Opacification of hydrophilic acrylic intraocular lenses: a clinical and ultrastructural analysis of three explanted lenses

BACKGROUND: The purpose of our study was to report the clinical and ultrastructural results of the late opacification of three Hydroview intraocular lenses (IOLs) explanted from three patients with late postoperative visual acuity drop. PATIENTS AND METHODS: Three different patients without any systemic or ocular associated pathology presented with decreased visual acuity 12 to 24 months after uneventful phacoemulsification and Hydroview IOL implantation. The lenses were explanted and examined by photon and transmission electron microscopy (TEM), as well as through laboratory chemical analysis using bleaching with H 2 O 2, SDS-electrophoresis and silver staining for protein detection. They were cut in small pieces, fixed with osmium tetroxide 1.5 %, dehydrated through ascending grades of ethanol, and embedded in EPON 812. Ultrathin sections were stained with aqueous solutions of uranyl acetate and lead citrate, and they were examined with JEOL 2000 CX TEM. One normal IOL was also prepared in the same way and served as control. RESULTS: Control: It was transparent and no material on the surface of semithin and thin sections was detected. Cases 1 and 2: A total gray-whitish opacification of these lenses occurred. An amorphous loose material was present on semithin sections in alternation with normal areas. Evaluation with TEM revealed a pattern of network distribution within the lenses material. The latter was continuous and lightly granulated at the periphery, yet irregularly arranged in the center, more intensely stained, leaving areas of normal appearance. After bleaching, no changes in opacification were seen macroscopically. SDS-electrophoresis and silver staining did not detect proteins. Case 3: This lens had a small opacification close to the periphery. CONCLUSIONS: Late opacification of hydrophilic IOLs is not an uncommon phenomenon after uneventful cataract surgery. Although calcified deposits on the surfaces of such lenses have been reported, this is the first study that describes ultrastructural changes in the IOL material itself.     

Intralenticular opacification of hydrophilic acrylic intraocular lenses

PURPOSE: To find out the incidence of intraocular lens (IOL) optic opacification in a suspect IOL. METHODS: Retrospective review of patients' notes 3-4 years postimplant. RESULTS: In all, 56 IOLs showed signs of opacification, resulting in reduced vision out of 181 lenses traced. CONCLUSION: Certain hydrophilic acrylic IOLs like the model in question (SC60B-0UV) show opacification of the IOL, which may impair the vision of pseudophakic patients. However, not all lenses of this variety exhibit this cloudiness. Factors affecting this phenomenon are not yet completely clear but may include changes in the UV absorbant material incorporated in the lens substance itself. We report a series of patients who had received this lens and experienced loss of vision due to opacification of the IOL. In a follow-up ranging from 1 to 4 years postoperatively, a higher incidence of postoperative opacification of this lens emerges, after comparison with existing literature. IOL exchange in such patients is the only option. However, this mode of treatment should not be offered lightly as results may be guarded at best even in the face of a technically satisfactory procedure.     

Late postoperative opacification of hydrophilic acrylic intraocular lenses

BACKGROUND AND OBJECTIVE: To evaluate the incidence of postoperative opacification of hydrophilic acrylic intraocular lenses (IOLs) and discuss the surgical management. PATIENTS AND METHODS: Seventy-two eyes of 72 consecutive patients who received the same type of hydrophilic acrylic IOL (Intraocular Optical International, I.O.I., California, USA) after uneventful phacoemulsification were evaluated retrospectively. Systemic status, follow-up time, recognition time of IOL opacification, time lapse between implantation and explantation, and surgical technique during explantation were reported. RESULTS: IOL opacification was noted in 3 patients (4.1%). Time lapse between implantation and first recognition of opacification was 6.3+/-1.5 months (range: 5-8 months). Two of the patients had insulin-dependent diabetes mellitus and both were on renal dialysis for diabetic nephropathy, whereas one had no systemic disease. Opacified hydrophilic acrylic IOLs were exchanged with Acrysof IOL, and no further opacification occurred after lens exchange. CONCLUSION: Use caution on implantation of hydrophilic IOLs because late opacification is a serious complication requiring further surgery.     

Exchange technique for opacified hydrophilic acrylic intraocular lenses

PURPOSE: To report an exchange technique for opacified hydrophilic acrylic intraocular lenses (IOLs). METHODS:. Twenty patients with two different types of opacified hydrophilic acrylic IOLs underwent IOL exchange by a single surgeon. Circumferential enlargement of the pre-existing capsulorrhexis was a critical step of the procedure, and resulted in expression of the IOL with minimal traction to the capsule. Implantation of an in-the-sulcus IOL followed. Surgical technique, complications, and visual outcome are discussed. RESULTS: Time from the initial cataract operation varied from 15 to 61 months (mean 30.5), and in all cases marked fibrosis was encountered. Eighteen patients had uncomplicated IOL exchange. Posterior capsule rupture occurred in two cases. Vision improved in 16 cases, remained unchanged in 3 cases, and deteriorated in 1 case. CONCLUSIONS: IOL exchange of opacified hydrophilic acrylic IOLs is a particularly challenging procedure due to extensive fibrosis. Circumferential enlargement of the pre-existing capsulorrhexis significantly facilitates the mobilization of the IOL from its fibrous pocket, with the use of minimal forces. Thus, the risk of zonular dehiscence or posterior capsule rupture is minimized.     

Opacification of hydrophilic MemoryLens U940A intraocular lenses: analysis of 2 explanted lenses

PURPOSE: To determine the rate of opacification of hydrophilic MemoryLens U940A intraocular lenses (IOLs) (Mentor Ophthalmics, Inc.) in the given cohort and perform a histopathological and spectrophotometer analysis of 2 explanted opacified IOLs. SETTING: Ophthalmology Department, Faculty Hospital, Nitra, Slovakia. METHOD: This retrospective study comprised 182 patients (205 eyes) who had implantation of a MemoryLens U940A IOL from June 1997 to June 2000. The patients were examined using a slitlamp to detect the presence of IOL opacification. In 4 cases, the lenses were explanted because of significant opacification and patient-reported problems; 2 lenses were provided for further analysis. One unused reference MemoryLens U940A IOL was also evaluated. All IOL were stained with von Kossa to determine the presence of calcium in the opacification. To confirm the components presence of an ultraviolet (UV) absorber, the IOLs were examined with an Avatar 330 Fourier transfer infrared (IR) spectroscope and a UV visible spectrophotometer (Philips). The IR spectrums for the IOL were identified using an IR spectrum atlas. The opacified IOLs, reference IOL, and the IOL packaging were further examined to determine the presence of silicone. RESULTS: Various amounts of opacification were found on the MemoryLens U940A IOL in 30 eyes (30 patients) (14.63%). Two explanted IOLs were positive for von Kossa staining, proving the presence of calcium deposits; the reference lens staining was negative. Spectrophotometry showed that the reference IOL and opacified IOLs were of the same polymer. The presence of the UV absorber on the benzophenone base was seen in the reference lens but not the opacified IOLs. In contrast, an increased concentration of low-molecular-weight components generated during the degradation of the polymer was present in the opacified lenses. The white cover pf the IOL is of polydimethyl siloxane, a silicone rubber. However, no silicone rubber was present in any examined lens, perhaps because the IOLs were in contact with alcohol during the histopathologic examination. CONCLUSIONS: The results indicate opacification of the hydrophilic MemoryLens U940A was caused by premature consumption of the UV absorber in the polymer component of the IOLs optic, with a subsequent degradation of the polymer. Whether silicone from the white cover led to the IOL opacification, as reported with other types of hydrophilic IOLs, could not be confirmed.     

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.     

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

PURPOSE: To identify the nature and to investigate the biochemical mechanisms leading to late opacification of implanted hydrophilic acrylic intraocular lenses (IOLs). DESIGN: Retrospective laboratory investigation. METHODS: setting: Department of Ophthalmology, Medical School, Department of Chemical Engineering, Laboratory of Inorganic and Analytical Chemistry, University of Patras and FORTH-ICEHT, Greece. study population: Thirty IOLs were explanted one to 12 years postimplantation attributable to gradual opacification of the lens material. observation procedures: Materials analysis was done using scanning electron microscopy (SEM) equipped with a microanalysis probe (EDS), confocal microscopy, x-ray diffraction (XRD), and Fourier transform infrared (FTIR) for the identification of the substances involved in the opacified lenses. RESULTS: SEM investigation showed plate-like as well as prismatic nanoparticle deposits of calcium phosphate crystallites on the surface and in the interior of opacified IOLs. The plate-like deposits exhibited morphology and particle size typical for octacalcium phosphate (OCP), while the respective characteristics of the prismatic nanocrystals were typical of hydroxyapatite (HAP). EDS analysis confirmed the chemical composition of the deposits. Aqueous humor analysis showed that the humor is supersaturated with respect to both OCP and HAP, favoring the formation of the thermodynamically more stable HAP, while the formation and kinetic stabilization of other transient phases is also very likely. In vitro experiments using polyacrylic materials confirmed the clinical findings. CONCLUSIONS: Hydrophilic acrylic IOLs' opacification may be attributed to the deposition of calcium phosphate crystallites. HAP is the predominant crystalline phase of these crystallites. Surface hydroxyl groups of the polyacrylic materials facilitate surface nucleation and growth.     

Progressive opacification of hydrophilic acrylic intraocular lenses in diabetic patients

Four patients with diabetes mellitus had cataract extraction with implantation of a hydrophilic acrylic intraocular lens (IOL) (ACRL-C160, Ophthalmed). The IOLs showed progressive and generalized opacification 10 to 20 months after implantation, decreasing visual acuity. All 4 IOLs were removed. By light microscopic examination, the IOL surfaces were wrinkled and encrusted with microspheres. Electron microscopy revealed the material to be crystalline in nature. Energy dispersive x-ray spectrum analysis showed that the deposits were mainly composed of calcium and phosphate.     

Biological compatibility of polymethyl methacrylate, hydrophilic acrylic and hydrophobic acrylic intraocular lenses

PURPOSE: Extensive clinical investigations of the biocompatibility of different intraocular lenses (IOLs) have been made in an effort to optimize the outcome of modern cataract surgery. The aim of this study was to add animal eye experimental implantation data regarding cellular reaction on the anterior surface of IOLs. METHODS: Thirteen adult albino rabbits had phacoemulsification/aspiration of the crystalline lens followed by implantation of a posterior chamber IOL in each eye. Three types of IOLs were studied: Hydroview (Bausch and Lomb; n = 7), Acrysof (Alcon, USA; n = 7), and polymethyl methacrylate (PMMA; HOYA, Japan; n = 7). The animals were killed by intravenous pentobarbital 1, 4, or 8 weeks later. The IOLs were explanted and stained with hematoxylin and eosin, and observed under a light microscope. The shape of mouse ascites-induced macrophages on the anterior surface of the three different IOL types (Hydroview, PMMA, and Acrysof) was studied after 24 h of oven culture. RESULTS: Hydrophilic acrylic IOLs showed the highest affinity for lens epithelial cell (LEC) outgrowth, and the lowest and slowest maturation rate reaction of macrophages. PMMA IOLs showed the lowest affinity for LEC outgrowth, and the highest reaction of macrophages. Hydrophobic acrylic IOLs showed intermediate results both regarding LECs and macrophages. CONCLUSIONS: Results suggest that IOL biomaterial properties are the key factor that influences the quantity of monocytes/macrophages as well as the process of their maturation/senescence. LEC outgrowth is influenced both by the biomaterial of IOLs and by the monocyte/macrophage reaction.     

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.     

Calcification of hydrophilic acrylic intraocular lenses: clinical and pathological aspects

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.