Clinical features of 46 eyes with calcified hydrogel intraocular lenses

Qualitative and quantitative analysis of an explanted opacified hydrophilic IOL after over two years from cataract surgery

Opacification of hydrophilic intraocular lenses (IOLs) is an uncommon complication, that can appear after uneventful cataract surgery. We report a case of opacified Hydroview® IOL in a 76-year-old woman, with a previous history of pars plana vitrectomy with silicon oil tamponade in her right eye for a proliferative diabetic retinopathy, who developed an opacification of the IOL after over two years from a silicon oil/BSS exchange in combination with an uneventful phacoemulsification. The patient complained about a progressive decrease in her visual acuity. The slit-lamp examination confirmed the opacification of the IOL. Therefore, because of blurred vision, a combined procedure of explant and exchange of the IOL was performed in the same eye. Qualitative (Optic microscope, X-Ray powder Diffraction (XRD), Scanning Electron Microscopy (SEM)) and quantitative (Instrumental Neutron Activation Analysis (INAA)) analysis of the IOL material were performed. Here, our aim is to report the acquired data of the explanted Hydroview® H60M IOL.

Risk of Intraocular Lens Opacification After Endothelial Keratoplasty for Different Intraocular Lens Models: A Retrospective Single-Center 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.

Delayed surface opacification of a hydroview intraocular lens

The insertion of an intraocular lens during cataract surgery is routine but delayed opacification of hydrophilic foldable intraocular lenses (IOLs) has been increasingly noticed as a late post-operative complication. Such opacification may present with reduced visual acuity and can be diagnosed with slitlamp biomicroscopy. Lens explantation may be required. We report an 89-year-old female presenting with opacification of a Hydroview IOL and correlate the clinical findings of the lens in situ with the light microscopy of the explanted lens, as well as transmission electron microscopy (TEM), scanning electron microscopy (SEM) and elemental analysis. Pathological analysis of an explanted IOL may assist in a better understanding of the condition and may become relevant in medico-legal proceedings.

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.

A class of semiparametric cure models with current status data

Current status data occur in many biomedical studies where we only know whether the event of interest occurs before or after a particular time point. In practice, some subjects may never experience the event of interest, i.e., a certain fraction of the population is cured or is not susceptible to the event of interest. We consider a class of semiparametric transformation cure models for current status data with a survival fraction. This class includes both the proportional hazards and the proportional odds cure models as two special cases. We develop efficient likelihood-based estimation and inference procedures. We show that the maximum likelihood estimators for the regression coefficients are consistent, asymptotically normal, and asymptotically efficient. Simulation studies demonstrate that the proposed methods perform well in finite samples. For illustration, we provide an application of the models to a study on the calcification of the hydrogel intraocular lenses.

Efficient estimation of a linear transformation model for current status data via penalized splines

We propose a flexible and computationally efficient penalized estimation method for a semi-parametric linear transformation model with current status data. To facilitate model fitting, the unknown monotone function is approximated by monotone B-splines, and a computationally efficient hybrid algorithm involving the Fisher scoring algorithm and the isotonic regression is developed. A goodness-of-fit test and model diagnostics are also considered. The asymptotic properties of the penalized estimators are established, including the optimal rate of convergence for the function estimator and the semi-parametric efficiency for the regression parameter estimators. An extensive numerical experiment is conducted to evaluate the finite-sample properties of the penalized estimators, and the methodology is further illustrated with two real studies.

A Survey of Intraocular Lens Explantation: A Retrospective Analysis of 23 IOLs Explanted during 2005

Purpose

To evaluate the indications, lens styles, perioperative findings, and results of intraocular lens (IOL) explantation or exchange performed in the authors department in 2005.

Methods

The retrospective analysis comprised 22 patients (23 eyes). Twenty-one eyes had previous phacoemulsification and IOL implantation, one eye secondary aphakic IOL, and one eye phakic IOL implantation. The indications for IOL explantation/exchange and perioperative complications were evaluated. The best-corrected visual acuity (BCVA) before and after surgery was compared.

Results

Time from initial surgery to explantation/exchange varied from 1 to 121 months, median value was 46 months. The IOLs were explanted using local anesthesia and in 21 eyes replaced with new lens. Indications for IOL removal were opacification of the IOL in 12 eyes, malposition of the IOL in 5 eyes, postoperative refractive error in 2 eyes, recurrent toxic anterior segment syndrome in 1 eye, pseudophakic dysphotopsia in 1 eye, endothelial cell loss in phakic anterior chamber IOL in 1 eye, and visual discomfort with intraocular telescopic lens in 1 eye. The mean BCVA (decimal scale) before and after IOL explantation/exchange was 0.562±0.279 and 0.627±0.276, respectively. There was no significant difference in visual acuity before and after IOL exchange (Wilcoxon test).

Conclusions

The most frequent indications for IOL explantation/exchange were opacification of the IOL and IOL malposition. Surgeries were uneventful in most cases. Final visual results have been largely good. Long-term follow-up of patients with various types of IOLs should be maintained.

Penalized estimation for proportional hazards models with current status data

We provide a simple and practical, yet flexible, penalized estimation method for a Cox proportional hazards model with current status data. We approximate the baseline cumulative hazard function by monotone B-splines and use a hybrid approach based on the Fisher-scoring algorithm and the isotonic regression to compute the penalized estimates. We show that the penalized estimator of the nonparametric component achieves the optimal rate of convergence under some smooth conditions and that the estimators of the regression parameters are asymptotically normal and efficient. Moreover, a simple variance estimation method is considered for inference on the regression parameters. We perform 2 extensive Monte Carlo studies to evaluate the finite-sample performance of the penalized approach and compare it with the 3 competing R packages: C1.coxph, intcox, and ICsurv. A goodness-of-fit test and model diagnostics are also discussed. The methodology is illustrated with 2 real applications.

Etiology of surface light scattering on hydrophobic acrylic intraocular lenses

PURPOSE

To study the etiology of surface light scattering on hydrophobic acrylic intraocular lenses (IOLs).

SETTING

Alcon Research Laboratories, Fort Worth, Texas, USA.

DESIGN

Experimental study.

METHODS

Intraocular lenses were obtained from clinical explantations (n = 5), from human cadavers (n = 8), and from finished-goods inventory (controls). Surface light scattering was measured and imaged with the IOLs in various hydration states (dry, short-term wetted, and long-term hydrated) before and after proteins were quantified and removed. Selected IOL samples were analyzed with x-ray photoelectron spectroscopy, scanning electron microscopy (SEM) with energy-dispersion x-ray analysis, Fourier-transform infrared spectroscopy with attenuated total reflectance, and cryogenic SEM with a focused ion beam.

RESULTS

No inorganic deposits or organic changes were observed on any IOL surface. Under clinically relevant hydrated conditions, surface light-scattering intensity was independent of proteinaceous biofilm state (P≥.11). Instead, the hydration state of the IOLs significantly contributed to the intensity of surface light scattering (P<.001); clinically explanted and cadaver-eye IOLs (but not control IOLs) exhibited minimal scatter when dry, intermediate scatter when wetted, and maximum scatter when hydrated. Subsurface nanoglistenings with diameters less than a micron and with locations up to 120 μm from the surface of the IOLs were characterized by SEM with a focused ion beam and were identified as the source of the hydration-related surface light scattering.

CONCLUSION

Surface light scattering on hydrophobic IOLs was predominantly caused by hydration-related subsurface nanoglistenings within the acrylic IOL material.

Piggybacking technique for vitreous protection during opacified intraocular lens exchange in eyes with an open posterior capsule

We describe a surgical technique for the safe exchange of opacified 1-piece IOLs in eyes that have had a neodymium:YAG laser posterior capsulotomy. Initially, the opacified IOL is freed from the capsule adhesions using a dispersive ophthalmic viscosurgical device, which is also injected beneath the opacified IOL to protect the vitreous interface. The IOL is then brought into the anterior chamber. A new 3-piece clear IOL is injected before the opacified IOL is removed and is placed behind the opacified IOL, preventing the vitreous from prolapsing. The pupil is constricted pharmacologically, and the opacified IOL is removed through a standard 2.75 mm corneal incision using the hinge technique.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

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.

Time-dependent ROC analysis under diverse censoring patterns

In biomedical studies, statistical approaches based on the Receiver Operating Characteristic (ROC) analysis have been extensively used in the evaluation of classification performance of markers and construction of classifiers. In this article, we investigate time-dependent ROC approaches for censored survival data. While most existing studies have been focused on uncensored and right-censored data, insufficient attention has been paid to other censoring schemes. This study advances from existing studies by investigating more diverse censoring schemes and developing ROC measurements under such censoring. Both estimation and inference are investigated. We conduct simulation and find satisfactory performance of the proposed approaches. We apply the proposed approaches to two real data sets, compare the prognostic power of markers, and investigate whether their linear combinations have better prognostic performance. We also explore graphical tools that can assist diagnostics and efficiently monitor the classification performance.

Opacification of the intraocular lens implant following uneventful Descemet's stripping endothelial keratoplasty

A 74 year old pseudophakic patient developed opacification of a pre-existing intraocular lens implant following Descemet's stripping endothelial keratoplasty which may have been triggered by the presence of air in the anterior chamber.

Intraocular lens exchange through a 3.2-mm corneal incision for opacified intraocular lenses

Aim:

The aim was to evaluate visual and refractive results and complications of intraocular lens (IOL) exchange through a 3.2 mm corneal incision for opacified IOLs.

Materials and Methods:

This retrospective study comprised 33 eyes of 32 patients with IOL opacification requiring an IOL exchange between July 2003 and March 2007. Exchange surgery was performed through a 3.2-mm temporal clear corneal incision followed by implantation of a new foldable hydrophobic IOL. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), topographical astigmatism, and refractive cylinder were evaluated. Surgically induced astigmatism (SIA) was calculated and complications were recorded.

Results:

Opacification was observed in 25 eyes (76%) with Aqua-Sense, 3 eyes (9%) with Hydroview, 3 eyes (9%) with MemoryLens IOLs, and 2 eyes (6%) with DgR. The mean follow-up period was 36.54 months. An uneventful IOL exchange was achieved in 18 eyes (55%). Zonular dehiscence occurred in 9 eyes (27%), and posterior capsule tear developed in 4 eyes (12%). The mean preoperative BSCVA (mean ± standard deviation, decimal scale) was 0.13 ± 0.08 (mean: 20/150, range 20/2000 to 20/60) and improved to 0.63 ± 0.18 (mean: 20/32, range 20/60 to 20/20, P < 0.001). The mean SIA was 0.70 D. Seven eyes (21%) had 0.5 D or lower SIA.

Conclusion:

IOL exchange is a technically challenging procedure with potential risks of reversing the advantages of a prior small-incision cataract surgery. The use of a small corneal incision for IOL exchange could preserve the advantages of modern phacoemulsification surgery with acceptable SIA related to the procedure.

Analysis of surface whitening of extracted hydrophobic acrylic intraocular lenses

PURPOSE

To identify the cause of light scattering on the surface (ie, whitening) of extracted AcrySof intraocular lenses (IOLs).

SETTING

Department of Ophthalmology, Dokkyo Medical University, Tochigi, Japan.

METHODS

Dislocated IOLs extracted from 3 patients were stored and the IOL surfaces examined under light microscopy. The effect of whitening on visual function was evaluated by measuring light transmission with a spectrophotometer. To determine the cause of opacification, the IOLs were examined for calcium phosphate deposits using an electron probe X-ray microanalyzer. The IOL surface, including the presence of organic deposits and evidence of hydrolysis, was also examined by Fourier-transform infrared spectrophotometry. The IOLs were then dried, immersed again in physiological saline, and serially examined for changes in opacification.

RESULTS

The optic surfaces of all IOLs had opacification due to whitening. Light transmission in the visible range of 360 to 800 nm was 4% less than that of unused IOLs. The X-ray microanalysis showed no calcium phosphate deposits. Fourier-transform infrared spectrophotometry of the IOL optic material showed no evidence of hydrolysis. Opacification disappeared after the IOLs were dried and then reappeared over time when the IOL was immersed again in physiologic saline.

CONCLUSIONS

The findings strongly suggest that whitening of the hydrophobic acrylic IOL was due to trace water molecules that infiltrate the optic. Within the 3-dimensional network of the polymeric lens material, the molecules are too small to form observable voids but can form water aggregates of sufficient size to scatter visible light, causing opacification (ie, whitening).

Clinical efficacy and complications of intraocular lens exchange for opacified intraocular lenses

PURPOSE

To evaluate the clinical efficacy and complications of intraocular lens (IOL) exchange.

METHODS

A review of medical records was performed for 52 eyes that had undergone an IOL exchange due to IOL opacification. Surgical complications and their incidences were analyzed. The mean best corrected visual acuity (BCVA) after the IOL exchange was compared with the mean pre-exchange BCVA and with the mean BCVA after the initial IOL implantation. Prediction error of refraction and biometric data obtained for the IOL exchange were, if available, compared with those obtained for the initial IOL implantation. The prediction error for the IOL exchange, calculated from the biometric data obtained before the IOL exchange, was compared with that calculated from the measurements obtained before the initial IOL implantation.

RESULTS

The overall complication rates were low and no serious complications were found. The mean BCVA improved significantly after the IOL exchange and was not significantly different from that obtained after the initial IOL implantation. However, the refractive prediction for the IOL exchange was not as good as it was for the initial IOL implantation, which was thought to be related with difficulties in axial length (AL) measurements. Biometric data taken before the initial IOL implantation was associated with a significantly better refractive prediction than those taken before the IOL exchange.

CONCLUSIONS

IOL exchange was both efficacious and safe for visual recovery. However, IOL exchange was related with increased difficulty of predicting postoperative refraction; difficulties in AL measurements are the suggested cause.

Calcification of a hydrophilic acrylic intraocular lens: clinicopathological report

A 72-year-old man who had phacoemulsification with implantation of an Akreos Adapt Advanced Optics (AO) IOL in the left eye complained of blurring vision 4 months postoperatively. Multiple fine white granules were found within the IOL. Intraocular lens exchange was performed at 7 months, and the explanted IOL was sent for histopathological analysis. Diffuse fine white granules were seen within the explanted IOL material just beneath the surface; they were stained positive by alizarin red and the von Kossa method. Scanning electron microscopy confirmed the presence of calcium deposits in the IOL material. Blood and aqueous were drawn from the patient for biochemical analysis, and the results were normal. We believe this is the first clinicopathological report of calcification of the Akreos Adapt AO IOL.

Complications of foldable intraocular lenses requiring explantation or secondary intervention--2007 survey update

The tenth annual survey of complications associated with foldable intraocular lenses (IOLs) requiring explantation or secondary intervention was sent to members of the American Society of Cataract and Refractive Surgery and the European Society of Cataract and Refractive Surgeons. Preoperative data about visual acuity, patient signs and symptoms, and complications requiring IOL removal were evaluated. Complications were then tabulated for each of the following major foldable IOL groups: 1-piece (plate) silicone, 1-piece hydrophobic acrylic with haptics, 3-piece silicone, 3-piece hydrophobic acrylic, 3-piece hydrophilic acrylic (hydrogel), 3-piece unknown, multifocal acrylic, and multifocal silicone. One hundred forty-two surveys were returned for evaluation. Dislocation/decentration, incorrect IOL power, glare/optical aberrations, and IOL calcification were the most common reasons for removing foldable IOLs. Good surgical technique, accurate IOL power measurements, and high manufacturing standards for foldable IOL materials and designs are the most important factors in preventing complications.

Calcification of Hydroview H60M intraocular lenses: aqueous humor analysis and comparisons with other intraocular lens materials

PURPOSE

To compare the level of calcification on Hydroview H60M hydrophilic acrylic intraocular lenses (IOLs) (Bausch & Lomb) and other IOL materials.

SETTING

Omori Medical Center, Department of Ophthalmology, Toho University, Tokyo, Japan.

METHODS

The levels of calcification on Hydroview H60M hydrophilic acrylic IOLs, AcrySof SA60AT hydrophobic acrylic IOLs (Alcon Surgical, Inc.), Sensar AR40e hydrophobic acrylic IOLs (Advanced Medical Optics), ClariFlex (Advanced Medical Optics) silicone IOLs, and the MeniFlex ENV13 (Menicon) poly(methyl methacrylate) IOLs were compared in a calcium phosphate solution containing albumin. In a concentration-change experiment, the calcium and phosphate concentration levels were changed and the results observed by scanning electron microscopy.

RESULTS

The Hydroview H60M IOL had the largest amount of deposits. Small amounts of deposits were found on the other IOLs in the following decreasing order: AcrySof SA60AT, Sensar AR40e, ClariFlex, and MeniFlex ENV13. The amount of deposits on the Hydroview H60M IOLs was statistically significantly greater than the amount on the other IOLs (P<.01).

CONCLUSIONS

The hydrophilic acrylic IOLs (Hydroview H60M) had significantly higher amounts of calcified deposits than IOLs of other materials, indicating that hydrophilic acrylic IOLs easily accumulate calcified deposits in the body when the concentrations of calcium, phosphate, and albumin in the aqueous humor fluctuate as a result of a blood-aqueous barrier breakdown.

A New Classification of Calcification of Intraocular Lenses

OBJECTIVE

To define and classify the major types of intraocular lens (IOL) calcification.

DESIGN

Retrospective observational case series with clinicopathologic correlation.

PARTICIPANTS

More than 400 IOLs explanted because of opacification.

METHODS

The authors reviewed the clinical information and histologic findings of all IOLs that had been explanted because of opacification or calcification of the IOLs accessioned in their laboratory between January 1999 and December 2004.

MAIN OUTCOME MEASURE

The proposed mechanism that led to calcification of each IOL design.

RESULTS

Three major types of calcification were identified: (1) primary calcification, (2) secondary calcification, and (3) false-positive calcification or pseudocalcification. The primary form refers to calcification that is inherent in the IOL, that is, is based on possible inadequate formulation of the polymer, fabrication of the IOL, or issues with its packaging process. The calcification presumably occurs in otherwise normal eyes and generally is not associated with preexisting diseases. The secondary form refers to deposition of calcium onto the surface of the IOL most likely the result of environmental circumstances (e.g., changes in the aqueous milieu surrounding the implanted IOL associated with preexisting or concurrent diseases or indeed any condition that has disrupted the blood-aqueous barrier). By definition, it is not related to any problem with the IOL itself. The false-positive or pseudocalcification refers to those cases in which other pathology is mistaken for calcification or false-positive staining for calcium occurs.

CONCLUSIONS

When evaluating the pathogenesis and nature of IOL calcification in or on any given design, one should categorize it according to these types. Primary calcification is IOL related and the IOL should be withdrawn or modified to correct the problem. After the cause is identified and the lens is implanted again, patients should be followed up for up to 2 years to be sure the problem is alleviated. Secondary calcification is by definition not IOL related; it may occur with virtually all IOL designs implanted under various adverse circumstances. No IOL, hydrophilic or hydrophobic, is immune to secondary calcification. The false-positive form is recognized readily in the laboratory and this erroneous diagnosis is avoided.

Analysis of aqueous humor calcium and phosphate from cataract eyes with and without diabetes mellitus

Purpose

To compare the levels of calcium and phosphorus in the aqueous humor and serum of diabetics and non-diabetics.

Methods

We divided patients into two groups: seventy-six non-diabetic cataract patients and fifty-two diabetic cataract patients. The diabetic group was divided again into three subgroups: twenty-six patients with no diabetic retinopathy, thirteen patients with non-proliferative diabetic retinopathy, and thirteen patients with proliferative diabetic retinopathy. The authors compared the levels of calcium and phosphorus in the serum and aqueous humor of cataract patients. Statistic analysis was performed to form two comparisons: 1) a comparison between non-diabetics and diabetics and 2) a comparison among non-diabetics and the three subgroups of diabetics.

Results

In serum, calcium levels did not statistically differ between non-diabetics and diabetics. The phosphorus level was also not significantly different. In the aqueous humor, however, while calcium levels did not differ significantly, the phosphorus levels in diabetics were considerably higher than those in non-diabetics. When non-diabetics were compared to the three diabetic subgroups, calcium levels did not differ in serum or aqueous humor, but the phosphorus levels in diabetics with proliferative diabetic retinopathy were significantly higher than those in non-diabetics, diabetics without diabetic retinopathy, and diabetics with non-proliferative diabetic retinopathy.

Conclusions

The level of phosphorus in the aqueous humor and serum of diabetics was significantly increased, especially in diabetics with proliferative diabetic retinopathy. This result may be related to hydrophilic acrylic IOL opacification. Future studies regarding the pathogenic role of a high concentration of aqueous humor and serum phosphorus are required.

Misdiagnosis of Hydrophilic Acrylic Intraocular Lens Optic Opacification

PURPOSE

To report 8 patients with misdiagnosis of MemoryLens intraocular lens (IOL) late postoperative calcification and the resulting potentially avoidable procedures leading to secondary complications.

DESIGN

Retrospective interventional case series.

PARTICIPANTS

Eight patients with an opacified hydrophilic acrylic MemoryLens.

METHODS

Eight cases of MemoryLens IOL opacification that were originally misdiagnosed were reviewed. The following parameters were noted: baseline patient characteristics, time frame of IOL opacification, original misdiagnosis, subsequent surgical procedures, and postexplantation outcomes and complications. Two explanted lenses from this series were available for laboratory analyses. They underwent gross and light microscopic evaluation and scanning electron microscopy with energy-dispersive x-ray spectroscopy (EDS).

MAIN OUTCOME MEASURES

Patient parameters noted above. The IOLs were examined for distribution, structure, and composition of the deposits causing opacification of their optic components.

RESULTS

All 8 patients' IOLs were implanted between August 1999 and March 2000. Complaints of decreased visual function occurred 13 to 58 months after implantation. Half of the patients were initially diagnosed as having posterior capsular opacification and underwent neodymium:yttrium-aluminum-garnet laser capsulotomy. The other half were initially diagnosed with some form of vitreous involvement and underwent vitrectomies. Six of the 8 patients underwent subsequent lens exchanges, with 3 of them having postexchange complications including endophthalmitis, cystoid macular edema, and retinal detachment. Scanning electron microscopy with EDS confirmed the presence of calcified deposits on the surface of the 2 explants available for analysis. The deposits also stained positive for calcium.

CONCLUSIONS

Despite previous reports, misdiagnosis of MemoryLens IOL calcification leading to optic opacification still occurs. Not recognizing this process can lead to potentially avoidable surgical procedures and increased risk of complications after repeated interventions.

Early opacification of a single-piece hydrophobic acrylic intraocular lens after a triple procedure

We report a case in which the optic of a single-piece AcrySof acrylic (SA60AT, Alcon) intraocular lens (IOL) became opacified. A 64-year-old man had a triple procedure of vitrectomy, phacoemulsification, and IOL implantation for cataract and a dense vitreous hemorrhage in the left eye. The IOL was clear on the day after surgery, but by the third day, a dusty haze was observed on the surface due to the presence of numerous, small brown corpuscles. The IOL was removed and replaced with another SA60AT. No optic opacification occurred on the replacement IOL. Analysis of the explanted IOL indicated the presence of proteinaceous material but no calcium on the surface. Early postoperative opacification of a single-piece acrylic SA60AT IOL might occur in combined cataract and vitreous surgery, even in eyes in which the posterior capsule is intact and there are no operative complications.

Mineralization of radiation-crosslinked polyvinyl alcohol/polyvinyl pyrrolidone hydrogels

A study of the calcification of the polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) hydrogels during their exposure to a calcium chloride solution or a simulated body fluid has been carried out. On the basis of the experiments, using a two-compartment permeation cell, the diffusion of calcium ions and their subsequent deposition in the hydrogels were elucidated. Steady-batch experiments were also performed to further elaborate the deposition pattern and the types of calcium deposits. It was demonstrated that Fick's second law of diffusion can describe the diffusion of calcium ions through PVA/PVP hydrogels at 310 K. The diffusion coefficient was determined to be (4.4+/-0.1)x10(-10) m2/s and the partition coefficient for the hydrogels was 0.06. Formation of calcium deposits was noticed taking place both on the surface and inside the hydrogels. The deposits formed on the surface have flake morphology, while the deposits inside the hydrogels are more like globular aggregates. Both types of deposits have been characterized as being comprised calcium and hydroxyl ion deficient apatites with chloride ions the most likely substituting species at the hydroxyl sites.

Intraocular lens opacification after nonpenetrating glaucoma surgery with mitomycin-C

A 58-year-old woman had successful phacoemulsification with intraocular lens (IOL) implantation in January 2001. Two years later, nonpenetrating glaucoma surgery with mitomycin-C (MMC) 0.02% was performed for uncontrolled glaucoma. Two months later, opacification of the anterior IOL surface was observed. The IOL was removed and a hydrophobic acrylic AcrySof IOL (Alcon) implanted. The opacified IOL was studied by flame atomic absorption spectrometry, which showed the presence of calcium carbonate. A new IOL of the same model was placed in an aqueous solution with calcium carbonate and basic pH, and the same opacification developed. We hypothesize that the change in aqueous humor pH after glaucoma surgery and the characteristics of the IOL precipitated deposition of calcium.

Postoperative surface deposits on intraocular lenses in children

PURPOSE

To report the clinicopathologic features of 4 intraocular lenses (IOLs) composed of 3 different hydrophilic biomaterials explanted from children who had postoperative opacification of the IOL optic.

SETTING

David J Apple, MD, Laboratories for Ophthalmic Devices Research, John A. Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah, USA.

METHODS

The IOLs were explanted 20, 11, 22, and 25 months postoperatively from children aged 10, 3, 36, and 20 months old, respectively, at IOL implantation. Clinical data were obtained to correlate the findings with possible associated risk factors. The explanted IOLs were examined by gross and light microscopy. They were further analyzed with a stain for calcium, alizarin red 1%. Scanning electron microscopy and energy dispersive X-ray spectroscopy (EDS) were also performed.

RESULTS

The primary reason for cataract surgery in Case 1 and Case 2 was persistent hyperplastic primary vitreous (PHPV); 1 patient received a B-Lens IOL (Hanita) and the other a Centerflex IOL (Rayner). The primary reason in Case 3 was familial bilateral congenital cataract and in Case 4, rubella cataract; both patients received a Hydroview IOL (Bausch & Lomb). All 4 IOLs had surface deposits on the optic, but the morphology of the deposits on the B-Lens and Centerflex IOLs was different than that in previously reported cases. The deposits in all four cases stained positive with alizarin red and consisted of calcium and phosphorus when imaged with EDS.

CONCLUSIONS

Calcified deposits on 2 Hydroview IOLs explanted from children were similar to those seen in adults with the same IOL. The deposits on the B-Lens and Centerflex IOLs were probably secondary to a breakdown of the blood-aqueous barrier caused by preexisting PHPV.

Clinical presentation of intraocular lens schisis

PURPOSE

To analyze the clinical presentation and implications of cavity or schisis formation in the MemoryLens (CIBA Vision) intraocular lens (IOL) optic.

SETTING

Eye Department, Red Cross Hospital, Munich, Germany.

METHODS

This study was a retrospective chart review and slitlamp photography analysis of IOL schisis.

RESULTS

Four patients with IOL schisis were identified and their charts analyzed. Clinically, the schisis presented as a sharply demarcated round structure. The aspect was clear on coaxial illumination, but on tangential illumination the schisis area was opaque. Patients experienced glare, foggy vision, and deteriorated visual function or had no symptoms. One patient lost visual acuity, and the IOL was explanted.

CONCLUSIONS

Clinically, IOL schisis was easily differentiated from cases of IOL opacification due to calcification. The clinical implication was not uniform, ranging from no symptoms to great visual disturbance leading to explantation of the IOL. The cause of this complication remains unclear. A possible explanation is the impact of solvent-induced tensile stress on the IOL optic material during the manufacturing process.

Opacification of the Hydroview H60M intraocular lens: total patient recall

PURPOSE

To report the prevalence of intraocular lens (IOL) opacification and related clinical features in patients implanted with Hydroview IOL.

SETTING

Gloucestershire Eye Unit, Gloucestershire, United Kingdom.

METHODS

A total of 1330 eyes of 1265 patients who had cataract surgery with Hydroview IOL implantation between September 2000 and April 2001 were reviewed between April and October 2004. The visual acuity, visual symptoms, IOL status, and associated ocular comorbidity were recorded.

RESULTS

One hundred ninety-three (14.5%) of 1330 eyes had evidence of IOL opacification. A total of 56 (4.2%) had visually significant opacification and had IOL exchange. The prevalence of IOL opacification ranged from 1.1% in patients who had surgery in September 2000 to 36.3% in the December 2000 group. In eyes with IOL opacification, the visual symptoms were decreased vision (57%), glare (32%), and mistiness of vision (27%). One hundred forty-four eyes (75%) with IOL opacification had visual acuity of 6/12 or better; 21.5% of diabetic eyes had IOL opacification compared with 14.3% of nondiabetic eyes (P =.06); 20.5% of glaucomatous eyes had IOL opacification compared with 14.0% of nonglaucomatous eyes (P = .033).

CONCLUSIONS

This is the first large sample recall of patients implanted with the Hydroview H60M IOL. The overall prevalence of IOL opacification was 14.5%, with peak prevalence in patients who had surgery in December 2000.

Two opacification patterns of the same hydrophilic acrylic polymer: case reports and clinicopathological correlation

We report 2 intraocular lenses (IOLs) manufactured from the same hydrophilic acrylic polymer by Ioltech that developed optic opacification. In both cases, the postoperative course after implantation of the IOLs was complicated by significant inflammatory reaction with fibrin formation in the anterior chamber. Pathologic analyses of the explanted IOLs were consistent with dystrophic calcification leading to optic opacification, but the pattern was different between the 2 IOL designs. Patient-related factors might have been responsible for this complication.

Screening for drug-induced spoliation of the hydrogel optic of the AlphaCor™ artificial cornea

Clinical experience and in vitro investigations demonstrated that AlphaCor, a hydrogel keratoprosthesis, can undergo both surface spoliation and internal depositions/colourations after exposure to certain medications, alone or in combination. While the most commonly used medications have not been associated with spoliation in vivo, many medications are reportedly used due to the complex co-pathologies in many recipients, and regional variations in available medications. We screened a number of drugs used or proposed by surgeons for use in AlphaCor patients to evaluate their potential to cause visually significant optic spoliation (surface or intragel, or colour changes). Poly(2-hydroxyethyl methacrylate) discs with an identical composition to AlphaCor's optic were incubated with each medication and then with simulated aqueous humour (SAH) at 37 degrees C for 7 days. They were then examined under magnification and by histology (selected samples). Clinical feedback for the test medications was reviewed and compared with the in vitro results. A minority of the drugs caused surface spoliation (TobraDex, Prednefrin Forte, Azopt) or colour staining (including Zymar, Vigamox, Quixin) when tested alone, but SAH appeared to promote hydrogel cloudiness and surface deposits. The in vitro spoliation occurred more frequently than in vivo reports of spoliation in recipients of the same medications. This study is consistent with earlier findings in demonstrating involvement of topical medications in hydrogel spoliation, although a much lower incidence of spoliation is reported for AlphaCor in human recipients than indicated by the laboratory findings. The interactions of biological fluids and drugs require further study.

Role of silicon contamination on calcification of hydrophilic acrylic intraocular lenses

PURPOSE

To verify the presence of the element silicon on hydrophilic acrylic intraocular lenses (IOLs) explanted because of calcification.

DESIGN

Interventional case series with clinicopathological correlation.

METHODS

Twenty explanted IOLs with surface deposits (MemoryLens), and 20 with deposits mostly within their optic substance (SC60B-OUV and Aqua-Sense; 10 each) were used. After gross, microscopic, and histochemical analyses to confirm the presence of deposits, the lenses underwent scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) for elemental composition, on the external surface of MemoryLens IOLs, and on the surface and internal substance of SC60B-OUV and Aqua-Sense IOLs. The weight percentage of the element silicon was obtained at the level of deposits, and at adjacent deposit-free areas in all lenses.

RESULTS

Scanning electron microscopy (SEM) coupled with EDS confirmed that the composition of the deposits was calcium/phosphate in all cases. The element silicon was found in all 40 lenses, on all areas analyzed. The silicon weight percentage was higher at the level of the deposits. The presence of aluminum on five MemoryLens IOLs, and in most of the SC60B-OUV and Aqua-Sense lenses might be related to scattering from the aluminum mounting stubs used for surface analyses.

CONCLUSIONS

Silicone compounds have been implicated in the calcification of another hydrophilic acrylic design (Hydroview). They may also have a role in the calcification of other hydrophilic acrylic IOLs. Further investigation on the relationship between the presence of the element silicon and the silicone compounds found on calcified hydrophilic acrylic lenses is necessary.

Postoperative opacification of the peripheral optic region and haptics of a hydrophilic acrylic intraocular lens

We report the first case of opacification of the BioComFold 92S (Morcher GmbH) intraocular lens. The opacification pattern is unique, presenting mainly in the periphery of the optic and the haptics of the lens, leaving the central portion of the optic clear. The clinical course of this opacification pattern is not observed typically with other hydrophilic acrylic lens designs and requires further study.

Investigation and management of an epidemic of Hydroview intraocular lens opacification

BACKGROUND

Opacification of Hydroview posterior chamber intraocular lenses had been prescribed, but many aspects of this complication remain unknown, including its aetiology, clinical features, pathogenesis, prognosis and treatment. This paper describes an epidemic of Hydroview intraocular lens (IOL) opacification.

METHODS

Subjects in whom the Hydroview IOL was implanted were recalled for evaluation of its transparency, assessment of contrast sensitivity (CS) [VCTS (Vistech CO, Dayton, Ohio, USA)] and visual acuity (LogMAR), and analysis of medical and surgical data. The results of IOL exchange in 69 eyes of 67 patients are also presented.

RESULTS

Of 103 patients recalled, 46 (44.6%) and 3 (2.9%) exhibited opacification of the implanted IOL in one and both eyes, respectively. CS was significantly worse in the presence of an opacified IOL (P<0.050), even when Snellen acuity was unaffected. Where the viscoelastic employed during the primary cataract surgery was reliably documented, VISCOAT was used in 100% of cases (43/43), whereas Healonid had not been used in any (0/57) (P<0.0001). Following IOL exchange, visual acuity improved from a mean (+/-SD) of 0.75 (0.41) to 0.4 (0.34) LogMAR.

CONCLUSIONS

The prevalence of Hydroview IOL opacification is associated with the use of VISCOAT in the primary cataract surgery, and there is a biochemically plausible rationale to account for this. Visual acuity and contrast sensitivity are adversely affected by opacification of the Hydroview IOL, but CS to a greater extent. Exchange of opaque IOLs is a visually rewarding procedure.

Perioperative complications of intraocular lens exchange in patients with opacified Aqua-Sense lenses

PURPOSE

To evaluate the perioperative complications of intraocular lens (IOL) exchange in 25 eyes of 22 patients with opacified Aqua-Sense IOLs (Ophthalmic Innovations International).

SETTING

Department of Ophthalmology, University Hospital Aintree, Liverpool, United Kingdom.

METHODS

The study comprised 22 patients (25 eyes) who had previous phacoemulsification and implantation of Aqua-Sense single-piece hydrophilic acrylic IOLs in the capsular bag and developed severe late opacification of the IOL. All patients reported glare and deterioration in vision. The IOLs were explanted and replaced with new lenses. The perioperative complications were evaluated. The best corrected visual acuity (BCVA) before and after surgery was compared.

RESULTS

In 24 eyes, the opacification was complete, involving the optic, haptics, and substance of the IOLs. Uneventful IOL exchange and placement of a new IOL in the bag was achieved in 13 eyes (52%). Complications occurred in the remaining 12 eyes (48%). Ten eyes (40%) developed zonular dehiscence, 4 (16%) of which were managed with anterior chamber IOL implantation. One eye (4%) developed posterior capsule rupture and 1 eye (4%), posterior capsule rupture and zonular dehiscence. The cornea decompensated in 2 eyes (8%). One eye (4%) developed Pseudomonas keratitis. The mean BCVA (decimal scale) before and after IOL exchange was 0.57 +/- 0.24 and 0.60 +/- 0.28, respectively. There was no significant difference in visual acuity between before and after IOL exchange (P=.782, paired t test).

CONCLUSIONS

Explantation of Aqua-Sense IOLs was challenging because of the tight adherence of the optic and haptics to the capsule. Long-term follow-up of patients with Aqua-Sense IOLs should be maintained.

Effect of multipurpose solutions for contact lens care on the in vitro drug-induced spoliation of poly(2-hydroxyethyl methacrylate) in simulated aqueous humour

Drug-induced spoliation of hydrogels as contact lenses or as implants in the anterior eye is a frequent occurrence in clinical practice. This study explores the capacity of three commercial multipurpose solutions for contact lens care to reduce the spoliation of poly(2-hydroxyethyl methacrylate) (PHEMA) specimens exposed to a simulated aqueous humour formulation and to three topical drugs commonly administered after insertion of artificial corneas (Predsol, Optimol and Depo-Ralovera). ReNu MultiPlus (Bausch & Lomb), Complete Blink-N-Cleantrade mark Lens Drops (Allergan) and Complete Protein Remover Tablets dissolved in Complete ComfortPLUS (both from Allergan) were evaluated. All multipurpose solutions were able to dislodge passively the deposits formed on hydrogels in the simulated aqueous and in the presence of Predsol and Optimol, but none were effective against the deposits induced by Depo-Ralovera. A reduction of the calcium content in deposits caused by Predsol and Optimol was confirmed after treatment with the protein remover preparation, while the other multipurpose solutions caused the complete removal of the deposits. In experiments designed to evaluate the preventive action of the multipurpose solutions, no such effects were observed regardless of the drug involved. The prospect of using multipurpose solutions as eye drops following implantation of a hydrogel artificial cornea is a valid alternative for reducing device spoliation, however it appears to depend on the nature of the postoperative medication.

Free volume study on calcification process in an intraocular lens after cataract surgery

An opacified intraocular lens explanted from a patient in the postoperative period after phacoemulsification was investigated to find the cause of opacification. From the UV-visible and energy dispersive X-ray spectroscopy (EDS) measurements, the opacification in the present case seems to be due to calcification of the intraocular lens and not due to modification in the UV absorber material of the lens. The average free volume size of the intraocular lens both in unimplanted and explanted state were obtained from positron lifetime spectroscopy (PLS). Further, the combined FTIR and PLS results indicate that calcium gets into the free volume cavities of the intraocular lens matrix as a cationic moiety, may be in the form of Ca(++). The small decrease in glass transition temperature of the calcified lens seems to indicate the plasticizing action of calcium ions. The present results could be of some use in the design of the intraocular lens material in which calcification would be minimum.

Comparison of the Long-term Clinical Results of Hydrophilic and Hydrophobic Acrylic Intraocular Lenses

This study was performed to compare the incidence of posterior capsular opacity (PCO) and refractive errors between hydrophilic (ACR6D, Corneal) and hydrophobic (MA60BM, AcrySof) acrylic intraocular lenses (IOLs) over a 3-year follow-up after phacoemulsification surgery. The patients with AcrySof implanted in one eye and Corneal in the other eye were categorized as Group 1 (n=28), while those with one or both eyes implanted with IOLs of the same kind were categorized as Group 2 (AcrySof, n=90; Corneal, n=95). Refractive errors were evaluated at 3 months and 3 years postoperatively. The incidence of visually significant PCO was investigated 3 years postoperatively. Postoperative refractive values at 3 months were not significantly different between the two groups. However, refractive values at 3 years were significantly different between two IOLs in both groups [AcrySof -0.37+/-0.43D, Corneal -0.62+/-0.58D in Group 1 (p=0.04); AcrySof -0.38+/-0.52, Corneal -0.68+/-0.54 in Group 2 (p<0.01)]. The incidence of visually significant PCO was 14% and 32% in Group 1, and 13% and 28% in Group 2, for the AcrySof and Corneal implants, respectively. The incidence of visually significant PCO of hydrophilic acrylic IOLs was higher than that of hydrophobic acrylic IOLs in the 3-year follow-up. The postoperative 3-year refractive value of Corneal showed myopic shift.

Complications of foldable intraocular lenses requiring explantation or secondary intervention--2003 survey update

The sixth annual survey of complications associated with foldable intraocular lenses (IOLs) requiring explantation or secondary intervention was sent to members of the American Society of Cataract and Refractive Surgery and the European Society of Cataract and Refractive Surgeons. Preoperative data about visual acuity, patient signs and symptoms, and complications requiring IOL removal were evaluated. Complications were then tabulated for each of the following major foldable IOL groups: 3-piece monofocal silicone, 3-piece hydrophobic acrylic, 1-piece hydrophobic acrylic with haptics, 3-piece hydrophilic acrylic (hydrogel), 1-piece hydrophilic acrylic (hydrogel), 1-piece plate-type silicone, 3-piece multifocal silicone, and Collamer. Two hundred seventy-three surveys were returned for evaluation. Dislocation/decentration, incorrect lens power, IOL calcification, and glare/optical aberrations were the most common reasons for removing foldable IOLs. Good surgical technique, accurate IOL power measurements, and high manufacturing standards for foldable IOL materials and designs are the most important factors in avoiding complications with foldable IOLs.

Calcification postopératoire des lentilles intraoculaires acryliques hydrophiles : aspects cliniques et pathologiques

PURPOSE

The aim of this study was to evaluate the clinical aspects of ten eyes with calcified hydrophilic acrylic intraocular lenses and pathological data obtained from seven explanted lenses.

MATERIAL AND METHODS

Forty-seven eyes of 40 patients received the same implant in the first 6-month period of 2001. Ten eyes showed intraocular lens opacification detected 6-18 months after the operation: seven lenses were explanted and three were left in place because they were not causing a decrease in visual acuity or glare at light. Five of ten eyes were diabetic. The explanted lenses were examined under the light microscope and the electron microscope. The elemental analysis of the lens surfaces was made by energy dispersive spectrometry.

RESULTS

The light microscopy showed an irregular surface covered by a gray-white opacity. The electron microscopy detected multiple granulations on the front and back surfaces of the lenses including some portions of the haptics. The size and density of these granulations were smaller on the back surface. The energy dispersive spectrometry showed the presence of calcium and phosphate on both surfaces. The spikes of calcium and phosphate were smaller for the back surface of the lenses.

DISCUSSION

Calcification was predominantly seen on the surfaces that were in contact with aqueous not covered with anterior capsule. Half (5/10) of the cases were diabetic even though 18% of all patients receiving this lens were diabetic. The presence of diabetes is very common in other series. These data suggest the role of a metabolic factor influencing the milieu of the lens in this calcification process.

CONCLUSION

Calcification of the hydrophilic acrylic lenses is a relatively serious complication, but the conditions leading to its appearance and the physiopathology have not yet been fully elucidated. The surgeon should be very careful in the choice of the intraocular lens to implant, and even more so if the patient is diabetic.