Effect of heparin surface modification in reducing silicone oil adherence to various intraocular lenses.

PURPOSE: To evaluate surface properties of various intraocular lenses (IOLs), including a newly fabricated heparin-surface-modified (HSM) silicone IOL, with special reference to their efficiency in reducing potential silicone oil adherence to the IOL optics. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Five groups of rigid and foldable IOLs were analyzed in an in vitro test for the percentage of silicone oil adherence: a single-piece foldable hydrophilic-acrylic IOL (n = 9); a single-piece rigid poly(methyl methacrylate) (PMMA) IOL with HSM coating of the lens optic (n = 9); a 3-piece foldable silicone optic IOL with HSM coating of the optic (n = 10); a single-piece standard rigid PMMA IOL (n = 7); and a standard 3-piece foldable silicone optic IOL (n = 9). After the IOLs were immersed in water and then in silicone oil, gross photographs taken. Image analysis was performed to evaluate the percentage of silicone oil coverage of the anterior and posterior surfaces of each IOL optic. RESULTS: The mean silicone oil coverage of the hydrophilic-acrylic IOLs was 5.6% +/- 2.5% (SD); of the HSM PMMA IOLs, 6.2% +/- 4.3%; of the HSM silicone optic IOLs, 6.7% +/- 3.2%; and of the standard PMMA IOLs, 20.3% +/- 13.3%. The mean silicone oil coverage was greatest on the standard silicone optic IOLs, 98.2% +/- 3.1%. CONCLUSIONS: Intraocular lenses with a hydrophilic optic have less tendency toward adherence to silicone oil than more hydrophobic designs. A foldable silicone IOL with heparin surface modification can significantly reduce potential silicone oil adherence, comparable to the level achievable with the rigid HSM PMMA designs. Two new foldable IOL styles, the HSM silicone IOL and IOLs in the general class of hydrophilic-acrylic, were highly efficacious in reducing silicone oil adherence. There is now a real choice of foldable lenses for patients with actual or potential vitreoretinal diseases.     

Interaction of intraocular lenses with various concentrations of silicone oil: an experimental study

The aim of this study was to evaluate the interaction between various widely used intraocular lenses (IOLs) and silicone oils of different viscosities. Four groups of IOLs, including monoblock foldable hydrophilic acrylic IOLs (Morcher, type 92s); monoblock hydrophobic acrylic IOLs (Acrysof-SA60AT, Alcon); single-piece rigid polymethylmethacrylate (PMMA) IOLs (Intraocular Optical International-IOI-65130) and a three-piece foldable silicone optic IOL (CeeOn Edge 911A, Pharmacia UpJohn) were analyzed in vitro to determine the percentage adherence 1,000-centistoke, 1,300-centistoke or 5,000-centistokes silicone oil on the IOL optic. For each IOL type, there was no statistically significant difference in the mean silicone oil coverage (MSC) of the IOL optics for the different viscosities of silicone oil. Silicone IOLs had the highest MSC percentage (79.9%) whereas hydrophilic acrylic IOLs were the least silicone-covered IOLs (7.8%) compared to the other IOL types tested in this study. It is not the concentration of silicone oil that affects silicone oil coverage. When performing small-incision cataract surgery in patients who may require silicone oil injection, foldable hydrophilic acrylic or hydrophobic acrylic lenses should be preferred over standard foldable silicone lenses.     

Adherence of triamcinolone acetonide to various intraocular lens materials

PURPOSE: To determine the adherence of triamcinolone acetonide to various intraocular lens (IOL) materials. SETTING: Department of Ophthalmology, Dokuz Eylül University, Izmir, Turkey. METHODS: Four IOLs of 4 materials (single-piece poly(methyl methacrylate) [PMMA], 3-piece foldable silicone, 3-piece hydrophobic acrylic, and single-piece hydrophilic acrylic) were first immersed in triamcinolone acetonide (40 mg/mL) for 15 minutes and then bathed in a balanced salt solution for another 15 minutes. Afterward, each lens optic was examined under light microscopy and digital images were obtained with a digital color video camera. The percentage of optic area covered with triamcinolone acetonide was determined by image analysis. RESULTS: Mean triamcinolone coverage was 7.62% +/- 4.06% (SD) for PMMA IOLs (range 1.97% to 11.43%), 9.09% +/- 4.60% for silicone IOLs (range 4.70% to 15.32%), 8.75 +/- 7.20% for hydrophobic acrylic IOLs (range 1.31% to 16.86%), and 23.16 +/- 8.53% for hydrophilic acrylic IOLs (range 15.02% to 35.12%). Adherence of triamcinolone acetonide to hydrophilic acrylic lenses was statistically significant when compared with other IOL materials. CONCLUSION: Intraoperative triamcinolone injection may obscure visualization intraoperatively and postoperatively, especially in eyes with hydrophilic acrylic lenses, because triamcinolone acetonide seems to have a tendency to adhere to hydrophilic acrylic lenses in vitro.     

Interaction with intraocular lens materials: Does heavy silicone oil act like silicone oil?

PURPOSE: To determine the interaction of heavy silicone oil with various intraocular lens (IOL) materials and whether heavy silicone oil covers the silicone IOL optic as silicone oil does. SETTING: Department of Ophthalmology, Dokuz Eylul University, Izmir, Turkey. METHODS: The study group comprised 5 poly(methyl methacrylate) (PMMA) IOLs, 4 foldable silicone IOLs, 5 foldable hydrophilic acrylic IOLs, and 5 foldable hydrophobic acrylic IOLs. Each IOL was bathed in balanced salt solution (BSS) for 10 minutes and then placed in heavy silicone oil dyed with Sudan Black for another 10 minutes. Afterward, each IOL was reimmersed in BSS for 5 minutes and examined under the light microscope. Digital images were analyzed to determine the optic area covered with heavy silicone oil. RESULTS: The mean heavy silicone oil coverage was 7.05% +/- 7.88% (SD) (range 1.13% to 20.54%) on PMMA IOLs, 100% on silicone IOLs, 12.17% +/- 11.43% (range 1.25% to 31.52%) on hydrophobic acrylic IOLs, and 34.64% +/- 13.28% (range 12.57% to 44.42%) on hydrophilic acrylic IOLs. Heavy silicone oil coverage of silicone IOLs was statistically significantly greater than the coverage of other IOL materials. CONCLUSION: Heavy silicone oil acted the same as silicone oil and covered the entire surface of silicone IOLs.     

Comparison of glistenings in intraocular lenses with three different materials: 12‐year follow‐up

Purpose: To compare the degree of lens glistenings associated with three intraocular lenses (IOLs) of different materials and examine the relationship between the dioptric power of the optics and lens glistenings in a long‐term study. Setting: St. Erik Eye Hospital, Stockholm, Sweden. Methods: Forty‐six eyes of 46 patients underwent standard phacoemulsification and implantation with a heparin‐surface‐modified (HSM) polymethylmethacrylate (PMMA) IOL, a silicone IOL or a hydrophobic acrylic IOL. Evaluations of the patients and the glistenings were conducted 11.3–13.4 years postoperatively. The glistenings were examined using Scheimpflug imaging and subsequently analysed using an image analysis program. Results: The median follow‐up time was 12.2 years (range, 11.3–13.4). The hydrophobic acrylic IOL had significantly more lens glistenings than the silicone (p = 0.003) and the PMMA (p = 0.000) IOLs. The silicone IOL had significantly more lens glistenings than the PMMA lens (p = 0.048). The IOL power did not affect the degree of lens glistenings in the hydrophobic acrylic IOL group (p = 0.64). The other groups had too little lens glistenings to evaluate the relationship. Conclusion: In this long‐term follow‐up study, the hydrophobic acrylic IOL had a significantly higher degree of lens glistenings compared to the silicone and PMMA IOLs. The PMMA IOL had almost no lens glistenings. The IOL dioptric power was not significantly correlated with the degree of lens glistenings associated with the hydrophobic acrylic IOL.     

Cell adhesion to acrylic intraocular lens associated with lens surface properties

PURPOSE: To examine the number cells adhering to acrylic intraocular lenses (IOLs) having different degrees of surface roughness and acrylic IOLs having different contact angles. SETTING: Department of Ophthalmology, Tokyo Medical University Hospital, Tokyo, Japan. METHODS: In this study, VA-60 CB acrylic IOLs were used. After different durations of polishing of the optics, the roughness values of the lenses were set at 10.0 nm, 2.5 nm, and 0.7 nm. Intraocular lenses were also chemically coated to achieve angles of contact of 100 degrees and 57.5 degrees, with untreated IOLs having a 93.5-degree angle of contact. Intraocular lenses were cultured for 96 hours in 1 x 10(7) spleen cells/mL of developed experimental autoimmune uveoretinitis, and the number of cells adhering to the IOLs was counted. RESULTS: Fewer cells adhered to the optics of IOLs with lower roughness values, and fewer cells adhered to the IOL surface with increased contact angles. CONCLUSION: Hydrophobic optics with small roughness values of acrylic IOLs may reduce the number of adherent cells and escaped the unexpected inflammatory cell reaction associated with intraocular inflammation in the eye.     

Inhibition of lens epithelial cell migration by an acrylic intraocular lens in vitro

We developed a new in vitro system to evaluate the effect of intraocular lenses (IOLs) on the migration of lens epithelial cells (LECs) and determined how acrylic and other IOLs influence LEC migration using this model. In an in vitro system, porcine LECs were cultured in a cell culture chamber insert, containing a collagen membrane, for 10 days with no IOL or with various types of IOLs. Migration of LECs beneath each IOL optic was observed with an inverted-phase microscope. The cell-free areas under the IOL optic, where the LECs had not migrated, were measured. Without IOL, LECs completely covered the collagen membrane within 5 days after plating (5.0 +/- 0.0 days). Complete coverage was slowed by a silicone IOL (6.7 +/- 1.2 days, p = 0.0305). LECs cultured with acrylic or with round- or sharp-edged polymethylmethacrylate (PMMA) IOLs did not completely cover the area. Ten days after initiating cultures, the cell-free areas under IOLs with sharp edges (acrylic, 41.1 +/- 8.0%; sharp-edged PMMA, 60.9 +/- 39.0%) were significantly larger than under IOLs with round edges (silicone, 0.0 +/- 0.0%; round-edged PMMA, 1.5 +/- 1.2%). A sharp edge may act as a barrier to LEC migration. Moreover, LEC migration under the acrylic IOL slowed after the LECs had crossed the barrier of the optic edge, perhaps due to acrylic adhesive properties. Only a few LECs reached the collagen membrane beneath the central 3 mm of the acrylic IOL. This new in vitro model was useful in evaluating the effect of various IOLs on LEC migration. Acrylic IOLs inhibited LEC migration by not only a sharp edge but also other factors, such as adhesive properties.     

Material properties of various intraocular lenses in an experimental study

INTRODUCTION: With the recent introduction of small-incision cataract surgery, requirements for intraocular lens (IOL) flexibility, strength and hydrophilicity have rapidly evolved. The IOL surface, however, remains a critical factor influencing uveal biocompatibility. PURPOSE: To objectively quantify factors of material properties of various IOLs using contact angle measurements, differential scanning calorimetry, dynamic-mechanical measurements and scanning electron microscopy. MATERIAL AND METHODS: In our study, 17 currently available IOLs were investigated using contact angle measurements to assess hydrophilicity and biocompatibility, as well as differential scanning calorimetry for the estimation of glass transition temperature. Mechanical capacity and flexibility were investigated using dynamic-mechanical measurements. Additional analysis of the IOL surface was performed using scanning electron microscopy. RESULTS: The contact angle measurements of the studied IOLs revealed similar values within each group. The silicone IOLs had values between 106 and 119 degrees. The PMMA IOLs were found to have a narrower range of values, between 73.2 and 75.5 degrees. Lenses made of hydrogel had values between 59.2 and 69.1 degrees. The heparin-modified surface showed the lowest contact angle of 56.5 degrees. The glass transition temperature was determined by dynamic differential scanning calorimetry. The resulting values were between 118.8 and 113.5 degrees C for PMMA IOLs, 15.5 and 14.0 degrees C for acrylic IOLs, and -91.7 and -119.6 degrees C for silicone IOLs. The dynamic-mechanical measurements revealed that PMMA lenses manifested characteristics similar to glass, whereas silicone lenses had characteristics similar to rubber. Acrylic lenses were between rubber and glass. Scanning electron microscopy revealed smooth dispersion of fibrin on hydrophobic IOLs and a relative lack of fibrin adhesion on hydrophilic materials. CONCLUSION: These results demonstrate that material properties of various IOL materials are consistent within classes of IOL materials. This suggests that the intraoperative and postoperative behavior of an IOL is predictable and related to its composition, thus allowing surgeons to choose IOLs more appropriate for different surgical situations and individual patient characteristics.     

Differential responses of human lens epithelial cells to intraocular lenses in vitro: hydrophobic acrylic versus PMMA or silicone discs

Background The purpose of this study was to determine the influence of different materials of intraocular lenses (IOLs) on human lens epithelial cell behavior, including adhesion, migration, proliferation, apoptosis, and epithelial-mesenchymal transdifferentiation (EMT) in vitro. Methods Human lens epithelial cells (SRA 01/04) were grown on hydrophobic acrylic (Acrysof), polymethylmethacrylate (PMMA), and silicone IOLs. Cellular adhesion, migration, proliferation, and apoptotic assays were performed to assess cell behavior. The expression of EMT markers (fibronectin and type I collagen) produced by cells on IOLs was determined by immunoblotting and immunocytochemistry. Results Human lens epithelial cells exhibited preferred adhesion and reduced apoptosis when cultured on acrylic IOLs, in comparison to PMMA and silicone IOLs. Cells grown on acrylic lenses formed a confluent epithelial monolayer. Migration of lens epithelial cells under the acrylic lens was substantially blocked in an in vitro assay. In contrast, cells grown on PMMA and silicone lenses displayed a spindle-shaped, myofibroblast-like morphology, increased apoptosis, reduced adhesion, and enhanced production of EMT proteins such as fibronectin and type I collagen. The migration of lens epithelial cells under PMMA and silicone IOLs was substantial in the in vitro assay. Conclusion This report demonstrates that hydrophobic acrylic lenses are more capsular biocompatible than PMMA and silicone lenses. The in vitro assays are reliable measurements for evaluating the responses of human lens epithelial cells to different IOL materials, and could advance our understanding of the preferential capsular opacification conferred by different IOL materials.     

Adhesion of lens capsule to intraocular lenses of polymethylmethacrylate, silicone, and acrylic foldable materials: an experimental study

AIMS—To investigate the adhesion characteristics of several intraocular lenses (IOLs) to the simulated and rabbit lens capsule.
METHODS—Adhesive force to bovine collagen sheets was measured in water with polymethylmethacrylate (PMMA), three piece silicone, and acrylic foldable IOLs. In rabbit eyes, phacoemulsification and IOL implantation were performed. Three weeks later, adhesion between the anterior/posterior capsules and IOL optic was tested, and the capsule was examined histologically.
RESULTS—The mean adhesive force to the collagen sheet was 1697 (SD 286) mg for acrylic foldable, 583 (49) mg for PMMA, and 0 mg for silicone IOLs (p=0.0003, Kruskal-Wallis test). Scores (0-5) of adhesion between rabbit anterior capsule and IOL optic were 4.50 (0.55) for acrylic foldable, 3.20 (0.84) for PMMA, and 0.40 (0.55) for silicone IOLs (p=0.004). Scores between rabbit posterior capsule and IOL optic displayed a similar tendency; 4.50 (0.84) for acrylic foldable, 3.00 (1.00) for PMMA, and 0.40 (0.55) for silicone IOLs (p=0.021). Histological observation indicated that the edge of IOL optic suppressed the migration of lens epithelial cells towards the centre of the posterior capsule. This inhibitory effect was most pronounced with acrylic foldable IOL and least with silicone IOL.
CONCLUSIONS—The acrylic foldable IOL adhered to the lens capsule more than the PMMA IOL, and the silicone IOL showed no adhesiveness. These differences seem to play a role in preventing lens epithelial cells from migrating and forming posterior capsule opacification.

Keywords: intraocular lens; lens capsule; posterior capsule opacification; adhesion     

Elapsed time for capsular apposition to intraocular lens after cataract surgery

OBJECTIVE: To examine when the anterior and posterior lens capsule completely become apposed to optics of silicone and acrylic intraocular lenses (IOLs) implanted after cataract surgery and to determine whether the different IOL materials influence the timing of completion of capsular contact. DESIGN: Randomized controlled clinical trial. PARTICIPANTS: Seventy eyes of 70 patients who were scheduled to undergo cataract surgery were randomly assigned to two groups using random number tables based on the type of IOL implanted: silicone or acrylic. Thirty-two patients in each group completed the follow-up. INTERVENTION: All eyes underwent phacoemulsification surgery with implantation of either a silicone or acrylic IOL. All IOLs were accurately placed into the capsular bag. MAIN OUTCOME MEASURES: Contact of the anterior and posterior lens capsule with the IOL optic surface was evaluated using the Scheimpflug videophotography system at 3, 5, 7, 9, 11, 14, 21, and 28 days after surgery. The postoperative day at which each capsule was completely apposed to the IOL optic was determined. In addition, anterior chamber depth was also measured. RESULTS: The anterior capsule was in contact with the IOL optic on the same day or earlier than the posterior capsule in all patients. Complete apposition of the IOL was observed significantly earlier with silicone IOLs than with acrylic IOLs with both the anterior capsule (6.2 versus 3.6 postoperative days; P < 0.0001) and the posterior capsule (11.1 versus 7.4 postoperative days; P = 0.0339). No significant change in mean anterior chamber depth was observed with the silicone IOL, whereas there was significant anterior shift after implantation of the acrylic IOL. CONCLUSIONS: Capsular contact with the IOL optic is completed within approximately 8 days after cataract surgery with silicone IOLs and 11 days with acrylic IOLs. Complete apposition to both the anterior and posterior capsule was significantly earlier with silicone IOLs than with acrylic IOLs.     

Chemoattraction of inflammatory cells by various intraocular lens materials

PURPOSE: To compare the chemotactic activity induced by polymethyl methacrylate (PMMA), acrylic, and silicone intraocular lens (IOL) materials, regardless of the surgical and host factors. METHODS: The chemotactic effect of five different IOLs was studied using a modified multi-well Boyden chamber. Two different non-coated PMMA IOLs, a heparin-coated PMMA IOL, an acrylic IOL, and a silicone IOL were assessed. Each mean migration distance of the IOLs was compared with the others using Student's t test. RESULTS: All IOLs induced some amount of leukocyte chemotaxis. There was no statistically significant difference between the chemotactic activity of PMMA IOLs. However, chemotactic activity was significantly higher in acrylic (p<0.05) and silicone (p<0.05) IOLs compared to one of the PMMA lenses. CONCLUSIONS: This limited study has proven that chemotaxis assay is a useful tool to assess the biocompatibility of IOLs. The IOL material itself might attract inflammatory cells to its surface in the absence of surgical and host factors. As PMMA IOLs do not cause an increase in inflammatory reaction, they may be considered safe to use. Further improvement in chemical composition and surface characteristics of IOLs should reduce the inflammatory reaction and increase the biocompatibility and safety of IOLs.     

Incision sizes with 5.5 mm total optic, 3-piece foldable intraocular lenses

PURPOSE: To determine incision sizes for 5.5 mm total optic, foldable intraocular lenses (IOLs) made of silicone or hydrophobic acrylic. SETTING: Johann Wolfgang Goethe-University, Department of Ophthalmology, Frankfurt am Main, Germany. METHODS: In a prospective randomized clinical study including 40 cataract procedures with a temporal limbal tunnel approach, incision sizes for 5.5 mm optic, 3-piece foldable IOLs were measured before and after phacoemulsification and before and after IOL implantation using calipers. Three 5.5 mm optic, 3-piece foldable IOLs were used: 2 silicone (Pharmacia CeeOn 912, Allergan SI-55NB) and 1 hydrophobic acrylic (Alcon AcrySof MA30BA). Ten lenses of each model were implanted with a forceps, and 10 SI-55NB IOLs were implanted with the AMO Unfolder injector. Measurements of the tunnel incisions at various times were statistically evaluated using an analysis of variance and the Tukey-Kramer multiple comparison test. RESULTS: Mean tunnel width before and after implantation, respectively, was 3.32 mm+/- 0.06 (SD) and 3.42+/- 0.06 mm for the CeeOn 912 using a Nichamin implantation forceps, 3.28+/- 0.09 mm and 3.42+/- 0.09 mm for the AcrySof MA30BA using a Buratto implantation forceps, 3.00+/- 0.07 mm and 3.10+/- 0.05 mm for the SI-55NB using a Fine Universal II Folder, and 2.66+/- 0.08 mm and 2.81+/- 0.11 mm for the SI-55NB using the AMO Unfolder. Incision sizes before and after implantation were statistically different between 2 IOLs (CeeOn 912 and MA30BA) and the SI-55NB groups. Implantation of the SI-55NB with the Unfolder was associated with significantly smaller incision sizes before and after implantation than implantation with the Fine folder. CONCLUSIONS: Incisions sizes of 2.8 to 3.4 mm were associated with 5.5 mm total optic, 3-piece foldable IOLs. The Allergan SI-55NB high-refractive-index silicone IOL implanted with the AMO Unfolder system provided the smallest postimplantation incision; however, the refractive optic of this IOL is 5.0 mm versus 5.5 mm for of the CeeOn 912 and AcrySof MA30BA.     

Scanning electron microscopic study of 12 lenses of two types of soft acrylic intraocular lenses]

BACKGROUND: Evaluation of the surface properties of two models of one-piece foldable acrylic intraocular lenses (IOLs) before and after folding and passing the IOLs through an injector. METHODS: We studied two foldable IOL models made of a polymethacrylate/2-hydroxyethylmethacrylate copolymer: EasAcryl 1(R) (Chiron) and Raysoft(R) 547H (Rayner). Twelve IOLs of each design with different diopters were examined. Light and scanning electron microscopy were performed before and after IOL folding and passing the IOLs through a Micra G103 injector (Chiron Adatomed) and an IC-2BU inserter cartridge (Chiron Microsert II). RESULTS: All IOLs presented a homogeneous surface and smoothly finished edges of haptics and optics. The inner edges of all IOL haptics and the optic edges of some IOLs had ridges at high magnifications. No IOL demonstrated any folding defects of the optic such as a folding line or scratches. Three of 16 folded IOLs showed defects or cracking of the IOL haptics due to incomplete placement in the inserter cartridge. CONCLUSIONS: The two models of soft acrylic intraocular lenses showed excellent surface quality. After folding and injection process no alteration of the optics was detected in any of the IOLs. However, the IOLs need careful placement in the inserter cartridge to avoid haptic damage.     

Morphological appearance and size of contact zones of piggyback intraocular lenses

PURPOSE: To characterize the morphology, size, and change in size of the contact zone of piggyback intraocular lenses (IOLs) of different materials and optic designs. SETTING: Department of Ophthalmology, Vienna General Hospital, Vienna, Austria. METHODS: In a prospective study, 9 eyes of 7 patients received piggyback IOLs of the following materials: poly(methyl methacrylate) (PMMA), acrylic, hydrogel, and silicone. The contact zone between the anterior and posterior IOLs was photodocumented from 1 day to 1 year after surgery using specular microscopy. The contact zone area was measured. RESULTS: A contact zone was present with all IOL materials studied. The area of contact, however, differed significantly. With PMMA IOLs, the contact zone was small and surrounded by Newton rings, indicating the tiny gap between the IOLs. With IOLs of soft material, such as silicone and hydrogel, it was larger than with PMMA IOLs and had a slightly irregular shape. With foldable acrylic IOLs, it was regular, round, and slightly larger than with the soft materials. The contact area enlarged primarily during the first 3 months after surgery. After 1 year, 2 eyes with acrylic piggyback IOLs had a membrane formation around the contact zone and 2 eyes developed Elschnig pearls between the IOLs. CONCLUSION: In piggyback IOL eyes, the shape and size of the contact zone were strongly dependent on the IOL material and optic design. Contact area enlargement seemed to be induced by capsule shrinkage. Fibrous membrane formation around the contact zone and Elschnig pearl formation between the piggyback IOLs were long-term complications of this technique.     

The experimental study of Nd: YAG laser injuring effects on intraocular lenses made by different materials

OBJECTIVE: To inquire the injuring effects of the Q-switched neodymium: yttrium aluminum garnet (Nd : YAG) laser on silicone, hydrogel (HEMA), acrylic, lathe cutting and cast molding polymethylmethacrylate (PMMA) intraocular lenses (IOLs). METHODS: The Nd : YAG of different energy was focused on the posterior surface of the IOL optic portion and shot in air and BSS separately. The percentages of IOL injuries were calculated, and the morphology of the IOL injuries was observed with a scanning electron microscope. RESULTS: Percentages of IOL injury: When the same energy of Nd : YAG laser was used, the injuring effects on the same kind of IOLs in air and in BSS were similar, while the laser energies of 0.5 mJ and 1.0 mJ were used, the injuring effects on different kinds of IOLs were significantly different, and when the energy of the laser was more than 1.5 mJ, the injuring effects were almost the same. Under different conditions, the morphology of the injury on different kinds of IOLs was different. CONCLUSIONS: (1) The sequence of resisting ability against Nd : YAG laser injury of different kinds of IOLs from strong to weak is: The lathe cutting PMMA IOL > acrylic IOL > cast molding PMMA IOL > HEMA IOL and silicone IOL. (2) The injuring effect of high energy Nd : YAG laser on rigid IOL is more severe than that on the soft IOL. (3) The size of IOL injuries is increased with the elevation of energy level of Nd : YAG laser.     

Ultrasound biomicroscopy characterization of acrylic, silicone, and polymethyl methacrylate lenses in vitro

Background: This study aims to characterize the reflective properties of some commonly used intraocular lenses (IOLs) in vitro, with a particular focus on lens haptics.Methods: Six different types of IOLs, representative of silicone, acrylic, and polymethyl methacrylate (PMMA), single, multipiece, and multifocal were imaged using high-resolution ultrasound biomicroscopy (UBM).Results: Reflectivity patterns were distinct to the material that was being imaged irrespective of whether the part being imaged was the haptic or optic. Acrylic haptics demonstrated a single “tram-track” reduplication echo, whereas PMMA haptics showed multiple reverberation echoes off the posterior surface. The optics of various PMMA and acrylic lenses demonstrated a reflectivity pattern similar to the respective haptics made of the same material. Silicone optics displayed clear delineation with no reverberation. Both acrylic and silicone material was relatively less reflective when compared with PMMA.Interpretation: With UBM imaging, the haptics of acrylic and PMMA IOLs demonstrate unique reflective patterns, depending on the material being studied. Prior knowledge of what the lens haptics and optics look like in vitro provides information that may assist in identifying and localizing misplaced intraocular lenses in vivo.     

Tilt and decentration of three-piece foldable high-refractive silicone and hydrophobic acrylic intraocular lenses with 6-mm optics in an intraindividual comparison

PURPOSE: Intraindividual comparison of tilt and decentration of three-piece foldable intraocular lenses (IOLs) with 6-mm optics and different edge design and material. DESIGN: Prospective randomized study. METHODS: Twenty-five patients with senile cataract (group I) received a foldable silicone, sharp optic edge IOL in one eye and a silicone, rounded optic edge IOL in the other eye. Group II (n = 28) received the foldable silicone, sharp optic edge IOL in one eye and an acrylate, sharp optic edge IOL in the other eye. Scheimpflug photography was performed after the procedure with an anterior eye segment analysis system. Tilt and decentration of the IOL optic were measured 1 week, 6 months, and 12 months after the procedure. RESULTS: In group I, the foldable silicone, sharp optic edge IOL showed a mean optic tilt of 3.03 +/- 1.79 degrees and an optic decentration of 0.24 +/- 0.13 mm; the silicone, rounded optic edge IOL showed a tilt of 3.26 +/- 1.69 degrees and a decentration of 0.23 +/- 0.13 mm. In group II, the foldable silicone, sharp optic edge IOL showed an average tilt of 2.34 +/- 1.81 degrees and a decentration of 0.29 +/- 0.21 mm after 12 months; the acrylate, sharp optic edge IOL had a tilt of 2.32 +/- 1.41 degrees and a decentration of 0.24 +/- 0.10 mm. There were no significant differences in either group. CONCLUSION: The examined IOLs showed a stable position regarding tilt and decentration in the first 12 postoperative months, independent of material and edge design. Slight deviations from the optical axis might affect the outcome in aspheric or multifocal IOLs.     

Chemoattraction of Inflammatory Cells by Various Intraocular Lens Materials

Purpose: To compare the chemotactic activity induced by polymethyl methacrylate (PMMA), acrylic, and silicone intraocular lens (IOL) materials, regardless of the surgical and host factors. Methods: The chemotactic effect of five different IOLs was studied using a modified multi-well Boyden chamber. Two different non-coated PMMA IOLs, a heparin-coated PMMA IOL, an acrylic IOL, and a silicone IOL were assessed. Each mean migration distance of the IOLs was compared with the others using Student's t test. Results: All IOLs induced some amount of leukocyte chemotaxis. There was no statistically significant difference between the chemotactic activity of PMMA IOLs. However, chemotactic activity was significantly higher in acrylic (p < 0.05) and silicone (p < 0.05) IOLs compared to one of the PMMA lenses. Conclusions: This limited study has proven that chemotaxis assay is a useful tool to assess the biocompatibility of IOLs. The IOL material itself might attract inflammatory cells to its surface in the absence of surgical and host factors. As PMMA IOLs do not cause an increase in inflammatory reaction, they may be considered safe to use. Further improvement in chemical composition and surface characteristics of IOLs should reduce the inflammatory reaction and increase the biocompatibility and safety of IOLs.     

Uveal and capsular biocompatibility of hydrophilic acrylic, hydrophobic acrylic, and silicone intraocular lenses.

PURPOSE: To evaluate the long-term response of 6 types of 3-piece intraocular lenses (IOLs) by assessing the cellular reaction on the anterior IOL surface, the behavior of posterior and anterior capsule fibrosis, and flare. SETTING: Department of Ophthalmology, Medical School, University of Vienna, Vienna, Austria. METHODS: One hundred eighty eyes were prospectively randomized to receive 1 of 6 IOLs: hydrophilic acrylic Hydroview (Bausch & Lomb) or MemoryLens (ORC); hydrophobic acrylic AcrySof MA60BM (Alcon) or AMO Sensar AR40 (Allergan); hydrophobic silicone CeeOn 920 or CeeOn 911A (Pharmacia). The patients had standardized cataract surgery, postoperative medication, and follow-up. One year after surgery, 155 eyes were assessed. The cellular reaction was evaluated by specular microscopy of the anterior IOL surface. Anterior and posterior capsule opacification (PCO) was assessed semiquantitatively by biomicroscopy. Flare was measured with a Kowa FC-1000 laser flare-cell meter. RESULTS: Regarding uveal biocompatibility, the hydrophobic acrylic IOLs showed the highest incidence of late foreign-body cell reaction (AcrySof, 30%; AR40, 17%) followed by the hydrophilic acrylic (MemoryLens, 8%; Hydroview, 4%) and silicone (CeeOn 920, 4%; CeeOn 911A, 0%) (P =.0044). In all cases, the cellular reaction was low grade and clinically insignificant. Regarding capsular biocompatibility, some eyes developed lens epithelial cell (LEC) outgrowth on the anterior IOL surface. The highest incidence was in the hydrophilic acrylic group (Hydroview, 85%; MemoryLens, 27%) followed by the hydrophobic acrylic (AcrySof, 4%; AR40, 3%). No silicone IOL had LECs on the anterior surface. The difference among IOL groups was significant (P =.0001). Anterior capsule opacification was more predominant in the hydrophobic IOL groups. Posterior capsule opacification of the central 3.0 mm area was lowest in the groups with a sharp-edged optic (CeeOn 911A, AcrySof) followed by the round-edged silicone (CeeOn 920), hydrophobic acrylic (AR40), and hydrophilic acrylic IOLs (P =.0001). There was a significant difference in flare between the AR40 lens and the Hydroview, MemoryLens, CeeOn 911A, and CeeOn 920 (P <.004). There was no statistically significant difference in the postoperative cell count at 1 year. The power calculation showed that the sample size was sufficient. CONCLUSIONS: The differences in cellular reaction, although clinically mild in normal eyes, indicate that there were more giant cells with hydrophobic acrylic IOLs and an increased tendency toward LEC outgrowth with hydrophilic lenses. The incidence of PCO was lowest in the hydrophobic IOL groups, especially in groups with a sharp-edged optic. Second-generation silicone IOLs with a sharp edge had good uveal and capsular biocompatibility 1 year after surgery.