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 Study Intended to Evaluate the Safety and Effectiveness of a Johnson & Johnson Vision Care Inc, (JJVCI) Contact Lens for Use on an Extended-wear Basis for up to 7 Days (6 Nights). (NCT00241280), a randomized na study. The primary outcome is Monocular Contact Lens Snellen Visual Acuity Worse Than 20/40.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00241280 |
| Phase | NA |
| Condition | Myopia |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 504 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Johnson & Johnson Vision Care, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
People with myopia enrolled in a US study of extended-wear contact lenses. The primary analysis population was narrower: subjects who completed all study visits without a major protocol deviation, with analyses conducted on their eyes.
Intervention
Galyfilcon A contact lenses, designated as the test intervention, worn for 7 days/6 nights.
Comparator
Etafilcon A contact lenses, designated as the control intervention, also worn for 7 days/6 nights.
Primary question
At the specified follow-up visits, what percentage of subject eyes in each group had monocular Snellen visual acuity worse than 20/40? The registry record identifies this as the primary outcome, but does not report its results.
The clinical question concerns a comparison of two contact lens devices under the same stated extended-wear schedule. The endpoint focuses on eyes with visual acuity below the stated threshold, rather than a mean visual-acuity score or a change from baseline. The listed follow-up visits extend from 24 hr through 52 weeks. The registry description says the percentage was reported at each study visit, so the intended comparison has repeated visit-specific results rather than one single summary value.
The record describes the study as intended to evaluate safety and effectiveness. The primary outcome addresses visual acuity; adverse-event entries provide separate safety information. These endpoints answer different questions and should not be treated as interchangeable. Without the actual visit-specific visual-acuity results, the record does not establish which group had a higher or lower percentage of eyes below the threshold, or how precise any difference was.
3. Trial Design
The registry describes a randomized, double-masked, parallel-group study sponsored by Johnson & Johnson Vision Care, Inc. The interventions were etafilcon A and galyfilcon A contact lenses. The control arm used etafilcon A and the test arm used galyfilcon A; both arm descriptions specify wearing the lens for 7 days/6 nights. The condition listed is myopia, and the brief summary describes the study as taking place in the US.
Enrollment is recorded as 504. The study started in 2005-09, had primary completion in 2006-10, and is marked completed. Its phase is listed as NA. Random allocation is intended to make the groups comparable on average at the point of assignment; it does not guarantee that all characteristics will be balanced in a particular trial. Double masking is intended to limit the influence of knowledge about assigned treatment on study conduct or outcome assessment. The record does not specify exactly who was masked or how masking was maintained.
A parallel design assigns participants to a study group and follows the groups over the study period, rather than having each participant receive both interventions in sequence. The outcome description refers to subject eyes, while the eligibility description for the primary analysis is based on subjects completing all visits without a major protocol deviation. The record does not explain how correlation between a subject's eyes was handled statistically.
The study's purpose and basic structure are identifiable, but several design details are not reported in the registry record. These include the randomization method, allocation concealment, masking procedures, eligibility criteria beyond the listed condition, and the planned statistical model. The registry entry also does not give a sample-size justification or a protocol-level account of how repeated visit measurements were 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: 504 Subjects were enrolled in this study. 1 subject did not meet the eligibility. 2 subjects were randomized to the control lens group, but were not dispensed lenses. 247 subjects were randomized to the Control lens and 254 subjects were randomized to the Test lens.
Overall Study
| Stage | Control: Etafilcon A | Test: Galyfilcon A |
|---|---|---|
| STARTED | 247 | 254 |
| COMPLETED | 199 | 186 |
| NOT COMPLETED | 48 | 68 |
Reasons for not completing this period:
| Reason | Control: Etafilcon A | Test: Galyfilcon A |
|---|---|---|
| Adverse Event | 2 | 6 |
| Discomfort | 11 | 16 |
| Pregnancy | 1 | 5 |
| Lost to Follow-up | 5 | 8 |
| Withdrawal by Subject | 7 | 4 |
| Protocol Violation | 4 | 10 |
| Relocation | 4 | 4 |
| Unsatisfactory Physiological Response | 1 | 1 |
| Unsatisfactory Visual Response | 1 | 1 |
| Diabetic | 1 | 0 |
| Subject Ineligible/Dispensed | 9 | 6 |
| Dispensed incorrect test article | 1 | 2 |
Analysis population for the primary outcome, as defined in the registry: The analysis population consists of subjects that completed all study visits, without a major protocol deviation. The analysis was conducted on these subject eyes.
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: The baseline population consists of subjects that were randomized to receive either the Test or Control lens.
| Characteristic | Unit | Control: Etafilcon A | Test: Galyfilcon A | Total |
|---|---|---|---|---|
| Participants analysed | 247 | 254 | 501 | |
| Age, Continuous | years | 31.7 (18 to 51) | 32.8 (18 to 60) | 32.2 (18 to 60) |
| Sex: Female, Male: Female | Participants | 150 | 172 | 322 |
| Sex: Female, Male: Male | Participants | 97 | 82 | 179 |
| Race/Ethnicity, Customized: Asian | participants | 11 | 10 | 21 |
| Race/Ethnicity, Customized: White | participants | 203 | 217 | 420 |
| Race/Ethnicity, Customized: African-American | participants | 16 | 13 | 29 |
| Race/Ethnicity, Customized: Hispanic | participants | 12 | 13 | 25 |
| Race/Ethnicity, Customized: Asian-Indian | participants | 1 | 1 | 2 |
| Race/Ethnicity, Customized: Other | participants | 4 | 0 | 4 |
| Region of Enrollment: United States | participants | 247 | 254 | 501 |
6. Primary Endpoint
The registry lists the primary outcome as Monocular Contact Lens Snellen Visual Acuity Worse Than 20/40, measured over Follow-up Visits- 24 hr, 1, 4, 12, 24,36, and 52 weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Percentage of Subjects Eyes |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the percentage of subject eyes with monocular contact-lens Snellen visual acuity worse than 20/40. The outcome description says this percentage was reported at each study visit, with follow-up at 24 hr, 1, 4, 12, 24,36, and 52 weeks. This is a threshold-based endpoint: each eye is classified according to whether its measured acuity falls on the worse-than-20/40 side of the stated cutoff, and the endpoint expresses the frequency of such eyes as a percentage.
A threshold outcome can be clinically interpretable because it describes how often an eye crosses a defined visual-acuity boundary, rather than describing only an average score. It can also conceal variation within categories: eyes on the same side of the threshold may have different measured acuity, and a small change near the cutoff may change classification. Those are general properties of threshold endpoints, not findings from this study.
The registry identifies the analysis population as subjects who completed all study visits without a major protocol deviation, and says the analysis was conducted on those subject eyes. It does not report the visit-specific percentages, denominators, uncertainty estimates, or a comparison between groups. Therefore, the endpoint's definition and measurement schedule can be described, but the trial's primary outcome findings cannot be interpreted from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the primary outcome and its follow-up schedule, but it does not include the actual visual-acuity results. It gives no visit-specific percentage of eyes with acuity worse than 20/40, no group comparison, and no confidence interval or other uncertainty estimate for this endpoint. The record also lists zero analysis entries. Consequently, the primary result cannot be characterized as favoring either lens, and its precision cannot be assessed.
The outcome was to be assessed at 24 hr, 1, 4, 12, 24,36, and 52 weeks. Repeated measurements can reveal whether results vary over follow-up, but they also create a set of related comparisons. A conclusion based on one visit could differ from a conclusion based on another. The registry record does not state which visit, if any, was designated as the main comparison point, nor does it report an overall analysis across visits.
The adverse-event entries are available separately from the primary endpoint. The record lists 0 serious adverse events among 247 at risk in the control group and 1 among 254 at risk in the test group. For other adverse events, it lists 23 among 247 at risk in the control group and 43 among 254 at risk in the test group. These are descriptive registry counts; the record does not give uncertainty estimates or an inferential comparison for them. A difference in counts alone does not establish whether an underlying group difference is reliable, and the counts cannot substitute for the unreported visual-acuity results.
The record names iritis with a reported value of 0.4% among the top serious-event terms. It does not provide further event-level context in the information available, such as timing, duration, or relationship to the study intervention. Deaths are not reported in the registry record. The absence of reported deaths should not be interpreted as evidence about events beyond what the record documents.
Overall, the study design and endpoint definition are recorded, as are selected adverse-event counts. The primary effectiveness outcome is not reported in a form that permits a statistical comparison. No conclusion about comparative visual acuity, the size of an effect, or its precision follows from the record alone.
9. Statistical Methods Explained
The design and outcome fields permit a limited explanation of the statistical questions, but the registry record does not report the analysis methods used for the primary endpoint. It lists no analysis entries. The following concepts explain how such data are commonly considered in general; they should not be read as a description of an analysis performed in this trial.
What does randomization contribute?
In general, random assignment helps make treatment groups comparable with respect to both measured and unmeasured characteristics, on average. This supports interpretation of group comparisons, provided assignment is implemented as intended and outcome data are adequately collected and analyzed. Randomization does not itself remove bias from missing outcomes, departures from the assigned treatment, or selective reporting. The registry identifies the allocation as randomized but does not describe the sequence-generation or concealment procedures.
What is being compared for the primary endpoint?
The endpoint classifies subject eyes according to whether monocular Snellen acuity is worse than 20/40, then describes the percentage meeting that criterion at each listed visit. In general, a group comparison might present the proportions in each arm and an estimate of the difference or another contrast, with an interval expressing uncertainty. A confidence interval describes a range of values compatible with the data and analysis assumptions; it is not a guarantee that the true value lies in that range. No such estimates or intervals for the primary outcome are reported in the registry record.
Because the endpoint is expressed as a percentage of eyes, the handling of the denominator matters. The analysis description says the population consists of subjects who completed all visits without a major protocol deviation and that analyses were conducted on subject eyes. It does not report the number of eligible subjects or eyes at any visit, how eyes with missing measurements were handled, or whether each subject contributed one eye or both. When two eyes from the same subject are included, their outcomes may be correlated. In general, treating correlated observations as independent can make uncertainty appear smaller than it is; methods that account for within-subject correlation may be appropriate. The registry record does not say whether such methods were used.
Why can repeated visits complicate interpretation?
Measurements at several follow-up visits are usually related because they come from the same study population over time. In general, analyzing each visit separately creates multiple opportunities to observe an apparently notable result by chance. A prespecified primary time point or a suitable adjustment for multiple comparisons can help control the interpretation of a family of tests. The registry record gives the visit schedule but does not identify a single primary time point, an adjustment method, or whether an overall repeated-measures model was planned or used.
What can the safety counts establish?
Adverse-event counts describe events recorded in the registry, but counts alone do not convey sampling uncertainty or establish a causal relationship. In general, comparison of safety outcomes depends on clear event definitions, the period and population under observation, and an appropriate account of participants at risk. The record lists the at-risk and affected counts for serious and other adverse events, but does not provide confidence intervals, hypothesis tests, event timing, or detailed definitions for the other-event category. The listed figures should therefore be read descriptively.
How should the planning assumptions be read?
The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It states that the effect to detect is expressed as a fraction of the observed effect. Such sample-size calculations are planning illustrations, not observed trial findings and not observed power. Their usefulness depends on a clearly specified outcome and effect estimate. The primary outcome has several categories or time points and is not reduced to one comparison in the record, so these registry entries do not establish a single primary comparison for interpreting a planning estimate. The registry record does not report the trial's own sample-size justification or a detailed statistical analysis plan.
10. Multiplicity, Missing Data and Analysis Populations
The primary outcome is described across several follow-up visits: 24 hr, 1, 4, 12, 24,36, and 52 weeks. A series of visit-specific comparisons raises a multiplicity question. In general, the more comparisons considered, the greater the chance that at least one may look notable by chance alone. A prespecified primary visit, a global longitudinal analysis, or an adjustment for multiple comparisons may address this issue, depending on the scientific question and analysis plan. The registry record does not report which approach, if any, was used.
The record also describes the primary analysis population as subjects who completed all study visits without a major protocol deviation, with analysis conducted on their eyes. This is a completer population rather than an explicitly described analysis of all randomized subjects. The registry does not state how many subjects or eyes met this criterion, how missing visit measurements were handled, or whether subjects with protocol deviations were included in other analyses. A completer analysis can be vulnerable to bias if completion is related to treatment assignment or outcome; that is a general concern, not a claim that such bias occurred in this study.
Other unreported analysis details include the handling of dependence between eyes from the same subject, the statistical model, the treatment of repeated measurements, and any sensitivity analyses. The registry lists no analysis entries and does not report an interim-analysis plan or a multiplicity procedure. These omissions prevent assessment of whether the analysis choices were prespecified and how they affect interpretation.
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 |
|---|---|---|---|
| Control: Etafilcon A | 0 | 247 | 0.0% |
| Test: Galyfilcon A | 1 | 254 | 0.4% |
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 |
|---|---|
| Control: Etafilcon A | 23 of 247 |
| Test: Galyfilcon A | 43 of 254 |
Most frequent serious adverse event terms
| Event term | Organ system | Control: Etafilcon A | Test: Galyfilcon A |
|---|---|---|---|
| IRITIS | Eye disorders | 0 of 247 | 1 of 254 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Control: Etafilcon A | Test: Galyfilcon A |
|---|---|---|---|
| Conjunctivitis | Eye disorders | 21 of 247 | 31 of 254 |
| CLPU | Eye disorders | 2 of 247 | 12 of 254 |
Serious events with the highest arm-level rate: iritis (0.4%).
The registry lists serious adverse-event counts with at-risk counts for each group. For control, it records 0 serious adverse events among 247 at risk; for test, it records 1 among 254 at risk. For other adverse events, it records 23 among 247 at risk in control and 43 among 254 at risk in test. These figures describe the entries in the registry and are not, by themselves, estimates of a causal treatment effect.
The record identifies iritis as a top serious-event term and reports 0.4%. It does not explain the clinical context or provide further detail about that term. The deaths field has no reported value, so deaths are not reported in the registry record.
Counts should be read alongside definitions, follow-up duration, and uncertainty. The registry information does not give confidence intervals or statistical tests for these safety counts, nor does it provide detail on event timing or relatedness. The serious and other-event categories should remain distinct: the record reports them separately, and one category should not be treated as a substitute for the other. These figures do not resolve the primary visual-acuity question.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, double-masked, parallel study compared etafilcon A with galyfilcon A during a stated schedule of 7 days/6 nights of lens wear. It identifies myopia as the condition, records enrollment of 504, and defines a primary visual-acuity endpoint at several follow-up visits. It also contains selected serious and other adverse-event counts.
What it does not establish is the primary outcome result. The visit-specific percentages of eyes with acuity worse than 20/40 are not reported, and no comparison estimate or uncertainty interval is given. As a result, the registry record does not support a conclusion that either lens group had better or worse visual acuity, nor does it show how precisely such a comparison was estimated. The recorded safety counts are descriptive and lack reported inferential estimates; they should not be used to fill the gap in the primary outcome reporting.
More generally, a study design can make a comparison meaningful without making its result available. Randomization and masking describe features intended to support fair assessment, while outcome data and an analysis are needed to estimate the observed group contrast. Even a reported difference would need to be interpreted in light of uncertainty, the analysis population, missing data, repeated visits, and the handling of subject eyes. Those details are not fully documented in the registry record.
The study's intended purpose is not itself a result. A registered aim to evaluate safety and effectiveness cannot establish either. The appropriate reading is limited: the record documents the comparison and some safety counts, but it does not report the central visual-acuity findings needed to judge the primary question.
13. Why This Trial Matters Statistically
This trial illustrates why a clear endpoint definition is not enough for statistical interpretation. The record specifies a threshold-based visual-acuity outcome, its measurement scale, the population used for analysis, and a schedule of follow-up visits. Those details explain what investigators intended to measure. Without the observed values for each group, however, neither the direction nor magnitude of the primary comparison is available.
It also illustrates the importance of aligning the analysis population with the study question. The stated primary population consists of subjects who completed all visits without a major protocol deviation, while the study itself is described as randomized. In general, restricting analysis after randomization can change the balance created by random assignment, particularly if completion or protocol deviations are associated with outcomes. Whether that concern affected this study cannot be determined from the registry record; the inclusion details and analyses are not reported.
The endpoint is measured at several visits and is based on subject eyes. This raises familiar statistical issues: multiple comparisons across visits, repeated measurements over time, and possible correlation between eyes belonging to the same subject. These are not merely technical details. They can affect the estimated uncertainty and the interpretation of any apparent group contrast. The record does not say how these issues were handled.
Finally, safety counts and effectiveness outcomes answer distinct questions. Recording adverse events does not supply missing visual-acuity results, and the existence of a randomized design does not replace an analysis. The study is therefore useful as an example of how registry fields can document a trial's structure while leaving key information needed for outcome interpretation unreported.
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 interpretation is that the primary visual-acuity results are not reported. There are no visit-specific percentages, group contrasts, or uncertainty estimates in the registry record. This prevents assessment of the primary question, including the direction, size, and precision of any observed difference.
The analysis population is restricted to subjects who completed all study visits without a major protocol deviation. The record does not report how many subjects or eyes were included, whether the criteria were applied consistently across groups, or how missing measurements and protocol deviations were handled. It also does not explain the statistical treatment of eyes within the same subject, an important issue for an eye-level endpoint.
The outcome has multiple follow-up visits, but a primary comparison time point and multiplicity approach are not reported. The registry record also does not give the statistical model, confidence intervals, hypothesis tests, sensitivity analyses, or an account of interim analyses. The planning assumptions listed in the record do not replace a trial-specific sample-size justification or analysis plan.
Safety information is limited to the listed event counts and the top serious-event term. Event timing, severity detail beyond the serious/other categories, relationship to intervention, and inferential comparisons are not included in the record. Deaths are not reported in the registry record. These limitations concern what the registry documents; they do not establish that the unreported methods or information were absent from other study materials.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study Intended to Evaluate the Safety and Effectiveness of a Johnson & Johnson Vision Care Inc, (JJVCI) Contact Lens for Use on an Extended-wear Basis for up to 7 Days (6 Nights). — NCT00241280.
- Registry record last updated 2016-03-24; status last verified 2016-02.
- Results first posted 2016-02-25.
- 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 completed study, sponsored by Johnson & Johnson Vision Care, Inc., was a randomized, double-masked, parallel comparison of etafilcon A and galyfilcon A contact lenses for extended wear of 7 days/6 nights. It lists myopia as the condition, enrollment of 504, a start in 2005-09, and primary completion in 2006-10.
The primary endpoint was the percentage of subject eyes with monocular Snellen visual acuity worse than 20/40 across follow-up visits from 24 hr to 52 weeks. The stated primary analysis population comprised subjects who completed all visits without a major protocol deviation. The registry record does not report primary endpoint results or analysis estimates.
Safety entries list serious and other adverse-event counts by group, and iritis is named among the top serious-event terms. The registry record lists no analysis entries. Important statistical details, including missing-data handling, multiplicity methods, and treatment of eye-level observations, are not reported.