoxic conditions
where the tritan axis was predominately af-
fected (Smith et al., 1976) and in natural hy-
poxic conditions at moderate altitude (3000 m)
(Karakucuk et al., 2004). This study has shown
that color vision in the tritan axis is even more
affected at higher altitude. On the other hand,
this study showed only minimal changes in the
red (protan) and no changes in the green (deu-
tan) axis. Previous studies reported either no
changes (Leid and Campagne, 2001) or a rela-
tive decrease in green versus red (Richalet et
al., 1988) in natural hypoxic conditions. The tri-
tan axis was not tested in these studies.
It is known from other studies of retinal dis-
eases that color vision is predominantly re-
duced in the tritan color vision axis because of
the greater vulnerability of S cones in compar-
ison to L and M cones (Sample et al., 1986;
Greenstein et al., 1989).
The relatively high mean age of climbers par-
ticipating in the study (52.4 yr) could also have
partly contributed to the higher scores on the
tritan axis, as has been reported by the authors
of the test (Mollon et al., 1991). The study by
Karakucuk et al. (2004) showed an increased
number of errors using the FM-100 hue test at
3000 m in a high school student population.
The results of this study are comparable to our
results despite the age difference. In addition,
most of the changes to color vision in our study
were reversible after returning to 300 m: al-
ready 3 days upon arrival and 1 yr later, all the
eyes showed normal color vision. We are aware
1. B
, O
Altitude (m) BP syst (mmHg) BP diast (mmHg) S
(%) Hr (beats/min)
300 100–140 70–90 98–100 54–69
(n14) (125.7 11.5) (81.4 6.2) (99.3 0.6) (63.6 5.2)
1300 105–145 70–90 97–100 56–76
(n14) (127.9 13)0. (81.8 6.8) (98.8 1.1) (67.1 5.7)
4000 110–150 70–95 94–99068–84
(n14) (131.1 11.4) (86.8 6.3) (97.5 1.4) (74.4 5.5)
5400 140–150 80–90 84–92078–86
(n4) (142.5 4.6)0(85.0 3.7) (87.5 3.2) (83.0 3.2)
300 105–140 70–90 97–100 54–72
(n12) (126.3 10.8) (79.6 5.3) (99.0 0.7) (65.4 5.4)
The range of values, mean value, and standard deviation for all climbers tested are shown.
BP syst, systolic blood pressure; BP diast, diastolic blood pressure; S
, oxygen saturation; Hr, heart rate.
FIG. 2. A. Correlation between heart rate (Hr) and changes in the tritan color vision axis (Spearman r0.69; p0.0001).
B. Correlation between oxygen saturation (S
) and changes in the tritan color vision axis. (Spearman r0.71; p0.0001).
that illuminant changes minimally with alti-
tude; however, this does not change the fact
that 38% of eyes showed changes in tritan axis
upon arrival back home (at 300 m).
We conclude that high altitude can adversely
affect color vision, predominantly hue dis-
crimination on the tritan color vision axis.
The authors would like to thank Professor
John Mollon, who provided the color vision test
and gave us useful instructions, and all the par-
ticipants in the study. The authors would also
like to thank Mr. Ignac Zidar for his help in sta-
tistical evaluation of the data.
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Address reprint requests to:
Manca Tekavc
Eye Clinic
University Medical Centre
ˇeva 46
1000 Ljubljana, Slovenia
Received April 25, 2007; accepted in final
form July 19, 2007.
... In contrast, mountain climbers exposed to low O 2 concentrations at high altitudes for days can show robust and reliable decrements in performance. 26,32,34 One area of interest in studies of hypoxia has been compromises to color vision (e.g., Connolly et al.), particularly tests associated with short wavelength sensitivity. 3 Although these phenomena have been called S-cone deficits, it is unlikely that the S-cone photoreceptors are affected alone by hypoxia. ...
... This explanation would be consistent with the reported preferential loss of sensitivity along the tritan axis of the Farnsworth-Munsell 100 Hue test (FM100) 9 relative to the protan and deutan axes reported by a number of authors. 31,32,34 It should be noted, however, that the relative loss of the b-y pathway can be small and indeed some authors report losses 14,26 or even larger losses 33 of sensitivity in the r-g pathway. Further, Davies et al. 6 showed no effects and Leid and Campagne 20 showed marginal reductions in color vision, although as the authors state, the test they employed was perhaps less sensitive than those used by other researchers; e.g., Willmann et al. 34 Where deficits in the b-y and r-g color opponent channels have been tested together, there does seem to be a greater, but not exclusive loss in the b-y channel 34 although, again, this is not always the case. ...
... The Farnsworth-Munsell 100-Hue (FM100) test 9 is primarily used to assess congenital or acquired losses in the two color channels, but it has also been used to assess the effects of hypoxia on hue discriminability. 18,31,32 All of these studies have shown a loss in hue discriminability in the b-y channel (tritan axis) under hypoxic conditions ranging in altitude from 3658 to 5486 m. However, Vingrys and Garner 33 found more general losses at a simulated altitude of 3658 m and argued that those studies showing a decrement in color difference sensitivity due to hypoxia have required subjects to perform color vision tests at low light levels which have been shown many times to affect overall visual sensitivity. ...
Full-text available
INTRODUCTION: Hypoxia can be a problem for warfighters, compromising visual and cognitive performance. One area of study has been hypoxia-induced decrements in color vision.METHODS: The present study examined how hypoxia affected the perception of wavelengths associated with unique green and with unique yellow as well as discriminability by the blue vs. yellow (b-y) and the red vs. green (r-g) spectrally opponent color channels while breathing O₂ levels found at sea level and at 5500 m. Measurements of wavelengths producing unique green (minimizing response by the b-y channel) and unique yellow (minimizing response by the r-g channel) preceded measurements of wavelength discriminability near those unique hues.RESULTS: Relative to sea level, unique yellow shifted to shorter wavelengths (0.54 nm) and unique green shifted to longer wavelengths (2.3 nm) under hypoxia. In terms of an equal psychophysical scale, both unique hues shifted by similar magnitudes. Wavelength discriminability of both color channels was compromised by statistically reliable amounts of 16-17% under hypoxia.DISCUSSION: These results were consistent with previous studies and the inference that postreceptor, M-cone neurons were differentially compromised by hypoxia. However, these measurable changes in color vision due to hypoxia were not perceived by the subjects.Bierman A, LaPlumm T, Rea MS. Declines in wavelength discrimination and shifts in unique hue with hypoxia. Aerosp Med Hum Perform. 2020; 91(5):394-402.
... Apart from the motor system, physical fatigue also influences performance of other systems in the body. Fatigue, as a consequence of intense physical effort, can affect different aspects of visual performance and other visual parameters, such as visuomotor skills [7], contrast sensitivity [10], color vision [20] and intraocular pressure [15]. ...
... Color vision deficiencies can be congenital or due to acquired conditions, such as altered retinal circulation and neurodegenerative changes in well-known diseases such as glaucoma [14] and diabetic retinopathy [12], where the tritan color vision axis is predominantly affected. Changes in parvocellular visual pathway function, which is responsible for processing colored visual information, during physical effort has mainly been described in mountaineering and at high altitude and has been detected both psychophysically [5,11,20] and electrophysiologically with altered S cone function [15]. ...
... axes in altered metabolic body conditions due to the physical effort at high altitude. However, it has been shown that alterations in color vision due to changed metabolic body conditions are transient and return to normal when the physical effort at high altitude is stopped and subjects return to the initial altitude [20]. Therefore, a transient blue-yellow color vision deficiency [5,11,20] or transient S cone dysfunction [15] is described in these studies. ...
Full-text available
The purpose of this study was to establish whether physical fatigue affects color vision. Thirty healthy participants were included in the study (M:F=15:15), age 25.3±4.4 y, all professional or top amateur athletes. They were exhausted using the Wingate test (WT). Physical fatigue was determined by blood lactate level before the WT and 1, 3, 5, 7 and 10 min after. Color vision was evaluated using the Hardy-Rand-Rittler (HRR) and the Mollon-Reffin Minimalist (MRM) tests before the WT and 5, 10 and 30 min after. Five minutes after the WT 2/30 (6%) showed affected color vision in the protan axis and 25/30 (83%) in the tritan axis. Ten and 30 min after the WT all the participants showed normal color vision in both the deutan and protan axes, whereas 12/30 (40%) and 8/30 (26%), respectively, showed affected color vision in the tritan axis. A gender difference was observed in color vision deficiency and improvement, with female participants being affected more and longer. The study showed that intense physical effort affects color vision with the tritan axis being predominantly affected.
... Amplitude of circadian melatonin rhythm diminished and its relationship with respiratory quotient (RQ) weakened at a moderate altitude (Figure 1 of [125], with permission to be asked). Vision defects may be implied in melatonin rhythm alteration at HA. Exposure to HA alters color vision [126,127]. While protan (red) and deutan (green) axis discrimination seems still to be normal at 5400 m, tritan (blue) axis vision and discrimination are, on the contrary, reduced at HA [127][128][129]. ...
... Vision defects may be implied in melatonin rhythm alteration at HA. Exposure to HA alters color vision [126,127]. While protan (red) and deutan (green) axis discrimination seems still to be normal at 5400 m, tritan (blue) axis vision and discrimination are, on the contrary, reduced at HA [127][128][129]. Intense physical exercise seems to have a similar effect [130]. ...
Full-text available
Previous results evidenced acute exposure to high altitude (HA) weakening the relation between daily melatonin cycle and the respiratory quotient. This review deals with the threat extreme environments pose on body time order, particularly concerning energy metabolism. Working at HA, at poles, or in space challenge our ancestral inborn body timing system. This conflict may also mark many aspects of our current lifestyle, involving shift work, rapid time zone crossing, and even prolonged office work in closed buildings. Misalignments between external and internal rhythms, in the short term, traduce into risk of mental and physical performance shortfalls, mood changes, quarrels, drug and alcohol abuse, failure to accomplish with the mission and, finally, high rates of fatal accidents. Relations of melatonin with energy metabolism being altered under a condition of hypoxia focused our attention on interactions of the indoleamine with redox state, as well as, with autonomic regulations. Individual tolerance/susceptibility to such interactions may hint at adequately dealing with body timing disorders under extreme conditions.
... The CNS is particularly vulnerable to hypoxia because the brain [11] and retina [12] consume high levels of oxygen. In humans exposed to high-altitude hypoxia, it is common to experience visual disturbances, such as changes in color vision [13][14][15], high altitude retinopathy [16,17], optic disc edema [18,19] and alterations in multiple electroretinography (ERG) parameters [20]. Rarely, high-altitude hypoxia can lead to irreversible vision loss due to nonarteritic anterior ischemic optic neuropathy [21]. ...
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Central nervous system and visual dysfunction is an unfortunate consequence of systemic hypoxia in the setting of cardiopulmonary disease, including infection with SARS-CoV-2, high-altitude cerebral edema and retinopathy and other conditions. Hypoxia-induced inflammatory signaling may lead to retinal inflammation, gliosis and visual disturbances. We investigated the consequences of systemic hypoxia using serial retinal optical coherence tomography and by assessing the earliest changes within 24h after hypoxia by measuring a proteomics panel of 39 cytokines, chemokines and growth factors in the plasma and retina, as well as using retinal histology. We induced severe systemic hypoxia in adult C57BL/6 mice using a hypoxia chamber (10% O 2 ) for 1 week and rapidly assessed measurements within 1h compared with 18h after hypoxia. Optical coherence tomography revealed retinal tissue edema at 18h after hypoxia. Hierarchical clustering of plasma and retinal immune molecules revealed obvious segregation of the 1h posthypoxia group away from that of controls. One hour after hypoxia, there were 10 significantly increased molecules in plasma and 4 in retina. Interleukin-1β and vascular endothelial growth factor were increased in both tissues. Concomitantly, there was significantly increased aquaporin-4, decreased Kir4.1, and increased gliosis in retinal histology. In summary, the immediate posthypoxic period is characterized by molecular changes consistent with systemic and retinal inflammation and retinal glial changes important in water transport, leading to tissue edema. This posthypoxic inflammation rapidly improves within 24h, consistent with the typically mild and transient visual disturbance in hypoxia, such as in high-altitude retinopathy. Given hypoxia increases risk of vision loss, more studies in at-risk patients, such as plasma immune profiling and in vivo retinal imaging, are needed in order to identify novel diagnostic or prognostic biomarkers of visual impairment in systemic hypoxia.
... 26 Moreover, melatonin has been experimentally demonstrated to increase the ventilatory response to hypoxia. 27 On the other hand, it has been reported that color vision can be adversely affected at high altitude, especially discrimination along the tritan (blue) axis, 28 which could be related to abnormal melatonin release and wakeful status under such conditions. ...
Full-text available
The possible effects of blue light during acute hypoxia and the circadian rhythm on several physiological and cognitive parameters were studied. Fifty-seven volunteers were randomly assigned to 2 groups: nocturnal (2200-0230 hours) or diurnal (0900-1330 hours) and exposed to acute hypoxia (4000 m simulated altitude) in a hypobaric chamber. The participants were illuminated by blue LEDs or common artificial light on 2 different days. During each session, arterial oxygen saturation (Spo2), blood pressure, heart rate variability, and cognitive parameters were measured at sea level, after reaching the simulated altitude of 4000 m, and after 3 hours at this altitude. The circadian rhythm caused significant differences in blood pressure and heart rate variability. A 4% to 9% decrease in waking nocturnal Spo2 under acute hypoxia was observed. Acute hypoxia also induced a significant reduction (4%-8%) in systolic pressure, slightly more marked (up to 13%) under blue lighting. Women had significantly increased systolic (4%) and diastolic (12%) pressures under acute hypoxia at night compared with daytime pressure; this was not observed in men. Some tendencies toward better cognitive performance (d2 attention test) were seen under blue illumination, although when considered together with physiological parameters and reaction time, there was no conclusive favorable effect of blue light on cognitive fatigue suppression after 3 hours of acute hypobaric hypoxia. It remains to be seen whether longer exposure to blue light under hypobaric hypoxic conditions would induce favorable effects against fatigue. Copyright © 2015 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.
Krusche Till, Mirjam Limmer, Gernot Jendrusch, and Petra Platen. Influence of natural hypobaric hypoxic conditions on dynamic visual performance. High Alt Med Biol 00:000-000, 2019. Background: Both dynamic and static visual performances are essential for safety and motoric performance at altitude. There is a lack of information regarding alterations in dynamic visual performance (DVP) in oxygen-reduced environments. The purpose of this study was to analyze DVP in natural hypoxic conditions in a group of young, healthy hikers. Methods: DVP in four parafoveal subfields was analyzed using the computer-assisted Düsseldorf Test for Dynamic Vision. Measurements were performed twice at altitudes above 3500 m during an 8-day alpine hike. Results: On day 5 (3647 m), no changes in DVP were detected. On day 6 (4554 m), however, we found a significant reduction in DVP in the superior parafoveal retinal subfield, partly representing the lower visual field. The observed changes did not correlate with oxygen saturation, hematocrit, or cardiovascular parameters. We found no interrelation between symptoms of acute mountain sickness and DVP at altitude. Conclusions: Our data suggest that hiking at altitudes above 4500 m results in lower DVP in the visual field of healthy young people. The alteration might affect motor performance and coordination, increasing the risk of accidents.
Objective: Visual acuity and contrast sensitivity are crucial for optimal performance and safe sport activity. From a practical sport-specific perspective, visual performance is obligatory for orientation and movement control in mountainous areas. The purpose of this study was to analyze the effect of hypobaric hypoxic conditions on visual acuity and contrast sensitivity of short-term and middle-term acclimatized healthy young people. Design: This study used a repeated-measure design with ten eye-healthy and physically active students representing different types of sports. Methods: With the help of a computer-based Landolt C and a Sine Wave Contrast test, visual performance was investigated similar before (156 m), during a nine-day high-altitude sojourn (sleeping level: 890-4640 m), and three months later (156 m). All tests were performed under standardized illumination conditions. Additionally, morning blood oxygen saturation, hematocrits, hemoglobin, body mass, and self-reported symptoms of acute mountain sickness criteria were determined. Results: Whole blood oxygen saturation declined during altitude exposure. The analysis of central visual performance at altitude showed no effect of hypobaric hypoxia. Conclusion: Our data suggest that activity in a hypobaric hypoxia condition at moderate to high altitude levels of up to 4600 m does not affect visual acuity and contrast sensitivity of acclimatized healthy young people. However, in contrast to previous studies that outlined acutely impaired central visual performance with respect to hypoxia, we suggest that acclimatization might induce adaptation of visual perception performance and therefore reduce the risk of accidents resulting from partial loss of visual performance at altitude.
In this chapter, we will review the effects of altitude on the human visual system. In the interest of clarity, we will organize our review based on the anatomic region of the eye and its contribution to visual change during altitude exposure. We will describe the ocular anatomic and physiologic changes associated with altitude exposure and focus on the impact of these changes on visual acuity. When possible, in order to present some historical prospective, we will also include a brief history of how and when these altitude-related visual changes became known. We will also cite examples of how individual patients have been impacted by altitude-related visual changes.
Occupational chemical exposure often results in sensory systems alterations that occur without other clinical signs or symptoms. Approximately 3000 chemicals are toxic to the retina and central visual system. Their dysfunction can have immediate, long-term, and delayed effects on mental health, physical health, and performance and lead to increased occupational injuries. The aims of this chapter are fourfold. First, provide references on retinal/visual system structure, function, and assessment techniques. Second, discuss the retinal features that make it especially vulnerable to toxic chemicals. Third, review the clinical and corresponding experimental data regarding retinal/visual system deficits produced by occupational toxicants: organic solvents (carbon disulfide, trichloroethylene, tetrachloroethylene, styrene, toluene, and mixtures) and metals (inorganic lead, methyl mercury, and mercury vapor). Fourth, discuss occupational and environmental toxicants as risk factors for late-onset retinal diseases and degeneration. Overall, the toxicants altered color vision, rod- and/or cone-mediated electroretinograms, visual fields, spatial contrast sensitivity, and/or retinal thickness. The findings elucidate the importance of conducting multimodal noninvasive clinical, electrophysiologic, imaging and vision testing to monitor toxicant-exposed workers for possible retinal/visual system alterations. Finally, since the retina is a window into the brain, an increased awareness and understanding of retinal/visual system dysfunction should provide additional insight into acquired neurodegenerative disorders.
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We propose a new test that is intended as a rational reduction of existing arrangement tests of colour vision. The patient is simply required to identify a coloured probe chip placed among five achromatic distractor chips of varying lightness. The probe chips vary in chroma, and their chromaticities lie along dichromatic confusion lines that pass through the chromaticity of the achromatic chips. The test is ideal for monitoring acquired dyschromat-opsias, since it is rapid, can be administered at the bedside, and presents the easiest possible task to the patient. The test reliably classifies dichromats, and it recommends itself as an alternative to the D15, since all the probes lie directly on confusion lines. But, like other pigmentary tests, the present version of the test does not separate protanomalous and deuteranomalous observers, and the reason for this is discussed.
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A variety of retinal disease lead to a decrease in the sensitivity of the S (blue) cone pathways. To determine the possible sites and mechanisms of this loss we compared the sensitivities of an S (blue/pi-1) and an M (green/pi-4) cone pathway in patients with retinal diseases that differ as to their primary locus of sensitivity loss. The sensitivities of an S and an M cone pathway were assessed in patients with retinitis pigmentosa, insulin-dependent diabetes mellitus and open-angle glaucoma using Stiles two-color increment threshold technique. A greater loss in sensitivity of an S than an M cone pathway was found for all three disease groups; however, the diabetic patients showed a more selective loss. The results suggest that multiple sites are involved and that the combined effects of metabolic abnormalities and hypoxia contribute to the selective loss.
The examination of the aviators for the Air Service of the United States is much more strict than that of any other nation. In spite of the careful examination that eliminates men with manifestly imperfect eyes, fliers sometimes exhibit marked derangement of the ocular functions under the stress of flying and the conditions connected with it.In all articles pertaining to the selection of aviators, from the Allies or from alien countries, normal vision is considered to be the chief requisite. Surgeon H. Graeme Anderson of the Royal Naval Service and adviser to the British Air Medical Service, in a discussion of the physical qualifications of fliers, says, "Practically every one of the physicians and officers taking part in the discussion agreed that the function of vision was of the greatest importance."With this in mind, visual acuity under oxygen depletion, as compared with the behavior of this function under
5 observers with normal colour discrimination on the FM 100 hue test were subjected to 4 experimental conditions, viz. two levels of illumination: 1,637 lux (standard illumination) and 37 lux, and two levels of oxygen supply: air (21%) and 10%. The reduction of illumination alone was sufficient to introduce tritan errors in two of the five subjects. Under hypoxia however, all five observers showed a considerable increase in errors, mainly distributed in a tritan axis. The authors interpret the predominant tritan defect as a result of insult to the inner retina due to hypoxia. (Henkes - Rotterdam)
Time dependence of colour vision in the green/red axis, signs of acute mountain sickness (AMS), and plasma cortisol and ACTH concentrations were studied in eight sea-level male natives exposed 79 h to altitude hypoxia at 4,350 m. Colour vision (CV) was explored every 2 h from 08:00 to 20:00 hours by means of two portable anomaloscopes, one derived from Essilor CHROMOTEST and the other from the OSCAR. Significant diurnal variations in CV were found using both anomaloscopes, major alterations in green relative to red sensitivity being seen in the early morning. AMS scores also showed remarkable diurnal variations, parallel to those of plasma cortisol and CV, with maximum values observed at 08:00 hours. Cortisol diurnal rhythm was maintained in hypoxia, with mean concentrations higher than in normoxia. ACTH followed the same trend, but variations were not significant. Significant correlations were found between instant values of CV, cortisol, and AMS score, but no causal relationship between these variables can be ascertained.
The effects of acute (4350 m), subacute (4800 m) and chronic (4800 m) altitude hypoxia on colour vision in the green/red axis were explored in eight sea-level natives by means of a simple portable anomaloscope. Subjects were required to create a yellow colour from a mixture of red (635 nm) and green (565 nm) obtained from two electroluminescent diodes. A relative decrease in green, compared to red, sensitivity was observed in each hypoxic condition (p less than 0.001). Acclimatization to altitude, evidenced by the improvement of arterial O2 saturation (earoximeter) was accompanied by a slight but not significant return to normal colour sensitivities. The influence of factors such as fatigue, season, and age is discussed and does not seem likely to account for the observed variations.
Recent studies have suggested that the recognition of blue-yellow color vision deficits may have some predictive value in determining which ocular hypertensives are at risk of developing glaucoma and in monitoring the progress of the disease in glaucoma patients. This article reviews current theories of normal color vision and the differences that may occur in glaucoma, outlining methods of color vision testing and interpretation, and summarizing the results of recent studies.
This study reports the effect of a moderate level of hypoxia on human color discimination. We found a generalized loss of color vision affecting both red-green and blue-yellow discrimination at an altitude of 12,000 feet. Although the residual color discrimination at this altitude was within age-matched, sea-level norms, a statistically significant increase over sea level error scores was measured on the Farnsworth-Munsell 100-Hue test and the Pickford-Nicolson anomaloscope. An analysis of psychophysical and electrophysiological studies indicates that hypoxia acts by depressing retinal ganglion cell activity and that it can affect photopic visual processes as well as scotopic vision. We conclude that studies evaluating man's visual performance at altitude must consider post-receptoral processes.