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 Effectiveness of the Calhoun Vision Light Adjustable Intraocular Lens (LAL) (NCT00845520), a randomized na study. The primary outcome is Percentage of Eyes Achieving a Manifest Refraction Spherical Equivalent (MRSE) Within ± 0.50 D of the Intended Adjustment Target.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00845520 |
| Phase | NA |
| Condition | Cataracts |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 74 |
| Arms in the primary outcome | 3 |
| Lead sponsor | Calhoun Vision, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
People undergoing cataract extraction and receiving an intraocular lens. The registry describes the primary endpoint population as ITT and reports enrollment of 74. The endpoint is expressed as a percentage of eyes; the registry does not report whether each participant contributed an eye or how this was handled in the analysis.
Intervention
Implantation of a Light Adjustable Lens (LAL), with postoperative refractive adjustment and lock-in treatments using the Light Delivery Device (LDD). The study evaluated three intended postoperative MRSE targets: +1.00 D, -1.00 D, and 0.00 D. The registry describes the lens power as calculated for the assigned target.
Comparator
The three target groups are the relevant comparison groups. They differ in the intended postoperative MRSE target, rather than representing a comparison of the LAL with a different lens or with no treatment. The registry does not report a separate control intervention.
Primary question
At 6 months post-operative, what percentage of eyes achieved an MRSE within ± 0.50 D of the intended adjustment target? The registry says the endpoint was intended to assess predictability of postoperative refractive adjustment and that all three arms had the same endpoint.
The study’s stated objective was to evaluate the safety and effectiveness of the LAL and LDD for visual correction of aphakia, including treatment of postoperative residual refractive error through refractive adjustment and lock-in treatments. The primary endpoint therefore concerns how closely the postoperative refractive result falls to a prespecified target. It does not by itself describe visual acuity, patient experience, or every aspect of safety.
The posted results give percentages separately for the three target groups. The registry description says the endpoint results were presented as one combined cohort because the arms shared the endpoint, while the posted results list an arm-level percentage for each group. No formal comparison among the target groups is reported in the registry record.
3. Trial Design
The registry identifies this as a prospective, multicenter clinical study with randomized allocation, no masking, and a parallel-group model. Its status is completed. The registry lists 74 enrolled participants and identifies cataracts as the condition under study. The listed phase is NA.
Participants were assigned to a lens implantation group defined by the intended postoperative MRSE target. The three targets were +1.00 D, -1.00 D, and 0.00 D. The arm descriptions state that lens implant power was calculated for the corresponding postoperative target. The purpose was to evaluate postoperative adjustment of the implanted LAL, not to compare different device types.
The registry identifies the primary endpoint as the percentage of eyes achieving MRSE within ± 0.50 D of the intended adjustment target at 6 months post-operative. Its description states that all arms shared the endpoint and that results were presented as a combined cohort. The posted results list 78.3% for the -1.00 D target arm, 80.0% for the +1.00 D target arm, and 79.2% for the 0.00 D target arm. The associated arm counts are 23, 25, and 24, respectively.
Randomized allocation can help make groups comparable in expectation, but the registry does not report the sequence-generation procedure, allocation concealment, or other implementation details. With no masking, participants and study personnel were not masked according to the registry classification; the record does not explain which outcome assessors, if any, were masked. The protocol details, including the planned sample-size justification, are not reported in the registry record.
The registry lists one secondary outcome: percentage of participants with eyes with improvement in uncorrected visual acuity (UCVA). The registry record does not include a posted result for that secondary outcome in the registry record. The number of analyses is listed as zero, and no inferential arm comparison is reported.
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 | Lens Implant Power +1.00 D Target | Lens Implant Power -1.00 D Target | Lens Implant Power 0.00 D Target |
|---|---|---|---|
| STARTED | 25 | 25 | 24 |
| COMPLETED | 23 | 23 | 23 |
| NOT COMPLETED | 2 | 2 | 1 |
Reasons for not completing this period:
| Reason | Lens Implant Power +1.00 D Target | Lens Implant Power -1.00 D Target | Lens Implant Power 0.00 D Target |
|---|---|---|---|
| Death | 1 | 2 | 0 |
| Lost to Follow-up | 1 | 0 | 0 |
| Adverse Event | 0 | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: ITT
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 | Lens Implant Power +1.00 D Target | Lens Implant Power 0.00 D Target | Lens Implant Power -1.00 D Target | Total |
|---|---|---|---|---|---|
| Participants analysed | 25 | 24 | 25 | 74 | |
| Age, Continuous | years | 66.3 (SD 9.3) | 65.6 (SD 7.3) | 65.9 (SD 9.2) | 66.1 (SD 8.6) |
| Sex: Female, Male: Female | Participants | 15 | 17 | 12 | 44 |
| Sex: Female, Male: Male | Participants | 10 | 7 | 13 | 30 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 1 | 0 | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 | 0 | 0 | 1 |
| Race (NIH/OMB): White | Participants | 21 | 15 | 19 | 55 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 3 | 8 | 6 | 17 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Eyes Achieving a Manifest Refraction Spherical Equivalent (MRSE) Within ± 0.50 D of the Intended Adjustment Target, measured over 6 months post-operative.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of eyes |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the percentage of eyes with a manifest refraction spherical equivalent (MRSE) within ± 0.50 D of the intended adjustment target at 6 months post-operative. MRSE is a summary of refractive error based on the measured spherical and cylindrical components of a refraction. In this trial, the target was the planned postoperative refractive value associated with the assigned lens implantation group.
This endpoint is used to describe predictability: it asks how often the observed refractive result fell within a specified tolerance around the intended target. A proportion within a tolerance can be easier to interpret than a group average alone, because an average may conceal how widely individual results vary. General statistical point: a target-range endpoint describes the frequency of results meeting a chosen criterion; it does not convey the full distribution of refractive outcomes or the size and direction of every deviation.
The registry identifies the measure as a percentage of eyes and the analysis population as ITT. Its endpoint description gives 75% as the stated expectation for eyes within the target range at the point of stability. That figure is part of the endpoint description, not a reported confidence limit or a statistical test result. The posted arm values are 78.3%, 80.0%, and 79.2%. No confidence intervals, standard errors, or p-values for these proportions are reported in the registry record.
The stated assessment time is 6 months post-operative. The registry does not provide further detail on how stability was defined, how missing refractions were handled, or whether results were adjusted for other factors.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary endpoint values are 78.3% in the Lens Implant Power -1.00 D Target group, 80.0% in the Lens Implant Power +1.00 D Target group, and 79.2% in the Lens Implant Power 0.00 D Target group. Each value describes the proportion of eyes reported as achieving MRSE within ± 0.50 D of the intended adjustment target at 6 months post-operative. They are descriptive arm-level results.
The registry describes the endpoint as a combined-cohort result because all three arms shared the same endpoint, but the posted results give separate values by target group. A combined estimate is not reported in the results, so no overall percentage should be inferred by averaging the arm values or combining their counts. The record also does not report a statistical test comparing the groups. The small numerical differences among the posted percentages should therefore not be treated as evidence that one target group performed differently from another.
Precision is difficult to assess from percentages alone. A confidence interval would show a range of values compatible with the data under the statistical model used, reflecting sampling uncertainty. No confidence intervals are reported in the registry record for these endpoint percentages. Without them, the posted values do not show how uncertain each estimate is. The arm counts listed alongside the endpoint are 23, 25, and 24, but the record does not explain the exact denominator used for each percentage or how missing endpoint data were treated.
The endpoint is a threshold measure. It records whether an eye fell within ± 0.50 D of its target, not the average signed refractive error, the spread of individual results, or the frequency and direction of results outside the target range. Those details are not reported in the registry record. The percentages consequently provide a focused description of target attainment, rather than a complete account of refractive outcomes.
The stated 75% in the endpoint description is a target or expectation recorded in the description. It is not a comparator group, a confidence interval, or a hypothesis test. The registry does not report a formal test of the observed arm results against that stated value. No conclusion about statistical significance can be drawn from the percentages alone.
The primary outcome population is labeled ITT, but the registry does not explain the analysis procedures supporting that label. There is no reported account of exclusions, deviations from assignment, or missing data. The results should therefore be read as registry-posted descriptive values, with the population and handling details limited to what the record states.
9. Statistical Methods Explained
Statistical methods help distinguish a descriptive result from evidence about uncertainty or group differences. The registry reports arm-level percentages for the primary endpoint, but does not report confidence intervals, p-values, or a formal comparison among the target groups. The explanations below describe general statistical concepts; they are not claims about procedures used in this study unless the registry record explicitly identifies them.
What does the endpoint percentage describe?
For each target group, the percentage describes the share of eyes reported to have an MRSE within ± 0.50 D of the intended adjustment target. This is a binary classification for each eye: the result either falls inside the stated range or it does not. The measure is useful for communicating how often a specified target criterion was met, but it does not preserve the exact refractive value for each eye. Results just inside and far inside the range count alike under this endpoint, as do results outside the range in either direction.
The registry lists the primary population as ITT. In general, an intention-to-treat approach analyzes participants according to randomized assignment, but details matter for outcomes measured at the eye level. The record does not explain whether the analysis included all randomized participants, how it handled participants without an assessable refraction, or how the eye-level outcome was connected to participant-level assignment. The ITT label alone does not answer these implementation questions.
Why do confidence intervals matter?
General statistical explanation: a confidence interval describes uncertainty around an estimate under a specified method and assumptions. For a proportion, it gives a range of plausible values for the underlying proportion, rather than treating the observed percentage as exact. Its width depends in part on the amount of information available and on the analysis method. A percentage without an interval can indicate the observed result but gives limited information about its precision.
No confidence intervals are reported for the primary endpoint percentages in the registry record. No method for estimating uncertainty is stated. Thus, the displayed point estimates cannot establish whether the underlying target-attainment proportions are close to the observed percentages or could plausibly be meaningfully different.
What would a group comparison require?
General statistical explanation: comparing randomized groups usually requires a defined estimand, a method for comparing the endpoint, and an uncertainty measure. A statistical test may assess compatibility with a specified null hypothesis, while a confidence interval can describe the range of effect estimates compatible with the data under the method. Neither should be replaced by simply inspecting which percentage is numerically largest.
The registry reports randomization and parallel groups, but no inferential comparison is posted. It does not report an adjusted analysis, a prespecified contrast among target groups, or a test of the endpoint against the 75% expectation stated in the endpoint description. The record therefore supports a descriptive reading of the three percentages, not a claim of statistically established differences or equivalence.
Why can over-dispersion matter?
General statistical explanation: for count outcomes, a simple model may assume that variability follows a particular relationship to the mean. Over-dispersion means the data vary more than that model expects. If it is ignored, standard errors can be too small and confidence intervals or tests can give an overly confident impression. This issue is relevant to some count-data analyses, but the primary endpoint in this trial is a percentage of eyes meeting a criterion, and the registry does not report a model-based count analysis or an over-dispersion assessment.
How should planning calculations be read?
General statistical explanation: a sample-size calculation is a planning exercise based on assumptions about an effect, variability, significance level, allocation, and analysis method. It is not a measure of how much power a completed trial actually had. The planning illustrations associated with this study are based on the observed effect and stated assumptions, and are not the trial's own design justification. They should be read as hypothetical planning scenarios, not as observed power. The registry record does not report the trial's original sample-size justification.
Likewise, a recalculated unadjusted result from posted summary statistics would not replace a sponsor's own analysis if the two differed. In this record, no discrepancy is identified. However, no arm-comparison analysis is posted for this endpoint, so there is no reported sponsor comparison or recalculated comparison to interpret.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary endpoint and one secondary outcome: percentage of participants with eyes with improvement in UCVA. It lists three outcome measures, but the record does not specify whether the additional measures were prespecified, how they relate to the listed outcomes, or how they were analyzed. No secondary outcome result is included in the registry record.
Multiplicity arises when several outcomes, time points, or group comparisons are tested. General statistical explanation: running multiple tests can increase the chance of finding at least one apparently notable result by chance, so a statistical plan may define which comparisons are primary or adjust for multiple testing. The registry record does not report a multiplicity strategy, a hierarchy of tests, or an analysis plan for multiple comparisons. Since no inferential tests are posted for the primary endpoint, the record does not support a conclusion about how multiplicity was handled in the trial analyses.
The primary population is identified as ITT, but the registry record does not describe missing-data handling. It does not report how many eyes had an assessable endpoint, whether missing refractions occurred, whether any imputation was used, or whether a sensitivity analysis was performed. These details matter because a percentage can depend on which observations are included in its denominator and how unavailable outcomes are treated.
The registry does not report a protocol-level statistical analysis plan, interim analyses, or a sample-size justification. Those absences do not establish that such procedures were not used; they mean the information is not reported in the registry record. The posted percentages should therefore be interpreted without assumptions about unreported analysis decisions.
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 |
|---|---|---|---|
| Lens Implant Power of +1.00 D Target | 3 | 25 | 12.0% |
| Lens Implant Power of -1.00 D Target | 2 | 25 | 8.0% |
| Lens Implant Power of 0.00 D | 1 | 24 | 4.2% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Lens Implant Power of +1.00 D Target | 0 of 25 |
| Lens Implant Power of -1.00 D Target | 2 of 25 |
| Lens Implant Power of 0.00 D | 1 of 24 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Lens Implant Power of +1.00 D Target | 18 of 25 |
| Lens Implant Power of -1.00 D Target | 15 of 25 |
| Lens Implant Power of 0.00 D | 14 of 24 |
Most frequent serious adverse event terms
| Event term | Organ system | Lens Implant Power of +1.00 D Target | Lens Implant Power of -1.00 D Target | Lens Implant Power of 0.00 D |
|---|---|---|---|---|
| Secondary Surgical Intervention | Eye disorders | 1 of 25 | 1 of 25 | 1 of 24 |
| Stroke | Nervous system disorders | 0 of 25 | 1 of 25 | 0 of 24 |
| Optic neuritis | Eye disorders | 1 of 25 | 0 of 25 | 0 of 24 |
| epiretinal membrane and macular hole | Eye disorders | 0 of 25 | 0 of 25 | 1 of 24 |
| wet age related macular degeneration | Eye disorders | 0 of 25 | 1 of 25 | 0 of 24 |
| macular edema secondary to epiretinal membrate | Eye disorders | 1 of 25 | 0 of 25 | 0 of 24 |
| heart attack with pacemaker implanted | Cardiac disorders | 0 of 25 | 0 of 25 | 1 of 24 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Lens Implant Power of +1.00 D Target | Lens Implant Power of -1.00 D Target | Lens Implant Power of 0.00 D |
|---|---|---|---|---|
| Posterior Capsular Opacity | Eye disorders | 17 of 25 | 15 of 25 | 13 of 24 |
| Blepharitis | Eye disorders | 1 of 25 | 1 of 25 | 2 of 24 |
Serious events with the highest arm-level rate: secondary surgical intervention (4.2%), epiretinal membrane and macular hole (4.2%), heart attack with pacemaker implanted (4.2%), stroke (4.0%), optic neuritis (4.0%).
The registry reports serious adverse event counts by lens target group: 3 for the +1.00 D target, 2 for the -1.00 D target, and 1 for the 0.00 D target. The corresponding serious-event populations at risk are 25, 25, and 24. The record also lists other adverse event counts of 18, 15, and 14 for those groups, with at-risk populations of 25, 25, and 24. Death counts are 0, 2, and 1, respectively. These counts describe what the registry reports; they do not establish cause.
The safety populations do not align exactly with the arm counts listed for the primary endpoint: the -1.00 D group has an endpoint arm count of 23 and a serious-event population at risk of 25. The registry does not explain this difference. Safety counts should not be converted into rates using a denominator chosen from another outcome listing.
The record lists serious-event terms including Secondary Surgical Intervention, epiretinal membrane and macular hole, heart attack with pacemaker implanted, Stroke, Optic neuritis, and wet age related macular degeneration, with percentages as posted. These terms should not be interpreted as events caused by the lens or study procedures. The registry record does not provide enough detail to establish relatedness, timing, severity criteria, or whether a term occurred more than once within a group. Counts and event terms are safety descriptions, not causal comparisons.
12. What the Result Does, and Does Not, Mean
The primary results describe target attainment as defined by the registry: MRSE within ± 0.50 D of the intended adjustment target at 6 months post-operative. The posted percentages are 78.3% for the -1.00 D target, 80.0% for the +1.00 D target, and 79.2% for the 0.00 D target. They show the recorded proportion meeting that criterion in each listed group. They do not, on their own, quantify uncertainty or demonstrate a difference between groups.
The endpoint is narrower than the study’s overall objective. It addresses refractive predictability, while the stated objective also refers to safety and effectiveness of the LAL and LDD for visual correction of aphakia and treatment of residual refractive error. One endpoint cannot summarize all visual outcomes, the range of refractive results, or all safety considerations. The registry lists improvement in UCVA as a secondary outcome, but the result is not reported in the record.
These results do not establish how the LAL compares with another lens or with no treatment. The three groups differ by intended refractive target; they are not described as different device comparators. Nor do the values establish that results are equivalent across target groups. Equivalence requires a specified margin and an analysis designed to assess it, and neither is reported in the registry record.
The absence of confidence intervals and inferential tests limits conclusions about precision and statistical evidence. The absence of reported analysis details also limits assessment of missing data, the eye-level analysis, and the handling of participants after randomization. These are gaps in what the registry record reports, not proof that the underlying study did not address them.
Safety counts must also be read descriptively. The registry reports serious and other adverse events by target group, but the counts do not establish whether an event was related to the lens or procedure. Without additional information on event definitions, timing, follow-up, and attribution, they cannot support a causal conclusion.
13. Why This Trial Matters Statistically
This study is statistically notable for using a target-range endpoint to describe refractive predictability after an adjustable lens implantation. Rather than reporting only a mean refractive result, the primary measure asks how often eyes fell within a defined tolerance of their intended adjustment target. That makes the endpoint directly interpretable as criterion attainment, while also making clear that it omits the magnitude and direction of results outside the range.
The randomized, parallel-group design assigns participants to different intended refractive targets, providing a structure for examining outcomes by target. The posted primary results, however, are descriptive arm percentages without reported confidence intervals or inferential comparisons. This distinction is important: randomization is a design feature, while conclusions about group differences depend on the analysis and its uncertainty, which are not reported for this endpoint.
The registry’s description says the shared endpoint was presented as a combined cohort, whereas the posted results list values by arm. That makes it important to distinguish the stated endpoint plan from the results as displayed and not to create a combined estimate by calculation. The record also labels the primary population ITT without explaining the details of the eye-level analysis or missing-data handling.
The study illustrates why readers should separate endpoint definition, observed percentage, precision, and causal interpretation. Each answers a different question. The posted figures communicate target attainment among the analyzed observations as reported, but they do not reveal the distribution of individual refractive outcomes, establish differences between target groups, or identify whether adverse events were caused by the intervention. Those boundaries help keep the statistical interpretation proportional to what the registry reports.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
Several trial-specific details needed for a fuller interpretation are not reported in the registry record. Although allocation is classified as randomized, the method of sequence generation and allocation concealment is not described. Masking is listed as none, but the record does not specify whether outcome assessors were masked or how the absence of masking might have affected measurement or follow-up.
The primary endpoint is expressed as a percentage of eyes, while the registry’s primary population is labeled ITT. The record does not explain how participant assignment was linked to eye-level observations, whether both eyes could contribute, or how any within-participant correlation was handled. It also does not report the exact denominators used for the endpoint percentages or how missing outcome measurements were addressed.
The endpoint description refers to stability and gives 75% as the expected target-range proportion, while the timeframe is 6 months post-operative. The registry does not define stability in further detail or report a formal test against that expectation. It also does not provide confidence intervals or a formal comparison among the target groups. The presented percentages therefore have limited information about precision and comparative evidence.
The safety populations at risk differ from at least one endpoint arm count, and the registry does not explain why. Event terms and counts are reported without the detail needed to interpret timing, recurrence, or attribution. The record also does not include results for the listed UCVA secondary outcome in the registry record. Protocol details, the original sample-size justification, interim analyses, and a statistical analysis plan are not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety and Effectiveness of the Calhoun Vision Light Adjustable Intraocular Lens (LAL) — NCT00845520.
- Registry record last updated 2018-07-06; status last verified 2018-06.
- Results first posted 2018-07-06.
- 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.
Continue through the Clinical Biostats statistical pathway
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18. Record Summary
NCT00845520 is a completed, prospective, multicenter, randomized, unmasked, parallel-group study of the Light Adjustable Lens in people undergoing cataract extraction. Enrollment is listed as 74. The three implantation groups used intended postoperative MRSE targets of +1.00 D, -1.00 D, and 0.00 D.
The primary endpoint was the percentage of eyes with MRSE within ± 0.50 D of the intended adjustment target at 6 months post-operative. The posted arm values are 78.3%, 80.0%, and 79.2% for the -1.00 D, +1.00 D, and 0.00 D target groups, respectively. No confidence intervals or inferential comparison are reported in the registry record.
The registry also lists improvement in UCVA as a secondary outcome and reports adverse event counts by target group. Important analysis details, including missing-data handling, the endpoint denominators, and the original sample-size justification, are not reported in the registry record.