Anterior capsule opacification: a histopathological study comparing different IOL styles

Loop memory of haptic materials in posterior chamber intraocular lenses

PURPOSE

To compare the shape recovery ratios after compression of haptic materials used in the manufacture of intraocular lenses (IOLs).

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

The loop memory of 40 silicone-optic posterior chamber IOLs was studied. All the IOLs had modified-C haptics made of poly(methyl methacrylate) (PMMA; n = 10), polyimide (n = 10), polyvinylidene fluoride (PVDF; n = 10), and polypropylene (PP; n = 10). After the overall diameter of each lens was measured (day 0), the lenses were inserted into plastic wells (9.5 mm in diameter) and immersed in water (37 degrees C) for 1 month. They were then placed on an open plate and allowed to reexpand for 2 months. Overall diameter measurements were performed within 5 minutes of the IOLs' removal from the wells and at subsequent time points (days 14, 28, 30, 60, 74, 88, and 95).

RESULTS

The loop memory of each lens was expressed as the difference between the initial overall diameter measurement (pretest) and the measurement at each time point; the lower the value, the higher the memory. The overall difference among the 4 groups was statistically significant at each time point (P < or = .001). From days 30 to 95, silicone-PMMA, silicone-elastimide, and silicone-PVDF IOLs had similar loop memory mean values, which were significantly lower than the mean value of silicone-PP IOLs (P <.05). The latter design tended to be deformed after removal from the wells, with increased optic-haptic angulation.

CONCLUSION

Studying the loop memory of haptic materials (PMMA, polyimide, PVDF, and PP) used in the manufacture of posterior chamber IOLs can help surgeons choose an appropriate IOL for each patient.

Results of hydrophilic acrylic, hydrophobic acrylic, and silicone intraocular lenses in uveitic eyes with cataract: comparison to a control group

PURPOSE

To evaluate the uveal and capsular biocompatibility of hydrophilic acrylic, hydrophobic acrylic, and silicone intraocular lenses (IOLs) in eyes with uveitis.

SETTING

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

METHODS

This prospective study comprised 72 eyes with uveitis and 68 control eyes having phacoemulsification and IOL implantation by 1 surgeon. Patients received 1 of the following IOLs: foldable hydrophilic acrylic (Hydroview, Bausch & Lomb), hydrophobic acrylic (AcrySof, Alcon), or silicone (CeeOn 911, Pharmacia). Postoperative evaluations were at 1, 3, and 7 days and 1, 3, and 6 months. Cell reaction was evaluated by specular microscopy of the anterior IOL surface and the anterior and posterior capsule reaction, by biomicroscopy.

RESULTS

Small round cell deposition was observed on all IOLs in the immediate postoperative period, especially in eyes with uveitis. This reaction decreased 3 to 6 months after surgery. Although the CeeOn 911 had a higher mean grade of small cells, there was no statistical difference between the 3 IOL types after 6 months in the uveitis and control groups. Foreign-body giant cells (FBGCs) increased after 1 week to 1 month. The AcrySof IOLs had the highest number of FBGCs; after 6 months, there was a statistically significant difference between the AcrySof and Hydroview uveitis groups (P =.036) and the AcrySof and CeeOn 911 uveitis groups (P =.003) but there was no difference among the 3 IOL types in the control group. Lens epithelial cell outgrowth persisted on the Hydroview IOLs in control eyes and regressed on all 3 IOL types in uveitic eyes and on the AcrySof and CeeOn 911 IOLs in control eyes (P =.0001). Anterior capsule opacification (ACO) was more severe on all IOL types in uveitic eyes and on the CeeOn 911 IOL in control eyes. Posterior capsule opacification (PCO) was more severe in uveitic eyes. The Hydroview group had more severe PCO than the AcrySof and the CeeOn 911 groups in uveitis and control eyes. Six months postoperatively, the difference was significant (P =.0001). There was no significant difference between the AcrySof and CeeOn 911 IOLs.

CONCLUSIONS

Intraocular lens biocompatibility is inversely related to inflammation. Hydrophilic acrylic material had good uveal but worse capsular biocompatibility. Hydrophobic acrylic material had lower uveal but better capsular biocompatibility. Silicone showed a higher small cell count (mild) and more severe ACO but achieved PCO results comparable to FBGC results and better than those with the AcrySof lens 6 months after surgery. Despite the differences in IOL biocompatibility, all patients benefited from the surgery.

Three-year clinical comparison of 3-piece AcrySof and SI-40 silicone intraocular lenses

PURPOSE

To compare the 3-year performance of the 3-piece AcrySof (Alcon) and the SI-40 silicone (Allergan) intraocular lenses (IOLs).

SETTING

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

METHODS

In this retrospective study, patients with no complications and at least a 3-year follow-up after IOL implantation were examined for signs of inflammation, visual function, posterior capsule opacification (PCO), and satisfaction.

RESULTS

One hundred eleven patients were enrolled with equivalent visual acuity, inflammation, and PCO parameters. The AcrySof eyes had less anterior capsule opacification and more intralenticular inclusions than the other group. Complete anterior capsule overlap was associated with decreased PCO, and significantly more SI-40 eyes had complete anterior capsule overlap.

CONCLUSIONS

The second-generation silicone IOL was equivalent to the 3-piece AcrySof in patient satisfaction, visual function, inflammation, and PCO. The amount of anterior capsule overlap on the IOL may help to explain the study differences.

The influence of implant design on accuracy of postoperative refraction

PURPOSE

To assess the degree of accuracy of postoperative refraction that may be achieved with modern techniques and a new lens of modern design.

METHODS

Five hundred eyes underwent refraction at one week and one month following phacoemulsification and implantation of the Centerflex lens (Rayner Intraocular Lenses Ltd style 570H). Results were compared with the target that had been computerised at the time of surgery, using the Hoffer Q formula for axial lengths less than 22.0 mm, the SRK-T for lengths greater than 24.5 mm and a mean of the two formulae for lengths between 22.0 and 24.5 mm. Statistical analysis used Fisher's exact and one way ANOVA tests.

RESULTS

At one month 97% of refractions were within 1.0 D spherical equivalent (SE) of target and 81% within 0.5 SE. The mean absolute error was 0.37 +/- 0.39 SD. 75.8% of all eyes achieved 6/12 unaided and 88.6% achieved 6/9 with correction. In only 1.2% the refraction between one week and one month had altered by 0.5 D or more.

CONCLUSIONS

The Centerflex when combined with modern methods of power calculation, can be associated with a high degree of accuracy in postoperative refraction.

Post cataract-intraocular lens (IOL) surgery opacification

Intraocular lens (IOL) implantation has no doubt been one of the most satisfying advances of medicine. Millions of individuals with visual disability or frank blindness from cataracts had and continue to have benefit from this procedure. It has been reported by ophthalmologists that the modern cataract-intraocular lens (IOL) surgery is safe and complication-free most of the time. This makes the watchword for any cataract surgeon to be 'implantation,' 'implantation,' 'implantation.' In the mid-1980s, as IOLs were evolving rapidly, the watchword of the implant surgeon was 'fixation,' 'fixation,' 'fixation.' Most techniques, lenses and surgical adjuncts now allow us to achieve the basic requirement for successful IOL implantation, namely long-term stable IOL fixation in the capsular bag. However despite this advancement some items 'slipped through cracks.' In this article, we would like to alert the reader to a new watchword, namely 'opacification,' 'opacification,' 'opacification.' Here we will be talking about the good, the bad, and the ugly. Examples of the 'good' include the recent successes now being achieved in reducing the incidence of posterior capsule opacification. Examples of the 'bad' include various proliferations of anterior capsule cells, problems caused by silicone oil adherence to IOLs and problems with piggyback IOLs. The 'ugly' include the sometimes striking and often visually disabling opacifications occurring on and within IOL optics, both on some modern foldable IOLs as well as a poly(methyl methacrylate) (PMMA) optic degradation occurring with some models a decade or more after implantation.

Biocompatibility of hydrophilic intraocular lenses

PURPOSE

To assess the biocompatibility of 3 hydrophilic acrylic intraocular lenses (IOLs) by evaluating the postoperative cell reaction on the IOL surface, anterior capsule opacification (ACO) rate, and presence of membrane growth over the anterior IOL surface.

SETTING

University Eye Clinic of Trieste, Trieste, Italy.

METHODS

In this prospective study, 73 patients were randomized to receive 1 of 3 types of hydrogel IOLs after phacoemulsification: Storz Hydroview H60M, Corneal ACR6D, or Ioltech Stabibag. To analyze and photograph the anterior IOL surface, slitlamp biomicroscopy and specular microscopy were performed 7, 30, 90, and 180 days after surgery. Small, epithelioid, and giant inflammatory cell reaction was evaluated. In addition, ACO and membrane growth on the anterior IOL surface were assessed.

RESULTS

Low inflammatory cell adhesion was observed on the anterior surface of all 3 IOLs. The Stabibag group had a significantly higher grade of small inflammatory cell reaction 7 and 30 days after surgery. A significantly higher rate of ACO was observed in the ACR6D group. The Hydroview and ACR6D groups had a significantly higher percentage of membrane growth from the capsulorhexis edge onto the anterior IOL surface than the Stabibag group.

CONCLUSIONS

Clinically, the 3 hydrophilic IOLs behaved in a different manner, showing the different forms of biocompatibility. Results indicate that a different chemical composition determines correspondingly different protein absorption on IOL surfaces. This might result in a different adhesion pattern and spreading of lens epithelial and inflammatory cells.

Survey of intraocular lens material and design

Modern cataract surgery is constantly evolving and improving in terms of lens material and design. Researchers and physicians strive to obtain better refractive correction with smaller wound size and minimizing host cell response to limit the proliferation of lens epithelial cells leading to opacification of the lens capsule. Intraocular lens material varies in water content, refractive index, and tensile strength. Intraocular lens design has undergone revisions to prohibit lens epithelial cell migration and reflection of internal and external light. The evolution of intraocular lens and extracapsular cataract surgery has lead to faster postoperative recovery and better visual outcomes.

Intracapsular ring sustained 5-fluorouracil delivery system for the prevention of posterior capsule opacification in rabbits: a histological study

PURPOSE

To evaluate the efficacy of an intracapsular ring releasing 5-fluorouracil (5-FU) in preventing posterior capsule opacification (PCO) in rabbit eyes.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA, and Chu Morvan, Department d'Ophtalmologie, University of Brest, France.

METHODS

Seventeen rabbits were divided into 3 groups: Group 1, 6 rabbits (6 eyes), had phacoemulsification only (control group); Group 2, 6 rabbits (6 eyes), had phacoemulsification with implantation of an open-loop hydrogel intracapsular ring; Group 3, 5 rabbits (5 eyes), had phacoemulsification with implantation of a ring with sustained release of 0.25 microg/h of 5-FU for 9 days. All eyes were followed for 8 weeks before enucleation. Capsular bag shrinkage and the position of the intracapsular ring were assessed, and central and peripheral PCO was evaluated for intensity and area by stereomicroscopy from a posterior (Miyake-Apple) view. The residual equatorial lens epithelial cells (LECs) were counted by the same observer in histological sections. Transmission electron microscopy (TEM) of the cornea, capsular bag, and retina was done to evaluate the toxicity of 5-FU.

RESULTS

No significant difference was seen in the degree of capsular bag shrinkage in the 3 groups. The intracapsular ring was decentered in 2 eyes (1 each in Groups 2 and 3). There was a statistically significant difference (P <.05, Student t test) between Group 1 and Groups 2 and 3 in the area and intensity of central PCO. There was no difference between Groups 2 and 3 in the intensity of central PCO. No evidence of 5-FU toxicity to intraocular structures (cornea, capsular bag, and retina) was demonstrated on TEM analysis.

CONCLUSION

Implantation of an intracapsular ring may prevent central PCO after cataract surgery by mechanically blocking LEC migration toward the central visual axis. The potential pharmacological effect of 5-FU in PCO prevention was not demonstrated.

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

PURPOSE

To evaluate the long-term response of 6 types of 3-piece intraocular lenses (IOLs) by assessing the cellular reaction on the anterior IOL surface, the behavior of posterior and anterior capsule fibrosis, and flare.

SETTING

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

METHODS

One hundred eighty eyes were prospectively randomized to receive 1 of 6 IOLs: hydrophilic acrylic Hydroview (Bausch & Lomb) or MemoryLens (ORC); hydrophobic acrylic AcrySof MA60BM (Alcon) or AMO Sensar AR40 (Allergan); hydrophobic silicone CeeOn 920 or CeeOn 911A (Pharmacia). The patients had standardized cataract surgery, postoperative medication, and follow-up. One year after surgery, 155 eyes were assessed. The cellular reaction was evaluated by specular microscopy of the anterior IOL surface. Anterior and posterior capsule opacification (PCO) was assessed semiquantitatively by biomicroscopy. Flare was measured with a Kowa FC-1000 laser flare-cell meter.

RESULTS

Regarding uveal biocompatibility, the hydrophobic acrylic IOLs showed the highest incidence of late foreign-body cell reaction (AcrySof, 30%; AR40, 17%) followed by the hydrophilic acrylic (MemoryLens, 8%; Hydroview, 4%) and silicone (CeeOn 920, 4%; CeeOn 911A, 0%) (P =.0044). In all cases, the cellular reaction was low grade and clinically insignificant. Regarding capsular biocompatibility, some eyes developed lens epithelial cell (LEC) outgrowth on the anterior IOL surface. The highest incidence was in the hydrophilic acrylic group (Hydroview, 85%; MemoryLens, 27%) followed by the hydrophobic acrylic (AcrySof, 4%; AR40, 3%). No silicone IOL had LECs on the anterior surface. The difference among IOL groups was significant (P =.0001). Anterior capsule opacification was more predominant in the hydrophobic IOL groups. Posterior capsule opacification of the central 3.0 mm area was lowest in the groups with a sharp-edged optic (CeeOn 911A, AcrySof) followed by the round-edged silicone (CeeOn 920), hydrophobic acrylic (AR40), and hydrophilic acrylic IOLs (P =.0001). There was a significant difference in flare between the AR40 lens and the Hydroview, MemoryLens, CeeOn 911A, and CeeOn 920 (P <.004). There was no statistically significant difference in the postoperative cell count at 1 year. The power calculation showed that the sample size was sufficient.

CONCLUSIONS

The differences in cellular reaction, although clinically mild in normal eyes, indicate that there were more giant cells with hydrophobic acrylic IOLs and an increased tendency toward LEC outgrowth with hydrophilic lenses. The incidence of PCO was lowest in the hydrophobic IOL groups, especially in groups with a sharp-edged optic. Second-generation silicone IOLs with a sharp edge had good uveal and capsular biocompatibility 1 year after surgery.

Proliferation of lens epithelial cells on the Acrysof intraocular lens: clinical and histological features of a case

Postoperative deposits on the surface of intraocular lenses (IOLs) have been demonstrated in vivo for many IOL material types. The Acrysof acrylic lens develops a granular material extending from the capsulorhexis margin onto the IOL's anterior surface during the first 4 weeks after surgery in a significant proportion of cases. Complete resolution of this membrane occurs by 3 months in almost all cases. The case is presented of an 81-year-old woman who had a persisting membrane coverng the IOL surface at 6 months. This membrane was removed surgically and pathology showed the constituent cells to be of lens epithelial cell origin.

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

PURPOSE

To compare the clinical performance of 2 foldable intraocular lenses (IOLs) with sharp optic edges in terms of uveal and capsular biocompatibility.

SETTING

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

METHODS

Fifty eyes scheduled for cataract surgery were included in this comparative study. A standardized surgical protocol was used, and all operations were performed by 1 experienced surgeon. Two posterior chamber lens types of similar design with a 6.0 mm sharp-edged optic and poly(methyl methacrylate) haptics were used. Twenty-five eyes received an AcrySof acrylic IOL (Alcon), and 25 eyes received a CeeOn 911A silicone IOL (Pharmacia). Relevant data were collected at a 3-year follow-up examination. To evaluate uveal biocompatibility, anterior chamber laser flare and cell measurements and inflammatory cell reactions were monitored. Cellular biocompatibility was investigated by examining anterior capsule opacification (ACO), posterior capsule opacification (PCO), and lens epithelial cell (LEC) ongrowth on the IOL's anterior surface. Factors such as intralenticular glistenings and IOL decentration were also evaluated.

RESULTS

Anterior chamber flare and cells and the inflammatory cell reaction were significantly lower in the CeeOn 911A group. There was no statistically significant difference in ACO, PCO, and LEC ongrowth between the 2 groups. The AcrySof lenses showed significantly better centration and a higher density of intralenticular glistening.

CONCLUSIONS

The findings show that a sharp-edged optic design is, to date, the most effective method of reducing the rate of PCO. Despite a subclinical foreign-body reaction in the AcrySof group, both lenses had a high degree of capsular and uveal biocompatibility.

Anterior capsule opacification: correlation of pathologic findings with clinical sequelae

OBJECTIVE

To evaluate the degree of anterior capsule opacification (ACO) in human eyes obtained postmortem containing various rigid and foldable posterior chamber intraocular lens (PC-IOL) designs and compare the findings with clinical sequelae of capsular shrinkage.

DESIGN

Comparative autopsy tissue study with clinicopathologic correlations.

MATERIALS

Three hundred formalin-fixed human eyes containing the following PC-IOL styles were analyzed: (1) one-piece polymethyl methacrylate (PMMA) optic-PMMA haptic (n = 50), one-piece silicone-plate IOL, with large (2) or small (3) fixation holes (n = 35), (4) three-piece PMMA optic-Prolene haptic (n = 50), (5) three-piece acrylic optic-PMMA haptic (n = 55), three-piece silicone optic with PMMA (6) or polyimide (7) haptics (n = 30), and (8) three-piece silicone optic-Prolene haptic (n = 80) lenses.

TESTING

The eyes were sectioned in the equatorial plane for gross examination of the capsular bag from a posterior view. The cornea and iris were then excised for evaluation from an anterior view.

MAIN OUTCOME MEASURES

ACO was scored in each eye from 0 to IV, according to the degree/area of capsule opacification. Capsulorrhexis size and IOL decentration were measured with calipers.

RESULTS

The overall differences among the IOL groups regarding the three parameters were significant (ACO score: P < 0.001; capsulorrhexis diameter: P = 0.036; IOL decentration: P = 0.012). Mean ACO scores were highest with the large- and small-hole one-piece silicone-plate lenses (2.543 +/- 0.950) and lowest with the three-piece acrylic optic-PMMA haptic lenses (0.600 +/- 0.710). Of 10 cases of capsulorrhexis phimosis observed in the study, 7 cases were associated with three-piece silicone optic-Prolene haptic lenses, which also presented the highest mean decentration (0.375 +/- 0.601 mm).

CONCLUSIONS

Our results confirm previous histopathologic observations that the rate of ACO is the lowest with acrylic lenses and higher with plate-haptic silicone IOLs. Nevertheless, clinical sequelae of capsular shrinkage are also very important with three-piece silicone optic-Prolene haptic designs. Thus, IOL material and design are significant factors in the development of ACO, but they ultimately also influence the clinical presentation of capsular shrinkage.

Lens epithelial cell outgrowth on 3 types of intraocular lenses

PURPOSE

To compare the outgrowth of lens epithelial cells (LECs) on 3 types of intraocular lenses (IOLs) to determine the influence of lens material and lens design (optic edge) on this phenomenon.

SETTING

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

METHOD

Ninety eyes scheduled for cataract surgery were included in a prospective comparative study. A standardized surgical procedure was performed by 1 experienced surgeon. Patients received 1 of 3 types of posterior chamber IOLs of similar design with a 6.0 mm optic and poly(methyl methacrylate) haptic: AcrySof (Alcon), HydroView (Bausch & Lomb), or Sensar (Allergan). Each IOL type was implanted in 30 eyes. Postoperative biomicroscopic examinations were performed 1, 3, 7, 30, 90, and 180 days and 1 year after surgery. Lens epithelial cells in each quadrant of the anterior lens surface were subjectively graded. The product with the highest density and the number of quadrants with this density were used to measure LEC outgrowth.

RESULTS

Statistically significant differences (P <.05) were seen between the hydrophilic IOL and the 2 hydrophobic lenses from day 30 until the final examination. The HydroView lens had a higher number of LECs on its anterior surface than the AcrySof or Sensar IOL. There were no statistically significant differences between the 2 acrylic IOLs at any measurement.

CONCLUSION

The findings suggest that lens surface properties have a greater influence on LEC outgrowth than lens design (ie, sharp optic edge).

Eradication of posterior capsule opacification: documentation of a marked decrease in Nd:YAG laser posterior capsulotomy rates noted in an analysis of 5416 pseudophakic human eyes obtained postmortem

OBJECTIVE

(1) To report the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy rate (%) of eight rigid and foldable intraocular lens (IOL) designs in a series of 5416 pseudophakic human eyes obtained postmortem, accessioned in our center between January 1988 and January 2000. (2) To identify factors that are instrumental in reducing the incidence of posterior capsule opacification, (PCO, secondary cataract) and hence the need for Nd:YAG laser posterior capsulotomy.

DESIGN

Comparative autopsy tissue analysis.

PARTICIPANTS

A total of 5416 globes with posterior chamber intraocular lens (PC-IOLs) obtained postmortem received from Lions Eye Banks between 1988 and 2000.

METHODS

Miyake-Apple posterior photographic technique. Special reference was given to the presence or absence of Nd:YAG laser posterior capsulotomy orifice on the posterior capsule of each eye.

MAIN OUTCOME MEASURES

The Nd:YAG laser posterior capsulotomy rate (%) as of January 2000 was documented. In addition, the Nd:YAG laser posterior capsulotomy rate for each lens was plotted on a monthly basis for the same period, creating a computerized trend or "timeline" for each IOL style.

RESULTS

Relatively high Nd:YAG laser posterior capsulotomy rates ranging from 20.3% to 33.4% were noted with four relatively older designs (high incidence of implantation between 1988 and the early 1990s). Four modern foldable IOLs manufactured from silicone and acrylic materials had significantly lower Nd:YAG laser posterior capsulotomy rates ranging from 0.9% (Alcon Acrysof) to 17.1%. The difference in Nd:YAG rates among the eight IOL designs was found to be significant (P < 0.0001, chi-square test). Comparing foldable versus rigid designs, the foldable IOLs were associated with a much lower Nd:YAG laser posterior capsulotomy rate (14.1% vs. 31.1%).

CONCLUSIONS

By use of the six factors regarding surgical technique and IOL choice described in this article, we strongly believe that the overall incidence of PCO and hence the incidence of Nd:YAG laser posterior capsulotomy is now rapidly decreasing from rates as high as 50% in the 1980s to early 1990s. Surgical tools and IOLs are now available to bring these rates down to single digits. Careful application and use of these tools by surgeons can genuinely lead in the direction of virtual eradication of secondary cataract, the second most common cause of visual loss worldwide.

Capsulotomy

Research is continually seeking to better describe the relationship between pseudophakic capsular opacification and underlying cell biology, surgical technique, and intra-ocular lens biomaterial and design. Outcomes are reviewed from prospective, randomized studies that investigate the importance of capsulorhexis size, pharmacological treatment, and lens material in influencing capsular opacification and the need for capsulotomy. The results of several studies support the role of lens edge profile in inhibiting lens epithelial cell migration. A large post-mortem study also examines how lens type may affect anterior capsular opacification formation. Of particular interest is a histological report that sheds additional light on understanding cellular processes in posterior capsu-lar opacification.

Posterior capsule opacification and anterior capsule opacification

Posterior capsule opacification (PCO) is still the most frequent complication of cataract surgery. A variety of studies has led to a better understanding of the pathogenesis of PCO, and strategies of molecular biology have produced new therapeutic options, such as immunological techniques or gene therapeutic approaches. Surgical strategies and intra-ocular lens-dependent factors also are capable to reduce the rate of PCO. In-the-bag implantation of intra-ocular lenses with a sharp optic edge seems to be effective in inhibiting equatorial lens epithelial cell migration to the center of the posterior capsule. Several PCO documentation systems have been developed that will lead to more exact and better comparable recording of PCO rates. In the year 2000, PCO or secondary cataract is still the most frequent complication after extracapsular cataract surgery. In a 1998 meta-analysis, PCO rates of 11.8% 1 year after extracapsular cataract surgery with intraocular lens implantation, 20.7% after 3 years, and 28.4 % after 5 years have been reported. For the United States, it has been estimated that the overall expenses for treatment of PCO are only exceeded by the costs for cataract treatment itself. In the past decade, a lot of experimental and clinical studies have been performed on this topic. They have led to 1) to a better understanding of the pathogenesis of the development of anterior and posterior capsule opacification; 2) more objective and better comparable systems of documentation and analysis of PCO; and a number of 3) surgical and 4) pharmaceutical strategies to prevent PCO.

Adhesion of fibronectin, vitronectin, laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 1: histological sections

PURPOSE

To evaluate fibronectin, vitronectin, laminin, and collagen type IV adhesion to poly(methyl methacrylate) (PMMA), silicone, hydrophobic soft acrylate, and hydrogel intraocular lenses (IOLs) in pseudophakic human autopsy eyes.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Thirty-eight autopsy eyes containing PMMA, silicone, hydrophobic acrylate, or hydrogel IOLs were assessed. Histological sections were prepared from each eye, and immunohistochemical analyses were performed for fibronectin, vitronectin, laminin, and collagen type IV. One hundred fifty-two specimens were analyzed.

RESULTS

A sandwich-like structure (anterior or posterior capsule/fibronectin/1 cell layer/fibronectin/IOL surface) was seen in 12 of 14 autopsy eyes with soft acrylate IOLs, 3 of 10 with a PMMA IOL (P =.0094), 1 of 10 with a silicone IOL (P =.0022), and 0 of 4 with a hydrogel IOL (P =. 0041). The thicker fibrocellular tissue on the inner surface of the anterior or posterior capsule that was in contact with silicone IOLs was lined with collagen type IV. Vitronectin and laminin were not found at the fibrocellular tissue-IOL interface in any specimen.

CONCLUSIONS

This study seems to confirm the sandwich theory of posterior capsule opacification in eyes with an IOL and suggests that fibronectin may be the major extracellular protein responsible for the attachment of hydrophobic soft acrylate (AcrySof(R)) IOLs to the capsular bag. This may represent a true bioactive bond between the IOL and lens epithelial cells or between the IOL and the capsular bag and may be one reason the PCO and neodymium:YAG capsulotomy rates are lower in eyes with a soft acrylate IOL.

Interlenticular opacification: clinicopathological correlation of a complication of posterior chamber piggyback intraocular lenses

PURPOSE

To present a clinicopathological correlation of 2 pairs of piggyback posterior chamber intraocular lenses (PC IOLs) explanted because of opacification between the lens optics.

SETTING

Gayton Health Center, Eyesight Associates of Middle Georgia, Warner Robins, Georgia, and Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Two pairs of piggyback AcrySof lenses were explanted from 2 patients with significant visual loss related to opacification between the optics. They were submitted for pathological analysis. Gross and histopathological examinations were performed, and photomicroscopy was used to document the results.

RESULTS

Gross examination showed accumulation of a membrane-like white material between the lenses. Histopathological examination revealed that the tissue consisted of retained/proliferative lens epithelial cells (bladder cells or pearls) mixed with lens cortical material.

CONCLUSION

Piggyback PC IOLs were explanted in 2 cases because of a newly described complication, interlenticular opacification. Three surgical means may help prevent this complication: meticulous cortical cleanup, especially in the equatorial region; creation of a relatively large continuous curvilinear capsulorhexis to sequester retained cells peripheral to the IOL optic within the equatorial fornix; insertion of the posterior IOL in the capsular bag and the anterior IOL in the ciliary sulcus to isolate retained cells from the interlenticular space.