Material Analysis and Optical Quality Assessment of Opacified Hydrophilic Acrylic Intraocular Lenses After Pars Plana Vitrectomy

Quantification of Straylight Induced by Silicone Oil Adherent to Intraocular Lenses of Different Materials

PURPOSE

A complication of using silicone oil as an intraocular endotamponade is its adhesion to intraocular lenses (IOLs). Forward light scattering is a measure to quantify the optical disturbance caused by adherent oil droplets. We tested the straylight caused by silicone oil adhesion to different IOLs and examined whether an approved cleaning solution, F4H5, reverses the induced straylight.

DESIGN

An experimental study.

METHODS

Two hydrophobic acrylic IOL models and 1 hydrophilic model with a hydrophobic surface (n = 8 per model: 24 lenses) had straylight measured before contact with silicone oils, providing a baseline for subsequent testing: 12 lenses with lighter-than-water silicone oil (Siluron 2000) and 12 with heavier-than-water oil (Densiron 68). The final measurement was performed after cleansing with F4H5 when we used scanning electron and light microscopy to detect surface changes.

RESULTS

Straylight was majorly increased in IOLs with adherent silicone oil (baseline vs adherent oil median 3.1 [2.1, 3.9] and 39.7 [22.7, 87.8] deg2/sr, respectively; P < .001). No difference was seen between heavier- and lighter-than-water silicone oils. Between IOL types, induced straylight varied significantly, with 1 hydrophobic model reaching the highest average straylight. F4H5 significantly reduced straylight values in all IOL types (median 9.4 [5.4, 13.8] deg2/sr). The microscopy revealed surface changes on the IOLs even after cleaning.

CONCLUSIONS

Silicone oil adhesion to IOLs can induce amounts of straylight known to cause severe optical disturbance. F4H5 cleansing solution reversed straylight values to only slightly increased values. We found no difference in straylight formation between the lighter- and heavier-than-water silicone oils.

FIL SSF intraocular lens opacification after gas tamponade: A case series

PURPOSE

To report three cases of postoperative opacification of sutureless scleral-fixed hydrophilic intraocular lens (FIL SSF IOL, Soleko, Italy) after gas tamponade. Two cases occurred after pars plana vitrectomy and one case after Descemet membrane endothelial keratoplasty.

CASE REPORT

Two diabetic patients underwent a FIL SSF IOL implantation after posterior capsular rupture during cataract surgery. Rhegmatogenous retinal detachment (RRD) was observed in one patient during the initial surgery. A second patient developed a RRD five months after surgery. Both RRDs were treated with pars plana vitrectomy and perfluoroethane (C2F6) gas tamponade. A few days after the surgery, C2F6 was observed in the anterior chamber of both patients. Two months after gas tamponade, opacification of the anterior surface of the IOL was observed. The third patient was a 74-year-old woman, who underwent a combined Descemet membrane endothelial keratoplasty (DMEK) and FIL SSF IOL implantation. Two rebubblings with sulfur hexafluoride (SF6) retreatments were required due to corneal graft detachment. One month later, an opacification of the anterior surface of the IOL was observed. Explantation with implantation of iris-claw IOL was decided, which resulted in an improvement of BVCA. Analysis of the IOL showed a positive Von Kossa staining, indicating calcification of the IOL. We performed a review of all the cases of FIL SSF IOL implantation in our centers. The overall rate of FIL SSF IOL opacification was 2.1% (3/140). Amongst patients treated with gas tamponade, the rate of opacification was 27.3% (3/11). Although FIL SSF IOL implantation appears to be an effective option for the treatment of aphakia, caution should be exercised regarding the risk of opacification following gas tamponade, especially since these patients are at risk of retinal detachment.

[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.

Refractive outcomes after DMEK: meta-analysis

In this meta-analysis and systematic literature review of refractive outcomes after Descemet membrane endothelial keratoplasty (DMEK), the extent of the refractive shift and an overview of reasons for refractive shift after DMEK are provided. The PubMed library was screened for articles containing the terms "Descemet membrane endothelial keratoplasty," "DMEK," "Descemet membrane endothelial keratoplasty combined with cataract surgery," "triple-DMEK" combined with "refractive outcomes," "refractive shift," and "hyperopic shift." The refractive outcomes after DMEK were analyzed and compared using a fixed and random effects model. The overall mean change of the spherical equivalent outcome when compared with the preoperative value in cases of DMEK or when compared with the preoperative target refraction in cases of DMEK combined with cataract surgery was +0.43 diopters (D) (95% CI, 0.31-0.55). When DMEK is combined with cataract surgery, a target refraction of -0.5 D is recommended to achieve emmetropia. Changes in the posterior corneal curvature are identified as the main cause of the refractive hyperopic shift.

New exploration of ions and fatty acids in hydrophilic acrylic intraocular lens calcification

PURPOSE

To conduct a new exploration and analysis of the ion and fatty acid levels of a medium in which calcified hydrophilic intraocular lenses (IOLs) are present.

SETTING

Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China.

DESIGN

Retrospective, laboratory observational case series.

METHODS

11 patients (11 eyes) who had implantation of foldable hydrophilic acrylic posterior IOLs were found to have opacification of the IOLs. In vivo and in vitro analyses included the evaluation of patients' clinical characteristics, microscopy, histological staining, energy dispersive X-ray spectroscopy (EDS), the ion level of the aqueous humor (AH) and preserving fluid (PF), and the fatty acid content of AH.

RESULTS

10 of 11 cases were female with unilateral opacification, and 7 cases had both-eye cataract surgery, including 1 first eye and 6 second eyes with IOL opacification. 4 types of similar serial numbers were counted. The analysis of AH showed that the concentrations of phosphorus and silicon were elevated but that of calcium decreased, and an increased level of silicon was detected in 3 random PFs. The palmitic (C16:0) and stearic (C18:0) fatty acids were higher than the others in the AH. The EDS confirmed that the IOL surface deposits were composed of calcium, phosphate, and a small amount of silicon.

CONCLUSIONS

More silicon and higher C16:0 and C18:0 were found in the AH of patients with IOL opacification. New ideas and avenues have been proposed in the study of IOL opacification.

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.

Late postoperative opacification of a new type hydrophilic acrylic intraocular lens

Background

To report the clinical consequences and laboratory characteristics of late postoperative opacification of a hydrophilic acrylic intraocular lens (US-860UV IOL) as well as the prognosis of IOL replacement.

Methods

Forty medical records (42 eyes) of patients with US-860UV IOL opacification reporting decreased or lost vision who underwent IOL explantation between 2017 and 2019 were reviewed. Explanted IOLs were analyzed by slit-lamp examination, confocal microscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) at the Shandong Key Laboratory of Ophthalmology, Shandong Eye Institute, Shandong First Medical University, and Qingdao University of Science and Technology, Qingdao, China.

Results

The mean age of the 40 patients was 74.83 ​± ​7.57 (63-92) years. The mean interval between cataract surgery and diagnosis of opacification was 32.38 ​± ​8.76 (17-48) months. Systemic diseases were found without statistical correlations, the most frequent being arterial hypertension, coronary heart disease, and diabetes mellitus. Visual acuity improved from 1.42 ​± ​1.03 to 0.31 ​± ​0.16 (logMAR) after IOL replacement. SEM, EDS and alizarin red staining showed uniformly distributed, diffuse, milk-white opacification, with calcium and phosphorus deposits on the optic and haptic surfaces that could be dissolved in 1% HCl.

Conclusions

Calcium and phosphorus deposition was the main cause of hydrophilic acrylic US-860UV IOL opacification. IOL replacement can safely and effectively improve the visual acuity of patients.

The effect of hypotensive drugs on intraocular lenses clarity

OBJECTIVES

To assess the effect of hypotensive drugs on light absorbance, discoloration, opacification and precipitate formation of IOLs.

METHODS

In this laboratory study, four types of IOLs (two hydrophilic-acrylic-L1 and L2, and two hydrophobic-acrylic-B1 and B2) were soaked in solutions containing Timolol-maleate 0.5%, Dorzolamide 2%, Brimonidine-tartrate 0.2%, Latanoprost 0.005%, Brimonidine-tartrate/Timolol-maleate 0.2%/0.5% and Dorzolamide/Timolol-maleate 2%/0.5%. Non-treated IOLs and IOLs soaked in balanced salt solution (BSS) served as controls. All Treated lenses were sealed in containers and placed in an oven at 82 degrees Celsius for 120 days. Each IOL was examined using four different techniques: light microscopy imaging, light absorbance measurements at 550 nanometers through the optic's center, assessment of by a scanning electron microscope (SEM), and energy dispersive Xray spectrometry (EDX).

RESULTS

Ninety-eight IOLs were included. All BSS-soaked IOLs appeared clear with no significant discoloration or precipitate-formation. Light absorbance in these lenses was comparable to that of non-soaked, non-heated IOLs. No calcium or phosphate were detected in either of these groups. Light absorbance differed significantly between the four treated IOL types. The drops most affecting light absorbance differed between IOLs. Gross examination revealed brown and yellow discoloration of all IOLs soaked in Dorzolamide and Brimonidine-tartrate solutions, respectively. SEM demonstrated precipitates that differed in size, morphology and distribution, between different IOL-solution combinations. EDX's demonstrated the presence calcium and phosphor in the majority of precipitates and the presence of sulfur in brown discolored IOLs.

CONCLUSIONS

In vitro, interactions between hypotensive drugs and IOLs induce changes in light absorbance, discoloration and precipitate formation.

Clinical Characteristics of Patients with Intraocular Lens Calcification after Pars Plana Vitrectomy

AIM

To determine the clinical risk factors that may increase the occurrence of intraocular lens (IOL) calcification in patients who had undergone pars plana vitrectomy (PPV).

METHODS

The medical records of 14 patients who underwent IOL explantation due to clinically significant IOL opacification after PPV were reviewed. The date of primary cataract surgery, technique and implanted IOL characteristics; the time, cause and technique of PPV; tamponade used; additional surgeries; the time of IOL calcification and explantation; and IOL explantation technique were investigated.

RESULTS

PPV had been performed as a combined procedure with cataract surgery in eight eyes and solely in six pseudophakic eyes. The IOL material was hydrophilic in six eyes, hydrophilic with a hydrophobic surface in seven eyes and undetermined in one eye. The endotamponades used during primary PPV were C2F6 in eight eyes, C3F8 in one eye, air in two eyes and silicone oil in three eyes. Two of three eyes underwent subsequent silicone oil removal and gas tamponade exchange. Gas in the anterior chamber was detected in six eyes after PPV or silicone oil removal. The mean interval between PPV and IOL opacification was 20.5 ± 18.6 months. The mean BCVA in logMAR was 0.43 ± 0.42 after PPV, which significantly decreased to 0.67 ± 0.68 before IOL explantation for IOL opacification (p = 0.007) and increased to 0.48 ± 0.59 after the IOL exchange (p = 0.015).

CONCLUSIONS

PPV with endotamponades in pseudophakic eyes, particularly gas, seems to increase the risk for secondary IOL calcification, especially in hydrophilic IOLs. IOL exchange seems to solve this problem when clinically significant vision loss occurs.

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.

Specifying Risk of Intraocular Lens Opacification After Endothelial Keratoplasty for Different Intraocular Lens Models: A Retrospective Monocentric Cohort Study

PURPOSE

The aims of this study were to calculate the specific risk of opacification for different intraocular lens (IOL) models and to determine whether differences exist, even between lenses made of similar acrylic materials.

METHODS

This is a retrospective cohort study of all patients who underwent endothelial keratoplasty (EK), either after or in conjunction with cataract surgery, from June 2009 to October 2020 at Fundación Jiménez Díaz Hospital.

RESULTS

Three hundred seventy-two eyes of 308 patients with a median follow-up of 856 days [interquartile range (IQR): 384-1570] were included, of which 128 IOLs were hydrophobic, 120 hydrophilic, and 124 unknown. 12.9% of IOLs opacified after a median of 466 days (IQR: 255-743). Visual acuity (VA) was significantly lower in the opacified IOL group [0.51 (IQR: 0.36-1.13)] compared with the nonopacified group [0.22 (IQR: 0.11-0.65)] ( P < 0.001). IOL explantation and exchange was performed in 10 eyes, in which VA improved markedly, from 1.75 (IQR: 0.99-3.00) to 0.60 (IQR: 0.36-0.86) ( P = 0.004). IOL material and opacification events were not independent ( P < 0.001). Significant differences were found between the Akreos ADAPT AO and MI60P models and the Asphina 409M model ( P = 0.022). No significant differences were found in the opacification ratio for hydrophilic IOLs in the clinical diagnosis ( P = 0.11), the type of EK ( P = 0.25), the rebubbling rate ( P = 0.44), or the tamponade used ( P = 0.36).

CONCLUSIONS

Hydrophilic lenses should be avoided in patients at risk of requiring EK. It is important to know the probability of opacification of each IOL model to balance risk and benefits when planning an EK procedure because not all lenses opacify equally. Opacification is an unwanted event with a negative impact on VA, making IOL explantation and exchange the only viable treatment, although one that is not without risks.

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.

Laboratory and Clinical Experience With a Diffractive Trifocal Intraocular Lens Sutured to an Artificial Iris

PURPOSE

To determine in vitro, using a translational research approach before realizing the procedure in a patient with iatrogenic aphakia and partial aniridia, whether suturing a trifocal intraocular lens (IOL) to an artificial iris degrades the IOL's optical quality.

METHODS

Optical quality was analyzed by measuring the modulation transfer function (MTF) at a 3-mm aperture and at 50 and 100 lp/mm spatial frequencies. The FineVision Pod F GF IOL (PhysIOL) was assessed in two powers: two +20.00 diopters (D) (20A and 20B IOLs) and two +30.00 D (30A and 30B IOLs). The IOLs' decentration in relation to the artificial iris's center was evaluated. The laboratory results provided empirical evidence in the informed consent for surgical intervention in a patient with iatrogenic aphakia and iris defect in one eye. Clinical results were measured using the parameter of corrected distance visual acuity plus a patient self-assessment of the cosmetic appearance of the operated eye.

RESULTS

The 20A and 20B IOLs demonstrated a mean MTF reduction of up to 1.1%, whereas the 30A and 30B IOLs showed a decrease of up to 5.2% for both spatial frequencies. All lenses showed good centration levels. In the clinical case, the patient showed corrected distance visual acuity, distance-corrected near visual acuity, and distance-corrected intermediate visual acuity of 0.20, 0.20, and 0.22 logMAR, respectively. The patient was satisfied with the cosmetic outcome.

CONCLUSIONS

There was merely a slight reduction in trifocal IOL optical quality after it was sutured to an artificial iris. Clinically, the combined implantation of the artificial iris and FineVision IOL provided good functional and cosmetic outcomes. [J Refract Surg. 2022;38(1):61-68.].

Nisin-based antibacterial and antiadhesive layer-by-layer coatings

Some removable medical devices such as catheters and cardiovascular biomaterials require antiadhesive properties towards both prokaryotic and eukaryotic cells in order to prevent the tissues from infections upon implantation and, from alteration upon removal. In order to inhibit cell adhesion, we developed ultrathin hydrated Layer-by-Layer (LbL) coatings composed of biocompatible polyelectrolytes, namely chondroitin sulfate A (CSA) and poly-l-lysine (PLL). The coatings were crosslinked with genipin (GnP), a natural and biocompatible crosslinking agent, to increase their resistance against environmental changes. In order to confer antibacterial activity to the coatings, we proceeded to the electrostatically-driven immobilization of nisin Z, an antimicrobial peptide (AMP) active against gram-positive bacteria. The nisin-enriched coatings had a significantly increased anti-proliferative impact on fibroblasts, as well as a strong contact-killing activity against Staphylococcus aureus in the short and long term.

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.

Microscopic Characteristics of Late Intraocular Lens Opacifications

CONTEXT.—

The increases in overall life expectancy and in lens surgeries performed on younger patients have resulted in a significant increase in the anticipated duration of artificial intraocular lenses (IOLs) in the eye. Thus, the physicochemical properties of the IOL become a critical issue, and several types of postoperative IOL opacifications have been reported.

OBJECTIVE.—

To describe the microscopic characteristics of opacified IOLs. Glistenings and subsurface nanoglistenings are fluid-related phenomena developing mainly in hydrophobic acrylic IOLs and are associated with aqueous influx into the IOL matrix. Calcification presents in hydrophilic acrylic or silicone IOLs as deposits of hydroxyapatite or other phases of calcium. Snowflake degeneration is less common, and it manifests in older polymethyl methacrylate IOLs.

DATA SOURCES.—

PubMed and ScienceDirect databases were searched for the following keywords: intraocular lens, IOL, cataract surgery, phacoemulsification, opacification, glistening, subsurface nanoglistenings, calcification, snowflake degeneration. English-language articles published up to October 15, 2019 were included in the study. The manuscript contains mainly a literature review; however, it was supplemented with original investigations from the David J. Apple International Laboratory for Ocular Pathology.

CONCLUSIONS.—

Glistenings and subsurface nanoglistenings should be evaluated in a hydrated state and at room temperature; they manifest as microvacuoles sized from 1.0 to greater than 25.0 μm and less than 200 nm, respectively. Calcification deposits are situated on or underneath the surface of the IOL and can be stained with a 1% alizarin red solution or with the von Kossa method. Snowflake degeneration manifests as "particles" or "crystals," causing whitish IOL discoloration. Scanning electron microscopy or energy dispersive X-ray spectroscopy may improve the diagnostic accuracy.

Clinical features of red blood cell-coated intraocular lens after breakthrough vitreous hemorrhage secondary to neovascular age-related macular degeneration

PURPOSE

To investigate the incidence and clinical features of red blood cell (RBC)-coated intraocular lens (IOL) in breakthrough vitreous hemorrhage (VH) with subretinal hemorrhage (SRH) secondary to neovascular age-related macular degeneration (nAMD).

SETTING

Seoul National University Bundang Hospital, Seongnam, Korea.

DESIGN

Retrospective cohort analysis.

METHODS

A total of 30 patients diagnosed as breakthrough VH with SRH in nAMD who underwent pars plana vitrectomy were included in this study. Demographics and clinical characteristics of the subjects, visual acuities, and SRH sizes measured as disc diameters were analyzed. The correlation analysis between SRH size and absorption duration of RBC-coated IOL were performed.

RESULTS

Out of 30 eyes in 30 patients, RBC-coated IOLs were observed in 11 patients (37%). Appearance of RBC-coated IOLs was noted 1 month postoperatively, and the mean duration of SRH absorption was 8.6 ± 2.6 months. SRH sizes were significantly different between eyes with RBC-coated IOL and clear IOL (62.8 ± 20.7 vs 27.4 ± 14.2, P < .001). There was definite correlation between SRH size and absorption duration of RBC-coated IOL (correlation coefficient 0.899, P < .001, R2 = 0.831). There were no statistically significant differences according to age, sex, laterality, underlying medical conditions, preoperative lens status, history of antivascular endothelial growth factor treatment, and visual acuities. The degenerated RBC on the surface of IOL was confirmed by electron and light microscopy.

CONCLUSIONS

RBC-coated IOL could develop after vitrectomy surgery for breakthrough VH with massive SRH secondary to nAMD, and it can be confused with IOL opacification. Because it spontaneously disappears gradually, observation without IOL removal is warranted.

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.

Delayed postoperative opacification of three hydrophobic acrylic intraocular lens: A scanning electron microscopic and energy dispersive spectroscopic study

Purpose:

The aim of this study was to report scanning electron microscopic (SEM) and energy dispersive spectroscopic (EDS) findings of three specimens of opaque hydrophobic acrylic intraocular lens (IOL) explanted in delayed postoperative period for visual indications.

Methods:

Clinical data and photographs from each subject were obtained. Explanted IOLs were examined under gross and light microscopy followed by SEM coupled with EDS.

Results:

All three subjects underwent IOL implantation following senile cataract extraction at an average age of 64.3 ± 0.3 years, and the IOLs were in situ for a duration of 11.3 ± 4.04 years. The IOL explantation and exchange were done due to late postoperative opacification of the IOL and significant visual deterioration. The milky iridescent opacity affected the full thickness of IOL optics in the first two specimens and in the third only two surfaces were involved. SEM detected surface cracks in the first specimen, typical conglumated surface, pores and accumulation of crystals with surface deposit of nano-particles on the second specimen and uneven surface erosion in the third specimen. SEM detected mainly sodium (Na) and chloride (Cl) spikes. All patients recovered normal vision following IOL exchange.

Conclusion:

SEM features of the IOL optics and absence of calcium and phosphate spikes in EDS and other findings were consistent and suggestive of hydrolytic biodegradation of hydrophobic acrylic IOL polymer in ocular media and was responsible for delayed postoperative opacification of the hydrophobic IOLs and visual loss.

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.

Laboratory evaluation of higher-order aberrations and light scattering in explanted opacified intraocular lenses

Background

Intraocular lens (IOL) calcification is a serious condition that can only be treated by removing the clouded lens. Since explantation bears the risk of complications, it is often deferred until the patient finds the symptoms intolerable. Usually, as the IOL opacifies, visual acuity is minimally affected early on. In this study, we assessed the impact of IOL opacification on optical quality.

Methods

We analyzed ten opacified explanted IOLs (Oculentis GmbH). Wavefront aberrations were obtained with a SHSOphthalmic device (Optocraft GmbH), which features a Hartmann-Shack sensor. The root mean square (RMS) of higher-order aberrations (HOAs) was compared. The effect of calcification on image quality was assessed through the Strehl ratio (SR). We detected light scattering with a C-Quant (Oculus GmbH) and expressed it as a straylight parameter.

Results

At 2 mm, 3 mm and 4 mm, the mean RMS (±standard deviation) was 0.033 μm (±0.026 μm), 0.044 μm (±0.027), and 0.087 μm (±0.049), respectively. The mean SR value was 0.81 ± 0.15 at 3 mm, with four IOLs showing a nearly diffraction-limited performance, but in two explants, opacification precluded reliable measurements. Increased straylight was found in all opacified IOLs with a mean value of 150.2 ± 56.3 deg²/sr at 3 mm.

Conclusions

We demonstrated that IOL opacification induces HOAs. However, the RMS remained low, which resulted only in a slight reduction of the SR-derived optical quality. On the other hand, we found a severe straylight elevation in the opacified lenses, which may result in dysphotopsia, such as glare, and subjective complaints, despite good visual acuity.

[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.

Analysis of opacification patterns in intraocular lenses (IOL)

Objective

Intraocular lens (IOL) opacification may cause severe visual impairment. The pathogenesis remains unclear. The aim of this study was to analyse opacification patterns in different IOLs. Therefore, this multicentre, retrospective, observational study was conducted at Ludwig-Maximilians-University, Munich, Germany and University-Hospital Basel, Switzerland.

Methods and analysis

In this study, 75 opacified IOLs were identified and classified after extraction. Macroscopical photo documentation, light and electron microscopic analysis were done.

Results

68 acrylic-hydrophilic single-piece-IOLs, 1 acrylic-hydrophilic 3-piece-IOL, 6 acrylic-hydrophobic 3-piece-IOLs were extracted. The dataset comprised IOLs known for opacification and IOLs not having been reported yet. 67 IOLs showed a fine-granular and 8 IOLs a crust-like opacification pattern. According to literature, 62 of the fine-granular opacified IOLs were graded into type 1 (processing/packaging-induced primary opacification) and 13 into type 2 (secondary opacification of unknown aetiology). The anterior surface of the IOLs was affected in all 75 IOLs, the posterior surface only in 23 cases. Of all 67 fine-granular IOLs, 43 had a central defect and 21 had a zone without opacification (clear islet).

Conclusion

In our series, the morphology of IOL opacification did not follow the existing pathogenetic classification that strictly discriminates between primary and secondary causes. Fine-granular IOL opacification occurs with similar patterns in both type 1 and type 2 IOL opacification, while a crust-like pattern was only detected in type 2 IOL opacifications. Consequently, susceptibility of an IOL to opacification is caused by a multifactorial combination of material and processing properties as well as individual (pathological) conditions of the patient.

A review of late intraocular lens opacifications

PURPOSE OF REVIEW

Phacoemulsification cataract surgery is one of the most commonly performed surgical procedure worldwide. In the majority of cases, intraocular lenses (IOLs) are implanted. Due to the increasing life expectancy and the fact that cataract surgery is performed in earlier stages, the anticipated IOL duration in the eye has increased over the last decades. The aim of this study was to review the types and describe the characteristics of late intraocular lens opacifications.

RECENT FINDINGS

Calcification was the most commonly reported type of opacification in hydrophilic IOLs; it usually negatively impacted the visual function and required IOL explantation. Glistening manifested in hydrophobic acrylic lenses and was frequent in some IOL models. In most cases glistening and subsurface nanoglistenigs do not lead to a decline in visual acuity or require IOL exchange. Current studies indicate that fluid-related phenomena may induce straylight, leading to a decrease of comfort and quality of vision.

SUMMARY

Several reports on late IOL opacifications have been published in recent years. In some cases, particularly in glistening, the development of the opacifications might be related to IOL aging. The influence of the fluid-related microvacuoles on the quality of vision requires further research.

Intraocular Lens Opacification Following Silicone Oil Endotamponade

BACKGROUND AND OBJECTIVE

To report cases with intraocular lens (IOL) opacification following silicone oil (SO) endotamponade.

PATIENTS AND METHODS

Medical charts of 32 eyes with IOL opacification were evaluated retrospectively. All eyes had rhegmatogenous retinal detachment and had a history of previous hydrophilic acrylic IOL implantation. All patients underwent vitrectomy with SO endotamponade. Clinical features of all cases and the results of histochemical evaluation of explanted IOLs were reported.

RESULTS

The mean duration of SO endotamponade was 4.6 ± 2.0 months. The mean follow-up was 67.0 ± 23.5 months. The interval between phacoemulsification surgery and IOL opacification was 27.4 ± 18.3 months. With the exception of two eyes, all IOL opacification was detected during the follow-up period after SO removal. IOL exchange was performed in 12 eyes (37.5%). Histochemical analysis revealed significant calcification mostly on the surface of explanted IOL optics.

CONCLUSION

Vitreoretinal surgeons should be aware of that some hydrophilic IOLs may have the potential of opacification following SO endotamponade. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:37-43.].

[Opacification of intraocular lenses: laboratory and clinical findings]

Hintergrund

Das Spektrum der Komplikationen beim Einsatz von Intraokularlinsen (IOL) ist heute ein anderes als zur Zeit ihrer Einführung. Trübungen im IOL-Material werden vermehrt als Explantationsgrund in der Literatur beschrieben.

Ziel der Arbeit

Diese Arbeit soll einen Überblick über die verschiedenen Formen von IOL-Materialeintrübungen geben.

Material und Methoden

Die heute relevanten Formen von IOL-Materialeintrübungen und deren Auswirkungen auf die optische Abbildungsqualität wurden zusammengestellt.

Ergebnisse und Diskussion

Als Grund für eine Eintrübung steht bei hydrophilen IOL die Kalzifikation im Vordergrund, während bei hydrophoben IOL v. a. über die Entstehung sog. „Glistenings“ berichtet wird. Die meisten Materialeintrübungen beeinflussen verschiedene optische Parameter und führen zu einem erhöhten intraokularen Streulicht. Im Falle einer störenden Materialeintrübung besteht die einzige Therapieoption in einem Austausch der eingetrübten IOL.

A narrative review of intraocular lens opacifications: update 2020

The opacifications of intraocular lenses (IOLs) can significantly impact patients visual quality. Despite the identification of specific risk factors, manufacturing changes, opacifications are not eliminated. Likewise, more attention in recent studies was paid to possible new risk factors, however one of the most important purposes of the studies remains opacifications effect on visual performance, which could be disturbed in different aspects. The aim of this review is to discuss the main risk factors of IOLs opacification in particular IOL types, and its impact on vision quality. Different risk factors were discussed in the study, including the material of IOLs, the impact of the breakdown of blood-aqueous barrier (BAB), and certain surgeries that can be associated with opacification formation. Glistenings occur more often in a hydrophobic material, however, the changes in water content of the IOLs can significantly reduce the formation of glistenings. The studies showed a significant effect of intraocular injection of exogenous air or gas during Descemet-stripping endothelial keratoplasty, Descemet-stripping automated endothelial keratoplasty, Descemet membrane endothelial keratoplasty, and pars plana vitrectomy on calcification formation. It raises a concern, as the incidence of these surgeries is increasing. Visual acuity decreases significantly after the calcification in IOLs occurs, and it usually causes IOLs exchange. However, disability glare seems to be more affected in patients with IOLs, which were affected by glistenings than visual acuity. Disability glare is associated with increased levels of straylight, which was widely evaluated in recent studies and it was reported to be a susceptible measurement to detect the presence of IOLs pathology. For future researches, it should be noticed that disability glare and straylight are more appropriate in evaluating IOLs opacification effect on visual quality than visual acuity. While reviewing the main risk factors of IOLs opacifications particular attention must be paid on calcification occurrence in hydrophilic acrylic IOLs after surgeries with intraocular injection of exogenous air or gas.

Physicochemical Analysis of Sediments Formed on the Surface of Hydrophilic Intraocular Lens after Descemet's Stripping Endothelial Keratoplasty

An intraocular lens (IOL) is a synthetic, artificial lens placed inside the eye that replaces a natural lens that is surgically removed, usually as part of cataract surgery. The opacification of the artificial lens can be related to the formation of the sediments on its surface and could seriously impair vision. The physicochemical analysis was performed on an explanted hydrophilic IOL and compared to the unused one, considered as a reference IOL. The studies were carried out using surface sensitive techniques, which can contribute to a better understanding of the sedimentation process on hydrophilic IOLs’ surfaces. The microscopic studies allowed us to determine the morphology of sediments observed on explanted IOL. The photoelectron spectroscopy measurements revealed the presence of organic and inorganic compounds at the lens surface. Mass spectroscopy measurements confirmed the chemical composition of deposits and allowed for chemical imaging of the IOL surface. Applied techniques allowed to obtain a new set of information approximating the origin of the sediments’ formation on the surface of the hydrophilic IOLs after Descemet’s stripping endothelial keratoplasty.

Intraocular Lens Complications: Decentration, Uveitis-Glaucoma-Hyphema Syndrome, Opacification, and Refractive Surprises

As cataract surgery has evolved, intraocular lens (IOL) complications are rare. The purpose of this review was to report the incidence, diagnosis, and management of IOL decentrations, uveitis-glaucoma-hyphema (UGH) syndrome, IOL opacifications, and refractive surprises. Literature review was performed by searching PubMed, MEDLINE, EMBASE, and the Cochrane Controlled Trial Database and the reference lists of original studies as well as reviews. Intraocular lens decentrations and dislocations can appear at any time, particularly in patients with predisposing factors such as pseudoexfoliation, prior vitreoretinal surgery, or trauma. Recognizing when they require surgical intervention for UGH or to improve visual function is critical in limiting long-term sequela. Intraocular lens opacifications such as glistenings rarely require intervention, but others, such as subsurface nanoglistenings, calcifications, or discolorations, may require IOL exchange. Finally, despite our best efforts to enhance measurements and IOL calculations, refractive surprises still occur. Intraocular lens complications are uncommon with modern cataract surgery. A number of these complications require proper identification and care to optimize patient outcomes.

Variation in intraocular lens calcification under different environmental conditions in eyes with supplementary sulcus-supported lenses

Purpose

Analysis of explanted intraocular lenses (IOLs) from pseudophakic eyes with supplementary sulcus-supported IOLs.

Methods

In this laboratory investigation, ten supplementary and capsular bag IOLs were analyzed. All lenses were received between January 2012 and March 2018. Explants were examined morphologically with histological and electron microscopic techniques and patients’ medical history was evaluated. Additionally, we used a technique new to this field: Transmission Electron Microscopy and electron diffraction pattern analysis was performed to investigate the structure of the opacifying crystals in detail.

Results

Eleven lenses were explanted due to IOL opacification from seven polypseudophakic eyes: In three cases the supplementary lens calcified, in three cases the capsular bag IOL (both lenses analyzed) and in one case both IOLs (only the supplementary was received). Additional surgical procedures and comorbidities included pars plana vitrectomy or Descemet stripping endothelial keratoplasty and diabetes mellitus. For each opacified lens, a varying layer of a Calcium phosphate beneath the optic surface was apparent. Crystal characterization revealed its composition to be Hydroxyapatite.

Conclusions and Importance

We report on a series of secondary calcification in lenses explanted from polypseudophakic eyes. In some cases, calcification occurred in the capsular bag lens, in other cases in the supplementary lens, or in both. The severity of the morphological change could be related to the comorbidities and the presence of surgery subsequent to the lens implantations. Detailed morphology of the opacifying crystals was revealed.

•

Intraocular lenses exhibited calcification in a series of polypseudophakic eyes.

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Pathology occurred in the capsular bag lens, the supplementary lens, or in both.

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Calcification was associated with different environmental factors.

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Depending on the factor, morphology and pattern of the opacity differed.

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Transmission Electron Microscopy revealed the opacifying crystals' ultrastructure.

Glistening formation in a new hydrophobic acrylic intraocular lens

Background

The formation of fluid-filled microvacuoles, termed glistenings, is a common complication of intraocular lenses (IOLs) made from hydrophobic acrylate. Using our well-established in-vitro laboratory method, we evaluated a new IOL material’s resistance to glistening formation.

Methods

An in-vitro stress test for glistening induction was performed on 20 samples of hydrophobic acrylic IOLs: ten of the new Eyecryl ASHFY600 (Biotech Vision Care, Ahmedabad, India) compared with ten samples of AcrySof IQ SN60WF (Alcon, Fort Worth, USA). The number of microvacuoles per square millimetre (MV/mm²) was evaluated in five sections of each IOL. The results for each model were compared and rated on a modified Miyata Scale for grading glistening severity.

Results

In all cases, glistening number was higher in the central section of the IOL optic than in the periphery. Mean number of MV/mm² was highest in the central part of the AcrySof IQ SN60WF, with 41.84 (±27.67) MVs/mm². The lowest number of glistenings was found in the five sections of the Eyecryl ASHFY600 with 0.52 (±0.24) MVs/mm². Mean value of the Eyecryl ASHFY600 IOL, using the Miyata Scale, was Zero.

Conclusion

In this in-vitro laboratory study, the new hydrophobic acrylic IOL showed a high resistance to microvacuole formation. Results from this in-vitro study suggest that glistening numbers will be low in clinical use in the Eyecryl ASHFY600.

Ray propagation imaging and optical quality evaluation of different intraocular lens models

PURPOSE

Ray propagation visualization and optical performance analysis of four different intraocular lenses (IOLs).

METHODS

In this laboratory study, four IOLs with different optical designs were assessed: a monofocal AcrySof IQ SN60WF [Alcon], a diffractive-refractive bifocal AcrySof IQ Restor SN6AD1 [Alcon], a diffractive trifocal AcrySof IQ PanOptix TFNT00 [Alcon], and a diffractive extended-depth-of-focus (EDOF) Symfony ZXR00 [Johnson&Johnson]. An experimental set-up with a water bath containing 0.01% fluorescein solution and monochromatic green laser light (532 nm) was used to visualize the propagation of light rays. Also, the optical performance of the IOLs was evaluated by measuring the modulation transfer function (MTF) values at a pupil sizes of 3.0 and 4.5 mm on the optical bench OptiSpheric® IOL PRO II (Trioptics GmbH, Germany).

RESULTS

Both the diffractive-refractive bifocal IOL and the EDOF IOL showed two defined foci for distance and near vision. In the diffractive trifocal IOL, three distinct foci for distance, intermediate, and near vision could be visualized.

CONCLUSIONS

The ray propagation visualization technique allows a qualitative assessment and comparison of light energy distribution between different IOL models. The measured Through-Focus Response (TFR) quantitatively confirmed the evaluated ray propagation behavior.