Clinical Investigation of the Vision-R800 Device.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Investigation of the Vision-R800 Device. (NCT04208750), a randomized phase 4 study. The primary outcome is Subjective Questionnaire Response.

2. Clinical Question

In practical statistical terms, the question concerns how participants rated or preferred the refraction experiences, not a clinical outcome such as a change in vision. Because the study is described as crossover, the intended comparison appears to involve experience under both refraction conditions. That design can make within-participant comparisons possible, but the registry record does not give enough detail to establish the exact analysis or how responses were linked across conditions.

The record identifies four preference dimensions but does not specify the response options, their ordering, or whether each question asked which condition was preferred or asked for a rating of each condition. It also does not report how missing answers were handled. Accordingly, the stated clinical question can be described, but the direction and size of any preference cannot be determined from the registry record.

3. Trial Design

The registry record describes a randomized, bilateral, crossover dispensing study of a standard and VR800 refraction and associated spectacle lenses. The two listed device interventions are the Vision R-800 Phoropter and the Standard Phoropter, corresponding to R-Refraction and S-Refraction. The record lists myopia, hyperopia, astigmatism, and presbyopia as conditions. Registry enrollment is 119, and the study status is completed.

In a crossover design, participants receive or experience more than one study condition, so comparisons may be made within participants rather than only between separate groups. This is general design context; the registry does not report the treatment sequence, the interval between conditions, a washout period, or whether those features were used. The arm descriptions are empty, so they do not add detail about what participants did in each condition. The record also does not explain how bilateral dispensing was conducted or whether both eyes were assessed in the same way.

Allocation is listed as randomized and masking as none. The record does not say what was randomized, how the randomization sequence was generated, or whether allocation was concealed. It identifies the study as PHASE4, while the official title includes “Phase 2”; the registry record does not explain this difference.

The listed start date is 2019-11-18, and the primary completion date is 2021-02-01. The stated timeframe for the primary questionnaire is at Visit 5 (final visit), up to 5 weeks. The record does not describe recruitment flow, completion by condition, protocol deviations, or the number of participants contributing questionnaire responses. These omissions limit how fully the conduct and analysis of the crossover comparison can be reconstructed.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Subjective Questionnaire Response, measured over at Visit 5 (final visit), up to 5 weeks.

The primary outcome is titled “Subjective Questionnaire Response” and is measured in participants. Its description says that patient questions addressed preference for refraction in terms of quickness, efficiency, comfort, and stress. The assessment is scheduled at Visit 5 (final visit), up to 5 weeks.

Questionnaires are used when the outcome of interest is a participant’s experience or preference, which cannot be represented by an instrument reading alone. For a device comparison involving refraction, perceived convenience and comfort may be relevant aspects of the service experience. This is a general rationale for patient-reported outcomes; the registry record does not state why these particular questions were selected or how they were validated.

The record does not give the response scale, the exact wording of the questions, how each response category was coded, or whether a participant could report no preference. It also does not state whether the four dimensions were analyzed separately or combined into a single endpoint. The posted record indicates that the primary outcome has several categories or time points and is not reduced to one comparison. Category-specific results are not reported in the registry record. As a result, the endpoint’s intended topic is clear, but its operational definition and observed response distribution are not available for interpretation.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends on knowing how an outcome was defined, which participants contributed data, how observations were compared, and how uncertainty was quantified. The registry record supplies the broad study design and questionnaire topic, but not the response-level results or analysis procedure. The following concepts are general explanations of what would be relevant to such a comparison; they are not claims about methods actually used in this study.

What a crossover comparison requires

In general, a crossover study exposes a participant to more than one condition, allowing each participant to serve as a reference for their response under another condition. This can reduce the influence of stable differences between participants when the analysis compares their responses across conditions. That benefit depends on the data structure and the analysis reflecting the pairing. Treating paired responses as if they came from unrelated people can misstate uncertainty.

Crossover studies may also be affected by sequence, period, or carryover effects. Sequence refers to the order in which conditions are experienced; period refers to the timing or position of a measurement; carryover describes an influence of an earlier condition on a later response. These are general design considerations, not known features of this trial. The registry record does not report the sequence, a washout interval, period-specific outcomes, or an analysis addressing these effects. The presence or importance of any such effect cannot be inferred from the crossover label alone.

How a preference questionnaire can be analyzed

Questionnaire responses may be categorical, ordered, or numerical, depending on the response options. A categorical response can be summarized as counts or proportions in each category. An ordered scale can preserve the ordering of responses, while a numerical score may be analyzed using a model suited to its distribution. These approaches answer different questions, and their interpretation depends on the scale’s construction. The registry record identifies the outcome as a participant count and describes preference questions, but it does not report the response format, coding, or analysis approach.

If the outcome consists of several preference dimensions, separate analyses could produce separate estimates. A combined score would instead require a defined method for combining responses. The record identifies quickness, efficiency, comfort, and stress but does not say whether these dimensions formed separate outcomes, a composite, or a single categorical question with several options. It reports that the primary outcome has several categories or time points and is not reduced to one comparison. Consequently, no single effect estimate should be inferred from the endpoint title.

Uncertainty and statistical evidence

In general, a confidence interval describes a range of values compatible with the data and the statistical model at a stated confidence level. Its width reflects precision: a wider interval indicates less precision than a narrower interval under the same framework. A p-value, when used, measures how unusual the observed data would be under a specified null model; it is not the probability that the null model is true, nor does it measure the clinical importance of an effect.

No confidence interval, p-value, or effect estimate for the questionnaire is reported in the registry record. The direction and magnitude of an effect therefore cannot be assessed, and its precision cannot be judged. A p-value alone, if reported elsewhere, would not replace an estimate and its uncertainty; likewise, a category count without a comparison and suitable denominator would not establish the size of a preference difference.

Multiplicity and analysis choices

Multiplicity arises when several outcomes, categories, time points, or comparisons are examined. In general, testing many hypotheses can increase the chance of obtaining at least one apparently notable result by chance. Statistical plans may address this by specifying a primary contrast, controlling error across tests, or treating additional analyses as exploratory. Which approach is appropriate depends on the study question and plan.

The registry record does not report a multiplicity procedure, a prespecified contrast among the questionnaire dimensions, or an analysis plan. The outcome is not reduced to a single comparison in the posted information. It is therefore not possible to determine how multiplicity was handled or whether any category-specific finding was designated as primary. No protocol or statistical plan should be inferred from the study design alone.

Planning calculations are not outcome evidence

The stated planning assumptions describe a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The stated effect to detect is a fraction of the observed effect. Such assumptions describe planning illustrations, not a result from the trial. A sample-size illustration based on an observed effect is conditional on that effect and on the assumptions used; it does not demonstrate the probability that this completed study detected a real effect. This is general interpretation, not observed power.

The registry record does not report the observed questionnaire effect needed to understand such illustrations or the trial’s own sample-size justification. It also does not report the target effect or a power calculation used to design the study. Sample-size planning outputs, where displayed, should therefore be read as hypothetical planning quantities rather than as evidence about participant preference or the success of the comparison.

What can be concluded from the posted methods information

The available design details support describing a randomized, unmasked, bilateral crossover dispensing study and its stated questionnaire topic. They do not establish the questionnaire’s scale, the crossover sequence, the statistical model, the analysis population, missing-data handling, multiplicity adjustment, or the outcome result. These are not minor interpretive details: they determine what contrast was estimated, which participants informed it, and how much uncertainty should be attached to it. The registry record does not report them, so a numerical statistical conclusion about preference is not possible.

10. Multiplicity, Missing Data and Analysis Populations

The primary questionnaire description names quickness, efficiency, comfort, and stress. Those are multiple dimensions of preference, and the registry record also indicates that the primary outcome has several categories or time points and is not reduced to one comparison. It does not report whether the dimensions were treated as separate endpoints, combined into a score, or arranged within a prespecified hierarchy. A multiplicity adjustment or strategy for interpreting multiple responses is not reported in the registry record.

In general, when several outcomes or contrasts are examined, the chance of finding an apparently unusual result by chance may increase. A prespecified statistical plan can clarify which comparison is confirmatory and how additional results should be interpreted. The registry record does not report such a plan, so it is not possible to assess whether multiplicity was considered or how any category-specific findings were meant to be interpreted.

The number of participants with a recorded primary outcome is not reported in the registry record. The registry enrollment of 119 does not establish that every enrolled participant completed the questionnaire or contributed to every comparison. The record does not describe missing responses, exclusions, withdrawals, or the method used to handle incomplete data.

The analysis population is also not reported in the registry record. There is no description of whether the primary analysis included everyone randomized, participants completing both conditions, or another defined group. These gaps prevent assessment of how closely the analyzed participants reflect the randomized population and whether missingness or exclusions could affect the preference estimate.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry record lists safety counts separately for R-Refraction and S-Refraction. For each listed group, serious adverse events are 0 among 119 at risk, other adverse events are 0 among 119 at risk, and deaths are 0. No serious adverse event terms are listed.

These figures describe the counts entered in the registry record. In general, “at risk” identifies the number recorded as eligible for the relevant event count; it does not, by itself, explain the duration or completeness of event surveillance. The record does not define the event-collection procedures, the follow-up window for adverse events, or how events were attributed to a condition.

Because the study is described as crossover, the group entries should be read as registry group summaries, not as proof that each entry represents a separate set of people. The record does not explain how participants who experienced both refraction conditions were represented in the safety reporting. The zero counts should not be interpreted as proof that the devices cannot be associated with adverse events, nor do they determine the subjective preference outcome.

12. What the Result Does, and Does Not, Mean

The registry record establishes that the study was completed and describes a randomized, unmasked crossover comparison of refraction and associated spectacle lenses using the Vision R-800 and a standard phoropter. It identifies a final-visit questionnaire about preferences for quickness, efficiency, comfort, and stress. Those details define the topic of the planned assessment, but they do not provide the result of that assessment.

Category-specific response counts, comparative estimates, uncertainty intervals, and p-values are not reported in the registry record. It is therefore not possible to say which condition was preferred, whether preferences differed across questionnaire dimensions, or how precisely any contrast was estimated. Absence of reported results should not be read as evidence of no difference, equal preference, or equivalence.

The record also does not explain the questionnaire response scale, the analysis model, how the crossover pairing was handled, or which participants contributed data. Those details affect the interpretation of any eventual estimate. Enrollment is listed as 119, but outcome completion and the analysis population are not reported. The enrollment figure cannot substitute for an outcome denominator.

The posted safety counts are 0 for serious adverse events, 0 for other adverse events, and 0 for deaths in each listed group. These entries describe registry reporting and do not provide a complete assessment of all possible safety outcomes or explain event surveillance.

Overall, the record permits a description of the design, endpoint topic, and posted safety counts. It does not support a conclusion about the direction, size, statistical significance, or clinical importance of participant preference. Any such conclusion would require outcome results and analysis details that are not reported in the registry record.

13. Why This Trial Matters Statistically

This study is statistically relevant because it asks about a participant-reported experience in a randomized crossover comparison. A crossover design can be useful for questions where each participant can experience both conditions, since within-participant comparisons may account for stable individual differences. This is general design context; the registry record does not report enough detail to determine how that potential advantage was used in the analysis.

The endpoint also illustrates why the definition of an outcome matters. Quickness, efficiency, comfort, and stress are related aspects of experience, but they are not necessarily interchangeable. A clear analysis needs to say whether they are separate outcomes or components of a combined measure, how responses are coded, and which contrast is central. Those definitions are not reported in the registry record, and no category-specific results are posted.

Statistical significance and practical meaning would require more than a label of “preference.” A comparative estimate would indicate the direction and size of a difference, and an uncertainty interval would show its precision. Without the results and the analysis method, neither can be assessed. This makes the record a useful example of the distinction between a registered research question and a fully interpretable result.

The safety entries also illustrate the limits of simple event counts. The registry lists zero counts in both groups, but those counts need context about collection, follow-up, definitions, and crossover attribution. Statistical interpretation depends not only on the number recorded but on how that number was generated.

Finally, the record highlights the importance of reporting analysis populations, missing responses, and multiplicity decisions for questionnaire outcomes. Without these, readers cannot establish how complete the evidence is or how to interpret findings across several preference dimensions. The design is identifiable; the statistical result is not available in the registry record.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation for interpreting this trial from the registry record is the absence of primary outcome results. The record names a subjective questionnaire and its preference dimensions but does not report response counts, comparative estimates, uncertainty intervals, or p-values. Direction, magnitude, and precision therefore remain unknown.

The endpoint is not fully specified. The record does not give the question wording, response options, scoring rules, or whether the dimensions were analyzed separately or combined. Without these details, the intended estimand—the precise quantity the analysis was meant to estimate—cannot be reconstructed. The posted information also indicates that the primary outcome has several categories or time points and is not reduced to one comparison.

Although the study is described as randomized and crossover, the sequence, period structure, and any washout procedures are not reported in the registry record. The statistical model and handling of within-participant dependence are also not reported. These omissions limit assessment of whether the analysis matched the design and whether order or carryover effects were considered.

Registry enrollment is 119, but the number with outcome data and the analysis population are not reported. Missing responses, withdrawals, exclusions, and their handling are not described. Multiplicity procedures and the statistical analysis plan are not reported, and the record does not provide the trial’s own sample-size justification.

For safety, the record supplies zero event counts in each listed group but does not describe event definitions, surveillance duration, or attribution in a crossover setting. The record also lists PHASE4 while the official title includes “Phase 2”; the reason is not reported. These limitations concern what can be concluded from the registry record and do not establish that the underlying study lacked these procedures or data.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Clinical Investigation of the Vision-R800 Device. — NCT04208750.
• Registry record last updated 2022-03-14; status last verified 2022-02.
• Results first posted 2022-03-14.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record describes NCT04208750, “Clinical Investigation of the Vision-R800 Device,” as a completed, randomized, unmasked, bilateral crossover dispensing study. It lists the Vision R-800 Phoropter and Standard Phoropter and describes refraction with associated spectacle lenses. Registry enrollment is 119. Conditions listed are myopia, hyperopia, astigmatism, and presbyopia.

The primary outcome is “Subjective Questionnaire Response,” assessing preference for quickness, efficiency, comfort, and stress at Visit 5 (final visit), up to 5 weeks. Category-specific outcome results and the analysis details are not reported in the registry record. Safety entries list 0 serious adverse events, 0 other adverse events, and 0 deaths in each group, with 119 at risk in each listed group.

The record lists PHASE4, while the official title includes “Phase 2”; the record does not explain this difference. The listed start date is 2019-11-18, and the primary completion date is 2021-02-01.