Changes in Retinal Hemodynamics in the Optic Nerve Head of Healthy Participants Measured Using Laser Speckle Flowgraphy after a Cold Pressor Test

PURPOSE

Autoregulation of retinal vessels is stronger than that of choroidal vessels. This study aimed to use laser speckle flowgraphy to determine the time course of changes in retinal hemodynamics of healthy eyes after a cold pressor test.

METHODS

This prospective study included 44 right eyes of 44 healthy volunteers (age, 21.7 ± 5.0 years). The mean blur rate, which is a quantitative index of the relative blood flow velocity in the retina, was measured using laser speckle flowgraphy. The vessel average of mean blur rate at the optic nerve head, intraocular pressure, systolic blood pressure, diastolic blood pressure, mean blood pressure, heart rate, and ocular perfusion pressure were evaluated at baseline, immediately after the cold pressor test, and 10, 20, and 30 minutes after the test.

RESULTS

Immediately after the test (0 minutes), systolic blood pressure, diastolic blood pressure, mean blood pressure, and ocular perfusion pressure were significantly increased compared with those at baseline; however, no changes were observed at 10, 20, and 30 minutes after the test. In contrast, intraocular pressure, heart rate, and the vascular mean blur rate values at the optic nerve head did not change throughout the course of the study.

CONCLUSIONS

Sympathetic hyperactivity induced by the cold pressor test increased systemic circulatory dynamics, but not retinal circulatory hemodynamics, suggesting the involvement of vascular autoregulation.

Association between serum ALT levels and incidence of new-onset diabetes in general population of Japanese: a longitudinal observational study (ISSA-CKD)

OBJECTIVE

We aimed to clarify the relationship between serum alanine transaminase (ALT) levels and incidence of new-onset diabetes in a Japanese general population.

SETTING

Population-based retrospective cohort study using annual health check-up data for residents of Iki City, Nagasaki Prefecture, Japan.

PARTICIPANTS

A total of 5330 Japanese individuals (≥30 years old) without diabetes at baseline were analysed.

PRIMARY AND SECONDARY OUTCOME MEASURES

Serum ALT levels were determined using an enzymatic method and were classified into gender-specific quartile groups as follows: group 1 (3-16 U/L in men and 3-13 U/L in women), group 2 (17-21 U/L in men and 14-16 U/L in women), group 3 (22-29 U/L in men and 17-22 U/L in women) and group 4 (30-428 U/L in men and 23-268 U/L in women). The study outcome was the incidence of diabetes (fasting glucose ≥7.0 mmol/L, non-fasting glucose ≥11.1 mmol/L, glycated haemoglobin ≥6.5% or use of glucose-lowering therapies).

RESULTS

After an average follow-up period of 5.0 years, 279 individuals developed diabetes. The incidence rate of diabetes increased with elevation of serum ALT levels (0.7% per 100 person-years in group 1, 0.9% in group 2, 0.9% in group 3 and 1.7% in group 4) (p<0.001 for trend). This association was significant after adjustment for other risk factors including age, sex, obesity, hypertension, dyslipidaemia, smoking, current daily alcohol intake and regular exercise (p<0.001 for trend). Comparable associations were observed between men and women (p=0.459 for interaction).

CONCLUSION

Serum ALT levels were associated with future development of diabetes in the general Japanese population.

Changes in Choroidal Circulation Hemodynamics Measured Using Laser Speckle Flowgraphy after a Cold Pressor Test in Young Healthy Participants

Using laser speckle flowgraphy (LSFG), we investigated the time course of changes in choroidal circulation hemodynamics after a cold pressor test in healthy eyes. This prospective study included the right eye of 19 young healthy participants. The macular mean blur rate (MBR) was measured with LSFG. The MBR, intraocular pressure (IOP), systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), mean blood pressure (MBP), and ocular perfusion pressure (OPP) were evaluated at baseline; immediately after the test and 10, 20, and 30 min later. Immediately after the test (0 min), SBP, DBP, MBP, and OPP were significantly elevated compared with those at baseline. The macular MBR significantly increased by +10.3 ± 7.1% immediately after the test. However, there was no change after 10, 20, and 30 min in the above parameter. A significant positive correlation of the macular MBR with the SBP, MBP, and OPP was observed. In young healthy individuals, increased sympathetic activity induced by a cold pressor test increases choroidal hemodynamics in the macula along with an increase in systemic circulatory dynamics, which normalizes after 10 min. Therefore, LSFG may provide a novel approach for assessing sympathetic activity and intrinsic vascular responsiveness in the eye.

Changes in Choroidal Blood Flow by Diurnal Variation in Healthy Young Adults

Background:

Little is known about the diurnal variation in choroidal circulatory dynamics in healthy eyes.

Objective:

This study aimed to clarify the diurnal variation in choroidal circulatory hemodynamic changes in healthy participants using laser speckle flowgraphy.

Methods:

This prospective study included the left eye of 14 healthy young adults (21.9 ± 4.0 years). The mean blur rate, a quantitative index of the relative blood flow velocity, was measured by laser speckle flowgraphy. The macular mean blur rate of choroidal blood flow velocity, subfoveal choroidal thickness, intraocular pressure, systolic blood pressure, diastolic blood pressure, mean blood pressure, and ocular perfusion pressure were evaluated at eight points every 3 h over a 24-h period. In addition, differences in each parameter between daytime and night were also investigated.

Results:

Intraocular pressure, systolic blood pressure, diastolic blood pressure, mean blood pressure, ocular perfusion pressure, and macular mean blur rate were highest at 6 PM, and subfoveal choroidal thickness was thinnest at 6 PM. There was a significant positive correlation between mean blur rate and intraocular pressure, diastolic blood pressure, and mean blood pressure. Furthermore, intraocular pressure, systolic blood pressure, diastolic blood pressure, mean blood pressure, ocular perfusion pressure, and mean blur rate were significantly higher and choroidal thickness significantly lower during daytime than at night.

Conclusion:

These results suggest that choroidal circulation hemodynamics change with diurnal variations in systemic circulation involving the autonomic nervous system in healthy eyes.

Association between pulse pressure and progression of chronic kidney disease

The aim of this study was to investigate the association between pulse pressure (PP) and chronic kidney disease (CKD) progression among the general population in Japan. We conducted a population-based cohort study of the residents of Iki Island, Nagasaki, Japan, from 2008 to 2018. We identified 1042 participants who had CKD (estimated glomerular filtration rate(eGFR) < 60 mL/min/1.73 m2 or the presence of proteinuria) at baseline. Cox's proportional hazard model was used to evaluate the association between PP and progression of CKD. During a 4.66-year mean follow-up, there were 241 cases of CKD progression (incident rate: 49.8 per 1000 person-years). A significant increase existed in CKD progression per 10 mmHg of PP elevation, even when adjusted for confounding factors [adjusted hazard ratio 1.17 (1.06-1.29) p < 0.001]. Similar results were obtained even after dividing PP into quartiles [Q2: 1.14 (0.74-1.76), Q3: 1.35 (0.88-2.06), Q4: 1.87 (1.23-2.83) p = 0.003 for trend]. This trend did not change significantly irrespective of baseline systolic or diastolic blood pressures. PP remained a potential predictive marker, especially for eGFR decline. In conclusion, we found a significant association between PP and CKD progression. PP might be a potential predictive marker for CKD progression.

Comparison of Body Mass Index and Waist Circumference in the Prediction of Diabetes: A Retrospective Longitudinal Study

INTRODUCTION

Both body mass index (BMI) and waist circumference (WC) are associated with diabetes risk, and the difference between them in predictive ability for diabetes is still contentious. We conducted a population-based study to investigate and compare the association of them with diabetes by sex.

METHODS

This study included a total of 4754 subjects aged 40-80 years with no diabetes at baseline between 2008 and 2017. Using multivariate Cox proportional hazards models, we calculated hazard ratios for diabetes according to tertiles of BMI or WC. Harrell's C statistics was applied to assess and compare the predictive ability of the models using BMI and WC.

RESULTS

Both BMI and WC showed the significant positive trends with diabetes risk. In men, the extreme tertiles (BMI > 25.1 kg/m² and WC > 88.0 cm) provided 1.58-fold or 2.04-fold higher risk compared with the first tertiles (< 22.6 kg/m² and < 81.2 cm). In women, BMI > 24.4 kg/m² showed 3.28-fold higher risk than the first tertile (< 21.6 kg/m²), whereas WC ≥ 78.2 cm was more than twice as likely to suffer from diabetes as WC < 78.2 cm. BMI and WC showed a comparative performance in predicting diabetes in both sexes (P value 0.447 in men, and 0.337 in women).

CONCLUSION

Both BMI and WC showed a positive association with diabetes and offered a comparative predictive performance for diabetes in both sexes. The cut-off points, BMI 25.1 kg/m² and WC 88.0 cm in men and BMI 24.4 kg/m² and WC 78.2 cm in women, might contribute to the effective prevention strategies for diabetes.