Visual AcuityNCT04632901
A New Parameter for the Assessment of Distance Visual Capacity: the Critical Visual Acuity (CVA)
An observational study of Visual Acuity, run by Democritus University of Thrace at 1 site in Greece.
Trial summary
The conventional examination of the visual acuity (VA) does not take into account the patient's reading speed. However, the consideration of the speed for the recognition of the VA charts' symbols leads to the more accurate and comprehensive assessment of the visual capacity. Read more about this study
- Who is it for?
- Ages 18 to 75 yearsHealthy volunteers can take part
- Conditions the study is for
- Visual Acuity
- What is being tested?
- VA assessment and CVA assessment
- How many people
- 300 participants
- Where
- 1 siteGreece
- Study dates
- 20 Sep 2020to 20 Dec 2025
- How long will I take part?
- 15 Days
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 75 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: 300 patients who will come to the outpatient clinics of the Ophthalmology Department of the University Hospital of Alexandroupolis, aged 18-75 years, will be examined.
Who may be able to join
- People aged 18 - 75 years
Who cannot join
- neurological diseases
- mental diseases
- mental retardation,
- difficulty reading
- previous intraocular surgery
Trial locations and contacts
1 site in 1 country.
Greece1 site
Department of Ophthalmology, University Hospital of Alexandroupolis
Alexandroupoli, Evros, 68100
About this study
Official title: Development and Validation of a New Parameter for the Assessment of Distance Visual Capacity: the Critical Visual Acuity (CVA)
The conventional examination of the visual acuity (VA) does not take into account the patient's reading speed. However, the consideration of the speed for the recognition of the VA charts' symbols leads to the more accurate and comprehensive assessment of the visual capacity.
Therefore, primary objective of this study is to develop and validate a new parameter for the more comprehensive evaluation of visual capacity: the critical visual acuity (CVA). CVA takes into account the speed of recognition of the symbols of the distance visual charts.
Read the detailed description
In clinical practice, the conventional examination of the VA does not take into account the patient's reading speed, and does not reflect the requirements of everyday life (e.g. driving, watching subtitles on TV), in which each individual has limited time to react. In addition, the VA measured with the conventional method differs significantly among the different examiners, since there is no standard time limit for the patient to read the chart symbols.
However, the consideration of the speed for the recognition of the VA charts' symbols leads to the more accurate and comprehensive assessment of the visual capacity. Therefore, primary objective of this study is to develop and validate a new parameter for the more comprehensive evaluation of visual capacity: the critical visual acuity (CVA), and to determine normal values of population according to age. CVA takes into account the speed of recognition of the symbols of the distance visual charts.
Participants are recruited from the outpatient service of the Department of Ophthalmology of the University Hospital of Alexandroupolis in a consecutive-if-eligible basis. At first, each participant performs the conventional VA test monocularly. Then, he/she performs the CVA test with the same eye. Two different printed Landolt ring charts are used, the first one for VA and the second one for CVA assessment for all participants to avoid memorization. The VA and CVA are evaluated for all participants under the same environmental lighting conditions.
Regarding the VA and CVA examination procedure, the investigator masks the chart lines using a blank piece of paper and reveals one line each time. The investigator instructs the patient to read aloud the 5 letters of the Landolt chart, as quickly and accurately as possible, after hearing the words "Ready!… Go!". At the same time, a second examiner starts a stopwatch to record the reading time (in seconds, to the nearest 0.01 s) when the examiner fully reveals the line and the patient starts to read it. The first examiner counts the number of errors for each line and the second one enters the reading time for each line in a data file. The reading time of each line is compared with the automatically calculated average reading time of the larger lines minus 1.96 (for CVA) or 2.58 (for VA) times the standard deviation (SD) of the reading time of these lines.
Testing stops when the letters are too small for the examinee to discriminate and/or they are read with a speed lower than the maximum reading speed (MRS) of each examinee.
- Conditions
- Visual Acuity
- Being tested
- VA assessment, CVA assessment
- Keywords
- maximum reading speed, critical visual acuity, visual capacity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
VA assessmentDiagnostic test
The VA of all participants will be evaluated by counting the smallest line that can be read within a time duration greater than or equal to the average reading time of the larger lines minus 2.58 times the SD of the reading time of these lines.
In clinical practice, the VA is the common parameter of VA adding a tolerant time limit to clearly determine the end of the test.
CVA assessmentDiagnostic test
The CVA of all participants will be evaluated by counting the smallest line that can be read within a time duration greater than or equal to the average reading time of the larger lines minus 1.96 times the SD of the reading time of these lines.
In clinical practice, the CVA is the minimum VA that can be read in maximal speed.
| Study group | Role | What they receive |
|---|---|---|
| Testing of Visual Acuity (VA) Group | The same participants will undergo VA and CVA test with two different Landolt C charts under the same lighting conditions. Receives: Diagnostic Test: VA assessment | |
| Testing of Critical Visual Acuity (CVA) Group | The same participants will undergo VA and CVA test with two different Landolt C charts under the same lighting conditions. Receives: Diagnostic Test: CVA assessment |
What is being measured
The primary outcome is the main question the study is designed to answer.
Critical Visual Acuity (CVA)
The smallest line (measured in letters) that can be read with the maximum reading speed, i.e., with speed greater than or equal to the average reading speed of the larger lines minus 1.96 times the standard deviation (SD) of the reading speed of these lines. In clinical practice, the CVA is the minimum VA that can be read in maximal speed.
Measured: 6 months
Visual Acuity (VA)
The smallest line (measured in letters) that can be read with speed greater than or equal to the average reading speed of the larger lines minus 2.58 times the standard deviation (SD) of the reading speed of these lines. In clinical practice, the VA is the common parameter of VA adding a tolerant time limit to clearly determine the end of the test.
Measured: 6 months
Secondary outcomes (1)
Intraclass Correlation Coefficients (ICCs) for study participants
Level of agreement between CVA and VA are evaluated by calculation of the ICCs for these 2 parameters.
Measured: through study completion, an average of 3 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Nov 2020
- Study start20 Sep 2020
- Primary completion20 Jul 2025 (estimated)
- Study completion20 Dec 2025 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Visual AcuityStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 300 participants (estimated)
- Target duration
- 15 Days
Sponsor and investigators
- Lead sponsor
- Democritus University of Thrace
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Georgios Labiris, Democritus University of Thrace
- Investigators
- Georgios Labiris, MD, PhD, Study chair, Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis, Greece
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04632901
- Sponsor's protocol ID
- ES12/Th3/17-9-2020
- Status last verified
- Jun 2025
- First submitted
- 12 Nov 2020
- Last updated
- 11 Jul 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 11 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Development and Validation of a New Parameter for the Assessment of Distance Visual Capacity: the Critical Visual Acuity (CVA)
- ClinicalTrials.gov ID
- NCT04632901
- Acronym / sponsor ID
- ES12/Th3/17-9-2020
- Conditions
- Visual Acuity
- Keywords
- maximum reading speed, critical visual acuity, visual capacity
- Study type
- Observational
- Recruitment status
- Active, not recruiting
- Enrolment
- 300 participants (estimated)
- Lead sponsor
- Democritus University of ThraceUniversity, hospital or other
- Study start
- 20 Sep 2020 (actual)
- Primary completion
- 20 Jul 2025 (estimated)
- Study completion
- 20 Dec 2025 (estimated)
- First posted
- 17 Nov 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The conventional examination of the visual acuity (VA) does not take into account the patient's reading speed. However, the consideration of the speed for the recognition of the VA charts' symbols leads to the more accurate and comprehensive assessment of the visual capacity.
Therefore, primary objective of this study is to develop and validate a new parameter for the more comprehensive evaluation of visual capacity: the critical visual acuity (CVA). CVA takes into account the speed of recognition of the symbols of the distance visual charts.
Detailed description
In clinical practice, the conventional examination of the VA does not take into account the patient's reading speed, and does not reflect the requirements of everyday life (e.g. driving, watching subtitles on TV), in which each individual has limited time to react. In addition, the VA measured with the conventional method differs significantly among the different examiners, since there is no standard time limit for the patient to read the chart symbols.
However, the consideration of the speed for the recognition of the VA charts' symbols leads to the more accurate and comprehensive assessment of the visual capacity. Therefore, primary objective of this study is to develop and validate a new parameter for the more comprehensive evaluation of visual capacity: the critical visual acuity (CVA), and to determine normal values of population according to age. CVA takes into account the speed of recognition of the symbols of the distance visual charts.
Participants are recruited from the outpatient service of the Department of Ophthalmology of the University Hospital of Alexandroupolis in a consecutive-if-eligible basis. At first, each participant performs the conventional VA test monocularly. Then, he/she performs the CVA test with the same eye. Two different printed Landolt ring charts are used, the first one for VA and the second one for CVA assessment for all participants to avoid memorization. The VA and CVA are evaluated for all participants under the same environmental lighting conditions.
Regarding the VA and CVA examination procedure, the investigator masks the chart lines using a blank piece of paper and reveals one line each time. The investigator instructs the patient to read aloud the 5 letters of the Landolt chart, as quickly and accurately as possible, after hearing the words "Ready!… Go!". At the same time, a second examiner starts a stopwatch to record the reading time (in seconds, to the nearest 0.01 s) when the examiner fully reveals the line and the patient starts to read it. The first examiner counts the number of errors for each line and the second one enters the reading time for each line in a data file. The reading time of each line is compared with the automatically calculated average reading time of the larger lines minus 1.96 (for CVA) or 2.58 (for VA) times the standard deviation (SD) of the reading time of these lines.
Testing stops when the letters are too small for the examinee to discriminate and/or they are read with a speed lower than the maximum reading speed (MRS) of each examinee.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Target follow-up
- 15 Days
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Testing of Visual Acuity (VA) Group | – | Diagnostic Test: VA assessmentThe same participants will undergo VA and CVA test with two different Landolt C charts under the same lighting conditions. |
| Testing of Critical Visual Acuity (CVA) Group | – | Diagnostic Test: CVA assessmentThe same participants will undergo VA and CVA test with two different Landolt C charts under the same lighting conditions. |
Who may qualify
- Ages
- 18 to 75 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- 300 patients who will come to the outpatient clinics of the Ophthalmology Department of the University Hospital of Alexandroupolis, aged 18-75 years, will be examined.
Key inclusion criteria (1 listed)
- People aged 18 - 75 years
Key exclusion criteria (5 listed)
- neurological diseases
- mental diseases
- mental retardation,
- difficulty reading
- previous intraocular surgery
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| VA assessmentThe VA of all participants will be evaluated by counting the smallest line that can be read within a time duration greater than or equal to the average reading time of the larger lines minus 2.58 times the SD of the reading time of these lines. In clinical practice, the VA is the common parameter of VA adding a tolerant time limit to clearly determine the end of the test. | Diagnostic test | Testing of Visual Acuity (VA) Group |
| CVA assessmentThe CVA of all participants will be evaluated by counting the smallest line that can be read within a time duration greater than or equal to the average reading time of the larger lines minus 1.96 times the SD of the reading time of these lines. In clinical practice, the CVA is the minimum VA that can be read in maximal speed. | Diagnostic test | Testing of Critical Visual Acuity (CVA) Group |
Primary outcome
Critical Visual Acuity (CVA)
Time frame: 6 months
The smallest line (measured in letters) that can be read with the maximum reading speed, i.e., with speed greater than or equal to the average reading speed of the larger lines minus 1.96 times the standard deviation (SD) of the reading speed of these lines. In clinical practice, the CVA is the minimum VA that can be read in maximal speed.
Visual Acuity (VA)
Time frame: 6 months
The smallest line (measured in letters) that can be read with speed greater than or equal to the average reading speed of the larger lines minus 2.58 times the standard deviation (SD) of the reading speed of these lines. In clinical practice, the VA is the common parameter of VA adding a tolerant time limit to clearly determine the end of the test.
1 secondary outcome
Intraclass Correlation Coefficients (ICCs) for study participants
Time frame: through study completion, an average of 3 months
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Jul 2025.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Georgios Labiris, MD, PhD study chair
Department of Ophthalmology, University Hospital of Alexandroupolis, Alexandroupolis, Greece
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Visual Acuity, run by Democritus University of Thrace at 1 site in Greece.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 11 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Greece. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Critical Visual Acuity (CVA) (time frame: 6 months). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Jul 2025.