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 Clinical Validation Study of Comfilcon A Multifocal Toric Contact Lenses (NCT03417557), a randomized na study. The primary outcome is Visual Acuity.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03417557 |
| Phase | NA |
| Condition | Presbyopia |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Single |
| Enrollment | 20 |
| Arms in the primary outcome | n/a |
| Lead sponsor | CooperVision, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
Participants with presbyopia were enrolled. The registry record lists planned enrollment of 20, but the specific characteristics of the participants and the population included in the primary outcome analysis are not reported in the registry record.
Intervention
The test intervention was a Comfilcon A multifocal toric contact lens. Participants were randomized to wear it for up to 3 hours, either as the first or second lens in the crossover study.
Comparator
The control intervention was an Omafilcon B lens. Participants were randomized to wear it for up to 3 hours, either as the first or second lens. Further details about the lens-wearing procedures are not reported in the registry record.
Primary question
The primary outcome was visual acuity, assessed for the test and control lenses using a logMAR chart. The registry describes the measure as a mean with standard deviation and gives a timeframe of up to 3 hours. The central question is how visual acuity measurements compare between lenses during this short, in-office evaluation. The registry record does not report the outcome values or an estimated comparison, so the direction, size, and precision of any observed difference cannot be described.
3. Trial Design
This was a randomized, single-masked, crossover study of two contact lenses. The test lens was Comfilcon A and the control lens was Omafilcon B. In a crossover design, participants receive or use each intervention in sequence, so comparisons can be made within the same participant as well as between intervention periods. The registry describes participants as randomized to wear each lens for up to 3 hours, either as the first or second lens. It does not report the randomization sequence method, allocation concealment, or who was masked.
The study was conducted in an in-office setting and enrolled participants with presbyopia. Planned enrollment was 20. The registry record gives a start date of 2018-01-12, a primary completion date of 2018-04-03, and a status of completed. It lists the study phase as NA. The lens-wearing period is described as up to 3 hours; details of any visit schedule, washout interval, or procedures between periods are not reported in the registry record.
Visual acuity was the primary outcome. The listed secondary outcomes concern subjective assessments of distance daytime navigation, intermediate or computer tasks, and near vision, each described in terms of vision quality and clarity. The registry lists four outcome measures and no analysis entries. It does not report results for the primary or secondary outcomes. Thus, the design and intended assessments can be described, but the record does not allow a numerical comparison of the lenses or an assessment of how the planned crossover analysis was carried out.
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: Three subjects did not meet the inclusion criteria. Seventeen (17) subjects completed all visits and were included in the analysis.
1st Intervention (3 Hours)
| Stage | Comfilcon A Lens Then Omafilcon B Lens | Omafilcon B Lens Then Comfilcon A |
|---|---|---|
| STARTED | 8 | 9 |
| COMPLETED | 8 | 9 |
| NOT COMPLETED | 0 | 0 |
2nd Intervention (3 Hours)
| Stage | Comfilcon A Lens Then Omafilcon B Lens | Omafilcon B Lens Then Comfilcon A |
|---|---|---|
| STARTED | 9 | 8 |
| COMPLETED | 9 | 8 |
| 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 | Comfilcon A Lens (Test) and Omafilcon B (Control) |
|---|---|---|
| Participants analysed | 17 | |
| Age, Continuous | years | 54 (SD 7) |
| Sex: Female, Male: Female | Participants | 11 |
| Sex: Female, Male: Male | Participants | 6 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 17 |
6. Primary Endpoint
The registry lists the primary outcome as Visual Acuity, measured over up to 3 hours.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | logMAR |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is visual acuity, measured on a logMAR chart for the test and control lenses. The registry identifies the summary measure as a mean and the accompanying measure of variability as a standard deviation, with assessment occurring up to 3 hours. These details define what was intended to be measured and the scale on which the assessment was recorded; they do not provide the observed scores.
Visual acuity is a measure of visual performance under a specified assessment condition. In this study, it offers a quantitative way to compare vision while participants wore each lens. A mean describes the central value of a set of measurements, while a standard deviation describes their spread around that mean. Those summaries can help characterize each lens condition, but a comparison also requires the actual values and an estimate of uncertainty. Neither the outcome values nor an estimated test-versus-control difference is reported in the registry record.
The registry also lists subjective assessments of distance, intermediate or computer, and near vision as secondary outcomes. These capture participant assessments distinct from the chart-based primary endpoint. Their results are not reported in the registry record, so they cannot establish whether subjective ratings differed between lenses.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a randomized crossover comparison of a Comfilcon A test lens and an Omafilcon B control lens in participants with presbyopia. Its primary outcome is visual acuity on a logMAR chart, summarized as a mean and standard deviation over a timeframe of up to 3 hours. Those design details describe the planned measurement, not the result. The registry record does not report visual-acuity values, a between-lens estimate, a confidence interval, or a p-value. Consequently, neither the direction nor the magnitude of the observed comparison can be stated.
The record lists planned enrollment of 20, but that number is not a substitute for the number contributing to an outcome analysis. For the adverse-event summaries, 17 participants are listed at risk in each lens group. Those safety figures should not be taken as the primary-outcome analysis population: the registry record does not report the number analyzed for visual acuity or explain how participants moved through the crossover periods.
A crossover design can make within-participant comparisons possible because each participant wears both interventions. General statistical interpretation of such a comparison depends on the design and analysis accounting for the pairing and the order of the lens periods. The registry describes randomized order but does not report the statistical model, period or sequence effects, or the handling of missing measurements. It is therefore not possible to determine from the registry record whether the reported analysis, if any, addressed those features.
The record lists three subjective secondary outcomes in addition to the primary visual-acuity outcome. It does not report their results or whether the analysis accounted for multiple outcome comparisons. No analysis entries are listed. The registry's completed status indicates that the study is recorded as completed, but completion alone does not provide evidence about the outcome values or the precision of the comparison.
For these reasons, the available record supports a description of the trial question and design, but not a conclusion about the comparative results. General statistical interpretation would require the lens-specific outcome summaries, the estimated contrast, its uncertainty, and the analysis population. Those details are not reported in the registry record. No clinical judgment about either lens follows from the design information alone.
9. Statistical Methods Explained
The registry describes a randomized, single-masked crossover study. Randomization assigns the order in which participants receive or wear interventions; in a crossover, each participant experiences both conditions. The record says participants were randomized to wear each lens for up to 3 hours, either as the first or second lens. It does not identify who was masked, how the random sequence was generated, or how allocation was concealed. These are distinct design details and are not reported in the registry record.
What does a crossover comparison involve?
General statistical explanation: a crossover design can compare each participant's measurement under one intervention with that same participant's measurement under another. Because observations from one person are often related, an analysis may account for within-participant pairing rather than treating all observations as independent. This can be useful when individual differences influence the measured outcome. The appropriate method also depends on the data structure and trial procedures. The actual statistical method used for this study is not reported in the registry record.
Order and period can matter in a crossover. A period effect is a change associated with when an intervention is received, while a sequence effect concerns the order of interventions. A carryover effect means the experience of one intervention may influence measurements in a later period. General explanation: crossover analyses may examine or otherwise address such design features when relevant. The record specifies randomized first-or-second lens order but does not report a washout interval, an assessment of carryover, or how period and sequence were handled.
How should the primary outcome be understood?
The primary endpoint is visual acuity assessed with a logMAR chart. The registry describes the outcome as a mean with standard deviation. General explanation: a mean summarizes the center of measured values, and a standard deviation describes how dispersed those values are around the mean. Neither summary by itself gives the uncertainty in the comparison between lenses. An estimated difference and a confidence interval would help show both the size of the comparison and its precision. These estimates are not reported in the registry record.
A confidence interval is a range of values generated by a statistical procedure to express uncertainty about an estimated effect. General explanation: a narrower interval indicates greater precision than a wider interval, while the interval's location describes which effect values are compatible with the data under the method's assumptions. No confidence interval is reported for visual acuity or the secondary outcomes, so precision cannot be evaluated from the registry record.
What does the record say about statistical testing?
The registry lists no analysis entries. It does not report a statistical model, hypothesis test, significance threshold, covariate adjustment, or a prespecified approach to the crossover structure. The record also does not report a sample-size justification or the assumptions used in designing the trial. Those omissions mean that the analysis plan cannot be reconstructed from the registry record.
General explanation: a statistical test can assess how compatible observed data are with a specified null hypothesis under stated assumptions. A p-value, when reported, is not a measure of the size or clinical importance of an effect. A test result should be interpreted alongside the estimated effect, its uncertainty, and the design. Since the registry does not report an estimate or a p-value, no statistical significance claim can be made.
The record includes a planning illustration framework based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such illustrations are hypothetical planning calculations, not observed power and not the trial's own design justification. The observed effect and the resulting planning quantities are not reported in this record, so no numerical planning result can be stated. In a crossover study, any sample-size planning also needs assumptions suited to the within-participant comparison; the record does not report those assumptions.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists visual acuity as the primary outcome and three subjective secondary outcomes: distance daytime navigation, intermediate or computer tasks, and near vision. These concern vision quality and clarity. The record lists four outcome measures in total, but no analysis entries. It does not report whether one outcome was designated as the primary statistical test, how the secondary outcomes were tested, or whether any adjustment for multiple comparisons was planned or performed.
General explanation: when several outcomes are tested, the chance of finding at least one apparently unusual result can increase if each test is interpreted separately. A multiplicity strategy may define a hierarchy among outcomes, adjust testing thresholds, or treat secondary analyses as exploratory. The registry record does not describe such a strategy. Because no outcome results or analysis details are reported, it is not possible to assess the implications of multiple testing for this study.
Missing-data handling is also not reported in the registry record. The record does not state how many participants contributed measurements to each outcome, how missing measurements were handled, or whether any sensitivity analyses were planned. Planned enrollment of 20 does not establish the number with complete data or the analysis population. The 17 participants listed at risk for each lens in the adverse-event summaries refer to those summaries and do not identify the population used for visual-acuity or subjective-outcome analyses.
The registry does not report the analysis population definition, exclusions from analysis, or whether all randomized participants were included in any analysis. It is therefore not possible to characterize the primary analysis as intention-to-treat, per-protocol, or another approach. These details matter for understanding the population to which an estimate applies, but the record does not give the information needed to determine them.
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 |
|---|---|---|---|
| Comfilcon A Lens (Test) | 0 | 17 | 0.0% |
| Omafilcon B Lens (Control) | 0 | 17 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Comfilcon A Lens (Test) | 0 of 17 |
| Omafilcon B Lens (Control) | 0 of 17 |
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 |
|---|---|
| Comfilcon A Lens (Test) | 0 of 17 |
| Omafilcon B Lens (Control) | 0 of 17 |
The adverse-event record lists 17 participants at risk for serious adverse events in the Comfilcon A lens group and 17 in the Omafilcon B lens group. It reports 0 serious adverse events in each group. It also reports 0 other adverse events and 0 deaths in each group. These are the counts recorded for the listed groups; they are not measures of the visual-acuity outcome.
The at-risk counts are distinct from planned enrollment of 20. The registry record does not explain the difference between planned enrollment and the counts at risk, identify the safety analysis population, or provide further detail about event collection. It also does not report event definitions, severity criteria, or additional follow-up beyond the study timeframe described for the primary outcome. The reported zeros therefore describe the registry's listed safety counts and do not establish that no events occurred outside the recorded groups or period.
Zero recorded events in these summaries do not by themselves quantify the uncertainty around event occurrence. The registry record does not report a safety analysis or an interval estimate. The safety counts should be read descriptively and separately from the unreported efficacy outcomes; they do not provide an estimate of the comparative visual-acuity result.
12. What the Result Does, and Does Not, Mean
This registry record establishes that a randomized, single-masked crossover study was conducted to evaluate a Comfilcon A test lens against an Omafilcon B control lens in participants with presbyopia. It specifies visual acuity measured on a logMAR chart as the primary outcome, with a timeframe of up to 3 hours. It also lists subjective assessments of distance, intermediate or computer, and near vision. These registry entries define the study question and the intended measurements.
The record does not report the visual-acuity values, subjective outcome results, estimated differences, confidence intervals, or p-values. It therefore does not show whether measurements were higher or lower with either lens, how large any difference was, or how precisely the comparison was estimated. Without results, the comparative effect cannot be described as statistically significant or not statistically significant.
The study's completed status does not fill that gap. Completion indicates the registry status, not that results are available in the record. Likewise, planned enrollment of 20 does not establish how many participants contributed to each outcome, and the adverse-event at-risk counts do not supply the missing efficacy analysis population.
General statistical interpretation: a numerical outcome estimate is most informative when paired with an uncertainty interval, a clear description of the analysis population, and methods aligned with the randomized crossover design. Those details would help readers assess the size, precision, and robustness of a comparison. They are not reported in the registry record. The design alone cannot establish a result or support a clinical recommendation.
13. Why This Trial Matters Statistically
This study is statistically notable for its crossover structure. Each participant was scheduled to wear both the test and control lenses, with randomized order. General statistical explanation: within-participant comparisons can account for some differences between individuals because each person serves as a comparison for their own measurements. That advantage depends on having complete, interpretable measurements and an analysis that respects the pairing and sequence of exposures.
The record also illustrates why design information and outcome reporting answer different questions. The registry identifies the primary measurement, scale, and timeframe, as well as the interventions and randomization. But it does not report the actual outcome values or analysis. Without an estimated contrast and its uncertainty, readers cannot assess either the magnitude or precision of the comparison. A clear outcome definition is not a substitute for results.
The listed secondary assessments extend beyond chart-based visual acuity to subjective judgments of distance, intermediate or computer, and near vision. Considering several outcomes raises questions about how results were prioritized and how multiplicity was handled. The registry does not report its approach. Its absence of analysis entries also leaves key issues unresolved, including analysis populations, missing data, and the statistical treatment of crossover periods.
These features make the record useful for understanding the trial's intended question, while also making clear the limits of what can be inferred. The data summaries needed to interpret the comparison and evaluate its precision are not reported in the registry record. The trial's design can be described, but its comparative findings cannot be reconstructed from the registered information.
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 principal limitation of the registry information is that it does not report outcome results. There are no visual-acuity means or standard deviations, no comparison estimate, and no uncertainty interval. The three listed subjective secondary outcomes also have no reported results. This prevents assessment of the direction, magnitude, or precision of any difference between lenses.
The registry lists no analysis entries. It does not report the statistical model, how within-participant pairing was handled, or whether order, period, or carryover effects were considered. Although the order of lens use was randomized, the sequence-generation procedure and allocation concealment are not reported. The identity of the person or people masked is also not reported.
The record does not report a sample-size justification, the number analyzed for each outcome, missing-data handling, or analysis population definitions. Planned enrollment of 20 should not be assumed to equal the number with outcome data. The at-risk counts in the adverse-event summaries are not identified as the efficacy analysis population.
The duration described for the primary endpoint is up to 3 hours, and the study is described as an in-office evaluation. The registry does not report longer-term outcomes or further follow-up details. It also does not describe the procedures between lens periods or a washout interval. These gaps limit interpretation of how the crossover was implemented and what period of use the measured outcomes represent.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Clinical Validation Study of Comfilcon A Multifocal Toric Contact Lenses — NCT03417557.
- Registry record last updated 2020-05-04; status last verified 2020-04.
- Results first posted 2020-05-04.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry describes a completed, randomized, single-masked crossover study of Comfilcon A test lenses and Omafilcon B control lenses in participants with presbyopia. Planned enrollment was 20. Each lens was to be worn for up to 3 hours, with participants randomized to wear it first or second. The registry gives a start date of 2018-01-12 and a primary completion date of 2018-04-03.
Visual acuity on a logMAR chart was the primary outcome, summarized as a mean and standard deviation. Three subjective vision assessments were listed as secondary outcomes. The registry record does not report outcome results or analysis entries. Safety summaries list 17 participants at risk in each lens group, with 0 serious adverse events, 0 other adverse events, and 0 deaths reported in each group.