Preventive effect of a second-generation silicone intraocular lens on posterior capsule opacification

Effect of time and temperature-dependent changes of IOL material properties on IOL: Lens capsule interactions

Posterior Capsule Opacification (PCO) is the most common complication associated with Intraocular Lens (IOL) implantation. Based on the assumption that the interactions between an IOL and the lens capsule (LC) may influence the extent of PCO formation, a new in vitro model was developed to quantify the adhesion force of an IOL to simulated LC using a custom-designed micro-force tester. Using this system, we examined the influence of temperature (room temperature vs. body temperature) and incubation time (0 vs. 24 h) on the adhesion force between IOLs and LCs. The results show that, in line with clinical observations of PCO incidence, the adhesion force increased at body temperature and with increase in incubation time in the following order, Acrylic foldable IOLs > Silicone IOLs > PMMA IOLs. By examining the changes of surface properties as a function of temperature and incubation time, we found that acrylic foldable IOLs showed the largest increase in their hydrophilicity and reported the lowest surface roughness in comparison to other IOL groups. Coincidentally, using a newly established macromolecular dye imaging system to simulate cell migration between IOLs and LC, we observed that the amount of macromolecular dye infiltration between IOLs and LCs was in the following order: PMMA IOLs > Silicone IOLs > Acrylic foldable IOLs. These results support a new potential mechanism that body temperature, incubation time, surface hydrophilicity and smoothness of IOLs greatly contribute to their tight binding to LCs and such tight binding may lead to reduced IOL: LC space, cell infiltration, and thus PCO formation.

Prevention of lens epithelial cell growth in vitro using mibefradil-containing PLGA micro particles

The prevention of the posterior capsule opacification is still unsolved. To interfere with proliferating cells the T-type calcium channel antagonist Mibefradil was immobilized in poly-lactic-co-glycolic-acid micro particles which were fixed at a capsular tension ring and tested in a human organ culture model as well as in human lens cells HLE-B3 in vitro. It is feasible to get a release significantly affecting cell viability and growth evaluated by MTT test and cell cycle analysis. In addition, Bionas^® sensor chips were used for time-dependent adhesion experiments in living lens cells. Interestingly, the concentration of Mibefradil which inhibited subconfluent cells is not effective in confluent cells. This is an important feature for the protection of the intact tissue in the eye.

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.

Longterm results of 1 CU® accommodative intraocular lens implantation: 2-year follow-up study

PURPOSE

To evaluate the longterm efficacy of 1 CU accommodative intraocular lenses (IOLs) to restore near visual performance.

METHODS

This prospective study comprised 14 eyes previously included in a 6-month, case-control clinical trial, undergoing phacoemulsification and implantation of a 1 CU accommodative IOL. The main outcome measures were subjective refraction, uncorrected distance visual acuity (UCDVA), best corrected distance VA (BCDVA), distance-corrected near VA (DCNVA), best corrected near VA (BCNVA), and subjective amplitude of accommodation (AA). In addition, anterior and posterior capsule opacification were assessed. Patients were examined over a 2-year follow-up period.

RESULTS

Distance and near visual performance worsened after 6 months. Uncorrected DVA and BCDVA were 0.8 +/- 2.1 and 1.0 +/- 0.8 at 6 months and 0.4 +/- 0.1 and 0.6 +/- 0.1 at 1 year, respectively (p = 0.001). Distance-corrected NVA and BCNVA were 3.7 +/- 2.1 Jaeger (J) and 1.0 +/- 0.7 J at 6 months and 8.1 +/- 0.7 J and 1.5 +/- 0.5 J at 1 year, respectively (p = 0.001). Anterior and posterior capsule opacification were present, respectively, in 28% and 21% of patients at 6 months and in 100% of patients at 1 and 2 years (p < 0.001). After Nd:YAG laser capsulotomy (performed in 100% of patients), UCDVA and BCDVA increased to 0.7 +/- 0.2 (p = 0.007) and 1.0 +/- 0.1 (p = 0.001), respectively, at 2 years. Distance-corrected NVA improved to 7.3 +/- 0.5 J (p = 0.006). Mean AA was 1.9 +/- 0.8 D at 6 months, 0.3 +/- 0.2 D (p = 0.004) at 1 year and 0.3 +/- 0.2 D at 2 years.

CONCLUSIONS

Patients implanted with 1 CU IOLs lost their accommodation capacities with time because of the high incidence and degree of anterior and posterior capsule opacification. The accommodative lens material and design may have played a role in capsule fibrosis.

Effect of primary posterior continuous curvilinear capsulorhexis on clinical performance of ACR6D SE single-piece hydrophilic acrylic intraocular lenses

PURPOSE

To evaluate the effects of a primary posterior continuous curvilinear capsulorhexis (PCCC) on the clinical performance of a single-piece hydrophilic acrylic intraocular lens (IOL) with haptic angulation.

SETTING

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

METHODS

A prospective study of 52 patients with bilateral age-related cataract was conducted. Patients had standard cataract surgery with implantation of the same IOL in both eyes. Randomly, a PCCC was created in 1 eye and the posterior capsule was left intact in the fellow eye. Assessed parameters were visual axis opacification (VAO) in eyes with a PCCC or regeneratory posterior capsule opacification (PCO) in eyes without PCCC (scale 0 to 10) in the central (3.0 mm eccentricity), intermediate (3.0 to 4.5 mm eccentricity), and peripheral (>4.5 mm eccentricity [capsulorhexis edge]) areas; neodymium:YAG (Nd:YAG) laser capsulotomy or laser polishing of ongrowing lens epithelium; anterior capsule opacification (ACO); best corrected visual acuity (BCVA); and contrast sensitivity.

RESULTS

Thirty patients completed the 2(1/2)-year follow-up. Visual axis opacification was significantly lower in the central region in the PCCC group (mean 0.5 +/- 0.7 [SD]) than PCO in the central region of the non-PCCC group (mean 1.1 +/- 1.1) (P = .02). Forty percent in the non-PCCC group had an Nd:YAG laser capsulotomy during the follow-up period; none in the PCCC group had laser polishing. There were no significant differences in ACO, SE, BCVA, or contrast sensitivity. There was no additional gain in BCVA or contrast sensitivity in eyes with a PCCC compared with eyes without a PCCC when VAO and PCO were low.

CONCLUSION

A PCCC significantly reduced PCO formation within the central 3.0 mm eccentricity as well as the need for Nd:YAG laser capsulotomy in eyes with a single-piece hydrophilic acrylic IOL with angulated haptics.

Clinical effects of primary posterior continuous curvilinear capsulorhexis in eyes with single-piece hydrophilic acrylic intraocular lenses with and without haptic angulation

PURPOSE

To evaluate the clinical effects of a primary posterior continuous curvilinear capsulorhexis (PCCC) on the intraocular performance of hydrophilic acrylic single-piece intraocular lenses (IOLs) with and without haptic angulation.

SETTING

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

METHODS

A prospective study comprised 52 patients with bilateral age-related cataract who had standard cataract surgery including a PCCC. One eye of each patient was randomized to receive a hydrophilic acrylic IOL with haptic angulation (ACR6D SE, Laboratoires Cornéal) and the contralateral eye, a hydrophilic acrylic IOL without haptic angulation (C-flex 570C, Rayner). The following parameters were assessed: regeneratory posterior opacification (RPO) in the central, intermediate, and peripheral areas (scale 0 to 10); anterior capsule opacification (ACO); best corrected visual acuity (BCVA); and contrast sensitivity (CSF).

RESULTS

Thirty-one patients completed the 1(1/2)-year follow-up. In both IOL groups, RPO within the PCCC was slight in the central area, with a mean score of 0.33 +/- 0.84 (SD) in the angulated IOL group and 0.16 +/- 0.57 in the nonangulated IOL group (P = .29). The mean RPO score in the peripheral area was 2.07 +/- 1.37 and 2.35 +/- 1.45, respectively (P = .12). The difference between the central and peripheral areas was 1.74 in the angulated IOL group (P<.00001) and 2.19 in the nonangulated IOL group (P<.00001). Haptic deformation occurred in 9 eyes (29%) with an angulated IOL and no eye with a nonangulated IOL. There was significantly more ACO in the nonangulated IOL group (P = .012). There were no significant differences in BCVA or CSF between the 2 groups.

CONCLUSIONS

Creating a PCCC led to significantly lower RPO intensity within the PCCC area than in the peripheral area in eyes with hydrophilic acrylic IOLs with and without haptic angulation. Haptic angulation had no apparent significant influence on the intensity of RPO or on BCVA and CSF. Haptic deformation may occur in hydrophilic IOLs with angulated haptics.

Influence of three-piece and single-piece designs of two sharp-edge optic hydrophobic acrylic intraocular lenses on the prevention of posterior capsule opacification: a prospective, randomised, long-term clinical trial

BACKGROUND

Posterior capsule opacification (PCO) is still a major long-term complication of modern cataract surgery. We evaluated the impact of sharp-edged intraocular lenses (IOLs) with different haptic designs made from the same hydrophobic acrylic material on posterior and anterior lens capsule opacification.

SETTING

Eye clinic of Kaunas University of Medicine, Lithuania. Prospective randomised clinical study.

METHODS

Seventy-four eyes of 74 patients scheduled for cataract surgery were included in a prospective randomised clinical study. Thirty-seven eyes of 37 patients received a three-piece acrylic hydrophobic (AcrySof, MA3OBA, Alcon) IOL; and thirty-seven eyes of 37 patients received a one-piece acrylic hydrophobic (AcrySof, SA3OAL, Alcon) IOL. Visual acuity, anterior capsule opacification (ACO), capsular folds, capsulorrhexis/optic overlapping and posterior capsule opacification (PCO) were evaluated. ACO was assessed subjectively. PCO values in the entire IOL optic area and in the central 3 mm optic zone were assessed using a photographic image-analysis system (EPCO2000). Follow-ups were performed postoperatively at 1 day, 6 months, 1 year and 2 years.

RESULTS

There were no significant differences in best corrected visual acuity, grade of ACO and capsulorrhexis/optic overlapping between IOL types during the follow-up period. Patients in the one-piece acrylic hydrophobic IOL group more frequently presented with capsular folds behind the IOL optic area than those in the three-piece IOL group. In the three-piece acrylic hydrophobic IOL group, PCO values (mean (SD)) of the entire IOL optic area were significantly lower six months postoperative (three-piece: 0.002 (0.009); one-piece: 0.007 (0.017); p=0.04), one year postoperative (three-piece: 0.004 (0.016); one-piece: 0.026 (0.041); p=0.001) as well as one year postoperative in the central 3 mm optic zone (three-piece: 0.000 (0.0002); one-piece: 0.019 (0.049); p=0.001). However, two years postoperative, the PCO values of the groups did not show significant differences (entire IOL optic area: three-piece, 0.136 (0.223); one-piece, 0.154 (0.190); p=0.18; central zone: three-piece, 0.023 (0.065); one-piece: 0.020 (0.039); p=0.44).

CONCLUSION

The 2 year follow-up after cataract surgery showed no significant difference in ACO and PCO development between three-piece and one-piece acrylic hydrophobic intraocular lenses.

Hydrophobic acrylic and plate-haptic silicone intraocular lens implantation in diabetic patients

PURPOSE

To compare the capsular and uveal reaction after implantation of a plate-haptic silicone intraocular lens (IOL) (C11UB, Chiron) and a hydrophobic acrylic (AcrySof MA60, Alcon) IOL in diabetic patients.

SETTING

Moorfields Eye Hospital and St. Thomas' Hospital, London, United Kingdom.

METHODS

Thirty-five diabetic patients were recruited consecutively and randomly assigned to have implantation of either of the 2 IOLs. The percentage area of posterior capsule opacification (PCO), anterior capsule contraction (ACC), and postoperative inflammatory indices (flare and cells) were assessed objectively at 2 to 3 weeks, 6 months, and 1 year. Between-group and within-group analyses were conducted using the Student t test or Mann-Whitney test and Friedmann test, respectively.

RESULTS

Between-group analysis showed the percentage area of PCO was significantly greater in patients with plate-haptic silicone IOLs at 6 and 12 months (P = .002). At 6 months, ACC was significantly greater in the plate-haptic group (P = .04), but the difference was not significant at 12 months. There was higher flare in the hydrophobic acrylic IOL group than in the plate-haptic silicone IOL group at 2 to 3 weeks (P = .08). Within-group analysis showed that over the follow-up period, the plate-haptic silicone group, but not the hydrophobic acrylic group, had a progressive increase in PCO (P = .003). In the hydrophobic acrylic group, but not the plate-haptic silicone group, there was a significant reduction in the mean anterior chamber flare value (P = .01). There was no significant difference in visual acuity or contrast sensitivity at any postoperative visit.

CONCLUSION

In diabetic patients, hydrophobic acrylic IOLs can lead to an increased flare in the early postoperative period but they seem to be more favorable than plate-haptic silicone IOLs because the latter lead to more PCO.

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.

[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.

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.

In vivo digital imaging of the square-edged barrier effect of a silicone intraocular lens

PURPOSE

To evaluate and compare by high-magnification digital photography the lens epithelial cell (LEC) response and capsule dynamics in vivo after implantation of a square-edged and a round-edged silicone intraocular lens (IOL) in a fellow-eye study.

SETTING

Private practice and Royal Victoria Hospital, Barrie, and Soldiers' Memorial Hospital, Orillia, Ontario, Canada.

METHODS

After phacoemulsification, a single surgeon implanted a square-edged silicone IOL (SoFlex SE, Bausch & Lomb) in 25 patients who had previously had a conventional round-edged version of the same IOL (SoFlex Li61U, Bausch & Lomb) implanted in their contralateral eye within a 6-week period. SoFlex SE IOL recipients were selected sequentially from those scheduled for surgery within a 3-day period. The IOLs were sequentially photographed 1 week and 1, 3, 6, and 9 months after surgery using magnification of at least x64 through a biomicroscope and a high-resolution digital camera with adapter. Images were transferred to a graphics computer and compared over time.

RESULTS

At 1 week, both designs had evidence of LEC migration along the posterior capsule, with the highest cell density around the 6 o'clock position. At 1 month, both IOL designs showed 360 degrees of anterior and posterior capsule adhesion to the edge of the optic. At 1 month, however, migrating LECs encountered a "damming" effect at the square posterior edge but not at the round edge. A thin fibrotic ring began to form around the SoFlex SE edge at 2 months and was complete for 360 degrees at 3 months. At 9 months, there was no evidence of LEC migration beyond this ring. With round-edged IOLs, the fibrotic ring never fully formed and LEC migration continued posterior to the optic. There was a tight capsule shrink-wrap effect with the square-edged IOLs with the fibrotic ring, allowing minimal IOL movement between 1 month and 9 months. The round-edged IOLs tended to decenter and rotate. Anterior capsulorhexis contraction was greater at every time point with the round-edged IOLs than with the square-edged IOLs.

CONCLUSION

Early contact inhibition of LECs by a square-edged IOL design and its effects were demonstrated in vivo with sequential, high-resolution digital photography and commercially available graphics software.

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.

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.

Effect of the optic size of a single-piece acrylic intraocular lens on posterior capsule opacification

PURPOSE

To investigate the effect of the optic size of an intraocular lens (IOL) with sharp optic edges on posterior capsule opacification (PCO).

SETTING

Nishi Eye Hospital, Osaka, Japan.

METHODS

In 5 rabbits, a single-piece 5.5 mm optic AcrySof IOL (Alcon Laboratories) was implanted in 1 eye and a specially fabricated single-piece 7.0 mm optic AcrySof IOL was implanted in the contralateral eye. Histopathological examinations were performed 3 weeks after surgery.

RESULTS

On posterior views, less PCO was noted with the 5.5 mm optic in all rabbits except 1. Histopathological sections demonstrated adhesion of the anterior and posterior capsules between the haptic and optic and the formation of a sharp capsular bend at the posterior optic edge in 3 eyes with the 5.5 mm optic but in no eye with the 7.0 mm optic. Abundant PCO was noted when a sharp capsular bend had not formed.

CONCLUSIONS

Capsular adhesion is a prerequisite of capsular-bend formation. The sharp optic edge alone does not provide a substantial barrier when a capsular bend is not formed. Bulky haptics such as those of the single-piece AcrySof and large optics may hamper capsular adhesion and bend formation.