Clinical Evaluation of Two Multifocal Contact Lenses: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Evaluation of Two Multifocal Contact Lenses (NCT05457608), a non-randomized na study. The primary outcome is Subjective Comfort Ratings on Insertion.

2. Clinical Question

In practical terms, the study asks how participants rated their initial comfort with each lens. Its crossover structure means that the same participants experienced both lenses, rather than one group receiving only one lens and a separate group receiving the other. The posted sequence assigns Lens A to Period 1 and Lens B to Period 2 for all participants. Allocation is listed as non-randomized, so this is not a randomized comparison in which lens order is assigned at random.

The summary refers to subjective experiences after 15 minutes of daily wear, while the primary outcome description gives its timeframe as at insertion. These descriptions do not fully clarify when the comfort rating was collected relative to the wear period. That timing detail, along with the lens-type mapping, is not reported in the registry record. As a result, the question can be described, but the precise comparison and timing cannot be reconstructed beyond the information stated.

3. Trial Design

The registry record describes a completed, single-masked, non-randomized crossover study. Enrollment is listed as 42. All participants wore Lens A for 15 minutes in Period 1 and Lens B for 15 minutes in Period 2. The record therefore describes repeated exposure to both lenses, with the same order for all participants, rather than separate randomized groups receiving different lenses.

The study dates are listed as starting 2022-06-25 and reaching primary completion 2022-08-13. Its status is completed. The phase is recorded as NA. The sponsor is CooperVision, Inc. The registry title describes a clinical evaluation of two multifocal contact lenses, and the brief summary frames the objective as comparing subjective experience with monthly and daily disposable multifocal lenses. However, the registry's Lens A and Lens B labels are not linked to those lens types.

Single masking indicates that masking was recorded, but the identity of the masked party is not stated. The record also does not describe a washout period, how the periods were scheduled, or any steps to reduce the influence of lens order. Because every participant used A first and B second, lens identity and period are not separated by random order. A difference in ratings could therefore be influenced by the lens, the order of exposure, changes between periods, or other period-related factors; the registry record does not report an analysis addressing these possibilities.

The enrollment figure is a registry study-level count. It should not be interpreted as a reported count for a particular analysis, because the primary outcome population and analysis populations are not specified. The registry lists one outcome measure and zero analysis entries. A statistical plan, including the method used to compare the repeated observations, is not reported in the registry record.

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: Forty-two participants were screened. All participants wore Lens A first for 15 minutes and then wore Lens B for 15 minutes. All the participants who were in the study were included in the analysis. (n=42)

Period 1: Lens A (15 Minutes)

Period 2: Lens B (15 Minutes)

Analysis population for the primary outcome, as defined in the registry: \[Not Specified\]

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: Overall study

6. Primary Endpoint

The registry lists the primary outcome as Subjective Comfort Ratings on Insertion, measured over At insertion.

The primary endpoint is titled “Subjective Comfort Ratings on Insertion.” It is a continuous measure summarized as a mean, with standard deviation identified as the dispersion measure. Ratings use a scale from 0 - 10, where 0 means extremely uncomfortable and 10 means “can't feel.” Higher ratings therefore correspond to greater reported comfort on the stated scale.

A subjective rating is used to capture the participant's experience, which is the outcome of interest in a study focused on perceived lens comfort. A continuous scale can retain gradations in responses rather than reducing comfort to a yes-or-no category. The mean describes the average rating, while the standard deviation describes how spread out individual ratings are around that average. Neither alone establishes how precisely a comparison between lenses has been estimated; an uncertainty interval and a clearly specified contrast would also help readers assess precision.

The endpoint description gives its timeframe as “At insertion,” while the study summary refers to subjective experiences after 15 minutes of daily wear. The record does not explain whether the rating was recorded at insertion, after the wear period, or at both times. The population field for this endpoint is not specified in the registry record. Most importantly, no mean, standard deviation, or lens-to-lens contrast is reported, so the endpoint's observed values cannot be interpreted from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods matter because a summary measure, a comparison, and its uncertainty answer different questions. The registry identifies a continuous primary outcome summarized by a mean and standard deviation. It does not report the actual summaries or the analysis method. The explanations below describe general statistical concepts; they should not be read as a statement that any particular method was used in this study.

What does a mean describe?

For a continuous measure, the mean is the arithmetic average of the recorded ratings in the analysis population. It gives a central summary, but it does not show whether most ratings are close to that value or whether responses vary substantially. The standard deviation describes variation among observations around the mean. It is not an uncertainty interval for the mean or for a difference between lenses. Interpreting these quantities requires knowing which observations and participants were included, and the primary outcome population is not specified in the registry record.

Why does the crossover design matter?

In a crossover study, the same participant receives more than one condition, so measurements from that person may be correlated. A paired analysis accounts for that within-person relationship; an analysis that treats all measurements as independent may not. The appropriate approach depends on the actual data and design details. The registry record does not state whether the comparison used paired methods, a repeated-measures model, or another approach.

Here, the record states that all participants wore Lens A in Period 1 and Lens B in Period 2. Since lens and period change together in this fixed sequence, the observed contrast could reflect both lens and period-related influences. General methods for crossover studies may include period effects and, where relevant, carryover effects in an analysis. Whether such effects were assessed or addressed is not reported in the registry record. The record also does not describe any washout or other transition procedure.

How should uncertainty be read?

In general, a confidence interval represents uncertainty around an estimate under the assumptions of the statistical method. For a lens comparison, an interval around a mean difference would convey which contrast values are reasonably compatible with the data and model. A p-value addresses compatibility with a specified null hypothesis under statistical assumptions; it does not measure the size or clinical importance of a difference. Neither a confidence interval nor a p-value for the primary outcome is reported in the registry record. Without an estimate and its uncertainty, the data's precision cannot be assessed from this record.

Standard deviations describe the spread of individual ratings and can help readers understand how variable responses were. They do not, by themselves, quantify the precision of a paired lens comparison. That precision depends on the variability of within-participant differences, the number of observations included, and the analysis model. The registry record does not report the within-participant differences, their variability, or an analysis population. No recalculated comparison can be made from the recorded information.

What do planning assumptions mean?

General sample-size illustrations use assumptions about a target effect, significance level, allocation, and statistical approximation. The planning assumptions associated with this record specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; they also describe an effect defined as a stated fraction of the observed effect. These are planning assumptions, not evidence that the trial used those assumptions to select enrollment. The registry record does not report the protocol's sample-size justification or its design calculations.

Any sample-size result calculated from an observed effect is a planning illustration, not observed power and not a finding about the trial's success. Such an illustration asks what sample size might be needed under specified assumptions; it cannot replace an estimate and uncertainty interval for the actual outcome. Because primary outcome results are not reported in the registry record, no observed effect can be assessed from the posted results in this record. The registry does not describe an interim-analysis plan or a statistical analysis plan.

Why can variability affect analysis?

General statistical methods often assume a particular pattern of variability. If observations vary more than the model allows, uncertainty estimates and tests can be unreliable unless the model accounts for that extra variation. For a bounded rating scale, the distribution and concentration of ratings can also matter when choosing a model. These are general considerations rather than claims about this dataset: the individual ratings and their distribution are not reported in the registry record. Therefore, it is not possible to assess assumptions such as normality, influential observations, or whether an alternative model would be preferable.

Reproducible interpretation would require the analysis population, handling of repeated observations, treatment of missing values, outcome summaries, contrast definition, and uncertainty estimates. The registry record does not report these details. This absence limits evaluation of both the numerical result and the suitability of the method; it does not establish that a particular analysis was or was not performed outside the information recorded in the registry.

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("Lens A", "Lens B")
n   <- c(42, 42)
m   <- c(9.19, 9.47)
sp  <- c(0.86, 0.67)
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  Lens A  42  9.190  0.860  8.922  9.458
CARM  Lens B  42  9.470  0.670  9.261  9.679

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure, the subjective comfort rating on insertion. It lists zero analysis entries and does not describe a statistical analysis plan. The number of outcome measures recorded does not establish how many comparisons, time points, subgroups, or alternative analyses may have been considered. Whether any multiplicity adjustment was planned or used is not reported in the registry record.

Multiplicity is a general concern when many statistical tests or endpoints are examined: the chance of at least one apparently notable result can increase as the number of tests grows. Methods to address this depend on which comparisons were planned and which were considered primary. Since the analysis plan and reported analyses are absent, it is not possible to judge whether multiplicity was relevant to the reported work or how it was handled. No p-values for the primary outcome are reported.

Missing-data methods are also not described. The registry does not state whether any primary outcome ratings were missing, why they might be missing, or how missing observations were handled. It does not report an analysis population for the comfort endpoint; that endpoint's population is marked not specified. The enrollment entry alone does not establish the number of participants contributing outcome data or the completeness of the measurements.

In general, missing observations can affect a comparison if the availability of ratings is related to the participant's experience or differs across measurement conditions. Appropriate methods depend on the amount and pattern of missingness and the study's analysis plan. Those details and methods are not reported in the registry record. As a result, the robustness of any primary outcome analysis to missing data cannot be assessed from the record.

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 registry lists separate adverse-event entries for Lens A and Lens B. For each lens, 42 participants are recorded as at risk for serious events and 0 as affected; 42 are recorded as at risk for other events and 0 as affected. Deaths are recorded as 0 for each lens. These are the event figures in the registry record, not comfort ratings.

In a crossover study, the same participants may contribute exposure to both lenses. The at-risk figures for the two lens entries therefore should not be added to infer a number of unique participants. The record describes the exposure sequence as Lens A in Period 1 and Lens B in Period 2. It does not provide further detail on adverse-event observation periods, event definitions, ascertainment, or whether events were attributed to a particular lens.

Zero recorded affected participants means that the registry lists no affected participants in those adverse-event categories for these entries. It does not, by itself, establish that no events could occur outside the recorded observation or that the risk is zero. The registry record does not report confidence intervals or other uncertainty estimates for these safety figures. These entries also do not fill the gap in the primary comfort results, which are not reported.

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

The registry describes a clinical evaluation of two multifocal contact lenses and identifies subjective comfort on insertion as the primary outcome. Its scale runs from 0 - 10, with higher values representing greater comfort according to the stated anchors. The study uses a crossover sequence in which all participants wore Lens A in Period 1 and Lens B in Period 2. These details explain what the evaluation was intended to examine, but they are not a report of its primary outcome findings.

No mean comfort ratings, standard deviations, estimated difference, confidence interval, or p-value are reported in the registry record. Thus, the posted results recorded do not establish the direction, magnitude, or precision of a comfort contrast. Missing numerical results should not be interpreted as evidence that the lenses produced the same ratings or that either lens had an advantage. The registry record simply does not report the outcome data needed to answer those questions.

The study summary frames the comparison as monthly versus daily disposable multifocal lenses, but it does not map those lens types to Lens A and Lens B. The outcome description specifies a rating at insertion, while the summary describes subjective experiences after 15 minutes of daily wear. This leaves the exact lens identification and rating timing unclear in the record. Interpretation of any comparison would depend on those details as well as the analysis method and population.

The fixed sequence and non-randomized allocation also constrain interpretation. Because each participant used Lens A first and Lens B second, an observed contrast could be entangled with period or order effects. The record does not state whether these factors were addressed analytically. The reported zero adverse-event counts are limited to their registry entries and do not provide evidence about comparative comfort or resolve these design considerations.

Accordingly, the information recorded is useful for understanding the study's objective, outcome definition, exposure order, and listed safety counts. It is insufficient for a statistical conclusion about the primary endpoint. Any stronger statement about relative comfort, precision, or clinical importance would require outcome results and analysis details that are not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates why design details and results must be read together. A crossover design exposes participants to both lenses, so the comparison can use information from within the same person. That feature makes the relationship between repeated ratings important: statistical methods should reflect whether ratings from one participant are related. The registry record does not state which method was used, so readers cannot verify how that structure was handled.

The fixed order is also consequential. Every participant received Lens A in Period 1 and Lens B in Period 2, and allocation is described as non-randomized. The lens comparison therefore coincides with the period comparison. Randomized ordering can help distinguish treatment effects from order effects in crossover studies; this record does not describe randomized ordering. The design does not make a lens contrast automatically invalid, but it does make period-related influences important to consider.

The outcome itself is a subjective rating, an appropriate kind of measure for a question about perceived comfort. Yet its timing is not fully clear: the outcome description says at insertion, and the summary refers to experience after 15 minutes of daily wear. Clear timing is important because an initial sensation and an experience after a wear period are not necessarily the same measurement occasion.

Finally, a well-defined measure cannot substitute for its results. The mean and standard deviation are identified as the intended summary, but the registry record reports neither. Without an estimate and uncertainty measure, readers cannot judge how large or precise a difference may be. This case underscores the value of complete outcome reporting, explicit analysis methods, and clear mapping between coded intervention labels and the treatments they represent.

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 follow from the registry record itself. First, no primary outcome values or analysis results are reported. The mean ratings, standard deviations, comparison estimate, uncertainty interval, and p-value are absent. This prevents assessment of the size, direction, and precision of the stated comfort outcome.

Second, the outcome population is not specified. Although enrollment is listed as 42, the record does not identify the participants included in the primary endpoint analysis or whether all enrolled participants contributed usable ratings. Missing-data handling and the analysis population are not reported.

Third, the intervention labels are not linked to the lens types named in the study summary. The record describes monthly and daily disposable multifocal lenses as the comparison of interest, but it does not say which is Lens A or Lens B. The timing description is also not fully aligned: the endpoint is specified as at insertion, while the summary refers to experience after 15 minutes of daily wear.

Fourth, the non-randomized fixed sequence means that lens and period are paired in the same order for all participants. The record does not describe a washout, period-effect assessment, or analysis method for repeated observations. It also does not identify who was masked, despite listing the study as single-masked.

Finally, the registry record does not report a statistical analysis plan, sample-size justification, multiplicity strategy, or interim-analysis plan. These omissions limit evaluation of the intended and performed analyses. The listed adverse-event counts do not address these limitations or substitute for the missing comfort results.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Clinical Evaluation of Two Multifocal Contact Lenses — NCT05457608.
• Registry record last updated 2023-12-20; status last verified 2022-09.
• Results first posted 2023-09-21.
• 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

NCT05457608 is a completed, single-masked, non-randomized crossover study listed under presbyopia. Enrollment is 42. All participants wore Lens A for 15 minutes in Period 1 and Lens B for 15 minutes in Period 2. The summary describes a comparison of monthly and daily disposable multifocal lenses, but the record does not map those lens types to the A and B labels.

The primary measure is subjective comfort on insertion, summarized as a mean and standard deviation on a scale from 0 - 10. Its population is not specified. The registry lists one outcome measure and zero analysis entries, but reports no primary outcome values or comparative analysis. Adverse-event entries list 0 serious events affected, 0 other events affected, and 0 deaths for each lens group. The record does not report the analysis plan, missing-data handling, or timing details that would clarify the difference between the insertion endpoint and the summary's 15-minute description.