Hiroyuki Matsushima

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).

Lens cytoskeleton and transparency: a model.

The function of the cytoskeleton in lens was first considered when cytoplasmic microtubules were observed in elongating fibre cells of the chick lens nearly 40 years ago.1 Since that time, tubulin, actin, vimentin and intermediate filaments have been identified and found to function in mitosis, motility and cellular morphology during lens cell differentiation.2-10 A role for the cytoskeleton in accommodation has been proposed3,8,9 and modification of the cytoskeletal proteins has been observed in several cataract models.4,11-21 Recently, a progressive increase in protein aggregation and lens opacification was found to correspond with the loss of cytoskeletal protein in the selenite model for cataract.22 In the present report a model is proposed for the role of tubulin, actin, vimentin, spectrin and the lens-specific filaments, filensin and CP49, in the establishment and maintenance of transparent lens cell structure.

Decreased visual function due to high-level light scattering in a hydrophobic acrylic intraocular lens

PurposeTo investigate the effects of light scattering from the surface of hydrophobic acrylic intraocular lenses (IOLs) on visual function.MethodsA 67-year-old man was implanted with an IOL (MA60BM) in January 1998, but became aware of decreased visual function in May 2008. Observation with a slit lamp revealed light scattering throughout the entire optic of the IOL, which was extracted and replaced. Postoperative visual function improved at 1 month. The cause of light scattering was investigated with a focus on water permeating the IOL material. To confirm the effect of light scattering on visual function, light transmission of the extracted IOL was measured in physiological saline at 33°C, and the simulated retinal image was evaluated in a model eye.ResultsObservation of the extracted IOL showed light scattering from the optic surface layer, the main cause of which was phase-separated water within the IOL material. Light transmission in the extracted IOL was 16.3% lower than that in an unused IOL in the visible range. Moreover, the simulated retinal image was hazy compared to that of the unused IOL.ConclusionSevere surface light scattering from an IOL optic may decrease visual function.

Clinical evaluation of the transparency of hydrophobic acrylic intraocular lens optics

PURPOSE: To clinically evaluate postoperative changes in the transparency of hydrophobic acrylic intraocular lenses (IOLs). SETTING: Department of Ophthalmology, Dokkyo Medical University, Tochigi, Japan. DESIGN: Case‐control study. METHODS: Eyes having phacoemulsification were randomly assigned to have implantation of 1 of 3 hydrophobic acrylic IOL models. The IOLs were photographed at 0 degree and 90 degrees 1 week, 6 months, and 1 year after implantation using a Nidek EAS‐1000 anterior chamber analyzer in slit mode. The images were used to determine the intensity of light scattering in the surface and middle regions of the IOL optic. RESULTS: The study comprised 65 eyes of 57 patients with a mean age of 72.5 years. The rate of increase in light‐scattering intensity was similar in the middle and surface regions of the Tecnis ZA9003 aspheric IOL. The increase in light‐scattering intensity in both regions of the AF‐1 VA‐60BB spherical IOL was greater than that in the aspheric IOL at all the measurement points. The intensity of light scattering was highest and tended to increase over time in both regions of the AcrySof SA60AT spherical IOL; the rate of increase in intensity was higher in the surface region than in the middle region, and the difference was significantly greater at 6 months and 1 year than at 1 week. CONCLUSION: Our results suggest that AcrySof SA60AT and AF‐1 VA‐60BB IOLs are likely to develop glistenings over time and that the former may develop whitening. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Evaluation of the Incidence of Endophthalmitis after Intravitreal Injection of Anti-Vascular Endothelial Growth Factor

Aims: To report the incidence of infectious and noninfectious endophthalmitis after intravitreal injection of anti-vascular endothelial growth factor (VEGF) from a multicenter clinical trial in Japan. Methods: A retrospective multicenter review of the data of patients who received intravitreal anti-VEGF injections between January 2007 and March 2011 was undertaken. Cases with the clinical diagnosis of endophthalmitis resulting from intravitreal injection were identified and reviewed. Results: A total of 5,236 intravitreal anti-VEGF injections (1,209 intravitreal injections of bevacizumab, 3,827 injections of ranibizumab, and 200 injections of pegaptanib sodium) had been administered. Five patients (0.095%), all of whom had received bevacizumab, were diagnosed as having endophthalmitis after the intravitreal injection. All patients visited the institutes for re-examination within 1–2 days after the injection. Among the 5 patients, 2 (0.038%) were culture positive for Streptococcus oralis and Enterococcus faecalis, respectively. The remaining 3 eyes (0.057%) developed presumed noninfectious endophthalmitis. Conclusion: Although endophthalmitis is a rare complication associated with intravitreal injection, in this series intravitreal anti-VEGF injection caused infectious or noninfectious endophthalmitis at a relatively high frequency. Further investigations are needed to consider an appropriate injection protocol for minimizing the incidence rates of endophthalmitis, and to assess the optimal treatment protocol for intravitreal injection-related endophthalmitis although it was difficult to differentiate these two entities.

Active oxygen processing for acrylic intraocular lenses to prevent posterior capsule opacification

PURPOSE: To evaluate active oxygen processing on the surface of acrylic intraocular lenses (IOLs) to prevent secondary posterior capsule opacification (PCO). SETTING: Department of Ophthalmology, Dokkyo Medical University School of Medicine, Mibu City, Tochigi, Japan. METHODS: Acrylic IOLs were prepared, and ultraviolet (UV)/ozone (UV/O3) or argon plasma was irradiated to the surface of the IOLs. Elemental analysis (electron spectroscopy for chemical analysis [ESCA]) of the IOL surfaces was performed to confirm surface modification. Changes produced by UV/O3 or argon plasma treatment were examined for fibronectin and lens epithelial cell (LEC) adhesion. To evaluate the PCO prevention by treated IOLs, 8‐week‐old albino rabbits were used. The rabbit eyes randomly had phacoemulcification and implantation of 3 different IOLs: the UV/O3‐treated IOLs, argon plasma–treated IOLs, and the control IOLs. After 2 weeks, the rabbits were killed and their globes were dissected and fixed using formaldehyde 10%. The PCO was observed using light microscopy (DX51, ORIMPUS) after hematoxylin and eosin staining. RESULTS: Comparison of IOL surface composition by ESCA showed an increase in nitrogen content and hydroxyl substitute and carboxyl substitute groups on surfaces of treated IOLs. The fibronectin adhesion and the LEC adhesion on the UV/O3‐treated and argon plasma–treated samples were increased. In the untreated group, there was statistically significant inhibition of PCO formation in the UV/O3‐treated and argon plasma–treated groups. CONCLUSION: Active oxygen processing and argon plasma irradiation on the surface of IOLs was effective in preventing secondary PCO after cataract surgery.

Preventing secondary cataract and anterior capsule contraction by modification of intraocular lenses

Advances in intraocular lens (IOL) design have led to the use of lenses with improved performance including tinting, asphericity, multifocality and accommodation. To maximize the visual performance of these IOLs, postoperative complications such as secondary cataracts and anterior capsule contraction must be prevented. Various types of secondary cataracts may occur, each associated with complex biological reactions. Different design configurations, including square-edge IOLs, have been used to prevent secondary cataracts and anterior capsule contraction, but these have not been successful in sufficiently eliminating these complications. We have found that surface modification of IOL surfaces chemically improves surface quality and is also useful in preventing secondary cataracts and anterior capsule contraction. The UV/ozone treatment that we used as a surface modification method is a simple and highly effective method with no safety issues regarding materials following treatment. The combination of square-edge design and surface modification may be able to completely eliminate these postoperative complications.

Observation of whitening by cryo-focused ion beam scanning electron microscopy.

Our results indicate that ECCE conversion can achieve good results. Converting to ECCE because of a dense nucleus or the inability to achieve a continuous curvilinear capsulorhexis seems reasonable, given that in these situations one may be able to perform an ECCE similar to the way it would have been performed had it been planned. However, if vitreous loss is present, the ECCE may result in vitreous traction. It is now generally accepted that anything that could result in vitreous traction during complicated cataract surgery should be avoided. Procedures such as cellulose sponge vitrectomy and wound sweeping with a spatula are no longer considered acceptable because of the inherent traction they produce. Delivery of the nucleus during ECCE can be achieved by “pulling”manually or by “pushing” externally or internally (using balanced salt solution or an ophthalmic viscosurgical device). In the presence of vitreous loss, all these techniques may result in vitreoretinal traction (unless fragments anterior to the posterior capsule are manually removedafter a thoroughanteriorvitrectomy). Many trainees now receive little ECCE training, making the chance of a successful conversion less likely. If ECCE is unsuccessful, subsequent vitreoretinal surgery may be hampered by an enlarged wound and a cornea that may take longer to recover than if ECCE had not been attempted. In light of the above, we currently recommend that conversion to ECCE at our unit be considered only by surgeonswho are trained in ECCE surgery and vitreous loss is neither present nor likely. We hope that future studies will elucidate the role of ECCE conversion and allow surgeons to make more informed decisions.

Photoprotective effect of yellow-tinted intraocular lenses

PurposeThe aim of this study was to experimentally investigate changes in visible light-induced photo-oxidation and to evaluate the inhibitory effect of various acrylic tinted intraocular lenses (IOLs) on photooxidation.MethodsThree types of nontinted (VA-60BB, HOYA; SA60AT, Alcon; AU-6, Menicon) and tinted (YA-60BB, HOYA; SN60AT, Alcon; AN-6, Menicon) IOLs were used. In the first experiment, we investigated oxidation related to ultraviolet rays by using a mixed solution of reduced glutathione, nicotinamide adenine dinucleotide phosphate (NADPH), and glutathione reductase. The mixed glutathione solution was irradiated for 30, 60, or 90 min with direct artificial sunlight or artificial sunlight that had been passed through various IOLs. Oxidation was detected at 340 nm. In the second experiment, human retinal pigment epithelium (RPE) cells were prepared and cultured in a 96-well dish until confluent. After light exposure for 30 min or 48 h, lactate dehydrogenase (LDH) levels of the culture supernatant were measured to assess the amount of cell damage.ResultsVisible light-induced glutathione oxidation progressed over time. Intraocular lenses inhibited photooxidation, with the inhibitory effect shown to increase when tinted IOLs were used. LDH levels in RPE cells increased as a result of exposure to visible light. There was a higher increase in LDH with nontinted than with tinted IOLs.ConclusionVisible light causes photooxidation, which damages intraocular tissue in vitro. These results suggest that tinted IOLs effectively inhibit tissue damage from visible light.

The Effects of Drug Delivery Via Hydrophilic Acrylic (Hydrogel) Intraocular Lens Systems on the Epithelial Cells in Culture

BACKGROUND AND OBJECTIVE Secondary posterior subcapsular opacification is still among the most important complications after phacoemulsification. MATERIALS AND METHODS This study was designed to assess the inhibitory effects of drugs delivered via hydrophilic acrylic (hydrogel) intraocular lens (IOL) systems in vitro. Lens epithelial cells were collected from albino rabbits. The following seven groups of hydrogel IOLs were prepared: untreated IOLs and IOLs infiltrated with diclofenac sodium, tranilast, mitomycin C, colchicines, 5-fluorouracil, and ethylenediaminetetraacetic acid. The IOLs were fixed to a Cell Culture Insert; they were then bathed and incubated in minimum essential medium containing cultured lens epithelial cells. Subsequently, a comparative analysis of the cells adhering to the collagen membrane and the lens surfaces was conducted. RESULTS Adhesion of lens epithelial cells to the lens surfaces and the collagen membrane was observed in the control group. However, only slight cellular adhesion was found on the surfaces of the IOLs and on the collagen membrane in the treated IOL groups. CONCLUSION Use of hydrogel IOLs infiltrated with drugs was associated with inhibition of posterior subcapsular opacification in vitro.