Evaluating Contact Lens Optics: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluating Contact Lens Optics (NCT05028790), a randomized na study. The primary outcome is Visual Performance.

2. Clinical Question

3. Trial Design

This was a randomized, single-masked, crossover study of contact lens optics in participants with myopia. Its registry status is completed, and the recorded enrollment is 16. The registry dates the study start as 2022-02-27 and primary completion as 2022-12-13. The study is listed as phase NA, which is consistent with its evaluation of contact lens devices rather than a drug phase.

The crossover structure is central to interpreting the study. Participants were assigned to one of two sequences: single vision soft contact lens first and multifocal soft contact lens second, or the reverse. Each participant was described as wearing both types of lens. This design can allow comparisons within the same participant, but a suitable analysis would generally need to account for the paired observations and the sequence or period structure. The registry record does not report whether or how those features were incorporated in an analysis.

The masking entry says single, but who was masked is not reported in the registry record. Further details about the period lengths, order implementation, any washout, or other conduct of the crossover are also not reported. These details matter because they can clarify how observations were collected and whether effects related to order or time were considered.

The primary result is posted under lens groups of 9 and 7, while each of the numerical secondary refractive error results has 16 observations for each lens. The record does not explain the different counts. There are no reported analyses in the record, so the posted tables should be read as summaries and unadjusted comparisons rather than as a complete account of the study's statistical analysis.

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.

First Intervention (40 Mins)

Washout (5 Mins)

Second Intervention (40 Mins)

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 Visual Performance, measured over Through completion of study visit, an average of 2.5 hours.

The primary endpoint is visual performance, measured as low contrast visual acuity and expressed in logMAR. The registry says this measurement was taken for each participant while wearing each of the two lenses, through completion of the study visit, averaging 2.5 hours. This makes the outcome a measure of visual performance under the lens conditions described in the study.

As general context, visual acuity measures can summarize how clearly a person resolves visual targets under specified testing conditions. Low contrast testing examines acuity where the target is less distinct from its background than in a high contrast test. Such a measure can be useful when the research question concerns visual performance rather than only a refractive measurement. That is a general explanation of the type of endpoint; the registry does not describe the testing protocol in further detail.

On the logMAR scale, lower values conventionally indicate better acuity. The posted means are 0.23 for the single vision lens entry and 0.38 for the multifocal lens entry, with standard deviations of 0.08 and 0.12, respectively. These are descriptive summaries, not a reported paired treatment effect. The registry does not post a primary confidence interval, p value, or analysis that accounts for the crossover structure. The observed means therefore should not be treated as a definitive estimate of the difference between lenses.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes continuous outcomes summarized by means and standard deviations. A mean is the average of the observations in a group. A standard deviation describes how spread out those observations are around the mean; it is not a confidence interval and does not directly show how precisely the mean or a between-condition contrast has been estimated. The primary outcome uses logMAR, while the secondary refractive error outcomes use diopters.

What does the crossover design imply for analysis?

In a crossover study, each participant receives or experiences more than one condition. That creates a natural within-participant comparison: outcomes from the same person tend to be related. General statistical practice is to account for that relationship rather than treating all observations under each condition as if they came from unrelated people. A paired analysis or an appropriate model can use the within-person information and may also address period and sequence effects where relevant. The registry confirms two randomized sequences but does not report a paired analysis, a model, or handling of sequence and period. The posted comparisons therefore cannot be assumed to reflect a crossover-specific analysis.

The primary outcome entries have 9 observations for the single vision lens and 7 for the multifocal lens. The secondary entries each list 16 observations for both lenses. These counts are reproduced as posted; the reason for their difference is not reported in the registry record. Because the primary description says measurements were made for each participant in both conditions, the count discrepancy is particularly important when judging how representative the primary summaries are and whether observations were paired.

How should estimates and intervals be read?

A mean difference expresses the contrast between two group means in the units of the outcome. The secondary comparisons are identified as mean differences, with the multifocal lens as the compared condition and the single vision lens as the control. A confidence interval describes a range of values reasonably compatible with the data and the method used to calculate it. Its width reflects precision: a narrower interval indicates greater precision under that method, while a wider interval indicates less. The registry does not state the confidence level for the posted intervals, so no particular level should be assumed from this record alone.

A p value describes how unusual data at least as inconsistent with a null hypothesis would be under the assumptions of a specified statistical test. It is not the probability that the null hypothesis is true, and it does not measure the size or practical importance of an effect. The secondary p values are labeled unadjusted. They do not account for the fact that several secondary outcomes are examined. The registry does not identify a multiplicity adjustment or provide sponsor-reported analyses.

For the primary endpoint, the registry posts group means and standard deviations but no comparison estimate, interval, or p value. It is therefore not possible to describe the precision of a primary contrast from the record. The observed spread in each group is not a substitute for an interval around the difference, especially in a crossover design where within-person variability and correlation would matter.

Why can over-dispersion matter?

General explanation: when count data vary more than a model assumes, standard errors may be too small and intervals or tests may be misleading unless the extra variation is addressed. The outcomes in this study are continuous, not counts, so over-dispersion is not the principal issue identified by the posted results. For these data, the more immediate methodological questions are the within-participant structure, the unequal primary counts, and the lack of a reported analysis plan. This distinction illustrates why methods should match the data type and design.

What do the planning illustrations represent?

The sample-size illustrations are planning calculations based on observed secondary effects, not the trial's own design rationale. The record states assumptions of a two-sided significance level of 0.05, equal allocation, a normal approximation, and detection of a stated fraction of the observed effect. The displayed rows show participants per arm for 80% power and participants per arm for 90% power at the listed effect fractions. These are hypothetical future-planning quantities. They are not observed power, do not establish that the original study had adequate power, and should not be interpreted as the enrollment target used for this study. The original sample-size justification is not reported in the registry record.

The registry lists no reported analyses. The secondary comparisons and planning calculations displayed on the page are thus best understood as analytical summaries and illustrations, not as a full account of a prespecified statistical analysis. Whether the investigators used other models, handled missing values, or conducted additional analyses is not reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Single Vision Contact Lens", "Multifocal Contact Lens")
n   <- c(9, 7)
m   <- c(0.23, 0.38)
sp  <- c(0.08, 0.12)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Single Vision Contact Lens  9  0.230  0.080  0.169  0.291
CARM  Multifocal Contact Lens  7  0.380  0.120  0.269  0.491

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies one primary outcome and lists five secondary outcome names. Several outcomes create a multiplicity concern: when multiple hypotheses are tested, the chance of obtaining at least one apparently unusual result can increase. General statistical approaches can control that concern by specifying a testing hierarchy or adjustment in advance. The record does not report a multiplicity strategy, so the secondary p values should be read as unadjusted and not as family-wise adjusted evidence. Whether any adjustment was used outside the registry record is not reported.

Numerical secondary comparisons are posted for three refractive error outcomes. Numerical results for the other listed secondary outcomes are not reported in the registry record. The record also lists six outcome measures overall, but does not provide a complete set of numerical results in the details. The absence of a posted result should not be interpreted as a null finding.

Missing-data handling is not reported in the registry record. This matters because the primary entries list 9 observations for one lens and 7 for the other, despite an enrollment of 16 and a description indicating measurement in both lens conditions. The secondary entries list 16 observations for each lens. The record does not explain whether the primary counts reflect missing measurements, a particular analysis population, or another reason. No imputation approach, exclusion rule, or sensitivity analysis is reported.

The registry does not define analysis populations, such as which participants were included in each outcome summary, and it does not report how the crossover structure was handled. The identity of the masked party is also not reported. These are not grounds to assume that the conduct or analysis was inappropriate; they are limits on what can be evaluated from the registry record. A complete interpretation would require the analysis methods and participant-level accounting, which are not reported.

12. 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 figures list zero serious adverse events, zero other adverse events, and zero deaths in both lens groups. The serious adverse event figures are recorded among 9 participants at risk in the single vision group and 7 in the multifocal group. The other adverse event counts use the same group sizes. No serious adverse event terms are listed.

These are the registry's reported counts for the groups and should be read as such. They do not establish that no event occurred outside the recorded categories or reporting period, and they do not show whether investigators attributed events to a lens. The record does not provide further detail on adverse event definitions, collection methods, duration of safety observation, or causal assessment. The safety counts also do not answer the study's visual performance question. A zero count in a small study is a description of the posted observations, not proof that an event cannot occur.

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

The posted primary summaries show mean low contrast visual acuity values of 0.23 logMAR for the single vision lens entry and 0.38 logMAR for the multifocal lens entry. The registry does not report a primary contrast estimate or its uncertainty. Although lower logMAR values conventionally indicate better acuity, the means alone do not provide a complete inferential comparison, especially given the crossover design and the unexplained difference in primary observation counts.

The secondary results show a consistent direction in the three numerical comparisons: the posted mean differences, expressed as multifocal minus single vision, are negative. Their unadjusted intervals are below zero. This is a description of the posted comparisons, not a statement that one lens works or does not work. The registry does not show whether the calculations account for within-participant pairing, and it does not report adjustment for examining multiple secondary outcomes.

The findings do not establish the size or precision of a primary treatment contrast, because the necessary primary comparison and interval are absent. They also do not establish how the observed values might generalize beyond the participants studied. The registry record does not report detailed participant characteristics, a complete analysis plan, missing-data handling, or a sample-size justification.

More broadly, statistical evidence should be interpreted in relation to the design, measurement, analysis, and uncertainty. The posted means and secondary comparisons are informative summaries, but they are not a substitute for a fully reported crossover analysis. The sample-size illustrations are hypothetical planning aids based on observed secondary effects; they do not indicate observed power or validate the study's original design. These distinctions keep the conclusions aligned with what the registry actually reports.

14. Why This Trial Matters Statistically

This study is statistically interesting because its crossover design offers the possibility of comparing two lens conditions within the same participants. Such designs can be efficient when measurements are paired and the analysis reflects that pairing. They also require attention to sequence and period structure. The registry identifies randomized sequences but does not report how the analyses addressed those features.

The contrast between the primary and secondary reporting is also important. The primary endpoint has means and standard deviations but no inferential comparison, while the secondary results include mean differences, confidence intervals, and unadjusted p values. This means the apparent statistical detail is greater for secondary outcomes than for the primary question, even though the registry designates visual performance as primary. Readers should distinguish descriptive primary summaries from secondary calculations rather than treating every result as equally supported.

The different posted observation counts further illustrate why transparent participant accounting matters. The primary outcome entries list 9 and 7 observations, while the secondary outcomes list 16 for each lens. Without an explanation, readers cannot determine why these counts differ or how that affects the primary comparison. Clear reporting of paired data, exclusions, and analysis populations would help assess precision and potential bias.

Finally, unadjusted secondary results and observed-effect planning illustrations are easy to overinterpret. Multiple outcomes can make isolated statistical signals less persuasive, and planning calculations based on observed effects are not evidence of study power. The record's omissions do not invalidate the posted data, but they constrain the strength and scope of statistical conclusions that can be drawn from them.

15. 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.

Several limitations are specific to the information posted for this study. First, the primary visual performance result is only summarized by lens-specific means and standard deviations. The registry does not provide a primary mean difference, confidence interval, p value, or reported analysis. It is therefore not possible to assess the precision of the primary contrast from the registry results.

Second, primary observation counts differ between lens entries and do not match the count shown for the secondary results. The reason is not reported. Since the study is described as a crossover in which each participant wore both lenses, missing or unpaired primary measurements could affect interpretation, but the record does not say whether that is what occurred. No missing-data strategy or analysis population is reported.

Third, the record does not explain the statistical handling of the crossover. In particular, it does not say whether within-participant correlation, sequence, or period was incorporated in the secondary comparisons. The posted analyses are unadjusted, and the registry does not identify any multiplicity method despite listing several secondary outcomes. Numerical results for two listed secondary outcomes are not reported in the registry record.

Additional design and reporting details are absent, including who was masked, the sample-size justification, and further information about the testing and lens-wearing schedule. The registry does not report whether interim analyses or other analyses were conducted. These limitations concern what can be evaluated from the record; they should not be filled in by assumption. The posted results remain useful as summaries, but the omissions prevent a full assessment of the study's statistical plan and the robustness of its comparisons.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluating Contact Lens Optics — NCT05028790.
• Registry record last updated 2024-02-06; status last verified 2024-02.
• Results first posted 2024-02-06.
• 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.

19. Record Summary

NCT05028790, titled Evaluating Contact Lens Optics, is a completed randomized, single-masked crossover study in myopia. The registry reports enrollment of 16 and two lens-wearing sequences, with participants wearing both a single vision soft contact lens and a multifocal soft contact lens. The primary outcome is low contrast visual acuity in logMAR.

The primary results provide lens-specific means and standard deviations but no inferential comparison. Three secondary refractive error outcomes have posted mean differences, confidence intervals, and unadjusted p values. The record does not report a complete analysis plan, crossover-specific analysis details, multiplicity adjustment, missing-data handling, or the reason for different primary and secondary observation counts. Safety entries report zero serious adverse events, zero other adverse events, and zero deaths in the listed groups.