This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Dispensing Clinical Trial of a Study Test Silicone Hydrogel Lens Against Control Lens Over 1 Week (NCT02500368), a randomized na study. The primary outcome is Comfort.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02500368 |
| Phase | NA |
| Condition | Myopia |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Double |
| Enrollment | 41 |
| Arms in the primary outcome | n/a |
| Lead sponsor | CooperVision, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns participants with myopia. The registry reports enrollment of 41, but does not describe the participants’ ages, baseline comfort, eligibility details, or the number included in each outcome analysis. The number enrolled should not be treated as the number contributing data to every endpoint.
Intervention
The test intervention was a silicone hydrogel lens. Participants were randomized to wear the test lens for 1 week during the crossover study. The registry does not report additional fitting, handling, or lens-use instructions.
Comparator
The control was an enfilcon A lens, also worn for 1 week during the crossover study. The registry does not provide the order in which each participant received the lenses, or whether any period between lens use was used.
Primary question
The primary outcome is comfort, recorded as a subjective rating on a 0-100 scale at baseline and at 1 week. The registry lists ratings at lens dispense at baseline, lens insertion at 1 week, and overall at 1 week. It does not report a single numerical comparison between the test and control lenses, so the relative comfort result cannot be determined from this record.
In plain terms, the study asks how participants rated comfort while using the test lens compared with the control lens under the trial’s crossover arrangement. Randomization concerns assignment to the study’s lens-use arrangements; it does not by itself show that the lenses produced different ratings. The crossover format means that lens comparisons may use information from participants across more than one lens period, but the exact sequence and analysis are not described in the registry record.
The stated study duration was 1 week, and the brief summary calls it a 1-week dispensing, double-masked, randomized, bilateral study. “Bilateral” is the registry’s description; further details about how outcomes were recorded for each eye are not reported in the registry record. Without the numerical comfort results and a defined comparison, the study question can be identified, but its answer cannot be quantified from the posted record.
3. Trial Design
The registry describes a randomized, double-masked, bilateral crossover study of a test silicone hydrogel lens and an enfilcon A control lens. The study was listed as completed, with enrollment of 41. The recorded start was 2015-07 and primary completion was 2015-08. The condition listed is myopia, and the sponsor is CooperVision, Inc. The phase is listed as NA.
In general, randomization is a process for assigning participants to study arrangements by chance. It can reduce systematic differences between assigned groups, although it does not guarantee that groups are identical. The registry does not describe the randomization method, allocation concealment, or the specific randomized sequences. It states that the study was double-masked, but does not identify which people were masked or explain how masking was maintained.
In general, a crossover design evaluates more than one intervention within a participant over successive study periods. It can allow comparisons that account for stable differences between participants. Interpretation can also depend on sequence, period effects, and whether an earlier intervention affects observations in a later period. Those are general considerations, not evidence that such effects occurred in this trial. The sequence, period details, washout arrangements, and any assessment of carryover are not reported in the registry record.
The arm descriptions say that participants were randomized to wear the test lens for 1 week or the control lens for 1 week during the crossover study. These descriptions do not establish the total number of lens periods, the precise order for each participant, or how many participants completed each period. Those details are not reported in the registry record. The registry’s bilateral description also does not specify whether analysis was conducted by participant, eye, or another unit.
Although enrollment was 41, the adverse-event entries list 40 participants at risk in each lens group. These entries should be read as group-specific safety counts, not as a complete account of outcome-analysis populations or crossover sequences. The number contributing to the primary comfort analysis is not reported in the registry record. A sample-size justification and the protocol’s analysis plan are also 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: One participant discontinued from the study as a screen failure before lens randomization.
First Intervention (1 Week)
| Stage | Silicone Hydrogel Lens (Test), Then Enfilcon A Lens (Control) | Enfilcon A Lens (Control), Then Silicone Hydrogel Lens (Test) |
|---|---|---|
| STARTED | 20 | 20 |
| COMPLETED | 20 | 20 |
| NOT COMPLETED | 0 | 0 |
Second Intervention (1 Week)
| Stage | Silicone Hydrogel Lens (Test), Then Enfilcon A Lens (Control) | Enfilcon A Lens (Control), Then Silicone Hydrogel Lens (Test) |
|---|---|---|
| STARTED | 20 | 20 |
| COMPLETED | 20 | 20 |
| NOT COMPLETED | 0 | 0 |
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.
| Characteristic | Unit | Overall Baseline Characteristics |
|---|---|---|
| Participants analysed | 41 | |
| Age, Continuous | years | 24 (19 to 55) |
| Sex: Female, Male: Female | Participants | 28 |
| Sex: Female, Male: Male | Participants | 13 |
6. Primary Endpoint
The registry lists the primary outcome as Comfort, measured over Baseline and 1 week.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | units on a scale |
| Endpoint classification | Continuous Endpoint |
The primary outcome is comfort, measured as units on a scale and summarized in the registry as a mean with standard deviation. The scale runs from 0 to 100. Its anchors describe a progression from “Cannot be worn, causes pain” at 0, through ratings of irritation and noticeability, to “Cannot be felt ever” at 100. These labels give the rating a practical interpretation: higher scores correspond to descriptions of less noticeable or more comfortable lens wear.
The registry lists three comfort assessment points: lens dispense at baseline, lens insertion at 1 week, and overall at 1 week. The primary outcome timeframe is described as baseline and 1 week. These are not necessarily interchangeable measurements: an assessment at insertion can capture an immediate impression, whereas an overall assessment can reflect a broader judgment of the period. The registry does not further define the recall period or explain how the assessments were combined, if at all.
Comfort is a subjective outcome, so it records the participant’s reported experience rather than an objective physical measurement. In general, such ratings can be useful when the question concerns how an intervention feels to the person using it. The scale’s verbal anchors help readers understand what the endpoints mean, but they do not establish that every step between scores represents an equal change in experience.
The registry does not report numerical means, standard deviations, a treatment contrast, or uncertainty estimates for comfort. It also indicates that the primary outcome has several categories or time points and was not reduced to one comparison. Therefore, the endpoint’s intended meaning is clear, but the posted record does not provide a single test-versus-control comfort estimate to interpret.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies comfort as the primary outcome and describes how it was rated, but it does not report numerical results for that outcome. No mean ratings, standard deviations, test-versus-control estimate, confidence interval, or p-value are included in the record. The posted information therefore does not establish the direction or size of any difference in comfort between the lenses, nor how precisely such a difference was estimated.
The record notes that the primary outcome includes several categories or time points and was not reduced to one comparison. This matters because a baseline rating, an insertion rating, and an overall rating at 1 week describe distinct measurements. A reader should not treat one assessment as a substitute for another or infer a preferred time point. The registry does not state which comparison was intended to be primary among these assessments, or how results across them would be handled.
In general, a mean describes the average of observations, while a standard deviation describes how dispersed individual observations are around that mean. A difference between means would summarize the contrast in average ratings, but its interpretation would depend on the scale, the analysis population, and the study design. A confidence interval would express the uncertainty around an estimated contrast. These are general statistical explanations; no such comfort estimates or intervals are reported in the registry record.
The crossover structure is relevant to interpretation. In general, a crossover comparison may use repeated observations within participants, so an analysis should account for the relationship between measurements from the same participant and for the periods in which interventions were received. An analysis that ignores the design may not represent the intended comparison. The registry does not report the statistical model, the sequence-specific results, period effects, or how within-participant correlation was handled. No analysis result is posted from which to assess those choices.
The study enrolled 41 participants. Enrollment alone does not show how many participants contributed data to each comfort assessment, whether any observations were missing, or whether the analysis included all enrolled participants. Those details are not reported in the registry record. The absence of a reported estimate also means that precision cannot be judged: the record does not show whether any potential contrast was narrow or uncertain.
The record lists 22 outcome measures and 0 analyses. It also lists secondary outcomes including lens wettability, surface appearance, high-contrast acuity at high room illumination, lens deposition, lens problems, and lens centration. The registry’s outcome descriptions do not supply numerical results for those outcomes in the registry record for this account. Their listing should not be interpreted as evidence of a difference or no difference.
Safety entries report 0 serious adverse events and 0 other adverse events affecting participants in each lens group, with 40 participants at risk in each group. These are the recorded counts and do not answer the comfort question. Death counts are not reported in the registry record. Overall, the posted record defines the study and its outcomes but does not supply efficacy estimates or enough analysis detail to draw a statistical conclusion about the comparative comfort ratings.
9. Statistical Methods Explained
Understanding a trial result requires more than knowing its outcome measure. The study design, the analysis population, the estimate, and its uncertainty all affect what a comparison means. In this registry record, the design and comfort scale are described, but numerical comfort results and details of the analysis are not reported. The explanations below are general statistical guidance, not claims about methods used in this trial.
What does randomization contribute?
In general, randomization assigns participants to study arrangements by chance. Its purpose is to limit systematic differences in participant characteristics that might otherwise influence a comparison. It does not guarantee balance in every characteristic, especially in a study with limited enrollment, and it does not correct problems that arise after assignment, such as missing outcome data or departures from the planned procedure. The registry describes the trial as randomized but does not report the randomization sequence method or allocation concealment.
How does a crossover design affect analysis?
In general, a crossover design observes participants under more than one intervention across study periods. Because measurements from the same person are often related, a statistical comparison commonly needs to account for that within-participant relationship. The order of interventions and the period of measurement may also matter. If an earlier period affects a later one, that may complicate interpretation. These are general design considerations; the registry does not report the lens sequences, period-specific data, washout details, carryover assessment, or analysis approach for this trial.
The registry calls the trial bilateral. That description indicates the study involved both eyes, but the analysis unit is not identified in the record. In general, measurements from two eyes of one participant may be correlated. Treating them as independent observations can understate uncertainty if their relationship is ignored. Whether the trial analyzed participant-level ratings, eye-level observations, or another summary is not reported in the registry record.
What do the mean and standard deviation describe?
The primary outcome is a continuous measure summarized by a mean and standard deviation. In general, the mean is an average that can describe the central level of ratings, while the standard deviation describes how much individual ratings vary around that average. Neither quantity alone gives the test-versus-control contrast. To interpret a comparison, readers would also need a clearly defined contrast and an account of uncertainty. The registry does not report comfort means, standard deviations, or a contrast.
The scale ranges from 0 to 100, with verbal descriptions at selected points. In general, a numeric rating scale enables observations to be summarized and compared, but the scale’s numbers do not automatically guarantee equal experiential distances between all possible scores. The verbal anchors help clarify what low and high ratings signify. The precise interpretation of an average should still be connected to the underlying scale and assessment time point.
Why do uncertainty estimates matter?
In general, a confidence interval gives a range of values compatible with the data under the assumptions of the analysis. It communicates precision, not the probability that a particular treatment effect is true. A narrow interval indicates a more precise estimate than a wide interval, while either can include values with different practical interpretations. No confidence interval for comfort is reported in the registry record.
A p-value, in general, assesses how unusual data at least as incompatible with a specified null hypothesis would be under the model assumptions. It does not measure the size or importance of a difference, and it does not establish that a null hypothesis is true when a result is not statistically significant. No p-value for the primary comfort comparison is reported. Without an estimate and its uncertainty, the record does not allow readers to assess either the magnitude or precision of a contrast.
How should the planning assumptions be understood?
The registry describes a planning illustration 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, a sample-size calculation asks how many observations might be needed under specified assumptions to detect a chosen effect with a chosen probability, subject to the calculation’s model. Such a calculation is not a result observed in the trial and is not observed power. It cannot substitute for the actual estimate and its uncertainty.
The record does not report the trial’s own sample-size justification, and the available record does not include numerical planning results or a numerical observed comfort effect. The stated planning framework should therefore be read only as an illustration of assumptions, not as evidence that the study was designed around a particular comfort difference. A planned sample size and an achieved enrollment are distinct quantities; the record reports enrollment of 41.
Why are multiple outcomes and time points important?
In general, evaluating many outcomes or time points can increase the chance that at least one result appears notable by chance if each is assessed separately. Statistical approaches to multiplicity may adjust thresholds, define a hierarchy, or otherwise control how conclusions are made across comparisons. The appropriate approach depends on the prespecified analysis plan. The registry lists 22 outcome measures and notes several categories or time points for the primary outcome, but it does not report a multiplicity strategy or a single primary comparison.
The record reports 0 analyses. Consequently, there are no posted analysis details from which to evaluate model assumptions, handling of repeated measurements, missing-data methods, or adjustment for multiple comparisons. These omissions do not show that a particular method was or was not used in the study; the methods are simply not reported in the registry record. Statistical interpretation should remain limited to the design and outcome definitions that are recorded, without inventing an estimate or an analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 22 outcome measures, including a primary comfort outcome with several categories or time points. It explicitly indicates that the primary outcome was not reduced to one comparison. The record reports 0 analyses, so it does not provide an analysis set of results from which to determine how the different comfort assessments or secondary outcomes were evaluated.
In general, examining multiple outcomes and time points can make chance findings more likely if each is interpreted as a separate test. A prespecified hierarchy, adjustment, or other multiplicity strategy can clarify how evidence across comparisons is handled. The registry record does not report a multiplicity plan, a primary contrast among the comfort assessments, or which secondary outcomes were intended to support formal inference.
The analysis population for comfort is not reported in the registry record. The record does not state how many participants contributed to each assessment, how missing ratings were handled, whether participants were analyzed according to randomized sequence, or whether any participants were excluded from an analysis. Imputation, sensitivity analyses, and rules for incomplete crossover data are not reported in the registry record.
These omissions do not establish that data were missing, that exclusions occurred, or that no multiplicity approach was used. They mean the posted record does not describe those decisions. As a result, the reader cannot assess whether results across endpoints were adjusted for multiple testing or whether the outcome analysis included all participants and observations relevant to the design.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Silicone Hydrogel Lens (Test) | 0 | 40 | 0.0% |
| Enfilcon A Lens (Control) | 0 | 40 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Silicone Hydrogel Lens (Test) | 0 of 40 |
| Enfilcon A Lens (Control) | 0 of 40 |
The safety entries report 40 participants at risk in the silicone hydrogel test lens group and 40 at risk in the enfilcon A control lens group. In each group, 0 participants are listed as affected by serious adverse events and 0 as affected by other adverse events. The entries therefore describe zero affected participants in the recorded categories for each group.
These figures should be read as counts in the registry’s safety fields, not as a complete description of every possible safety outcome. They do not provide event-level descriptions, timing, severity details beyond the serious-versus-other grouping, or a statistical comparison between lenses. The registry does not report the method used to collect or classify adverse events.
Death counts are not reported in the registry record. The entries also do not establish whether every enrolled participant contributed to safety follow-up or how exposure was defined across the crossover periods. Although 40 participants are listed at risk in each group, that information does not identify the number of distinct participants completing each period. The safety figures should not be used to infer comparative risk beyond the counts recorded.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, double-masked, bilateral crossover study compared a silicone hydrogel test lens with an enfilcon A control lens over 1 week. It defines comfort as the primary outcome and describes a subjective 0-100 rating scale, with assessments at baseline and at 1 week. It also lists secondary outcomes concerning lens properties, visual acuity, lens problems, and centration.
What the record does not establish is the numerical comfort result. No means, standard deviations, comparison estimate, confidence interval, or p-value are reported. The primary outcome was not reduced to one comparison, and the registry lists 0 analyses. Therefore, the record cannot show the size, direction, or precision of any test-versus-control contrast. It cannot establish that either lens had higher or lower comfort ratings.
In general, a study design describes how evidence was intended to be collected; it does not itself demonstrate an outcome. Randomization and masking are design features, while conclusions about the measured ratings depend on the results and the analysis. The crossover structure also makes the sequence, periods, and within-participant analysis relevant details, none of which are reported in sufficient detail to assess the comparison.
The safety record lists 0 serious adverse events and 0 other adverse events affecting participants in each lens group, with 40 at risk in each group. These counts are descriptive and do not supply a formal comparative safety analysis. Death counts are not reported in the registry record.
The appropriate reading is therefore limited: the registry defines a clinical question and records basic design and safety information, but it does not provide a statistical answer to the primary comfort question. The absence of reported results is not evidence that the lenses were equivalent, nor is it evidence that they differed. A conclusion about the observed comfort contrast would require results and analysis details that are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial is statistically interesting because its crossover design raises questions about how repeated observations should be compared. In general, a crossover study can make within-participant contrasts informative, since each participant may contribute experience under more than one intervention. That benefit depends on knowing the intervention sequence, study periods, and analysis method. The registry identifies the crossover model but does not report those details, so readers cannot evaluate how the design was incorporated into the analysis.
The comfort endpoint also illustrates why outcome definitions matter. Its 0-100 scale has verbal anchors that connect numerical ratings with descriptions of wear experience. Yet the registry lists assessments at baseline, lens insertion at 1 week, and overall at 1 week. Those assessments can address different aspects of comfort. A clearly specified primary comparison is important for interpreting results, especially when a single outcome includes multiple assessment times. The record states that the endpoint was not reduced to one comparison.
More broadly, the record distinguishes trial registration from a complete statistical results report. It documents randomized, double-masked, bilateral study features and enrollment of 41, but lists 0 analyses. Without estimates and uncertainty measures, readers cannot judge effect size, precision, or whether the statistical model reflects the crossover design. This is a useful reminder that outcome names and design labels alone do not answer a comparative question.
The record’s safety entries also show the value of distinguishing event counts from comparative inference. Each group has 40 participants at risk and 0 affected participants in the serious and other adverse-event categories. Those counts are informative as recorded, but they do not by themselves establish that risks are the same or different. Overall, the trial matters statistically as an example of how outcome timing, repeated measurements, analysis transparency, and interpretation of descriptive counts shape what can be concluded from a clinical study record.
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 most consequential limitation for interpreting the primary question is that numerical comfort results are not reported in the registry record. The outcome description supplies the scale and assessment timing, but no mean, standard deviation, contrast, or uncertainty estimate. The primary outcome is also described as having several categories or time points and not being reduced to one comparison. As a result, the comparative comfort result cannot be reconstructed from the record.
Details needed to assess the crossover analysis are not reported in the registry record. These include the randomized sequences, period-specific observations, any washout arrangement, handling of possible carryover, and the statistical method for repeated measurements. The analysis unit for the bilateral study is also not specified. These gaps matter because the interpretation of a crossover comparison can depend on how periods and related observations are handled.
The registry reports enrollment of 41, but the number included in each comfort analysis and the amount of missing outcome data are not reported in the registry record. The analysis populations, exclusions, and missing-data methods are also not reported. The record lists 22 outcome measures and 0 analyses, and does not describe a multiplicity strategy. These omissions limit assessment of both selective interpretation and the uncertainty of any potential result.
The safety fields list 40 participants at risk per lens group and zero affected participants in the serious and other adverse-event categories, while death counts are not reported in the registry record. Event definitions, follow-up completeness, and comparative safety methods are not described. The record also does not report the trial’s own sample-size justification. These limitations concern what can be assessed from the registry record; they do not establish that any particular design or analysis problem occurred.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Dispensing Clinical Trial of a Study Test Silicone Hydrogel Lens Against Control Lens Over 1 Week — NCT02500368.
- Registry record last updated 2020-07-29; status last verified 2020-07.
- Results first posted 2017-02-17.
- 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.
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18. Record Summary
NCT02500368 is a completed study sponsored by CooperVision, Inc., listed for myopia and described as a randomized, double-masked, bilateral crossover trial. Enrollment was 41. The recorded start was 2015-07, and primary completion was 2015-08. The study compared a silicone hydrogel test lens with an enfilcon A control lens over 1 week.
The primary outcome was comfort, a subjective rating on a 0-100 scale, assessed at baseline and at 1 week. The registry lists several assessment points and states that the outcome was not reduced to one comparison. It lists 22 outcome measures and 0 analyses. Numerical comfort results and the statistical analysis plan are not reported in the registry record.
Safety entries list 40 participants at risk in each lens group and 0 participants affected by serious or other adverse events in each group. Death counts are not reported in the registry record. The record identifies the study question and design but does not report a numerical comparative answer for comfort.