Intrasession and Intersession Variabilities of Intraocular Pressure Measured by Noncontact Tonometer in Normal Volunteers

Purpose

Intraocular pressure (IOP) measured using a noncontact tonometer is evaluated by performing multiple measurements because IOP is affected by the ocular pulse. We investigated the relationship between value fluctuations in multiple measurements during noncontact tonometer measurements and cardiac rate.

Materials and Methods

Forty-two healthy subjects were included and IOP was measured using a noncontact tonometer. The measurement was performed three times each for the right eye and the left eye, for a total of six times. Blood pressure and cardiac rate were measured at the same time as the IOP measurement. Using repeated-measures analysis of variance, we examined whether the measured IOP and cardiac rate fluctuate throughout the day over the course of 4 days.

Results

There was a fluctuation in the IOP in a sequence only on day 1 of the four measurement days (P < 0.001). The IOP on day 1 tended to be high for the first and second measurements (P = 0.0111–0.0015). Systolic blood pressure and diastolic blood pressure did not fluctuate over the 4 days (P = 0.6247 and 0.7132), but cardiac rate was high only on day 1 (P = 0.0276).

Conclusion

The IOP on day 1 tended to be high in the first and second measurements. The IOP measured on days 2–4 did not fluctuate during the sequence of measurements. The cardiac rate measured at the same time as the IOP was high only on the first day.

Chronic social defeat stress causes retinal vascular dysfunction

PURPOSE

The roles of vascular dysfunction and chronic stress have been extensively discussed in the pathophysiology of glaucoma. Our aim was to test whether chronic stress causes retinal vascular dysfunction and therewith induces retinal ganglion cells (RGCs) loss.

METHODS

Twelve mice underwent chronic social defeat (CSD) stress, while 12 mice received control treatment only. Intraocular pressure (IOP) was measured with a rebound tonometer. Blood plasma corticosterone concentration and adrenal gland weight were used to assess stress levels. Brn-3a staining in retinas and PPD staining in optic nerve cross sections were conducted to assess the survival of RGCs and axons respectively. The ET-1 and α-SMA levels were determined in retina. Retinal vascular autoregulation, functional response to various vasoactive agents and vascular mechanics were measured using video microscopy.

RESULTS

No significant difference in IOP levels was observed during and after CSD between CSD mice and controls. CSD stress caused hypercortisolemia 2 days post-CSD. However, increased corticosterone levels went back to normal 8 months after CSD. CSD-exposed mice developed adrenal hyperplasia 3 days post-CSD, which was normalized by 8 months. RGC and axon survival were similar between CSD mice and controls. However, CSD stress caused irreversible, impaired autoregulation and vascular dysfunction of retinal arterioles in CSD mice. In addition, impaired maximal dilator capacity of retinal arterioles was observed 8 months post-CSD rather than 3 days post-CSD. Remarkably, ET-1 levels were increased 3 days post-CSD while α-SMA levels were decreased 8 months post-CSD.

CONCLUSIONS

We found that CSD stress does not cause IOP elevation, nor loss of RGCs and their axons. However, it strikingly causes irreversible impaired autoregulation and endothelial function in murine retinal arterioles. In addition, CSD changed vascular mechanics on a long-term basis. Increased ET-1 levels and loss of pericytes in retina vessels may involve in this process.

Intraocular Pressure Reactivity to Social Stressors

Abstract. A field study was carried out in an optometry clinic, aimed at assessing the role of perceived control and aversiveness of non-contact tonometry in intraocular pressure (IOP) reactivity to psychosocial stressors, and analyzing the covariation with cardiovascular and affective reactivity. Forty-four customers volunteered to participate in the study. Perceived control (self-efficacy and threat) was assessed at the onset. IOP, systolic and diastolic blood pressure, heart rate, affect, and aversiveness of the IOP measurement procedure were assessed throughout five phases with a mean duration for each phase of 9 min: arrival, optometry, baseline, stressor task (speech in public task), and recovery. The results suggest that IOP decreases over time and the stressor task induced a remarkable reactivity in all the physiological variables assessed. The interaction between self-efficacy and threat partially explains individual variability in IOP: a high threat combined with a high self-efficacy yielded higher reactivity in IOP or increased tonic values throughout the phases. The aversiveness of the measurement procedure did not affect IOP. Intraocular Pressure (IOP) is reactive to social stressors and perceived control partially explains individual variability. Cardiovascular and IOP reactivity are parallel phenomena but do not share a common regulatory mechanism.

Tear Break-Up Time and Seasonal Variation in Intraocular Pressure in a Japanese Population

PURPOSE

To evaluate seasonal variation in intraocular pressure (IOP) with and without short tear break-up time (SBUT, BUT ≤5 s) since dry eye and IOP are known to have seasonal variation.

METHODS

This study enrolled 176 patients who visited one of six eye clinics, in Japan, four times for IOP measurement, in every season. The mean patient age was 67.9 years, including 79 males. Participants were divided into four groups based on the presence of glaucoma and/or SBUT and we compared the seasonal variation in IOP (winter and summer) among the four groups.

RESULTS

The IOP (mmHg) in winter and summer, respectively, was 12.8 ± 3.7 and 12.8 ± 3.1 for non-glaucoma patients without SBUT (n = 47, p = 0.964), 14.8 ± 3.4 and 13.3 ± 3.4 for non-glaucoma patients with SBUT (n = 57, p < 0.001), 14.3 ± 3.2 and 14.1 ± 3.4 for glaucoma patients without SBUT (n = 36, p = 0.489), and 13.3 ± 3.0 and 11.6 ± 2.9 for glaucoma with SBUT (n = 36, p < 0.001). Seasonal variation was largest across the seasons in the glaucoma with the SBUT group, and the magnitude of seasonal variation correlated with BUT (β = 0.228, p = 0.003).

CONCLUSIONS

Seasonal variation tended to be larger in patients with SBUT than those without SBUT.

Intraocular Pressure as an Indicator of the Level of Induced Anxiety in Basketball

SIGNIFICANCE

Our data demonstrate that intraocular pressure (IOP) is sensitive to anxiety manipulation in sport scenarios, specifically in a basketball free throw task. The present outcomes may be of special relevance because of its practical advantages for the objective control of athletes' anxiety levels.

PURPOSE

Athletes experience high levels of anxiety during sport competition, and IOP has demonstrated to reflect autonomous nervous system changes during mentally demanding situations. We tested whether different levels of induced anxiety during basketball free throw shooting alter IOP.

METHODS

We followed a repeated-measures design to test the effects of anxiety-induced manipulation during basketball free throw shooting on IOP, shooting performance, and perceived anxiety. Eighteen amateur basketball players performed three experimental sessions consisting of 100 free throws each. However, we gave three different instructions to participants regarding the score assigned to each free throw, allowing us to manipulate the level of induced anxiety (low, medium, and high).

RESULTS

Confirming a successful anxiety manipulation, basketball players reported more perceived anxiety with higher levels of induced anxiety (P < .001, η = 0.37). Our data show that higher levels of induced anxiety provoke an acute IOP rise (P < .001, η = 0.44), with the low-, medium-, and high-anxiety-induced conditions promoting an average IOP rise of 0.21, 1.63, and 18.46%, respectively. Also, there was a linear IOP rise over time in the high-anxiety-induced condition (r = 0.82). Nevertheless, we found no effect of anxiety-induced manipulation on basketball free throw performance (P = .93).

CONCLUSIONS

Intraocular pressure is sensitive to anxiety-induced manipulation during basketball free throw shooting, showing an increase in parallel with accumulated anxiety. Based on these findings, IOP may be considered a promising tool for the assessment of the level of anxiety in certain sport situations. Future studies are required to explore the generalizability of these results in other scenarios with different physical and mental demands.

Acute Stress Increases Intraocular Pressure in Nonhuman Primates

Purpose

To quantify intraocular pressure (IOP) change and time course during stressful activity.

Study Design

Experimental Study.

Subjects

Three nonhuman primates (NHPs).

Methods

Bilateral IOP and aortic blood pressure (BP) were recorded continuously, then averaged for periods of 8-30 seconds before, during, and after a common anesthetic induction procedure (cage squeeze followed by intramuscular injection). Experiments were repeated four times in each NHP.

Main Outcome Measures

IOP, BP, and heart rate (HR) change during an anesthetic induction procedure.

Results

IOP, mean arterial pressure (MAP), and HR increased rapidly and significantly by 27%, 38%, 34%, respectively, in anticipation of anesthetic induction (Figure; p<0.05). IOP rose ~10% within 10 seconds of hearing the technician enter the outer anteroom door, and reached its maximum within ~1 minute of first anticipating human contact. IOP fell to below baseline levels within 1 minute after anesthetic induction.

Conclusions

IOP increases rapidly and significantly in response to stressful situations in the nonhuman primate.

Intraocular pressure is sensitive to cumulative and instantaneous mental workload

We used a repeated-measures design to assess the impact of mental-task complexity on intraocular pressure (IOP). Fourteen participants performed three continuous 11-min blocks of a mental-workload task (3-back) and an oddball version of this task. Also, heart-rate variability (HRV), cognitive-performance scores, and subjective measure of mental load (NASA-TLX) were determined. IOP was taken before each block and afterwards as well as after recovery from mental tasks. We found that IOP increased during heavy mental workloads (p < 0.01). Consistent with this finding, the autonomic control (HRV) and the cognitive performance were significantly lower (p < 0.045, and p < 0.01, respectively), and the NASA-TLX scores were higher during the 3-back task (p < 0.01). We conclude that IOP is sensitive to mental workload, and it could provide a novel neuroergonomic tool to assess mental workload. Our study highlights a potential association between IOP and the nervous system's state of activation.

Elevation of intraocular pressure in glaucoma patients after automated visual field testing

PURPOSE

To examine whether automated visual field (VF) testing may exert a short-term influence on subsequent intraocular pressure (IOP) measurement during the same visit.

METHODS

We reviewed patients with primary open-angle glaucoma whose most recent visit occurred at a major academic institution from July to December 2009 and who had 3 visits without intervening changes in glaucoma management within the previous 5 years. Exclusion criteria were patient admittance of nonadherence with medical therapy and documented difficulty of IOP measurement. One hundred nine right eyes from 109 patients were included. IOP obtained within 30 minutes after VF testing was compared with IOP from the previous and next visits without VF testing. Subgroup analyses included the role of reliability of VF test performance, surgical versus medical IOP control, and different topical medications.

RESULTS

The average IOP measured after VF testing was 14.9 ± 4.7 mm Hg, higher than both the previous (13.7 ± 4.4 mm Hg, P < 0.001) and next visits without VF examination (13.8 ± 4.4 mm Hg, P < 0.001). A total of 22.9% of patients experienced a more than 20% increase of IOP. Eyes with surgical control had less IOP elevation than eyes with medical control (3.1% ± 15.9% vs. 11.7% ± 17.4%, P = 0.009). Users of β-blockers or α-2-agonists had less IOP elevation than eyes controlled with prostaglandins or carbonic anhydrase inhibitors (0.9% ± 15.1% vs. 9.0% ± 12.3%, P = 0.030).

CONCLUSIONS

This retrospective study suggests that patients with primary open-angle glaucoma experience a small and transient increase in IOP after VF testing and that this effect may be lower after surgical pressure control.

The relationship between psychosocial stress, age, BMI, CRP, lifestyle, and the metabolic syndrome in apparently healthy subjects

The aim of this cross-sectional study was to examine the factors which may be associated with the metabolic syndrome by exploring the relationship between psychosocial stress, age, body mass index (BMI), C-reactive protein (CRP), lifestyle factors, and the components of the metabolic syndrome, such as glycated hemoglobin (HbA1c), fasting blood sugar (FBS), body fat percentage, and triglyceride concentration, among apparently healthy subjects. Psychosocial stress was measured by the use of the inventory to measure psychosocial stress (IMPS). One thousand four hundred and ninety-nine people out of 1,941 public school workers admitted to a hospital for a medical check-up responded to the IMPS, yielding a response rate of 77.2%. A total of 1,201 workers excluding 298 who were taking medication for various diseases were analyzed with the use of hierarchical multiple regression models. It was found that IMPS-measured stress score, age, BMI, and smoking habit were associated with an increase in glycated hemoglobin among men, while alcohol consumption was associated with a decrease in glycated hemoglobin. Stress score, age, BMI, and alcohol consumption were found to be associated with an increase in FBS among men, while smoking and exercise habits were associated with a decrease in FBS. CRP was found to be associated with an increase in body fat percentage among men, though stress score was not associated with an increase in body fat percentage. Stress score, age, and BMI were associated with an increase in triglyceride concentration among women. The findings of the present study seem to be in line with the hypothesis that psychosocial stress plays an important role in developing the metabolic syndrome, which may be associated with inflammatory processes in the vascular wall, resulting in atherosclerosis and cardiovascular disease.

Is elevated noradrenaline an aetiological factor in a number of diseases?

1 Here I put forth the hypothesis that noradrenaline (NA), which is a signalling molecule in the brain and sympathetic nervous system (SNS), is an aetiological factor in a number of diseases. 2 In a previous paper (Fitzgerald, Int. J. Cancer, 124, 2009, 257), I examined evidence that elevated NA is a factor in various types of cancer. Here I extend the argument to several other diseases, including diabetes mellitus, open-angle glaucoma, osteoarthritis and rheumatoid arthritis and asthma. 3 The principal hypothesis is that, largely as a result of genetics, elevated noradrenergic tone in the SNS predisposes a large number of individuals to a broad range of diseases. 4 For each of the above five diseases, I briefly examine the following four lines of evidence to assess the hypothesis: i) whether pharmacological studies in rodents that manipulate NA levels or receptors affect these diseases; ii) whether pharmacological manipulation of NA in humans affects these diseases; iii) whether bipolar disorder, excessive body weight, and hypertension, which may all three involve elevated NA, tend to be comorbid with these diseases and iv) whether psychological stressors tend to cause or exacerbate these conditions, since psychological stress is associated with increased release of NA. 5 The four lines of evidence tend to support the hypothesis.

The relationship between premenstrual symptoms, menstrual pain, irregular menstrual cycles, and psychosocial stress among Japanese college students

The aim of this study was to examine the relationship between menses-associated health problems of women, such as premenstrual symptoms, menstrual pain and irregular menstrual cycles, and psychosocial stress. A cross-sectional study was conducted among Japanese college students, measuring psychosocial stress levels by means of IMPS (The Inventory to Measure Psychosocial Stress). A total of 264 female students (mean age 19.4 years), who were invited to participate in the study in October 2007, completed the questionnaire, which dealt with anthropometric data, lifestyle, menstrual history, and menstrual health status. Forty-three students were excluded due to missing data, and the remaining 221 were analyzed. The proportions of students who reported premenstrual symptoms, menstrual pain, and the experience of irregular menstrual cycles were 79%, 79%, and 63%, respectively. Students who reported premenstrual symptoms, menstrual pain, and the experience of irregular menstrual cycles had higher stress scores than those who did not. Multiple logistic regression analyses were used to identify independent factors associated with having premenstrual symptoms, menstrual pain, and the experience of irregular menstrual cycles. Stress score, heavy menstrual flow, and menstrual pain were significant predictors for premenstrual symptoms, while age at menarche and having premenstrual symptoms were significant predictors for menstrual pain. Both stress score and body mass index were found to be significant predictors for having experienced irregular menstrual cycles. The results suggest that psychosocial stress is independently associated with premenstrual symptoms and the experience of irregular menstrual cycles among college students, implying that changes in the functional potentiality of women as a result of stress are related with changes in their menstrual function.