This study investigated the relationship between short duration moderate-level altitude changes and changes in the internal pressure of the eye. The Mentor Tono-Pen™ was used to measure intraocular pressures of seventeen non-glaucomatous patients at ground level, in a plane at 5,000 and 10,000 feet, and again at ground level. A repeated measures analysis of variance (P\u3c0.05) was used to analyze the data. Altitude change was found to have no significant effect on intraocular pressures of subjects in this study

Semler, Christine

Vidlak, Daniel

English

CommonKnowledge

Pacific University 
CommonKnowledge 
College of Optometry Theses, Dissertations and Capstone Projects 
5-1996 
The effects of moderate-level altitude change on intraocular 
pressure 
Christine Semler 
Pacific University 
Daniel Vidlak 
Pacific University 
Recommended Citation 
Semler, Christine and Vidlak, Daniel, "The effects of moderate-level altitude change on intraocular 
pressure" (1996). College of Optometry. 1215. 
https://commons.pacificu.edu/opt/1215 
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The effects of moderate-level altitude change on intraocular pressure 
Abstract 
This study investigated the relationship between short duration moderate-level altitude changes and 
changes in the internal pressure of the eye. The Mentor Tono-Pen™ was used to measure intraocular 
pressures of seventeen non-glaucomatous patients at ground level, in a plane at 5,000 and 10,000 feet, 
and again at ground level. A repeated measures analysis of variance (P<0.05) was used to analyze the 
data. Altitude change was found to have no significant effect on intraocular pressures of subjects in this 
study. 
Degree Type 
Thesis 
Degree Name 
Master of Science in Vision Science 
Committee Chair 
Alan Reichow 
Subject Categories 
Optometry 
This thesis is available at CommonKnowledge: https://commons.pacificu.edu/opt/1215 
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THE EFFECTS OF MODERATE-LEVEL ALTITUDE CHANGE ON 
INTRAOCULAR PRESSURE 
By 
CHRISTINE SEMLER 
DANIEL VIDLAK 
A thesis submitted to the faculty of the College of Optometry Pacific 
University Forest Grove, Oregon for the degree of Doctor of 
Optometry May, 1996. 
Advisor: Alan Reichow, O.D., M.Ed., F.A.A.O. 
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AUTHORS: 
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ADVISOR: 
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Alan Reichow, O.D., M.Ed., F.A.A.O. 
BIOGRAPHY 
Christine Semler was raised in the small Midwestern town of 
Story City, Iowa. Christine attended Central College in Pella, Iowa, 
where she received a bachelor's degree with a major in biology, in 
1993. While not studying, she enjoyed competitive volleyball, 
softball and running. Christine also studied abroad for three months 
in Yucatan, Mexico, during her fina l year at Central College. Soon 
after, she began studying at Pacific University College of Optometry. 
Upon graduation, she hopes to join her husband, David Dowe, also an 
optometrist, in practice in Eugene, Oregon. 
Daniel Vidlak attended the University of Oregon for five years 
where he received his B.S. in general science and biology in 1992. 
While attending the University of Oregon he was a NCAA All-
American wrestler as well as a PAC-TEN champion. Daniel was also 
the 1993 Pan-American champion. Upon graduation Daniel plans to 
join an existing private practice in Grants Pass, Oregon. 
ABSTRACT 
This study investigated the relationship between short duration 
moderate-level altitude changes and changes in the internal pressure of the 
eye. The Mentor Tono-Pen ™ was used to measure intraocular pressures of 
seventeen non-glaucomatous patients at ground level, in a plane at 5,000 and 
10,000 feet, and again at ground level. A repeated measures analysis of 
variance (P<O.OS) was used to analyze the data. Altitude change was found to 
have no significant effect on intraocular pressures of subjects in this study. 
ACKNOWLEDGMENTS 
The authors of this study would like to extend a special thanks to 
Charles Semler, M.D. and Cheryl Semler, Jennifer Semler, M.S., and 
David Dowe, O.D. for their help in obtaining and providing necessary 
equipment, recruiting participants, and assisting in the creation of 
this thesis, respectively, An extra thank you to Dr. Alan Reichow for 
the time and effort he provided to help bring this study to 
completion. 
ABSTRACT 
This study investigated the relationship between short 
duration moderate-level altitude changes and changes in 
the internal pressure of the eye. The Mentor Tono-PenT M 
was used to measure intraocular pressures of seventeen 
non-glaucomatous patients at ground level, in a plane at 
5,000 and 10,000 feet, and again at ground level. A 
repeated measures analysis of variance (P<O.OS) was used 
to analyze the data. Altitude change was found to have no 
significant effect on intraocular pressures of subjects in 
this study. 
INTRODUCTION 
It is well researched that glaucoma is often characterized by an 
increase in intraocular pressure (lOP), which then may lead to 
significant damage of ocular health. 1 With the recent advance in the 
scope of optometry, including the management of glaucoma, it is 
important that all potential risk factors be adequately researched so 
optometrists, as well as ophthalmologists, will be able to properly 
educate glaucomatous and non-glaucomatous patients of these risk 
factors. This study explored one of these potential risk factors: a 
moderate increase in altitude. Many recreational activities such as 
heli-skiing, as well as unpressurized air flight involve this type of 
altitudinal change. 
Although Nakagawara, West, and Fulk2 proved that simulating 
moderate altitude changes in glaucoma patients had no effect on 
visual fields, we wanted to explore the relationship between lOP and 
short duration moderate altitude change on non-glaucomatous 
patients. 
This study is intended to investigate if a relationship exists 
between short term moderate-level altitude changes and changes m 
the internal pressure of the eye. To our knowledge, no direct studies 
have addressed this exact relationship. 
METHODS AND MATERIALS 
On the twenty-second and twenty-third of March, 1996, 
seventeen participants arrived at the Ames Municipal Airport in 
Ames, Iowa, at their pre-determined time. Each signed an Informed 
Consent Form before any procedures were commenced. The process 
began inside the airport terminal with each subject receiving a single 
drop of Ophthetic® (proparacaine HCL 0.5%) anesthetic in each eye. 
When the cornea was fully anesthetized, tonometry was performed 
using the Mentor Tono-Pen XL ™. lOP readings were recorded in 
millimeters of mercury (mmHg) for each eye . 
After initial measurements were completed, the subjects, as 
well as the investigator and pilot, boarded the Cessna 210 airplane. 
After take-off, the plane reached 3,000 feet in approximately fifteen 
minutes where another drop of Ophthetic® was instilled. When the 
plane reached 5,000 feet, approximately twenty minutes after take-
off, the airplane's altitude was held steady while the investigator 
completed the second tonometry reading on each participant. The 
plane then climbed to reach an altitude of 10,000 feet, approximately 
forty minutes after take-off, where the second in-flight lOP 
measurements were recorded (no additional Ophthetic® was 
instilled). When all procedures were completed, the plane descended 
to ground level, approximately fifty-five minutes after take-off, 
where one last instillation of the anesthetic and the final tonometry 
measurements were performed inside the airport terminal. 
Fol1owing this procedure, each participant received a box of artificial 
tears (Refresh Tears™) and ocular lubricants (Celluvisc®) along with 
verbal and written instructions on the use of these products. 
Volunteers were informed of the potential possibility of corneal 
epithelial involvement and if such a situation was to occur, they were 
instructed to notify the investigator immediately. 
RESULTS 
The clinical findings for the seventeen participants tested are 
listed in Table 1. The data analysis is then listed in Table 2, followed 
by a summary graph. The participants' lOPs from left and right eyes 
were averaged resulting in the mean lOP. The participants' mean 
lOP at pre-flight, at 5,000 feet, 10,000 feet and at post-flight were 
compared to one another to see if a significant relationship existed. 
We found no significant difference between mean lOP at the various 
altitudes measured (repeated measures analysis of variance p< 0.05). 
subJects 1 Pre uu 1 Pre u~ MtAN PRE 5000 ft. OS 5000 ft. DO MEAN 5000 I 10000 ft. OS 1 0000 ft. DO 
I I -x1- -x2-l 
1 Kp 15 14 14.5 16 15 1 s.s 14 14 
2 SUL 16 15 \ 15.5 1 9 1 8 18.5 18 1 9 
3 RB 17 15 16.0 12 13 12.5 11 13 
4 SB 16 13 14.5 18 17 17.5 16 19 
5 MS 14 12 13.0 15 12 13.5 15 18 
6 JS 16 151 15.5 13 15 14.0 15 12 
7 GT 1 8 1 9 18.5 17 18 17.5 18 1 9 
8 RH 21 20 20.5 1 6 15 15.5 19 20 
9 KH 16 15\ 15.5 13 1 5 14.o I 1 9 20 
13 \ 13\ 
I 
10 MR 14 13.5 11 12 11.5 I 2 
1 1 LY 13 14 13.5 15 13 14.0 171 1 8 
12 RB ~ 18 19 18.5 20 \ 18 19.0 18j 1 5 
13 RODB 16 13 1 14.5 16 15 15.5 22 1 8 
14 HB 18 16 n.e lS I 29 19.8 n 1 6 
15 TH 15 15 15,. 8 14 1,5 14.5 12 1 3 
.. 
1 6 JR 20 20 2!Ul 17 16 16.5 18 17 
17 JB 13 13 13.0 12 13 12.5 12 1 2 
--- -
.. 
MEAN 1 tHHHl I Post DO Post OS MEAN POST 
x3 I I l-x4-
1 14.0 15 13 14.0 
2 18.5 \ 13 14 13.5 
3 12.o I 14 15 I 14.5 
I 4 17.5 15 15 15.0 
5 16.5 13 1 1 12.0 
6 13.5 1 6 13 14.5 
7 18.5 16 17 16.5 I 
8 19.5 18 20 19.0 
9 19.5 1 14 15 14.5 
1 0 12.5 11 12 11.5 
11 I 7.5\ 14 14 14.0 
12 16.5 16 17 16.5 
13 2o.o 1 17 18 1 /.5 
14 16.5 \ 14 14 1 14.0 
15 12.5 \ IS 13 ' 14.0 
1 6 17.5 \ 19 17 18.0 
'- 171 12.o I 14 \ 12 13.0 
TABLE 2 
One Factor ANOVA-Repeated Measures for X1 ... X4 
Source: df: Sum of Squares· Mean Square· F-test: P value: 
Between subjects 1 6 241.191 15.074 5.275 .0001 
Within subjects 51 145.75 2.858 
treatments 3 16.676 5.559 2 .067 . 11 7 
residual 48 129.074 2.689 
Total 67 386 . 941 
Reliability Estimates for- All treatments: .81 Single Treatment: .517 
One Factor ANOVA-Repeated Measures for X1 ... X4 
G roup: c ount: Mean: d St . Dev.: d E St . rror: 
MEAN PRE 1 7 15.794 2.346 .569 
MEAN 5000 1 7 1 5. 353 2.344 .568 
MEAN 10000 1 7 1 6.147 2.816 .683 
MEAN POST 1 7 14.824 2.054 .498 
One Factor ANOVA-Repeated Measures for X1 ... X4 
Comparrson: Mean Diff. : Fisher PLSD: Scheffe F-test: Dunnett t: 
MEAN PRE vs. MEAN 5000 . 44 1 . 943 .205 .784 
MEAN PRE vs. MEAN 1 00 .. . -. 35 3 . 943 . 1 3 1 .628 
MEAN PRE vs. MEAN POST . 971 . 9 4 3. .993 1. 726 
MEAN 5000 vs. MEAN 10 .. . -. 794 .943 .664 1. 412 
MEAN 5000 vs. MEAN PO .. . . 529 .943 .295 . 941 
• Significant at 90% 
Ol 
I 
E 
E 
0.. 
0 
z 
<:( 
w 
2 
TABLE 2 (CON'T) 
One F~ c tor /\NOVA- Il e pe 3 leu Mea s ur e s for Xi ... X4 
Co tlliJ ~It isrlll: Mu ; tll Dil L: 
[MEAN IOUOO vs . MEAN fJ . .. !1. 3 :24 
Fi:, ltcr f)L S IJ : 
j. 9 4 3 . 
• Si gtl ili cJII\ al 90% 
SUMMARY GRAPH 
T T T / 
1 5- / 
1 o-
5-
0 V I I I I 
/ 
PRE (0) 5,000 10,000 POST (0) 
ALTITUDE (Ft) 
Sclt PIIo F- \c sl : 
r 1. EJ4 G 
D lllll iP\\ t: 
l2.3 S J 
DISCUSSION 
The goal of this study was to explore if a relationship exists 
between lOP and short term (fifty-five minutes total) moderate 
altitude change. A significant relationship did not exist in this study. 
Presently, we have not found any sources that have studied the 
relationship between lOP and short duration moderate altitude 
change. We suggest a follow-up study to serve as verification. 
Another possible weak area in this study involves the methods 
used for obtaining lOP. Although the Tono-pen XLTM shows a 
consistent slight underestimation of lOP compared to the Goldman 
applanation method, 3•4 it still may have significantly altered our 
results. Along with this, the participants while in the aircraft, moved 
around significantly during tonometry readings due to in-flight 
turbulence. 
Baudouin5 showed that topical anesthetics consistently 
decrease lOP for up to fifteen minutes after instillation. In this study 
three drops of anesthetic were used. The drops were instilled at 
time zero, fifteen minutes, and fifty-five minutes. Bearing this in 
mind, future studies could be done using non-contact tonometry to 
eliminate anesthetics as a possible source of error. 
Although fifty-five minutes of moderate altitude change had no 
significant effect on lOP of the seventeen subjects in this study, it 
would be interesting to investigate if a longer duration of altitude 
change, as well as an increased number of subjects would 
demonstrate a significant change in lOP. 
CONCLUSION 
Under short term exposure to moderate altitude change, this 
study found no fluctuation in lOP. This suggests that air travel or 
other activities with moderate altitude change have no significant 
effect on lOP, thus eliminating moderate altitude as a possible risk 
factor to discuss with patients. 
REFERENCES 
1. Anderson DR. The mechanisms of damage of the optic nerve. In: 
Krieglstein OK, Leydhecker W, eds. Glaucoma Update II. New York: 
Springer-verlag, 1983:89-93. 
2. Nakagawara, West, and Fulk. Effect of simulated altitude on the 
vision fields of glaucoma patients and elderly. Journal of Optometry 
and Vision Science 1991 May; 68 344-350. 
3. Kao SF, Lichter PR, Bergsrrom Tj, it al. Clinical comparison of the 
Oculab Tonopen to the Goldman applanation tonometer. 
Ophthalmology 1987; 94(12): 168-73. 
4. Whitacre MM, Emig M, Hassanein K. The effect of Perkins, 
Tonopen and Shiotz tonometry on intraocular pressure. Am j 
Ophthalmology 1991; 111(1): 59-64. 
5. Baudouin C., et al. Influence of topical anesthesia on tonometric 
values of intraocular pressure. Opthalmologica 1994; 208: 309-313. 
6. Nakagawara VB. The relevance of vision defects in the medical 
certification of civilian airmen. In: Gall DA, Idmondson LL, eds. 
Proceedings of the 1988 Northeastern State University Symposium 
on Theoretical and Clinical Optometry. Northeastern State University, 
Tahlequah, OK 1988:59-71. 
7. Kokame, Malcolm, Ing. Intraocular gas and low-altitude au flight. 
Retina 1994; 14(4): 356-358. 


The effects of moderate-level altitude change on intraocular pressure

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