Evaluate the Safety and Effectiveness of The Tixel Fractional System in the Treatment of Meibomian Gland Disfunction: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluate the Safety and Effectiveness of The Tixel Fractional System in the Treatment of Meibomian Gland Disfunction (NCT04889950), a randomized na study. The primary outcome is Score and Change From Baseline in Tear Break Up Times (TBUT), as Assessed by a Masked Rater.

2. Clinical Question

This is a comparison of two device-based treatment schedules in a pilot study, not a comparison with no treatment. The arms also differ in the number of sessions and in the time from baseline to the primary follow-up examination. Those design features matter when interpreting any comparison: an arm difference would reflect the assigned treatment strategy and its schedule, assessed at the specified follow-up time. The outcome results needed to quantify that comparison are not reported in the registry record.

3. Trial Design

The registry describes a prospective, randomized, controlled, evaluator-masked pilot study of Tixel versus LipiFlow for meibomian gland dysfunction. It records a parallel-group design and single masking. The masked role is identified as the evaluator; participants’ masking status is not reported in the registry record. The study is listed as completed, with recorded enrollment of 30. The brief description states that up to 30 patients, representing 60 eyes, were to be randomized at up to 2 clinical sites in Israel and/or Europe. The actual number randomized and the actual number enrolled at each site are not reported in the registry record.

The Tixel group was assigned three treatment sessions at monthly intervals, followed by follow-up visits 1 month and 3 months after the final treatment. The LipiFlow group received one treatment, followed by the same stated follow-up intervals after that treatment. The primary tear break-up time assessment used a different scheduled time from baseline in the two arms: 8 weeks post baseline for Tixel and 4 weeks post baseline for LipiFlow. Thus, the primary assessments occurred 4 weeks after each arm’s final treatment but not at the same elapsed time from baseline.

The registry records a study start date of 2021-10-26 and a primary completion date of 2023-01-04. It lists secondary outcomes that include symptom scores, meibomian gland scores, tear break-up time, discomfort and pain questionnaires, staining scores, and intraocular pressure. The registry identifies 9 outcome measures, but does not report outcome estimates or the results of statistical analyses. The number of participants completing the primary examination is reported as 10 in each arm.

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

Analysis population for the primary outcome, as defined in the registry: 10 Tixel subjects and 10 LipiFlow subjects completed the Baseline and 4-week FU TBUT examination.

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.

Population: study subjects comparing the Tixel device to LipiFlow System

6. Primary Endpoint

The registry lists the primary outcome as Score and Change From Baseline in Tear Break Up Times (TBUT), as Assessed by a Masked Rater, measured over Tixel arm: Baseline and 4 weeks after last treatment (8 weeks post baseline). LipiFlow arm: Baseline and 4 weeks after treatment (4 weeks post baseline)..

The primary endpoint is change from baseline in tear break-up time, abbreviated TBUT, assessed by a masked rater. TBUT measures how long it takes for dry spots to appear on the cornea after a blink. It is used to assess tear-film stability: a shorter time indicates a less stable tear film and can be associated with dry eye or other ocular-surface disorders. The registry specifies seconds as the unit and describes the endpoint as a mean with a 95% confidence interval.

The endpoint compares the follow-up value with the participant’s baseline value, rather than relying on the follow-up measurement alone. Change from baseline can help account for differences in starting measurements, although how baseline values were incorporated into the statistical analysis is not reported in the registry record. The registry describes follow-up as 4 weeks after the last treatment in each arm. Because the Tixel group received three sessions and the LipiFlow group received one, those examinations occurred at different times from baseline: 8 weeks post baseline for Tixel and 4 weeks post baseline for LipiFlow.

The record includes general interpretive ranges for TBUT, but does not report the observed baseline values, follow-up values, mean changes, or confidence intervals. Consequently, the endpoint’s clinical measurement is described, but its observed result cannot be interpreted from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean change represent? The primary measure is continuous: TBUT is recorded in seconds, and the endpoint is change from baseline. A mean change summarizes the average participant-level change in a group. It can be useful for describing the overall pattern, but it does not show how changes were distributed across individuals. Some participants may change more than others, and a group mean alone cannot describe that spread. General statistical interpretation therefore considers both the estimated mean and its uncertainty, along with the amount and pattern of missing data.

The registry specifies a 95% confidence interval for the primary measure. In general, a confidence interval expresses the range of estimates reasonably compatible with the observed data under the analysis assumptions. It is not a guarantee that the true value lies in a particular interval, nor does it by itself determine clinical importance. The actual mean changes and confidence intervals are not reported in the registry record, so their magnitudes and precision cannot be discussed.

Why does masking matter?

The study is described as evaluator-masked. Masking the person who assesses an outcome can reduce the risk that expectations influence measurement or scoring. That is relevant for a clinical assessment such as TBUT, even when the measure is recorded in seconds. The registry does not report how masking was maintained, whether it was successful, or whether participants or treatment staff were masked. Those details are not reported in the registry record, so the scope of masking cannot be assessed beyond the evaluator designation.

What does randomization contribute?

Random allocation is intended to make the treatment groups comparable, on average, with respect to both measured and unmeasured characteristics at the start of a study. In small pilot studies, chance imbalances can still occur. The registry states that allocation was randomized, but does not report the allocation procedure, concealment method, or baseline outcome values. It is therefore not possible to evaluate the achieved balance or the details of allocation from this record. Randomization supports a comparative design, but it does not replace reporting the treatment estimates and their uncertainty.

How should the scheduled follow-up be considered?

Both groups were examined 4 weeks after their final treatment. The schedules differed, however: Tixel involved three monthly sessions and its primary examination was 8 weeks post baseline, while LipiFlow involved one session and its examination was 4 weeks post baseline. A comparison at those specified assessments would not represent measurement at a common time from baseline. This matters because an outcome can change over time, irrespective of the treatment contrast. The registry does not report a separate analysis at a common baseline-to-follow-up interval or explain how the timing difference was handled.

What can the sample-size planning illustrate?

The record describes sample-size planning illustrations based on a fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. In general, such illustrations explore how the number of participants per arm depends on the effect size selected for detection and the assumptions used. They are not observed study results and should not be interpreted as observed power. The registry does not report the trial’s own sample-size justification. The primary outcome also has several categories or time points and is not reduced to one comparison in the posted results, so a single primary effect estimate cannot be used to evaluate the planning illustration from the record alone.

For continuous outcomes, general sample-size calculations depend on the target effect, variability, significance level, power target, and allocation assumptions. A smaller effect to detect generally requires more participants than a larger effect, all else being equal. These are planning principles, not findings from this study. No resulting participant-per-arm planning values are reported in the registry record, and no calculation can be verified from the available primary outcome results because those results are absent.

Why do analysis details matter?

A statistical analysis plan would clarify the primary contrast, the handling of baseline measurements, the model or test, and the treatment of missing outcomes. The registry record does not report those details. It also lists no analysis results. Consequently, the reported endpoint definition cannot be connected to a specific inferential procedure, and assumptions such as distributional form or variance structure cannot be assessed. As a general matter, if continuous outcomes show more variability than a model assumes, standard errors and confidence intervals may be unreliable; the appropriate response depends on the data and planned model. No evidence in the registry record establishes that over-dispersion occurred or that any particular adjustment was used.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists multiple outcome measures, including TBUT, symptom scores, gland scores, discomfort and pain assessments, staining measures, and intraocular pressure. Examining several outcomes or time points can raise a multiplicity issue: when many hypotheses are tested, the chance of at least one apparently unusual result can increase. General approaches include identifying a primary comparison in advance, adjusting inference across tests, or treating secondary findings as exploratory. The registry record does not report a multiplicity strategy, a hierarchy among the outcomes, or which secondary comparisons were designated for confirmatory inference.

The primary TBUT description refers to baseline and follow-up, while the study also includes additional follow-up visits. The record states that the endpoint has several categories or time points and is not reduced to one comparison in the posted results. It does not report which time point or contrast was used in an analysis, or whether repeated measurements were modeled together. Without that information, it is not possible to determine how the multiple measurements were handled statistically.

Missing-data reporting is also limited. The primary outcome description says that 10 Tixel subjects and 10 LipiFlow subjects completed the baseline and 4-week follow-up TBUT examination. Although the recorded enrollment is 30, the participant flow and reasons that other participants may not have contributed to this endpoint are not reported in the registry record. The analysis population, such as whether analyses included all randomized participants or only those with completed measurements, is not reported. Nor are the missing-data assumptions, imputation methods, or sensitivity analyses described. In general, missing outcomes can affect estimates if the chance of missingness is related to treatment or to the unobserved outcome. The registry does not provide enough information to assess that possibility in this study.

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.

Most frequent non-serious adverse event terms

The safety record lists zero serious adverse events in the Tixel group among 11 participants at risk and zero in the LipiFlow group among 10 participants at risk. It also lists zero deaths in each group. These are the serious-event and death counts recorded for the study; they should not be read as proof that no such events could occur, or as a comparison establishing equivalent safety.

For other adverse events, the registry lists 4 affected participants in the Tixel group and 3 in the LipiFlow group, using the same at-risk counts of 11 and 10. These are counts of participants affected, not a description of event type, severity, timing, or relationship to treatment. The registry does not report the individual event terms, whether participants could have experienced more than one event, or how events were assessed for causality. It also does not report a statistical comparison of the safety counts.

Small safety counts can be imprecise, and differences in counts alone do not establish a difference in risk. General interpretation requires the underlying event definitions, follow-up completeness, and suitable uncertainty estimates. Those details are not reported in the registry record. The counts should therefore be read as a limited descriptive account of events recorded in each arm, not as a stand-alone estimate of comparative safety.

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

The registry record establishes that a randomized, evaluator-masked pilot study compared a three-session Tixel schedule with a single LipiFlow treatment schedule. It defines the primary outcome as change from baseline in TBUT and identifies the number of participants who completed the specified TBUT examinations. It also reports selected safety counts. These are useful features for understanding what the study set out to assess and what information was recorded.

The record does not report the primary outcome estimates. There is no reported mean change by arm, confidence interval, or direct between-arm estimate. Without those quantities, the direction, size, and precision of the TBUT result cannot be assessed. The registry record also does not report a p-value or analysis method for the primary outcome. The absence of a result in the registry is not evidence that there was no effect; it means that the comparative result is not available in this record.

The study’s timing also limits what a simple treatment comparison would mean. The primary assessments were each scheduled 4 weeks after the arm’s final treatment, but occurred at 8 weeks post baseline in the Tixel arm and 4 weeks post baseline in the LipiFlow arm. The record does not report an analysis that separates treatment strategy from elapsed time since baseline.

The adverse-event counts are descriptive and do not establish causation or comparative safety. Likewise, recorded enrollment and endpoint completion counts do not explain participant flow or the handling of missing outcomes. The analysis population and statistical plan are not reported in the registry record.

Accordingly, the posted information describes the trial’s question and selected design and safety details, but does not support a conclusion about which treatment produced a larger TBUT change. It also cannot establish that the treatments are equivalent or that either treatment is effective or ineffective. Those conclusions require outcome estimates, uncertainty, and analysis details that are not reported in the registry record.

13. Why This Trial Matters Statistically

This study is statistically instructive because it combines a randomized comparison with a pilot-scale sample and different treatment schedules. Randomization is an important design feature for comparative inference, while evaluator masking can reduce the influence of expectations on outcome assessment. At the same time, the number of participants contributing to the primary examination is limited, and the registry does not report the resulting estimates or their uncertainty. The record therefore illustrates why a well-defined design does not, by itself, provide enough information to judge an observed treatment contrast.

The follow-up timing raises a further interpretive issue. Each group’s primary examination was scheduled 4 weeks after its final treatment, but the number of treatments differed, so the examinations occurred at different times from baseline. This highlights the importance of defining the estimand—the exact quantity a comparison is intended to estimate—including the treatment schedule, follow-up time, and outcome contrast. The registry describes these components but does not report a single analyzed comparison.

The record also illustrates why participant flow and analysis populations matter. The enrolled total is 30, whereas 10 participants in each arm are identified as having completed the primary examinations. Without a flow account or missing-data methods, readers cannot determine how endpoint completion may affect the estimate. General principles of transparent reporting call for the number analyzed, reasons for missing data, the planned statistical method, and uncertainty around the estimate.

Finally, the safety figures demonstrate the difference between descriptive counts and comparative inference. Counts of serious and other adverse events are informative as a record of reported events, but do not alone quantify uncertainty or establish causation. For a pilot study, clear estimates and limitations are particularly important: the design may help frame questions for further study, but the registry’s available results do not quantify a TBUT treatment contrast.

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 primary limitation is that the registry does not report the primary TBUT results. Although it specifies a mean change and a 95% confidence interval, neither arm-specific estimates nor a comparative estimate are available. The record also does not report a test result or analysis method. As a result, the magnitude and precision of the primary outcome cannot be evaluated.

The reported primary endpoint completion count is 10 participants in each arm. The registry records enrollment of 30, but does not provide participant flow, reasons for non-completion, or the number included in each secondary outcome. This limits assessment of missing-data bias and the populations represented by the posted results. The analysis population and any sensitivity analysis are not reported in the registry record.

The primary assessment timing differs from baseline between arms: 8 weeks post baseline for Tixel and 4 weeks post baseline for LipiFlow, although both are scheduled 4 weeks after the last treatment. This makes the intended between-arm contrast dependent on distinct treatment schedules and assessment times. The record does not describe an analysis that accounts for that timing difference.

Further limitations include the lack of reported details on randomization procedures, allocation concealment, baseline outcome values, and how evaluator masking was maintained. The registry does not report a statistical analysis plan, multiplicity handling, or methods for repeated measurements. It lists multiple outcome measures, but does not report their results or clarify which comparisons were confirmatory. Safety reporting includes counts but not event terms, severity details, causality assessments, or uncertainty estimates. These omissions limit interpretation of both efficacy-related measurements and safety data.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluate the Safety and Effectiveness of The Tixel Fractional System in the Treatment of Meibomian Gland Disfunction — NCT04889950.
• Registry record last updated 2024-11-15; status last verified 2024-11.
• Results first posted 2024-11-15.
• 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

NCT04889950 is a completed randomized, evaluator-masked, parallel-group pilot study of Tixel and LipiFlow for meibomian gland dysfunction. The registry records enrollment of 30. The Tixel group received three treatment sessions at monthly intervals; the LipiFlow group received one treatment. The primary endpoint was change from baseline in TBUT, assessed by a masked rater. The primary follow-up was 8 weeks post baseline for Tixel and 4 weeks post baseline for LipiFlow. The registry reports that 10 participants in each arm completed the specified TBUT examinations, but does not report the outcome estimates or statistical analysis results. Serious adverse events and deaths are listed as zero in both groups; other adverse events affected 4 participants in the Tixel group and 3 in the LipiFlow group. The registry does not report participant flow, analysis populations, or details of the statistical analysis plan.