Comparison of the biocompatibility of 2 foldable intraocular lenses with sharp optic edges

The outcomes of cataract surgery in eyes with Fuchs uveitis

BACKGROUND

To evaluate clinical results in eyes undergoing phacoemulsification intraocular lens (IOL) implantation due to Fuchs^, uveitis (FU) related complicated cataract.

METHODS

Post-surgical outcomes of 56 eyes of 55 FU patients were evaluated retrospectively. Three groups were formed according to the IOL model: hydrophilic SAF6125 (Optima fold) acrylic, hydrophobic SN60AT (Alcon), and hydrophobic AAB00 (Abbott). Postoperative posterior capsular opacification (PCO) development and PCO development time, neodymium number: YAG laser posterior capsulotomy rate, giant cell (GC) deposition on the IOL, and the development time of GC deposits were compared among the groups. All patients were followed postoperatively on the 1^st day, 1^st week, 2^nd and 6^th weeks, and then at 3-month intervals.

RESULTS

The hydrophilic SAF6125 IOL was implanted in 10 eyes, hydrophobic SN60AT in 24 eyes and AAB00 IOL in 22 eyes. The mean postoperative follow-up time was 34.1 ± 30.1 (6-144) months. PCO developed in 7 eyes (70%) in the hydrophilic SAF6125 group, 17 eyes (70.8%) in the hydrophobic SN60AT and 13 eyes (59.1%) in the AAB00 group. There was no statistically significant difference among the three IOL groups in the PCO development, the PCO development time and YAG laser capsulotomy rates (P = 0.674, P = 0.111, and P = 0.507, respectively). The PCO development time was significantly longer in the hydrophobic SN60AT than AAB00 group (P = 0.027). GC deposits were detected in 3 eyes (30%) in the hydrophilic SAF6125 group, 7 eyes (29.1%) in the hydrophobic SN60AT and 3 eyes (13.6%) in the AAB00 group. GC deposition and the development time of GC deposits were similar among the three IOL groups (P = 0.575, P = 0.804). At the final follow-up, BCVA was ≥ 20/40 in 41 eyes (73.2%).

CONCLUSION

The GC deposits and PCO development were the most important problems in these eyes with hydrophilic or hydrophobic IOLs despite good visual and postoperative results. New developments are needed in terms of IOL design or content in eyes with FU.

Amphiphilic silicones to mitigate lens epithelial cell growth on intraocular lenses

Silicone intraocular lenses (IOLs) that resist lens epithelial cell (LEC) growth would greatly improve patient outcomes. Herein, amphiphilic surface modifying additives (SMAs) were incorporated into an IOL-type diphenyl silicone to reduce LEC growth without compromising opto-mechanical properties. The SMAs were poly(ethylene oxide)-silane amphiphiles (PEO-SAs) [H-Si-ODMS_m-block-PEO₈-OCH₃], comprised of a PEO segment and siloxane tether of varying lengths (m = 0, 13, and 30). These three SMAs were each blended into the addition cure diphenyl silicone at varying concentrations (5, 10, 15, 20, and 25 μmol g^-1) wherein the wt% of PEO was maintained for all SMAs at a given molar concentration. The chemical crosslinking and subsequent retention of SMAs in modified silicones was confirmed. Key material properties were assessed following equilibration in both air and aqueous environments. Silicones modified with SMAs having longer tethers (m = 13 and 30) underwent rapid and substantial water-driven restructuring of PEO to the surface to form highly hydrophilic surfaces, especially as SMA concentration increased. The % transmittance was also maintained for silicones modified with these particular SMAs. The moduli of the modified silicones were largely unchanged by the SMA and remained in the typical range for silicone IOLs. When the three SMAs were introduced at the highest concentration, modified silicones remained non-cytotoxic and LEC count and associated alpha-smooth muscle actin (α-SMA) expression decreased with increasing tether length. These results demonstrate the potential of silicones modified with PEO-SA SMAs to produce LEC-resistant IOLs.

Application of Collagen I and IV in Bioengineering Transparent Ocular Tissues

Collagens represent a major group of structural proteins expressed in different tissues and display distinct and variable properties. Whilst collagens are non-transparent in the skin, they confer transparency in the cornea and crystalline lens of the eye. There are 28 types of collagen that all share a common triple helix structure yet differ in the composition of their α-chains leading to their different properties. The different organization of collagen fibers also contributes to the variable tissue morphology. The important ability of collagen to form different tissues has led to the exploration and application of collagen as a biomaterial. Collagen type I (Col-I) and collagen type IV (Col-IV) are the two primary collagens found in corneal and lens tissues. Both collagens provide structure and transparency, essential for a clear vision. This review explores the application of these two collagen types as novel biomaterials in bioengineering unique tissue that could be used to treat a variety of ocular diseases leading to blindness.

Biomaterial Influence on Intraocular Lens Performance: An Overview

There is strong evidence that the IOL material is the factor having the greatest impact on posterior capsule opacification (PCO), anterior capsule opacification (ACO) development, and glistening formation after cataract surgery, even though there are other IOL features—such as haptic material and design and edge and optic design—that also have some influence. We reviewed the published literature describing the adverse events that are mainly related to the intraocular lens (IOL) material, such as PCO, ACO, and the subsequent capsule contraction, as well as glistening formation. The adverse events presented in this overview are the most common ones in clinical practice, and therefore, they are generally included in the clinical protocols for IOL evaluation.

In Vitro Analysis of AcrySof Intraocular Lens Glistening

PURPOSE

The authors studied the effects of changes in packaging solution temperature on the development of glistening in acrylic intraocular lenses (AcrySof, Alcon).

METHODS

Glistening was examined by slit lamp at each condition. In Experiment 1, AcrySof lenses were soaked in physiologic saline adjusted to 15 degrees C and 37 degrees C in an incubator. In Experiment 2, AcrySof lenses were soaked in physiologic saline adjusted to 37 degrees C and 60 degrees C for 5 min, then stored in physiologic saline adjusted to 15 degrees C. In Experiment 3, glistening formation was induced in AcrySof lenses by soaking them in warm water (37 degrees C). The lenses were allowed to dry at 15 degrees C and then soaked in physiologic saline adjusted to 15 degrees C. After storage of dry AcrySof lenses at 37 degrees C in an incubator for 10 months followed by soaking in physiologic saline adjusted to 15 degrees C, glistening formation was evaluated in Experiment 4.

RESULTS

Glistening became observable after 1 month, despite the temperature having been lowered to 15 degrees C. No glistening was observed in the lenses soaked in physiologic saline adjusted to 37 degrees C after 5 min, but glistening was observed 1 month after soaking. When allowed to dry at 15 degrees C, the glistening decreased. After 1 month of soaking at 15 degrees C, glistening was again observable.

CONCLUSIONS

AcrySof lenses soaked in warm water for a short time may change characteristics, and therefore, close monitoring of the temperature and time of soaking is necessary to prevent glistening formation.

Glistening in glaucomatous eyes: visual performances and risk factors

PURPOSE

To analyse risk factors and visual performances of glaucomatous eyes with glistening in the intra-ocular lens (IOL).

METHODS

Prospective study performed between November 2010 and April 2011 and involving 67 consecutive glaucomatous eyes (47 patients), who previously had a phacoemulsification with a hydrophobic acrylic IOL implanted in the capsular bag. Glistening was classified in three groups of severity grade: G0 (<50 microvacuoles per mm(2) ), G1 (50-150 microvacuoles per mm(2) ), and G2 (>150 microvacuoles per mm(2) ). All eyes underwent a best-corrected visual acuity evaluation (BCVA, LogMAR scale), a complete clinical examination, a visual field test, a contrast sensitivity evaluation and a wavefront analysis of high-order aberrations (HOAs) using a Shack-Hartmann aberrometer. Eyes with a posterior capsular opacification and a BCVA>0.30 LogMAR were excluded.

RESULTS

Twenty six eyes (38.8%) had a grade 0, 12 eyes (17.9%) a grade 1 and 29 eyes (43.3%) a grade 2 of glistening severity grade. The mean follow-up after cataract surgery was 35.2 ± 24.2 months and was significantly higher for G1 and G2 groups (p < 0.001). A higher number of topical glaucoma medication were associated with a higher glistening severity grade (p < 0.05). G1 and G2 groups had significantly lower mean contrast sensitivity values at high spatial frequencies and significantly higher loss variance (LV) values of the visual field test (p < 0.05). There was no significant difference in mean BCVA between groups (p = 0.455).

CONCLUSIONS

In glaucomatous eyes, glistening increased with time was associated with the number of topical glaucoma medications daily instilled and altered visual performances. It should be a consideration for glaucoma patients who are more likely to develop glistening within the IOL optic.

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.

Incidence of glistenings with the latest generation of yellow-tinted hydrophobic acrylic intraocular lenses

PURPOSE

To evaluate the incidence of glistenings in a large series of consecutive eyes with a blue light-filtering hydrophobic acrylic intraocular lens (IOL) and the relationship with parameters such as age, sex, follow-up length, and corrected distance visual acuity (CDVA).

SETTING

Service d'Ophtalmologie, Centre Hospitalier et Universitaire Bordeaux, Bordeaux, France.

DESIGN

Cross-sectional study.

METHODS

This study included 111 eyes of 74 patients (age range 33 to 86 years). All cases had cataract surgery with Acrysof SN60WF monofocal IOL implantation and had a routine postoperative examination between March 2011 and June 2011. The incidence and severity of glistenings were evaluated with the slitlamp. Also evaluated was their relationship with age, sex, follow-up length, IOL power, and CDVA. Glistenings were subjectively graded (0 = absent; 1 = moderate; 2 = dense).

RESULTS

Glistenings occurred in 96 eyes (86.5%). Glistenings were of grade 1 severity in 45 eyes (40.5%) and of grade 2 severity in 51 eyes (45.9%). The follow-up was significantly longer in eyes with grade 2 glistenings (P ≤ .01). A limited, but significant, correlation was found between glistening severity and length of follow-up (r = 0.32, P<.01). Although there was a trend toward decreased visual acuities at higher glistening grades (r = 0.22, P = .01), there were no significant differences in CDVA between the glistening severity groups (P = .14).

CONCLUSIONS

Glistenings were common in eyes with the blue light-filtering hydrophobic acrylic IOL and increased over time.

FINANCIAL DISCLOSURE

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

Modern cataract surgery: unfinished business and unanswered questions

We summarize information, based on clinicopathologic studies over the past decade, on various cataract intraocular lens (IOL) procedures and modern "specialized" IOLs, that will help surgeons continuously improve long-term results for cataract patients. Although most operations do initially provide excellent refractive correction and visual rehabilitation, late complications occur. These sometimes are missed because they are outside of the routine period of follow-up care. We have tried to determine if the various techniques and IOLs truly deliver the long-term results that we desire. Most safety and efficacy information is derived from the manufacturer and is passed through the U.S. Food and Drug Administration (FDA). This is often based on limited, relatively short-term observations made by the manufacturer. After a lens receives FDA approval, there are few means to assess the outcome of each procedure and lens years later. We rarely hear of a 10- or 20-year follow-up study. We have found that one of the best means to assess long-term results is pathologic analyses. We discuss recently studied aspects of pathologic reactions, such as posterior capsule opacification, intracapsular fibrosis, glistenings, intralenticular opacification, and other issues with the various IOL platforms; we then present a clinicopathological overview of tissues and IOLs from our database. These include hydrophobic and hydrophilic acrylic designs, plate lenses, and a dual optic lens.

[Subluxation of hydrophilic acrylate intraocular lenses due to massive capsular fibrosis]

BACKGROUND

Compared with other biomaterials, hydrophilic acrylate provides better uveal biocompatibility, lower adhesion rates of bacteria and silicone oil, and less glare. Because of reduced capsular biocompatibility, increased fibrosis may initiate dislocation of the intraocular lens (IOL).

PATIENTS

In six eyes of four patients, enhanced fibroses led to IOL dislocation, leading to an IOL exchange an average of 40 weeks after implantation of the same hydrophilic acrylate lens type.

DISCUSSION

Predisposing factors were found in 90% of all reported cases of IOL dislocation in the literature, but not in the cases described here. The lens type that was implanted was unable to adapt to the massive fibrosis induced by its hydrophilic biomaterial.

CONCLUSIONS

The pattern of lens opacification should receive attention when one is choosing an IOL type. Eyes showing pseudoexfoliation syndrome as well as post-uveitis eyes might require a hydrophilic IOL for less cellular reaction, whereas a posterior subcapsular cataract might need a hydrophobic IOL to prevent a massive capsular fibrosis. In the case of increased capsular contraction, unreflected YAG laser capsulotomy may result in IOL subluxation when the lens design cannot handle capsule shrinkage, as demonstrated here.

Comparison of orbital floor triamcinolone acetonide and oral prednisolone for cataract surgery management in patients with non-infectious uveitis

PURPOSE

To compare orbital floor triamcinolone acetonide and oral prednisolone in cataract surgery in patients with chronic non-infectious uveitis with regard to visual outcome, postoperative inflammation and macular edema.

METHODS

Monocentric prospective randomized clinical trial with 40 eyes included. Patients underwent phacoemulsification with intraocular acrylic foldable lens (IOL) implantation. Patients were randomized either to intraoperative orbital floor triamcinolone acetonide (TA) (1 ml = 40 mg) (group 1, n = 20), or to 4-week postoperative oral prednisolone (group 2, n = 20). Laser flare photometry (LFM), cells in the anterior chamber (AC), best-corrected visual acuity (BCVA), IOL cell deposits, cystoid macular edema (CME) by means of fluorescein angiography, and central foveal thickness (OCT), posterior capsule opacification (PCO), and intraocular pressure (IOP) were analysed during a 6-months period.

RESULTS

Mean BCVA postoperatively improved (p < 0.01) from logMAR 0.74 and 0.86 to 0.23 and 0.35 in groups 1 and 2 respectively.The number of AC cells, LFM and IOL cell deposits did not differ. Macular edema stayed unchanged in most cases in both groups, and mean foveal thickness (OCT) initially increased postoperatively, but after 6 months it nearly returned to baseline thickness. Differences between the groups were not significant. Up to 12% in group 1 and 28% of group 2 developed IOP elevation over 21 mmHg.

CONCLUSIONS

A single intraoperative orbital floor injection of triamcinolone acetonide is as effective on postoperative inflammation, macular edema, and visual outcome as a 4-week course of postoperative oral prednisolone in cataract surgery with IOL implantation in uveitis patients.

Impact of fibronectin on surface properties of intraocular lenses

PURPOSE

Physical properties of intraocular lens (IOL) surfaces determine biocompatibility. IOL hydrophobicity of commercially available IOLs with and without fibronectin (FN) coating can be determined by surface contact angle (SCA) measurements. SCA data of IOLs may allow for a rational selection of an IOL type as a function of underlying eye disease.

SETTING

University Hospital of Saarland, Homburg (Saar), Germany

METHODS

Thirteen IOL types were tested. IOLs were made of poly(methyl methacrylate)(PMMA), acrylate, or silicone. Select IOLs were surface modified by the manufacturer with heparin or a polysaccharide coating. SCA values of IOLs, either uncoated or precoated with FN, were determined using the sessile water drop method.

RESULTS

SCA values ranged from 61.3 to 116.1 degrees for unmodified IOLs, with PMMA IOLs being more hydrophilic (median SCA, 74.1 degrees ), silicone IOLs more hydrophobic (median SCA, 113.3 degrees ), and acrylate IOLs intermediate (median SCA, 86.6 degrees ). Upon FN coating, all genuine acrylate lenses became significantly more hydrophilic while this effect was either nonsignificant or opposite on some PMMA and silicon IOLs. Heparin or polysaccharide surface modification resulted in significantly reduced SCA values. On acrylate IOLs, SCA values did not correlate with the aqueous content of the material.

CONCLUSIONS

This study associates IOL materials, surface modifications, and the role of FN preadsorption with SCA values reflecting surface hydrophobicity versus hydrophilicity. It provides a rationale for specific IOL selection as a function of the clinical setting, and a basis for IOL development using tailored surface physicochemistry to enhance biocompatibility and to reduce susceptibility to implant infection.

Posterior capsule opacification in silicone and hydrophobic acrylic intraocular lenses with sharp-edge optics six years after surgery

PURPOSE

To compare posterior capsule opacification (PCO) between 2 three-piece intraocular lenses (IOLs) both with sharp-optic edges and open loop haptics, one made of silicone and the other made of hydrophobic acrylate, 6 years after surgery.

DESIGN

Randomized, controlled, patient- and examiner-masked trial with intra-patient comparison.

METHODS

One hundred and six eyes in 53 patients were included initially. Forty-four eyes of 22 patients with age-related bilateral cataract were available for the 6 years follow-up. Each patient had standard cataract surgery and randomly received a silicone (CeeOn 911A; AMO, Santa Ana, California, USA) or hydrophobic acrylic (AcrySof MA60BM; Alcon, Fort Worth, Texas, USA) IOL in the first eye, the other type of IOL in the fellow eye. Follow-up examinations were at 1, 3, and 6 years after surgery. The intensity of posterior capsule opacification (PCO) was assessed using digital retro-illuminated photos and the "automated quantification of after-cataract" (AQUA) software. Neodymium-yttrium-aluminum-garnet-laser capsulotomies (YAG-LC) performed were noted.

RESULTS

Six years after surgery, the AQUA scores were 2.3 +/- 1.4 for the silicone and 3.8 +/- 2.0 for the acrylic IOLs (P = .0016). The acrylic IOL eyes also had a significant increase in AQUA score from the 3-year to the 6-year follow-up. YAG-LC were performed in 2 silicone and 6 acrylic IOLs (P = .01).

CONCLUSIONS

An angulated three-piece hydrophobic acrylic IOL had more PCO 6 years after surgery than a silicone IOL of otherwise similar design. Apart from an optic material effect, differences in haptic design and the degree of optic edge sharpness may play a role.

Comparison between intravitreal and orbital floor triamcinolone acetonide after phacoemulsification in patients with endogenous uveitis

PURPOSE

To compare the effect of intravitreal and orbital floor triamcinolone acetonide (TA) on macular edema, visual outcome, and course of postoperative inflammation after cataract surgery in uveitis patients.

DESIGN

Prospective, randomized clinical trial.

METHODS

Monocenter study (40 patients) with chronic endogenous uveitis who underwent phacoemulsification with intraocular lens implantation with either 4 mg intravitreal TA (n = 20) or 40 mg orbital floor TA (n = 20). The primary outcome was influence on cystoid macular edema (CME). Secondary outcome measures were best-corrected visual acuity (BCVA), anterior chamber cell grade, laser flare photometry, giant cell deposition, posterior capsule opacification (PCO), and intraocular pressure.

RESULTS

Mean central foveal thickness decreased in the intravitreal TA group and increased in the orbital floor TA group (P < .001 at one and three months). CME improved in 50% of patients after intravitreal TA, whereas it was unchanged after orbital floor TA (difference between the groups at three months, P = .049). Mean BCVA (logarithm of the minimal angle of resolution) improved postoperatively (P < .001) from 0.76 and 0.74 to 0.22 and 0.23 in the intravitreal TA and orbital floor TA group, respectively. Anterior chamber cell count at one month was lower in the intravitreal TA than in the orbital floor TA group (P = .02). Laser flare photometry values and giant cell numbers were slightly higher after orbital floor TA than after intravitreal TA. The groups did not differ with respect to PCO rate and ocular hypertension.

CONCLUSIONS

The CME improvement and anti-inflammatory effect after intravitreal TA was better than after orbital floor TA injection in cataract surgery in uveitis patients.

Two-year follow-up of posterior capsule opacification after implantation of a hydrophilic or hydrophobic acrylic intraocular lens

PURPOSE

To evaluate posterior capsule opacification (PCO) 2 years after cataract surgery following implantation of a hydrophilic or a hydrophobic single-piece acrylic intraocular lens (IOL) with a sharp edge.

METHODS

Phacoemulsification cataract surgery was performed in one eye of 120 patients with senile cataract in this prospective study. They were randomized to implantation of either a hydrophilic acrylic IOL (BL27; Bausch & Lomb, Rochester, NY, USA) or a hydrophobic acrylic IOL (AcrySof) SA60AT; Alcon Laboratories, Fort Worth, TX, USA). Two years after surgery, retroillumination images were obtained and PCO area and severity were evaluated using pocoman software. Best corrected visual acuity (VA) (both high-contrast [100%] and low-contrast [2.5%]), glare, laser flare and intraocular pressure were measured. Capsulotomy rates were recorded.

RESULTS

Patients implanted with the hydrophilic IOL had a greater percentage area and severity of PCO compared with patients with the hydrophobic IOL (p < 0.001). There was no difference in PCO between men and women in the hydrophilic group. However, in the hydrophobic group, women had significantly more PCO than men (p < 0.05). Patients with the hydrophobic acrylic IOL had better high- and low-contrast visual activity (VA) (p < 0.01) and less glare (p < 0.001) than those with a hydrophilic acrylic IOL. Of the patients with the hydrophilic IOL, 42% underwent capsulotomy, compared with 10% in the hydrophobic group (p < 0.001).

CONCLUSIONS

Two years after surgery, patients with the SA60AT hydrophobic acrylic IOL had less PCO and better high- and low-contrast VA than patients with the BL27 hydrophilic acrylic IOL.

Uveal and capsular biocompatibility of two foldable acrylic intraocular lenses in patients with endogenous uveitis--a prospective randomized study

BACKGROUND

To compare a hydrophobic and a hydrophilic acrylic single-piece intraocular lens (IOL) in uveitis patients with respect to biocompatibility and visual outcome.

METHODS

Prospective, randomized study in patients with noninfectious uveitis after phacoemulsification and implantation of either a hydrophobic AcrySof (group 1, n = 30) or a hydrophilic Akreos adapt (group 2, n = 30), sharp-edged acrylic IOL. The primary outcome was uveal biocompatibility, detected by giant-cell deposition, anterior chamber cell count and laserflare photometry over a 6-month follow-up period. Secondary outcome measures were capsular biocompatibility, as detected by posterior capsule opacification (PCO), lens epithelial cell outgrowth and Nd:YAG capsulotomies, and visual outcome.

RESULTS

The groups did not differ with respect to anatomic type of uveitis, immunosuppressive treatment, associated systemic disease, and intraoperative manipulation. The number of giant cells on the anterior IOL surface was higher in group 1 than in group 2 (p = 0.03). The number of anterior chamber cells, laser flare photometry levels, and uveitis reactivations after surgery did not differ between the groups. After 6 months, the number of patients with PCO development (p = 1.0) and Nd:YAG capsulotomies (p = 0.21), lens epithelial cell outgrowth, visual outcome and uveitis complications were comparable in both groups.

CONCLUSIONS

Both of the acrylic IOLs used had good uveal and capsular biocompatibility, leading to significant improvement in BCVA in patients with noninfectious uveitis. No obvious differences were detected at 6 months with respect to uveal and capsular biocompatibility and visual outcome.

Biocompatibility of intraocular lens materials

PURPOSE OF REVIEW

To provide an update on currently available materials used in the manufacture of intraocular lenses, as well as new materials under development, especially with regard to their uveal and capsular biocompatibility.

RECENT FINDINGS

The biocompatibility of intraocular lens materials should be assessed in terms of uveal biocompatibility, related to the inflammatory foreign-body reaction of the eye against the implant, as well as in terms of capsular biocompatibility, determined by the relationship of the intraocular lens with remaining lens epithelial cells within the capsular bag. This situation may result in different entities, e.g. anterior capsule opacification, interlenticular opacification (between piggyback intraocular lenses), posterior capsule opacification and lens epithelial cell ongrowth. Reports on intraocular lens opacification suggest that the potential to calcify should also be taken into consideration when evaluating the long-term biocompatibility of a new material.

SUMMARY

Intraocular lenses are being progressively implanted in much earlier stages of life (refractive lens exchange, pediatric implantation) and are expected to remain in the intraocular environment for many decades. Materials used in intraocular lens manufacture should, therefore, insure long-term uveal and capsular biocompatibility, as well as ultimate transparency after implantation.

Uveal and capsular biocompatibility after implantation of sharp-edged hydrophilic acrylic, hydrophobic acrylic, and silicone intraocular lenses in eyes with pseudoexfoliation syndrome

PURPOSE

To evaluate the uveal and capsular biocompatibility of 3 types of sharp-edged foldable intraocular lenses (IOLs) in eyes with pseudoexfoliation syndrome (PEX).

SETTING

Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

METHODS

Eighty-five eyes with PEX had implantation of 1 of the following sharp-edged 3-piece IOLs: hydrophilic acrylic (Injectacryl F3000, OphthalMed), hydrophobic acrylic (AcrySof MA60MB, Alcon), or silicone (CeeOn 911, AMO). Postoperative evaluation (flare, cellular reaction, and capsular reaction) was performed at 1, 3, and 7 days as well as 1, 3, 6, and 12 to 18 months.

RESULTS

One year after surgery, flare was comparable between the IOLs. In terms of uveal biocompatibility, whereas the Injectacryl had the highest deposition of debris on the IOL surface (P = .04), the CeeOn 911 had significantly more small round cells in the first 6 months (P<.03). The AcrySof had the highest number of foreign-body giant cells (P = .01). In terms of capsular biocompatibility, lens epithelial cell outgrowth was highest in the AcrySof group (P<.02). Anterior capsule opacification was comparable between the 3 groups. Posterior capsule opacification was mild in all groups but was significantly greater in the Injectacryl group (P<.05). There were no cases of clinically significant IOL decentration or capsule contraction.

CONCLUSIONS

In general, inflammatory cells accumulated more easily on hydrophobic IOLs than on hydrophilic IOLs; the AcrySof IOL had the highest prevalence of foreign-body giant cells. All 3 IOLs had good biocompatibility, although the AcrySof group had increased inflammatory signs.

Contact inhibition of migrating lens epithelial cells at the capsular bend created by a sharp-edged intraocular lens after cataract surgery

PURPOSE

To investigate whether the lens epithelial cells (LECs) at the capsular bend created by a sharp-edged intraocular lens (IOL) are in the G(0) phase of the cell cycle.

SETTING

Nishi Eye Hospital, Osaka, Japan.

METHOD

A CeeOn Edge silicone IOL (AMO) with sharp edges was implanted in 1 eye and a PhacoFlex II silicone IOL (AMO) with rounded edges in the contralateral eye after standard cataract surgery in 6 rabbits. Immunohistochemical staining for the Ki-67 antibody was performed 1 day, 3, 4, and 7 weeks after surgery.

RESULTS

In eyes with the sharp-edged IOL, LECs with thin, elongated nuclei accumulated at, but did not extend beyond, the capsular bend and stained negative for the Ki-67 antibody, indicating that they were in the G(0) phase of the cell cycle. In contrast, in the eye with the round-edged IOL, continuous migration of a predominantly monolayer of LECs over the IOL and onto the posterior capsule occurred. These cells were Ki-67 positive, indicating that they were proliferating.

CONCLUSIONS

Lens epithelial cells at the capsular bend of sharp-edged IOLs were in the G(0) phase of the cell cycle, indicating that they were contact inhibited. These findings support the theory the sharp posterior optic edge of the IOL inhibits LEC migration, reducing formation of posterior capsule opacification. Whether these LECs can reactivate when the capsular bend is eliminated by later formation of a Soemmerring's ring requires further studies.

Posterior capsule opacification after implantation of a hydrophilic or a hydrophobic acrylic intraocular lens: one-year follow-up

PURPOSE

To evaluate the effect of hydrophilic and hydrophobic single-piece acrylic intraocular lenses (IOLs) on posterior capsule opacification (PCO) after cataract surgery.

SETTING

St. Erik's Eye Hospital, Stockholm, Sweden.

METHODS

In a prospective study, 120 patients having cataract surgery were randomized to implantation of a hydrophilic acrylic IOL (BL27, Bausch & Lomb) or a hydrophobic acrylic IOL (AcrySof SA60AT, Alcon). Surgery was performed according to a standardized protocol by 1 of 3 surgeons. Best corrected visual acuity, contrast sensitivity, glare, intraocular pressure, and flare were measured 1 week, 3 months, and 1 year after surgery. Posterior capsule opacification was assessed by digital retroillumination photography and analysis using POCOman software at 1 year. The rate of neodymium:YAG (Nd:YAG) capsulotomy for each IOL was also recorded.

RESULTS

At 1 year, the hydrophilic acrylic IOL group had a significantly greater percentage area and severity of PCO than the hydrophobic acrylic IOL group (P<.001). Two patients in the hydrophilic acrylic IOL group and 4 in the hydrophobic acrylic IOL group had an Nd:YAG capsulotomy within the first year (P>.05). Contrast sensitivity was significantly better in the hydrophilic acrylic group at 3 months (P<.05); however, at 12 months no difference between the IOLs was observed. There was no significant difference in the other measured parameters.

CONCLUSION

Patients with the hydrophilic acrylic BL27 IOL had a significantly greater percentage area and severity of PCO than those with the hydrophobic acrylic SA60AT IOL 1 year after surgery.

Quantitative Nachstarevaluierung von Acrylat- und Silikonintraokularlinsen mit scharfem Kantendesign

BACKGROUND

At the Department of Ophthalmology, Heidelberg, Germany, posterior capsule opacification (PCO) of a silicone and an acrylic intraocular lens (IOL) with a sharp optic edge design was evaluated.

PATIENTS AND METHODS

In a prospective study either the AMO ClariFlex silicone IOL or the Sensar AR40e hydrophobic acrylic IOL were implanted in 47 patients following uneventful phacoemulsification. Mean patient age was 76.2+/-7.8 (ClariFlex) and 73.4+/-12.9 years (AR40e), respectively. The mean follow-up time was 19.7+/-5.34 in the ClariFlex and 21.9+/-1.89 months in the AR40e group. PCO development was evaluated postoperatively using the EPCO 2000 analysis software (scale 0-4). Areas of interest were the total IOL optic, the central 3-mm zone as well as the capsulorhexis.

RESULTS

In both groups, all patients achieved a BCVA of 20/32 (AR40e) and 20/25 (ClariFlex), respectively. There was a very low incidence of PCO development with a mean EPCO score of 0.07+/-0.2 (ClariFlex and 0.15+/-0.2 (AR40e). Within the 3-mm zone and the capsulorhexis, there was a tendency for even lower EPCO scores in both groups. We calculated a statistically significant difference for the two lens materials for all investigated IOL areas (Wilcoxon's test, p<0.05).

CONCLUSION

Both IOLs with a sharp edge design showed good functional results, a stable position in the capsular bag as well as a low incidence of PCO development. However, the silicone IOL showed statistically significantly lower PCO scores.

Lens epithelial cell ongrowth: Comparison of 6 types of hydrophilic intraocular lens models

PURPOSE

To compare the ongrowth of lens epithelial cells (LECs) on the anterior surface of 6 different hydrophilic intraocular lenses (IOLs).

SETTING

Medical University of Vienna, Department of Ophthalmology and Optometry, Vienna, Austria.

METHODS

Six models of hydrophilic IOLs were compared in this prospective study: Visionflex A-100 (Distra Softcryl), Rayner Centerflex 570H (Rayner), Collamer CC4204BF-IOL (Staar), Injectacryl F 3000 (Distra), Hydroview H60M (Bausch & Lomb), and MemoryLens (ORC). Postoperative biomicroscopic examinations were performed 1, 3, 7, 30, 90, 180, and 365 days after surgery. Lens epithelial cells in each quadrant of the anterior capsule-free lens surface were graded. The product with the highest density and the number of quadrants with this density were used to measure LEC ongrowth.

RESULTS

The Hydroview and Visionflex IOLs showed significantly more LECs than the other IOLs starting on day 7 after surgery (P < .028). There was a statistically significant difference in LEC ongrowth on the Memory IOL compared with all other IOLs from day 30 onward (P < .001). The Rayner, Collamer and Injectacryl IOLs had the fewest LECs on the anterior surface compared with all other IOLs from day 7 until the final examination.

CONCLUSIONS

The findings show that LEC ongrowth on the IOL surface is material dependent. The findings suggest that the material of the recently developed hydrophilic IOLs induces less LEC ongrowth than older models.

Evaluation of posterior capsule opacification using a new posterior view method in rabbits

PURPOSE

To introduce a new procedure for evaluating posterior capsule opacification (PCO) in rabbit eyes and to perform a comparative study of the single-piece and 3-piece acrylic intraocular lenses (IOLs) on PCO using the new evaluation method.

SETTING

Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan.

METHODS

A single-piece or 3-piece acrylic IOL was implanted in 1 eye and the other in the contralateral eye of 5 rabbits. Three weeks after surgery, PCO was scored by Evaluation of Posterior Capsule Opacification (EPCO) in posterior view. Before the posterior view was photographed, the anterior capsule was removed from the whole optic area to eliminate disturbing anterior capsule opacification (ACO) for the PCO evaluation.

RESULTS

Posterior capsule opacification could be well observed and viewed in the posterior view so that it could be scored by EPCO without confusion with ACO. The mean PCO score of the single-piece and 3-piece acrylic IOLs was 3.12 +/- 0.19 and 2.41 +/- 0.70, respectively (P < .05 and P = .03, respectively).

CONCLUSION

The removal of ACO allowed scoring of PCO by EPCO in rabbit eyes. The single-piece acrylic IOL showed significantly more PCO than the 3-piece acrylic IOL at least 3 weeks after surgery in rabbits.

[Influence of intraocular lens material and design on the development of posterior capsule opacification]

Based on the literature of 1999-2005, we attempted to clarify the influence of material and design of an intraocular lens (IOL) on the development of posterior capsule opacification (PCO) and identify the future problems to be solved. The sharp edge design of an IOL has significantly reduced PCO in recent years. Histopathological studies showed that a sharp capsular bend was formed at the sharp posterior optic edge, and the migration of lens epithelial cells was obviously inhibited at the site. Experimental and clinical studies suggest that the sharper the edge is, the sharper the capsular bend, and the greater the preventive effect, regardless of IOL material. The sharp capsule bend appears to represent a physical hindrance, which may induce contact inhibition of cell movement. How material participates in the preventive effect should be clarified in a future study. Thus, at the moment, the formation of capsular bend at the posterior optic edge appears to be the decisive criterion to evaluate the influence of IOL material and design on the development of PCO. Optimization of design and material of an IOL, which facilitates capsular bend formation as sharply and quickly as possible, may reduce PCO to a clinically negligible level.

Centripetal lens epithelial cell migration: a prospective study of the Alcon SA60AT intraocular lens

PURPOSE

To evaluate prospectively the incidence and severity of centripetal lens epithelial cell migration (CLECM) onto the anterior surface of the Alcon SA60AT intraocular lens (IOL).

METHODS

One hundred and four consecutive cases of SA60AT IOL implantations were prospectively evaluated. At the 1-month postoperative visit, best corrected visual acuity (BCVA) was obtained. Following maximal pupillary dilatation, the extent of CLECM was assessed using a simplified grading scale (0-4). The centrality of the lens within the capsular bag was recorded. Patients with the highest grade of CLECM were recalled for reassessment at a minimum of 3 months.

RESULTS

Centripetal lens epithelial cell migration data were obtained on 99 patients. Of these, 94% demonstrated CLECM of varying severity at 1 month postoperatively. The severity was low grade in 54% of patients (29% grade 1, 24% grade 2), and high grade in 40% of patients (16% grade 3, 24% grade 4). BCVA results were good (91.9% 6/6 or better) and did not correlate with CLECM grade. Operative capsulorhexis size did not correlate with the severity of CLECM. The lens was well-centred in 91 of 92 patients in whom lens position was assessed. Twenty-three patients with grade 4 CLECM at 1 month were brought back for reassessment (3.5-13 months postoperatively) and 18 of these demonstrated complete regression of CLECM (to grade 0).

CONCLUSIONS

There is a high incidence and severity of CLECM 1 month postoperatively using the Alcon SA60AT IOL. There was no significant correlation between CLECM grade and either BCVA at 1 month, capsulorhexis size or lens centration. CLECM appears to be a frequent, benign and transient event with this lens.

Posterior capsule opacification in rabbit eyes implanted with 1-piece and 3-piece hydrophobic acrylic intraocular lenses

PURPOSE

To evaluate the outcome of posterior capsule opacification (PCO) after implantation in rabbit eyes of currently available 3-piece and 1-piece hydrophobic acrylic intraocular lenses (IOLs) with square optic edges.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

METHODS

The 3-piece designs evaluated were the AR40e (Advanced Medical Optics Inc.) and the MA60AC (Alcon, Inc.); the 1-piece designs were the SA60AT and the SA30AT (Alcon, Inc.). Nine lenses of each type were implanted in a randomized manner by the same surgeon in 18 Dutch Belted pigmented rabbits. After a follow-up of 3 weeks, the rabbits were killed and analyses of the enucleated eyes were performed from the posterior or Miyake-Apple view. The intensity of central PCO, peripheral PCO, and Soemmering's ring formation was scored from 0 to 4. The area of Soemmering's ring formation was also scored from 0 to 4 based on the number of quadrants involved. Other parameters analyzed were capsulorhexis coverage of the IOL anterior surface, IOL centration, fixation, and presence of striae. Results from the posterior view were complemented by histopathologic evaluation of the eyes.

RESULTS

No statistically significant difference was found between the 4 groups of IOLs in the parameters analyzed from the posterior view. When cell ingrowth occurred with the 1-piece designs, causing peripheral and central PCO formation, it was more likely to start at the optic-haptic junctions, as observed during the clinical follow-up with slitlamp examination and confirmed by gross and histopathologic analyses of the enucleated eyes.

CONCLUSIONS

The square, truncated optic edge is the most important IOL design feature for PCO prevention. The optic-haptic junctions of the 1-piece designs appear to be sites where the barrier effect of the truncated optic edge is less effective.

Three-year follow-up of posterior capsule opacification with two different silicone intraocular lenses

PURPOSE

To compare posterior capsule opacification (PCO) after cataract surgery with implantation of two silicone intraocular lenses (IOLs) with different designs.

METHODS

We carried out a prospective, clinical study of 116 patients randomized to standardized phacoemulsification with implantation of CeeOn Edge (n = 57) or SI40NB (n = 59) IOLs. The follow-up period was 3 years. To evaluate PCO morphologically, digital images were obtained and analysed using evaluation of posterior capsule opacification computer software (epco). The neodymium:YAG (Nd:YAG) capsulotomy rate was recorded.

RESULTS

At 2 and 3 years, the eyes with SI40NB IOLs had significantly more PCO than those with the CeeOn Edge IOLs (p = 0.00014 and p = 0.002). Nine Nd:YAG capsulotomies were performed in the SI40NB group and none in the CeeOn Edge group. This difference was statistically significant (p = 0.003). In some patients a regression of PCO was noticed and confirmed using epco. Statistically less PCO was noted when the capsulorhexis rim was placed so that it covered all 360 degrees of the optic of the IOL.

CONCLUSIONS

A clinically and statistically significant difference in PCO development between CeeOn Edge and SI40NB IOLs at 2 and 3 years postoperatively was found. These findings support earlier studies indicating that a sharp edge of the optic is a more important factor in IOL design than IOL material in the prevention of PCO.

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

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

Effect of intraocular lenses on preventing posterior capsule opacification: design versus material

PURPOSE

To compare the preventive effect of 4 types of design- and material-matched intraocular lenses (IOLs) on posterior capsule opacification (PCO).

SETTING

Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan.

METHODS

After phacoemulsification, 1 of 2 matched IOLs in 3 groups was implanted in 1 eye and the other IOL in the contralateral eye of 4 to 6 rabbits. Three weeks postoperatively, posterior view and histopathological evaluations were performed and the capsular bending effect and amount of PCO evaluated.

RESULTS

The capsular bending effect was similar between a sharp-edged acrylic IOL (Sensar 40e, AMO) and a sharp-edged silicone IOL (ClariFlex, AMO) and between the Sensar 40e IOL and a sharp-edged acrylic IOL (AcrySof, Alcon Laboratories). There was no significant difference between IOL types in the amount of PCO. The capsular bend effect was slightly better and the PCO amount slightly less with the ClariFlex IOL than with the round-edged silicone PhacoFlex II IOL (AMO).

CONCLUSIONS

There was no substantial difference in PCO prevention between IOLs with sharp posterior optic edges, regardless of the IOL's material composition. The anterior edge design appeared to have no preventive effect. These results confirm that a sharp posterior optic edge is the main factor in preventing PCO.

Posterior capsule opacification in rabbit eyes implanted with hydrophilic acrylic intraocular lenses with enhanced square edge

PURPOSE

To evaluate the development of posterior capsule opacification (PCO) after implantation of single-piece hydrophilic acrylic intraocular lenses (IOLs) with an enhanced square edge.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

METHODS

The standard 570H Centerflex (Rayner Ltd.) design was compared to 2 new designs with enhanced square edges: the 570E and the 570C. Ten IOLs of each type were implanted in a randomized manner by the same surgeon in 15 pigmented rabbits. After a follow-up of 3 weeks, the rabbits were killed and the eyes were analyzed from the posterior view. The intensity of central PCO, peripheral PCO, and Soemmering's ring formation was graded from 0 to 4. The area of Soemmering's ring was graded from 0 to 4 based on the number of quadrants involved. Other parameters analyzed were capsulorhexis coverage of the IOL edge and IOL centration and fixation. Results from the posterior view were complemented by histopathological evaluation.

RESULTS

Posterior capsule opacification was lowest in the 570C group, highest in the 570H group, and intermediate in the 570E group. There was a statistically significant difference between the 3 groups in peripheral PCO (P = .039). No significant difference was found between the groups in the other parameters analyzed. When cell ingrowth occurred with the 570H, it started at the optic-haptic junctions, as observed during the clinical follow-up and confirmed by gross and histopathological analyses.

CONCLUSIONS

The square optic edge is the most important IOL design feature for PCO prevention. However, it should be present for 360 degrees around the IOL optic to provide an effective barrier effect.

The effect of lens edge design versus anterior capsule overlap on posterior capsule opacification

PURPOSE

To determine whether lens edge design or anterior capsule overlap on the intraocular lens (IOL) has greater effect on posterior capsule opacification (PCO).

DESIGN

Retrospective cohort clinical study.

METHODS

Retrospective.

SETTING

Academic clinical practice.

PATIENT POPULATION

The patient population consisted of 259 uncomplicated surgical patients (259 eyes) with no confounding comorbidity and at least 1 year of follow-up after surgical placement of a silicone or hydrophobic acrylic lens.

OBSERVATION PROCEDURES

Digital retroilluminated photographs were taken to ascertain PCO, anterior capsular opacification (ACO), previous neodymium:YAG capsulotomy and degree of anterior capsule overlap on the IOL optic.

MAIN OUTCOME MEASURES

PCO, ACO, YAG capsulotomy rate, and anterior capsule overlap on the IOL optic.

RESULTS

One hundred forty-eight digital images (74 silicone and 74 acrylic) were measurable for both anterior capsule overlap and PCO. Complete 360 degrees of anterior capsule overlap on the IOL was associated with decreased PCO (P = <.001). A significant negative correlation was found between the degree of anterior capsule overlap and PCO (P = <.001). Evaluation of PCO, and YAG capsulotomy rates were similar between acrylic and silicone lenses. Minimal anterior capsule overlap may also be associated with PCO prevention.

CONCLUSIONS

Implanting a lens with complete anterior capsule overlap on the IOL was found to significantly reduce PCO, which advantage appeared to be greater than PCO prevention by a truncated, sharp edge IOL design.

Uveal and capsular biocompatibility of a single-piece, sharp-edged hydrophilic acrylic intraocular lens with collagen (Collamer): 1-year results

PURPOSE

To analyze uveal and capsular biocompatibility 1 year following implantation of a sharp-edged, hydrophilic, collagen-containing posterior chamber intraocular lens (IOL).

SETTING

Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria.

METHOD

In a prospective study, a Collamer CC4204BF IOL was implanted in 30 eyes of patients with senile cataract. A standardized surgical technique and postoperative regimen were applied. To assess uveal biocompatibility, cellular inflammation on the anterior IOL surface was evaluated with a specular microscope. Capsular biocompatibility was registered semiquantitatively with a biomicroscope, based on an assessment of fibrosis on the anterior and posterior capsules. Tyndall values were measured with the Kowa FC-1000 laser flare-cell meter. Decentration of the lens was also registered.

RESULTS

One year after implantation, the values of flare and cell count in the anterior chamber were lower than preoperatively. Round and spindle-shaped, epithelioid, and foreign-body giant cells were not found on the anterior surface of the IOL. The capsulorhexis rim was moderately fibrosed in 56.6% of cases. Fibrosis of the capsule over the optic was also moderate in 36.6%. The central portion of the posterior capsule was devoid of fibrosis in 43.3% and mildly fibrosed in 50%. Three lenses revealed outgrowth of lens epithelial cells to the anterior surface of the IOL. A neodymium:YAG capsulotomy had to be performed in 1 case. All lenses were well centered in the capsular bag 1 year after implantation.

CONCLUSIONS

The absence of inflammatory cells on the anterior surface of the IOL indicates the high uveal biocompatibility of the lens. In terms of capsular biocompatibility, the results were satisfactory.

Pathological evaluation of postmortem human eyes implanted with a new single-piece hydrophobic acrylic lens

PURPOSE

To report the pathological findings in 14 human cadaver eyes implanted with a single-piece AcrySof(Alcon Laboratories) posterior chamber intraocular lens (IOL).

SETTING

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

METHODS

Fourteen human autopsy eyes implanted with a single-piece AcrySof (SA30AL) IOL were evaluated. The eyes were sectioned at the equatorial plane, and the anterior segment containing the IOL in the capsular bag was evaluated from a posterior perspective (Miyake-Apple view) and from an anterior perspective (surgeon's view) after removal of cornea and iris. They were then processed through paraffin, sectioned, and stained with hematoxylin-eosin, periodic acid-Schiff, and Masson's trichrome and examined under light microscopy.

RESULTS

All IOLs had symmetric in-the-bag fixation. Slight decentration was measured in 1 eye, which also had an anterior capsule tear. Grade 1 anterior capsule opacification was present in 9 eyes. No central posterior capsule opacification or posterior capsule folds were observed in any eye. Soemmering's ring formation was observed in 5 eyes. Zonular stretch caused by different degrees of capsular bag contraction was present in 4 eyes without decentration of the IOL.

CONCLUSIONS

Analyses of pseudophakic cadaver eyes from the posterior (Miyake-Apple) view, complemented by microscopic analyses, proved useful in the evaluation of IOL-capsular bag interaction. These studies are more important in cases of newly introduced lens designs.

Neodymium:YAG laser posterior capsulotomy after implantation of AcrySof intraocular lenses

PURPOSE

To report the incidence of neodymium:YAG (Nd:YAG) laser posterior capsulotomy after phacoemulsification and implantation of AcrySof (Alcon) intraocular lenses (IOLs).

SETTING

Private practice, Wolfe Clinic, Marshalltown, Iowa, USA.

METHODS

A retrospective diagnosis and procedure code review of 12419 consecutive cases having phacoemulsification and AcrySof IOL implantation from January 1995 through December 2002 was performed. The outcome parameter was the incidence of Nd:YAG laser posterior capsulotomies.

RESULTS

An Nd:YAG laser posterior capsulotomy was performed in 763 (6.1%) of the 12419 cases. The incidence of posterior capsulotomy was approximately 1% at 1 year, increasing in linear fashion by approximately 1% to 2% per year.

CONCLUSIONS

The Nd:YAG laser posterior capsulotomy rate after implantation of AcrySof IOLs was relatively low; the cumulative rate was approximately 1% to 2% new cases per year over a 7-year period, with a plateau suggested at year 6.

Relationship between posterior capsule opacification and intraocular lens biocompatibility

The type of healing process that occurs in response to cataract surgery and intraocular lens (IOL) implantation is dependent on a complex set of variables. Their interactions determine whether or not optical clarity is restored as a result of this procedure. In this process, wound healing entails cells undergoing either epithelial-mesenchymal transition, resulting in the generation of fibroblastic cells and accumulation of extracellular matrix, or lenticular structure formation. Such desperate cellular behaviors are regulated by the localized release of different cytokines, including transforming growth factor beta and fibroblast growth factors, which can result in post-operative capsular opacification. Other factors affecting the biological and mechanical outcome of IOL implantation are its composition, surface properties and shape.

Posterior capsule opacification after implantation of CeeOn Edge 911A, PhacoFlex SI-40NB, and AcrySof MA60BM lenses

PURPOSE

To perform an intraindividual comparison of posterior capsule opacification (PCO) with 2 foldable intraocular lenses (IOLs) and a foldable acrylic IOL 1 year after in-the-bag implantation.

SETTINGS

Seven German ophthalmology centers.

METHODS

In an open prospective randomized multicenter study, each center intraindividually compared a high-refractive-index, sharp-edged optic silicone IOL (CeeOn Edge 911A, Pharmacia) with a high-refractive-index, round-edged optic silicone IOL (PhacoFlex SI-40NB, Allergan) or a sharp-edged optic acrylic IOL (AcrySof MA60BM, Alcon). Of 288 randomized patients, 247 had standard phacoemulsification with in-the-bag IOL implantation in both eyes by the same surgeon. One eye of each patient received a CeeOn Edge IOL and the fellow eye, an AcrySof or PhacoFlex IOL. A morphologic evaluation of PCO was performed using the Evaluation of Posterior Capsule Opacification (EPCO) system 1 to 2 weeks and 11 to 14 months after surgery. The digital pictures were evaluated by an independent investigator who was blind to the type of IOL. Intraindividual differences in EPCO scores were statistically evaluated by a 1-sided binomial test at an alpha-level of 5%.

RESULTS

One year after surgery, 127 patients with the AcrySof IOL and 102 patients with the PhacoFlex IOL in the control eye were reexamined. Functional results, safety, and handling were not significantly different between the 3 IOLs. All reexamined eyes had a very low PCO grade. The EPCO values revealed less PCO in eyes with the CeeOn Edge IOL than in eyes with the AcrySof or PhacoFlex IOL, but the difference was not statistically significant. A neodymium:YAG laser capsulotomy was performed in 1 eye with a CeeOn Edge IOL, 1 eye with an AcrySof IOL, and 2 eyes with a PhacoFlex IOL.

CONCLUSIONS

The EPCO PCO grade was low 1 year after implantation of CeeOn Edge 911A, PhacoFlex SI-40NB, and AcrySof MA60BM IOLs; there was no statistically significant difference between the IOLs. The impact of IOL material and edge design on PCO development might be relevant in a long-term follow-up of this study.

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.

A clinical comparison of single-piece and three-piece truncated hydrophobic acrylic intraocular lenses

PURPOSE

To determine the clinical differences between three-piece (3P) and single-piece (SP) truncated hydrophobic acrylic intraocular lenses (IOL).

DESIGN

Retrospective cohort clinical study.

METHODS

The setting was an academic clinical practice. The patient population consisted of subjects without confounding comorbidity that could effect central vision with at least 1-year follow-up after uncomplicated surgical placement of 3P or SP IOLs in the capsular bag and at least 20/25 best-corrected postoperative vision documented. Observation procedures were as follows: logarithm of the minimal angle of resolution (LogMAR) visual acuity (uncorrected and best corrected), digital retroillumination photographs to ascertain posterior capsular opacification (PCO), anterior capsular opacification (ACO), IOL centration, and refractive stability by comparing this refraction with the early postoperative refraction. Patients completed a dysphotopsia questionnaire. Main outcome measures were as follows: LogMAR visual acuity (uncorrected and best corrected), PCO, ACO, IOL centration, refractive stability, and dysphotopsia outcomes comparing 3P and SP.

RESULTS

Seventy-five patients were enrolled (36 3P and 39 SP). Corrected and uncorrected visual acuity, refractive stability, and IOL centration were similar. Single piece truncated hydrophobic acrylic intraocular lenses had more PCO (P =.013), less ACO (P =.001), less central flash looking at a peripheral light (P =.044), and less unwanted images to the side of a light source (P =.025) .

CONCLUSIONS

Although similar in centration and refractive stability, SP has more PCO, less ACO, and less dysphotopsia than 3P.

Lens epithelial cell reaction after implantation of different intraocular lens materials

PURPOSE

To determine the influence of intraocular lens (IOL) material on anterior capsular opacification and membrane growth over the anterior IOL surface in patients who have undergone standardized small-incision cataract surgery and foldable IOL implantation in the capsular bag.

DESIGN

Randomized controlled trial.

PARTICIPANTS

Eighty-eight cataract patients (88 eyes).

METHODS

Patients were randomly assigned to receive one of four different foldable IOLs after phacoemulsification: Storz Hydroview H60M, Corneal ACR6D, AMO SI40NB, and Alcon AcrySof MA60BM. Examinations on days 7, 30, 90, 180, 360, and 720 after surgery included ophthalmologic examination, slit-lamp biomicroscopy, and photography using red reflex and focal illumination of the anterior IOL surface.

MAIN OUTCOME MEASURES

Best-corrected visual acuity was measured at each examination. In addition, the anterior capsule opacification and the membrane growth on the anterior IOL surface were graded according to a subjective method by the same researcher.

RESULTS

The fibrosis of the anterior capsule was more frequently observed in the group using Corneal ACR6D and AMO SI40NB. The Hydroview and ACR6D groups showed a higher percentage of cases with membrane growth from the rhexis edge on the anterior IOL surface. AcrySof showed the lowest presence of fibrosis of the anterior capsule, and no membrane growth was noted.

CONCLUSIONS

Anterior capsule opacification is an index of IOL biocompatibility. The natural location of lens epithelial cells (LECs) precludes the possibility of the IOL's design influencing the anterior capsule behavior. The local response of LECs varies according to the IOL studied. This may be related to the chemical and physical properties of the materials used in the different IOLs.

Capsulotomy diameter mark

Recent improvements in intraocular lens (IOL) design and material delay posterior capsule opacification (PCO) after cataract surgery. However, studies have shown that without anterior capsule coverage of the IOL, PCO rates tend to increase. Surgeons have traditionally sized anterior capsulotomies without using a reference. The capsulotomy diameter mark is a convenient and inexpensive method to more consistently perform an anterior capsulorhexis that will allow anterior capsule overlap of the IOL optic.

Posterior capsule opacification: silicone plate-haptic versus AcrySof intraocular lenses

PURPOSE

To evaluate posterior capsule opacification (PCO) in fellow eyes, 1 receiving a silicone intraocular lens (IOL) and the other, an acrylate IOL.

SETTING

Department of Ophthalmology, Isala Clinics, Zwolle, The Netherlands.

METHODS

This retrospective study comprised 107 patients (214 eyes). In each patient, 1 eye was randomly selected to have implantation of an acrylate IOL (AcrySof MA30BA or MA60BM, Alcon) and the other eye, a plate-haptic silicone IOL (AA4203VF, Staar). Outcome measures were the total PCO index, percentage of neodymium:YAG (Nd:YAG) capsulotomies performed, and logMAR best corrected visual acuity (BCVA). The follow-up was 3 years.

RESULTS

The total PCO index was significantly lower in the AcrySof group than in the plate-haptic silicone group (P<.0001). There was no significant difference in logMAR BCVA between groups (P>.05). The percentage of Nd:YAG laser treatments was significantly lower in the AcrySof group (2.8%) than in the plate-haptic silicone group (23.1%) (P<.05).

CONCLUSIONS

There was significantly less PCO and a lower Nd:YAG laser capsulotomy rate after AcrySof IOL implantation than after plate-haptic silicone IOL implantation. These results did not seem to affect the logMAR BCVA as there were no significant differences between groups in this parameter.

Biocompatibility of intraocular lenses

PURPOSE

The choice of intraocular lens (IOL) implanted by cataract surgeons has significant implications for the effectiveness of the operation and the subsequent need for capsulotomy.

METHODS

Comparison of pertinent peer-reviewed literature published from 1996 through 2001 obtained from a MEDLINE literature search on biocompatibility indicators and IOLs. This review pertains to routine, uncomplicated cataract surgery, and thus, the findings may not be relative to complicated surgeries. Currently available IOLs were not included in this review if no published data on the IOL were available. However, representative lenses from all the major biomaterial classes were included.

RESULTS

Overall results of a comparison of published accounts of posterior capsular opacification, Nd:YAG capsulotomies, anterior capsular opacification, aqueous flare, cellular reaction, capsular adhesion, and capsular stability show a polyacrylic elastomer to be the most highly biointegrated IOLs by the human eye.

CONCLUSIONS

Most evidence published in peer-reviewed journals suggests a clear IOL choice for cataract surgeons. In the field of implantable medical devices, one device in a category does not usually provide consistently superior performance of its intended function. The ability of the biomaterial to maintain a clear optical axis not only by suppressing the proliferation of lens epithelial cells, and thus inhibiting posterior capsular opacification formation and obviating the need for an Nd:YAG capsulotomy, but also by adhering to and stabilizing the capsular bag is, to date, unmatched by any other IOL available.

Cataract treatment in the beginning of the 21st century

PURPOSE

To describe the principles upon which present day cataract treatment success resides.

DESIGN

Literature review and collective experience of the authors.

RESULTS

Surgical removal remains the standard treatment for cataract now and in the foreseeable future. Ultrasound cataract removal with a foldable "in-the-bag" intraocular lens with a truncated edge treated for dysphotopsia best correlates with core treatment principles, as we now understand them. Improving refractive results is an important trend. The worldwide burden of this problem is immense.

CONCLUSIONS

While results for treatment of cataracts are excellent today, improvements in safety and refraction precision are needed. Other approaches are desperately needed to stem the worldwide tide of cataract related ocular dysfunction.