Korean J Ophthalmol > Volume 38(2); 2024 > Article
Sato, Hashimoto, Sakamoto, Nakano, Yoshimura, Yamanokuchi, and Yoshitomi: Changes in Retinal Hemodynamics in the Optic Nerve Head of Healthy Participants Measured Using Laser Speckle Flowgraphy after a Cold Pressor Test

Abstract

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.

Although autoregulation varies in every vascular system, retinal vessels are more autoregulatory than choroidal vessels [1]. Changes in ocular perfusion pressure (OPP) have been shown to increase retinochoroidal blood flow immediately after dynamic exercise; however, this increase in blood flow was more sustained in the choroid-retina than in the retina. This difference may be related to the stronger blood flow autoregulation mechanism in the retina compared to that in the choroid [2]. Furthermore, it has been reported that blood flow in the optic nerve head (ONH) is autoregulated in response to fluctuations in intraocular pressure (IOP) and systemic blood pressure (BP) [3].
Cold pressor tests assess sympathetic responses in systemic circulatory dynamics [4-8]. This examination is used for screening hypertension and can predict future hypertension based on cardiovascular response [4,5]. Recently, a study that examined the vascular reactivity of the retina and choroid using functional optical coherence tomography (OCT) found that the vascular perfusion density of healthy individuals after a cold pressor test decreased in the choroid but remained unchanged in the retina [6]. Additionally, the choroidal morphology of healthy participants was quantitatively evaluated using enhanced depth imaging OCT and the cold pressor test; the results showed a significant decrease in subfoveal choroidal thickness (SFCT) after the test, and the decreased SFCT takes longer than other measures of circulation such as systolic BP (SBP), diastolic BP (DBP), mean BP (MBP), and OPP [8].
Laser speckle flowgraphy (LSFG) noninvasively measures the ocular blood flow and can quantitatively evaluate circulatory hemodynamics using the mean blur rate (MBR), which is a relative value of the blood flow velocity [9]. The wavelength of the diode laser used in LSFG is 830 nm (near-infrared light). The measurement light is irradiated onto moving erythrocytes within the retina and choroid. The resulting speckle pattern, formed by the interference of the scattered light, is then analyzed. To clarify, the faster the movement of erythrocytes, the lower the speckle contrast becomes [10,11]. The MBR is calculated from the change in the degree of blurring, which is proportional to the inverse square of the speckle contrast, and is used as a quantitative measure of relative blood flow velocity that has no units of quantity. If erythrocytes move faster, the speckle motion accelerates, resulting in increased blurring and an elevated MBR value. LSFG can create a two-dimensional color map based on blood flow velocity data, which is useful for confirming changes in the normal eye, monitoring the onset and progression of disease, and for follow-up observations [12-25]. The macular MBR reflects choroidal blood flow caused by the absence of the inner retinal layer at the fovea [12-21], whereas the ONH provides three MBRs: vessel average (MBR-V), tissue average (MBR-T), and overall average (MBR-A) [21-25].
Several studies have explored the hemodynamics of ONH using LSFG. The ONH blood flow has been reported to be highly autoregulated with its own diurnal variation [20], correlates with postmenstrual age in normal neonates [22], and does not differ between the left and right eye [23]. In Vogt-Koyanagi-Harada disease associated with anterior ischemic optic neuropathy, retinal blood flow velocity in the ONH decreases and choroidal blood flow velocity in the macula increases during the course of the disease, indicating that LSFG is a useful tool for evaluating the circulatory dynamics in the ONH and choroid [21]. Additionally, in patients with optic disc drusen, the blood flow velocity in the ONH is significantly reduced compared to that in normal eyes, and a significant correlation is observed between blood flow velocity and visual field defects [24]. Furthermore, in nasal optic disc hypoplasia patients (NOH), the MBR and circumpapillary retinal nerve fiber layer thickness ratios in NOH eyes significantly reduced compared to that in control eyes. Furthermore, a significantly positive correlation has been detected between MBR and circumpapillary retinal nerve fiber layer thickness in the nasal region [25]. Thus, LSFG is suitable for evaluating changes in the ocular hemodynamics of healthy individuals and those with various retinochoroidal diseases.
The autonomic nervous system (sympathetic nervous system) contracts blood vessels and increases BP in response to cold stimuli during winter [26,27]. The winter climate has been shown to affect the parameters associated with the increased risks of arteriosclerosis, vein occlusion, and hypertension [28,29]. In Japan, retinal vein occlusion (RVO) is a prevalent ocular disease with increasing incidence rates during the winter season, and hypertension is identified as one of its risk factors [30]. Furthermore, a study using LSFG has shown that in patients with RVO, the blood flow velocity of the ONH is reduced in the acute phase of the disease [31]. In addition, it has been reported that blood flow velocity in the ONH is also decreased in glaucoma. The meta-analysis revealed that MBR-V, MBR-T, and MBR-A are significantly decreased in glaucomatous eyes and there are significant differences in MBR based on the type of glaucoma [32]. Therefore, the consequences of these changes in ONH circulation dynamics may contribute to vascular autoregulation as a triggering factor for ocular disease.
We recently reported that macular MBR, an indicator of choroidal blood flow velocity, increases immediately after the cold pressor test [12]; however, changes in retinal vessel blood flow in the ONH as observed through LSFG after sympathetic nerve hyperactivity induced by the cold pressor test have not been assessed. During this study, we investigated vascular autoregulation of the ONH by measuring the time course of the change in the hemodynamics of the ONH after a cold pressor test using LSFG.

Materials and Methods

Ethics statement

This study was approved by the Ethics Committee of the Fukuoka International University of Health and Welfare (No. 20-fiuhw-022) and adhered to the tenets of the Declaration of Helsinki. Written informed consent was obtained from all participants after the nature and possible consequences of the study were explained to them.

Study design and participants

This prospective study included 44 right eyes of 44 healthy volunteers (18 men and 26 women) with no ophthalmic, cardiovascular, or systemic diseases. Their mean age was 21.7 ± 5.0 years (range, 18-43 years). All participants had best-corrected visual acuity of ≥20 / 20. Each participant underwent examinations of the IOP, SBP, DBP, heart rate (HR), and LSFG. All measurements were conducted between 12:00 and 15:00 to account for the effects of diurnal variation [14,20], and participants refrained from smoking and engaging in exercise for at least 2 hours prior to the test and took rest for 10 minutes in a quiet room. In addition, these examinations were conducted at room temperature (24 ± 1 °C) with a humidity level of 47% ± 3% [12-15].

Cold pressor test

During the cold pressor test, the right hand was immersed up to the wrist in ice water with a temperature of approximately 1 °C for 30 seconds [6,8,12]. The IOP, BP, HR, and LSFG measurements were assessed at baseline, immediately after the test (0 minutes), and 10, 20, and 30 minutes after the test. At all measurement points, BP and HR were measured first, LSFG was performed second, followed by IOP testing. All examinations were performed with the participant in the sitting position, and each experimental session was completed within 3 minutes. Additionally, the participants were asked not to smoke or engage in exercise for at least 2 hours before the examinations, and they were allowed to rest for 10 minutes in a quiet room.

Retinal circulation measurements

The LSFG measurements were performed using the LSFG-NAVI (Softcare Ltd) to quantitatively assess the ONH blood flow velocity, and it has no unit of quantity. The LSFG results of all eyes were examined three times at each time point. A circular band was set on the color map of the ONH (Fig. 1A). At follow-up, each circle was automatically set using LSFG Analyzer ver. 3.7.0.4 (Softcare Ltd) at the same site where the circle was set at baseline. This software can evaluate MBR-V (white areas) and MBR-T (black areas), and MBR-A (overall average) separately using an automated definitive threshold. In order to evaluate the change in mean MBR-V, MBR-T, and MBR-A (Fig. 1B), we utilized the rates of change in each mean MBR value and compared them to the initial baseline values (defined as 100%) [12,13,16-19,22].

Hemodynamics

The IOP, BP and HR of all participants were measured at baseline, immediately after the cold pressor test, and 10, 20, and 30 minutes after the test. The IOP measurement was performed with a noncontact tonometer (NT-530, Nidek Co Ltd). Hemodynamics of the eye depend on the BP and IOP and are measured based on an indicator called OPP, which reflects systemic circulatory dynamics. The OPP was calculated using the IOP and BP values. The MBP was calculated using the SBP and DBP.
MBP=DBP+1/3(SBP-DBP)OPP=2/3MBP-IOP

Statistical analysis

The Friedman test and Scheffé test were performed to examine sequential changes in the IOP, SBP, DBP, MBP, HR, OPP, and MBRs (MBR-V, MBR-T, and MBR-A). The same statistical analyses were also performed separately for men and women groups. For all tests, p < 0.05 indicated statistical significance.

Results

IOP, HR, and OPP data

Changes in the IOP and other systemic factors are summarized in Table 1 and Supplementary Tables 1 and 2. The IOP and HR did not change throughout the course of the study (Friedman test; IOP, p = 0.273; HR, p = 0.416). The changes in the OPP are presented in Table 1 and Supplementary Table 1. The mean OPP was 40.3 ± 5.0 mmHg at baseline, 44.3 ± 5.5 mmHg at 0 minutes, 40.9 ± 4.8 mmHg at 10 minutes, 40.8 ± 4.9 mmHg at 20 minutes, and 41.1 ± 5.3 mmHg at 30 minutes after the cold pressor test. The mean OPP value at 0 minutes was significantly higher than the baseline value (p < 0.001); however, no significant difference was observed at 10, 20, and 30 minutes relative to the baseline data. Separate investigations of the male and female groups (Friedman test) showed no significant changes in IOP (male group, p = 0.111; female group, p = 0.399) and HR (male group, p = 0.605; female group, p = 0.575), while OPP was significantly elevated only immediately after cold stimulation in both the groups (male group, p = 0.002; female group, p = 0.005) (Tables 2, 3).

SBP, DBP, and MBP data

The changes in the SBP, DBP, and MBP are presented in Table 1 and Supplementary Table 1. The mean SBP was 108.0 ± 10.6 mmHg at baseline, 113.9 ± 11.1 mmHg at 0 minutes, 108.0 ± 10.7 mmHg at 10 minutes, 107.5 ± 11.0 mmHg at 20 minutes, and 108.1 ± 10.5 mmHg at 30 minutes after the cold pressor test. The mean SBP value at 0 minutes was significantly higher than the baseline value (p < 0.001); however, there was no significant difference at 10 minutes (p = 0.998), 20 minutes (p = 1.000), and 30 minutes (p = 1.000) relative to the baseline data. The mean DBP was 66.2 ± 7.1 mmHg at baseline, 72.0 ± 8.3 mmHg at 0 minutes, 66.7 ± 6.7 mmHg at 10 minutes, 66.7 ± 7.0 mmHg at 20 minutes, and 67.1 ± 7.7 mmHg at 30 minutes after the cold pressor test. The mean DBP value at 0 minutes was significantly higher than the baseline value (p < 0.001); however, no significant differences were observed at 10 minutes (p = 1.000), 20 minutes (p = 0.997), and 30 minutes (p = 0.993) relative to the baseline data. The mean MBP was 80.2 ± 7.8 mmHg at baseline, 85.9 ± 8.3 mmHg at 0 minutes, 80.5 ± 7.4 mmHg at 10 minutes, 80.3 ± 7.5 mmHg at 20 minutes, and 80.8 ± 8.2 mmHg at 30 minutes after the cold pressor test. The mean MBP value at 0 minutes was significantly higher than the baseline value (p < 0.001); however, no significant differences were observed at 10 minutes (p = 0.999), 20 minutes (p = 0.962), and 30 minutes (p = 0.987) relative to the baseline data. In addition, the male group demonstrated significant increases in DBP (p = 0.021) and MBP (p = 0.016), whereas the female group exhibited significant elevations in SBP (p < 0.001), DBP (p = 0.039), and MBP (p = 0.005) only immediately after the cold stimulus (Tables 2, 3).

Changes in the MBR-V, MBR-T, and MBR-A of the ONH

The changes in MBRs are shown in Table 1 and Supplementary Table 1. The average MBR-V values of the ONH at baseline, immediately after the cold pressor test (0 minutes), and at 10, 20, and 30 minutes after the test were 44.3 ± 5.1, 44.3 ± 4.9, 45.2 ± 5.2, 44.6 ± 5.3, and 45.1 ± 5.4, respectively. The average MBR-T values of the ONH at baseline, immediately after the cold pressor test (0 minutes), and at 10, 20, and 30 minutes after the test were 13.3 ± 2.3, 13.4 ± 2.2, 13.6 ± 2.2, 13.3 ± 2.1, and 13.5 ± 2.0, respectively. The average MBR-A values of the ONH at baseline, immediately after the cold pressor test (0 minutes), and at 10, 20, and 30 minutes after the test were 25.0 ± 3.4, 24.8 ± 3.4, 25.1 ± 3.4, 25.1 ± 3.4, and 25.3 ± 3.2, respectively. The MBR values of the ONH did not change throughout the course of the study (Friedman test: MBR-V, p = 0.447; MBR-T, p = 0.258; MBR-A, p = 0.750). Additionally, MBR-V, MBR-T, and MBR-A did not change significantly during the course of the study for either the male group (Friedman test; p = 0.138, p = 0.157, and p = 0.930, respectively) or the female group (Friedman test; p = 0.852, p = 0.873, and p = 0.707, respectively) (Tables 2, 3).

Discussion

In the present study, we used as a quantitative measured changes in the MBRs of the ONH after the cold pressor test using LSFG. The SBP, DBP, MBP, and OPP increased significantly immediately after the test; however, no further changes were observed after 10 minutes. In contrast, the retinal blood flow velocity in the ONH did not change throughout the course of the study. The results were almost similar for the investigation of male and female groups when analyzed separately.
The diurnal variations of the macular MBR of choroidal blood velocity are significant, with the peak at 6:00 pm, when the sympathetic nervous system is active [14,20], and the MBR is significantly positively correlated with DBP, MBP, and OPP [20]. Recently, it was observed that healthy women with normal menstrual cycles had a more active sympathetic nervous system during the luteal phase compared with that during the follicular phase, suggesting that macular MBR increases in response to increased systemic hemodynamics, and the MBR exhibit a significant positive correlation with changes in DBP and MBP [19]. In addition, the sympathetic activity caused by physiological and psychological stress has been suggested to increase in winter, and choroidal blood flow velocity increases with increased IOP, BP, and OPP [15]. Furthermore, the macular MBR significantly increased by approximately 10% immediately after the cold pressor test, and a significant positive correlation is observed between the MBR and the SBP, MBP, and OPP [12].
However, interestingly, dynamic exercise changes the OPP and produces increased tissue blood flow to the retina during the immediate postexercise period, whereas blood flow increases more persistently in the choroid-retina [2]. It has also been reported that the ONH blood flow has its own diurnal variation because of strong autoregulation, whereas the choroidal blood flow is more likely affected by systemic circulatory factors because of poor autoregulation [20]. A recent study that examined the vascular reactivity of the retina and choroid using functional OCT showed that the vascular perfusion density of healthy individuals after the cold pressor test decreased in the choroid but remained unchanged in the retina. Furthermore, the choroidal vascular perfusion density has a strong inverse correlation with integrated muscle sympathetic nerve activity [7]. Additionally, it has been reported that blood flow in the ONH is autoregulated in response to fluctuations in systemic BP [3]. The difference in blood flow regulation in the retina and choroid may be related to the stronger autoregulatory mechanism of blood flow in the retina [2]. In the present study, the retinal blood flow velocity in the ONH increased immediately after the cold pressor test, when the activity of the sympathetic nervous system was high; accordingly, the BP and OPP also increased. These results indicate that sympathetic hyperactivity attributable to cold stimulation changes systemic circulatory hemodynamics but does not affect the retinal vessels.
Numerous studies have investigated the association between ONH and MBR in diseases that cause retinal circulatory disturbances. In the acute phase of central RVO, a pathology involving retinal circulatory disturbance, MBR-V, MBR-T, and MBR-A of ONH are significantly decreased [31]. Furthermore, abnormal ocular blood flow has recently been hypothesized as an important factor in visual field defects in glaucoma. A meta-analysis evaluating the diagnostic value of LSFG in glaucoma suggests that glaucoma is closely related to changes in ONH blood flow, as MBR-A, MBR-T, and MBR-V are reduced in glaucomatous eyes [32].
The present study has some limitations. First, the circulatory dynamics of the ONH were evaluated only through LSFG; however, OCT angiography should also be used for a detailed evaluation. Furthermore, although only the circulatory dynamics of the ONH were determined in this study, they should be measured using OCT C-scan to examine the relationship with the morphology of the ONH. Therefore, further studies are warranted to explore hemodynamic and morphological changes in the ONH after cold pressor test using different modalities. Second, BP varies with time of day, age, sex, season, stress, hormones, etc., and should be studied in detail under different conditions. Third, we performed the hand cold pressor test as the stimulation method in the present study; however, to enhance the applicability of our findings, it is necessary to measure under various stimulation conditions, encompassing whole body and foot cold pressor tests, as well as exercise stress tests.
In conclusion, sympathetic hyperactivity induced by the cold pressor test increased systemic circulatory dynamics, but not retinal circulatory hemodynamics, of healthy individuals, thus suggesting the involvement of vascular autoregulation. In the future, the findings from this study may provide basic data for future investigations of the relationship between diseases involving these retinal circulation disorders and the autoregulation of the ONH.

Acknowledgements

None.

Notes

Conflicts of Interest: None.

Funding: This work was financially supported by the Grants-in-Aid for Scientific Research (KAKENHI) program (No. JP20K19698 and JP23K10818), through the Japan Society for the Promotion of Science.

Supplementary Materials

Supplementary materials are available from https://doi.org/10.334/kjo.2023.0063.

Supplementary Table 1.

Characteristics and changes in ocular biometric parameters at baseline and at 0, 10, 20, and 30 minutes after the cold pressor test in healthy participants (n = 44)
kjo-2023-0063-Supplementary-Table-1.pdf

Supplementary Table 2.

Changes in systemic factors at baseline and at 0, 10, 20, 30 minutes after the cold pressor test in healthy participants (n = 44)
kjo-2023-0063-Supplementary-Table-2.pdf

References

1. Delaey C, Van De Voorde J. Regulatory mechanisms in the retinal and choroidal circulation. Ophthalmic Res 2000;32:249-56.
crossref pmid pdf
2. Okuno T, Sugiyama T, Kohyama M, et al. Ocular blood flow changes after dynamic exercise in humans. Eye (Lond) 2006;20:796-800.
crossref pmid pdf
3. Okuno T, Oku H, Sugiyama T, et al. Evidence that nitric oxide is involved in autoregulation in optic nerve head of rabbits. Invest Ophthalmol Vis Sci 2002;43:784-9.
pmid
4. Hines EA Jr, Brown GE. The cold pressor test for measuring the reactibility of the blood pressure: data concerning 571 normal and hypertensive subjects. Am Heart J 1936;11:1-9.
crossref
5. Wood DL, Sheps SG, Elveback LR, Schirger A. Cold pressor test as a predictor of hypertension. Hypertension 1984;6:301-6.
crossref pmid
6. Budidha K, Kyriacou PA. Photoplethysmography for quantitative assessment of sympathetic nerve activity (SNA) during cold stress. Front Physiol 2019;9:1863.
crossref
7. Jendzjowsky NG, Steinback CD, Herman RJ, et al. Functional-optical coherence tomography: a non-invasive approach to assess the sympathetic nervous system and intrinsic vascular regulation. Front Physiol 2019;10:1146.
crossref pmid pmc
8. Umemoto R, Hashimoto Y, Imabayashi S, Yoshitomi T. Changes in choroidal thickness in healthy participants after induction of sympathetic hyperactivity using the cold pressor test. Graefes Arch Clin Exp Ophthalmol 2023;261:585-7.
crossref pmid pdf
9. Nagahara M, Tamaki Y, Tomidokoro A, Araie M. In vivo measurement of blood velocity in human major retinal vessels using the laser speckle method. Invest Ophthalmol Vis Sci 2011;52:87-92.
crossref pmid
10. Tamaki Y, Araie M, Kawamoto E, et al. Noncontact, two-dimensional measurement of retinal microcirculation using laser speckle phenomenon. Invest Ophthalmol Vis Sci 1994;35:3825-34.
pmid
11. Isono H, Kishi S, Kimura Y, et al. Observation of choroidal circulation using index of erythrocytic velocity. Arch Ophthalmol 2003;121:225-31.
crossref pmid
12. Imabayashi S, Hashimoto Y, Ishimaru Y, et al. Changes in choroidal circulation hemodynamics measured using laser speckle flowgraphy after a cold pressor test in young healthy participants. Tomography 2023;9:790-7.
crossref pmid pmc
13. Kuwahara F, Hashimoto Y, Toh N, et al. Parasympathetic dominance decreases the choroidal blood flow velocity measured using laser speckle flowgraphy. Cureus 2023;15:e46996.
crossref pmid pmc
14. Hashimoto Y, Ishimaru Y, Chiyozono M, et al. Changes in choroidal blood flow by diurnal variation in healthy young adults. Open Ophthalmol J 2023;17:e187436412301300..
crossref pdf
15. Hashimoto Y, Igawa R, Sakai Y, et al. Seasonal variation of choroidal thickness and circulation in young, healthy participants. Acta Ophthalmol 2023;101:708-9.
crossref pmid pdf
16. Saito M, Saito W, Hashimoto Y, et al. Macular choroidal blood flow velocity decreases with regression of acute central serous chorioretinopathy. Br J Ophthalmol 2013;97:775-80.
crossref pmid
17. Hirooka K, Saito W, Namba K, et al. Relationship between choroidal blood flow velocity and choroidal thickness during systemic corticosteroid therapy for Vogt-Koyanagi-Harada disease. Graefes Arch Clin Exp Ophthalmol 2015;253:609-17.
crossref pmid pdf
18. Hashimoto Y, Saito W, Saito M, et al. Decreased choroidal blood flow velocity in the pathogenesis of multiple evanescent white dot syndrome. Graefes Arch Clin Exp Ophthalmol 2015;253:1457-64.
crossref pmid pdf
19. Haneda M, Hashimoto Y, Mishima A, et al. Changes in choroidal circulation hemodynamics during the menstrual cycle in young, healthy women. PLoS One 2022;17:e0270501.
crossref pmid pmc
20. Iwase T, Yamamoto K, Ra E, et al. Diurnal variations in blood flow at optic nerve head and choroid in healthy eyes: diurnal variations in blood flow. Medicine (Baltimore) 2015;94:e519..
pmid pmc
21. Matsumoto T, Itokawa T, Shiba T, et al. Ocular blood flow values measured by laser speckle flowgraphy correlate with the postmenstrual age of normal neonates. Graefes Arch Clin Exp Ophthalmol 2016;254:1631-6.
crossref pmid pmc pdf
22. Yamashita Y, Hashimoto Y, Namba K, et al. Optic nerve head microcirculation in eyes with vogt-koyanagi-harada disease accompanied by anterior ischemic optic neuropathy. Case Rep Ophthalmol 2021;12:899-908.
crossref pmid pmc pdf
23. Kobayashi T, Shiba T, Okamoto K, et al. Characteristics of laterality in the optic nerve head microcirculation obtained by laser speckle flowgraphy in healthy subjects. Graefes Arch Clin Exp Ophthalmol 2022;260:2799-805.
crossref pdf
24. Wagstrom J, Malmqvist L, Hamann S. Optic nerve head blood flow analysis in patients with optic disc drusen using laser speckle flowgraphy. Neuroophthalmology 2020;45:92-8.
crossref pmid
25. Hasegawa Y, Hashimoto Y, Shinmei Y, Ishida S. Optic nerve head microcirculation in congenital nasal optic disc hypoplasia. Graefes Arch Clin Exp Ophthalmol 2020;258:211-3.
crossref pmid pdf
26. Modesti PA. Season, temperature and blood pressure: a complex interaction. Eur J Intern Med 2013;24:604-7.
crossref pmid
27. Miersch A, Vogel M, Gausche R, et al. Influence of seasonal variation on blood pressure measurements in children, adolescents and young adults. Pediatr Nephrol 2013;28:2343-9.
crossref pmid pdf
28. Wittert GA, Or HK, Livesey JH, et al. Vasopressin, corticotrophin-releasing factor, and pituitary adrenal responses to acute cold stress in normal humans. J Clin Endocrinol Metab 1992;75:750-5.
crossref pmid
29. Mizuno K, Yamashita T, Ohara K, et al. Differences in seasonal incidence and risk factors of cardio-cerebrovascular events in sample of workers who underwent a health check-up. J Jpn Soc Ningen Dock 2017;31:668-74.
30. Matsuzawa M, Sakanishi Y, Ebihara N. Seasonal variation in the occurrence of retinal vein occlusion: a 4-year cross-sectional study. BMC Ophthalmol 2020;20:265.
crossref pmid pmc pdf
31. Hikage F, Furuhashi M, Ida Y, et al. Fatty acid-binding protein 4 is an independent factor in the pathogenesis of retinal vein occlusion. PLoS One 2021;16:e0245763.
crossref pmid pmc
32. Gu C, Li A, Yu L. Diagnostic performance of laser speckle flowgraphy in glaucoma: a systematic review and meta-analysis. Int Ophthalmol 2021;41:3877-88.
crossref pmid pdf

Fig. 1
Analysis of retinal circulation in the optic nerve head using laser speckle flowgraphy (LSFG). (A) Composite color map of the mean blur rate (MBR) created using LSFG. A circular band indicates the margin (inferior [I], superior [S], nasal [N], and temporal [T] sectors) of the optic nerve head. (B) LSFG Analyzer ver. 3.7.0.4 (Softcare Ltd) can distinguish the vessels using the automated definitive threshold. The white area represents the blood flow velocity in the retinal vessels, which is the vessel average MBR.
kjo-2023-0063f1.jpg
Table 1
Changes in ocular biometric parameters and systemic factors at baseline and at 0, 10, 20, and 30 minutes after the cold pressor test (n = 44)
Variable Baseline After the cold pressor test p-value


0 min 10 min 20 min 30 min Friedman test Scheffé test

0 min 10 min 20 min 30 min
IOP (mmHg) 13.1 ± 2.7 12.9 ± 2.7 12.7 ± 2.6 12.6 ± 2.6 12.7 ± 2.7 0.273 0.995 0.608 0.647 0.547
SBP (mmHg) 108.0 ± 10.6 113.9 ± 11.1* 108.0 ± 10.7 107.5 ± 11.0 108.1 ± 10.5 <0.001 <0.001 0.998 1.000 1.000
DBP (mmHg) 66.2 ± 7.1 72.0 ± 8.3* 66.7 ± 6.7 66.7 ± 7.0 67.1 ± 7.7 <0.001 <0.001 1.000 0.997 0.993
MBP (mmHg) 80.2 ± 7.8 85.9 ± 8.3* 80.5 ± 7.4 80.3 ± 7.5 80.8 ± 8.2 <0.001 <0.001 0.999 0.962 0.987
HR (bpm) 82.4 ± 12.4 81.3 ± 12.0 82.8 ± 11.0 82.0 ± 11.3 82.0 ± 11.9 0.416 0.987 0.775 1.000 0.999
OPP (mmHg) 40.3 ± 5.0 44.3 ± 5.5* 40.9 ± 4.8 40.8 ± 4.9 41.1 ± 5.3 <0.001 <0.001 0.999 0.999 0.871
MBR-V 44.3 ± 5.1 44.3 ± 4.9 45.2 ± 5.2 44.6 ± 5.3 45.1 ± 5.4 0.174 0.999 0.500 0.941 0.730
MBR-V (%) 100.0 ± 0.0 100.4 ± 7.7 102.3 ± 8.4 98.8 ± 7.1 101.3 ± 6.3 0.447 1.000 0.660 1.000 0.949
MBR-T 13.3 ± 2.3 13.4 ± 2.2 13.6 ± 2.2 13.3 ± 2.1 13.5 ± 2.0 0.336 0.994 0.967 0.825 0.999
MBR-T (%) 100.0 ± 0.0 100.4 ± 7.4 102.2 ± 9.6 98.0 ± 7.7 101.7 ± 7.6 0.258 0.990 0.984 0.782 0.987
MBR-A 25.0 ± 3.4 24.8 ± 3.4 25.1 ± 3.4 25.1 ± 3.4 25.3 ± 3.2 0.402 0.924 0.998 0.962 0.981
MBR-A (%) 100.0 ± 0.0 99.2 ± 5.3 101.1 ± 5.6 100.1 ± 3.9 100.8 ± 4.8 0.750 0.984 0.973 0.997 1.000

Values are presented as mean ± standard deviation.

IOP = intraocular pressure; SBP = systolic blood pressure; DBP = diastolic blood pressure; MBP = mean blood pressure; HR = heart rate; bpm = beats per minute; OPP = ocular perfusion pressure; MBR-V = vessel average of the mean blur rate; MBR-T = tissue average of the mean blur rate; MBT-A = overall average of the mean blur rate.

* p < 0.001.

Table 2
Changes in ocular biometric parameters and systemic factors at baseline and at 0, 10, 20, and 30 minutes after the cold pressor test in the male group (n = 18)
Variable Baseline After the cold pressor test p-value


0 min 10 min 20 min 30 min Friedman test Scheffé test

0 min 10 min 20 min 30 min
IOP (mmHg) 13.9 ± 3.3 13.2 ± 3.4 13.1 ± 3.2 13.2 ± 3.2 13.2 ± 3.4 0.111 0.297 0.323 0.378 0.297
SBP (mmHg) 116.5 ± 7.5 121.3 ± 9.3 115.2 ± 9.4 114.7 ± 9.1 115.9 ± 8.2 0.009 0.157 1.000 0.946 0.999
DBP (mmHg) 70.4 ± 4.6 76.5 ± 7.3* 70.2 ± 6.2 69.9 ± 5.3 72.4 ± 5.8 <0.001 0.021 1.000 0.966 0.885
MBP (mmHg) 85.8 ± 5.1 91.4 ± 6.4* 85.2 ± 6.6 84.8 ± 5.5 86.9 ± 5.8 <0.001 0.016 0.996 0.949 0.923
HR (bpm) 82.1 ± 14.5 80.8 ± 13.4 82.8 ± 12.6 80.8 ± 11.9 82.5 ± 14.0 0.605 0.998 0.948 0.981 0.997
OPP (mmHg) 43.2 ± 3.4 47.6 ± 3.9 43.6 ± 3.6 43.3 ± 3.6 44.7 ± 3.3 <0.001 0.002 0.998 1.000 0.730
MBR-V 43.5 ± 4.6 43.7 ± 4.5 45.0 ± 4.8 44.0 ± 5.0 45.0 ± 5.2 0.134 0.997 0.634 0.999 0.750
MBR-V (%) 100.0 ± 0.0 100.6 ± 8.2 103.4 ± 9.4 97.7 ± 6.6 102.4 ± 5.8 0.138 1.000 0.755 0.923 0.908
MBR-T 12.8 ± 2.2 12.8 ± 2.1 13.1 ± 2.2 12.6 ± 2.0 13.0 ± 2.1 0.388 0.982 0.999 0.725 0.999
MBR-T (%) 100.0 ± 0.0 100.5 ± 8.0 102.8 ± 11.8 96.7 ± 8.7 103.2 ± 6.7 0.157 0.991 0.999 0.644 0.950
MBR-A 23.8 ± 2.8 23.8 ± 2.7 24.0 ± 2.7 24.1 ± 2.5 24.3 ± 2.6 0.318 0.999 0.982 0.577 0.697
MBR-A (%) 100.0 ± 0.0 100.3 ± 5.8 100.9 ± 6.8 100.7 ± 4.2 101.0 ± 5.1 0.930 1.000 0.999 0.976 1.000

Values are presented as mean ± standard deviation.

IOP = intraocular pressure; SBP = systolic blood pressure; DBP = diastolic blood pressure; MBP = mean blood pressure; HR = heart rate; bpm = beats per minute; OPP = ocular perfusion pressure; MBR-V = vessel average of the mean blur rate; MBR-T = tissue average of the mean blur rate; MBR-A = overall average of the mean blur rate.

* p < 0.05;

p < 0.01.

Table 3
Changes in ocular biometric parameters and systemic factors at baseline and at 0, 10, 20, and 30 minutes after the cold pressor test in the female group (n = 26)
Variable Baseline After the cold pressor test p-value


0 min 10 min 20 min 30 min Friedmantest Scheffé test

0 min 10 min 20 min 30 min
IOP (mmHg) 12.5 ± 2.1 12.7 ± 2.2 12.3 ± 2.0 12.3 ± 2.1 12.3 ± 2.1 0.399 0.798 0.998 0.998 0.996
SBP (mmHg) 102.2 ± 8.4 108.8 ± 9.3* 103.0 ± 8.6 102.5 ± 9.4 102.8 ± 8.5 <0.001 <0.001 0.995 0.990 1.000
DBP (mmHg) 63.4 ± 7.1 68.8 ± 7.6 64.3 ± 6.0 64.5 ± 7.3 63.5 ± 6.9 0.001 0.039 1.000 1.000 0.999
MBP (mmHg) 76.3 ± 7.0 82.1 ± 7.3 77.2 ± 6.1 77.1 ± 7.2 76.6 ± 6.9 <0.001 0.005 1.000 0.998 1.000
HR (bpm) 82.7 ± 11.1 81.7 ± 11.2 82.8 ± 10.1 82.8 ± 11.1 81.8 ± 10.4 0.575 0.993 0.900 0.983 1.000
OPP (mmHg) 38.3 ± 5.0 42.0 ± 5.3 39.1 ± 4.7 39.1 ± 5.0 38.7 ± 5.1 <0.001 0.005 1.000 0.998 0.999
MBR-V 44.8 ± 5.5 44.7 ± 5.2 45.3 ± 5.5 45.0 ± 5.5 45.2 ± 5.6 0.574 1.000 0.892 0.783 0.974
MBR-V (%) 100.0 ± 0.0 100.2 ± 7.5 101.5 ± 7.7 99.6 ± 7.4 100.5 ± 6.6 0.852 0.999 0.942 0.942 0.999
MBR-T 13.8 ± 2.2 13.8 ± 2.2 14.0 ± 2.2 13.8 ± 2.1 13.8 ± 2.0 0.833 1.000 0.966 0.997 0.999
MBR-T (%) 100.0 ± 0.0 100.3 ± 7.1 101.7 ± 7.9 99.0 ± 6.9 100.7 ± 8.2 0.873 0.999 0.983 0.997 1.000
MBR-A 25.9 ± 3.6 25.5 ± 3.7 25.9 ± 3.7 25.8 ± 3.8 25.9 ± 3.5 0.686 0.760 0.930 0.997 0.997
MBR-A (%) 100.0 ± 0.0 98.5 ± 4.9 101.3 ± 4.6 99.6 ± 3.7 100.6 ± 4.7 0.707 0.967 0.974 1.000 1.000

Values are presented as mean ± standard deviation.

IOP = intraocular pressure; SBP = systolic blood pressure; DBP = diastolic blood pressure; MBP = mean blood pressure; HR = heart rate; bpm = beats per minute; OPP = ocular perfusion pressure; MBR-V = vessel average of the mean blur rate; MBR-T = tissue average of the mean blur rate; MBR-A = overall average of the mean blur rate.

* p < 0.001;

p < 0.05;

p < 0.01.



ABOUT
BROWSE ARTICLES
EDITORIAL POLICY
FOR CONTRIBUTORS
Editorial Office
SKY 1004 Building #701
50-1 Jungnim-ro, Jung-gu, Seoul 04508, Korea
Tel: +82-2-583-6520    Fax: +82-2-583-6521    E-mail: kos@ophthalmology.org                

Copyright © 2024 by Korean Ophthalmological Society.

Developed in M2PI

Close layer
prev next