Clinical Comparison of Two Soft Contact Lenses: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Comparison of Two Soft Contact Lenses (NCT06251154), a non-randomized na study. The primary outcome is Subjective Overall Score.

2. Clinical Question

3. Trial Design

The registry record describes a completed clinical comparison of two soft contact lenses, sponsored by CooperVision, Inc. It lists myopia as the condition, an enrollment of 50, and a crossover model. The study is titled “Clinical Comparison of Two Soft Contact Lenses”; its official title identifies it as an iteration under umbrella protocol C19-678. The phase is listed as NA.

All participants wore Lens 1 for 15 minutes in Period 1 and Lens 2 for 15 minutes in Period 2. Thus, the record describes a common, fixed order rather than randomized allocation to different sequences. The allocation is explicitly listed as nonrandomized. Although masking is listed as single, the record does not say who was masked or how masking was maintained.

The crossover structure means each participant was scheduled to experience both lenses, which can make within-participant comparisons relevant when analysis is designed to account for repeated measurements. However, a fixed sequence means lens identity is linked to period: Lens 1 is always used first and Lens 2 second. Period effects, changes over time, or effects carried from the first wear period could therefore complicate interpretation of a lens contrast. The registry record does not report a washout interval, random sequence assignment, or an analysis that accounts for period or carryover.

The study status is completed. The listed start date is 2023-12-11 and the primary completion date is 2024-01-08. These dates describe the registry record; they do not supply outcome results. The record lists three outcome measures, but no analyses are listed. Results for the primary endpoint are 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.

Period 1: Lens 1, 15 Minutes

Period 2: Lens 2, 15 Minutes

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 Overall Score, measured over 15 minutes.

The primary endpoint is the subjective overall score, recorded after 15 minutes. It is a mean on a 0-100 visual analogue scale. The record defines 0 as “Extremely poor, unmanageable, cannot use lenses” and 100 as “Excellent, highly impressed with these lenses overall.” The scale is intended to capture a participant’s overall subjective impression rather than an objective measure of lens performance.

A continuous score can retain gradations in participants’ ratings, rather than reducing experience to a simple yes-or-no category. Reporting a mean describes the average rating in the analyzed group, while a standard deviation describes how spread out individual scores are around that mean. Those summaries would help readers understand both the group-level rating and variation in participants’ responses.

The endpoint is relevant to a short-term comparison because it asks about the overall impression after a defined wear period. It does not, by itself, describe longer-term comfort, vision, sustained use, or other outcomes. The registry also lists subjective comfort and subjective vision as secondary outcomes, but their detailed measurement procedures and results are not reported in the registry record.

Although the endpoint definition and scale anchors are stated, the observed mean and standard deviation for either lens, along with any estimated contrast and uncertainty interval, are not reported in the registry record. The endpoint’s meaning can therefore be described, but the posted record does not show the actual ratings or establish how the lenses compared.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is continuous, and the registry specifies a mean with standard deviation as its summary. That choice describes the average subjective rating and the spread of scores around that average. The record does not report the actual summaries or identify a statistical test used to compare the lenses.

What does a mean and standard deviation describe?

A mean gives a central summary of the recorded scores. It is useful for expressing the average rating on the stated scale, but it does not show whether participants’ responses were tightly clustered or widely dispersed. The standard deviation gives information about that dispersion. Neither quantity alone shows the uncertainty in a comparison estimate. A confidence interval around a contrast addresses uncertainty in the estimated difference, while the standard deviation describes variability among observations. These are related but distinct ideas.

For this study, the registry names the endpoint as a mean and the dispersion measure as a standard deviation. It does not report either lens’s observed mean or standard deviation. It also does not report an estimated contrast or a confidence interval. Accordingly, the statistical summaries that would be needed to judge the magnitude and precision of the comparison are unavailable in the registry record.

Why does the crossover structure matter?

In a crossover study, participants receive more than one condition, so measurements from the same participant are related rather than independent. A suitable analysis may account for that within-participant relationship. Treating repeated observations as if they came from unrelated people can misrepresent uncertainty because it ignores the connection between a participant’s responses under the different conditions.

Here, all participants wore Lens 1 first and Lens 2 second. This fixed sequence links the lens comparison to the period of use. If ratings change over time, or if experience with the first lens affects the later rating, a simple difference between lens-period summaries may combine lens and order influences. Randomized sequence assignment can help separate those influences, but the record lists nonrandomized allocation and does not describe different sequences. The statistical model, handling of period effects, and handling of possible carryover are not reported in the registry record.

How should uncertainty and significance be read?

In general, a confidence interval expresses a range of values compatible with an estimated effect under the statistical model and its assumptions. It can help readers assess both the direction and precision of an estimate. A p-value addresses how compatible the observed data are with a specified null hypothesis under the test assumptions; it does not measure the size or importance of an effect. These general interpretations do not substitute for study-specific results. No confidence interval or p-value for the primary outcome is reported in the registry record.

The registry record also does not state whether the primary analysis was adjusted, which test or model was used, or which assumptions were checked. For continuous outcomes, methods may rely on distributional and model assumptions. The particular method and its adequacy cannot be assessed without a reported analysis plan and results.

What do the planning assumptions mean?

The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It defines the effect to detect as a stated fraction of the observed effect. Such an illustration is a planning calculation, not evidence that the study had a particular probability of detecting an effect. It is not observed power. The registry record does not report the underlying observed effect or a resulting sample-size illustration in the study results.

The record notes that non-time-to-event planning illustrations are expressed as participants per arm, while time-to-event illustrations use a total number of events. This study’s primary measure is a continuous score, not a time-to-event endpoint. No study-specific planning result is reported in the registry record. The record also does not report the original sample-size justification, so the planning description should not be mistaken for the trial’s own design rationale.

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 1", "Lens 2")
n   <- c(50, 50)
m   <- c(80.2, 88.2)
sp  <- c(16.7, 11)
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 1  50  80.200  16.700  75.454  84.946
CARM  Lens 2  50  88.200  11.000  85.074  91.326

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists the subjective overall score as the primary outcome and lists subjective comfort and subjective vision as secondary outcomes. It also reports three outcome measures. Considering more than one outcome can raise a multiplicity issue: when several hypotheses are tested, the chance of at least one apparently notable result can increase if each is assessed without adjustment. Statistical approaches can address multiplicity, but the appropriate approach depends on the prespecified questions and analysis plan.

The registry record does not report whether multiplicity was addressed, whether secondary outcomes were treated as exploratory, or whether any hierarchy of testing was prespecified. It also does not provide outcome-specific results or analyses. Therefore, no conclusion can be drawn about the handling or consequences of multiple comparisons in this study.

Missing-data methods are also not reported in the registry record. It does not state whether any outcome observations were missing, how missing observations were handled, or whether sensitivity analyses were conducted. The planned wear periods and enrollment figure do not establish that complete endpoint data were available for every participant.

The analysis population is not defined in the registry record. It does not say whether analyses included all enrolled participants, only those completing both periods, or another set of participants. Nor does it report exclusions, protocol deviations, or how participants with incomplete crossover observations would be treated. These details matter because the analyzed group and missing-data assumptions can affect the estimate and its interpretation.

Without multiplicity procedures, missing-data reporting, and a defined analysis population, the reader cannot assess these aspects of the statistical analysis. Their absence from the registry record is a reporting limitation, not evidence that a particular procedure was or was not used outside the posted 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 5% reporting threshold.

The registry safety figures list Lens 1 and Lens 2 separately. For each lens, the record reports 50 at risk for serious adverse events and zero affected; it also reports 50 at risk for other adverse events and zero affected. Deaths are reported as zero for each lens. No serious adverse event terms are listed.

These are the posted counts, not a comparison demonstrating that the lenses have identical safety profiles. The study is a crossover in which all participants wore both lenses, so the two lens listings should not be treated as independent groups or added to describe the number of distinct participants. The record does not explain the event-collection procedures, duration of safety follow-up beyond the stated wear periods, or whether any event definitions or adjudication procedures were used.

Zero reported events means no affected participants are listed in these registry safety figures. It does not establish that the underlying risk is zero, particularly when the exposure and follow-up described are short. The figures should be read as the safety data posted in the registry record, with the study’s design and limited reported detail in mind.

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

The registry record establishes that a completed short-term comparison was conducted in which participants wore Lens 1 and Lens 2 in a fixed order. It defines a subjective overall score on a 0-100 visual analogue scale and identifies subjective comfort and subjective vision as secondary outcomes. It also reports safety counts for the two lens periods.

Those details describe the study question and its structure, but they do not answer the primary comparative question. The primary score results are not reported in the registry record, and no analyses are listed. There is therefore no posted estimate showing the difference between lens ratings, no uncertainty interval indicating its precision, and no p-value to interpret. The record cannot support a statement that one lens had a higher or lower overall score.

Even if outcome values were available, the fixed order would remain important. Because Lens 1 was always worn in Period 1 and Lens 2 in Period 2, a contrast could reflect lens-related differences, period-related changes, or effects of the earlier wear period. Nonrandomized allocation further limits a causal interpretation. The registry record does not report an analysis addressing these issues.

The endpoint concerns subjective overall impressions after 15 minutes. It does not directly establish longer-term performance, continued use, or outcomes beyond those measured. The listed secondary outcomes do not have reported results in the registry record. Similarly, the zero counts in the posted adverse-event figures describe the registry entries; they do not prove an absence of risk.

The appropriate reading is therefore limited: the record documents a short-term, fixed-sequence crossover comparison and defines what participants were asked to rate. It does not provide the outcome results needed to judge the comparative scores, their precision, or their practical meaning.

14. Why This Trial Matters Statistically

This study illustrates why design details are essential when interpreting a clinical comparison. The crossover model means each participant was scheduled to experience both lenses, making within-participant information potentially relevant. At the same time, the fixed order links each lens to a different period. Without random sequence allocation or a reported method for addressing period and carryover effects, a contrast cannot be interpreted as a clean separation of lens and order influences.

It also illustrates the distinction between an endpoint definition and an endpoint result. The record describes a 0-100 subjective scale with explicit anchors and names the summary as a mean with standard deviation. Those details clarify what the planned measure represents. They cannot replace the observed scores, variability, comparison estimate, and uncertainty interval needed to assess the findings. The primary results and analyses are not reported in the registry record.

The safety entries offer another useful lesson in restraint. Zero affected participants are listed for serious and other adverse events, and deaths are listed as zero, for both lenses. Because the same participants wore both lenses and the reported wear periods were short, these counts should not be converted into a claim of equal safety or zero risk.

Finally, the record describes a planning illustration based on an observed effect. Planning calculations are not observed power and do not supply missing clinical results. This distinction helps keep planning assumptions separate from what the study actually measured and reported. Overall, the record shows how allocation, sequence, endpoint reporting, and uncertainty all shape what can responsibly be inferred from a clinical trial entry.

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.

The principal limitation for interpreting this comparison is that the primary endpoint results are not reported in the registry record. The record gives no observed means or standard deviations, estimated lens contrast, confidence interval, or p-value. It lists no analyses, so the statistical method and the precision of any comparison cannot be evaluated.

The design is nonrandomized and uses a common sequence: all participants wore Lens 1 in Period 1 and Lens 2 in Period 2. Lens and period are therefore linked. The registry record does not report a washout interval, alternative sequences, or an analysis accounting for period or carryover effects. The listed single masking does not identify who was masked or how.

The record provides limited information about participants beyond myopia and enrollment. It does not report participant characteristics, the analysis population, missing outcome data, exclusions, or missing-data methods. Although the primary and secondary outcomes are named, detailed measurement procedures for the secondary outcomes and their results are not reported. The approach to multiplicity is also not reported.

The short wear periods limit the scope of the described endpoint: the primary score was assessed after 15 minutes. The record does not establish longer-term experience or performance. Safety reporting lists zero affected participants in the stated categories, but event definitions and collection procedures are not described in the record. These reporting and design limitations mean that the posted information supports description of the study setup, not a definitive comparative conclusion.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Clinical Comparison of Two Soft Contact Lenses — NCT06251154.
• Registry record last updated 2024-08-22; status last verified 2024-01.
• Results first posted 2024-04-16.
• 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

NCT06251154 is a completed, nonrandomized crossover study titled “Clinical Comparison of Two Soft Contact Lenses.” The registry lists myopia, an enrollment of 50, single masking, and CooperVision, Inc. as sponsor. The listed start date is 2023-12-11 and the primary completion date is 2024-01-08.

All participants wore Lens 1 for 15 minutes in Period 1 and Lens 2 for 15 minutes in Period 2. The primary outcome was a subjective overall score on a 0-100 scale, summarized as a mean with standard deviation. Subjective comfort and subjective vision were listed as secondary outcomes.

The registry record does not report the primary outcome values or analyses. Its safety figures list zero serious adverse events, zero other adverse events, and zero deaths for each lens. The fixed sequence and nonrandomized allocation should be considered when interpreting any comparison.