An observational study in Visual Acuity, Refractive Errors and Myopia, sponsored by Trakya University. Not yet recruiting. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-12-04.
Sponsored by Trakya University · Observational
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.
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.
420 studies on the registry are indexed under Refractive Errors; 59 are open to participants now.
This study's planned enrollment of 200 is above the median of 150 across 108 observational studies indexed under Refractive Errors.
Browse Refractive Errors studies →Trakya University is the lead sponsor of 155 studies on the registry; 15 are open to participants now.
Counted across the registry records on this site, refreshed daily.
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).
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Turkish-speaking individuals able to understand the study purpose
Willingness to participate and provide written
Participants with or without refractive errors (e.g., myopia, hyperopia, astigmatism)
Exclusion Criteria:
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
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
Agreement between DDIVAT (Turkish version) and Snellen chart visual acuity measurements
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.
Time frame: During a single study visit (same day assessment)
No study locations are listed for this record.
Plan to share: No — 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.
Start is estimated for Dec 2025; primary completion for Apr 2026, 4 months later.
Of 35 non-industry observational studies under Refractive Errors, half reached primary completion within 26 months of starting (the median), counting those still running; a quarter within 8 and three quarters within 47. This study's planned 4 months is below that.
Counting every sponsor, half of 42 studies reached it within 19 months; a quarter within 8 and three quarters within 47.
How these figures are worked out, and which studies are left out of them.
This study is not yet recruiting, as verified in Oct 2025. You cannot join it, but the record below documents what was studied.
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