Geometry of Acrylic, Hydrophobic IOLs and Changes in Haptic-Capsular Bag Relationship According to Compression and Different Well Diameters: A Bench Study Using Computed Tomography

Blue-Light Filtering Monofocal Intraocular Lenses: A Study on Optical Function and Tolerance to Misalignment

PURPOSE

To investigate the optical performance and tolerance to misalignment of blue-light filtering monofocal intraocular lenses (IOLs).

METHODS

The optical properties of two monofocal IOLs featuring yellow chromophores, CT Lucia 621 PY (Carl Zeiss Meditec AG) and Clareon CNA0T0 (Alcon Laboratories, Inc), were assessed in monochromatic and polychromatic light while introducing spherical aberration (SA). Optical quality metrics derived from the modulation transfer function were assessed after optimal IOL centration at 3- and 4.5-mm pupils. In addition, each IOL's tolerance to misalignment was examined by inducing up to 1 mm of decentration and the effect of tilting it by 5 degrees at 3 mm.

RESULTS

The IOLs' resolution and contrast, while tested using a 3-mm aperture and an SA-neutral corneal model, indicated the CT Lucia 621 PY had a slightly higher modulation transfer function (MTF) at 50 lp/mm than the CNA0T0 under monochromatic conditions (0.77 vs 0.69). On introducing SA with (0.49 vs 0.40) and without (0.75 vs. 0.70) chromatic aberration, the CT Lucia 621 PY maintained its minimally better performance. When assessed with a 4.5-mm aperture in monochromatic light, the CT Lucia 621 PY displayed improved MTF with aberration-free cornea (0.71 vs 0.40) but performed worse after introducing SA (0.44 vs 0.62). However, both lenses achieved comparable MTF values under spherical and chromatic aberrations (0.28 vs 0.27). The IOL misalignment test revealed a better tolerance to tilt and decentration of the CT Lucia 621 PY across all conditions.

CONCLUSIONS

The CT Lucia 621 PY and CNA0T0 showed similar optical quality in different situations, with equal simulated distance visual acuity for both models. However, the CT Lucia 621 PY's aspheric design offers an advantage when dealing with often imperfect physiological conditions, displaying a more robust performance under tilt and decentration. [J Refract Surg. 2024;40(2):e79-e88.].

Video analysis of optic-haptic-interaction during hydrophobic acrylic intraocular lens implantation using preloaded injectors

OBJECTIVE

To compare the optic-haptic interaction of different hydrophobic acrylic IOLs after using six preloaded injectors.

METHODS

We reviewed the video-recordings of procedures on a total of 388 eyes that underwent phacoemulsification and intraocular lens (IOL) implantation. For six preloaded injectors: multiSert (Hoya Surgical Optics) [System 1], TECNIS Simplicity (Johnson & Johnson Vision) [System 2], TECNIS iTec (Johnson & Johnson Vision) [System 3], AutonoMe (Alcon, Laboratories) [System 4], Bluesert (Carl Zeiss Meditec) [System 5], and Prosert (OphthalmoPro GmbH) [System 6], we noted in each case the time of IOL delivery and made a descriptive observation of IOL insertion and optic-haptic-interaction.

RESULTS

We defined standard haptic behavior where the haptics emerged "folded" from the injector and quickly recovered their pre-implantation appearance. The incidence where the leading haptic emerged in a deformed way for System 1 was 20%, System 2: 19%, System 3: 14%, System 4: 56%, System 5: 24% and System 6: 5%. For trailing haptic deformed behavior, the incidence was 36%, 6%, 4%, 8%, 18% and 2%, respectively for Systems 1 to 6. Optic-haptic adhesion occurred in 2% of cases for System 1, 44% for System 2, 52% for System 3, 48% for System 4, and 11% for System 6 (P < 0.05). Adhesion was not found with System 5.

CONCLUSIONS

We observed different deformed behavior for leading and trailing haptics in the six preloaded systems, some systems had as much as 52% optic-haptic adhesion.

Early Clinical Experience with a New Hydrophobic Acrylic Single-Piece Monofocal Intraocular Lens

Purpose

To evaluate early clinical outcomes and adverse events (AEs) in cataract patients following implantation of a monofocal hydrophobic acrylic IOL with a new optimized non-constant aberration-correcting design (CT LUCIA 621P).

Methods

This retrospective study included patients with visually significant cataracts who underwent implantation of the CT LUCIA 621P IOL. Refraction, corrected (CDVA) and uncorrected (UDVA) visual acuity of the last available visit were used in the analysis. Intraoperative and postoperative AEs of the cohort were reviewed.

Results

A total of 191 eyes of 133 patients with the mean age of 70.2±11.2 years were included in this study. The mean follow-up time of the last available visit was 1.7±1.3 months. The mean postoperative monocular UDVA was 0.09±0.16 logMAR (≈20/25), and 74.9% (143/191) eyes achieved ≥20/25 UDVA. The percentage of eyes with manifest spherical equivalent (MSE) within ±0.50D and ±1.00D of emmetropia was 84.8% (162/191) and 98.4% (188/191), respectively. Linear regression of attempted vs achieved MSE showed a tight relationship, with the coefficient of determination close to 1 (R2=0.99), indicating a very predictable refractive correction. The reported AEs were those typically expected after cataract surgery. There were no AEs related to intraoperative manipulation with the IOL/injector or to postoperative stability of the IOL in the capsular bag. No eye lost ≥2 lines of CDVA.

Conclusion

The implantation of CT LUCIA 621P resulted in good refractive predictability and visual outcomes. No IOL-related adverse events were reported.

Clinical Outcomes of a Monofocal, Optimized, Aspheric, Hydrophobic Acrylic Intraocular Lens Implant

Purpose

To evaluate the refractive and visual outcomes of eyes implanted with monofocal, optimized, aspheric, hydrophobic acrylic intraocular lenses (IOL) following cataract surgery.

Methods

The study assessed 55 eyes implanted with CT LUCIA® 621P IOLs (Carl Zeiss Meditec AG, Jena, Germany) at 3-months postsurgery. The main outcome measures were refractive error, monocular corrected distance visual acuity (CDVA), monocular uncorrected distance visual acuity (UDVA), photopic and mesopic contrast sensitivity, and wavefront aberrations. Patients were asked to complete the Catquest-9SF questionnaire.

Results

At 3 months, the cumulative Snellen visual acuity was 20/20 in 94.55% of eyes and 20/25 or better in 100%. The difference between the UDVA and CDVA was either the same (70.91%) or better (29.09%) in all eyes. The mean Snellen decimal UDVA and DCVA were 1.07 ± 0.15 and 1.13 ± 0.11, respectively. The safety and efficacy indexes were 1.48 and 1.40, respectively. 47.27% of eyes showed a spherical equivalent ±0.13 D, with 92.73% of the eyes were within ±0.50 D and all eyes were within ±1.00 D. The mean spherical equivalent was -0.03 ± 0.30 D and the mean refractive cylinder -0.36 ± 0.34 D. The log photopic and mesopic contrast sensitivity functions were good and similar for all spatial frequencies. All patients reported being either fairly satisfied (score 3) or very satisfied (score 4) with their vision (mean = 3.64 ± 0.49). No intra- and postoperative complications were reported during the 3 months of follow-up.

Conclusion

The current study demonstrates that excellent visual and refractive outcomes, as well as patient satisfaction, can be achieved after cataract surgery with optimized, aspheric CT LUCIA 621P monofocal IOLs.

Clear corneal incision, an important step in modern cataract surgery: a review

A clear corneal incision (CCI) is the most commonly used entrance site in modern phacoemulsification cataract surgery. Despite some initial concerns about increased endophthalmitis rates through a self-sealing CCI, recent literature suggests that the risk of infection with proper wound construction and all other necessary precautions is minimal. The technique of creating a clear corneal incision has, with recent developments in corneal imaging, undergone critical appraisal leading to a better understanding of incision architecture. Many surgeons operate through smaller incisions, and they have a wide choice of surgical instruments to create their corneal incisions. The aim of this review is to discuss the history and the current status of clear corneal incision creation, the design and materials of surgical blades, and the current trends in manufacturing and sustainability. Although disposable instruments have some advantages and are very popular, recycling, if possible, and avoiding unnecessary plastic waste are important considerations. In any case, the step of CCI is a small one for the surgeon, but a big one for the eye. That is why it has to be done with the utmost precision and in-depth knowledge is important.

Evaluation of the mechanical stability of intraocular lenses using digital image correlation

This study aimed to evaluate the mechanical stability of seven different intraocular lens (IOL) haptic designs by using digital image correlation to measure their mechanical biomarkers (axial displacement, tilt, and rotation) under quasi-static compression. The IOLs were compressed between two clamps from 11.00 up to 9.50 mm whilst a 3D deformation dataset was acquired every 0.04 mm. Results revealed that flexible and mixed IOL designs exhibited better mechanical response for smaller compression diameters compared to stiff designs. Conversely, stiff designs performed better for larger compression diameters. These findings may aid in the selection and development of more mechanically stable IOL designs.

Comparison of the Rate of Posterior Capsule Opacification Following Combined Treatment With Topical Dexamethasone 0.1% Plus Ketorolac 0.5% Eye Drops Versus Dexamethasone 0.1% Alone: A Two-Year, Randomized Clinical Investigation

Background and aim The use of non-steroidal anti-inflammatory drugs in animals decreases the incidence of posterior capsular opacification (PCO) following cataract surgery. We evaluated the rate of PCO in patients with cataract surgery and foldable "in the bag" posterior chamber intraocular lens (PC-IOL) implantation treated with combined dexamethasone 0.1% plus ketorolac tromethamine 0.5% versus dexamethasone 0.1% alone. Materials and methods A total of 114 eyes of 101 patients underwent uneventful corneal small-incision phacoemulsification with primary implantation of a foldable acrylic PC-IOL (AcrySof^®, Alcon, Fort Worth, USA). Postoperatively for four weeks, group 1 eyes were treated with dexamethasone 0.1% plus ketorolac tromethamine 0.5% ophthalmic solutions four times daily for each whereas group 2 eyes were treated with dexamethasone 0.1% alone. Other regiments were the same for each group. Patients were evaluated between one- and four-year following surgery. The frequency and timing of severe PCO following surgery that needed Nd:YAG laser posterior capsulotomy were recorded and evaluated. Results The mean (SEM) age of group 1 (n = 54) and group 2 (n = 60) at operation was similar (62.8 ± 2.2 vs. 60.6 ± 1.7 years, respectively). Eighty-eight patients had unilateral cataract and 13 cases had bilateral disease. Overall, the mean follow-up duration was 24.7 months postoperatively (range, 15-48). Clinically significant PCO that finally needed Nd:YAG laser application developed in two eyes (3.7%) in group 1 and in four eyes (6.6%) in group 2, and the difference was not statistically significant (p>0.05). The mean month at capsulotomy was 26.5 in group 1 and 24.3 months in group 2 eyes (p>0.05). Conclusions Topical instillation of ketorolac ophthalmic solution in the immediate period after phacoemulsification and PC-IOL implantation did not seem to influence the incidence of PCO formation two years after cataract surgery.

Micro-Computed Tomography (µCT) as a Tool for High-Resolution 3D Imaging and Analysis of Intraocular Lenses: Feasibility and Proof of the Methodology to Evaluate YAG Pits

INTRODUCTION

Posterior capsule opacification (PCO) is the most frequent late sequelae after successful cataract surgery. Neodymium:yttrium aluminum garnet (Nd:YAG) laser capsulotomy is considered the gold standard and a well-accepted, safe, and effective measure in treating PCO. However, iatrogenic damage of the intraocular lens (IOL) due to inappropriate focusing is a quite common side effect. These permanent defects (YAG pits) can critically affect overall optical quality.

METHODS

In this laboratory study, we used the micro-computed tomography (µCT) technique to obtain high-resolution 3D images of the lens and the YAG pits.

RESULTS

To the best of our knowledge, this is the first description of a detailed analysis of IOLs with µCT technology. This non-destructive technique seems to be ideal for comparative studies, measuring dimensions of the damage, and visualizing shooting channels within the material.

CONCLUSION

µCT is excellently suited to examine an IOL in detail, analyze optics and haptics in three dimensions, and to describe all kinds of changes within the IOL without damaging it.

Effects of intraocular lens anterior edge design on anterior capsule morphology changes following femtosecond laser-assisted capsulotomy

PURPOSE

To compare morphological changes in the anterior capsule of two intraocular lenses (IOLs) with different anterior edge designs 6 months after femtosecond laser-assisted capsulotomy surgery (FLACs).

METHODS

This study included 168 eyes from168 patients undergoing FLACs. Group A included 74 eyes from 74 patients who had an Acrysof IQ Restor SN6AD3 IOL implantation with a flat anterior edge and Group B included 94 eyes of 94 patients with a TECNIS Multifocal ZMB00 IOL implantation and a "peak-like" anterior edge. All patients were followed up for 6 months. We assessed anterior capsule morphological changes including variation of anterior opening diameters and lens epithelial cell (LEC) proliferation in four directions, variation of anterior opening area, and the level of anterior capsule opacification (ACO).

RESULTS

Variation of anterior opening diameters in 4 directions were significantly lower in Group B (P < 0.05). Obvious shrinkage ratio of anterior opening diameters and contraction of anterior opening area (P < 0.05) appeared in Group A. LEC proliferation was along the "peak" in Group B, while it spread to the edge of anterior capsule in Group A. ACO grades 6 months after operation in Groups A and B were as follows: grade I in 28.38% and 82.98% of eyes, grade II in 51.35% and 17.02% of eyes, and grade III in 20.27% and 0% of eyes, respectively.

CONCLUSIONS

These findings suggest that a "peak-like" IOL anterior edge design played an important role in maintaining the morphology of anterior capsule in the early postoperative stage.

Evaluating impact of Nd: YAG laser associated defects on optical quality of hydrophilic and hydrophobic intraocular lenses using visualization of light propagation and USAF test targets

BACKGROUND

Neodymium:yttrium aluminum garnet (Nd:YAG) laser capsulotomy is a well-accepted, safe, and effective measure in the treatment of posterior capsule opacification. However, iatrogenic intraocular lens damage is a relatively common side effect that happens due to inappropriate focusing during the procedure. This experimental study analyzes the impact of YAG-pits to obtain qualitative information.

METHODS

Acrylic, monofocal hydrophilic and hydrophobic intraocular lenses (IOLs) with 6.0 mm optic and the with the same power (21D) were studied. First, all measurements were done with unmodified IOLs. Damage was intentionally created, performing YAG-pits (n = 5) in the central area of the lens optic (3.0 mm) using a photodisruption laser with the same energy level of 1.8 mJ. To simulate the cruciate pattern, the 5 defects were created in a cross shape within the 3.0 mm optical zone. Afterwards, all laboratory measurements were repeated: These included the United States Air Force (USAF) resolution test chart to study the imaging performance of the IOL, light field measurements to show the course of the rays behind the IOL and the modulation transfer function (MTF) measurements were analyzed.

RESULTS

Evaluating USAF showed that unmodified lenses produced a sharper image. Damaged lenses led to a more blurred image and to the impression of a lower contrast with a kind of halo/glare effect. The light field measurement showed that YAG-pits led to a kind of dispersion and scattering effect, which was higher in hydrophobic IOLs. MTF showed a deterioration in damaged hydrophilic and hydrophobic IOLs, respectively.

CONCLUSION

Our experimental study confirms that YAG-pits can reduce imaging quality of intraocular lenses. These defects behave as a new Huygens source, distribute a spherical wave that additionally illuminate the background of the USAF target. It can be assumed that material properties of the IOL (water content, refractive index) play an important role and affect results. The impact level is strongly dependent on the number, size and position of YAG-pits within the optic.

LIMITATION

Only monofocal IOLs have been investigated so far, further tests with various IOL optics have to follow. In addition, simulating the circular pattern of YAG capsulotomy is necessary.

Effects and Prognosis of Cataract Surgery in Patients with Retinitis Pigmentosa

INTRODUCTION

Cataract extraction could improve visual acuity (VA) for patients with retinitis pigmentosa (RP), while the surgery may increase photoreceptor degeneration through light damage. In this study, we conducted a systematic review and meta-analysis to investigate the effectiveness and prediction of VA after cataract surgery in patients with RP.

METHODS

We comprehensively extracted data from literature of available studies with quality control processing. Improvement of VA before and after cataract surgery of different durations of follow-up and different structural integrity of the preoperative macular ellipsoid zone (EZ) in patients with RP were compared. VA was measured by the logarithm of the minimum angle of resolution (logMAR).

RESULTS

Sixteen studies were subjected to analysis. Postoperative VA was significantly improved versus preoperative, with a mean difference (MD) of 0.57 [95% confidence interval (CI) 0.45, 0.69], and a fixed-effect model was applied during follow-up durations of 1 day to 1 month (I² = 0%). Similarly, for follow-up durations of 1-3 months, 3-6 months, and 6-12 months, postoperative VAs were all better than preoperative values, with MDs of 0.36 (95% CI 0.31, 0.41), 0.35 (95% CI 0.23, 0.46), and 0.22 (95% CI 0.14, 0.30) (I² < 50%). For follow-up duration of 1-5 years, the random-effect model was applied for higher heterogeneity (I² = 81%), with an MD of 0.26 (95% CI 0.09, 0.43). There was no significant difference in the improvement of the EZ-invisible group, with an MD of 0.27 (95% CI - 0.17, 0.70) (I² = 82%). There were significant differences between EZ-abnormal and EZ-normal groups in preoperative and postoperative VA, with MDs of 0.56 (95% CI 0.27, 0.85) and 0.46 (95% CI 0.27, 0.65) (I² > 50%).

CONCLUSIONS

Cataract surgery could improve VA for patients with RP during long-term follow-up, and the surgery is not recommended for patients with invisible preoperative macular EZ. However, further studies are required to address the problem of excessive light exposure to the degenerated retina in patients with RP with the cataract removed. The study protocol was registered on the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42022340165).

Refractive and Visual Outcomes of a Monofocal Non-Constant Aberration Aspheric Intraocular Lens

Purpose

To evaluate the refractive and visual outcomes following cataract surgery and implantation of a new monofocal non-constant aberration aspheric intraocular lens (IOL).

Methods

Ninety eyes of 86 patients who underwent implantation the CT LUCIA 621P IOL (Carl Zeiss Meditec AG) were retrospectively analyzed in this study. Main outcome measures were refractive error and monocular corrected distance visual acuity (CDVA) and monocular uncorrected distance visual acuity (UDVA) values. Patients were evaluated at 1-month post-surgery and intra- and post-operative complications were recorded.

Results

Eighty percent of the eyes showed a CDVA of 20/25 or better before surgery. The postoperative mean values of monocular distance Snellen decimal UDVA and CDVA were 0.64±0.22 and 0.89±0.13, respectively. All eyes showed the same or better difference between UDVA and CDVA. In relation to the postoperative spherical equivalent, the highest percentage of eyes, 31.11%, was for the range between −0.50 and −0.14D followed by 22.22% for the ±0.13D range. Ninety percent of the eyes were within ±1.00 D and 73.33% of eyes within ±0.50 D. The mean postoperative spherical equivalent was −0.18±0.55D. 37.78% and 76.67% of the eyes showed a value ≤0.50 D and ≤1.00D, respectively, being the mean postoperative refractive cylinder −0.81±0.50D. No adverse events were reported in whole sample intra and postoperatively.

Conclusion

The present study shows that cataract surgery with an monofocal non-constant aberration aspheric IOL implantation resulted in good visual performance and refractive outcomes. This lens may be considered as a valid choice for patients in a standard-routine cataract surgery practice.