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Enrolling by invitationNCT07208838Updated Oct 6, 2025

Validation of DDIVAT Digital Optotypes for Distance Visual Acuity Testing Among the Bulgarian Population

An observational study in Vision Screening, sponsored by Plovdiv Medical University. Enrolling by invitation at 1 site in Bulgaria. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-10-06.

Sponsored by Plovdiv Medical University · Observational

From the registry’s dates

  • Primary completion was expected by Jul 2026, 4 months ago, but the record still lists the study as enrolling by invitation.
Study type
Observational
Model
Cohort
Time perspective
Prospective
Enrollment
150
Ages
18 Years and older
Sex
All
01

Study summary

To compare distance visual acuity in Bulgarian patients over 18 years of age using two different methods - the Snellen method and the DIDIVAT digital online optotypes. For the purpose of this study, it is planned to examine native visual acuity (with and without prescribed optical correction), without additional mydriasis in both ways, of 150 Bulgarian patients (75 women and 75 men) over 18 years of age, hospitalized in a university eye clinic at St. George University Hospital and healthy volunteers willing to participate in the study. The statistical analysis that will be performed will aim to compare whether the two methods for determining distance visual acuity are identical in results, as well as to validate the application for the Bulgarian population.The study is expected to prove that the distance visual acuity of patients examined by both methods is identical.

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Conditions studied

  • Vision Screening
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In context

Lead sponsor

Plovdiv Medical University is the lead sponsor of 16 studies on the registry; 5 are open to participants now.

Counted across the registry records on this site, refreshed daily.

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Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
Yes
Sampling method
Non-probability sample

Study population

Bulgarian speaking patients (75 women and 75 men) over 18 years of age, hospitalized in a university eye clinic at St. George University Hospital and healthy volunteers willing to participate in the study.

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.

Inclusion criteria

  • Bulgarian speaking patients (75 women and 75 men) over 18 years of age, hospitalized in a university eye clinic at St. George University Hospital and healthy volunteers willing to participate in the study.

Exclusion criteria

Exclusion Criteria:

  • Patients of less than 18 years of age.
05

Study design

Observational model
Cohort
Time perspective
Prospective
Enrollment
150 participants (estimated)
Target follow-up
1 Day
Patient registry
Yes

Groups and cohorts

  • Healthy participants

    75 males and 75 females over 18 years of age

    Diagnostic Test: To test visual acuity in 150 Bulgarian patients over 18 years of age using Snellens visual acuity chart and DDIVAT optotypes

Interventions

  • Diagnostic testTo test visual acuity in 150 Bulgarian patients over 18 years of age using Snellens visual acuity chart and DDIVAT optotypes

    The study compares newly developed visual acuity test (DDIVAT) with standart method for visual acuity testing used worldwide

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What researchers measure

Primary outcomes

  1. The study is expected to prove that the distance visual acuity of patients examined by both methods is identical.

    Time frame: 12 monts

07

Study locations

1 site
  • Medical University Plovdiv
    Plovdiv, 4004, Bulgaria
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References and documents

Publications

  • Bakirtzis M, Michaleakou E, Martidou ME, Lahana E, Kostagiolas P, Niakas D, Labiris G. Visual Acuity Screening of Refugees and Immigrants with a Web-Based Digital Test: A Pilot Study. Acta Medica (Hradec Kralove). 2024;67(3):79-86. doi: 10.14712/18059694.2025.2. PubMed 39963735 ↗
  • Labiris G, Panagiotopoulou EK, Duzha E, Tzinava M, Perente A, Konstantinidis A, Delibasis K. Development and Validation of a Web-Based Reading Test for Normal and Low Vision Patients. Clin Ophthalmol. 2021 Sep 22;15:3915-3929. doi: 10.2147/OPTH.S314943. eCollection 2021. PubMed 34588763 ↗
  • Labiris G, Panagiotopoulou EK, Chatzimichael E, Tzinava M, Mataftsi A, Delibasis K. Introduction of a digital near-vision reading test for normal and low vision adults: development and validation. Eye Vis (Lond). 2020 Oct 22;7:51. doi: 10.1186/s40662-020-00216-0. eCollection 2020. PubMed 33102611 ↗
  • Labiris G, Panagiotopoulou EK, Delibasis K, Duzha E, Bakirtzis M, Panagis C, Boboridis K, Mokka A, Balidis M, Damtsi C, Ntonti P. Validation of a web-based distance visual acuity test. J Cataract Refract Surg. 2023 Jul 1;49(7):666-671. doi: 10.1097/j.jcrs.0000000000001176. PubMed 36853857 ↗

Individual participant data

Plan to share: Yes

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Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Start is estimated for Oct 2025; primary completion for Jul 2026, 9 months later.

How these figures are worked out, and which studies are left out of them.

Registered
Sep 28, 2025
First posted
Oct 6, 2025
StartEst.
Oct 1, 2025
Primary completionEst.
Jul 1, 2026
CompletionEst.
Jul 1, 2026
Last update
Oct 6, 2025
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Oct 6, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
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Registry details

Key details

Study ID
NCT07208838
Lead sponsor
Plovdiv Medical University
Collaborators
Democritus University of Thrace
Responsible party
Vasil Marinov (MD, PhD, Plovdiv Medical University) — Principal investigator
First posted
Oct 6, 2025
Start date
Oct 1, 2025 (estimated)
Primary completion
Jul 1, 2026 (estimated)
Completion
Jul 1, 2026 (estimated)
Last update
Oct 6, 2025

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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No contact was published for this record. The registry link below has the sponsor’s details.

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