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 Multifocal Lens Design Evaluation (NCT01997216), a randomized na study. The primary outcome is Mean Binocular HC/HI Visual Acuity at Near (40 cm).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01997216 |
| Phase | NA |
| Condition | Refractive Error, Presbyopia |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Double |
| Enrollment | 42 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Alcon Research |
| Results posted | Yes |
2. Clinical Question
Population
Participants with refractive error and presbyopia who were enrolled and exposed to study product. The primary outcome population is described as all enrolled participants exposed to study product; one participant was not exposed to Delefilcon A MF because the product was unavailable.
Intervention
Delefilcon A multifocal contact lenses worn bilaterally for 9 hours.
Comparator
Lotrafilcon B multifocal contact lenses, identified as AOAMF and AIR OPTIX® AQUA MULTIFOCAL, worn bilaterally for 9 hours.
Primary question
How did binocular high contrast, high illumination visual acuity at near (40 centimeters) compare between the lens products at up to Hour 9?
The study was designed to compare visual acuity after each participant wore both lens products, with product order randomized. The primary question concerns a continuous measurement: near acuity expressed in logMAR units. The registry record defines the measurement conditions and endpoint, but does not report the numeric mean for either product or a statistical comparison between them. It therefore does not establish the direction or size of any observed difference.
The comparison is about visual acuity under the stated test conditions, not every aspect of contact-lens performance. Secondary outcomes listed in the record are mean binocular high contrast, high illumination visual acuity at distance and mean monocular over-refraction at distance. A result for those outcomes is not reported in the registry record. No conclusion about the comparative clinical value of the lenses can be drawn from the endpoint description alone.
3. Trial Design
This was a randomized, double-masked, crossover study of multifocal contact lenses. The registry record lists 42 enrolled participants and describes two possible product sequences: delefilcon A followed by lotrafilcon B, or lotrafilcon B followed by delefilcon A. Sequence was randomized. Each product was worn bilaterally for 9 hours, and the two wear periods were separated by 2 ± 1 days.
A crossover design means participants receive both products in a planned sequence, so the comparison can use measurements from the same participants under each product condition. This differs from a design in which participants are assigned to only one product. The participant may act as their own comparator, but measurements from the two periods are related rather than independent. The registry record does not describe the statistical model used to account for that relationship.
The record identifies Alcon Research as sponsor, lists the study as completed, and gives the study start as 2012-10 and primary completion as 2012-11. It identifies the interventions as delefilcon A and lotrafilcon B multifocal contact lenses. The primary endpoint was assessed at near, with a stated timeframe of up to Hour 9. Additional protocol details, including any rationale for the period separation, are not reported in the registry record.
Although the record labels the study randomized and double-masked, it does not describe the masking procedures or explain how randomization was generated or implemented. The record also does not report a planned sample-size justification, the intended treatment-effect estimand, or the full statistical analysis plan. These omissions limit what can be said about how the study was planned and how its comparison was intended to be analyzed.
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: Of the 42 participants enrolled, 1 participant was exited as a screen failure and 1 participant was discontinued due to product unavailability prior to study product exposure. This reporting group includes all enrolled participants exposed to study product (40).
First 9 Hours
| Stage | Delefilcon A MF, Then AOAMF | AOAMF, Then Delefilcon A MF |
|---|---|---|
| STARTED | 18 | 21 |
| COMPLETED | 18 | 21 |
| NOT COMPLETED | 0 | 0 |
Second 9 Hours
| Stage | Delefilcon A MF, Then AOAMF | AOAMF, Then Delefilcon A MF |
|---|---|---|
| STARTED | 19 | 21 |
| COMPLETED | 19 | 21 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: All enrolled participants exposed to study product. 1 participant was not exposed to Delefilcon A MF due to product unavailability.
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: This reporting group includes all enrolled participants exposed to study product.
| Characteristic | Unit | Overall |
|---|---|---|
| Participants analysed | 40 | |
| Age, Continuous | years | 52.1 (SD 6.0) |
| Sex: Female, Male: Female | Participants | 25 |
| Sex: Female, Male: Male | Participants | 15 |
6. Primary Endpoint
The registry lists the primary outcome as Mean Binocular HC/HI Visual Acuity at Near (40 cm), measured over Up to Hour 9.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | logMAR |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is mean binocular high contrast, high illumination visual acuity at near (40 cm), expressed in logMAR, with a timeframe of up to Hour 9. Participants read a Snellen chart at 40 centimeters using both eyes together while wearing study lenses. The Snellen acuity was converted to logMAR units.
This endpoint captures performance on a standardized near-vision task under the stated contrast and illumination conditions. The record explains that 20/20 Snellen acuity corresponds to logMAR 0.0 and is considered normal near eyesight; a negative logMAR value denotes better visual acuity. Those definitions help interpret the scale, but the registry record does not provide the observed endpoint means or a between-product estimate.
A mean summarizes the group’s measurements, while the standard deviation describes how spread out individual measurements are around that mean. Both can help characterize an endpoint, but neither is reported numerically for the primary outcome in the registry record. Nor is a confidence interval or test result for the product comparison reported. The endpoint definition alone therefore explains what was measured, not what the study found.
Visual acuity is only one measured aspect of lens performance. The record also lists distance visual acuity and monocular over-refraction at distance as secondary outcomes, but does not report their results. No broader conclusion about vision in other settings follows from the primary endpoint definition.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clinically interpretable measurement and a randomized crossover comparison, but it does not report the numeric primary outcome results. In particular, there is no posted mean for either lens condition, no estimated within-participant contrast, and no uncertainty interval or statistical test for the primary comparison. The record therefore does not show whether near acuity was numerically better with one lens, how large any difference was, or how precisely a difference was estimated.
The reported analysis listing contains no analyses. The primary outcome is explicitly not reduced to one comparison because it has several categories or time points. Consequently, the outcome description cannot be treated as a single reported endpoint result. The stated timeframe, up to Hour 9, does not supply a numeric result at a particular time. The record also does not report the values for the listed secondary outcomes.
For a continuous endpoint, a comparison is most informative when it includes an effect estimate and a measure of uncertainty, such as a confidence interval. A confidence interval describes a range of values compatible with the data and the analysis assumptions; it is not itself proof of benefit or equivalence. Without an estimate and its uncertainty, readers cannot judge the magnitude or precision of the comparison. A p-value alone, if it were available, would not convey the size of an effect, but no p-value is reported in the registry record.
The crossover structure is relevant to interpretation because each participant was scheduled to wear both products. A suitable analysis would generally need to respect the within-participant relationship and the order and period in which products were worn. The registry record does not state whether or how those features were incorporated into the analysis. It also does not report whether period effects or possible carryover were assessed.
The adverse-event figures are a separate type of information from the visual-acuity endpoint. The record reports zero serious and zero other adverse events among 39 participants at risk for Delefilcon A MF, and zero serious and zero other adverse events among 40 participants at risk for AOAMF. Death figures are not reported in the registry record. These counts describe the posted safety information; they do not fill the gap in the primary outcome results or establish a comparative visual-acuity effect.
Overall, the record permits description of the question, endpoint, sequence structure, and posted adverse-event counts. It does not support a quantified conclusion about the primary comparison. Any interpretation beyond those details would require results and analysis information that are not reported in the registry record.
9. Statistical Methods Explained
What kind of endpoint is this? The primary measure is continuous: it is a mean visual-acuity value on the logMAR scale. Continuous outcomes retain information about the magnitude of individual measurements rather than placing participants into categories such as improved or not improved. A group mean describes the center of the measurements, while a standard deviation describes their spread. The registry record identifies the mean and standard deviation as the measure and dispersion, but does not provide their numerical values for the primary endpoint.
What does logMAR express? The record states that Snellen acuity was converted to logMAR. It also gives the scale interpretation: 20/20 corresponds to logMAR 0.0 and is considered normal near eyesight, while a negative logMAR value denotes better visual acuity. These are properties of the stated measurement scale. They do not reveal the study’s observed scores or the difference between lens conditions.
Why does the crossover design matter statistically? In a crossover study, the same participant is measured under more than one condition. Measurements from that participant are usually related, so an analysis that treats all observations as independent may not represent the design appropriately. A paired comparison or a model that accounts for participant-level correlation is a general way to address this feature. This is general statistical explanation, not a description of the analysis used in this study: the statistical method is not reported in the registry record.
Order and period can also matter. Participants followed one of two randomized sequences, and product wear periods were separated by 2 ± 1 days. In general, a crossover analysis may need to consider whether outcomes differ by period or whether experience in an earlier period could influence a later measurement. The record does not say whether these issues were assessed, how they were handled, or what assumptions were made about them.
How should an effect estimate be read? A treatment contrast would express the difference in the endpoint between the two lens conditions under a defined analysis. Its sign would depend on the subtraction order, so the analysis must make clear which product is contrasted with which. A confidence interval around an estimate conveys uncertainty: a narrower interval indicates more precision under the model assumptions, while a wider interval indicates less precision. Neither an estimate nor an interval is reported for the primary comparison in the registry record.
A statistical test addresses compatibility between observed data and a specified null hypothesis under its assumptions. A p-value is not the probability that the null hypothesis is true, nor does it measure the size or importance of a difference. The registry record does not report a p-value or test for the primary endpoint. Without a reported effect estimate, uncertainty interval, and analysis details, readers cannot evaluate either the magnitude or statistical precision of a product contrast.
Why can variation matter? Visual-acuity measurements vary among participants, and the standard deviation is one way to describe that variation. General statistical reasoning is that greater variability can make an estimate less precise if other design features are unchanged. In a crossover comparison, the variability of within-participant differences may be especially relevant because the same person contributes measurements under both products. The registry record does not report the variability of those differences or the method used to estimate it.
Over-dispersion is a general issue in some statistical models for counts, where observed variation exceeds what a model assumes. It is not a stated feature of this continuous visual-acuity endpoint, and the registry record does not report an over-dispersion assessment. This concept therefore should not be used to characterize the trial’s endpoint analysis.
What does a planning illustration mean? Sample-size illustrations based on an observed effect are planning scenarios, not evidence that a study had a particular probability of detecting an effect. They depend on assumptions about the effect to detect, the significance level, allocation, and statistical approximation. The registry record describes planning illustrations as based on an observed effect and specifies general assumptions for them. Such illustrations are not the trial’s own design justification, and they are not observed power. The actual sample-size rationale is not reported in the registry record. Since no numeric observed primary effect is reported in the available record, a reader should not interpret a planning scenario as a substitute for the missing comparison result.
What analysis details are missing? The registry record does not report the statistical model, covariates, handling of within-participant correlation, treatment of period or sequence, missing-data method, or multiplicity procedure. These details can affect how an estimate is constructed and how its uncertainty is assessed. Their absence does not establish that no such methods were used; it means they are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The record lists one primary outcome title and two secondary outcome titles, and identifies three outcome measures in total. It also states that the primary outcome has several categories or time points and was not reduced to one comparison. No numeric result for those categories or time points is reported in the registry record. This makes it impossible to determine which individual comparisons, if any, were intended to carry the main inferential emphasis.
When an analysis examines multiple outcomes, time points, or comparisons, the chance of obtaining at least one apparently unusual result can increase. Statistical approaches to multiplicity can adjust the interpretation or testing procedure, or a plan can designate a limited set of primary comparisons in advance. This is general explanation; the registry record does not report a multiplicity strategy or a detailed hierarchy for outcomes and time points.
The record describes the primary outcome population as all enrolled participants exposed to study product and notes that one participant was not exposed to Delefilcon A MF because the product was unavailable. It does not explain how that participant was handled in the outcome analysis, whether all endpoint measurements were available, or how missing measurements were treated. An analysis population beyond the stated description is not reported in the registry record.
There is also no reported statistical analysis listing for the posted outcomes. Accordingly, the record does not allow readers to assess whether the analysis followed a prespecified plan, how repeated measurements were handled, or whether adjustment for multiple comparisons was used. These are reporting limitations, not evidence that a particular method was or was not used.
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 |
|---|---|---|---|
| Delefilcon A MF | 0 | 39 | 0.0% |
| AOAMF | 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 |
|---|---|
| Delefilcon A MF | 0 of 39 |
| AOAMF | 0 of 40 |
The registry record reports zero serious adverse events and zero other adverse events among 39 participants at risk for Delefilcon A MF. For AOAMF, it reports zero serious adverse events and zero other adverse events among 40 participants at risk. No serious adverse-event terms are listed. Death figures are not reported in the registry record.
These are descriptive counts for the safety groups as recorded. A count of zero reported events does not establish that an event is impossible, nor does it by itself establish that the products have equivalent safety. The figures do not include an uncertainty estimate or a comparative statistical analysis. The registry record also does not provide additional detail about event definitions, collection procedures, event timing, or the handling of participants with differing exposure.
The safety counts should be read separately from the primary visual-acuity outcome. They do not provide information about the mean near-acuity measurement or its comparison between lens products. Likewise, the lack of listed serious adverse-event terms should not be interpreted as a complete account of all possible adverse experiences beyond the registry’s reported figures.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, double-masked crossover study was conducted to compare near visual acuity with delefilcon A and lotrafilcon B multifocal contact lenses. It specifies bilateral wear for 9 hours, the near-vision measurement conditions, and a separation of 2 ± 1 days between wear periods. It also reports 42 enrolled participants and identifies one participant who was not exposed to Delefilcon A MF because of product unavailability.
Those design details do not answer whether one lens produced a higher or lower mean acuity, or how large any difference was. The registry record does not report numeric primary endpoint results, an estimate of the product contrast, a confidence interval, or a test result. The outcome is also not reduced to one comparison because it has several categories or time points. As a result, the record does not support a quantified conclusion about the primary question.
The posted safety counts show zero serious and zero other adverse events in the listed at-risk groups, but they are descriptive and do not establish comparative safety. The record does not provide death figures, and additional safety-analysis details are not reported. These counts should not be used as a substitute for missing visual-acuity results.
More generally, a study’s design and endpoint definitions describe what researchers set out to compare, whereas outcome estimates describe what the data showed. Interpretation of a continuous comparison normally depends on both the estimated difference and its uncertainty, alongside the analysis method and population. Those elements are not reported for the primary comparison.
The appropriate reading is therefore limited: the trial question and conduct are described, but the registry record does not provide enough outcome information to determine the direction, magnitude, or precision of the near-vision comparison. This limitation is about the information reported in the registry record, not a claim about whether other analyses or results exist elsewhere.
13. Why This Trial Matters Statistically
This study illustrates why identifying a trial design is not the same as having an interpretable result. A crossover design can make within-participant comparisons relevant, because participants are scheduled to wear both products. At the same time, it makes the relationship between measurements, product sequence, and period important to the analysis. The record describes randomized sequences and the interval between wear periods, but does not report the analysis used to account for those features.
The endpoint also highlights the importance of keeping measurement definition separate from outcome evidence. The record specifies binocular high contrast, high illumination near acuity, the logMAR scale, and the assessment timeframe. These details help define the research question and the meaning of a future estimate. They do not tell readers the observed mean or the difference between products.
For biostatistical interpretation, an estimate and its uncertainty are central. Without a reported contrast and interval, there is no basis in the registry record for assessing the size or precision of the primary comparison. The record’s statement that the outcome has several categories or time points and was not reduced to one comparison adds a further interpretive limitation: no single result can be identified as the reported primary contrast.
The record also distinguishes design details from analysis details that are not reported. It identifies enrollment and exposure information, but does not report the statistical plan, missing-data handling, multiplicity approach, or sample-size rationale. Recognizing these gaps prevents readers from treating assumptions or planning illustrations as observed findings. The central statistical lesson is to separate what a registry record says was measured from what it reports was estimated.
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 for interpreting the primary endpoint is that the registry record does not report numeric outcome values or a comparison estimate. It therefore gives no basis for describing the direction, size, or precision of the difference in mean binocular near visual acuity. The record states that the primary outcome has several categories or time points and was not reduced to one comparison, leaving the specific result of interest unresolved.
Several analysis details are also not reported in the registry record: the model, treatment of within-participant correlation, handling of product sequence or period, missing-data method, analysis population beyond the stated exposure description, and multiplicity approach. The record does not provide a sample-size justification or explain how any planning assumptions relate to the trial’s design. These omissions limit assessment of the analysis and its assumptions.
The exposure description notes that one participant was not exposed to Delefilcon A MF because the product was unavailable. The registry record does not explain how this participant was handled in the primary analysis or whether other endpoint measurements were missing. It also does not describe the masking procedures or randomization implementation.
For safety, the listed groups have zero serious and zero other adverse events, but death figures are not reported. Further details about safety ascertainment and analysis are also not reported. The listed counts should therefore be interpreted narrowly rather than as a complete characterization of all possible safety outcomes.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Multifocal Lens Design Evaluation — NCT01997216.
- Registry record last updated 2014-02-04; status last verified 2013-12.
- Results first posted 2014-02-04.
- 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.
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18. Record Summary
The record describes a completed randomized, double-masked crossover study comparing delefilcon A and lotrafilcon B multifocal contact lenses. It lists 42 enrolled participants and identifies Alcon Research as sponsor. Participants were assigned to product sequences; each product was worn bilaterally for 9 hours, with wear periods separated by 2 ± 1 days.
The primary outcome was mean binocular high contrast, high illumination visual acuity at near (40 cm), expressed in logMAR and assessed up to Hour 9. The stated population includes enrolled participants exposed to study product, with one participant not exposed to Delefilcon A MF because of product unavailability. The registry record does not report a numeric primary outcome comparison or the analysis used to produce one.
Secondary outcomes listed are mean binocular high contrast, high illumination visual acuity at distance and mean monocular over-refraction at distance. Safety counts report zero serious and zero other adverse events in each listed at-risk group; death figures are not reported in the registry record. The record does not report the statistical plan, missing-data handling, multiplicity procedure, or sample-size rationale.