Hydration Status and Ocular Parameters Study

NCT07177131 | Not Yet Recruiting

• 1 other identifier: JC092025
• Study Type: interventional
• Target: 60
• Locations: 0 countries
• Sites: N/A

Brief Summary

This study will examine how hydration status (drinking a large amount of water or avoiding water for a short period of time) affects the eye. Healthy adult volunteers will participate in two sessions: one after mild dehydration (no water for 12 hours) and one after drinking 2 liters of water within 4 hours. At each session, detailed eye measurements will be taken, including scans of the retina and optic nerve using optical coherence tomography (OCT), corneal imaging with Pentacam, and eye length measurements with an optical biometer. The results from the two conditions will be compared within the same participants. The main goal is to determine whether hydration influences the thickness of the retina (macula). Secondary goals include assessing changes in the optic nerve, cornea, and other biometric eye parameters. The study involves only non-invasive tests and minimal risk. Findings may help improve understanding of how hydration affects the eye and may be important for clinical practice, such as planning cataract or refractive surgery.

Conditions

Hydration Status; Macular Thickness; Ocular Biometry

Outcome Measures

Primary Outcomes (1)

• Change in macular thickness between dehydration and hyperhydration states

  Macular thickness (central subfield, parafoveal, and perifoveal regions) will be measured using Zeiss Cirrus HD-OCT. Each participant will undergo measurements in both hydration states, and paired comparisons will be performed.

  Within 1 week (cross-over design with ≥7-day washout period)

Study Arms (2)

Relative Dehydration

EXPERIMENTAL

12-hour fluid restriction (≤250 ml fluids until 20h previous day)

Behavioral: Relative Dehydration Protocol

Hyperhydration

EXPERIMENTAL

2 liters of water within 4 hours before testing

Behavioral: Hyperhydration Protocol

Interventions

Relative Dehydration Protocol BEHAVIORAL

Participants will abstain from water intake for 12 hours prior to the study visit. Food is allowed, but fluid intake is limited to a maximum of 250 ml until 20:00 h on the previous evening. Eye measurements will be performed in the morning (8-10 h).

Relative Dehydration

Hyperhydration Protocol BEHAVIORAL

Participants will consume 2 liters of water within 4 hours prior to the study visit. Eye measurements will be performed in the morning (8-10 h).

Hyperhydration

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Healthy adult volunteers aged 18 to 65 years
• Normal ophthalmological findings
• Best corrected visual acuity (BCVA) ≥ 1.0 (decimal)
• Willingness to participate and provide written informed consent

You may not qualify if:

• Known ocular diseases (e.g., glaucoma, keratoconus, retinal pathology)
• History of ocular surgery
• Systemic diseases affecting hydration status (e.g., diabetes mellitus, kidney disease)
• Any condition that, in the investigator's opinion, could interfere with study participation or data quality
• Refusal to participate

Sponsors & Collaborators

• Ante Kreso: lead
• University Hospital of Split: collaborator
• University of Split, School of Medicine: collaborator

Central Study Contacts

Ante Krešo, MD

CONTACT

+385 21 556 402; ante.kreso@mefst.hr

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: September 9, 2025
• First Posted: September 16, 2025
• Study Start: September 25, 2025
• Primary Completion: November 1, 2025
• Study Completion: December 1, 2025
• Last Updated: September 22, 2025

Record last verified: 2025-09