Opacification of hydrophilic acrylic intraocular lens attributable to calcification: investigation on mechanism

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.

Three-year outcomes of a novel toric intraocular lens implantation for moderate-high myopic astigmatism in phakic eyes

PURPOSE

To investigate the three-year visual, refractive outcomes and adverse events of the Eyecryl toric phakic IOL (pIOL) for moderate-to-high myopic astigmatism.

METHODS

This retrospective study included eligible patients who underwent refractive surgery in one or both eyes with Eyecryl toric pIOL for myopic astigmatism. The efficacy, safety, predictability, rotational stability, vector analysis, and adverse events were evaluated in patients with spherical refraction from - 4.50 to -17.00 diopters (D) and cylindrical refraction from - 0.75 to -5.50 D.

RESULTS

Fifty-two eyes of 28 patients were included in the study. The mean efficacy and safety index were 1.12 ± 0.35 and 1.38 ± 0.42, respectively. The mean manifest refraction spherical equivalent was - 10.06 ± 2.69 D and - 0.64 ± 0.61 D preoperatively and postoperatively at 36 months, respectively. The mean manifest astigmatism was - 2.06 ± 1.16 D and - 0.44 ± 0.48 D preoperatively and 36 months postoperative, respectively. During the final examination, 70% of the eyes showed an increase in CDVA of one or more lines compared to their preoperative state. There was a cumulative endothelial cell loss of 3.1% at 36 months postoperatively. One eye developed visually significant anterior subcapsular opacity, whereas another eye experienced pIOL opacification.

CONCLUSION

The Eyecryl toric pIOL demonstrated satisfactory visual acuity and refractive outcomes, as assessed by efficacy, safety and stability over a three-year period.

A unique late-onset intraocular lens opacification 23 years after implantation: a clinical and laboratory case report

We report an unusual, rare case of opacification of the hydrophilic acrylic intraocular lens (IOL) 23 years after the initial surgery with significant visual deterioration. Opacification of the hydrophilic acrylic IOL was primarily due to the formation of folds on the surface of the lens material, and less so due to calcium phosphate deposits. Calcification opacification can be attributed to recent events, as evidenced by deposits of dicalcium phosphate dihydrate (CaHPO42H2O) and octacalcium phosphate (Ca8H2(PO4)65H2O), both of which are transient calcium phosphate phases, converting hydrolytically to the thermodynamically most stable hydroxyapatite (Ca10(PO4)6(OH)2). To our knowledge, this case of hydrophilic acrylic IOL opacification is the only one that has been described so late, 23 years after cataract surgery.

[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.

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.

Explantation of a sutureless scleral fixated Carlevale intraocular lens due to calcification: a clinical and laboratory report

BACKGROUND

Hydrophilic intraocular lens opacification is a rare complication due to calcification. With current new surgical techniques, including lamellar endothelial keratoplasty and vitrectomies, this irreversible complication is becoming more common. In this case study, we present clinical and laboratory features of a case of Carlevale hydrophilic acrylic IOL calcification.

CASE PRESENTATION

Observational case report of a single incident case. An 83-year-old man was referred to our ophthalmic department complaining of right eye vision blurring for six months. Slit-lamp biomicroscopy revealed IOL opacification. Deposits of calcium phosphate were found both on the IOL's surface and inside it, according to thorough investigation using optical, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectrometry.

CONCLUSIONS

To the best of our knowledge, this is the first case to describe the laboratory evidence of Carlevale hydrophilic IOL calcification, suggesting possible explanation mechanisms based on underlying pathology and surgical technique. It reminds us that these findings suggest that physicians should be aware of possible hydrophilic IOL calcification.

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.

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.

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.

Intraocular lens explantation following cataract surgery: Indications, techniques, and video demonstrations

As techniques for modern cataract surgery have expanded and premium intraocular lens (IOL) use is now widespread, patient expectations are high. The need for IOL explantation, whilst still low, remains an ongoing issue. Intraocular lens explantation can be challenging for a number of reasons and as such we have introduced an additional technique to add to the surgeon's repertoire. Bimanual haptic stripping of fibrosis at the specific area where the haptic is adherent to the capsular bag is an effective strategy to aid in dissection of haptics without compromising the capsule or zonules. Given the challenges associated with IOL explantation, newly designed IOLs need to avoid these "sticking points" at which the IOLs interact with the fibrosed capsule. Techniques we have evolved and which are described below should assist anterior segment surgeons to facilitate IOL removal in an efficient and safe way.

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.

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.

Localized calcification of hydrophilic acrylic intraocular lenses after posterior segment procedures

PURPOSE

To describe the clinical and laboratory findings in a series of cases of hydrophilic acrylic intraocular lens (IOL) opacification after posterior segment procedures.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, USA.

DESIGN

Experimental study.

METHODS

Thirty hydrophilic acrylic IOLs were explanted after various posterior segment procedures (pars plana vitrectomy, intravitreal anti-vascular endothelial growth factor injections) because of localized central anterior surface and subsurface optic opacification associated with decreased visual function. Once received by the laboratory in the dry state or in fixative by the explanting surgeons, microscopic, histochemical (alizarin red), and surface analysis (scanning electron microscopy [SEM], energy-dispersive X-ray spectroscopy [EDS]) evaluations were performed on the IOLs. The surgeons were sent a questionnaire to obtain information pertinent to each case.

RESULTS

Of the 30 explanted IOLs, 9 hydrophilic acrylic designs from 7 different manufacturers were identified. Gross microscopy and light microscopy showed granular deposits in a dense round pattern of distribution within the margins of the capsulorhexis or pupil on the anterior surface/subsurface of the IOLs. The granules stained positive for calcium with alizarin red. On SEM coupled with EDS, the granular deposits were found to comprise calcium and phosphate.

CONCLUSIONS

A localized pattern of anterior surface/subsurface calcification was seen on hydrophilic acrylic IOLs from various manufacturers. The calcification resembled the pattern seen on calcified IOLs after anterior segment procedures using intracameral injections of air or gas. This calcification of hydrophilic acrylic IOLs is likely the result of blood-aqueous barrier breakdown from repeated intraocular procedures.

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.].

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.

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.

•

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

•

Calcification was associated with different environmental factors.

•

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

•

Transmission Electron Microscopy revealed the opacifying crystals' ultrastructure.

Light scattering levels from intraocular lenses extracted from donor eyes

PURPOSE

To assess light scatter levels of intraocular lenses (IOLs) extracted from donor eyes to understand straylight elevation documented earlier in pseudophakic population studies and identify potential sources of light scattering in IOLs.

SETTING

Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands.

DESIGN

Experimental study.

METHODS

Light scattering in 74 donor IOLs was measured with the C-Quant device adapted for in vitro analysis of IOLs. Straylight was assessed at a 2.5-degree and 7.0-degree scatter angle, and results were compared with the straylight of a 20-year-old crystalline lens, a 70-year-old crystalline lens, and a lens with cataract. To identify potential changes to the IOL material, the IOLs were examined with a light microscope and a slitlamp.

RESULTS

At 2.5 degrees and 7.0 degrees, the straylight parameter was 5.78 deg²/steradian (sr) ± 4.70 (SD) and 5.06 ± 4.01 deg²/sr, respectively. Forty-one percent of IOLs showed lower straylight than the 20-year-old lens. In 14%, the scattering intensity was higher than in the 70-year-old lens; none showed straylight comparable to that of the cataractous lens. Increased straylight was associated with surface deposits, snowflake-like degeneration, and glistenings. The incidence of IOL-related complications differed between the IOL groups.

CONCLUSIONS

Microscopic structural alterations of IOLs play a major role in straylight elevations in pseudophakic eyes. A clear correlation with degeneration and/or alteration of implanted IOLs was found. Although these IOL-related complications would likely not affect visual acuity, they give rise to straylight and thus can cause disability glare and other symptoms.

Assessment of straylight and the modulation transfer function of intraocular lenses with centrally localized opacification associated with the intraocular injection of gas

PURPOSE

To assess the optical quality of intraocular lenses (IOLs) explanted because of opacification after the intraocular injection of gas.

SETTING

David J. Apple Laboratory, Heidelberg, Germany.

DESIGN

Experimental study.

METHODS

Four hydrophilic acrylic IOLs were studied, each with a centrally localized round opacification pattern associated with the intraocular use of gas. Laboratory analysis included gross examination with a light microscope, followed by alizarin and von Kossa staining. Optical quality was assessed by examining the modulation transfer function (MTF) and straylight. Results were compared with those of a control IOL and normative data for straylight of the crystalline lens. The following parameters were derived from image analysis: opacified surface fraction, light loss in the opacified surface, and the area and number of granules. The relationship between straylight increase and those parameters was studied.

RESULTS

Fine granules were identified on the IOL surface and subsurface. The granules stained positive for calcium, and the MTF levels of 2 IOLs dropped markedly. The other 2 showed relatively minor changes. The straylight was extremely increased in 3 IOLs up to (and above) a level of that of a cataractous lens. A proportional relationship was found between straylight and the morphological parameters from image analysis.

CONCLUSIONS

Intraocular lenses with centrally localized opacification have a strong potential for deteriorating optical performance. However, the optical quality might differ depending on the morphology of opacification. A serious straylight increase was found in most of these IOLs, suggesting that affected patients may suffer from glare-related symptoms.

Clinical and material degradations of intraocular lenses: A review

PURPOSE

To review the published scientific literature concerning clinical and material degradations of intraocular lenses after implantation in cataract surgery.

METHODS

A search was undertaken using the following databases: CENTRAL (including Cochrane Eyes and Vision Trials Register; The Cochrane Library: Issue 2 of 12 February 2019), Ovid MEDLINE (R) without Revisions (1996 to February week 2, 2019), Ovid MEDLINE (R) (1946 to February week 2, 2019), Ovid MEDLINE (R) Daily Update 19 February 2019, MEDLINE and MEDLINE non-indexed items, Embase (1980-2019, week 7), Embase (1974-2019, 19 February), Ovid MEDLINE (R) and Epub Ahead of Print, in-Process & Other Non-Indexed Citations and Daily (1946 to 19 February 2019), Web of Science (all years), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrial.gov) and the WHO International Clinical Trials Registry Platform (www.who.int/ictrp/search/en). Only published articles in English were selected. Search terms/keywords included 'IOL' or 'intraocular lens', combined with 'opacification', degradation, glistenings, nanoglistenings, whitening, transmittance, light scatter, discolouration/discoloration, performance, quality, material, biocompatibility, calcification, explantation and ultraviolet/UV radiation. Relevant in-article references not returned in our searches were also considered.

RESULTS

After review of the available articles, the authors included 122 publications in this review, based on the quality of their methodology and their originality. The studies included in this review were randomized controlled trials, cohort studies, case-controlled studies, case series, case reports, laboratory studies and review papers. Differing material degradations of intraocular lenses have been described and their associated pathophysiology studied. Reported anomalies include photochemical alterations, water vacuoles, internal and surface calcific deposits, surface coatings and discolouration. The nature of such changes has been shown to depend on the type of intraocular lenses material used and/or manufacturing processes and storage conditions employed. Changes in the intraocular lens can also be influenced by surgical technique, coexisting ocular pathologies and topical and systemic medications. The clinical significance of these degradations is variable, with some resulting in significant visual disturbance and the need for intraocular lens explantation and others producing only minimal visual impairments. Failure to recognize the precise nature of the problem may lead to unnecessary laser capsulotomy procedures.

CONCLUSION

Clinical degradations of intraocular lenses are uncommon but have been reported following the implantation of intraocular lenses made of differing biomaterials. Their correct identification and thorough investigation to determine the underlying cause is necessary for optimal patient management and the prevention of such problems. Choosing a lens made of a particular material may be important in patients with certain ocular conditions.

Late postoperative opacification of a hydrophobic acrylic intraocular lens AcryNovaTMPC 610Y

PURPOSE

To report late postoperative opacification of a hydrophobic acrylic intraocular lens (IOL) AcryNovaTMPC 610Y as well as the clinical consequences in patients 10 years after uncomplicated cataract surgery.

MATERIALS AND METHODS

Medical records were reviewed of 23 patients (26 eyes) with AcryNovaTMPC 610Y implantated between years 2005 and 2007. Next clinical examination was performed 10 years after surgery. We assessed best corrected distance visual acuity (BCDVA), contrast sensitivity (CSV-1000E) and relative opacity of IOL material, (OCULUS Pentacam HR). Results of BCDVA and Pentacam were analysed statistically. One explanted IOL was analysed using anterior segment OCT in vitro and spectroscopic method EDX (Energy-dispersive X-ray spectroscopy).

RESULTS

Opacification led to a statistically significant reduction in the best corrected distance visual acuity (BCDVA) = (0,95 ± 0,10) versus (0,87 ± 0,20) and to increase of IOL opacity only in some lenses but statistically significant in the average (6,37 ± 2,16)% versus value of (14,22 ± 5,87)%. In the explanted IOL we have documented structural changes of primarily hydrophobic raw material leading to property of hydrophilic one.

CONCLUSION

Some batches of AcryNovaTMPC 610Y were produced from raw material of poor quality which is the cause of its structural changes and its progressive opacification.

Late postoperative opacification of a hydrophilic-hydrophobic acrylic intraocular lens

PURPOSE

To report late postoperative opacification of a model of hydrophilic-hydrophobic acrylic intraocular lens (IOL) as well as the clinical consequences and laboratory characteristics.

SETTING

Department of Ophthalmology, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.

DESIGN

Retrospective case series.

METHODS

Medical records were reviewed of patients with Lentis LS-502-1 IOL opacification reporting visual loss who had IOL explantation between November 2013 and March 2015. Patients were identified in the emergency room or during regular follow-up visits. Explanted IOLs were analyzed at the Ophthalmic Explants Biobank, Vissum, Spain, or at the John A. Moran Eye Center, University of Utah, USA.

RESULTS

Twenty opacified IOLs were explanted from 19 patients. The mean interval between cataract surgery and diagnosis of opacification was 29.15 months ± 9.57 (SD) (range 6 to 45 months). Opacification led to a statistically significant reduction in corrected distance visual acuity (mean 0.86 ± 0.76 logMAR; P < .001) and occurred in 5.1% of the hydrophilic-hydrophobic acrylic IOLs implanted at the department. The most frequently associated medical conditions were arterial hypertension, diabetes, and glaucoma. All IOLs but 1 had a similar pattern of opacification, with yellowish diffuse opacification uniformly distributed and calcium deposits on the surface and/or subsurface of the optic and haptics and within the IOL material.

CONCLUSIONS

Opacification of the hydrophilic-hydrophobic acrylic IOL was found in a significant number of patients and had a significant effect on their vision. The opacification was attributed to primary calcification.

FINANCIAL DISCLOSURE

None of the authors has a financial or proprietary interest in any material or method mentioned.

Serial intraocular lens opacifications of different designs from the same manufacturer: Clinical and light microscopic results of 71 explant cases

PURPOSE

To report clinical findings and light microscopic results of 71 opacified hydrophilic acrylic intraocular lenses (IOLs).

SETTING

Vivantes Klinikum Neukoelln, Ophthalmology Department, Berlin, Germany.

DESIGN

Retrospective case series.

METHODS

Sixty-three patients (71 eyes) were referred to the clinic because of vision-impairing IOL opacification between December 2012 and September 2016 after routine cataract surgery elsewhere. The explanted IOLs were analyzed with light microscopy at the John A. Moran Eye Center (University of Utah, Salt Lake City, Utah, USA). Medical records were reviewed for visual acuity, comorbidities, and complications. Clinical follow up was 6 months.

RESULTS

Seventy-one opacified 1-piece or 3-piece hydrophilic acrylic IOLs (Lentis) of different designs from 2009 to 2012 (LS-502-1, LS-402-1Y, LS 312-1Y, LS-313-1Y, L-402, L-312) were found. Morphological findings were surface, subsurface, or deep calcifications of the IOL material. Explantation was performed 4 years ± 1.2 (SD) after initial phacoemulsification. The mean patient age was 78.6 ± 8.2 years. Ocular and systemic comorbidities were found without statistical correlation: the most frequent were diabetes, uveitis, and glaucoma. The preoperative mean corrected distance visual acuity changed from 0.63 ± 0.47 logarithm of the minimum angle of resolution (logMAR) to 0.20 ± 0.28 logMAR postoperatively (P < .001).

CONCLUSIONS

Different designs of IOLs by the same manufacturer, implanted between 2009 and 2012, developed late calcification with significant visual loss after routine cataract surgery. No medical, surgical, or ophthalmologic trigger could be determined. A manufacture issue might be the reason for the opacification.

Intraocular lens dystrophic calcification after trans-scleral diode laser treatment for a cyclodialysis cleft

Purpose

To describe a case of intraocular lens (IOL) dystrophic calcification as a complication of trans-scleral diode laser successfully used to treat a post-trabeculectomy cyclodialysis cleft.

Observations

A 76-year-old male with primary open angle glaucoma and pseudophakia (+19.0D Akreos M160L, Bausch & Lomb) was evaluated for vision impairment 4 months post-trabeculectomy complicated by a cyclodialysis cleft of his right eye. The patient was successfully treated with trans-scleral diode laser. After this treatment IOL opacification developed. Slit lamp examination and color photography of the anterior segment was performed prior to exchange of the opacified IOL. The explanted IOL underwent star testing, macroscopic imaging, phase contrast and scanning electron microscopy in addition to energy dispersive x-ray spectroscopy.

Confluent IOL deposits developed 4 months after trans-scleral diode laser treatment requiring IOL exchange. Star optical testing of the explanted IOL showed disruption of the diffraction image. An asymmetric pattern of deposition was congruent with the laser treatment quadrant. The subsurface location and discrete nature of the deposits were seen on phase contrast and electron microscopy. Energy dispersive x-ray spectroscopy demonstrated a predominance of calcium/phosphate in the deposits. We are unaware of previous reports in the literature of IOL dystrophic calcification occurring as a complication of trans-scleral diode laser treatment for a post-trabeculectomy cyclodialysis cleft.

Conclusion and importance

Delayed postoperative IOL dystrophic calcification in our case may have been from a combination of IOL biomaterial susceptibility to diode laser energy; damaged IOL material providing a nidus for calcific nucleation; and blood ocular barrier breakdown altering aqueous composition. We suggest that pseudophakia should influence the consideration of diode laser as treatment of a cyclodialysis cleft.

Calcification of a Rayner Centerflex 570H hydrophilic Acrylic Intraocular Lens following Vitrectomy for Retinal Detachment: A Clinicopathologic Report

Purpose

The case of a 71-year-old man who complained of progressive, unilateral visual blurring following vitrectomy for retinal detachment due to opacification of his Rayner Centerflex 570H intraocular lens (IOL) implant is reported. Intraocular lens exchange was carried out and the explanted lens analyzed. The same model lens in his fellow eye has remained clear.

Methods

Clinicopathologic case report.

Results

Scanning electron microscopy and energy-dispersive x-ray analysis confirmed the presence of hydroxyapatite deposits within the anterior surface of the IOL.

Conclusions

To our knowledge, this is the first clinicopathologic case report of calcification of this model IOL in an adult patient. The sequence of events, unilaterality and pathologic findings suggest secondary calcification, which could have been related to severe postoperative inflammation and associated blood-aqueous barrier breakdown.

Calcification of Hydrophilic Acrylic Intraocular Lenses With a Hydrophobic Surface: Laboratory Analysis of 6 Cases

PURPOSE

To investigate the nature and characteristic features of deposits causing opacification of intraocular lenses (IOLs) based on the examination of clinical findings using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) analysis.

DESIGN

Retrospective, observational case series.

METHODS

This is a multicenter study of 6 hydrophilic acrylic IOLs (Lentis LS-502-1; Oculentis GmbH, Berlin, Germany) with a hydrophobic surface that were explanted from 5 patients because of opacification. Three patients had an uncomplicated phacoemulsification. One patient underwent combined phacoemulsification and pars plana vitrectomy for retinal detachment and later silicone oil endotamponade owing to redetachment. The last patient had a pars plana vitrectomy and silicone oil instillation combined with phacoemulsification for tractive retinal detachment and diabetic retinopathy. The explanted lenses were submitted to our laboratory and were examined by SEM and EDX in order to identify the morphologic features and the composition of the deposits.

RESULTS

SEM and EDX analyses confirmed the presence of calcific deposits in the interior of the opacified hydrophilic IOLs, with a pattern showing the formation of lumps on the surface. The lumps were due to subsurface formation of calcium phosphate crystalline deposits. The crystallite clusters seemed to diffuse from the IOL interior to the surface.

CONCLUSIONS

We demonstrated the calcification pattern of the hydrophilic IOL (Lentis LS-502-1) with a hydrophobic surface. Although hydrophilic acrylic lenses have a hydrophobic surface, the development of calcification is a possible threat initiating from the hydrophilic subsurface of the IOLs.

Late Opacification of a Hydrophilic Acrylic Intraocular Lens in Europe

Purpose

To describe the clinical and microscopic findings in 2 different patients of 2 cases of late opacification of the hydrophilic acrylic intraocular lens (IOL) Ioflex.

Methods

Two eyes of 2 patients (73 and 74 years old) had an uneventful phacoemulsification surgery with implantation of the Ioflex IOL (power +21.5 D). At 5 years after surgery, a dense IOL opacification was detected in both cases with significant visual degradation. The IOLs were explanted and analyzed by microscopy.

Results

In both cases, a satisfactory visual recovery was achieved (corrected distance visual acuity of 6/9 and 6/12). Microscopic examination of the explanted IOLs revealed multiple small granules on the surface/subsurface of the lens. Although histochemical or surface analyses were not performed, the aspect appears consistent with a process of calcification of this lens design. Other findings included few surface contaminants, such as fibers, crystals that may correspond to dry viscoelastic and/or salt solutions, as well as pigments and dust-like deposits.

Conclusions

Opacification of the posterior chamber hydrophilic acrylic IOL Ioflex probably related to calcification can appear several years after its implantation and requires IOL exchange due to the significant visual loss induced. More studies are required to understand the causes of this complication.

Imaging characteristics of delayed surface calcification in hydrophilic intraocular lens models

We report two cases of opacified explanted intraocular lenses (IOL).The first lens was explanted from a cataract patient, then treated in vitro with trypsin/ethylene-diamine-tetra-acetic acid. The second hydrophilic acrylic IOL was explanted from a patient who had undergone sulphur hexafluoride (SF6) gas endotamponade surgery to repair a retinal detachment.

Experimental investigation on mechanism of hydrophilic acrylic intraocular lens calcification

PURPOSE

To construct a model simulating intraocular lens (IOL) opacification attributable to the formation of calcium phosphate deposits and to investigate the kinetics of deposit formation.

DESIGN

Prospective laboratory investigation.

METHODS

SETTING

Department of Ophthalmology, Medical School and Department of Chemical Engineering, Laboratory of Inorganic and Analytical Chemistry, University of Patras, Greece.

STUDY POPULATION

Three hydrophilic acrylic IOLs (26% water content) were placed inside a 10-mL double-walled thermostated reactor simulating the anterior chamber. Simulated aqueous humor was injected continuously into the reactor using a pump with variable speed.

OBSERVATION PROCEDURES

The observation of IOLs was carried out in situ daily by optical microscopy. Scanning electron microscopy and energy-dispersive radiographic spectroscopy were used for the identification of the morphologic features and the composition of the deposits.

RESULTS

The lenses were removed and inspected 5, 9, and 12 months after the initiation of the experiment. Investigation showed deposits of calcium phosphate crystallites in the interior of opacified IOLs. However, these deposits were not observed on the surface of the IOLs.

CONCLUSIONS

In agreement with earlier reports by our group and in the literature, IOL opacification is the result of calcification. It is suggested that the surface hydroxyl groups of the polyacrylic polymeric components of the IOLs are capable of inducing surface nucleation and crystal growth of calcium phosphates. However, most important is the finding that the calcification of IOLs is initiated from their interior through the development of sufficiently high local supersaturation, realized through the diffusion of calcium and phosphate ions.

Opacification of intraocular lenses implanted during infancy: a clinicopathologic study of 4 explanted intraocular lenses

OBJECTIVE

To report the clinicopathologic features of 4 opacified, single-piece, hydrophilic, acrylic intraocular lenses (IOLs) explanted from children who had undergone IOL implantation during infancy.

DESIGN

Observational case series.

PARTICIPANTS

Four IOLs explanted from 4 eyes of 3 children for visually significant opacification were included in the study.

METHODS

The clinical details of each case were obtained to look for possible risk factors for IOL opacification. The explanted IOLs were subjected to gross examination, staining by alizarin red 1% for calcium, scanning electron microscopy, and energy-dispersive x-ray spectroscopy (EDS). Levels of calcium and phosphorous were analyzed in the serum of all cases and in the aqueous humor of 1 case.

MAIN OUTCOME MEASURES

Morphologic features and composition of deposits.

RESULTS

Two cases had congenital cataract while one case was after bilateral lens sparing vitrectomy for retinopathy of prematurity. All underwent surgery during infancy with implantation of an IOL. The IOLs were explanted 8 months after surgery from 4 eyes of 3 children at the age of 17, 25, and 26. All the children received a single-piece hydrophilic acrylic IOL. The IOLs were in situ for an average duration of 13.86 months. The deposits were in the shape of a bicycle wheel on 3 IOLs and looked like fish eggs on 1 IOL. All deposits stained bright orange with alizarin red. On EDS, the deposits were found to be composed of calcium, phosphate, and silicone.

CONCLUSIONS

The morphologic features and composition of IOL deposits in 2 cases were similar to those of earlier reports in adults. The hydrophilic nature of the IOL material, sulcus implantation, and postoperative inflammation may be possible risk factors for opacification.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Spectroscopic study of explanted opacified hydrophilic acrylic intraocular lenses

PURPOSE

To report a detailed spectroscopic analysis of explanted hydrophilic acrylic intraocular lenses (IOLs) that were removed because of postoperative opacification of the lens optic.

METHODS

Thirteen Hydroview H60M (Bausch & Lomb Surgical) IOLs were explanted from 13 different patients on average 56 months after phacoemulsification and IOL implantation. All patients had decreased visual acuity because of a fine granularity of the optical surface of the IOLs. The surface was investigated by gross, microscopic, histochemical and scanning electron microscopic analysis, and the elemental composition of the opacified IOLs was determined by X-ray fluorescence spectroscopy (XRF). The spectrograms were compared to three different originally packed and never-implanted hydrophilic acrylic IOLs.

RESULTS

Light and scanning electron microscopy of the optical surface of explanted IOLs revealed multiple fine granular deposits varying in size and shape that were positive for alizarin red. XRF confirmed that the explanted IOLs contained not only the previously reported calcium and phosphorous (calcium apatite), chlorine, silicone, sodium, aluminum and magnesium but also iron, sulfur, potassium as well as lesser amounts of iodine, zinc, strontium and yttrium.

CONCLUSION

This is the first spectroscopic analysis determining the content of more than 10 elements of explanted and originally packed never-implanted hydrophilic acrylic IOLs. The possible origin of the different elements obtained from the spectrograms and their implications are discussed.

Softec HD hydrophilic acrylic intraocular lens: biocompatibility and precision

Intraocular lens development is driven by higher patient expectations for ideal visual outcomes. The recently US Food and Drug Administration-approved Softec HD^™ lens is an aspheric, hydrophilic acrylic intraocular lens (IOL). The hydrophilic design of the lens is optimized to address dysphotopsia while maintaining biocompatibility, optical clarity, resistance to damage, and resistance to biocontamination. Aspheric lenses decrease postoperative spherical aberration. The addition of the Softec lens provides clinicians with another option for IOL placement; however, randomized comparative studies of this lens to others already on the market remain to be completed.

Spectral analysis and comparison of mineral deposits forming in opacified intraocular lens and senile cataractous lens

This preliminary report was attempted to compare the chemical components of mineral deposits on the surfaces of an opacified intraocular lens (IOL) and a calcified senile cataractous lens (SCL) by vibrational spectral diagnosis. An opacified intraocular lens (IOL) was obtained from a 65-year-old male patient who had a significant decrease in visual acuity 2-years after an ocular IOL implantation. Another SCL with grayish white calcified plaque on the subcapsular cortex was isolated from a 79-year-old male patient with complicated cataract after cataract surgery. Optical light microscope was used to observe both samples and gross pictures were taken. Fourier transform infrared (FT-IR) and Raman microspectroscopic techniques were employed to analyze the calcified deposits. The curve-fitting algorithm using the Gaussian function was also used to quantitatively estimate the chemical components in each deposit. The preliminary results of spectral diagnosis indicate that the opacified IOL mainly consisted of the poorly crystalline, immature non-stoichiometric hydroxyapatite (HA) with higher content of type B carbonated apatites. However, the calcified plaque deposited on the SCL was comprised of a mature crystalline stoichiometric HA having higher contents of type A and type B carbonate apatites. More case studies should be examined in future.