Assessing the Turkish DDIVAT for Visual Acuity Measurement

November 26, 2025 updated by: Prof. Dr. Hande Guclu, Trakya University

Validation of the Turkish Version of the DDIVAT Visual Acuity Measuring Device in a Turkish-speaking Population

The goal of this observational methodological study is to validate the Turkish version of the DDIVAT visual acuity measuring device in a Turkish-speaking adult population.

The main questions it aims to answer are:

Does the Turkish version of the DDIVAT provide reliable and valid visual acuity measurements in Turkish speakers?

Are the results of the DDIVAT comparable to those obtained with the standard Snellen chart used in clinical practice?

Researchers will compare DDIVAT visual acuity test results with Snellen chart results to see if both methods produce consistent measurements.

Participants will:

Be adults aged 18 years or older, including both patients and healthy volunteers.

Undergo visual acuity testing using the DDIVAT system displayed on a smart TV connected to the university server.

Have their visual acuity re-measured using the standard Snellen optotype under the same conditions.

No medication or invasive procedure will be used. The study carries no risk to participants.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This study is a non-interventional, observational methodological validation study designed to evaluate the validity and reliability of the Turkish version of the DDIVAT (Digital Distance Interactive Visual Acuity Test) in a Turkish-speaking population.

The DDIVAT visual acuity test was originally developed and validated at Democritus University of Thrace (Greece) and has been approved by the National Medicines Organization as a Class I medical device. The current study aims to determine whether the Turkish-translated version of this visual acuity measurement tool performs consistently and accurately among Turkish-speaking participants.

Visual acuity is one of the most fundamental components of a comprehensive ophthalmological examination. It measures the clarity or sharpness of vision, which can be influenced by refractive errors and a variety of ocular diseases. Accurate and accessible tools for measuring visual acuity are therefore essential in both clinical and research settings.

In this study, 200 adult participants (aged 18 years and older) will be recruited from Trakya University Hospital, Department of Ophthalmology (Edirne, Türkiye). The study population will include both healthy volunteers and patients presenting to the ophthalmology clinic.

Each participant will undergo two visual acuity measurements under standardized conditions:

DDIVAT visual acuity test (Turkish version), administered via a smart TV connected to the university's secure server.

Snellen chart test, which represents the standard clinical practice currently used at Trakya University Hospital.

Measurements will be taken monocularly (each eye tested separately) while participants wear their current optical correction (e.g., eyeglasses or contact lenses).

The study will compare the two measurement methods to determine:

The level of agreement between DDIVAT and Snellen test results.

The test-retest reliability of the Turkish DDIVAT.

Since no medication, invasive procedure, or experimental intervention will be applied, the study poses no potential risk to participants. All procedures will comply with the Declaration of Helsinki, Good Clinical Practice (GCP) principles, and relevant data protection regulations.

Collected data will be stored anonymously and used solely for research purposes. The findings are expected to provide evidence supporting the use of DDIVAT as a reliable digital visual acuity tool for Turkish-speaking populations, enhancing accessibility and standardization of visual testing in both clinical and teleophthalmology contexts.

Study Type

Observational

Enrollment (Estimated)

200

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Turkish-speaking adults (aged 18 and older), including both healthy volunteers and ophthalmology clinic patients, will be recruited from Trakya University Hospital, Department of Ophthalmology (Edirne, Türkiye).

Description

Inclusion Criteria:

  • Adults aged 18 years or older

Turkish-speaking individuals able to understand the study purpose

Willingness to participate and provide written informed consent

Participants with or without refractive errors (e.g., myopia, hyperopia, astigmatism)

Exclusion Criteria:

  • Age below 18 years

Individuals unable to complete visual acuity testing

Presence of severe ocular pathology (e.g., corneal opacity, retinal detachment) that prevents accurate measurement

Cognitive or communication difficulties preventing informed consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Participants Undergoing Visual Acuity Testing
All enrolled participants (n = 200) will complete two visual acuity measurements during a single visit: one using the DDIVAT (Digital Device Independent Visual Acuity Test) Turkish version and one using the standard Snellen chart. The study compares the agreement and test-retest reliability of these two methods. No intervention, medication, or treatment is applied.
Diagnostic test: DDIVAT Visual Acuity Test (Turkish Version)
Participants' visual acuity will be measured using the Turkish version of the DDIVAT digital visual acuity device and compared with Snellen chart results. No treatment or invasive procedure will be performed.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Agreement between DDIVAT (Turkish version) and Snellen chart visual acuity measurements
Time Frame: During a single study visit (same day assessment)
The primary outcome is to assess the level of agreement between visual acuity scores obtained using the Turkish version of the DDIVAT digital visual acuity device and those obtained using the standard Snellen chart. Statistical analysis will include correlation and Bland-Altman agreement methods to evaluate consistency and validity between the two testing methods.
During a single study visit (same day assessment)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Trakya University

Investigators

  • Principal Investigator: Hande Güçlü, M.D., Prof. Dr., Trakya University Faculty of Medicine Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

December 1, 2025

Primary Completion (Estimated)

April 30, 2026

Study Completion (Estimated)

May 31, 2026

Study Registration Dates

First Submitted

November 16, 2025

First Submitted That Met QC Criteria

November 16, 2025

First Posted (Estimated)

November 21, 2025

Study Record Updates

Last Update Posted (Estimated)

December 4, 2025

Last Update Submitted That Met QC Criteria

November 26, 2025

Last Verified

October 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Turkish DDIVAT TrakyaUni

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

This is a minimal-risk, non-interventional validation study conducted at a single institution. The collected data will be anonymized and analyzed internally. Individual participant-level data will not be shared outside Trakya University Faculty of Medicine due to institutional data-protection policies.

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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