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 Assessment of Low Energy Lens Fragmentation Cataract Extraction in Patients Undergoing Cataract Surgery (NCT04747834), a non-randomized na study. The primary outcome is Total Lens Removal Time.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04747834 |
| Phase | NA |
| Condition | Cataract |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 100 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Carl Zeiss Meditec, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns subjects undergoing routine cataract surgery. Cohort 1 is described as having mild to moderate cataracts (Grade 1 to 2); Cohort 2 is described as having moderate to dense cataracts (Grade 2+ to 3+). The registry record does not report further participant characteristics in the primary-outcome population.
Intervention
Both cohorts were scheduled for mechanical non-phacoemulsification lens extraction using low-energy segment removal with the micro-interventional irrigation/aspiration port MICOR-304. The device is used to evacuate the lens before intraocular lens insertion.
Comparator
The registry record describes two cohorts organized by cataract grade, not a randomized treatment and control comparison. Both cohorts are scheduled to receive the MICOR-304 procedure. Because allocation was non-randomized, the cohorts should not be treated as like-for-like controls.
Primary question
The primary outcome is total lens removal time, measured in seconds during surgery. The record defines this as the time for nucleus removal followed by the time for cortex removal using irrigation and aspiration. It does not report cohort-specific values, confidence intervals, or an analysis comparing the cohorts.
The clinical question is therefore descriptive: what lens removal times and other clinical outcomes were recorded for subjects undergoing the stated procedure, and how were those outcomes characterized? The registry record identifies the intended procedure and outcome but does not provide the primary endpoint results. It also does not report an estimate of the difference between cataract-grade cohorts. Even if cohort-level results were available, a contrast between these non-randomized groups would not by itself isolate an effect of cataract grade or of the device; the groups differ by their stated cataract severity and were not assigned through randomization.
3. Trial Design
This is a prospective, multicenter study of a device used in cataract surgery. The registry record lists the study as completed, with a start date of 2021-01-06 and primary completion date of 2022-01-24. Enrollment is listed as 100. The phase is recorded as NA. The sponsor is Carl Zeiss Meditec, Inc.
Allocation is non-randomized, masking is none, and the model is parallel. The study describes two cohorts rather than a randomized comparison. Cohort 1 includes subjects with mild to moderate cataracts (Grade 1 to 2), while Cohort 2 includes subjects with moderate to dense cataracts (Grade 2+ to 3+). Both cohorts are scheduled to undergo mechanical non-phacoemulsification lens extraction using low-energy segment removal with MICOR-304, followed by intraocular lens insertion.
The primary outcome is total lens removal time. Listed secondary outcomes include total surgical procedure time, visual acuity measures at specified follow-up times, change in corneal thickness, and corneal edema measures. The registry record lists 39 outcome measures and 0 analyses. It does not report the numerical results for the primary outcome or describe analyses of the secondary outcomes.
Non-randomized allocation matters to interpretation: differences between cohorts could reflect differences in cataract severity or other characteristics, rather than a causal effect of the procedure. The record does not describe a separate control group receiving another procedure. It also does not report details of masking beyond the designation of none, or the statistical analysis plan.
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
| Stage | Cohort 1 | Cohort 2 |
|---|---|---|
| STARTED | 44 | 56 |
| COMPLETED | 44 | 56 |
| NOT COMPLETED | 0 | 0 |
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 | Cohort 1 | Cohort 2 | Total |
|---|---|---|---|---|
| Participants analysed | 44 | 56 | 100 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 20 | 9 | 29 |
| Age, Categorical: >=65 years | Participants | 24 | 47 | 71 |
| Age, Continuous | years | 66.3 (SD 6.6) | 70.2 (SD 6.2) | 68.5 (SD 6.7) |
| Sex: Female, Male: Female | Participants | 26 | 30 | 56 |
| Sex: Female, Male: Male | Participants | 18 | 26 | 44 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 1 | 0 | 1 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 43 | 54 | 97 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 2 | 2 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 7 | 1 | 8 |
| Race (NIH/OMB): White | Participants | 36 | 53 | 89 |
| Race (NIH/OMB): More than one race | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 2 | 2 |
| Region of Enrollment: United States | participants | 44 | 56 | 100 |
6. Primary Endpoint
The registry lists the primary outcome as Total Lens Removal Time, measured over Assessed during the surgical procedure, measured in seconds..
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | seconds |
| Endpoint classification | Continuous Endpoint |
Total lens removal time is the primary endpoint. The registry record defines it as the combined duration of two procedural phases. The first begins when the surgeon enters the eye with MICOR-304 to start lens removal and ends when nucleus removal with MICOR-304 is complete, before switching to irrigation and aspiration. The second begins when the irrigation and aspiration tip enters the eye and ends when cortex removal is complete. The endpoint is listed in seconds; the description also says that the time is recorded in minutes and seconds.
As a continuous measure, time can describe how long the specified lens-removal tasks take. A mean gives a summary of the recorded times, while a confidence interval can communicate the uncertainty around an estimated mean. The registry record lists the mean and a 95% confidence interval as the intended summary. It does not report the cohort means, confidence intervals, the number of observations used in the endpoint analysis, or a comparison between cohorts.
Timing a defined procedural process can support a quantitative description of the procedure. It does not, on its own, characterize visual outcomes, complications, or the overall clinical experience. Those require consideration of the other outcomes and their results, which are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clear primary outcome—total lens removal time—but does not report a mean, a 95% confidence interval, or any other numerical result for that outcome. Consequently, the posted record does not establish the typical recorded time, the precision of an estimate, or whether the cohorts differed in time. It is not possible to characterize the size or direction of any observed primary-outcome contrast from the information reported.
The record lists 39 outcome measures and 0 analyses. That distinction is important: outcome measures indicate what was registered for assessment, whereas analyses and numerical results are needed to evaluate what the study found. The list of secondary outcomes includes surgical duration, visual acuity at follow-up, corneal thickness, and corneal edema. Their names alone do not indicate the values observed, the completeness of follow-up, or the strength of evidence for any difference.
The two cohorts are defined by cataract severity and both are scheduled to undergo the MICOR-304 procedure. They are not randomized treatment and control groups. A difference between their outcomes, if reported, could reflect differences in cataract severity or other characteristics, as well as procedural factors. Without random assignment or a reported adjusted analysis, a cohort contrast should be read as an association rather than a causal estimate. The registry record does not report adjustment variables or an analysis that addresses potential confounding.
The safety listing reports serious adverse event counts of 0 for Cohort 1 and 1 for Cohort 2, with deaths listed as 0 in both cohorts. The record also lists other adverse event counts and a serious-event term, described separately in the safety interpretation. These counts are descriptive registry entries; the record does not provide enough detail to infer comparative safety, causality, or the clinical importance of individual events.
Planning illustrations based on an observed effect, if considered, are not evidence that an effect was detected or that the study had a particular probability of success. The registry record does not report a primary-outcome estimate on which to base an interpretation of the actual findings. Any such illustration is a planning calculation under its stated assumptions, not an observed power result.
Overall, the record supports a description of the intended study design, cohorts, endpoints, and certain adverse-event counts. It does not provide primary or secondary outcome analyses from which to assess the magnitude or precision of clinical outcomes. These omissions limit statistical interpretation; they do not establish that an outcome was favorable or unfavorable.
9. Statistical Methods Explained
What does a mean describe?
The primary endpoint is continuous: each recorded lens removal time is a duration. A mean is a summary of the observed times, expressed in the same measurement units. It describes the center of the recorded values, but does not show their full spread or reveal whether there are unusually short or long observations. Other summaries, such as the range or standard deviation, can add information about variability, but the registry record does not report those statistics for the primary endpoint.
The mean can be useful when the research question concerns average procedural duration. Its interpretation depends on how the endpoint was measured and which observations were included. The registry record defines the two phases contributing to total lens removal time, but does not report the number of endpoint observations, the handling of incomplete measurements, or whether the reported endpoint results were summarized separately by cohort.
How should a confidence interval be read?
A confidence interval communicates uncertainty around an estimate. In general, a narrower interval indicates greater precision under the assumptions of the analysis, while a wider interval indicates less precision. A 95% confidence interval is a method-based interval, not a guarantee that a particular interval contains the true value. Its interpretation relies on the sampling and analysis assumptions being appropriate.
The primary outcome is registered with a 95% confidence interval, but no interval bounds or mean are reported in the registry record. The precision of the intended estimate therefore cannot be assessed. A confidence interval for a mean would describe uncertainty about that mean; it would not by itself account for confounding between non-randomized cohorts or establish a causal effect.
Why does the allocation matter?
Random allocation, in general, is used to make assigned groups comparable on average with respect to measured and unmeasured characteristics. This study is listed as non-randomized. Its cohorts are defined by cataract severity, and both receive the described procedure. A comparison between the cohorts would therefore not have the protection against confounding that random allocation can provide.
For a non-randomized comparison, differences in measured outcomes may be associated with group membership without being caused by it. Statistical adjustment can sometimes address measured differences, but it cannot automatically resolve unmeasured or poorly measured confounding. The registry record does not report adjusted estimates, covariates, or a plan for handling confounding. Accordingly, a causal interpretation is not supported by the registered design details alone.
What do the analysis counts tell the reader?
The record lists 39 outcome measures and 0 analyses. This means the record identifies outcome measures but does not present an analysis count or numerical analysis results. The presence of an endpoint in the registry does not supply an estimate, a standard error, a confidence interval, or a test result. Without those details, readers cannot evaluate the magnitude, direction, or precision of the primary outcome.
The record specifies a mean and 95% confidence interval for the primary endpoint. It does not state whether a statistical test was planned, whether the primary estimate was to be pooled or reported by cohort, or how any comparison would be performed. These details are not reported in the registry record. No test statistic or p-value for the primary endpoint is reported.
What does over-dispersion mean in general?
For count outcomes, over-dispersion means that observed variability exceeds what a simple statistical model assumes. When present, it can make standard errors too small if the extra variability is ignored, leading to confidence intervals that are too narrow and tests that appear more conclusive than warranted. This is a general statistical consideration, not a reported feature of this study. The registry record does not identify an over-dispersed outcome model or report model diagnostics.
The primary endpoint is a continuous duration, so count-model over-dispersion is not itself a description of this endpoint. General issues for time measurements include skewness, outlying observations, and unequal variability across groups. Those properties can affect whether a mean and its interval are well summarized by a chosen method. The registry record does not report distributions or diagnostic checks for the time measurements, and no particular problem should be inferred.
How should planning illustrations be understood?
In general, sample-size planning asks how much information a future study would need to detect a specified effect under stated assumptions. The registry record describes planning illustrations based on a fraction of an observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation. The record distinguishes participant counts per arm for most outcomes from total event counts for time-to-event outcomes. These are planning conventions, not observed study findings.
A planning illustration based on an observed effect does not show that the effect is clinically important, reliable, or causal. It also is not observed power. Since the registry record does not report the primary outcome estimate, its precision, or the details of an analysis, the primary findings cannot be assessed from the registered material. The assumptions described for planning do not substitute for a reported statistical analysis plan.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists a broad set of outcome measures: 39 in total, including the primary endpoint and secondary measures. When many outcomes or repeated assessments are examined, the chance of at least one apparently notable result can increase. In general, a study can address this by prespecifying a hierarchy of outcomes, adjusting for multiple comparisons, or clearly distinguishing confirmatory from exploratory analyses. The registry record does not report a multiplicity strategy, a testing hierarchy, or which outcomes were treated as confirmatory.
The listed secondary outcomes include total surgical procedure time, visual acuity at 1-Day, BCDVA at 1 Week and 1 Month, change in corneal thickness, and corneal edema measures. The record does not provide numerical results or analyses for these outcomes. It therefore is not possible to determine which measures were analyzed, whether repeated assessments were handled together, or whether any multiplicity adjustment was applied.
Missing-data methods and analysis populations are also not reported in the registry record. The record does not describe how incomplete visits, missing endpoint times, withdrawals, or other unavailable measurements were handled. It does not specify whether analyses used all enrolled subjects, only subjects with observed outcome data, or another defined population. Without those details, the potential effect of missing data on estimates cannot be evaluated.
The registry record does not report an interim-analysis plan or a statistical analysis plan. No conclusion about these procedures should be inferred from their absence. The listed 0 analyses means no analysis results are presented in the registry record; it does not by itself establish what analyses may have been conducted outside the 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 |
|---|---|---|---|
| Cohort 1 | 0 | 44 | 0.0% |
| Cohort 2 | 1 | 56 | 1.8% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Cohort 1 | 0 of 44 |
| Cohort 2 | 0 of 56 |
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 |
|---|---|
| Cohort 1 | 10 of 44 |
| Cohort 2 | 13 of 56 |
Most frequent serious adverse event terms
| Event term | Organ system | Cohort 1 | Cohort 2 |
|---|---|---|---|
| Pneumonia | Immune system disorders | 0 of 44 | 1 of 56 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Cohort 1 | Cohort 2 |
|---|---|---|---|
| Study Eye - Raised IOP Requiring Treatment | Eye disorders | 5 of 44 | 7 of 56 |
| Study Eye - Dry Eye | Eye disorders | 1 of 44 | 1 of 56 |
| Study Eye - Corneal Edema | Eye disorders | 0 of 44 | 2 of 56 |
| Study Eye - Posterior Capsule Rupture | Eye disorders | 1 of 44 | 0 of 56 |
| Study Eye -Vitreal Prolapse | Eye disorders | 1 of 44 | 0 of 56 |
| Study Eye - Cystoid Macular Edema | Eye disorders | 1 of 44 | 0 of 56 |
| Study Eye - Increased Inflammation | Eye disorders | 1 of 44 | 0 of 56 |
| Study Eye - Ectropion | Eye disorders | 1 of 44 | 0 of 56 |
| Study Eye - Crocodile Shagreen | Eye disorders | 0 of 44 | 1 of 56 |
| Study Eye - Microcystic Corneal Edema | Eye disorders | 0 of 44 | 1 of 56 |
Serious events with the highest arm-level rate: pneumonia (1.8%).
The adverse-event listing gives cohort-specific counts and risk-set denominators. For Cohort 1, 44 are listed as at risk for serious adverse events and 0 as affected; 44 are listed as at risk for other adverse events and 10 as affected. For Cohort 2, 56 are listed as at risk for serious adverse events and 1 as affected; 56 are listed as at risk for other adverse events and 13 as affected. Deaths are listed as 0 in each cohort.
The registry record lists Pneumonia at 1.8% among the top serious adverse event terms. It does not identify a cohort for that term in the listed entry, so the term should not be assigned to a cohort based on the other counts. The entry does not explain the event’s timing, severity details, relatedness to the device or procedure, or whether the term represents a participant-level count.
These figures are descriptive entries, not a randomized comparison. The cohorts differ in their stated cataract severity, and the study is non-randomized. The counts should not be interpreted as proving that the procedure caused or prevented an event, or as establishing a comparative safety difference. The registry record does not report further context needed to assess such questions.
12. What the Result Does, and Does Not, Mean
The record establishes that this was a prospective, multicenter study of low-energy segment removal using MICOR-304 during cataract surgery. It identifies total lens removal time as the primary endpoint and lists additional surgical, visual acuity, and corneal outcomes. It also describes two cohorts according to cataract grade and records adverse-event counts.
It does not report the primary endpoint mean or its 95% confidence interval. It also does not report numerical analyses of the secondary outcomes. As a result, readers cannot use the registry record to determine the observed lens removal time, its precision, or whether outcomes differed between cohorts. The absence of those results is a limitation of the record, not evidence that the outcomes were either favorable or unfavorable.
The non-randomized, unmasked, parallel design has implications for interpretation. The cohorts are not like-for-like control groups: they are distinguished by cataract severity and both are scheduled for the same procedure. If cohort outcomes were compared, those differences in group definition would need to be considered. A descriptive contrast would not by itself show that the procedure caused an outcome.
The safety entries document the counts recorded in the registry, but they do not provide enough detail to judge event relatedness, timing, or comparative risk. The listing of Pneumonia at 1.8% is not accompanied by cohort attribution or contextual detail in the registry record.
In general, a clinical outcome estimate is most informative when readers can evaluate its magnitude, precision, analysis population, and assumptions. The registered descriptions alone do not provide those elements for the primary endpoint. The record is therefore useful for understanding the study’s stated design and outcomes, but it does not support conclusions about the size, precision, or causal meaning of the clinical results.
13. Why This Trial Matters Statistically
This trial is statistically notable for the distinction between a registered outcome and a reported result. Total lens removal time is carefully defined as two procedural phases, and the record identifies a mean with a 95% confidence interval as the intended summary. However, the numerical estimate and interval are not reported. Without them, there is no basis in the registry record for describing the typical time or the uncertainty around it.
The cohort structure also matters. The study is non-randomized and groups subjects according to cataract severity, with both groups scheduled for the MICOR-304 procedure. This design can describe outcomes in the stated cohorts, but it does not create a randomized control comparison. Any difference between groups could reflect the severity distinction or other factors rather than a causal effect.
The registered range of outcomes raises additional statistical questions. Outcomes include procedural duration, vision at follow-up, and corneal measures. Multiple outcomes and assessment times can complicate interpretation, especially when a testing strategy is not described. The registry record lists 39 outcome measures and 0 analyses, and does not report a multiplicity plan or numerical analyses.
The study’s statistical importance therefore lies partly in what cannot be evaluated from the record: endpoint precision, missing-data handling, analysis populations, adjustment for confounding, and the interpretation of secondary outcomes. Those details are essential for judging how much weight to give observed results. The registry record does not report them, so the design and outcome definitions can be described, but the statistical evidence for clinical outcomes cannot be characterized.
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 primary limitation for statistical interpretation is that the registry record does not report the primary endpoint results. Although total lens removal time is defined and its intended summary is specified, the mean and 95% confidence interval are absent. No numerical secondary-outcome analyses are reported either. The record’s listing of 39 outcome measures alongside 0 analyses leaves the magnitude and precision of outcomes unavailable.
The non-randomized design limits causal comparisons. Cohorts are based on cataract grade, and both are scheduled to undergo the described procedure. They are not randomized arms receiving alternative procedures. The registry record does not report adjustment for differences between cohorts or the variables that such an adjustment might use.
The record does not report the primary-outcome analysis population, numbers contributing measurements, missing-data handling, or details of outcome distributions. It also does not report a statistical analysis plan or multiplicity strategy. These omissions prevent evaluation of whether estimates might be affected by incomplete follow-up, analytic choices, or the number of outcomes considered.
Safety interpretation is limited by the lack of event detail and context. The record provides counts and lists Pneumonia at 1.8% among serious event terms, but does not report the term’s cohort attribution, timing, relatedness, or further clinical characterization. These limitations concern what can be interpreted from the registry record; they should not be taken as evidence about unreported findings.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Assessment of Low Energy Lens Fragmentation Cataract Extraction in Patients Undergoing Cataract Surgery — NCT04747834.
- Registry record last updated 2024-06-06; status last verified 2024-06.
- Results first posted 2024-06-06.
- 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
NCT04747834 is a completed, prospective, multicenter, non-randomized, unmasked, parallel study of MICOR-304 for low-energy lens removal during cataract surgery. Enrollment is listed as 100. The study describes two cohorts defined by cataract severity, with both scheduled to undergo the device procedure.
Total lens removal time, measured in seconds, is the primary outcome. The registry record lists 39 outcome measures and 0 analyses. It does not report primary or secondary outcome results, confidence interval bounds, missing-data methods, or a statistical analysis plan. The adverse-event listing reports cohort-specific counts, deaths listed as 0 in both cohorts, and Pneumonia at 1.8% among serious adverse event terms. The non-randomized cohort structure does not support treating the groups as like-for-like controls.