RxSight Light Adjustable Lens and Light Delivery Device New Enrollment Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for RxSight Light Adjustable Lens and Light Delivery Device New Enrollment Study (NCT05202808), a randomized na study. The primary outcome is Absolute Manifest Refraction Spherical Equivalent (MRSE) Compared Between the Two Study Groups, LAL and Control.

2. Clinical Question

In statistical terms, the result addresses whether the observed mean MRSE values differ between the randomized groups at the specified time point, and how precisely that difference is estimated. It does not by itself describe all aspects of safety, every secondary outcome, or outcomes at other follow-up times. The record lists rate of endothelial cell density loss and rate of retinal findings as secondary outcomes, but does not provide their results in the information summarized for this comparison.

3. Trial Design

This is a randomized, single-masked, parallel-group study. Participants were assigned to the Light Adjustable Lens and Light Delivery Device group or to the Control IOL group. The record does not identify which people involved in the study were masked, and the arm descriptions do not add details about the masking procedure. The phase is recorded as not applicable.

The study is described as a post-approval study. Its primary objective is stated as comparing the LAL with a monofocal control IOL for safety outcomes. The registry lists an enrollment of 500. For the primary MRSE outcome, the reported group counts are 332 in the LAL and LDD group and 164 in the Control IOL group. The safety record uses at-risk counts of 335 and 165, respectively. These are different outcome-specific counts; the registry information does not explain the reasons for the differences.

The study start date is 2021-12-03, and the primary completion date is 2024-09-11. Its status is completed. The primary MRSE measure is specified at postoperative month 6. The record does not state the timeframe for the listed secondary outcomes in the information available for this analysis.

The random allocation and parallel-group structure support a comparison between assigned groups, but the registry information does not describe allocation concealment, the randomization procedure, masking details, adherence, or treatment received after assignment. It also does not report the original design assumptions used to determine enrollment, such as the anticipated effect or the original target power. The planning illustrations associated with the observed result are not a substitute for those protocol details.

The primary endpoint is a continuous measure summarized with a mean and standard deviation. This supports describing the group averages and their difference, while also considering the spread of individual measurements and uncertainty in the estimated difference. A group mean does not show the full distribution of individual results. The registry record does not provide additional distributional summaries or participant-level data.

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:

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 Absolute Manifest Refraction Spherical Equivalent (MRSE) Compared Between the Two Study Groups, LAL and Control, measured over Postop Month 6.

The primary outcome is titled “Absolute Manifest Refraction Spherical Equivalent (MRSE) Compared Between the Two Study Groups, LAL and Control.” It is measured in diopters, summarized as a mean with a standard deviation, and assessed at postoperative month 6. The posted mean is 0.21 diopters for the LAL and LDD group and 0.345 diopters for the Control IOL group.

As a general statistical description, spherical equivalent expresses a refractive measurement on a single numerical scale. Using a continuous measure allows researchers to compare group averages and to quantify the difference between them. The standard deviation describes how much individual measurements vary around a group mean; it is not a measure of uncertainty in the mean difference.

The record’s endpoint title includes the word “Absolute,” but it does not define that term further in the outcome description. No target range, clinically important difference, or threshold for interpreting the MRSE result is reported in the registry record. The mean comparison therefore describes the observed group-level values and their statistical separation, not whether a particular value is clinically important for an individual. The six-month endpoint also does not establish what the corresponding measurements would be at other time points.

7. Results Posted in the Registry

• Light Adjustable Lens (LAL) and Light Delivery Device (LDD): mean 0.21 versus 0.34 on control; difference -0.13 (95% CI -0.18 to -0.09), standardized effect d = -0.58; z-test p = <0.001.

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean difference describe?

A mean is the arithmetic average of measurements within a group. For a continuous outcome such as MRSE, the mean provides a concise description of the group’s central value. Comparing two means gives a contrast in the outcome’s units. Here, the posted contrast is -0.135 diopters for LAL and LDD minus Control IOL. Keeping the subtraction order explicit matters: reversing the order would reverse the sign, even though the underlying separation between group means would be the same.

The mean difference describes a group-level contrast. It does not describe the experience of every participant, and it does not show whether outcomes overlap between groups. The standard deviation gives information about the spread of measurements around each group mean. The reported standard deviations are 0.213 diopters for LAL and LDD and 0.265 diopters for Control IOL. A standard deviation is different from a standard error: the former describes variation among measurements, while the latter describes uncertainty in an estimated quantity.

How should the confidence interval be understood?

A confidence interval is a range of values compatible with the observed data under a specified statistical procedure and its assumptions. In repeated use of a procedure, intervals constructed in this way have a stated coverage property. It is not correct to interpret a single confidence interval as assigning a probability to the true effect after the data have been observed. The reported interval for this mean difference is -0.182 to -0.088 diopters when expressed to three decimal places.

The interval communicates both direction and precision. Because its reported limits are negative, it excludes zero at the interval’s stated confidence level. The exact confidence level and interval-construction method are not reported in the registry record. A confidence interval does not establish that the size of a difference is important for patients; that judgment would require a relevant clinical threshold, which is not reported.

What does the p-value add?

The registry reports an unadjusted p-value of < 0.001. In general, a p-value measures how incompatible the observed data, or data more extreme, are with a specified null model if that model and the analysis assumptions hold. It is not the probability that the null hypothesis is true, and it does not indicate the magnitude of the effect. The estimate and confidence interval are needed to understand direction and size; the p-value alone cannot provide that interpretation.

“Unadjusted” indicates that the reported p-value is not presented as adjusted for multiplicity. The record does not state which exact statistical test generated it or give a broader statistical analysis plan. It also does not explain whether any adjustment for covariates was used. Accordingly, the reported p-value should be read as the posted unadjusted significance result, not as a complete description of all planned analyses.

Why do allocation and masking matter?

Randomization aims to make assigned groups comparable, on average, with respect to factors that might affect the outcome. It reduces the risk that assignment is systematically related to such factors. Randomization does not guarantee perfect balance in a particular study, and it cannot address every source of bias after assignment. The record identifies allocation as randomized but does not describe the allocation procedure or concealment.

Masking can reduce the potential for expectations or knowledge of assignment to influence some aspects of study conduct or outcome assessment. The record labels masking as single but does not identify who was masked. It therefore does not allow a reader to assess which parts of treatment delivery, follow-up, or measurement were protected from knowledge of assignment.

What is not specified about the analysis?

The primary outcome is a continuous measure, and the registry reports means and standard deviations for both groups, along with a mean difference, confidence interval, and p-value. The exact test, model, confidence level, handling of missing values, and analysis population are not reported in the registry record. It is also not reported whether the analysis included baseline adjustment or other covariates. These details can affect interpretation and reproducibility, so the summary statistics should not be treated as a substitute for a full statistical analysis plan.

The record lists seven outcome measures and four analyses. It also names two secondary outcomes: rate of endothelial cell density loss and rate of retinal findings. The available record does not explain how those outcomes relate to the count of analyses, which outcomes were included in each analysis, or whether the inferential results were adjusted for multiple testing. Multiple testing is a general concern because examining several outcomes or analyses can increase the chance of at least one apparently unusual result under a collection of null hypotheses. Whether and how that concern was addressed for this study is not reported.

The group summaries do not reveal how the outcome is distributed, whether there are influential observations, or how many measurements were missing at the primary time point. A mean-and-standard-deviation summary is most informative when interpreted alongside the analysis assumptions and outcome distribution. The registry record does not provide the participant-level information needed to assess those features. These limitations do not change the posted numerical result; they define what can and cannot be inferred from the record.

10. Confidence Intervals and Precision

The reported mean difference is -0.135 diopters, with a confidence interval from -0.182 to -0.088 diopters when the limits are written to three decimal places. The interval gives a range of plausible values for the group difference under the method’s assumptions. Its position entirely below zero indicates that the posted interval does not include no difference. The registry record does not report the confidence level or the method used to construct the interval.

Precision concerns how narrowly an estimate is determined, not whether it is clinically important. A narrower interval indicates less statistical uncertainty about the estimated difference than a wider interval, but even a precise estimate can be clinically unimportant. Conversely, an imprecise estimate can include values that would matter in either direction. The registry record does not give a clinical threshold for interpreting the magnitude of the MRSE contrast.

The reported standard deviations, 0.213 diopters for LAL and LDD and 0.265 diopters for Control IOL, describe variation in individual measurements within each group. They do not substitute for the confidence interval around the between-group difference. The record does not provide individual-level distributions, missing-data counts for the primary endpoint, or a breakdown by analysis population, all of which would add context for evaluating precision.

The unadjusted p-value is < 0.001, but a small p-value does not mean that the estimate is exact. The confidence interval is the more direct summary of uncertainty about the magnitude of the difference. Both should be interpreted in light of the endpoint, follow-up time, and unreported analysis details.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total event counts. They are illustrations based on the observed effect, rather than a report of the trial’s original sample-size calculation. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set as a stated fraction of the observed effect.

For the illustration using 100% of the observed effect, the registry-based planning values are 47 participants per arm for 80% power and 62 participants per arm for 90% power. For planning at 75% of the observed effect, the values are 83 participants per arm for 80% power and 110 participants per arm for 90% power. For planning at 50% of the observed effect, the values are 185 participants per arm for 80% power and 248 participants per arm for 90% power.

In general, power is the probability that a specified statistical procedure will reject a null hypothesis under a particular assumed effect and other design assumptions. The 80% and 90% columns represent different target probabilities of detecting the assumed effect under those assumptions. The higher target generally requires more participants. Likewise, smaller effects are harder to distinguish from random variation and require more participants than larger effects under otherwise comparable assumptions.

These values are not observed power. They are planning illustrations based on the observed effect and stated assumptions. The original trial design assumptions, including the effect size used when enrollment was planned, are not reported in the registry record.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -0.135; pooled standard deviation σ = 0.231.
2. n = 2 × (1.96 + 0.842)² × 0.231² / -0.135² = 46.1, rounded up to 47 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -0.135                      # observed difference in means
sigma <- 0.231452962141794                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(5202808)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 47 (80% power), 62 (90% power)
 75% of observed effect: n per arm = 83 (80% power), 110 (90% power)
 50% of observed effect: n per arm = 185 (80% power), 248 (90% power)
power.t.test: 47.1 
Simulated power at n = 47 per arm: 0.793 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists seven outcome measures and four analyses. It names rate of endothelial cell density loss and rate of retinal findings as secondary outcomes. The MRSE comparison is identified as the primary outcome measure, while the study’s stated primary objective describes a comparison for safety outcomes. The record does not explain how these descriptions relate to the full analysis plan.

When several outcomes or analyses are examined, multiplicity can affect how often results appear statistically significant by chance across the collection of tests. Statistical approaches may address this through prespecified hierarchies, adjustments to significance levels, or other strategies. These are general options, not statements about this study. Whether a multiplicity adjustment was planned or used is not reported in the registry record. The posted p-value for the MRSE comparison is identified as unadjusted.

The record does not describe missing-data methods for the primary outcome or the secondary outcomes. It does not state how participants without a measurement at postoperative month 6 were handled, whether any values were imputed, or whether analyses used complete observations only. It also does not report an analysis population definition such as intention-to-treat or per-protocol. The primary outcome counts and safety at-risk counts differ, but the reasons for those differences are not given.

The record does not provide a detailed statistical analysis plan, the exact test used for the primary endpoint, or any covariate-adjustment details. It is also not reported whether outcomes or analyses were selected or revised after data collection began. Without these details, the posted result can be described as a group comparison with an unadjusted p-value, but it cannot be fully evaluated against prespecified analysis decisions or the treatment of incomplete data.

These omissions do not establish that missing-data or multiplicity methods were absent; they mean that the registry record does not report them. A complete interpretation of the overall evidence would require those analysis details alongside results for the secondary outcomes and other posted measures.

14. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: secondary surgical intervention: intraocular lens exchange (0.6%), inpatient hospitalization for ventral hernia repair surgery (0.6%), inpatient hospitalization due to pneumonia (0.6%), secondary surgical intervention: iris repositioning following prolapse (0.3%), secondary surgical intervention: study eye, selective laser trabeculoplasty (0.3%).

The safety record gives at-risk counts of 335 for the LAL and LDD group and 165 for the Control IOL group. It reports 7 participants with serious adverse events in the LAL and LDD group and 2 in the Control IOL group. For other adverse events, the record reports 71 affected in the LAL and LDD group and 26 in the Control IOL group. Deaths are reported as 0 in each group.

The registry’s serious-event terms include secondary surgical intervention for intraocular lens exchange at 0.6%, inpatient hospitalization for ventral hernia repair surgery at 0.6%, and inpatient hospitalization due to pneumonia at 0.6%. Other listed terms are secondary surgical intervention for iris repositioning following prolapse at 0.3%, secondary surgical intervention in the study eye for selective laser trabeculoplasty at 0.3%, and secondary surgical intervention for non-study eye intraocular lens exchange at 0.3%.

These figures describe the safety entries in the registry. They do not establish that every listed event was caused by the study device, and the record does not provide event timing, severity grading beyond the serious classification, or a comparative statistical analysis of safety. Counts and at-risk denominators should be read as reported, without assuming that the endpoint and safety populations are identical.

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

The posted primary result describes a mean MRSE of 0.21 diopters in the LAL and LDD group and 0.345 diopters in the Control IOL group at postoperative month 6. The estimated difference is -0.135 diopters for LAL and LDD minus Control IOL, with a confidence interval from -0.182 to -0.088 diopters when expressed to three decimal places. The unadjusted p-value is < 0.001. Together, these statistics describe a negative group-level difference on the MRSE scale, with the reported interval excluding zero.

That result does not establish that the difference is clinically important. The registry does not provide a threshold for clinical importance or explain how the word “Absolute” in the endpoint title is defined. Statistical evidence about a difference and clinical interpretation of its magnitude are separate questions. The mean also does not indicate the result for any one participant or describe the full distribution of measurements within each group.

The MRSE result is not a complete assessment of safety. Although the study objective refers to safety and the record includes adverse-event counts and event terms, those entries do not establish causation or provide a full comparative safety analysis. The named secondary outcomes are rate of endothelial cell density loss and rate of retinal findings; their results are not included in the information summarized for this comparison.

The result applies to the specified endpoint and postoperative month 6. It does not establish what the groups’ outcomes were at other times or on outcomes that are not described. The study is recorded as randomized and single-masked, but the masked party and several design and analysis details are not reported. Those gaps limit assessment of bias, missing data, and the wider analysis plan.

Accordingly, the posted statistics support a focused description of the observed MRSE comparison and its uncertainty. They do not, on their own, support a broader claim about overall device performance, every safety outcome, or individual treatment decisions.

16. Why This Trial Matters Statistically

This trial illustrates why statistical interpretation should distinguish an estimate, its uncertainty, and its clinical meaning. The mean difference of -0.135 diopters gives a direction and magnitude on the endpoint scale, while the confidence interval from -0.182 to -0.088 diopters describes uncertainty under the interval method’s assumptions. The unadjusted p-value of < 0.001 addresses compatibility with a null model, not the practical importance of the difference.

The endpoint is continuous, so the means are useful summaries, but they do not show the full range or shape of individual measurements. The reported group standard deviations add information about within-group spread. Considering both the spread and the interval around the contrast helps prevent a common interpretive error: treating a statistically clear difference as automatically important to patients or interpreting group averages as individual outcomes.

The record also highlights the importance of consistency between study objectives and outcome descriptions. Its stated primary objective refers to safety outcomes, while the named primary measure compares MRSE. Without further explanation, readers should keep those concepts distinct rather than treating the refractive result as a substitute for a safety analysis.

Finally, the registry gives limited detail about analysis populations, missing data, multiplicity, and the original sample-size rationale. Those details matter because they clarify which participants contributed to each estimate and how the statistical conclusions were planned. The result remains interpretable as a posted month-6 group comparison, but a complete appraisal requires attention to the limits of the record and to the distinction between reported results and unreported analysis choices.

17. 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 features of this specific registry record limit interpretation. The arm descriptions are empty, so details of the device use and control condition beyond their names are not available. Masking is recorded as single, but the identity of the masked party is not reported. The randomization method and allocation concealment are also not described.

The primary objective is framed as a comparison for safety outcomes, whereas the named primary outcome measure is the month-6 MRSE comparison. The record does not explain this difference in emphasis. The secondary outcomes are identified, but their results and timeframes are not included in the information summarized for this analysis.

The record reports different counts for the primary outcome and safety risk groups: 332 and 164 for the MRSE comparison, and 335 and 165 at risk for safety. It does not explain the differences or define the analysis populations. It also does not report the number of missing month-6 measurements, how missing data were handled, or whether the primary analysis followed an intention-to-treat approach.

The statistical test, confidence level, interval method, covariate adjustment, and multiplicity strategy are not reported. Nor are participant characteristics, individual-level data, or a clinical threshold for interpreting the size of an MRSE difference. The registry gives an enrollment of 500, but the original sample-size assumptions and justification are not reported. These limitations constrain evaluation of generalizability, precision, and the analysis plan without changing the numerical results that are posted.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: RxSight Light Adjustable Lens and Light Delivery Device New Enrollment Study — NCT05202808.
• Registry record last updated 2025-04-20; status last verified 2025-04.
• Results first posted 2025-04-20.
• 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.

21. Record Summary

The registry record identifies NCT05202808 as a completed, randomized, single-masked, parallel-group post-approval study of the Light Adjustable Lens and Light Delivery Device compared with a Control IOL. It lists aphakia and cataract as conditions, an enrollment of 500, a start date of 2021-12-03, and a primary completion date of 2024-09-11.

The named primary outcome is mean Absolute Manifest Refraction Spherical Equivalent at postoperative month 6, measured in diopters. The posted means are 0.21 for LAL and LDD and 0.345 for Control IOL. The mean difference is -0.135 diopters, with a reported confidence interval from -0.182 to -0.088 diopters when written to three decimal places and an unadjusted p-value of < 0.001.

The record also names rate of endothelial cell density loss and rate of retinal findings as secondary outcomes. Safety entries report serious and other adverse events, with no deaths recorded in either group. Details about analysis populations, missing data, multiplicity, masking, and the original sample-size rationale are not reported in the registry record.