IOL Position and Refractive Change After Nd:YAG Laser Posterior Capsulotomy

NCT07802145 | Not Yet Recruiting

• 1 other identifier: MA15-EK-26-141
• Study Type: observational
• Target: 80
• Locations: 1 country
• Sites: 1

Brief Summary

After cataract surgery, the thin natural membrane that holds the artificial lens in place can slowly turn cloudy. This is called posterior capsule opacification. It makes vision blurry and can cause glare. The standard treatment is a short, painless laser procedure called Nd:YAG capsulotomy, which opens a small clear window in the cloudy membrane. Opening this membrane changes the support structure around the artificial lens. Eye doctors do not agree on what happens next. Some studies found that the lens shifts slightly backward in the eye after the laser treatment, some found that it shifts forward, and some found no movement at all. It is also unclear whether such a small shift changes how well a person sees or the strength of their glasses. One reason for these mixed results may be that each study used a different imaging device, and these devices measure the depth of the front chamber of the eye in different ways. This study measures the position of the artificial lens in the same eye with three different imaging devices, before and after the laser treatment. The devices are called IOLMaster 700, CASIA2, and Pentacam AXL. All three take detailed pictures of the front of the eye without touching it. The study team wants to find out whether the artificial lens moves after the laser treatment, how much it moves, whether any movement changes vision or the glasses prescription, and whether the three devices give matching results. Who can take part People who had cataract surgery at least three months ago, who now have a cloudy membrane behind the artificial lens, and whose eye doctor has already decided that the laser treatment is needed. What taking part involves Taking part does not change the laser treatment in any way. The decision to perform the treatment, the technique, and the laser settings are made by the treating doctor for medical reasons and are not influenced by the study. The study only adds extra measurements before and after the treatment. There are three study visits:

• Visit 1, on the day of the laser treatment and before the laser is used. The extra measurements take about 30 to 45 minutes.
• Visit 2, about one week after the treatment. The extra measurements take about 15 to 20 minutes.
• Visit 3, about one month after the treatment. The extra measurements take about 30 to 45 minutes. At each visit the study team checks how well you can see, measures the strength of glasses that gives you the sharpest vision, examines your eye with a slit lamp, measures the pressure inside your eye, and takes images with the imaging devices. All of these are standard eye examinations used in everyday clinical practice. Nothing is inserted into the eye, and there are no injections, no medicines, and no radiation. Drops to widen the pupil are not needed for the study. Taking part is voluntary. You can stop at any time, without giving a reason and without any disadvantage for your medical care. Your laser treatment and all routine follow-up visits go ahead either way. There is no payment for taking part, and taking part brings no direct medical benefit. However, the detailed examination may reveal something that would not be noticed during routine follow-up, such as raised eye pressure. If this happens, you will be told and any necessary care will be arranged as part of your normal treatment at no extra cost. Study data are stored under a study code instead of your name.

Conditions

Posterior Capsule Opacification; Pseudophakia; Refractive Errors

Keywords

Nd:YAG laser capsulotomy; Posterior capsulotomy; Anterior chamber depth; Effective lens position; Intraocular lens tilt; Intraocular lens decentration; Swept-source optical coherence tomography; Scheimpflug tomography; Optical biometry; Inter-device agreement; Refractive shift; Toric intraocular lens rotation

Outcome Measures

Primary Outcomes (1)

• Change in anterior chamber depth (ACD) measured by anterior segment swept-source OCT

  ACD in millimetres, measured from the posterior corneal surface to the anterior IOL surface by automated CASIA2 segmentation. The change is calculated as ACD after capsulotomy minus ACD before capsulotomy. Positive values indicate posterior IOL displacement, negative values anterior displacement. Reported as mean change with standard deviation and 95% confidence interval, together with the proportion of eyes exceeding the pre-specified clinical relevance threshold of 0.05 mm in absolute value.

  Baseline (immediately before capsulotomy) and 1 month (plus or minus 7 days) after capsulotomy

Secondary Outcomes (15)

• Change in IOL tilt measured by anterior segment swept-source OCT

  Baseline and 1 month after capsulotomy

• Change in IOL decentration measured by anterior segment swept-source OCT

  Baseline and 1 month after capsulotomy

• Change in spherical equivalent from standardized manifest refraction

  Baseline, 1 week and 1 month after capsulotomy

• Proportion of eyes with a clinically relevant refractive shift

  1 week and 1 month after capsulotomy

• Change in refractive cylinder magnitude and axis

  Baseline, 1 week and 1 month after capsulotomy

Study Arms (1)

Pseudophakic Eyes Undergoing Nd:YAG Laser Posterior Capsulotomy

Pseudophakic eyes with visually significant posterior capsule opacification for which Nd:YAG laser posterior capsulotomy is clinically indicated independently of the study. Each eye is assessed with a standardized multi-device anterior segment protocol immediately before the routine procedure and at one week and one month afterwards, and serves as its own control in a paired within-eye comparison.

Procedure: Nd:YAG laser posterior capsulotomy; Diagnostic Test: Anterior segment swept-source OCT; Diagnostic Test: Swept-source optical biometry; Diagnostic Test: Scheimpflug-based anterior segment tomography; Diagnostic Test: Subjective manifest refraction

Interventions

Nd:YAG laser posterior capsulotomy PROCEDURE

Routine Nd:YAG laser posterior capsulotomy performed for visually significant posterior capsule opacification according to the department's standard clinical protocol. Indication, technique, energy settings and capsulotomy size are determined by the treating ophthalmologist and are not modified by the study. Procedural parameters are documented for analysis.

Pseudophakic Eyes Undergoing Nd:YAG Laser Posterior Capsulotomy

Swept-source optical biometry DIAGNOSTIC_TEST

on-contact optical biometry providing anterior chamber depth, keratometry, total keratometry, axial length, central corneal thickness, white-to-white and pupillometry.

Pseudophakic Eyes Undergoing Nd:YAG Laser Posterior Capsulotomy

Scheimpflug-based anterior segment tomography DIAGNOSTIC_TEST

Scheimpflug-based anterior segment tomography providing anterior chamber depth, SimK, total corneal refractive power, true net power, posterior keratometry, pachymetry mapping, corneal irregularity indices, chamber angle and volume, and axial length.

Pseudophakic Eyes Undergoing Nd:YAG Laser Posterior Capsulotomy

Anterior segment swept-source OCT DIAGNOSTIC_TEST

Non-contact anterior segment optical coherence tomography providing anterior chamber depth, anterior chamber angle and volume, automated three-dimensional IOL tilt and decentration, corneal tomography, pachymetry and pupil parameters. Primary device for the primary outcome measure.

Pseudophakic Eyes Undergoing Nd:YAG Laser Posterior Capsulotomy

Subjective manifest refraction DIAGNOSTIC_TEST

Autorefraction as starting value followed by subjective manifest refraction with Jackson cross-cylinder refinement, yielding sphere, cylinder, axis and spherical equivalent, plus uncorrected and best-corrected distance visual acuity in logMAR. The refractionist is masked to previous refraction values at the post-capsulotomy visits.

Pseudophakic Eyes Undergoing Nd:YAG Laser Posterior Capsulotomy

Eligibility Criteria

• Age: 18 Years - 100 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Consecutive pseudophakic patients presenting to the Department of Ophthalmology, Klinik Hietzing, Vienna, Austria, with visually significant posterior capsule opacification for which Nd:YAG laser posterior capsulotomy is clinically indicated. Patients are identified through the routine clinical workflow: the cataract follow-up clinic, referrals from external ophthalmologists, and self-presentation with visual complaints consistent with posterior capsule opacification. Enrolment is consecutive and unselected with respect to IOL model, axial length, time since cataract surgery and morphology of the opacification, so that the cohort reflects the general population of pseudophakic eyes undergoing capsulotomy at the study centre. The decision to perform the capsulotomy is made independently of the study.

You may qualify if:

• Pseudophakic eye with visually significant posterior capsule opacification for which Nd:YAG laser posterior capsulotomy is clinically indicated, defined as a subjective visual complaint attributable to the opacification (reduced visual acuity, glare or reduced contrast) together with objectively documented opacification on slit-lamp examination
• Previous uneventful phacoemulsification with in-the-bag implantation of a posterior chamber intraocular lens; no restriction on IOL model
• At least 3 months between the cataract surgery and the baseline study visit
• Age 18 years or older at enrolment
• Able to cooperate with the multi-device measurement protocol, including fixation for all three imaging devices and standardized subjective manifest refraction with Jackson cross-cylinder refinement
• Written informed consent

You may not qualify if:

• Complicated cataract surgery, including posterior capsule rupture, vitreous loss, zonular dialysis, sulcus intraocular lens placement, anterior vitrectomy, or any other deviation from standard in-the-bag implantation
• Previous intraocular lens exchange, repositioning, or secondary piggyback implantation
• Previous Nd:YAG posterior capsulotomy of the study eye
• Previous corneal refractive surgery of the study eye
• Active anterior segment inflammation at the baseline visit
• Clinically significant corneal pathology precluding reliable keratometry, including corneal oedema, band keratopathy, central corneal scarring, and Fuchs endothelial corneal dystrophy grade 3 or 4 with clinically evident oedema; grades 1 and 2 without oedema are eligible
• Known intraocular lens instability before capsulotomy, including subluxation, decentration estimated above 1.0 mm, or pseudophacodonesis
• Cognitive or physical limitations precluding standardized subjective manifest refraction

Sponsors & Collaborators

• Vienna Hospital Association: lead

Study Sites (1)

Augenabteilung, Klinik Hietzing, Wiener Gesundheitsverbund

Vienna, State of Vienna, 1130, Austria

Location

MeSH Terms

Conditions

Pseudophakia; Refractive Errors

Condition Hierarchy (Ancestors)

Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Eye Diseases

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Head of the Department

Study Record Dates

• First Submitted: August 30, 2026
• First Posted: September 3, 2026
• Study Start: September 1, 2026
• Primary Completion (Estimated): August 1, 2027
• Study Completion (Estimated): August 1, 2027
• Last Updated: September 3, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

AU (1)