Patient Perception of Visual Quality and Function: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Patient Perception of Visual Quality and Function (NCT02146599), a registered phase not stated study. The primary outcome is Use of Corrective Visual Aids (i.e., Spectacles, Contact Lenses) Post Intraocular Lens (IOL) Surgery.

2. Clinical Question

In plain terms, the record describes a patient self-assessment study focused on visual function and reliance on corrective aids after surgery. Its primary endpoint is a count of participants requiring visual aids, not a measure of visual acuity or a direct comparison of treatment effects. The record does not state a control group, random assignment, or a causal question comparing alternative approaches. It also does not report an estimate of how use changed between the scheduled visits. Thus, the question that can be answered from the posted endpoint data is limited: how many participants in the stated analysis population were reported as requiring corrective visual aids. The record does not establish whether that requirement was new, persisted from baseline, or changed over the follow-up interval.

3. Trial Design

The study is titled “Patient Perception of Visual Quality and Function” and lists cataract as its condition. The stated purpose is to evaluate visual quality and function in pseudophakic patients. The registry lists Abbott Medical Optics as sponsor, an enrollment of 301, a start date of 2014-05, a primary completion date of 2014-07, and a status of COMPLETED.

The listed intervention is administration of patient self-assessment. The record names a pseudophakic group, but does not describe a randomized allocation or a separate control group. Allocation is not stated. The record therefore does not support interpreting the listed lens-type categories as randomized arms or treating differences between them as effects caused by lens type. The registry record does not report a protocol explaining how participants entered those categories or how the study handled any differences between them.

The primary outcome is use of corrective visual aids, including spectacles and contact lenses, after intraocular lens surgery. The outcome description specifies a baseline visit and another visit one week later. In the result description, the analysis population is 295 participants with data, including monofocal participants, n=138; accommodating participants, n=34; and multifocal participants, n=123. The registry reports that 88 participants required corrective visual aids. It does not give separate counts at the two visits or a change score.

The record lists one outcome measure and no analyses. It does not report a statistical analysis plan, a sample-size justification, the intended handling of missing data, or any interim analyses. Those details are not reported in the registry record, so the design description is necessarily limited to the stated purpose, assessment activity, endpoint timing, and posted counts. A completed status indicates the registry’s recorded study status; by itself, it does not establish that all planned analyses or all possible results are available.

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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Of the 295 participants who provided data for this analysis (monofocal participants , n=138; accommodating participants, n=34; and multifocal participants, n=123), corrective visual aids (i.e., spectacles, contact lenses) post intraocular lens (IOL) surgery were required by 88 participants.

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 Use of Corrective Visual Aids (i.e., Spectacles, Contact Lenses) Post Intraocular Lens (IOL) Surgery, measured over Baseline and 1 week.

The primary endpoint is the number of participants reported as requiring corrective visual aids after intraocular lens surgery. The aids named in the registry are spectacles and contact lenses. The outcome is expressed as participants, and its parameter is NUMBER. In this setting, the reported value of 88 is a count of participants meeting the stated requirement, among the analysis population described in the record.

Use of corrective aids is a functional outcome: it records whether participants still require visual assistance in everyday vision after surgery. It can complement assessments focused on clinical measurements by capturing a practical aspect of visual function. This is a general explanation of why such an endpoint may be used; the registry does not state the investigators’ specific rationale for selecting it.

The timeframe is baseline and one week. That timing could support a comparison of status across visits if visit-specific observations and an appropriate analysis were reported. However, the registry gives a single count and does not provide separate baseline and one-week values, paired participant-level transitions, or a change estimate. The posted count therefore does not show how use changed over time. It also does not describe the frequency of use, the type of aid required by each participant, or the degree of visual difficulty. Those details are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is binary at the participant level: a participant either is or is not counted as requiring corrective visual aids under the endpoint definition. The registry reports the number with the stated outcome, rather than a continuous measurement such as a score. This kind of result is often summarized with a count and a denominator. The registry gives a count of 88 and describes an analysis population of 295 participants, but does not report a visit-specific breakdown or a statistical comparison.

What does a count tell us?

A count communicates how many participants met an outcome definition in a stated population. It does not, by itself, show how common the outcome is in a broader population, how uncertain the estimate is, or whether the outcome changed between assessments. Those questions generally require the relevant denominator, a defined assessment time, and an inferential method suited to the data. The record gives the analysis population and count, but does not provide an inferential result for the primary endpoint.

In general, binary outcomes can be analyzed using methods that compare the probability of an outcome between groups or time points. Which method is suitable depends on the design. For repeated observations from the same participants, an analysis should account for the pairing; treating observations as independent could misrepresent the uncertainty. For independent groups, the analysis structure differs. The registry record does not report an analysis method, and the single posted count does not allow a paired change analysis to be reconstructed.

How should uncertainty be understood?

In general, a confidence interval describes a range of values compatible with the observed data under the assumptions of a specified statistical method. It helps readers assess precision: a wider interval indicates more uncertainty about the estimate, while a narrower interval indicates greater precision under that method. A confidence interval is not reported for this outcome in the registry record. There is therefore no posted interval from which to assess the statistical precision of the count or any change over time.

A p-value, in general, quantifies how unusual data at least as extreme as those observed would be under a specified null hypothesis and statistical model. It does not measure the size or practical importance of an effect, and it cannot substitute for a clearly defined comparison. No p-value or hypothesis test is reported for the primary endpoint. Because no comparison result is posted, the count should not be described as statistically significant or not statistically significant.

What is needed to assess change?

The endpoint schedule mentions baseline and one week, but a change analysis would need results tied to each visit, and ideally information about how the same participants’ responses relate across visits. A transition summary could distinguish participants who required aids at both assessments from those whose status differed. The registry reports neither visit-specific totals nor participant-level transitions. It is therefore not possible to determine the direction, size, or precision of a change from the posted count alone.

General statistical practice also distinguishes a prespecified analysis from an exploratory one. A protocol or statistical plan can identify the primary contrast, define the endpoint at each time point, specify the analysis population, and explain how missing observations will be handled. None of those details is reported in the registry record. The record lists one outcome measure and no analyses, but does not explain whether analyses were conducted elsewhere or what methods were planned.

Why does the study structure matter?

Statistical interpretation depends on how participants were assigned and how groups were formed. Random allocation, when used and properly implemented, can support causal comparisons because it is intended to balance prognostic factors on average. The record does not state an allocation method and lists a pseudophakic group, rather than a stated randomized control comparison. The monofocal, accommodating, and multifocal categories appear in the description of the analysis population. The record does not identify them as randomized arms. Comparing their outcomes without further design information could reflect differences in who was included in each category, rather than an effect of category membership.

General statistical methods for binary outcomes may also need to account for clustering or repeated measurements when the design creates dependent observations. Over-dispersion is a general concern when observed variability exceeds what a simple model assumes; if ignored, standard errors and confidence intervals can be misleading. These are general concepts, not claims that either issue occurred in this study. The registry record does not report models, standard errors, or diagnostic checks, so it is not possible to determine which methods were used or whether these considerations applied.

Any sample-size illustrations are planning tools, not observed power. The stated planning assumptions refer to a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect expressed as a fraction of the observed effect. The registry does not report a randomized two-arm comparison or a primary-effect estimate in the posted results. Those planning assumptions should not be mistaken for the study’s own design rationale or for evidence that the study had a particular probability of detecting an effect. The sample-size justification is not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

Multiplicity concerns arise when several outcomes, time points, subgroups, or hypotheses are tested. In general, conducting many tests can increase the chance of at least one apparently notable result by chance, so a statistical plan may identify a primary outcome and explain any adjustment or hierarchy. The registry lists one outcome measure, but that fact alone does not establish how many hypotheses were tested or whether any multiplicity procedure was used. Adjustment methods and a full analysis plan are not reported in the registry record.

The primary outcome is scheduled at baseline and one week, yet the posted result does not give separate values by visit. It is therefore not possible to tell whether the registry intended a change comparison, a single-visit description, or another summary. No analysis of the repeated assessments is reported. The record also does not report subgroup-specific endpoint counts for monofocal, accommodating, or multifocal participants.

The enrollment is 301, and the primary outcome description identifies 295 participants with data for the analysis. The reasons that data are unavailable for some enrolled participants, the timing of any missingness, and the handling of missing observations are not reported in the registry record. Missingness can affect interpretation if participants without outcome data differ systematically from those included; this is a general concern, not evidence that such a difference occurred in this study.

The analysis population is described by the outcome record, but the registry does not state a formal intention-to-treat, per-protocol, or other analysis-population definition. It does not explain exclusions, eligibility for the endpoint analysis, or whether all participants were assessed at both visits. Without those details, the count should be attributed to the stated population with data, not assumed to represent all enrolled participants. The registry’s listing of no analyses also means that no multiplicity-adjusted or missing-data analysis can be evaluated from its posted results.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The registry lists the pseudophakic group with 296 participants at risk for serious adverse events and zero serious adverse events. It also lists 296 at risk for other adverse events and zero other adverse events. These are the posted safety counts for the listed group. The record does not provide event terms among the most frequent serious events.

These figures are descriptive counts. The registry record does not provide further detail about the safety observation period, event definitions, severity grading, attribution, or how events were collected. It therefore does not support conclusions about comparative safety, nor does a zero count establish that an event could not occur. The safety population at risk is listed separately from the primary endpoint analysis population, and the record does not explain that difference.

The deaths value is not reported in the registry record. A missing value should not be read as a reported zero. The safety counts also do not establish whether events were related to surgery, the intraocular lens, or study participation; attribution is not reported in the registry record.

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

The primary result establishes that the registry reports 88 participants as requiring corrective visual aids among the 295 participants described as having data for the analysis. This is a descriptive statement about the posted analysis population. The study’s stated objective concerns visual quality and function in pseudophakic patients, and the endpoint captures a practical aspect of visual aid use after intraocular lens surgery.

The result does not show how aid use changed from baseline to the visit one week later. Although both visits are named in the outcome timeframe, the registry does not separate the count by visit or describe which participants changed status. It also does not give counts for each lens-type category. The posted data therefore cannot establish whether one category had more or less aid use than another, or whether any category experienced a change over time.

The record does not report a comparator group, allocation method, statistical model, confidence interval, or p-value for the primary outcome. It does not support a causal claim about the effect of surgery, a particular lens type, or self-assessment. Nor does the count alone describe visual acuity, satisfaction, degree of dependence on aids, or the reasons a participant required them. Those outcomes and explanations are not reported in the registry record.

In general, a result can be statistically precise but clinically limited, or clinically relevant but uncertain; both the estimate and its uncertainty matter. Here, no interval or comparison estimate is reported, so precision for a change or contrast cannot be assessed. The reported count remains a useful descriptive record, but its scope should not be expanded beyond the participants and outcome definition named in the registry.

The completed status and enrollment describe the study record, not the completeness of every result. The posted information does not explain the difference between enrollment and the endpoint analysis population, and does not state how unavailable outcome data were addressed. These omissions limit interpretation and generalization. They do not invalidate the reported count, but they define what can reasonably be concluded from it.

13. Why This Trial Matters Statistically

This study illustrates the distinction between an outcome’s schedule and its reported analysis. The primary endpoint names baseline and a visit one week later, which suggests that time is relevant to measurement. Yet the registry reports one participant count without separate visit values. Readers therefore need to distinguish a scheduled repeated assessment from an analyzed change over time. A time frame in an outcome description does not itself provide evidence of change.

The record also shows why denominators and analysis populations matter. Enrollment is listed as 301, while the endpoint result describes 295 participants with data. The safety record separately lists 296 at risk. Those figures refer to different registry descriptions, and the record does not explain their relationship. Keeping each population tied to its own outcome prevents accidental denominator substitution and unsupported assumptions about who contributed to each result.

Another statistical lesson is that categories are not automatically comparison groups. The outcome population includes monofocal, accommodating, and multifocal participants, but the registry does not identify these as randomized arms or report category-specific outcomes. A comparison would require appropriate data and a design-aware analysis. Without those, treating category labels as evidence of comparative benefit or harm would overstate what the record establishes.

Finally, descriptive counts and inferential results answer different questions. A count records how many participants met the outcome definition; an interval or model-based comparison would address uncertainty or differences under explicit assumptions. The registry reports the count but no analyses. This makes the record useful for understanding the endpoint and its observed summary, while also demonstrating why transparent reporting of time-specific data, analysis populations, missingness, and statistical methods is essential for a fuller interpretation.

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 registry record gives a limited account of the endpoint results. It reports the count of participants requiring corrective visual aids but does not identify separate baseline and one-week values. There is no transition information showing whether participants began, stopped, or continued using aids. This prevents assessment of the endpoint as a change over time, despite the two scheduled assessment visits.

The analysis population is identified as 295 participants with data, and the record lists enrollment as 301. Reasons for the difference and the handling of unavailable outcome data are not reported in the registry record. The lens-type categories are named, but no category-specific counts for the primary endpoint are given. The record also does not describe whether participants were assessed at both visits or how the endpoint was operationalized for an individual whose status differed between visits.

Design details are sparse. Allocation is not stated, and the record does not describe a like-for-like control comparison. It does not report a formal analysis population, statistical analysis plan, effect estimate, confidence interval, or p-value. Sample-size justification and interim analyses are not reported in the registry record. These absences limit evaluation of precision, bias, and the intended statistical interpretation; they should not be filled in by assumption.

The endpoint is a count of participants requiring corrective aids, but the record does not report the type of aid by participant, frequency of use, visual acuity, degree of difficulty, or patient-reported scale results. Although the study purpose refers to visual quality and function, the posted primary outcome does not capture every dimension of those concepts. No conclusions about outcomes not reported in the registry can be drawn from the corrective-aid count alone.

Safety reporting is also limited to aggregate counts. Definitions, observation period, attribution, and event details are not reported in the registry record. The listed safety population differs from the endpoint analysis population, with no explanation of the relationship. These limits counsel against broader comparative or causal interpretations of either efficacy-related or safety results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Patient Perception of Visual Quality and Function — NCT02146599.
• Registry record last updated 2015-09-28; status last verified 2015-09.
• Results first posted 2015-09-07.
• 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.

18. Record Summary

The registry record describes a completed study titled “Patient Perception of Visual Quality and Function,” sponsored by Abbott Medical Optics, with cataract listed as the condition. Enrollment is 301; the recorded start is 2014-05 and primary completion is 2014-07. The stated purpose is to evaluate visual quality and function in pseudophakic patients. The listed activity is administration of patient self-assessment.

The primary outcome measures the number of participants requiring corrective visual aids after intraocular lens surgery, with assessments scheduled at baseline and one week. The result description identifies 295 participants with data and reports that 88 required corrective aids. It names monofocal, accommodating, and multifocal participants, but does not report their separate endpoint results or visit-specific counts.

The registry lists one outcome measure and no analyses. Allocation, analysis methods, missing-data handling, and a sample-size justification are not reported in the registry record. Safety listings report zero serious adverse events and zero other adverse events among 296 at risk in the pseudophakic group; deaths are not reported. The posted results support a descriptive reading of the stated count, not a comparison or conclusion about change over time.