Three-Dimensional Assessments of Intraocular Lens Stability With High-Speed Swept-Source Optical Coherence Tomography

Capsular Tension Ring Implantation for Intraocular Lens Decentration and Tilt in Highly Myopic Eyes: A Randomized Clinical Trial

Importance

Capsular tension rings (CTRs) can support weak zonules and inhibit capsular shrinkage, thus potentially reducing intraocular lens (IOL) decentration and tilt. However, it has been debated whether CTRs can reduce IOL decentration and tilt in highly myopic eyes and whether CTR implantation is necessary for all highly myopic eyes.

Objective

To evaluate the influence of CTR implantation on IOL decentration and tilt in highly myopic eyes.

Design, Setting, and Participants

This randomized clinical trial was conducted between November 2021 and September 2023 at the Zhongshan Ophthalmic Center, Guangzhou, China. Patients with cataract and an axial length (AL) of 26 mm or longer were enrolled.

Interventions

Participants were stratified into 3 groups based on the AL (stratum 1, 26 mm ≤ AL <28 mm; stratum 2, 28 mm ≤ AL <30mm; stratum 3, AL ≥30 mm), and further randomly assigned to the CTR group (a C-loop IOL combined with a CTR) or the control group (only a C-loop IOL) within each stratum.

Main Outcomes and Measures

IOL decentration at 3 months after cataract surgery was evaluated using anterior segment optical coherence tomography.

Results

A total of 186 eyes of 186 participants (mean [SD] age, 57.3 [10.9] years; 118 female [63.4%]) were randomized into the CTR group (93 [50%]) or control group (93 [50%]), with 87 eyes (93.6%) and 92 eyes (98.9%) completing follow-up at 3 months, respectively. The CTR group showed smaller IOL decentration (0.19 mm vs 0.23 mm; difference, -0.04 mm; 95% CI, -0.07 to -0.01 mm; P = .02) and tilt at 3 months, and lower proportions of clinically significant IOL decentration (≥0.4 mm) and tilt (≥7°) at 3 months compared with the control group. Similar results were only found in eyes with an AL of 30 mm or longer (IOL decentration: 0.20 mm vs 0.28 mm; difference, -0.08 mm; 95% CI, -0.14 to -0.02 mm; P = .01). Additionally, the CTR group showed a smaller change in IOL decentration from 1 week to 3 months, higher prediction accuracy, and better visual quality and patient satisfaction in this stratum. No differences were observed between the CTR and control groups in eyes with an AL less than 30 mm.

Conclusions and Relevance

CTR implantation reduced C-loop IOL decentration and tilt, increased position stability, and improved visual quality in eyes with an AL of 30 mm or longer. These findings support use of CTR implantation in eyes with an AL of 30 mm or longer and implanted with C-loop IOLs.

Trial Registration

ClinicalTrials.gov Identifier: NCT05161520.

Repeatability of Pentacam-derived intraocular lens decentration measurements and the level of agreement with OPD-Scan III: A prospective observational case series

PURPOSE

This study aimed to assess the repeatability of intraocular lens (IOL) decentration measurements obtained through Pentacam, based on corneal topographic axis (CTA) and pupillary axis (PA), and to evaluate the level of agreement between Pentacam and OPD-Scan III devices in measuring IOL decentration.

METHODS

In this prospective observational case series, three measurements were performed with Pentacam to evaluate the repeatability of the measurements. The analysis included the calculation of the mean and standard deviations (SD), conducting a repeated measures analysis of variance (rANOVA), and determining an intraclass correlation coefficient (ICC) to assess the repeatability of the measurements. Moreover, Bland-Altman analysis was employed to assess the agreement between Pentacam and OPD-Scan III devices in measuring IOL decentration. IOL decentration measurements were obtained with respect to both CTA and PA.

RESULTS

A total of 40 eyes from 40 patients were analyzed. The rANOVA revealed no significant difference among three consecutive measurements of IOL decentration obtained with Pentacam. The mean SD of all parameters ranged from 0.04 mm to 0.07 mm. With CTA as the reference axis, the ICC values for Pentacam measurements of IOL decentration were 0.82 mm for the X-axis, 0.76 mm for the Y-axis, and 0.82 mm for spatial distance. When using PA as the reference axis, the corresponding ICC values were 0.87, 0.89, and 0.77, respectively. The 95% limits of agreement for all IOL decentration measurements were wide when comparing Pentacam and OPD-Scan III.

CONCLUSIONS

Pentacam demonstrated high repeatability in measuring IOL decentration with respect to both CTA and PA. However, due to poor agreement between Pentacam and OPD-Scan III measurements, caution should be exercised when using data interchangeably between the two devices.

Intraocular lens tilt and decentration after cataract surgery with and without primary posterior continuous curvilinear capsulorhexis

PURPOSE

To evaluate intraocular lens (IOL) tilt and decentration and their effects on higher-order aberrations (HOAs) after cataract surgery with and without primary posterior continuous curvilinear capsulorhexis (PPCCC).

SETTING

Fujian Provincial Hospital, Fujian, China.

DESIGN

Prospective, intraindividual, randomized, comparative clinical trial.

METHODS

64 eyes of 32 patients with age-related cataract who underwent bilateral cataract surgery and IOL implantation were enrolled in this study. In randomized order, all patients had phacoemulsification cataract surgery with PPCCC in 1 eye (PPCCC group) and routine cataract surgery in the contralateral eye (NPCCC group). IOL decentration, tilt, HOAs, modulation transfer function, and point spread function were measured at 1 day, 1 week, 1 month, and 3 months after surgery using OPD-Scan III.

RESULTS

52 eyes of 26 patients were available for analysis. The mean overall decentration in the NPCCC group was significantly higher than in the PPCCC group at 3 months (0.302 ± 0.157 mm vs 0.187 ± 0.099 mm, P < .001). Under 3 mm pupil, internal spherical aberration (SA) 1 day after surgery and coma 1 week after surgery were lower in the PPCCC group compared with the NPCCC group (0.15 ± 0.10 μm vs 0.30 ± 0.21 μm, P < .001, and 0.34 ± 0.18 μm vs 0.47 ± 0.31 μm, P = .03, respectively). IOL decentration was significantly correlated with ocular and internal coma, ocular and internal SA, and internal HOAs at 5 mm pupil ( R = 0.083 and R = 0.099, R = 0.650 and R = 0.613, and R = 0.418, respectively, all P < .01).

CONCLUSIONS

Less IOL decentration was observed in the PPCCC group at 3 months after surgery, indicating that PPCCC may result in better IOL centrality.

Predicting the risk of clinically significant intraocular lens tilt and decentration in vitrectomized eyes

PURPOSE

To identify predictors and develop a prognostic nomogram for clinically significant intraocular lens (IOL) tilt and decentration in vitrectomized eyes.

SETTING

Zhongshan ophthalmic center, Guangzhou, China.

DESIGN

Prospective observational study.

METHODS

Patients with previous pars plana vitrectomy who underwent phacoemulsification with IOL implantation were enrolled in this study. The tilt and decentration of the lens and IOL were assessed by a swept-source anterior segment optical coherence tomography (CASIA2). Multiple logistic regression analysis and prognostic nomogram models were used to explore factors associated with clinically significant IOL tilt and decentration (defined as tilt ≥7 degrees and decentration ≥0.4 mm).

RESULTS

375 patients (375 eyes) with a mean age of 56.1 ± 9.81 years were included. Lens tilt (odds ratio [OR] = 1.44), lens decentration (OR = 1.74), lens diameter (OR = 0.49), and hydrophilic IOL (OR = 2.36) were associated with IOL tilt over 7 degrees (all P &amp;lt; .05). Lens tilt (OR = 1.24), lens decentration (OR = 2.30), and incomplete capsulorhexis-IOL overlap (OR = 2.44) increased the risk of IOL decentration over 0.4 mm (all P &amp;lt; .05). Preoperative lens tilt together with lens decentration was identified as the strongest predictor of incident clinically significant IOL tilt (area under the curve [AUC] = 0.82, 95% CI, 0.76-0.88) and decentration (AUC: 0.84, 95% CI, 0.78-0.89), and the nomogram was constructed accordingly.

CONCLUSIONS

The tilt and decentration of the crystalline lens, hydrophilic IOL, and incomplete capsulorhexis-IOL overlap were risk factors for clinically significant IOL misalignment. Clinicians could use a prognostic nomogram model based on the preoperative lens position to make a strategy for higher-risk patients.

Three-dimensional assessment of posterior capsule-intraocular lens interaction with and without primary posterior capsulorrhexis: an intraindividual randomized trial

PURPOSE

To assess the morphologic and clinical features of posterior capsule-intraocular lens (IOL) interaction following cataract surgery with and without primary posterior continuous curvilinear capsulorrhexis (PPCCC) at a three-dimensional (3-D) level using Scheimpflug imaging.

METHODS

This prospective intraindividual randomized comparative study comprised 56 patients (112 eyes) with age-related cataract who had bilateral cataract surgery and hydrophobic acrylic IOLs implantation. In randomized order, cataract surgery with PPCCC was performed in 1 eye (PPCCC group), and the posterior capsule was left intact in the fellow eye (NPCCC group). Scheimpflug imaging containing 25 images distributed in 360° was taken 1 day, 1 week, 1 month, and 3 months postoperatively.

RESULTS

46 patients completed 3 months follow-up. Posterior capsule-IOL interaction can be morphologically classified into two types including complete adhesion and floppy shape in PPCCC group, and six types including full area wave, full area flat, concentric ring wave, concentric ring flat, sector, and complete adhesion in NPCCC group. The adhesion index (AI), defined as the proportion of complete adhesion of posterior capsule-IOL in 25 cross-section tomograms, was 0.45 ± 0.45, 0.79 ± 0.37, 0.92 ± 0.26 and 1.00 ± 0.00 in PPCCC group, while 0.05 ± 0.18, 0.41 ± 0.47, 0.87 ± 0.34, and 0.96 ± 0.21 in NPCCC group at 1 day, 1 week, 1 month and 3 months postoperatively, respectively (p = 0.001, 0.001, 0.338 and 0.151).

CONCLUSIONS

3-D Scheimpflug imaging was favorable in observing of posterior capsule-IOL interaction. Faster posterior capsule adhesion to the IOL was found in PPCCC group than in NPCCC group.

Determining the Theoretical Effective Lens Position of Thick Intraocular Lenses for Machine Learning-Based IOL Power Calculation and Simulation

Purpose

To describe a formula to back-calculate the theoretical position of the principal object plane of an intraocular lens (IOL), as well as the theoretical anatomic position in a thick lens eye model. A study was conducted to ascertain the impact of variations in design and IOL power, on the refractive outcomes of cataract surgery.

Methods

A schematic eye model was designed and manipulated to reflect changes in the anterior and posterior radii of an IOL, while keeping the central thickness and paraxial powers static. Modifications of the shape factor (X) of the IOL affects the thick lens estimated effective lens position (ELP). Corresponding postoperative spherical equivalent (SE) were computed for different IOL powers (-5 diopters [D], 5 D, 15 D, 25 D, and 35 D) with X ranging from -1 to +1 by 0.1.

Results

The impact of the thick lens estimated effective lens position shift on postoperative refraction was highly dependent on the optical power of the IOL and its thickness. Design modifications could theoretically induce postoperative refraction variations between approximately 0.50 and 3.0 D, for implant powers ranging from 15 D to 35 D.

Conclusions

This work could be of interest for researchers involved in the design of IOL power calculation formulas. The importance of IOL geometry in refractive outcomes, especially for short eyes, should challenge the fact that these data are not usually published by IOL manufacturers.

Translational Relevance

The back-calculation of the estimated effective lens position is central to intraocular lens calculation formulas, especially for artificial intelligence-based optical formulas, where the algorithm can be trained to predict this value.

Effect of Intraocular Lens Tilt and Decentration on Visual Acuity, Dysphotopsia and Wavefront Aberrations

Tilt and decentration of intraocular lenses (IOL) may occur secondary to a complicated cataract surgery or following an uneventful phacoemulsification. Although up to 2–3° tilt and a 0.2–0.3 mm decentration are common and clinically unnoticed for any design of IOL, larger extent of tilt and decentration has a negative impact on the optical performance and subsequently, the patients’ satisfaction. This negative impact does not affect various types of IOLs equally. In this paper we review the methods of measuring IOL tilt and decentration and focus on the effect of IOL tilt and decentration on visual function, in particular visual acuity, dysphotopsia, and wavefront aberrations. Our review found that the methods to measure the IOL displacement have significantly evolved and the available studies have employed different methods in their measurement, while comparability of these methods is questionable. There has been no universal reference point and axis to measure the IOL displacement between different studies. A remarkably high variety and brands of IOLs are used in various studies and occasionally, opposite results are noticed when two different brands of a same design were compared against another IOL design in two studies. We conclude that <5° of inferotemporal tilt is common in both crystalline lenses and IOLs with a correlation between pre- and postoperative lens tilt. IOL tilt has been noticed more frequently with scleral fixated compared with in-the-bag IOLs. IOL decentration has a greater impact than tilt on reduction of visual acuity. There was no correlation between IOL tilt and decentration and dysphotopsia. The advantages of aspheric IOLs are lost when decentration is >0.5 mm. The effect of IOL displacement on visual function is more pronounced in aberration correcting IOLs compared to spherical and standard non-aberration correcting aspherical IOLs and in multifocal versus monofocal IOLs. Internal coma has been frequently associated with IOL tilt and decentration, and this increases with pupil size. There is no correlation between spherical aberration and IOL tilt or decentration. Although IOL tilt produces significant impact on visual outcome in toric IOLs, these lenses are more sensitive to rotation compared to tilt.