UMIN-ICDS Clinical Trial
| Unique ID issued by UMIN | UMIN000063588 |
|---|---|
| Receipt number | R000072764 |
| Scientific Title | A Prospective Crossover Study of Acute Changes in Intraocular Pressure and Retinal Blood Flow Indices Following Sauna Exposure in Healthy Adults |
| Date of disclosure of the study information | 2026/11/10 |
| Last modified on | 2026/11/10 22:32:59 |
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Basic information
Public title
Changes in Eye Pressure and Retinal Blood Flow Indices Following Sauna Bathing in Healthy Adults
Acronym
TOTONOU Study
Scientific Title
A Prospective Crossover Study of Acute Changes in Intraocular Pressure and Retinal Blood Flow Indices Following Sauna Exposure in Healthy Adults
Scientific Title:Acronym
TOTONOU Study
Region
| Japan |
Condition
Condition
Healthy Adult
Classification by specialty
| Ophthalmology |
Classification by malignancy
Others
Genomic information
NO
Objectives
Narrative objectives1
To investigate acute changes in intraocular pressure and superficial capillary plexus (SCP) vessel density following sauna exposure in healthy adults compared with a resting control condition.
Basic objectives2
Others
Basic objectives -Others
To investigate the physiological effects of sauna bathing on intraocular pressure, ocular circulation, and systemic hemodynamics in healthy adults.
Trial characteristics_1
Exploratory
Trial characteristics_2
Explanatory
Developmental phase
Not applicable
Assessment
Primary outcomes
Changes in intraocular pressure (IOP) associated with sauna bathing and rest interventions. IOP will be measured using a rebound tonometer (iCare) before and after each intervention to evaluate changes according to intervention condition and measurement time point.
Key secondary outcomes
Changes in ocular circulation parameters assessed by optical coherence tomography angiography (OCTA), blood pressure, heart rate, and mean ocular perfusion pressure (MOPP). Changes before and after the interventions will be evaluated to assess the effects of sauna bathing and rest.
Base
Study type
Interventional
Study design
Basic design
Cross-over
Randomization
Non-randomized
Randomization unit
Blinding
Open -no one is blinded
Control
No treatment
Stratification
NO
Dynamic allocation
NO
Institution consideration
Institution is not considered as adjustment factor.
Blocking
NO
Concealment
No need to know
Intervention
No. of arms
2
Purpose of intervention
Diagnosis
Type of intervention
| Behavior,custom |
Interventions/Control_1
Group AB (sauna-first sequence): Participants undergo the sauna intervention in the first period, followed by the resting control condition in the second period, with a 7-day interval between periods.
Under the sauna condition, baseline blood pressure, intraocular pressure (IOP), and optical coherence tomography angiography (OCTA) are assessed at Shizuoka Red Cross Hospital (T0). Participants then undergo two cycles consisting of 10 minutes of sauna bathing, 1 minute of cold-water immersion, and 10 minutes of recovery in ambient air. Blood pressure and IOP are measured after each sauna exposure (S1, S2), cold-water immersion (W1, W2), and recovery period (A1, A2). After returning to the hospital, blood pressure, IOP, and OCTA are reassessed.
Under the resting control condition, participants remain seated at rest in the hospital. Blood pressure, IOP, and OCTA are measured at baseline (T0). Blood pressure and IOP are subsequently measured at time points corresponding to S1, W1, A1, S2, W2, and A2 of the sauna condition. OCTA is repeated 3 hours after T0.
Interventions/Control_2
Group BA (rest-first sequence): Participants undergo the resting control condition in the first period, followed by the sauna intervention in the second period, with a 7-day interval between periods.
Under the resting control condition, baseline blood pressure, intraocular pressure (IOP), and optical coherence tomography angiography (OCTA) are assessed at Shizuoka Red Cross Hospital (T0). Participants remain seated at rest in the hospital. Blood pressure and IOP are measured at time points corresponding to S1, W1, A1, S2, W2, and A2 of the sauna condition. OCTA is repeated 3 hours after T0.
Under the sauna condition, baseline blood pressure, IOP, and OCTA are measured before the intervention (T0). Participants then undergo two cycles consisting of 10 minutes of sauna bathing, 1 minute of cold-water immersion, and 10 minutes of recovery in ambient air. Blood pressure and IOP are measured after each sauna exposure (S1, S2), cold-water immersion (W1, W2), and recovery period (A1, A2). After returning to the hospital, blood pressure, IOP, and OCTA are reassessed.
Interventions/Control_3
Interventions/Control_4
Interventions/Control_5
Interventions/Control_6
Interventions/Control_7
Interventions/Control_8
Interventions/Control_9
Interventions/Control_10
Eligibility
Age-lower limit
| 20 | years-old | <= |
Age-upper limit
| 55 | years-old | >= |
Gender
Male and Female
Key inclusion criteria
Participants must meet all of the following criteria:
1. Healthy adults aged 20-55 years.
2. Employees of Shizuoka Red Cross Hospital.
3. Individuals who have provided written informed consent to participate in the study.
4. Individuals with experience of sauna bathing within the past year and no history of severe discomfort, syncope, chest pain, or similar adverse symptoms during sauna use.
Key exclusion criteria
Participants meeting any of the following criteria will be excluded:
1. History of cardiac disease.
2. History of hypertension or current use of antihypertensive medications.
3. History of glaucoma or other ocular diseases.
4. Pregnancy or possible pregnancy.
5. History of severe discomfort, presyncope, syncope, chest pain, or similar adverse symptoms during previous sauna use.
6. Individuals deemed unsuitable for participation by the principal investigator for safety reasons.
Target sample size
40
Research contact person
Name of lead principal investigator
| 1st name | Takahiro |
| Middle name | |
| Last name | Matsuoka |
Organization
Shizuoka Red Cross Hospital
Division name
Department of Ophthalmology
Zip code
420-0853
Address
8-2 Otemachi, Aoi-ku, Shizuoka, Shizuoka 420-0853, Japan
TEL
054-254-4311
oph.matsuoka.0902@gmail.com
Public contact
Name of contact person
| 1st name | Takahiro |
| Middle name | |
| Last name | Matsuoka |
Organization
Shizuoka Red Cross Hospital
Division name
Department of Ophthalmology
Zip code
420-0853
Address
8-2 Otemachi, Aoi-ku, Shizuoka, Shizuoka 420-0853, Japan
TEL
054-254-4311
Homepage URL
oph.matsuoka.0902@gmail.com
Sponsor or person
Institute
Shizuoka Red Cross Hospital
Institute
Department
Personal name
Funding Source
Organization
Shizuoka Red Cross Hospital
Organization
Division
Category of Funding Organization
Other
Nationality of Funding Organization
Other related organizations
Co-sponsor
Name of secondary funder(s)
IRB Contact (For public release)
Organization
Shizuoka Red Cross Hospital
Address
8-2 Otemachi, Aoi-ku, Shizuoka, 420-0853, Japan
Tel
054-254-4311
oph.matsuoka.0902@gmail.com
Secondary IDs
Secondary IDs
NO
Study ID_1
Org. issuing International ID_1
Study ID_2
Org. issuing International ID_2
IND to MHLW
Institutions
Institutions
Other administrative information
Date of disclosure of the study information
| 2026 | Year | 11 | Month | 10 | Day |
Related information
URL releasing protocol
Publication of results
Unpublished
Result
URL related to results and publications
Number of participants that the trial has enrolled
40
Results
IOP and MOPP trajectories differed between conditions (both p<0.001). IOP differences (sauna minus rest) were -4.09/-4.78 mmHg after sauna and -3.12/-3.32 mmHg after cold immersion (all adjusted p<0.001), but not significant after recovery. MOPP differed by -4.82 mmHg after the second cold immersion (adjusted p=0.020). VD and PD differed by -0.80 mm-1 and -3.64 percentage points (adjusted p=0.007), but not after baseline adjustment. FAZ area showed no significant difference.
Results date posted
| 2026 | Year | 11 | Month | 10 | Day |
Results Delayed
Results Delay Reason
Date of the first journal publication of results
Baseline Characteristics
Participant flow
Adverse events
No adverse events were observed during the study period.
Outcome measures
Primary outcome:
Changes in intraocular pressure (IOP) over time under sauna and rest conditions. IOP is measured using an iCare tonometer at baseline (T0), immediately after the intervention (T1 or T1'), at the post-intervention assessment (T2), and 30 minutes after T2 (T3).
Secondary outcomes:
1. Change in overall vessel density of the superficial capillary plexus (SCP) measured by OCTA (NIDEK Mirante, 3x3 mm) from T0 to T2.
2. Change in foveal avascular zone (FAZ) area.
3. Changes in blood pressure and heart rate at T0, T1 or T1', and T2.
Plan to share IPD
IPD sharing Plan description
Progress
Recruitment status
Completed
Date of protocol fixation
| 2026 | Year | 04 | Month | 01 | Day |
Date of IRB
| 2026 | Year | 05 | Month | 31 | Day |
Anticipated trial start date
| 2026 | Year | 06 | Month | 01 | Day |
Last follow-up date
| 2026 | Year | 10 | Month | 18 | Day |
Date of closure to data entry
Date trial data considered complete
Date analysis concluded
Other
Other related information
Management information
Registered date
| 2026 | Year | 11 | Month | 10 | Day |
Last modified on
| 2026 | Year | 11 | Month | 10 | Day |
Link to view the page
Value
https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000072764
