Foldable Silicone Research Articles

Evaluation of intraocular pressure with Healon and Healon GV in sutureless cataract surgery with foldable lens implantation

Purpose: To evaluate transient increases in intraocular pressure (IOP) after use of high-viscosity viscoelastic agents in cataract surgery.Setting: Military Hospital, Ulm, Germany.Methods: In a prospective, randomized study, we evaluated IOP following cataract surgery using two different viscoelastic substances (Healon®, Healon® GV). The viscosity of Healon GV is 10 times higher than that of Healon because of higher concentration and molecular weight. Patients having identical phacoemulsification procedures (sutureless clear corneal tunnel incision with foldable silicone lens implantation) (N = 60) and identical viscoelastic removal were assigned to groups of 15 based on viscoelastic used and removal time (20 or 40 seconds). Intraocular pressure was measured preoperatively and at 6, 24, 36, and 48 hours and 1 month postoperatively.Results: The highest mean IOP elevations in both viscoelastic groups were obtained at 24 hours postoperatively (2.9 mm Hg ± 4.3 [SD] with Healon and 3.3 ± 6.3 mm Hg with Healon GV). There were no statistically significant differences between the two viscoelastics and the two removal times during the entire follow-up period (unpaired t-test), but standard deviations were higher in the Healon GV groups at 6 and 24 hours. Two patients in the Healon groups and three in the Healon GV groups required medical treatment for IOP within the first 24 postoperative hours; however, all five patients had an IOP lower than 22 mm Hg on the second postoperative day.Conclusions: Based on postoperative IOP, both viscoelastics can be equally well removed from the anterior chamber. Incidence of high IOP using high-viscosity hyaluronic acid is minimized by the described removal technique.

Correlation between intraocular lens hydrophilicity and anterior capsule opacification and aqueous flare

Purpose: To study the correlation between a basic parameter of intraocular lens biocompatibility, hydrophilicity, and two clinical parameters, postoperative inflammation and anterior capsule opacification.Setting: Miyake Eye Hospital, Nagoya, Japan.Methods: Three combinations of IOLs that were identical in shape but had distinct contact angles of water were used in this prospective double-masked study: (1) experimental comparison of collagen type IV and poly(methyl methacrylate) (PMMA) IOLs in rabbit eyes; (2) clinical comparison of heparin-surface-modified and PMMA IOLs; (3) clinical comparison of three foldable IOLs, silicone, acrylic, and memory. One of the two IOLs being compared in each situation was randomly assigned to both eyes of each animal or patient. At 1 and 3 months postoperatively, the degree of anterior capsule opacification and the amount of flare in the anterior chamber were determined.Results: In all three comparative situations, greater postoperative inflammation and more rapid anterior capsule opacification was seen in the eyes with hydrophobic IOLs.Conclusion: There was a correlation between the hydrophilicity of an IOL and the severity of postoperative inflammation and the speed of anterior capsule opacification.

Bacterial anterior chamber contamination with foldable silicone lens implantation using a forceps and an injector

Purpose: To compare the rate of anterior chamber (AC) contamination during implantation of a foldable three-piece silicone lens using a forceps and an injector.Setting: Department of Ophthalmology, University of Saarland, Homburg (Saar), Germany.Methods: In a prospective, randomized study, we cultured AC aspirates of patients who had phacoemulsification with silicone lens implantation through a 3.5 mm temporal clear corneal incision. In Group A, the lens was implanted with a forceps and in Group B, with an injector. Immediately after lens implantation, the AC aspirate (0.05 to 0.10 ml) was collected and sent to the microbiology department. All cultures were incubated for 3 days. As a topical antibiotic, gentamicin was given preoperatively and intraoperatively.Results: One hundred patients (50 in each group) were examined. In each group the bacterial contamination of the AC was 2%.Conclusion: Bacterial contamination of the AC was not significantly different after silicone lens implantation with a forceps and with an injector.

Prospective study of the SI-40NB foldable silicone intraocular lens

Purpose: To evaluate the surgical performance and postoperative outcomes of 100 consecutive implantations of the new AMO PhacoFlex SI-40NB foldable intraocular lens (IOL).Setting: Concord Hospital and Dalcross Private Hospital, Sydney, Australia.Methods: This prospective study comprised 100 consecutive patients who had endocapsular phacoemulsification cataract surgery with implantation of the AMO SI-40NB IOL, which has a silicone optic and poly(methyl methacrylate) (PMMA) haptics. Patients were excluded if trabeculectomy was performed concomitantly. The main outcome measures were control of folding, ease of implantation, centration, intraoperative and postoperative complications, and visual acuity. A minimum of 4 months follow-up was planned.Results: Mean follow-up was 4.3 months ± 2.1 (SD) (range 1 to 12 months). The lens permitted excellent control of folding and insertion, as well as excellent centration at surgery and 4 months. There was one lens-related intraoperative complication because of crimping of the trailing lens haptic. Postoperative complications were minimal, and 92% of patients achieved a visual acuity of 20/20 or better at 1 and 4 months. Excluding the eyes with retinal pathology, 100% achieved 20/20 or better at 4 months.Conclusion: The AMO SI-40NB three-piece silicone IOL with PMMA haptics provided excellent operative control, centration, and visual outcome and is suitable for small incision cataract surgery.

Long-term follow-up of three-piece, looped, silicone intraocular lenses

Purpose: To present long-term follow-up of silicone lens implantation.Setting: Clinique Ophtalmologique, Centre Saint-Victor, Amiens, Cédex, France.Methods: In this prospective study, we followed 111 eyes consecutively operated on from March 1988 to July 1989. Foldable silicone intraocular lenses (IOLs) were implanted in 107 eyes and poly(methyl methacrylate) (PMMA) IOLs in 4 eyes. The eyes with PMMA lenses were excluded from the study.Results: After a follow-up of 3 years (average 20 months), 13.7% of eyes with posterior capsule opacification (PCO) required a neodymium:YAG (Nd:YAG) laser capsulotomy. In the group with longer follow-up (average 57 months), 40.6% required Nd:YAG capsulotomy. The majority of capsulotomies were performed in the fourth year after surgery. The PCO rate was the same whether the IOL was placed in the sulcus or in the capsular bag (51.5 versus 48.5%). The Nd:YAG treatment caused pitting of the silicone in most cases, with no effect on visual acuity. We did not observe other serious complications such as retinal detachment, endophthalmitis, or silicone discoloration. There was no visual acuity below 20/35.Conclusions: In this series, the silicone IOLs were compatible with phacoemulsification and did not have a higher rate of complications than has been reported for PMMA IOLs.

Long-term endothelial cell loss following phacoemulsification through a temporal clear corneal incision

Purpose: To evaluate central endothelial cell loss (ECL) following clear corneal cataract surgery using two different incision sizes and the effect of ultrasound time (UST) and power on postoperative ECL and various cell parameters.Methods: Fifty-eight patients had phacoemulsification through temporal, two-step clear corneal tunnel incisions. In Group A (n = 28), a one-piece, plate-haptic, foldable silicone intraocular lens (IOL) was implanted through a 3.5 mm sutureless incision. In Group B (n = 30), a poly(methyl methacrylate) IOL was implanted through a 5.0 mm incision with one radial suture. The central endothelial cell counts were recorded preoperatively and postoperatively at 2 to 5 days, after 6 months, and after 1 year. Color-coded, computer-assisted specular microscopy was used for special cell analysis after 1 year.Results: Collective data showed an ECL of 7.9 ± 4.1 % (mean ± standard deviation) at 2 to 5 days postoperatively, 6.7 ± 2.9% after 6 months, and 7.3 ± 3.3% after 1 year. A direct linear relationship was found between ECL and UST and power: ECL increased as UST and power increased. After 1 year, ECL in Group A was 4.2% with UST ≤1 1/2 minutes, 6.7% with UST ≥ 1 1/2 to 2 1/2 min, and 9.6% with UST > 2 1/2 to 3 1/2 min; in Group B, it was 6.0%, 7.5%, and 11.4%, respectively. Specular microscopy showed normal, age-related cell parameters 1 year postoperatively.Conclusions: Phacoemulsification with 3.5 mm clear corneal incisions produced slightly less ECL (6.7%) than phacoemulsification with 5.0 mm incisions (7.9%). Total ECL of 7.3% at 1 year postoperatively compared favorably with ECL rates of other cataract extraction methods.

Comparism of one piece PMMA-intraocular lenses with foldable one-piece plate-haptic silicone lenses in terms of postsurgical lenticular astigmatism

Comparism of one piece PMMA-intraocular lenses with foldable one-piece plate-haptic silicone lenses in terms of postsurgical lenticular astigmatism

P 238 Comparism of the piece PMMA-intraocular lenses with foldable one-piece plate-haptic silicone lenses in terms of postsurgical lenticular astigmatism

P 238 Comparism of the piece PMMA-intraocular lenses with foldable one-piece plate-haptic silicone lenses in terms of postsurgical lenticular astigmatism

Oberflächenqualität faltbarer Intraokularlinsen aus Silikon - Eine rasterelektronenmikroskopische Studie

Soft intraocular lenses (IOLs) have been developed to be folded during insertion to allow implantation through a small incision. The surface of the IOL is of great importance in postoperative inflammation and long-term acceptance of the implant. Rough and sharp edges can damage delicate intraocular tissues. The purpose of this study was to analyze new, foldable silicone IOLs for surface quality prior to and following folding. Eleven silicone IOLs of different types were included in this study (four one-piece plate-haptic silicone IOLs and seven three-piece silicone IOLs with polypropylene, PMMA or polyimid haptics). We performed scanning electron microscopy on brand-new IOLs prior to and following folding either with forceps or inserter. Special attention was given to the silicone optic surface, optic edges, haptic-optic junctions and the haptic itself. Photographs were taken at 5-350 times magnification. All IOLS demonstrated a smooth and homogeneous optic surface at low magnification. At high-power magnification (X 350), distinctive surface patterns were evident in some IOLs, which turned out to be artefacts. The edge finish showed surplus silicone material and molding flash in six of 11 IOLs. Positioning holes of the 4 plate-haptic IOLs were, except in one IOL, rounded and not rough. Photographs of the haptic-optic junctions revealed surplus material or clefts between the haptic and optic in six of the 7 three-piece IOLs; the loop ends of two IOLs showed a roughened or irregular surface. We did not detect any IOL changes produced by folding. The silicone IOLs tested demonstrated generally acceptable surface properties, but most IOLs had regional surface irregularities of varying magnitude. The clinical impact of these remains to be established, but surplus material or surface defects might result in deposition of inflammatory cells, protein or microorganisms and synechia formation. Folding of the IOLs did not produce superficial defects.

Fibrin Glue in Temporal Clear Corneal Tunnel Incision

OBJECTIVE: While 3.5 mm clear corneal incisions for the implantation of foldable silicone lenses are commonly accepted, longer incisions for PMMA-IOL implantation are associated with a possibly higher risk of infection and less self-sealing properties. DESIGN: It was intended to reinforce the 5 mm clear corneal tunnel incision after phacoemulsification and IOL-implantation with fibrin adhesive. SETTING: Department of Ophthalmology, University of Giessen, Germany. METHODS: Upon simultaneous mixing of fibrinogen complex and thrombin, the final stages of the coagulation cascade are mimicked after application of fibrin glue, resulting in formation of a fibrin clot. MAIN OUTCOME: The sealant consolidated and adhered to the site of corneal application. The present case demonstrated that fibrin glue is efficacious in watertight wound closure of 5 mm clear corneal incision and provides good support for corneal healing. Only minimal surgically-induced with-the-rule astigmatism was observed. CONCLUSION: In the future, this technique of corneal wound closure might develop as an alternative to singlesuture wound closure after small incision cataract extraction.

Comparison of the induced astigmatism after temporal clear corneal tunnel incisions of different sizes

A prospective, randomized study compared the surgically induced astigmatism after 3.5 mm, 4.0 mm, and 5.0 mm temporal corneal tunnel incisions over six months. We studied 60 eyes of 60 patients who had phacoemulsification through a two-step clear corneal tunnel incision and implantation of one of three posterior chamber intraocular lenses (IOLs). Patients were divided into three groups of 20 each: Group A, cartridge injection of a foldable plate-haptic silicone IOL through a 3.5 mm self-sealing incision; Group B, cartridge injection of a disc silicone IOL through a 4.0 mm self-sealing incision; Group C, 5.0 mm optic poly(methyl methacrylate) IOL through a 5.0 mm incision with one radial suture. Corneal topography data were obtained using a computerized videokeratographic analysis system preoperatively and one week and six months postoperatively. Vector analysis was performed to calculate the surgically induced astigmatism. After the first postoperative week, mean induced astigmatism was 0.63 diopters (D) (±0.41) in Group A, 0.64 D (±0.35) in Group B, and 0.91 D (±0.77) in Group C. After six months, it was 0.37 D (±0.14) in Group A, 0.56 D (±0.34) in Group B, and 0.70 D (±0.50) in Group C. Surgically induced astigmatism was significantly lower in Group A than in Group B (P < .05) and Group C (P < .005) after six months. Vector analysis demonstrated that temporal corneal tunnel incisions induced clinically minimal astigmatism over six months postoperatively depending on incision size.

Condensation on the Posterior Surface of Silicone Intraocular Lenses during Fluid—Air Exchange

Posterior chamber foldable silicone intraocular lenses (IOLs) are becoming increasingly prevalent in patients undergoing a pars plana vitrectomy with fluid-air exchange. The authors report an important limitation of foldable silicone IOLs during fluid-air exchanges in pars plana vitrectomies. The charts of 18 pseudophakic patients with foldable silicone IOLs who underwent vitrectomy with fluid-air exchange by the authors were reviewed. There was a statistically significant difference in the occurrence of condensation during fluid-air exchange between the group of patients with a capsulotomy versus those that did not have a capsulotomy (P = 0.003). Condensation limiting the view of the retina occurred during fluid-air exchange in 11 of 11 of the patients with foldable silicone lenses and a capsulotomy. Attempts to remove the condensation with a soft-tipped aspiration cannula resulted in limited view of the retina for 1 to 2 minutes in 6 of 11 patients. Use of a thin film of silicone oil restored the view in one patient. In the presence of an intact posterior capsule, condensation did not occur on identical foldable silicone IOLs in seven of seven patients. Recognition of the presence of a foldable silicone lens is important when an air-fluid exchange is anticipated. If a capsulotomy is present, the surgeon must be aware that condensation may limit the view of the retina severely during and after surgery. Intraoperatively, the view of the retina usually can be restored in short surgeries by wiping the posterior lens surface with a soft-tipped cannula, and in more complex surgeries by applying a thin film of silicone oil on the posterior surface of the lens.

Implant intraoculaire monobloc en silicone et fibrose de la capsule antérieure

Foldable plate haptic silicone intraocular lenses (IOLs) were surmised to produce greater anterior capsule fibrosis than poly(methyl metacrylate) (PMMA) intraocular lenses. A retrospective study of 34 eyes was carried out 12 to 15 months after phacoemulsification. All surgical procedures were performed by the same surgeon (M.G.) using two different techniques: 17 eyes were operated on through a temporal clear-cornea incison and implanted with a foldable plate haptic silicone IOL (STAAR AA4203); 17 eyes were operated on through a superior sclerocorneal incision and received a PMMA IOL (Kabi Pharmacia 809P). Secondary opacification of the anterior capsule was compared between the two groups. Seventy percent of eyes (12/17) with plate haptic silicone IOL had moderate or important anterior capsule fibrosis or shrinkage. Only 18% of eyes (3/17) with PMMA IOL presented with this complication. However, posterior capsule opacification was almost similar in both groups. Foldable plate haptic silicone IOLs seem to produce a more important anterior capsule fibrosis or shrinkage than PMMA IOL one year after phacoemulsification and saccular implantation. Although etiology is unknown, either huge contact between IOL and anterior capsule, or lack of contact between anterior and posterior capsules are hypotheses advanced. Posterior capsule opacification is similar in the two groups.

Endothelial cell loss after 4 mm cataract surgery

To assess whether a 4 mm scleral tunnel incision with a 1.5 mm internal corneal lip (three-step procedure) causes increased endothelial cell loss and damage to the cornea, we retrospectively evaluated the outcomes of 20 patients (40 eyes) who had a standard 4 mm scleral tunnel incision (two-step procedure) in one eye followed by a three-step incision in the second eye, with in situ phacoemulsification and insertion of a foldable silicone lens in each eye. Mean phacoemulsification time was 2.4 ± 1.1 minutes for the two-step incisions and 3.4 ± 1.4 minutes for the three-step incisions. Preoperative and postoperative endothelial cell counts were obtained to determine the effects of surgery on the corneal endothelium. Although the three-step procedure had a trend toward increased endothelial cell loss from the central corneal region compared with the two-step incision, the result was neither clinically nor statistically significant. The difference between the three-step and two-step incisions in postoperative endothelial cell counts from the superior corneal region was statistically significant. The difference in postoperative counts from the inferior region was not statistically significant. Although the three-step 4 mm incision does seem to affect the corneal endothelium, its clinical significance is unknown.

Astigmatic changes after cataract surgery with 5.1 mm and 3.5 mm sutureless incisions

We evaluated postoperative keratometric astigmatism in 80 eyes that had phacoemulsification and intraocular lens implantation through sutureless corneal incisions. The eyes were separated into two groups based on the use of rigid ovoid or foldable silicone lenses inserted through 5.1 mm corneal lip incisions or 3.5 mm lip incisions, respectively. In the early postoperative period (one to three months), vector analysis showed less induced astigmatism in the 3.5 mm group than in the 5.1 mm group. Uncorrected visual acuity during the postoperative period was also better in the smaller incision aroun

In-the-bag Implantation of the PhacoFlex SI-30 Highrefractive Silicone Lens Through Self-sealing Sclerocorneal and Clear Corneal Incisions

Objective: Performance of a new foldable open-loop silicone lens when implanted through a small incision into a rhexis bag. Study Design: Prospective study with a mean follow-up of 5.9+/-1.6 months, minimum 3 months. Setting: First University Eye Hospital, Vienna. Patients: 35 patients each received the implant through a 3.2 mm superior sclerocorneal or a 3.0 mm temporal clear corneal self-sealing tunnel incision, using two types of implantation forceps. Main Outcome Measures: Manoeuvrability, ease of implantation, capsular bag residence, optic-iris clearance, biocompatibility, visual acuity, keratometry, computerized corneal topography. Results: Excellent control of folding and insertion, good centration with round, well-centered 4–5 mm capsulorhexis opening, visual acuity = >20/30 in all and = >20/25 in 95% of best cases, corneal shape essentially unaltered; four minor (5.7%) and two moderate decentrations (2.90/0) due to an improperly shaped rhexis and/or an optic-edge-by-rhexis capture, four cases (5.7%) of partial buttonholing of optic through adequately shaped rhexis; bluish tint and granularity of silicone optic a regular but clinically insignificant observation. Conclusions: PhacoFlex SI-30 lens meets criteria for real small-incision, including sutureless clear corneal cataract surgery. Enhanced loop rigidity may optimize intraocular performance.

Langzeitergebnisse nach Implantation faltbarer Silikon-Hinterkammerlinsen

Prospective analysis of long-term results after small incision no-stitch phacoemulsification with implantation of foldable silicone IOL. In 100 consecutive patients we implanted through a 3.2 mm incision a STAAR-silicone IOL model AA4203. Uncorrected and best-corrected visual acuity, surgically induced astigmatism and postoperative complications were examined at 1 day, 3 months and 1 year after surgery. On day 1 postop. 75% of the patients achieved uncorrected visual acuity of 0.5 or more. The mean best corrected visual acuity at day 1 was 0.75 (0.22 SD). The vector analysis of the surgically induced astigmatism does not show any difference between day 1 and 1 year postop. with a mean induced astigmatism of 0.73 dpt. 12 Months after surgery we found 3 cases of cystoid macula edema and 3 cases of clinically significant secondary cataract. The clinical long-term results after implantation of foldable silicon-IOL are comparable with the results after implantation of rigid PMMA lenses. The optical rehabilitation is much faster and contributes to lower the costs of modern cataract surgery.

Centration, Endothelial Cell Count and Functional Results after Implantation of Foldable Silicone Lenses

Objective: Long-term evaluation of astigmatism, visual acuity, endothelial cell count and intraocular lens decentration after implantation of a 6.0 mm flexible silicon lens. Study Design: A prospective study with examination of the patients one day, one week, 3, 6,12,18 and 24 months post-operatively with comparison of the pre-operative status. Patients: 30 patients (aged 59 ± 12 years) were followed for 24 months. Main Outcome Measures: Visual acuity, astigmatism, endothelial cell count, decentration of the intraocular lens. Results: After 24 months visual acuity reached 1.05 (±0.24), the astigmatism was −0.35 ± 0.5), and the total endothelial cell loss was below 20%. All lenses remained centred in the capsular bag with a mean deviation from the optical axes of only 64μ ± 39μ. Conclusions: We conclude that these small scleral incisions required for flexible silicon IOL shortens the time for rehabilitation and revealed no severe dislocation of the implant after 24 months.

Long-term results of implantation of a plate haptic silicone lens in the capsular sac

An important step in developing cataract surgery was the introduction of soft foldable silicone intraocular lenses in the middle 80's. Functional and morphological long-term data are a vital base for definite conclusions on the new material's safety and biocompatibility. Our study presents the long-term results after the implantation of a silicone posterior chamber lens with solid plate haptic design (STAAR AA-4203). All lenses were folded and implanted through a 4-mm small corneoscleral incision. Our study includes 54 eyes in 52 patients with a mean follow-up period of 56.5 +/- 8.9 months. A visual acuity of 20/40 or better was found in 90.7% of all eyes. All except one of the 33 eyes without any further preexisting ocular pathology at the time of the operation achieved a visual acuity of 20/40 or better. Two thirds of all eyes had a horizontal astigmatism of +1.0 D or less. By slitlamp examination more or less dispersed pigment was seen on the IOL's surface in 46.3%. 83% of the silicone lenses were centrated within 0.5 mm. A YAG-laser capsulotomy was performed in 7 cases (13%). IOL-related intraocular inflammations, cystoid macular edema or an elevated intraocular pressure did not occur in this group. Our satisfactory long-term results suggest an excellent biocompatibility of the IOL's design and material.

Corneal lip tunnel incision

To evaluate whether the corneal lip tunnel incision or the sutureless closure causes any refractive problems, we performed a retrospective study on 387 cataract surgery patients who were divided into four groups based on type of wound closure and whether the corneal lip was made. The four groups consisted of patients who received an X-stitch closure without the corneal lip, a horizontal mattress stitch without the lip, a horizontal mattress stitch with the lip, and a sutureless closure with the lip. All patients had phacoemulsification in situ; implantation of a foldable silicone lens was performed through a scleral tunnel incision. Clinical evaluations included preoperative characteristics and postoperative Snellen visual acuity, intraocular pressure, and vector analysis of cylinder. In all four groups, a 4.0 mm wide incision was used. Entrance into the clear cornea during the corneal lip tunnel incision did not induce additional cylinder, and the sutureless closure did not decrease induced cylinder or increase the against-the-rule shift. The results of this study indicate that the combination of a 4.0 mm incision with 1.5 mm corneal lip, phacoemulsification in situ, foldable lens implantation, and sutureless closure is a safe and effective procedure for cataract surgery.