Surgeon Experience ReSTOR A +4 Intraocular Lens (IOL): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Surgeon Experience ReSTOR A +4 Intraocular Lens (IOL) (NCT00733512), a registered phase not stated study. The primary outcome is Visual Acuity.

2. Clinical Question

In practical terms, the record concerns how visual acuity was to be measured after lens implantation, not a comparative estimate of the lens against another intervention. Uncorrected visual acuity (UCVA) describes acuity without spectacle correction; best spectacle corrected visual acuity (BSCVA) describes acuity with the best spectacle correction. Distance testing is specified at 4 meters, while near testing is at the participant’s preferred distance. The registry identifies contrast sensitivity as a secondary outcome, but does not report its numerical results either.

The record gives an enrollment total and a broad measurement window, but does not say how many participants contributed data at each measurement, how results were summarized at particular visits, or which participant characteristics were used to define the analysis population. Those details are not reported in the registry record. The central question that can be addressed from the record is therefore descriptive: which visual acuity outcomes were selected and how were they defined? The magnitude and precision of any observed changes cannot be determined from the reported information.

3. Trial Design

The registry record identifies NCT00733512 as a completed study sponsored by Alcon Research. It lists cataract as the condition and ReSTOR as the device intervention. The record gives enrollment as 146 and lists the study start as 2007-06 and primary completion as 2008-03. The brief summary describes collecting visual outcome data after AcrySof ReSTOR Aspheric +4 implantation from surgeons throughout the United States.

The record does not describe a randomized comparison. Allocation is not stated, and a like-for-like control comparison is not identified. The listed arm description is the AcrySof ReSTOR Aspheric +4 intraocular lens. No comparator is reported in the registry record, so the study information does not support a treatment-versus-control interpretation. The record also does not report whether participants were assigned to any additional groups, or how surgeons or participants entered the study.

The primary outcome is visual acuity, reported as a mean with standard deviation in logMAR. The stated timeframe is one week to ten months. Its description includes UCVA and BSCVA for distance at 4 meters and near at preferred distance. Contrast sensitivity is listed as a secondary outcome. The registry reports two outcome measures, but does not provide numerical results or analyses for them.

The study is marked completed, but completion status alone does not establish that every planned measurement was collected or that results were analyzed. The number of analyses recorded is zero. Specific details about follow-up schedules, visit windows, blinding, eligibility criteria, recruitment, handling of deviations, or the statistical plan are not reported in the registry record. Those omissions limit how fully the conduct and analysis can be reconstructed.

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: Subjects eligibility was determined at the preoperative visit.

Overall Study

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.

6. Primary Endpoint

The registry lists the primary outcome as Visual Acuity, measured over 1 week to 10 months.

The primary endpoint is visual acuity expressed in logMAR, with the registry describing the reported quantity as a mean and its dispersion as a standard deviation. The outcome definition includes uncorrected visual acuity and best spectacle corrected visual acuity, measured at distance and near. Distance is specified as 4 meters; near is measured at the preferred distance. The stated timeframe ranges from one week to ten months.

Visual acuity is a direct measure of the visual function the study set out to document after implantation. UCVA records acuity without spectacle correction, while BSCVA records acuity with best spectacle correction. Considering both helps distinguish measured acuity without correction from acuity under spectacle correction. The distance and near settings capture different viewing tasks. These are general reasons such measures can be useful; the registry does not report a particular rationale for selecting these exact endpoint components.

LogMAR is described in the record as the logarithm of the minimum angle of resolution. The record states that a lower logMAR value indicates better visual acuity. Reporting a mean gives a summary of the measured values, while the standard deviation describes their spread around the mean. Neither summary is available as a numerical result in the registry record. The record also does not clarify whether results were intended to be reported separately for each correction condition, distance, visit, or participant subgroup.

Because the measurement window spans multiple months, interpretation would depend on knowing when each observation was taken and how measurements across visits were handled. Those details are not reported in the registry record. The endpoint definition indicates what was measured, but does not by itself provide evidence about the size, consistency, or precision of the observed visual acuity results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean and standard deviation describe?

For a continuous measure such as logMAR visual acuity, a mean is a summary of the observed values. The standard deviation describes how dispersed those values are around the mean. These quantities answer different questions: the mean locates the center of the data, while the standard deviation describes variability among measurements. A standard deviation is not the uncertainty in the mean; uncertainty in an estimated mean is commonly conveyed with a confidence interval. These are general statistical explanations. The registry identifies the mean and standard deviation as the intended summary, but does not report their numerical values.

The mean can be useful for summarizing a group, but it does not show the full distribution. Different distributions can share the same mean and standard deviation. For that reason, interpretation can also depend on the shape and spread of the observed values, whether there are unusual observations, and how many measurements contributed. Those details are not reported in the registry record. The outcome is described across multiple correction conditions and testing distances, so a reader would also need to know how those components were presented and analyzed. That information is not reported.

How should logMAR be read?

The registry defines logMAR as the logarithm of the minimum angle of resolution and states that a lower value indicates better visual acuity. This direction matters when reading any estimate: a lower reported logMAR value corresponds to better acuity under the stated definition. However, the direction alone does not establish what the study observed. The numerical results are not reported in the registry record, and no change or contrast between conditions can be described.

UCVA and BSCVA are distinct measurement conditions. UCVA is uncorrected visual acuity; BSCVA is best spectacle corrected visual acuity. Distance is tested at 4 meters, while near testing uses preferred distance. These distinctions describe what the outcome covers, but they do not specify whether the registry intended separate estimates for each combination, a selected primary comparison, or a repeated-measures analysis. The analysis method for these components is not reported in the registry record.

What does a confidence interval add?

In general, a confidence interval expresses uncertainty around an estimate under a statistical model and its assumptions. A narrow interval indicates greater precision than a wider interval, all else equal. It is not a guarantee that the true value lies within the interval, nor does it resolve design limitations such as the absence of a comparator. The registry record does not provide confidence intervals, standard errors, or numerical estimates, so precision cannot be evaluated for the primary outcome.

A p-value, when reported, addresses how compatible the observed data are with a specified null model under the analysis assumptions. It is not a measure of clinical importance or the probability that a hypothesis is true. No p-values or inferential analyses are reported in the registry record. The analysis count is zero; the record does not identify a test or model to interpret.

Why does the comparison structure matter?

Statistical interpretation depends on the study question and design. A single intervention description without a reported comparator does not provide a direct randomized between-group estimate. The record explicitly does not describe a randomized comparison, and allocation is not stated. This prevents interpreting the record as a randomized efficacy comparison. A before-and-after contrast, if one had been planned, would require defined time points and a method for handling repeated measurements; neither is reported in the registry record. No such contrast should be inferred from the broad timeframe alone.

The registry lists a timeframe from one week to ten months. In general, repeated measurements on the same participant are correlated, so analysis methods may need to account for within-participant dependence. Treating correlated measurements as independent can misstate uncertainty. This is a general methodological point; the record does not say whether measurements were repeated, how they were grouped, or what model was used. It therefore does not support an assessment of those choices.

What are the planning calculations?

The record characterizes the sample-size illustrations as planning calculations based on the observed effect, not the trial’s own design. Their stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. Such calculations are prospective illustrations of how a hypothetical design might perform under assumptions. They are not observed power, do not show that the trial used an equal allocation, and do not substitute for reported outcome estimates.

Because the numerical observed effect and numerical planning results are not reported in this record, the calculations cannot be interpreted as a quantitative assessment. The record also does not report the trial’s own sample-size justification. In general, power calculations depend on assumptions about the target effect, variability, significance level, allocation, and analysis. If assumptions differ from the actual study, the planning result may not describe the study’s precision or ability to detect an effect.

For continuous outcomes, over-dispersion means variability is greater than assumed by a model. In general, if actual variability exceeds the planning assumption, estimates may be less precise than anticipated. The registry does not report a variability assumption for study planning or an analysis model, so no claim can be made about whether over-dispersion was assessed. This illustrates why a planning calculation must be read as conditional on its assumptions rather than as a result of the completed study.

What cannot be reconstructed?

The registry does not report the statistical analysis plan, the analysis population, the number of participants with outcome data, the handling of missing measurements, or whether any interim analyses were conducted. These details are not reported in the registry record. Without them, it is not possible to reproduce an analysis or judge whether the reported endpoint was analyzed as planned. The zero analyses entry and absence of numerical outcome results also mean that no estimate can be checked against an independent recalculation.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists visual acuity as the primary outcome and contrast sensitivity as a secondary outcome. The visual acuity definition itself includes UCVA and BSCVA, distance and near testing, and a measurement window from one week to ten months. The record reports two outcome measures, but does not explain how many separate statistical comparisons, time points, or outcome components were analyzed. It records zero analyses, and numerical results are not reported in the registry record.

Multiplicity is a general concern when several outcomes, visits, or comparisons are tested: the more tests considered, the greater the chance that at least one result may appear noteworthy by chance if no adjustment or prespecified hierarchy is used. Whether adjustment is appropriate depends on the aims and analysis plan. The registry record does not report a multiplicity strategy, a hierarchy among visual acuity components, or a plan for handling several time points. It is therefore not possible to determine how multiplicity was addressed.

Missing-data handling is also not reported. The enrollment total does not establish how many participants had measurements at each visit or contributed to each outcome. The registry does not state whether missingness occurred, why data might be missing, or whether any imputation or other method was used. These details are not reported in the registry record. In general, conclusions can depend on how incomplete observations are handled, particularly when missingness is related to the outcome or participant characteristics.

The analysis populations are not described. The registry does not specify whether analyses were intended to include all enrolled participants, only those with available measurements, or another defined group. The outcome population field is blank. No assumptions about analysis populations or missing-data procedures can therefore be made from the record.

11. What the Result Does, and Does Not, Mean

The record establishes that a completed study enrolled 146 participants and planned to collect visual outcome data after implantation of the AcrySof ReSTOR Aspheric +4 intraocular lens. It defines the primary outcome as mean visual acuity in logMAR, with standard deviation, and describes UCVA and BSCVA at distance and near over a timeframe from one week to ten months. It also lists contrast sensitivity as a secondary outcome. These details clarify the subject and measurement framework of the study.

They do not establish the observed visual acuity values. The numerical primary and secondary results are not reported in the registry record. There are no reported estimates, confidence intervals, p-values, or analysis results from which to judge the size or precision of any observed outcome. The fact that lower logMAR indicates better acuity explains how a value would be oriented, but does not reveal what values were observed.

The record also does not support a comparative claim about the lens. It does not describe a randomized comparison, allocation is not stated, and no comparator is reported. Without a reported comparison and analysis, the information cannot quantify how outcomes differed from another intervention or from an appropriate control condition. The study summary describes collection of outcomes after implantation; it does not, by itself, establish that any observed outcome was caused by the intervention.

Likewise, the adverse-event entries should be interpreted cautiously. The ReSTOR group has zero listed at risk and zero listed affected, and the death count is not reported in the registry record. Zero at risk is not evidence that no adverse events occurred among an evaluated population. No serious-event terms are listed, but the record does not provide an interpretable safety analysis from which to estimate event frequency.

The planning illustrations are not outcomes and are not evidence of observed power. Their assumptions describe a hypothetical calculation, not the trial’s actual design. In general, power is a prospective property of a specified design and assumptions, not a retrospective measure of whether a study produced a meaningful result. No result can be inferred from a planning illustration.

Accordingly, the registry record is informative about the outcome definitions and basic study description, but not about the magnitude, precision, comparative meaning, or safety profile of the results. Those conclusions require information that is not reported in the registry record.

12. Why This Trial Matters Statistically

This study is statistically notable because it makes clear how an outcome definition can be detailed while the evidence needed to interpret results remains unavailable. The record specifies logMAR, the mean and standard deviation, correction conditions, testing distances, and a broad timeframe. These elements help define what was intended to be measured. Yet numerical outcomes and analyses are not reported in the registry record, so the measurement description cannot be converted into an estimate or conclusion.

The nonrandomized comparison status and absence of a described comparator are central to interpretation. Even complete outcome summaries would not automatically provide a causal contrast. Statistical methods can quantify uncertainty in an estimate, but they cannot create a valid comparison that the design does not describe. The record does not state allocation, making it especially important not to treat planning assumptions about equal allocation as a description of the actual study.

The outcome has several components: UCVA and BSCVA, distance and near, plus a measurement window extending from one week to ten months. In general, multiple components and time points raise questions about which outcomes were prespecified as primary, how repeated observations were modeled, and whether multiplicity was addressed. The registry record does not report those details. Recognizing these questions is useful even when no numerical analysis is available, because it separates the existence of a defined outcome from evidence about an effect.

The record also illustrates why enrollment and completion status do not alone communicate statistical certainty. Enrollment is reported, but the number analyzed for each measure, the variability of results, and the confidence intervals are not reported. A completed status does not tell readers whether all intended observations were available or how missing data were handled.

For clinical researchers, the lesson is methodological rather than clinical: transparent reporting of estimates, uncertainty, analysis populations, missing-data procedures, and comparison structure is necessary for readers to evaluate evidence. Here, the registry description identifies what the study sought to measure, but leaves those result-level questions unanswered.

13. 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 primary limitation is that numerical outcome results are not reported in the registry record. The record gives no visual acuity means or standard deviations, no contrast sensitivity results, and no inferential analyses. The analysis count is zero. Consequently, the size and precision of any observed outcomes cannot be assessed.

The registry does not describe a randomized comparison, gives no comparator, and does not state allocation. The record therefore does not provide a like-for-like control comparison from which to estimate a comparative effect. The intervention description names ReSTOR, but no further design details are reported that would permit reconstruction of how participants or measurements were organized.

Several elements of the primary endpoint remain unclear. The outcome covers UCVA and BSCVA at distance and near, with a timeframe from one week to ten months, but the registry does not report visit-specific estimates, the handling of repeated measurements, or whether the components were analyzed separately. The population field is blank. Participant characteristics, eligibility criteria, and the number contributing data to each outcome are not reported in the registry record.

The statistical plan, sample-size justification for the study itself, missing-data procedures, analysis populations, and multiplicity strategy are also not reported. The planning illustrations have stated assumptions, but are described as calculations rather than the trial’s own design. They cannot fill the gap left by absent outcome results or establish observed power.

Safety interpretation is limited as well. The record lists zero at risk and zero affected, which does not provide an evaluable denominator for event assessment. The death count is not reported in the registry record. Completion status and the absence of serious-event terms do not resolve these limitations. These specific gaps prevent a full statistical assessment of outcomes and safety from the registry information.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Surgeon Experience ReSTOR A +4 Intraocular Lens (IOL) — NCT00733512.
• Registry record last updated 2017-03-27; status last verified 2010-04.
• Results first posted 2010-04-15.
• 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.

17. Record Summary

NCT00733512 is listed as a completed study sponsored by Alcon Research, with cataract as the condition and ReSTOR as the device intervention. The brief summary describes collecting visual outcome data after AcrySof ReSTOR Aspheric +4 implantation from surgeons throughout the United States. Enrollment is reported as 146; the study start is 2007-06 and primary completion is 2008-03.

The primary outcome is visual acuity in logMAR, summarized as a mean with standard deviation over a timeframe of one week to ten months. The outcome definition includes UCVA and BSCVA at distance, specified as 4 meters, and near at preferred distance. Contrast sensitivity is listed as a secondary outcome.

The registry does not describe a randomized comparison, states no allocation, and reports no comparator. Numerical outcome results and analyses are not reported in the registry record; the analysis count is zero. The analysis plan, missing-data methods, analysis populations, and study-specific sample-size justification are also not reported. The record supports description of the study and its outcome definitions, but does not support estimation of outcome magnitude or precision.