Mechanisms of Light-based Therapies for Dry Eye Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Mechanisms of Light-based Therapies for Dry Eye Disease (NCT06004895), a randomized na study. The primary outcome is Change From Baseline in Non-invasive Tear Break Up Time to the Final Follow-up 3 Months After Final Treatment Session.

2. Clinical Question

The registry summary frames the study as an investigation of short- and longer-term changes associated with light-based treatments for dry eye disease and meibomian gland dysfunction. It also asks whether LLLT alone performs better than IPL combined with LLLT. However, the posted arm summaries identify actual IPL plus LLLT and sham IPL plus LLLT. A separate LLLT-only outcome arm is not reported in the registry record, so the posted primary results do not directly present the LLLT-alone comparison described in the summary.

The primary endpoint is a tear-stability measure in seconds. Results are reported as a mean change from baseline for each arm, rather than as a direct estimate of the difference between arms. That distinction matters: the arm-specific means describe changes within each group, while a treatment comparison requires a between-arm estimate and its uncertainty.

3. Trial Design

The registry identifies this as a randomized, triple-masked, parallel trial. Its listed enrollment is 26, and the status is completed. The phase is recorded as NA. The sponsor is Aston University. The posted primary outcome summaries list 24 participants in each arm; the registry record does not explain how those arm counts relate to the enrollment figure.

The two outcome arms are Actual IPL and LLLT, and Sham IPL and LLLT. The description of actual IPL refers to pulses delivered along the lower-lid region, with LLLT delivered using a wearable facial mask with red LEDs. The sham description refers to an empty IPL cartridge at the lower eyelid while a working cartridge simulates a pulse directed away from the participant’s face. The registry labels the overall design parallel, while its summary also describes treatment being directed to one eye and the other eye. The record does not explain how those descriptions fit together, so the design should be read from the formal classification and the posted arm descriptions without assuming an unreported allocation structure.

The registry summary describes four treatment sessions, each separated by two to three weeks, followed by assessments two to three weeks and three months after the final session. The primary endpoint timeframe is baseline and three months after the final treatment session, up to six months after baseline. The specific masking roles, allocation procedure, and rationale for the planned enrollment are not reported in the registry record.

The primary outcome is change in non-invasive tear break-up time. The registry also lists several secondary outcomes, including symptom scores, tear meniscus height, lipid layer pattern, conjunctival hyperaemia, blinks, visual acuity, and corneal staining. Results for those additional measures should not be inferred from the primary endpoint estimates.

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.

Before assignment: This is a paired eye randomised clinical trial, that is one eye of a participant is randomised to being treated with actual IPL and LLLT, while the other eye of the same participant is randomised to being treated with Sham IPL and LLLT. Hence, 26 participants were recruited, with 26 eyes randomised to having the first treatment, while the contralateral 26 eyes were randomised to the second treatment.

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 Change From Baseline in Non-invasive Tear Break Up Time to the Final Follow-up 3 Months After Final Treatment Session, measured over Baseline and 3 months after final treatment session (up to 6 months after Baseline).

Non-invasive tear break-up time measures tear-film stability: the time, in seconds, before the tear film begins to break up. The registry describes it as an indicator of tear stability and how quickly tears evaporate. Measurements were made with the Oculus Keratograph 5M instrument, and the recorded value is an average of three measurements.

The primary endpoint is the change from baseline to the final follow-up three months after the last treatment session. Its timeframe is also described as up to six months after baseline. Reporting change gives a measure of how the endpoint differs from its starting value over the treatment and follow-up period. The registry gives a mean change for each arm, with a 95% confidence interval.

As a continuous measure, tear break-up time can retain information about the size of a change rather than reducing observations to categories. The average of repeated measurements is intended to represent the measured tear stability at an assessment; it does not show the spread of individual participant values. The registry does not report the direction convention used to calculate change, so the negative estimates should be described as negative changes rather than assigned a clinical interpretation based on sign alone.

This endpoint addresses tear-film stability, one aspect of dry eye disease. It does not by itself capture symptoms, every feature of ocular surface health, or the full range of secondary outcomes listed in the registry.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous and is summarized by a mean change from baseline in seconds. A mean gives the arithmetic average of the observed changes in an arm. It describes the group’s central change but does not show whether participants had similar changes or a wide range of responses. The registry does not report a standard deviation or another measure of participant-level spread for this endpoint.

What does the confidence interval describe?

The 95% confidence interval accompanies each arm’s mean change. In general, a confidence interval communicates the precision of an estimate under the statistical method used: narrower intervals indicate greater precision, while wider intervals indicate more uncertainty. It does not mean that 95% of participants had changes inside the interval. Nor is an arm-specific interval, by itself, a confidence interval for the difference between arms.

The Actual IPL and LLLT mean is -2.61 seconds, with limits of -5.91 and 0.69. The Sham IPL and LLLT mean is -0.85 seconds, with limits of -3.31 and 1.62. Each interval crosses zero. This means the reported intervals include no mean change, alongside values on either side of zero. It does not provide a test of whether the arms differ. A direct comparison would need an estimate of the between-arm contrast and its uncertainty, which is not reported for this endpoint.

Why is a direct comparison important?

Within-arm changes describe what was observed in each group relative to baseline. The treatment question, however, concerns whether the change differs between the actual-IPL and sham-IPL arms, with LLLT included in both. A between-arm estimate accounts for the fact that each group has its own observed change and sampling uncertainty. The registry record says that values are missing or not estimable for a two-arm comparison of this continuous endpoint. No recalculated contrast, p-value, or comparative confidence interval is therefore available in the posted results.

In general, overlap or non-overlap between two separate confidence intervals is not a substitute for the confidence interval or test of the difference between groups. The two arm estimates are useful descriptive results, but they should not be turned into a comparative result by subtracting one mean from the other. No such calculation is reported in the registry record.

What does the planning illustration mean?

The record describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect. The planning values and the fraction used are not reported in the registry record. Such calculations are illustrations of the participant numbers that might be needed under specified assumptions; they are not observed power and do not show the probability that the completed trial detected an effect.

More generally, power calculations depend on assumptions about the effect size, variability, allocation, and analysis. If those assumptions do not match the eventual study or target question, a planning illustration may not describe the actual precision of the results. The record does not report the trial’s own sample-size justification, and the planning illustration should not be treated as evidence that the design was adequate or inadequate.

How should multiple outcomes be considered?

The registry lists 31 outcome measures and 24 secondary outcomes, but no analysis entries. When many outcomes are assessed, general statistical practice considers how to manage the chance of identifying apparently notable findings among numerous comparisons. Possible approaches depend on the prespecified hierarchy and analysis plan. The registry record does not report whether a multiplicity strategy was planned or used, and it does not provide a statistical analysis plan that would clarify the intended primary and secondary comparisons.

Other important analytic details are also not reported in the registry record, including the method for handling missing observations, the exact analysis population, any covariate adjustment, and whether the confidence intervals use a particular model or variance assumption. These omissions mean that the posted summary statistics can be described, but their detailed analytic derivation cannot be reconstructed from the registry record alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 31 outcome measures, of which 24 are posted as secondary outcomes. These include measures of symptoms, tear meniscus height, lipid layer pattern, conjunctival hyperaemia, blinks, visual acuity, and corneal staining. Assessing multiple endpoints can raise multiplicity concerns: as a general statistical matter, the chance of obtaining an apparently unusual result can increase when many comparisons are made. The registry record does not report an adjustment method, an outcome hierarchy, or a plan for interpreting results across this set of measures.

The record contains no analysis entries. For the primary outcome, arm-specific means and confidence intervals are posted, but a two-arm comparison is not estimable in the posted results. No comparative p-value or confidence interval is reported. Results for the secondary outcomes are not included in the outcome details available for this analysis, so their estimates and uncertainty should not be inferred.

Missing-data procedures and the primary analysis population are not reported in the registry record. The summaries list 24 participants in each arm, while enrollment is listed as 26; the record does not explain the relationship between these counts. It is therefore not possible to determine from the posted information whether the summaries use all randomized participants, participants with available measurements, or another defined group. The record also does not state how missing baseline or follow-up measurements were handled.

The registry does not report whether the analysis was intention-to-treat, per-protocol, or based on another population. It does not report imputation, sensitivity analyses, or rules for excluding observations. These details matter because missing measurements or analysis-population choices can affect estimates and their interpretation. In their absence, the posted means and confidence intervals should be read as the registry’s reported summaries, without assuming an unreported analysis method.

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 posted safety counts list 24 participants at risk in each arm. For Actual IPL and LLLT, the number with a serious adverse event is 0, the number with another adverse event is 0, and deaths are 0. For Sham IPL and LLLT, the corresponding counts are also 0, 0, and 0. No serious adverse-event terms are listed.

These figures describe the events recorded in the registry’s safety summaries. They do not establish that the treatments have no risks. A zero count in a trial summary is not proof that an event cannot occur, and the registry record does not report the adverse-event collection period, definitions, severity grading, or event-specific surveillance procedures. Nor does it explain the relationship between the 24 participants at risk in each arm and the total enrollment of 26.

The figures should therefore be read narrowly: no serious adverse events, other adverse events, or deaths are recorded in these arm summaries. They do not provide a comprehensive account of possible harms beyond the reporting and observation described in the registry record, and the record does not report further detail that would allow a fuller assessment.

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

The posted primary results describe mean changes in non-invasive tear break-up time for two arms: actual IPL plus LLLT and sham IPL plus LLLT. Both arm-specific confidence intervals include zero. This indicates uncertainty about the direction and size of the average change in each arm; it does not establish that the arms had the same outcome or that one differed from the other.

The most important distinction is between a change within an arm and a contrast between arms. The reported means describe each arm’s change relative to baseline. A comparative treatment effect would require a direct estimate of how those changes differ, together with its uncertainty. The registry record does not report an estimable two-arm comparison for this continuous endpoint. The arm means should not be used as a substitute for that missing comparative result.

The results also do not answer every question in the registry summary. In particular, the summary asks whether LLLT alone is better than IPL plus LLLT, but the posted primary outcome arms are actual IPL plus LLLT and sham IPL plus LLLT. A separate LLLT-only outcome arm is not reported in the registry record. The primary endpoint also captures tear-film stability, not all symptoms or other aspects of dry eye disease and meibomian gland dysfunction.

These findings should not be treated as a full account of the trial’s prespecified analyses. The registry lists many outcome measures but no analysis entries, and it does not report the missing-data strategy, analysis population, or multiplicity approach. Those absences limit interpretation of the primary endpoint and prevent a broader synthesis of secondary outcomes from the posted information.

The safety summaries record zero serious adverse events, zero other adverse events, and zero deaths in each arm. Those counts are descriptive and do not prove the absence of risk. Overall, the posted data provide arm-level estimates with substantial uncertainty, while the comparative estimate needed to assess the central actual-versus-sham IPL question is not reported.

13. Why This Trial Matters Statistically

This trial is statistically interesting because the registry summary presents a mechanistic question about light-based treatments, while the posted primary endpoint is a quantitative measure of tear-film stability. A continuous endpoint can describe the magnitude of change in seconds, and the registry specifies that the instrument measurement is based on an average of three readings. This gives a concrete way to characterize one aspect of ocular surface response over follow-up.

At the same time, the posted results illustrate why arm-specific change estimates are not enough for a randomized comparison. The two means and their confidence intervals describe changes within the actual-IPL and sham-IPL arms. The direct two-arm comparison is not estimable in the posted results, so the primary endpoint does not quantify the contrast that would address whether adding actual IPL changes outcomes when LLLT is used in both arms.

The record also raises questions about alignment between the summary question and the results presented. It mentions LLLT alone versus IPL plus LLLT, while the posted arms are actual IPL plus LLLT and sham IPL plus LLLT. Clarifying which comparison was planned and which outcomes were analyzed would be important for connecting the trial’s stated question to its results.

Finally, many outcomes are listed, but the registry does not report an analysis plan, missing-data methods, analysis population, or approach to multiplicity. These are central details for interpreting a study with multiple endpoints. The record’s limitations are not merely technical: they determine how confidently readers can distinguish a descriptive change from evidence about a 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 outcome summaries give means and 95% confidence intervals but do not report the standard deviation or participant-level data. The intervals describe uncertainty around the means, but the registry record does not specify the detailed method used to construct them. The direction convention for calculating change is also not reported, limiting interpretation of the negative signs beyond identifying the estimates as negative changes.

The registry does not provide an estimable two-arm comparison for the continuous primary endpoint. Consequently, there is no posted comparative estimate or uncertainty interval for actual IPL versus sham IPL when both arms receive LLLT. The outcome summaries list 24 participants in each arm, while total enrollment is 26, and the record does not reconcile those counts or define the analysis population.

There is also a mismatch between the comparison stated in the registry summary and the posted primary outcome arms. The summary asks about LLLT alone versus IPL plus LLLT; the posted results identify actual IPL plus LLLT and sham IPL plus LLLT. A separate LLLT-only outcome arm is not reported in the registry record. The formal design is described as parallel, while the summary describes treatment to one eye; the record does not explain that relationship.

Although 31 outcome measures and 24 secondary outcomes are listed, no analysis entries are reported. The registry record does not state how missing data were handled, whether multiple comparisons were addressed, or what analysis population was used. The description of adverse events also lacks detail on definitions and collection period. These omissions constrain interpretation of both efficacy-related estimates and safety counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Mechanisms of Light-based Therapies for Dry Eye Disease — NCT06004895.
• Registry record last updated 2026-02-05; status last verified 2026-01.
• Results first posted 2025-07-23.
• 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 identifies a completed, randomized, triple-masked, parallel trial sponsored by Aston University, with enrollment listed as 26. It concerns dry eye syndromes and meibomian gland dysfunction. The primary endpoint is change in non-invasive tear break-up time from baseline to three months after the final treatment session.

For Actual IPL and LLLT, the mean change was -2.61 seconds, with a 95% confidence interval from -5.91 to 0.69. For Sham IPL and LLLT, it was -0.85 seconds, with a 95% confidence interval from -3.31 to 1.62. Both intervals include zero, and a direct two-arm comparison is not reported as estimable. Safety summaries record zero serious adverse events, zero other adverse events, and zero deaths in each arm. The record does not report key analytic details, including missing-data methods, the analysis population, or multiplicity handling.