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 Visual Function After Implantation of Bilateral AcrySof® Toric Natural Intraocular Lens (NCT00760487), a non-randomized phase 4 study. The primary outcome is Visual Acuity (VA).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00760487 |
| Phase | Phase 4 |
| Condition | Cataract |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 120 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Alcon Research |
| Results posted | Yes |
2. Clinical Question
Population
The registry record identifies cataract as the condition and lists enrollment of 120. It does not report participant eligibility criteria, baseline characteristics, or a more detailed description of the population contributing to the visual acuity outcome.
Intervention
The intervention is the AcrySof Toric intraocular lens. The study title specifies bilateral implantation. The registry’s stated purpose is to evaluate how lens placement and power relate to postoperative visual acuity and spectacle independence for distance vision, and to evaluate lens rotational stability over time.
Comparator
The study is recorded as a single-group, non-randomized study with no masking. No comparator group is identified in the registry record. Its design therefore does not provide a like-for-like control comparison between the lens and another treatment or an untreated group.
Primary question
The primary outcome is mean visual acuity measured in logMAR before surgery and at 1 month, 3 month, and 6 month post-operative. The registry’s stated question is about visual acuity after implantation; the record does not report the outcome values or a numerical estimate of change.
In practical terms, the study asks how visual acuity is described across the recorded assessment times following implantation, while also considering spectacle independence for distance vision and IOL rotation as secondary outcomes. The registry summary mentions comparing manifest refraction before and after surgery, but does not provide the resulting measurements. Because there is no comparator group, the record cannot answer a randomized comparative-effectiveness question. It also does not report enough information to determine whether the recorded results support a causal interpretation. The clinical question is therefore descriptive: what visual acuity and related outcomes were recorded in this single-group study, and how precisely were they estimated? Numerical answers to those questions are not reported in the registry record.
3. Trial Design
The record identifies this as a PHASE4 study of the AcrySof Toric intraocular lens for cataract, sponsored by Alcon Research. Enrollment is listed as 120. The study is marked completed, with a start date of 2006-10 and a primary completion date of 2008-06. These dates describe the registry record; they do not, by themselves, establish when every participant was assessed or how long each participant was followed.
The design is classified as single-group and non-randomized, with no masking. These features matter for interpretation. A single-group study can describe outcomes in people who received the intervention, but it does not directly compare those outcomes with a concurrent control group. Without random allocation, differences between groups cannot be balanced by the design; in this record, no separate group is listed in any case. The registry’s planning illustration assumptions mention equal allocation between two arms, but those are planning assumptions rather than a description of the trial’s actual design.
The intervention is recorded as a device: AcrySof Toric IOL. The primary outcome is visual acuity in logMAR, summarized as a mean with standard deviation. Assessments are listed as pre-operative and at 1 month, 3 month, and 6 month post-operative. The stated purpose also refers to manifest refraction, spectacle independence for distance vision, and rotational stability. Spectacle Independence and IOL Rotation appear as secondary outcomes.
The record lists three outcome measures and zero analyses. It does not report the protocol, eligibility criteria, recruitment details, participant flow, or the statistical analysis plan. The allocation and masking classifications are explicit, but the operational details underlying them are not reported in the registry record. Those omissions limit the ability to assess how closely reported outcomes correspond to the intended study procedures.
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: Subject's eligibility was determined at the preoperative visit. All subjects met inclusion/exclusion criteria.
Overall Study
| Stage | AcrySof Toric IOL |
|---|---|
| STARTED | 120 |
| COMPLETED | 117 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | AcrySof Toric IOL |
|---|---|
| Unilateral implantation | 3 |
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 | AcrySof Toric IOL |
|---|---|---|
| Participants analysed | 120 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 77 |
| Age, Categorical: >=65 years | Participants | 43 |
| Sex: Female, Male: Female | Participants | 79 |
| Sex: Female, Male: Male | Participants | 41 |
6. Primary Endpoint
The registry lists the primary outcome as Visual Acuity (VA), measured over Pre-operative, 1 month, 3 month, and 6 month post-operative.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | logMAR |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is visual acuity, measured in logMAR. The registry describes it as a continuous measure and specifies that it is summarized by the mean and standard deviation. It lists assessments before surgery and at 1 month, 3 month, and 6 month post-operative. The summary explains that logMAR is the logarithm of the minimum angle of resolution and is a unit for visual acuity. In general, lower logMAR values correspond to better visual acuity.
Visual acuity is used to describe the clarity of vision under the assessment conditions. Measuring it at more than one time point can describe the course of the recorded outcome after implantation, rather than only a single postoperative observation. The pre-operative assessment also gives a baseline point for describing subsequent measurements. However, the registry record does not report the actual means, standard deviations, changes from baseline, or comparisons between assessment times. It is therefore not possible to characterize the direction, size, or precision of any observed change from this record.
The endpoint is relevant to the study’s stated purpose, which concerns postoperative visual acuity and spectacle independence for distance vision. It is not identical to spectacle independence: visual acuity is a measured visual function outcome, whereas spectacle independence concerns whether spectacles are needed. The registry lists spectacle independence separately as a secondary outcome. The endpoint description also does not specify the exact testing procedure, assessor, eye-level or participant-level analysis, or rules for combining measurements. Those details are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive limitation is that the registry record identifies the primary outcome and its assessment schedule but gives no numerical visual acuity results. No mean, standard deviation, baseline-to-follow-up change, confidence interval, or statistical test result is reported. Consequently, the posted record does not establish the direction or magnitude of the observed visual acuity measurements, nor how precisely they were estimated. It is not possible to describe a numerical outcome effect using the available registry information.
The study’s single-group, non-randomized design also sets limits on what an outcome pattern could establish, even if numerical values were available. A sequence of measurements among participants receiving the lens could describe what happened during follow-up, but without a comparator it could not isolate the lens’s effect from other explanations. Changes over time can reflect the intervention, the natural course of recovery, measurement variation, or other influences. This is a general design consideration, not a claim that any particular influence occurred in this study.
The mean and standard deviation are the stated summary measures. The mean describes the average recorded acuity, while the standard deviation describes variation among measurements around that average. The standard deviation is not itself a measure of how precisely the mean is estimated. Precision is commonly conveyed with a confidence interval or another uncertainty measure, but none is reported for the primary outcome in the registry record. There is therefore no basis for judging whether any estimate would be narrow or broad.
The time points are pre-operative and at 1 month, 3 month, and 6 month post-operative. That schedule could support a description of outcome values at each listed assessment, if the values and analysis details were available. It does not establish that the same participants contributed data at every assessment, or how missing observations were handled. The record does not give counts contributing to each time point or clarify whether the analysis used one eye, both eyes, or a participant-level summary. Such details affect the interpretation of means and their uncertainty.
The registry also states that the study’s purpose included spectacle independence for distance vision and rotational stability, and lists those as secondary outcomes. Their numerical results are not reported in the record. The primary visual acuity outcome therefore cannot be treated as a complete account of all outcomes named in the study purpose. Nor can the absence of reported numerical results be interpreted as evidence that an outcome was unchanged or that no event occurred.
Overall, the record supports a description of the study question, design, intervention, and planned measurement schedule. It does not supply the results required for an estimate of visual acuity or for a judgment about statistical precision. The appropriate reading is that the numerical efficacy results are unavailable in the registry record, not that the intervention had a particular effect or had no effect.
9. Statistical Methods Explained
The registry describes the primary outcome as continuous, measured in logMAR, with the mean and standard deviation as the summary statistics. These choices have distinct roles. The mean gives the average observed value in the analyzed data. The standard deviation describes the spread of individual measurements around that average. A larger spread indicates more variation among observations, but does not by itself show whether the mean is estimated precisely. Precision depends on the amount and structure of the data as well as their variability, and is usually presented with an uncertainty interval or another measure. No such numerical primary-outcome results are reported in the registry record.
What does a mean in logMAR represent?
LogMAR is a scale for visual acuity; the registry defines it as the logarithm of the minimum angle of resolution. As a general interpretation, lower logMAR values correspond to better visual acuity. The scale is continuous, so calculating a mean can summarize the average of recorded values. That summary is most useful when accompanied by the measurement distribution, the number of observations contributing to it, and an uncertainty measure. The registry does not report these outcome details. It is therefore not possible to assess the observed distribution, identify unusual values, or judge the precision of a reported mean.
Why does the assessment schedule matter?
The listed schedule includes a pre-operative measurement and post-operative measurements at 1 month, 3 month, and 6 month. Repeated assessments can describe how an outcome varies over follow-up. They also raise analysis questions: whether measurements from the same participant are treated as related, what happens when an assessment is missing, and whether the reported comparison is against baseline or between post-operative times. The registry record does not report the statistical model or the exact comparisons used. Without those details and the results, the schedule alone cannot establish a treatment-related change or its uncertainty.
Repeated measurements from the same person are generally correlated rather than independent. General methods for repeated data account for that correlation when estimating changes and uncertainty. Treating correlated observations as independent can misstate precision. The registry gives no analysis description that would show how correlation was handled. The record also does not clarify how bilateral measurements were represented in the analysis, despite the study title referring to bilateral implantation. These are methodological questions, not evidence that a particular analysis was or was not appropriate.
What can a single-group design estimate?
A single-group study can summarize outcomes observed among participants who received the intervention. In general, it cannot separate an intervention effect from other causes of change without an appropriate comparison or other design features that support causal inference. Here, allocation is classified as non-randomized and the model as single-group. The registry does not identify a control group or report an adjusted causal analysis. Consequently, even a complete set of before-and-after values would need to be interpreted as observed change in this group, rather than automatically as the effect attributable to the device.
How should the planning assumptions be read?
The registry includes a description of planning illustrations based on the observed effect. It specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. It also distinguishes illustrations reported as participants per arm from those reported as total events for time-to-event outcomes. These assumptions describe a hypothetical planning exercise; they are not the trial’s design or evidence that the study had a particular probability of detecting an effect. The registry record does not report the resulting planning values or the numerical observed effect needed to interpret them. Such illustrations are planning aids, never observed power.
The two-arm equal-allocation assumption does not match the recorded single-group design. A planning illustration built on that assumption should not be read as a reconstruction of the study’s actual sample-size justification. The sample-size justification, protocol assumptions, and any interim analyses are not reported in the registry record. No conclusion about the trial’s design adequacy follows from the planning-assumption description alone.
More generally, a p-value, when reported, addresses compatibility between data and a statistical model under a null hypothesis; it does not measure the size or clinical importance of an effect. A confidence interval expresses uncertainty around an estimate under its assumptions. Neither can be interpreted for the primary endpoint because the registry does not report an estimate, interval, or test result. Statistical methods can clarify what results would mean, but they cannot replace the missing outcome values.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists three outcome measures, names visual acuity as the primary outcome, and identifies Spectacle Independence and IOL Rotation as secondary outcomes. It reports zero analyses. This does not establish which outcomes were measured, which were analyzed, or whether all planned results were entered. Numerical results for the primary and named secondary outcomes are not reported in the registry record.
When a study evaluates multiple outcomes or makes multiple statistical comparisons, the chance of at least one apparently unusual result can increase. General approaches to multiplicity include prespecifying a primary comparison, adjusting the interpretation of tests, or treating secondary findings as exploratory. The registry does not report a multiplicity strategy, a hierarchy among comparisons, or whether any adjustment was used. It would therefore be inappropriate to infer that the outcome tests were adjusted or unadjusted, or to interpret unreported results as having passed a particular threshold.
Missing-data handling is also not reported. The scheduled assessments do not tell readers how many observations were available at each time, why any measurements might be absent, or whether missing values were excluded, imputed, or handled with a model. No assumptions about missingness can be verified from the record. This matters because an analysis based only on available observations can be affected if the absence of measurements is related to the outcome or participant characteristics.
The registry does not describe the analysis population, such as whether it includes all enrolled participants or only those with particular assessments. Nor does it report participant flow, endpoint-specific denominators, or the unit of analysis for bilateral measurements. Those details are needed to understand who contributed to the reported estimates and how the data were structured. In their absence, neither the completeness nor the representativeness of any outcome analysis can be assessed from the registry record.
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 |
|---|---|---|---|
| AcrySof Toric IOL | 0 | 120 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| AcrySof Toric IOL | 1 of 120 |
Most frequent non-serious adverse event terms
| Event term | Organ system | AcrySof Toric IOL |
|---|---|---|
| Lens Repositioning | Surgical and medical procedures | 1 of 120 |
For the AcrySof Toric IOL group, the registry lists 120 at risk for serious adverse events and 0 affected. For other adverse events, it lists 120 at risk and 1 affected. The record lists no serious adverse-event terms. These are the counts entered in the registry; they should not be expanded into rates or interpreted as a complete account of all possible safety outcomes.
The distinction between serious and other adverse events is important: the entries are separate categories, not interchangeable measures. The registry does not provide event descriptions for the other-adverse-event count, timing, severity, relatedness to the device, or information about how events were collected. It also does not report the number of events per affected participant or the criteria used to assign seriousness. Those details are not reported in the registry record.
Deaths are not reported in the registry record. A zero count for affected participants in the serious-event entry does not establish that every kind of harm was absent, nor does the other-event entry alone establish a causal relationship with the intervention. The counts should be read as registry entries with limited context, rather than as a comprehensive safety assessment.
12. What the Result Does, and Does Not, Mean
The record establishes that a completed PHASE4, single-group, non-randomized study evaluated the AcrySof Toric intraocular lens, with visual acuity identified as the primary outcome. It specifies logMAR measurement and lists pre-operative and post-operative assessment times. It also identifies spectacle independence and IOL rotation as secondary outcomes. These details describe the research question and its measurement framework.
The registry does not report numerical results for visual acuity or the named secondary outcomes. There is no reported mean, standard deviation, estimate of change, confidence interval, or test result for the primary endpoint. Accordingly, the record does not show the magnitude or direction of observed visual acuity values, or the precision with which any effect was estimated. The absence of numerical results is not evidence of no change, no effect, or no difference.
The design further limits causal interpretation. In a single-group, non-randomized study without a listed comparator, changes after implantation cannot be separated from other possible influences on measured outcomes. This is a general limitation of the design, not a finding about what caused any particular observation in this study. The registry also does not report enough information about analysis populations, missing data, or the handling of bilateral measurements to assess those aspects of the evidence.
Therefore, the registry supports a description of what was studied and how the primary endpoint was defined, but not a conclusion about treatment benefit, lack of benefit, or comparative performance. The recorded adverse-event counts provide limited safety information and lack event-level context. A fuller interpretation would require numerical outcome results and the relevant analysis and follow-up details, none of which are reported in the registry record.
13. Why This Trial Matters Statistically
This study is statistically informative as an example of why a clearly named endpoint and assessment schedule are not enough to evaluate results. The registry identifies visual acuity as a continuous outcome, specifies logMAR, and states that the mean and standard deviation were the intended summary measures. It also lists the timing of assessments. Those details help readers understand what was to be measured, but without the numerical values they cannot judge the observed outcome or its precision.
The design makes the distinction between description and causal inference especially important. A single-group study can characterize outcomes among people receiving an intervention, but it does not supply a concurrent comparison for separating the intervention’s contribution from other explanations. The non-randomized classification reinforces the need to avoid treating a before-and-after pattern, if one were reported, as an isolated treatment effect. The registry’s planning assumptions for a hypothetical two-arm comparison should likewise not be confused with the study’s actual design.
The record also illustrates how secondary outcomes, repeated assessments, missing-data methods, and analysis populations shape interpretation. Spectacle independence and IOL rotation are named, but their results and the multiplicity strategy are not reported. Follow-up times are listed, but the contribution of participants at each time and the treatment of repeated or bilateral measurements are not described. These are not minor technical details: they influence what an estimate represents and how much confidence readers can place in its precision.
The statistical lesson is not that the intervention had a favorable or unfavorable effect. Rather, the registry record supplies a framework for the question but lacks the numerical evidence required to answer it. Keeping that distinction clear prevents study design information from being mistaken for outcome evidence.
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.
Several limitations specific to this record restrict interpretation. It does not report primary visual acuity means or standard deviations at the listed assessment times, or any estimate of change. It also gives no confidence interval, test result, or other numerical measure of uncertainty. Thus, neither the outcome pattern nor its precision can be evaluated from the registry record.
The study is classified as single-group and non-randomized, and no comparator is identified. This prevents a direct comparison with another treatment or control condition and limits causal interpretation of any postoperative change. The record does not describe participant eligibility, baseline characteristics, recruitment, or participant flow, so the characteristics of the analyzed population and its relationship to the enrolled population are unclear.
The registry does not explain whether acuity was analyzed at the participant or eye level, how bilateral implantation measurements were combined, or how within-participant correlation was addressed. It also does not report endpoint-specific denominators, missing-data methods, or the analysis population. These omissions make it difficult to assess data completeness and the validity of any estimate. A statistical analysis plan, protocol, sample-size justification, interim analyses, and multiplicity approach are not reported in the registry record.
The secondary outcomes are named but their results are not reported. Safety entries lack event descriptions and other context, and deaths are not reported in the registry record. These gaps mean the record cannot support a comprehensive assessment of either efficacy outcomes or safety. The limitations reflect what is documented in the registry and should not be taken to establish what was or was not done outside it.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Visual Function After Implantation of Bilateral AcrySof® Toric Natural Intraocular Lens — NCT00760487.
- Registry record last updated 2012-01-16; status last verified 2012-01.
- Results first posted 2010-04-07.
- 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 registry record for NCT00760487 describes a completed PHASE4 study sponsored by Alcon Research, with enrollment listed as 120 and dates of 2006-10 to 2008-06 for study start and primary completion. It concerns cataract and the AcrySof Toric intraocular lens; the title specifies bilateral implantation.
The design is single-group, non-randomized, and unmasked. The primary outcome is mean visual acuity in logMAR, with standard deviation, assessed pre-operatively and at 1 month, 3 month, and 6 month post-operative. Spectacle Independence and IOL Rotation are listed as secondary outcomes. Numerical outcome results and the statistical analysis details needed to interpret them are not reported in the registry record.