[Opacification of intraocular lenses: laboratory and clinical findings]

[Secondary intraocular lens implantation]

In recent years, techniques for the secondary implantation of intraocular lenses have undergone significant further development. Despite the wide range of surgical indications, IOL dislocation and aphakia following complicated cataract surgery or other complicated intraocular procedures and trauma remain the most common reasons for secondary IOL implantation. In cases where it is not feasible to place the artificial lens in the capsular bag due to zonular weakness or insufficient stability of the capsular bag, the intraocular lens can be implanted in the anterior chamber or fixed in the ciliary sulcus, on the iris or on the sclera. The techniques differ not only in the anatomical structure of the fixation, but also in the type of intraocular lens and materials used. While some methods are technically easier and quicker to perform, the learning curve for other techniques is flatter and takes more time. The experienced ophthalmic surgeon should be familiar with several of these methods and be aware of the advantages, disadvantages and contraindications of the individual techniques in order to be able to choose the most suitable method based on the findings of the individual patient.

Functional Outcomes After Refractive Lens Exchange With Implantation of a Glistening-Free Diffractive Trifocal Intraocular Lens

PURPOSE

To evaluate visual outcomes and patient-reported results after bilateral femtosecond-laser-assisted refractive lens exchange (RLE) with the implantation of a diffractive trifocal intraocular lens.

DESIGN

Prospective interventional case series.

METHODS

A study of 27 patients (54 eyes) implanted with the Clareon PanOptix (Alcon) multifocal intraocular lens during femtosecond-laser-assisted RLE in a university hospital setting. The uncorrected (UDVA) and corrected (CDVA) distance visual acuity, uncorrected (UIVA) and distance-corrected (DCIVA) intermediate visual acuity at 60 cm, uncorrected (UNVA) and distance-corrected (DCNVA) near visual acuity at 40 and 33 cm were evaluated at 3 months postoperatively and compared with the preoperative values. In addition, we assessed the postoperative defocus curve, mesopic and photopic contrast sensitivity, and patient-reported spectacle independence.

RESULTS

The mean postoperative binocular UDVA was -0.02 ± 0.06 logMAR and CDVA was -0.11 ± 0.05 logMAR. The UIVA was -0.07 ± 0.05 logMAR and DCIVA was -0.07 ± 0.07 logMAR. The UNVA at 40 cm was 0.03 ± 0.09 logMAR and DCNVA was -0.02 ± 0.06 logMAR; and, at 33 cm UNVA was 0.14 ± 0.10 logMAR and DCNVA was 0.11 ± 0.08 logMAR. In comparison to the preoperative binocular CDVA (-0.12 ± 0.08 logMAR), no statistically significant change was observed (P = 1.0), while all the other binocular visual acuities improved (P < .01). In the mean binocular defocus curve, the visual acuity was better than 0.10 logMAR in the range between +0.5 D and -3.0 D. The mean contrast sensitivity was within the normal range, and most patients reported complete spectacle independence.

CONCLUSIONS

The RLE surgery improved uncorrected visual acuity at far, intermediate, and near distances without negatively affecting the CDVA. Patients achieved a high level of spectacle independence.

[Correction of aphakia in cases of insufficient capsular bag stability]

A variety of situations can lead to the need for an alternative method of intraocular lens (IOL) fixation if implantation in the capsular bag is not possible. Depending on the situation, sulcus-fixated IOLs, iris-fixated IOLs (IFIOLs) and scleral-fixated IOLs (SFIOLs) are available. With SFIOLs, a distinction is made between suture-fixated and sutureless-fixated techniques. This paper summarizes the advantages and disadvantages of the different approaches, including the newer methods of sutureless SFIOLs. The decision on a specific approach in the individual case depends on both the individual circumstances of the patient and the experience of the surgeon.

Impact of Calcium and Phosphorus Levels on Optical Deterioration in Primary and Secondary Intraocular Lens Calcification

Purpose

The purpose of this study was to investigate the impact of calcium and phosphorus levels on optical deterioration in primary and secondary intraocular lens (IOL) calcification.

Methods

A total of 18 explanted IOLs, 10 with primary, and 8 with secondary calcification, were examined. Straylight and light loss were evaluated as predictors of optical impairment. The individual amount of calcium and phosphorus was determined using thermogravimetry followed by emission spectroscopy (ICP-OES). The relationship between calcification and optical impairment was investigated.

Results

Primary calcified IOLs contained significantly higher amounts of calcium and phosphorus compared to secondary calcified IOLs (calcium P < 0.02 and phosphorus P < 0.01), translating to greater light loss and significantly higher straylight mean values. In secondary calcification, light loss and straylight were highly dependent on calcium (r² = 0.90, P < 0.001 and r² = 0.70, P < 0.01) and phosphorus (r² = 0.66 and r² = 0.65, both P < 0.02), whereas these correlations were much lower in primary calcification (all r = 0.25, P > 0.05).

Conclusions

ICP-OES is the first methodology to precisely assess the calcium and phosphorus content in IOL calcification thus based on mass ratios allowing improved molecular characterization. Primary calcification showed higher amounts of calcium and phosphorus, translating to higher straylight and light loss and thus a higher risk for impairment of visual quality than secondary calcification.

Translational Relevance

This study is the first to quantify calcification and demonstrate the relationship to optical deterioration in IOLs, substantially contributing to understand how visual impairment arises in patients with calcified IOLs.

Higher phosphate concentrations as in aqueous humor of diabetic patients increase intraocular lens calcification

BACKGROUND

Clinical evidence suggests an association between phosphate concentrations in aqueous humor and the risk of intraocular lens (IOL) calcification. To test this hypothesis the influence of different phosphate concentrations on IOL calcification was evaluated in an in vitro electrophoresis model.

METHODS

20 IOLs of two hydrophilic IOL models (CT Spheris 204, Zeiss; Lentis L-313, Oculentis) and one hydrophobic control IOL model (Clareon CNA0T0, Alcon) were exposed to physiologic and elevated phosphate concentrations, similar to diabetic aqueous humor. IOL calcification was analyzed by alizarin red staining, von Kossa staining, scanning electron microscopy, energy dispersive x-ray spectroscopy and transmission electron microscopy with electron diffraction.

RESULTS

Higher phosphate concentrations were associated with IOL calcification. Analyses of IOL surfaces and cross-sections documented calcification in no CT Spheris and 4 Lentis IOLs following exposure to 10 mM Na2HPO4, compared with 7 and 11 positive analyses following exposure to 14 mM Na2HPO4, respectively. Furthermore, a clear association between IOL calcification and the duration of electrophoresis was demonstrated, confirming increased phosphate concentrations and duration of exposure as risk factors of IOL calcification.

CONCLUSIONS

Findings suggest that higher phosphate concentrations in aqueous humor, as seen in diabetic patients, contribute to an increased IOL calcification risk, potentially explaining clinical observations showing an increased risk of IOL calcification in patients with diabetes.

In vivo comparison of implantation behavior and laboratory analysis of two preloaded intraocular lens injectors

PURPOSE

We evaluated implantation behavior and injector damage of two different IOL injector systems, the Multisert and the AutonoMe.

DESIGN

Prospective, randomized, comparative study with laboratory investigation.

METHODS

We examined used injectors from 48 bilateral cataract cases and assessed video recordings of each Implantation. All eyes were intraindividually randomized for treatment with one of the two IOL injectors. Implantation videos were reviewed for inadvertent events and the time for different implantation steps was determined. The injector nozzle tips were examined using light and scanning electron microscopy (SEM). Damage was graded using the Heidelberg Score for IOL injector damage (HeiScore). Three months postoperatively, IOLs were assessed for material changes.

RESULTS

Implantation was without critical events in 96 of 96 eyes. Mean implantation time was 41.90 ± 7.11 s with the Multisert and 52.22 ± 12.06 s with the AutonoMe. In the AutonoMe group, we observed 4 eyes (8.3%) with a failed docking attempt, 28 eyes (58.3%) with a haptic adherence, one case (2.1%) of straight leading haptic and 2 cases (4.2%) of intrawound IOL manipulation. There were no events observed in the Multisert group. The mean HeiScore values were 0.87 ± 0.61 and 3.68 ± 0.47 for the AutonoMe and Multisert. 3 months postoperatively, IOL material changes were absent.

CONCLUSIONS

Both injectors allowed safe and controlled implantation. Using Multisert, implantation behavior was more consistent. The injectors showed different damage profiles with a higher damage score for the Multisert.The study is registered at the German Clinical Trials Register (Deutsches Register Klinischer Studien; reference number: DRKS00007837).

[Hydrophobic surface properties of hydrophilic acrylic lenses do not protect against calcification]

BACKGROUND

Opacification through calcification of hydrophilic acrylic intraocular lenses is a serious complication of cataract surgery, which usually results in explantation of the lens. In the process of calcification, the intraocular lens material plays a crucial role: calcification only occurs in hydrophilic acrylic lenses. Hydrophobic acrylic lenses show no crystal formation within the polymer. Hydrophilic acrylic lenses from some manufacturers have hydrophobic surface properties. The question arises as to what influence these surface properties have on the risk of calcification.

OBJECTIVE

The present study investigated whether the hydrophobic surface properties of hydrophilic acrylic lenses can prevent calcification.

MATERIAL AND METHODS

Using an electrophoretic in vitro model of calcification, two hydrophilic lenses with hydrophobic surface properties were compared to two hydrophilic lenses and a hydrophobic negative control to determine the risk of calcification. The lenses were then analyzed by optical microscopy, Alizarin Red and Von Kossa staining, scanning electron microscopy (SEM) and energy dispersive X‑ray spectroscopy (EDX).

RESULTS

All four hydrophilic lens models showed calcification within the polymer. No difference was found between the hydrophilic lenses and the hydrophilic lenses with hydrophobic surface properties in terms of crystal formation. The hydrophobic negative control showed no calcification.

CONCLUSION

The investigation conducted in this study under standardized conditions could show that hydrophobic surface properties of hydrophilic acrylic lenses do not protect against calcium phosphate crystal formation within the polymer. There also is a risk of calcification in these lens models.

Aetiology and Management of IOL Dislocations

Early (< 3 months) intraocular lens (IOL) dislocation occurs due to insufficient fixation in the capsular bag, while late dislocation (≥ 3 months) is due to increasing insufficiency of the zonular apparatus. Iris-fixated IOL (IFIOL) and suture- or sutureless-fixated scleral IOL (SFIOL) are currently the most commonly used methods when IOL exchange is indicated. Different methods of scleral fixation with or without sutures have been described. The most important techniques are summarised in this paper. IFIOL and SFIOL allow comparable visual outcomes but differ in their risk profile. The decision of which method to use should be made case by case and in accordance with the surgeon's preference.

Opacification of Hydrophilic Acrylic Intraocular Lenses: Overview of Laboratory Methods for Histological Analysis and Replication of IOL Calcification

Opacification of intraocular lenses (IOLs) due to material changes is a serious complication that can compromise the good visual outcomes of uncomplicated cataract surgery. In hydrophobic acrylic IOLs, opacification can result from glistening formation, while in hydrophilic acrylic IOLs, there is a risk of calcification due to the formation of calcium phosphates within the polymer. Over time, various methods have been developed to investigate calcification in hydrophilic acrylic IOLs. The aim of this article is to provide an overview of standard histological staining and models used to simulate IOL calcification. Histological staining can be used to detect calcification and assess the extent of crystal formation. The development of in vivo and in vitro replication models has helped to identify the underlying pathomechanisms of calcification. In vivo models are suitable for assessing the biocompatibility of IOL materials. Bioreactors as an in vitro model can be used to investigate the kinetics of crystal formation within the polymer. The replication of IOL calcification under standardized conditions using electrophoresis allows for the comparison of different lens materials with respect to the risk of calcification. The combination of different analytical and replication methods can be used in the future to further investigate the pathomechanisms of calcium phosphate crystal formation and the influence of risk factors. This may help to prevent calcification of hydrophilic acrylic IOLs and associated explantation and complications.

Differential Diagnosis of Changes in Intraocular Lenses

Differentiating between various intraocular lens (IOL) changes can be a challenge. In particular, certain IOL models carry the risk of late postoperative calcification. A major cause of IOL exchange surgery could be avoided if appropriate modifications were made during the IOL manufacturing process. The use of a hydrophilic acrylate carries the risk of IOL calcification, especially when a secondary procedure, such as a pars plana vitrectomy or other procedures using gas or air, is performed. In secondary IOL calcification, there is a wide range of opacification patterns, which are usually located in the centre on the anterior surface of the IOL or sometimes elsewhere. Often, granular deposits accumulate just below or on the surface of the IOL, leading to significant deterioration in visual quality and eventually requiring IOL exchange surgery. Therefore, in the case of eyes requiring secondary surgical intraocular intervention in the future, the use of hydrophilic IOLs should be critically evaluated. With regard to hydrophobic IOL materials, there are clear differences in the susceptibility to the formation of glistenings. Over time, there has been a significant decrease in glistening formation over the past 30 years due to optimisation of the material. With hydrophobic IOLs, special care should also be taken to avoid mechanical damage. In general, the only treatment option for functionally-impairing IOL opacification is surgical lens exchange, which carries potential risks of complications. In cases with a low degree of functional impairment, and especially in eyes with additional ocular diseases, it may be difficult to weigh the risk of additional surgery against the potential benefit. In some cases, it may be more appropriate not to perform an IOL exchange despite the IOL opacification. Recent visualisation methods that allow high-resolution analysis of the opacities in vivo and in vitro may be used in the future to estimate the functional effects of various IOL material changes on the optical quality.

Flexural and Cell Adhesion Characteristic of Phakic Implantable Lenses

Background and Objectives: In this study, we aimed to compare the physical properties of hole-implantable collamer lenses (H-ICLs) and implantable phakic contact lenses (IPCLs) and investigate their flexural and cell adhesion characteristics. Materials and Methods: Transverse compression load to achieve lens flexion and static Young's modulus were measured in H-ICLs and IPCLs using designated equipment. Load was measured both with and without restraining the optic section of the lenses. Adhesion of iHLEC-NY2 cells to the lens surfaces was examined using phase-contrast microscopy, and cell proliferation activity was evaluated using WST-8 assay. Results: The H-ICL showed a greater tendency for transverse compression load compared to IPCL, while the IPCL showed a higher Young's modulus with respect to the force exerted on the center of the anterior surface of the optic section. The joint between the optic section and haptic support in the IPCL was found to mitigate the effects of transverse compression load. Both lens types showed minimal cell adhesion. Conclusions: Our findings indicate that H-ICLs and IPCLs exhibit distinct physical properties and adhesive characteristics. The IPCL demonstrated higher Young's modulus and unique structural features, while the H-ICL required greater transverse compression load to achieve the flexion required to tuck the haptic supports into place behind the iris to fix the lens. The observed cell non-adhesive properties for both lens types are promising in terms of reducing complications related to cell adhesion. However, further investigation and long-term observation of IPCL are warranted to assess its stability and potential impact on the iris. These findings contribute to a better understanding of the performance and potential applications of H-ICLs and IPCLs in ophthalmology.

Imaging Function and Relative Light Transmission of Explanted Opacified Hydrophilic Acrylic Intraocular Lenses

We evaluated the influence of intraocular lens (IOL) opacification on the optical performance of explanted hydrophilic acrylic IOLs. We performed a laboratory analysis of 32 Lentis LS-502-1 (Oculentis GmbH, Berlin, Germany) IOLs, explanted due to opacification, in comparison with six clear unused samples of the same IOL model. Using an optical bench setup, we obtained modulation transfer function (MTF), Strehl ratio, two-dimensional MTF, and United States Air Force (USAF) chart images. In addition, we assessed light transmission through the IOLs. The MTF values of opacified IOLs at 3-mm aperture were similar to those of clear lenses, with the median (interquartile range) values of 0.74 (0.01) vs. 0.76 (0.03) at the spatial frequency of 50 line pairs per millimeter in clear and opacified IOLs, respectively. The Strehl ratio of opacified lenses was not lower than that of clear lenses. The USAF-chart analysis showed a considerable reduction in brightness in opacified IOLs. The median (interquartile range) relative light transmission of opacified IOLs in comparison to clear lenses was 55.6% (20.8%) at the aperture size of 3 mm. In conclusion, the explanted opacified IOLs had comparable MTF values to those of clear lenses but significantly reduced light transmission.

Development of a standardized in vitro model to reproduce hydrophilic acrylic intraocular lens calcification

Opacification through calcification of hydrophilic acrylic intraocular lenses (IOL) is a severe complication after cataract surgery. Causing symptoms that range from glare through to severe vision loss, the only effective therapy is explantation of the opacified IOL so far. Although IOL calcification is a well-described phenomenon, its pathogenesis is not fully understood yet. The purpose of the current study was to develop a laboratory model to replicate IOL calcification. Calcification could be reproduced using a horizontal electrophoresis and aqueous solutions of calcium chloride and disodium hydrogen phosphate. The analysis of the in vitro calcified IOLs was performed using light microscopy, Alizarin Red and Von Kossa staining, scanning electron microscopy, energy dispersive x-ray spectroscopy and electron crystallography using transmission electron microscopy and electron diffraction. The presented laboratory model could be used to identify hydrophilic IOLs that are at risk to develop calcification and to assess the influence of associated risk factors. In addition, it can serve as a research tool to further understand this pathology.

Comparative analysis of in vitro accelerated glistening formation in foldable hydrophobic intraocular lenses

PURPOSE

To analyse and compare the propensity to form glistenings in 4 different types of hydrophobic acrylic intraocular lenses (IOLs): Alcon AcrySof ® MA60AC, HOYA iSert® PC-60AD, Bausch&Lomb enVista, and Kowa Avansee™ PU6A.

METHODS

We used an accelerated laboratory method to create glistenings. IOLs were first immersed in saline at 45 °C for 24 h and then at 37 °C for 2.5 h. Microvacuole (MV) density and size were documented and calculated using an image analysis program.

RESULTS

Median density of glistenings [MV/mm2] for Alcon AcrySof ® MA60AC was 623 (range 507-804), for HOYA iSert® PC-60AD 1358 (range 684-2699), for Bausch&Lomb enVista 2 (range 1-2), and for Kowa Avansee™ PU6A 1 (range 1-4). The prevailing MV size was: 0-5 µm for Hoya IOLs, 5-10 µm for Alcon IOLs, 20-50 µm for Bausch&Lomb IOLs, and 5-50 µm for Kowa IOLs.

CONCLUSIONS

Glistenings could be induced in all studied IOLs using the accelerated laboratory method. The Alcon AcrySof ® MA60AC and HOYA iSert® PC-60AD IOLs showed MV of high density, while the glistenings in the Hoya IOLs were smaller in size compared to the Alcon IOLs. The MV density was minimal in the Bausch&Lomb enVista and Kowa Avansee™ PU6A IOLs. The propensity of the Alcon AcrySof ® MA60AC IOLs to form glistenings in vitro correlated with the findings of clinical results that are already published.

Visualization of Forward Light Scatter in Opacified Intraocular Lenses and Straylight Assessment

Background: Qualitative visualization of forward light scatter and quantitative straylight measurement of intraocular lenses (IOLs). Methods: We analyzed two calcified IOL-explants, the Euromaxx ALI313Y (Argonoptics GmbH) and the LS-312 MF30 (Oculentis BV), one IOL with artificially induced glistenings (PC-60AD, Hoya), and one control (CT Asphina 409MP, Carl Zeiss Meditec AG) free of any opacification. Analysis included light microscopy, qualitative light scatter visualization using ray propagation imaging technique, and quantitative straylight measurement using C-Quant (Oculus). Results: More light scattering effect—visible as increased light intensity outside the IOL’s main focus—was evident in all opacified IOLs than the control. The highest straylight levels were observed in the Euromaxx (289.71 deg²/sr), which showed extensive granular deposits throughout its optic, followed by the MF30 (78.58 deg²/sr), which only showed opacification in its center. The glistenings-IOL demonstrated numerous microvacuoles within the optic and had straylight levels of 22.6 deg²/sr, while the control showed the lowest straylight levels (1.7 deg²/sr). Conclusions: Ray propagation imaging technique allowed qualitative assessment of off-axis veils of light that result from increased forward light scattering. Straylight was increased in all opacified lenses compared to the clear control lens. The IOL opacifications are significant sources of glare.

Intraocular Bag-in-the-Lens Exchange: Indications, Outcomes and Complications

PURPOSE

To report the indications, outcomes, and complications regarding the Bag-in-the-lens (BIL) intraocular lens (IOL) exchanges over a period of 13 years in a tertiary ophthalmologic centre.

SETTING

Department of Ophthalmology of the University Hospital of Antwerp (UZA).

DESIGN

Observational retrospective study.

PATIENTS AND METHODS

Between 2003 and 2020, 12 176 patients were operated using the BIL technique. We included adult patients who underwent an intraocular BIL exchange and recorded the demographics, indications, outcomes, and complications.

RESULTS

Fifty-nine eyes of 59 patients who underwent a BIL exchange between 2007 and 2020 were included (0.48%). The mean age was 61.15 ±13.53 years. The mean time between primary surgery and IOL exchange was 25.73 ± 41.88 months. The main indication for explantation was refractive surprise mostly related to the patients' risk factors e.g. preoperative corneal and refractive surgery. The mean preoperative uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were 0.36 ± 0.24 and 0.79 ± 0.24 respectively. The postoperative 1 month-UDVA and CDVA were 0.66 ± 0.28 and 0.86 ± 0.19 respectively. The improvement in UDVA was statistically significant (<0.0001). The most common peroperative complication was damage to the anterior hyaloid in 9 eyes (15%), which did not prohibit reimplantation of a secondary BIL.

CONCLUSIONS

BIL to BIL exchange is an viable and successful technique that provides good refractive results with few, manageable complications. Because of the tertiary profile of our centre with referral of complex cases, BIL was our preferred IOL in patients at risk of postoperative refractive surprise.

A Novel Approach for Assessing Visual Impairment Caused by Intraocular Lens Opacification: High-Resolution Optical Coherence Tomography

PURPOSE

To quantify in vitro straylight induced by intraocular lens (IOL) localized opacification using an anterior segment optical coherence tomography (OCT) device.

DESIGN

Laboratory investigation.

METHODS

We obtained high-resolution OCT cross-section images of 44 explanted IOLs using a new in vitro application for an anterior segment OCT device, the Anterion (Heidelberg Engineering, Heidelberg, Germany). In 24 cases, the reason for IOL explantation was a centrally localized opacification, the sequela of a secondary ocular surgery. As a control, we used 20 IOLs removed after an IOL (sub-)luxation. Using image analysis, we found a threshold area value representing a metric for the amount of opacification in a region of interest in the IOL's central optic. We used a modified C-Quant straylight meter (Oculus, Wetzlar, Germany) to quantify light scattering. We derived a linear regression from calculating the correlation between the amount of opacification and straylight.

RESULTS

We visualized different amounts of IOL opacification using the OCT device. The opacified lenses showed a mean threshold area of 6.7% ± 3.3% and mean straylight was 95.1 ± 75.6 deg²/sr. The clear group's mean threshold area was 2.0% ± 0.8% and 5.0 ± 3.4 deg²/sr mean straylight. Straylight correlated statistically significantly with the threshold area, with a correlation coefficient of R² = 0.80, P < .001.

CONCLUSIONS

This high-resolution OCT imaging technique can be used to visualize IOL opacities. The amount of opacification correlated well with the straylight induced by the lens. Anterior segment OCT imaging might be used in the future as a tool for predicting the extent of visual impairment and aid clinicians to quantify patients' complaints.

Quantitative evaluation of microvacuole formation in five intraocular lens models made of different hydrophobic materials

In this laboratory study, we assessed the resistance to microvacuole (glistening) formation in hydrophobic intraocular lenses (IOLs). Glistenings were induced in five lenses each of five different hydrophobic acrylic IOL models, using an established in vitro laboratory model: 800C (Rayner, Worthing, UK), AcrySof SN60WF (Alcon, Fort Worth, USA), Tecnis ZCB00 (Johnson & Johnson Vision, Santa Ana, USA), Vivinex XY1 (Hoya, Tokyo, Japan) and CT Lucia 611P (Zeiss, Oberkochen, Germany). We evaluated the number of microvacuoles per square millimeter (MV/mm2) in the central part of each IOL. Results were analyzed statistically, and mean glistening numbers were ranked, with the highest in the SN60WF which had 66.0 (±45.5) MVs/mm, followed by the 611P with 30.7 (±8.4) MVs/mm2. The 800C and XY1 showed comparable values of 2.0 (±3.6) and 2.7 (±2.4) MVs/mm2, respectively. ZCB00 had the lowest number with 0.9 (±0.6) MVs/mm2. This study shows that the resistance to glistening formation differs depending on the hydrophobic acrylic copolymer composition of the IOL material. Some IOLs from current clinical use are still prone to develop glistenings whereas others, including the ZCB00, 800C and XY1 show high resistance to microvacuole formation.

[Opacification of Intraocular Lenses]

The spectrum of complications in the use of intraocular lenses (IOL) is different today from at the time of their introduction. Opacities in the IOL material are increasingly described in the literature as a reason for IOL explantation. This paper provides an overview of the different forms of IOL material opacities. Currently relevant forms of IOL material opacities and their effects on optical quality are summarized. The main reason for opacification in hydrophilic IOLs is calcification, whereas in hydrophobic IOLs it is mainly the formation of so-called glistenings that is reported. Most material opacities affect various optical parameters and lead to increased intraocular straylight. In case of a disturbing material opacification, the only therapeutic option is to replace the opacified IOL.

Eintrübung von Intraokularlinsen

Das Spektrum an Komplikationen und die Explantationsgründe bei der Verwendung von Intraokularlinsen (IOL) haben sich durch die Weiterentwicklung der Kataraktchirurgie verändert. Eintrübungen des Materials beeinflussen dabei unterschiedlich stark die optische Qualität. Im Fall einer störenden Eintrübung des Materials ist auch heute noch – trotz aller Fortschritte auf dem Gebiet der IOL-Materialien – ein Austausch der IOL die einzige Behandlungsoption.

In-vitro glistening formation in six different foldable hydrophobic intraocular lenses

Background

Glistenings describe small, refractile microvacuoles that may arise within the intraocular lens (IOL) material and reduce the patients’ quality of vision. Lenses composed of hydrophobic acrylic material are particularly affected by glistening formation. In this study, we compared the tendency of glistening formation in six different types of hydrophobic acrylic intraocular lenses (IOLs).

Methods

We used a well-established accelerated laboratory method to develop glistenings in the following IOLs: Vivinex XY1 (Hoya), AcrySof SN60WF (Alcon), Tecnis ZCB00 (AMO), Avansee PN6A (Kowa), Aktis SP NS-60YG (Nidek), and CT Lucia 601P (Zeiss). IOLs were first immersed in saline at 45 °C for 24 h and then at 37 °C for 2.5 h in a water bath. Microvacuole (MV) density and size (Miyata grading) were documented and calculated using an image analysis program.

Results

The mean glistening density [MV/mm²] and mean Miyata grading (in brackets) were: Vivinex: 11.6 ± 5.7 (0), SN60WF: 264.4 ± 110.3 (2.6), Tecnis: 6.0 ± 2.8 (0), Avansee: 2.2 ± 0.7 (0), Aktis: 851.4 ± 59.4 (3+) and CT Lucia: 71.0 ± 71.6 (1).

Conclusions

While all tested IOLs showed glistenings with the accelerated laboratory method, the Aktis and SN60WF showed the highest microvacuole density, followed by the CT Lucia. In comparison, the Vivinex, Tecnis, and Avansee IOLs showed far fewer number of glistenings.