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 Safety and Performance of Miami InnFocus Drainage Implant (MIDI Arrow) Glaucoma Drainage Implant (NCT01563237), a na na study. The primary outcome is Number of Eyes With Study Success.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01563237 |
| Phase | NA |
| Condition | Primary Open Angle Glaucoma |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 69 |
| Arms in the primary outcome | n/a |
| Lead sponsor | InnFocus Inc. |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with primary open-angle glaucoma whose condition was inadequately controlled on maximum tolerated medical therapy. The registry summary describes an intraocular pressure eligibility range from 18 mm Hg through 40 mm Hg. The primary endpoint population is described as the Intent-to-Treat population: enrolled eyes that signed informed consent and attended the procedure visit to receive the assigned therapy.
Intervention
The intervention was implantation of the MIDI Arrow, a glaucoma drainage implant. The record identifies it as a device and does not describe a separate medication or co-intervention as the study treatment.
Comparator
There was no comparison group in the registered design. The study is described as a single-group study, with allocation and masking both recorded as NA or none. It therefore does not provide a randomized, concurrent control comparison.
Primary question
The primary question was how many implanted eyes met the study’s definition of success at months 6, 9, 12 and 24. The endpoint description connects success with sustained control of intraocular pressure over 24 months from baseline. The registry record does not report the observed count of successful eyes or provide the operational criteria used to classify success.
3. Trial Design
NCT01563237 is a completed, single-group device study of the MIDI Arrow drainage implant. It lists primary open-angle glaucoma as the condition and InnFocus Inc. as the sponsor. The registry gives a planned enrollment of 69. The study start is recorded as 2011-06 and primary completion as 2016-12.
The intervention is implantation of the MIDI Arrow. The design is not randomized: allocation is recorded as NA, and the model is single group. Masking is recorded as none. These features mean that the registry does not describe a blinded comparison of the device with another treatment or with a control group. The posted record therefore cannot isolate a treatment contrast from changes over time or other influences using a concurrent randomized comparison.
The primary endpoint is a count of implanted eyes classified as study successes, with assessments specified at months 6, 9, 12 and 24. The population definition refers to enrolled eyes that signed informed consent and attended the procedure visit to receive the assigned therapy. The record also lists intraocular pressure change from baseline as a secondary outcome. It reports two outcome measures, but no outcome analyses are recorded.
The safety group is titled Study Eyes Selected to be Operated Within the Study and lists 74 eyes at risk for both serious and other adverse events. That count differs from the enrollment figure of 69, and the registry does not explain the relationship between these counts. It is important not to treat the safety denominator as interchangeable with enrollment without further information.
Detailed protocol information about eligibility beyond the summary, follow-up procedures, outcome adjudication, and analysis methods is not reported in the registry record. The study’s completed status indicates the record’s status designation; it does not supply the missing numerical efficacy results.
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 | First Studied Eye | Second Studied Eye |
|---|---|---|
| STARTED | 64 | 5 |
| COMPLETED | 54 | 5 |
| NOT COMPLETED | 10 | 0 |
Reasons for not completing this period:
| Reason | First Studied Eye | Second Studied Eye |
|---|---|---|
| Lost to Follow-up | 6 | 0 |
| Withdrawal by Subject | 1 | 0 |
| Adverse Event | 1 | 0 |
| Medical Reasons | 1 | 0 |
| Death | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: The Intent-to-Treat (ITT) population included all enrolled eyes who have signed the informed consent and attended the procedure visit to receive the assigned therapy under evaluation (MIDI Arrow).
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: The Intent-to-Treat (ITT) population included all enrolled subject who have signed the informed consent and attended the procedure visit to receive the assigned therapy under evaluation (MIDI Arrow).
| Characteristic | Unit | MIDI Arrow |
|---|---|---|
| Participants analysed | 67 | |
| Age, Continuous | years | 64.1 (SD 13.1) |
| Sex: Female, Male: Female | Participants | 28 |
| Sex: Female, Male: Male | Participants | 39 |
| Region of Enrollment: France | Participants | 67 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Eyes With Study Success, measured over Months 6, 9, 12 and 24.
| Element | Registry entry |
|---|---|
| Result type | Count Of Units |
| Measure of spread | not applicable |
| Unit | Implanted eyes |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the number of implanted eyes with study success. Its stated timeframe is months 6, 9, 12 and 24, and its description says that success reflected sustained control of intraocular pressure over 24 months from baseline. This makes the endpoint a count of eyes meeting a classification, rather than a mean change or a time-to-event measure.
A sustained-control endpoint can represent whether an eye met a prespecified clinical or technical target across follow-up, rather than capturing only a single pressure measurement. In general, repeated assessment can make the endpoint relevant to persistence of control over time. However, the registry record does not report the exact threshold for success, whether success required meeting criteria at every assessment, or how missing visits or additional procedures affected classification. Without those rules, the label alone is not enough to reproduce the endpoint or assess how borderline cases were handled.
The recorded primary outcome is a count, but the number of eyes classified as successful and any corresponding rate or uncertainty estimate are not reported in the registry record. The secondary outcome is intraocular pressure change from baseline; its numerical results are also not reported. Consequently, the endpoint description states what the study intended to measure, not what the posted results found.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes that this was a completed, single-group study of the MIDI Arrow in primary open-angle glaucoma, with a planned enrollment of 69. It identifies a primary endpoint concerned with study success over 24 months from baseline, assessed at months 6, 9, 12 and 24. But it does not report the number of eyes that met that endpoint, an estimated success rate, or an uncertainty interval. The registry’s record of zero outcome analyses reinforces that no numerical analysis results are available in the posted record.
That absence limits interpretation. A stated endpoint is not itself a result: readers cannot infer how many eyes achieved success, how consistently pressure was controlled, or how precise an estimate might have been. The secondary outcome, intraocular pressure change from baseline, is named but also lacks numerical results. Thus, no conclusion about the observed direction or size of change can be drawn from the outcome information recorded.
The design also limits causal interpretation. A single-group study without a randomized comparator can describe outcomes among the studied eyes, but it cannot offer a like-for-like comparison with an untreated or alternative-treatment group. Changes during follow-up may have multiple explanations, and the record does not include a control contrast to help separate them. No masking was recorded, which also means the registry does not describe a blinded outcome assessment; whether any individual measurement or classification was independently assessed is not reported.
The safety record contains 10 eyes with serious adverse events among 74 at risk and 68 eyes with other adverse events among 74 at risk. It also lists 1 death. These figures describe reported events in the specified safety group; they do not by themselves establish whether an event was caused by the device. The record does not provide the timing, event-level narratives, or causal attribution needed to interpret those counts further. In addition, the registry reports enrollment of 69 and safety denominators of 74 without explaining the difference.
Overall, the posted record describes what was planned and gives selected safety counts, but it does not provide the primary endpoint result or statistical estimates. The absence of reported results should not be mistaken for evidence of either success or failure. The study-specific effects and their precision are not reported in the registry record.
9. Statistical Methods Explained
The registry describes a single-group study and identifies the primary outcome as a count of implanted eyes with study success. A count endpoint records how many units meet a classification. For interpretation, a count is often accompanied by the number assessed and, where appropriate, a rate or interval estimate. The record gives the endpoint unit as implanted eyes but does not report the observed success count, the number contributing outcome data at each visit, or an estimate of uncertainty.
The endpoint is assessed at months 6, 9, 12 and 24, and its description refers to sustained control of intraocular pressure over 24 months from baseline. In general, repeated assessments can describe whether a target is maintained over follow-up. The exact success rule matters: for example, a protocol could define success using a threshold, a pattern across visits, or other criteria. The operational definition is not reported in the registry record, so the success classification cannot be independently reconstructed from the description alone. How repeated observations were combined is also not reported.
The record names intraocular pressure change from baseline as a secondary outcome. In general, a change score compares a follow-up measurement with a baseline measurement. Its interpretation depends on how baseline and follow-up measurements are defined, which visits contribute, how missing measurements are handled, and what summary measure is used. Those details and the numerical change results are not reported in the registry record.
Confidence intervals are a general way to communicate the statistical uncertainty around an estimate. They describe a range of values compatible with the observed data under the analysis assumptions; they do not guarantee that the true value lies within a particular interval. No confidence interval for the primary or secondary outcome is reported in the registry record. Likewise, no test statistic or outcome p-value is recorded.
The record lists zero outcome analyses. This means the registry entry does not contain an analysis result for the listed outcomes. It does not, by itself, establish what analyses were performed outside the posted record, whether analyses were planned in a protocol, or why results are absent. The statistical analysis plan is not reported in the registry record.
The record’s sample-size assumptions describe planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They state that the effect to detect is a specified fraction of the observed effect; for time-to-event planning, the illustration is described as a total event count, and other illustrations as participants per arm. These are planning assumptions, not the registered trial design: the study itself is single group, not an equal-allocation two-arm comparison. The numerical planning outputs and the observed effect used for them are not reported in the registry record. Any such illustration is a hypothetical planning exercise, not observed power and not evidence about the study’s outcome.
In general, a normal approximation uses an approximate distribution to make planning or inferential calculations simpler. Its appropriateness depends on the data and the quantity being estimated. The record does not describe a statistical model for the primary count endpoint, an approach to repeated measurements, or any variance or distributional assumptions used in outcome analysis. No method for adjustment, covariate inclusion, or subgroup analysis is reported.
For count outcomes, it is also important to distinguish a count from a proportion. A count alone depends on how many eyes were evaluated; a proportion additionally requires a denominator and a clear rule for inclusion. Here the endpoint is identified as a count, but the numerical count and denominator for the primary outcome are absent. The safety denominators are reported separately and should not be substituted for the endpoint population without documentation.
General statistical interpretation should also distinguish statistical uncertainty from clinical importance. An estimate can be precise yet not address every clinically relevant question, and a broad interval can leave substantial uncertainty. In this record, neither the primary estimate nor its precision is available, so that distinction cannot be evaluated from the posted outcome results. The registry’s outcome description and design characteristics support a discussion of what was intended to be measured, not a quantitative conclusion about the measured effect.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures: the primary count of eyes with study success and the secondary outcome of intraocular pressure change from baseline. The primary endpoint is assessed at months 6, 9, 12 and 24. Multiple outcomes and assessment times can create multiple opportunities to examine results. In general, prespecifying a primary endpoint and analysis can help clarify which result is confirmatory and how secondary or repeated assessments should be interpreted.
The statistical plan, including any approach to multiplicity, is not reported in the registry record. It is therefore not possible to determine whether testing across outcomes or visits was adjusted, whether a hierarchy was planned, or how secondary findings were intended to be treated. The record reports zero outcome analyses; this means those analyses are not present in the registry entry, not that a particular multiplicity method was or was not used elsewhere.
The primary population is described as the Intent-to-Treat population of enrolled eyes that signed informed consent and attended the procedure visit to receive the assigned therapy. The record does not explain how eyes with incomplete follow-up, missing pressure measurements, withdrawals, or protocol deviations were handled. It also does not say whether the same population was used for safety summaries and efficacy analyses.
Missing observations can affect an estimate when the availability of follow-up is related to outcomes or participant characteristics. General methods for addressing missing data rely on assumptions, and those assumptions should be stated alongside the analysis. No missing-data method, sensitivity analysis, or visit-specific analysis population is reported in the registry record. Because there are no primary outcome results, the extent of missingness and its potential influence cannot be assessed.
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 |
|---|---|---|---|
| Study Eyes Selected to be Operated Within the Study | 10 | 74 | 13.5% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Study Eyes Selected to be Operated Within the Study | 1 of 74 |
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 |
|---|---|
| Study Eyes Selected to be Operated Within the Study | 68 of 74 |
Most frequent serious adverse event terms
| Event term | Organ system | Study Eyes Selected to be Operated Within the Study |
|---|---|---|
| Intraocular Pressure Increased | Investigations | 3 of 74 |
| Gallbladder Operation | Surgical and medical procedures | 1 of 74 |
| Medical Device Repositioning | Surgical and medical procedures | 1 of 74 |
| Macular Degeneration | Eye disorders | 1 of 74 |
| Macular Oedema | Eye disorders | 1 of 74 |
| Visual Acuity Reduced | Eye disorders | 1 of 74 |
| Conjunctival Filtering Bleb Leak | Injury, poisoning and procedural complications | 1 of 74 |
| Perforation Bile Duct | Hepatobiliary disorders | 1 of 74 |
| Dacryocystitis | Infections and infestations | 1 of 74 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Study Eyes Selected to be Operated Within the Study |
|---|---|---|
| Intraocular pressure increased | Investigations | 39 of 74 |
| Hyphaema | Eye disorders | 19 of 74 |
| Cataract | Eye disorders | 17 of 74 |
| Hypotony of eye | Eye disorders | 13 of 74 |
| Keratitis | Eye disorders | 12 of 74 |
| Drug Intolerance | General disorders | 7 of 74 |
| Eye irritation | Eye disorders | 5 of 74 |
| Ulcerative keratitis | Eye disorders | 5 of 74 |
| Visual acuity reduced | Eye disorders | 4 of 74 |
| Eyelid ptosis | Eye disorders | 4 of 74 |
Serious events with the highest arm-level rate: intraocular pressure increased (4.1%), gallbladder operation (1.4%), medical device repositioning (1.4%), macular degeneration (1.4%), macular oedema (1.4%).
The registry’s safety group is titled Study Eyes Selected to be Operated Within the Study. It reports 74 eyes at risk for serious adverse events, of which 10 were affected, and 74 at risk for other adverse events, of which 68 were affected. It also records 1 death. These are counts for the registry’s specified safety group; the record does not explain why the at-risk count of 74 differs from the planned enrollment of 69.
The listed serious-event terms and percentages are Intraocular Pressure Increased, 4.1%; Gallbladder Operation, 1.4%; Medical Device Repositioning, 1.4%; Macular Degeneration, 1.4%; Macular Oedema, 1.4%; and Visual Acuity Reduced, 1.4%. The percentages are presented as registry entries and should not be converted into counts without additional information. The record does not say whether people could have more than one event, whether the percentages refer to people or events, or how the terms relate to the count of affected eyes.
Adverse-event counts describe events recorded during the study; they do not establish that the device caused them. The registry record does not report causal attribution, timing, severity details beyond the serious-event categorization, or event narratives. The death count likewise should not be interpreted as a device-related death in the absence of attribution information. These limitations constrain what can be inferred from the safety figures.
12. What the Result Does, and Does Not, Mean
The record establishes the study’s focus: evaluating the MIDI Arrow in a single group of people with primary open-angle glaucoma whose condition was inadequately controlled on maximum tolerated medical therapy. It defines a primary endpoint based on the number of implanted eyes meeting a success classification over 24 months from baseline, with assessments at months 6, 9, 12 and 24. It also records a secondary outcome of intraocular pressure change from baseline.
Those descriptions do not tell readers what the study found. The primary success count, the corresponding denominator, the pressure-change results, and estimates of uncertainty are not reported in the registry record. The number of outcome analyses recorded is zero. Therefore, the posted information does not support a numerical conclusion about the degree of pressure control or the proportion of eyes meeting the endpoint. It also does not establish that the device succeeded or failed.
The single-group design does not include a concurrent randomized control group. Even if outcome data were available, a within-group description would not have the same interpretive role as a randomized comparison: it would not directly estimate how outcomes differed from those under another treatment or no study intervention. The registry does not report a comparator arm, and allocation is recorded as NA.
Safety counts are available, but they have their own limits. The registry reports 10 eyes affected by serious adverse events and 68 affected by other adverse events, each among 74 at risk, plus 1 death. These counts do not establish causation, and the discrepancy between the reported enrollment of 69 and safety denominator of 74 is unexplained. The record also does not provide enough event detail to characterize timing or attribution.
In general, the meaning of a clinical trial result depends on the outcome definition, the population analyzed, the completeness of follow-up, the analysis methods, and the precision of estimates. Several of those elements are not reported, and the numerical primary result is absent. The study can be described from its design and registry entries, but its efficacy findings cannot be evaluated from the posted results.
13. Why This Trial Matters Statistically
This trial is statistically notable for the gap between a clearly named endpoint and the absence of a posted endpoint result. The registry specifies a count of implanted eyes with study success and describes sustained control over 24 months from baseline, but it does not provide the count, denominator, or an estimate of precision. This illustrates why an endpoint definition and a numerical result are both needed for quantitative interpretation.
The design also matters. A single-group study can describe outcomes among the treated group, but without a randomized comparator it cannot provide a direct, like-for-like treatment contrast. The record’s allocation entry is NA and the study model is single group. Readers should therefore distinguish the question the study set out to assess from the questions its design can address.
The safety record supplies some event counts and selected term percentages, but its denominators do not align transparently with the enrollment figure: 69 enrolled and 74 eyes at risk are both reported, with no explanation of the difference. This is a practical reminder that population definitions and analysis denominators are central to interpreting any rate or count. The record does not clarify the relationship between enrolled eyes, operated eyes, and eyes included in safety summaries.
Finally, the entry lists two outcome measures and zero outcome analyses. Without results, analysis methods, or information on missing observations and multiplicity, readers cannot evaluate the statistical evidence, its precision, or the robustness of conclusions. The record is useful for identifying the intended endpoint and the limitations of the documented evidence, while leaving the central numerical outcome question unanswered.
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.
A central limitation is that the primary endpoint result is not reported in the registry record. Although the endpoint is described as a count of implanted eyes with study success, no success count, analysis denominator, rate, confidence interval, or test result is available. The secondary outcome of intraocular pressure change from baseline is named but likewise has no numerical result. The registry records zero outcome analyses.
The success criteria are not described in operational detail. The record says success reflected sustained control of intraocular pressure over 24 months from baseline and lists assessments at months 6, 9, 12 and 24, but it does not state the pressure threshold, how measurements across visits were combined, or whether additional events affected classification. Follow-up completeness and handling of missing measurements are not reported.
The design is single group, with no randomized comparator, and masking is recorded as none. These features restrict direct comparative interpretation. The statistical analysis plan, covariate adjustments, model choices, multiplicity approach, and sensitivity analyses are not reported in the registry record. The sample-size assumptions describe hypothetical planning illustrations, but their numerical outputs and the observed effect used for planning are not available.
There is also an unexplained difference between the planned enrollment of 69 and the safety-group denominator of 74 eyes at risk. The record does not specify how those counts relate to participants, eyes operated on, or the endpoint population. Safety event attribution, event timing, and detailed narratives are not reported. These limitations mean that both efficacy and safety findings are only partly characterized by the registry entries.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety and Performance of Miami InnFocus Drainage Implant (MIDI Arrow) Glaucoma Drainage Implant — NCT01563237.
- Registry record last updated 2021-06-24; status last verified 2021-06.
- Results first posted 2021-05-28.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT01563237 is a completed, single-group device study sponsored by InnFocus Inc. It lists primary open-angle glaucoma, enrollment of 69, and implantation of the MIDI Arrow. The study start is recorded as 2011-06 and primary completion as 2016-12. Allocation is NA and masking is none.
The primary endpoint is the number of implanted eyes with study success at months 6, 9, 12 and 24, described as sustained control of intraocular pressure over 24 months from baseline. Intraocular pressure change from baseline is listed as a secondary outcome. The registry reports two outcome measures and zero analyses; numerical efficacy results are not reported in the registry record.
The safety group lists 74 eyes at risk for serious and other adverse events, with 10 affected by serious events and 68 by other events, and 1 death. The record does not explain the difference between enrollment and the safety denominator or provide event attribution. Its entries describe the registered design and selected safety counts, but leave the primary outcome and its statistical precision unavailable.