Hydration Status and Ocular Parameters Study

Prospective, Randomized Cross-over Within-subject Study on the Effects of Dehydration and Hyperhydration on Macular Thickness, Corneal Morphology, and Ocular Biometric Parameters Measured by OCT, Pentacam and Optical Biometer

Status

Not yet recruiting

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT07177131

Acronym

HYDRI-EYE

Enrollment

Registered

2025-09-16

Start date

2025-09-25

Completion date

2025-12-01

Last updated

2025-09-22

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Hydration Status, Macular Thickness, Ocular Biometry

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.

Interventions

BEHAVIORALRelative Dehydration Protocol

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).

BEHAVIORALHyperhydration Protocol

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).

Study design

Allocation

RANDOMIZED

Intervention model

CROSSOVER

Primary purpose

BASIC_SCIENCE

Masking

SINGLE (Outcomes Assessor)

Eligibility

Sex/Gender

ALL

Age

18 Years to 65 Years

Healthy volunteers

Yes

Inclusion criteria

* 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

Exclusion criteria

* 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

Design outcomes

Primary

Measure	Time frame	Description
Change in macular thickness between dehydration and hyperhydration states	Within 1 week (cross-over design with ≥7-day washout period)	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.

Contacts

Primary ContactAnte Krešo, MD

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

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026