Psychology & Health Stress and intraocular pressure ...

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Stress and intraocular pressure in open angle glaucoma a

Gert Kaluza & Heidrun Maurer a

b

Department of Medical Psychology , University of Marburg , Germany

b

University Hospital of Ophthalmology , Marburg, Germany Published online: 19 Dec 2007.

To cite this article: Gert Kaluza & Heidrun Maurer (1997) Stress and intraocular pressure in open angle glaucoma, Psychology & Health, 12:5, 667-675, DOI: 10.1080/08870449708407413 To link to this article: http://dx.doi.org/10.1080/08870449708407413

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Psychology and Health, 1997, Vol. 12, pp. 667-675 Reprints available directly from the Publisher Photocopying permitted by license only

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STRESS AND INTRAOCULAR PRESSURE IN OPEN ANGLE GLAUCOMA GERT KALUZA' and HEIDRUN MAURER2 'Department of Medical Psychology, University of Marburg, Germany 2University Hospital of Ophthalmology, Marburg, Germany Downloaded by [University of Guelph] at 17:06 14 November 2014

(Received 26 September, 1995; in final form 13 June, 1996) Elevation of intraocular pressure (IOP) in primary open angle glaucoma is hypothesized to be influenced by stress-induced activation. However, empirical support for this assumption so far is only small, and the amount of stress effects has not yet been determined as compared to other known factors that influence 10P-levels. This study investigated the impact of a mental stressor test (MST) on the IOP of open angle glaucoma patients as compared to IOP reactions provoked by the Water Drinking Test (WDT), which is a valid diagnostic procedure to detect maximum IOP levels. Assessments of cardiovascular reactions and self-ratings of psychological strain showed the MST was effective in altering general psychophysiological activation. Immediately after exposition to the mental stressor, an increase of IOP of about 1.5 mmHg on average was determined. After the WDT, averaged elevations of IOP amounted to 4 mmHg. After a 10 minutes relaxation phase during the MST, IOP scores had returned to baseline-levels. During the WDT, IOP also decreased within a 40 minutes period but still exceeded baseline-levels. The results provide evidence that psychosocial stress factors may contribute to increased IOP in open angle glaucoma, although the WDT led to more pronounced elevations of IOP and a prolonged recovery as compared to the MST.

KEY WORDS: Open angle glaucoma; mental stress; intraocular pressure; water drinking test.

INTRODUCTION Glaucoma is a threatening chronic eye disease that leads to blindness if treated insufficiently. In primary open angle glaucoma, the acqueous humour drainage is handicapped due to a rise in resistance in the trabecular meshwork in the anterior chamber of the eye. The resulting high intraocular pressure (IOP) induces degeneration of retinal ganglion cell-layer and optic nerve tissue and disturbs microcirculation in the optic nerve head. This leads to progressing visual field defects and finally to blindness (Shields and Krieglstein, 1993). Although many morphological changes in the trabecular meshwork are visible via light or electron microscope, research has not yet completely determined the real causes of glaucoma. A genetic factor is known as predisposing the development of glaucoma (Shields and Krieglstein, 1993). Psychological studies have failed to demonstrate specific personality traits of glaucoma patients (Carrieri, Gentile, Fusco and Grew, 1991; Floru and Floru, 1979; Hibbeler, 1947; Schuler, Ballin and Petermann, 1977; Torre et al., 1986; Zimet and Berger, 1960). Some of these studies report elevations of depression and anxiety scores in glaucoma patients (Carrieri et al., 1991; Floru and Floru, 1979; Torre et al., 1986). Because of their retrospective nature these results may rather reflect the patients' reactions to the chronic disease than shed light on a premorbid condition. Address for correspondence: Dr. Gert Kaluza, Medizinische Psychologie, Fachbereich Humanmedizin, Bunsenstrasse 3, D-35033 Marburg, Germany. Phone: +49 06421 28 6250, Fax: +49 06421 28 4881. 667

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vpically, a fairly constant IOP is maintained through homeostasis. A variety of factors may, however, act upon IOP. Among others, there is evidence that IOP is influenced by sympathetic (Van Alphen, 1961) and parasympathetic stimulation (Armaly, 1959). Thus, stress may contribute to an increase in IOP while relaxation may have a decreasing effect. Several mechanisms (Hyams, Bergmann and Keroub, 1982; Kass and Sears, 1977; Stone and Kuwayama, 1989) may contribute to stress-induced IOP-elevations (i.e., dilatation of the pupil, tension of intraocular muscles as well as neuroendocrinological factors, particularly with regard to glucocorticoides and catecholamines). However, only few studies have directly addressed the impact of stress on IOP-levels. Experimentally induced mental stress led to an increase of IOP in a group of myopic students as well as in normal controls, and this increase was more pronounced in the myopic group (Sauerborn, Schmitz, Franzen and Florin, 1992). Longterm stress stimulation (academic examination) was shown to slightly increase IOP in a group of non-glaucomatous students (Grignolo, Bongioanni and Carenini, 1977). With regard to glaucoma, apart from some anecdotal case reports (Croll and Croll, 1960; Inman and Lond, 1929; Kern, 1974), only the study by Grignolo et al. (1977) reported that exposure to a brief stressor (a gun shot) had an IOP increasing effect on the glaucoma patient, but not on normal controls. To summarize, up to now there are only few empirical data that demonstrate IOP-modulating effects of vegetative activation in open angle glaucoma patients, and the amount of these stress effects as compared to other factors that influence IOP levels has not yet been determined. Therefore, the present study was designed to determine reactivity of IOP to an experimentally induced mental stressor as compared to a valid physiologic stressor in open angle glaucoma patients. METHODS Subjects

Patients were recruited from the ambulatory clinic of the university’s eye hospital, Marburg, Germany according to the following criteria: (a) opthalmologic diagnosis of primary open angle glaucoma, (b) no other major medical or psychiatric condition and (c) capable of speaking and writing the German language. After informed consent, 22 patients agreed to take part in the study. Among these were 5 men and 17 women. Ages ranged from 20 to 69 years, with a median of 52 years. Education was quite heterogeneous, with 10 patients reporting a high educational level (i.e., high school or university degree), 4 patients a medium level (i.e., 10 to 12 years of education) and 8 patients a low educational level (i.e., up to 9 years of education). The mean time span since the first diagnosis of the glaucoma disease was 8.5 years and ranged from 1 to 22 years. 18 patients were receiving treatment via antiglaucomatous eye drops. We advised patients not to change their medication during the course of the study. For ethical reasons, a general withdrawal of medication though desirable from a researcher’s perspective was untenable. Procedures

All patients were admitted to the university’s eye hospital for 24 hours. In the afternoon of the first day of hospitalization the mental stressor test (MST) was conducted, and in the morning of the second day the water drinking test (WDT) was performed. In order to control for daily fluctuations of IOP as well as for repeated measurements effects, for half of the subjects this order of MST and WDT was inverted.

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669

Water Drinking Test (WDT)

As a physiologic stressor we performed the water drinking test (Leydhecker, 1950). When conducting this test, patients have to drink one litre (mostly water or herbal tea) within 30 minutes. This provokes an IOP-rise in every person, more significantly however in glaucoma patients. The WDT provides valid information about the almost highest possible IOP in an eye (Frankelson, 1974; Helal, 1988; Spaeth, 1977; Warter and Jeannenot, 1991). During the test, the clinician measured IOP before (TI) as well as 20 minutes (T2)and 40 minutes (T3) after drinking.


Mental Stressor Test (MST)

All patients were exposed to the following situations: 1. 5 min baseline: Subjects sat comfortably in an armchair with their eyes closed. They were asked to rest for a five-minute period. 2. 10 min stress condition: To induce mental stress, we used a modification of the procedure developed by Schulte, Neuss and Riiddel (1981) which had been applied similarly in various psychophysiologic studies (e.g., Steptoe and Sawada, 1989), and was also used in the study on stress-induced IOP-reactions in myopes by Sauerborn et al. (1992). Subjects were supplied with earphones and were asked to perform arithmetical mental operations under time pressure while receiving disturbing noises through the earphones. The noises represented a mixed sequence of machinegun firing, alarm sirens, and respiratory instructions which would, if followed, interfere with normal breathing patterns. These disturbances were given at a 60 to 70 db noise level. The task was to subtract aloud, continuously, and as fast as possible the number 7 starting with 1450, for a 10 minute time period. When a mistake was made, subjects had to start again from the beginning. Time pressure was induced in the following way: The subjects were told that previous subjects had managed to do an average of 23 subtractions per minute. This was a high standard and during the task subjects could not ascertain whether they were meeting this standard. 3. 10 min relaxation condition: Patients again sat comfortably in the arm chair, closed their eyes and were asked to relax. IOP was measured immediately after each of the three phases of the MST (i.e., T1: baseline, T2: stress, T3: relaxation). To assess general activiation levels we also registered heart rate (HR) as well as diastolic (DBP) and systolic (SBP) blood pressure, and patients completed a short rating scale to assess psychological strain. Measures Intraocular pressure (IOP) readings of both eyes were obtained by an ophthalmologist using a Goldmann’s applanation tonometer (Vaughan and Asbury, 1980). A tiny cylindric instrument with a plane surface is gently pressed on the topically anaesthesized cornea. A small force is then applied causing a flattening of the cornea. The force exerted at the instance of flattening is recorded on the scale of the tonometer, and this in turn is calibrated in terms of IOP. When IOP is high, more force is needed to flatten the surface just a little. IOP is indicated by mm mercury. Because IOP-scores of the right and the left eye highly correlate with each other (Davanger, 1965), we used averaged scores of both eyes in our analyses.


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Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were registered using an electronic oscillometric blood pressure-measuring apparatus with digital indicator of blood pressure and pulse values (HESTIA OZ 80). While the cuff was already fastened on the patients’ left arm, assessments were undertaken in the last minute of each of the three phases of the MST. Psychological strain was measured by a short questionaire (“Kurzfragebogen zur aktuellan Beanspruchung” [KAB] by Miiller and Basler, 1993) consisting of 8 bipolar items such as calmhervous, well-balancedhmbalanced, tensehelaxed, to be rated on a six point Likert scale. The KAB has demostrated high reliability (Alpha: 0.85; Retest: 0.83)) and validity data confirm it as a useful tool to quantify the amount of psychological strain in acute stress situations (Basler, Steinfelder, Hartnack and Kretschmer, 1987). Psychological variables: Before conducting the experimental procedures patients completed the following standardized questionaires: “Depressivitats-Skala” (DS; von Zerssen, 1976) to assess depressive mood states. This questionaire contains 16 items that cover emotional, cognitive, and motivational symptoms of depression. Subjects rate each item on a four-point rating scale (definitely true to not at all). Reliability coefficients of .82 (Re-test) and .80 (split-half) have been determined in a representative adult sample. The scale has good internal and external validity and has been a frequently used measure for assessment of mild forms of depression. Trait version of State-Trait Anxiety Inventory (STAI; German version by Laux, Glanzmann, Schaffner and Spielberger, 1981) to assess trait-anxiety. Like the original version of the STAI by Spielberger, Gorsuch and Lushene (1970), the German translation contains 20 self-evaluation items such as ‘‘I feel pleasant”, “I lack self-confidence” and “I am a steady person.” Subjects rate each item on a four-point rating scale ranging from almost always to almost never. Reliability amounts to .90 (Cronbach’s alpha) in a representative sample. The scale is valid in assessing normal as well as neurotic degrees of anxiety. Age- and sex-adjusted norms of a representative West German sample are available for both questionaires. Prior to data analysis, we transformed raw scores of the psychological questionaires into T-values. Data Analysis

To determine internal validity of the MST, we first analyzed the data on HR, DBP, SBP and psychological strain. In order to control for alpha-inflation, we conducted a multivariate analysis first, using the F-tests for Wilks’ Lambda. In the case of a significant multivariate F, we then used univariate F-Tests (ANOVAS). In the case of conflicting results (i.e., nonsignificant multivariate F but a significant univariate F for one of the dependent variables), we will also report the univariate result as a trend with only tentative interpretation (Tabachnik and Fidell, 1989). We then analyzed the IOP-data with 2 x 2 factorial dependent measures analyses of variance (MANOVA) with “Test” (WDT vs. MST) as one dependent measures factor and “Time” (T1 vs. T2; T2 vs. T3; T1 vs. T3) as the second dependent measures factor. In case of violation of assumptions of repeated measures analysis of variance (i.e., heterogenity of variances of differences), we adjusted degrees of freedom by Huyn-Feldt’s Epsilon as described by Levine (1991). Pearson correlation coefficients were computed between changes in depedent variables using [T2-T1] and [T3-T2] difference scores. All analyses were performed using the SPSS package.

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RESULTS Internal Validity of MST


Results of assessments of HR, SBP, DBP and psychological strain during the MST are displayed in Table 1. The multivariate analysis of changes in these variables over time was highly significant (F(6, 16) = 20.8; p < .OOO). Subsequent repeated measures ANOVAS revealed a significant increase after the stress test as compared to the baseline as well as a significant decrease after the 10 minutes relaxation phase for each of the dependent variables (see Table 1). These results suggest that the MST was effective in altering general physiologic and psychologic activation levels. Immediate IOP-reactions during MST and WDT IOP-scores during the MST and the WDT appear in Table 2. We first analyzed changes in IOP-levels before (Tl) and immediately after (T2) the stress exposition with a 2 x 2 repeated measures analysis of variance with “Test” (WDT vs. MST) as one dependent measures factor and “Time” (T1 vs. T2) as the second dependent measures factor. This analysis resulted in a nonsignificant main effect of the “Test” factor (F(1, 20) = .60, n.s.), a significant main effect of the “Time” factor (F(1,20) = 49.84; p c .OOO), and a significant

lsble 1 Cardiovascular reactions and psychological strain during Mental Stressor Test. Means, standard deviations and results of repeated measures ANOVAS (n = 22).

Time of assessment

T2

TI baseline

stress

AN0 VA

T3 relaxation

TI vs. 12 F (1,21)

l2 vs. T3

F (1, 21)

M sd

79.09 11.09

90.09 11.86

78.59 11.58

30.3’

64.1’

M sd

130.91 28.48

152.41 27.06

127.73 22.72

54.9;

44.8’

M sd

76.13 15.19

89.1 19.07

74.55 13.74

40.7*

97.1’

M sd

22.0 8.48

29.14 8.47

22.86 7.49

17.4’

29.3’

DBP = diastolic blood pressure, SBP = systolic blood pressure, HR @pm) = heart rate (beats per minute) *:p