A comparison of 141 polymacon (Iogel) and 140 poly(methyl methacrylate) intraocular lens implants

Delayed dislocation of an injectable hydrophilic acrylic lens after Nd:YAG capsulotomy in anterior capsular contraction syndrome

Posterior dislocation of IOLs has been reported following Nd:YAG laser for anterior capsule contraction in only 3 cases and these involved plate haptic silicone lenses; while the dislocation of IOLs into the vitreous cavity following posterior Nd:YAG laser capsulotomy have been reported in plate haptic silicone lenses and single piece hydrophilic acrylic (polymacon) lenses. We report a patient who suffered the delayed dislocation of an injectable hydrophilic acylic IOL (SlimFlex-m 123 IOL, PhysIOL, Liège, Belgium) following combined Nd:YAG laser anterior and posterior capsulotomy. We also explore the factors that may predispose to anterior capsular contraction syndrome and IOL dislocation.

Effect of a modified optic edge design on visual function

PURPOSE

To compare the impairment in visual function caused by glare with 2 acrylic intraocular lenses (IOLs) with different modified optic edges.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

METHODS

Fifty-four patients had implantation of an IOL with a textured edge (Alcon MA60AC) in 1 eye and an IOL with a round-anterior, sloped-sided edge (AMO AR40e) in the opposite eye. Visual acuity was measured at 5 contrast visual targets (100%, 25%, 10%, 5%, and 2.5%) (contrast visual acuity) under photopic and mesopic conditions with and without a glare source approximately 1 month after surgery using the Contrast Sensitivity Accurate Tester (Menicon CAT-2000).

RESULTS

The mean mesopic contrast visual acuity at moderate- to low-contrast visual targets was significantly worse in the presence of a glare source in both groups, whereas photopic contrast visual acuity did not change significantly. There were no significant differences between the 2 groups in the mean visual acuity or in photopic or mesopic lighting contrast visual acuity with and without a glare source. Furthermore, there was no significant difference in loss of contrast visual acuity in the presence of glare.

CONCLUSION

Mesopic contrast sensitivity with both acrylic IOLs was impaired significantly in the presence of glare, but the impairment of contrast sensitivity from glare was approximately the same between eyes with a textured-edge IOL and eyes with a round-anterior, sloped-sided edge IOL.

Anterior capsule contraction and intraocular lens decentration and tilt after hydrogel lens implantation

AIM

To prospectively investigate changes in the area of the anterior capsule opening, and intraocular lens (IOL) decentration and tilt after implantation of a hydrogel IOL.

METHODS

100 patients underwent implantation of a hydrogel IOL in one eye and an acrylic IOL implantation in the opposite eye. The area of the anterior capsule opening, and the degree of IOL decentration and tilt were measured using the Scheimpflug videophotography system at 3 days, and at 1, 3, and 6 months postoperatively.

RESULTS

The mean anterior capsule opening area decreased significantly in both groups. At 6 months postoperatively, the area in the hydrogel group was significantly smaller than that in the acrylic group. The mean percentage of the area reduction in the hydrogel group was also significantly greater than that in the acrylic group, being 16.9% in the hydrogel group and 8.8% in the acrylic group. In contrast, IOL decentration and tilt did not progress in either group. No significant differences were found in the degree of IOL decentration and tilt throughout the follow up period.

CONCLUSIONS

Contraction of the anterior capsule opening was more extensive with the hydrogel IOL than with the acrylic IOL, but the degree of IOL decentration and tilt were similar for the two types of lenses studied.

Intraocular lens bioactivity tested using rabbit corneal tissue cultures

PURPOSE

To evaluate the effects of different intraocular lens (IOL) materials on epithelial cell growth to test the sandwich theory; i.e., a bioactivity-based explanation of posterior capsule opacification (PCO) after cataract surgery.

SETTING

Central Hospital, Vaasa, and Institute of Dentistry and Turku Center for Biomaterials, University of Turku, Finland.

METHODS

Rabbit corneal tissue cultures were set up on poly(methyl methacrylate) (PMMA), heparin-surface-modified (HSM) PMMA, silicone, acrylate, and hydrogel IOLs for 1 week. The tissue consisted of intact epithelium and half the thickness of the corneal stroma, which was placed against the IOL. The growth of the epithelium was examined by light microscopy to evaluate the attachment of the corneal explant to the IOL surface.

RESULTS

All tissue samples grew well under the culture conditions. When grown on PMMA, HSM PMMA, silicone, and hydrogel, the tissue did not attach to the IOL or the epithelium grew around the explant, suggesting that the attachment of the stroma to the IOL was poor or nonexistent. Some explants on acrylate IOLs attached directly to the IOL surface with no epithelial ingrowth between the stroma and the IOL.

CONCLUSIONS

This tissue culture method can be used to examine the behavior of corneal tissue in contact with different IOL materials. The results suggest that the acrylate IOL may have bioactive properties. This, with the lens optic's square edge, may hinder lens epithelial cell proliferation and thus prevent PCO.

Contrast sensitivity after extracapsular and intracapsular cataract extraction

Contrast sensitivity function after cataract extraction and intraocular lens implantation has been mainly correlated to the type or the material of the intraocular lens. Our purpose was to identify other possible factors, like posterior capsule, to contrast sensitivity alterations after cataract surgery, comparing patients operated for cataract by techniques that mainly differed on the posterior capsule's integrity. The intraocular lens implanted was either a posterior or an anterior chamber one, always monofocal and made of PMMA. We measured contrast sensitivity function at four spatial frequencies in two groups of operated individuals (group A and B) and in one group of healthy control individuals. Each group consisted of 42 eyes. Group A comprised eyes with intact, clear posterior capsule and posterior chamber monofocal intraocular lens. Group B comprised eyes with ruptured or removed posterior capsule and anterior chamber monofocal intraocular lens. Control group comprised healthy control eyes. A pair matched design was used to compare contrast sensitivity values among the individuals of the three groups. No statistically significant differences in contrast sensitivity values were found when group B patients were compared to healthy controls (p >0.05). Patients of group A exhibited contrast sensitivity function impairment at intermediate and high spatial frequencies when compared to patients of group B (p <0.05) and to controls (p <0.01). It seems that intact posterior capsule provides inferior visual function, in spite of relatively good visual acuity and apparently satisfactory results.

A comparison of visual performance between a rigid PMMA and a foldable acrylic intraocular lens

PURPOSE

To examine post-operative visual outcomes when using micro-incision surgery and a three-piece, foldable acrylic intraocular lens (IOL) and when using small-incision surgery and a one-piece, rigid polymethyl-methacrylate (PMMA) IOL.

METHODS

Phacoemulsification and IOL implantation was conducted by one surgeon on 86 subjects (aged 50-89 years) with cataracts. Of these subjects, 67 completed the study. Subjects were implanted either with a foldable IOL (n = 38) or a rigid IOL (n = 29). Best corrected Snellen visual acuity and contrast sensitivity (2-28 cycles/degree) were measured approximately 2 months post-operatively. Comparisons were made between the pseudophakic groups and an additional group of 28 age-matched, normal subjects (aged 58-81 years). Non-parametric (Kruskal-Wallis and Mann-Whitney U) as well as parametric (ANOVA and Pearson) statistics tests were used in the analysis of results.

RESULTS

All pseudophakes had corrected visual acuity of 6/9 or better. There were no significant differences in visual acuity (Kruskal-Wallis, p = 0.61) or contrast sensitivity (ANOVA, p = 0.33) between the three groups. The mean residual refractive error of the foldable IOL group was hypermetropic in comparison with the rigid IOL group but not significant at the 99% level of probability (Mann-Whitney U, p = 0.02). There was no significant difference in astigmatism between the groups.

CONCLUSIONS

Implanting a foldable acrylic IOL gave no post-operative benefit in visual acuity and contrast sensitivity to pseudophakes over a less expensive rigid PMMA IOL, within this post-operative period. This study did not provide a comparison between the two lenses regarding post-operative complications, in particular the important long-term complication of posterior capsular opacification (PCO). Until and if any particular advantage of a given IOL in reduced incidence of PCO is confirmed, it appears more economical to implant the conventional rigid PMMA IOL using small-incision surgery.

Posterior capsule opacification and capsulotomy rates with taco-style hydrogel intraocular lenses

PURPOSE

To evaluate posterior capsule opacification (PCO) formation and neodymium: YAG (Nd:YAG) laser capsulotomy results in eyes with an logel intraocular lens (IOL).

SETTING

First University Hospital, Vienna, Austria.

METHODS

A retrospective study was done of 108 eyes with one of three types of an logel IOL that had decreased vision from PCO and required posterior capsule discission.

RESULTS

In general, in eyes with sulcus-placed IOLs, a Soemmering's ring formed and the capsulorhexis rim tightly adhered to the posterior capsule, sealing the capsular bag periphery. Elschnig pearls had broken the barrier, invading the retrolental space. In eyes with bag-placed IOLs, there was a gap between the IOL and posterior capsule in which Elschnig pearls had accumulated. This gap frequently extended beneath the flanges to the periphery of the capsular bag, allowing residual lens epithelial cells to proliferate and migrate centrally.

CONCLUSION

The logel lenses led to a high incidence of regeneratory PCO within the gap between the lens and capsule that might be the result of the properties of the lens' hydrogel material rather than its design.

Contrast sensitivity function after cataract extraction and intraocular lens implantation

Divergent contrast sensitivity findings have been reported in patients with intraocular lens implants. The purpose of this study was to determine contrast thresholds of patients with good visual acuity after uncomplicated cataract extraction and posterior chamber conventional IOL implantation. Fifty-two eyes of fifty two patients, who had undergone uncomplicated extracapsular cataract extraction and posterior chamber intraocular lens implantation together with 48 eyes of 48 control subjects were tested for contrast sensitivity function. All of the patients had best corrected visual acuity 0.8 (20/25) or better, on the Snellen scale. Patients with concomitant eye disease were excluded. Contrast sensitivity was measured using stationary sine-wave gratings of four spatial frequencies (3.0 to 18.0 cycles/degree), at the testing distance of 8 feet. A loss of contrast sensitivity was found in patients with intraocular lens implants, compared with control subjects of similar age, sex and visual acuity. The loss was statistically significant at intermediate (6 cyc/deg) and high spatial frequencies (12.0 and 18.0 cycles/degree), while it was not statistically significant at low spatial frequencies (3 cyc/deg). This may be the reason of nonspecific visual complaints ('washed-out images'), despite normal Snellen acuity, after cataract surgery and monofocal IOL implantation.

Visual function in pseudophakic eyes with poly(methyl methacrylate), silicone, and acrylic intraocular lenses

PURPOSE

To evaluate the quality of visual function after cataract surgery and intraocular lens (IOL) implantation with three lens materials.

SETTING

Klinik Dardenne, Bonn Bad Godesberg, Germany.

METHODS

In a prospective, randomized study, 55 patients having uncomplicated phacoemulsification received IOLs made of three materials: 16 received acrylic IOLs, 20 received silicone IOLs, and 19 received poly(methyl methacrylate) (PMMA) IOLs. Pseudophakic patients with accompanying eye diseases were excluded. Visual acuity, glare sensitivity, contrast sensitivity, and mesopic acuity were evaluated 6 weeks postoperatively.

RESULTS

Postoperatively, best corrected visual acuity was excellent in all three lens groups. Acuity under bright light conditions and contrast sensitivity were low in all groups; mesopic acuity was extremely low in 73% of patients. Glare and contrast sensitivity were significantly better with PMMA and acrylic IOLs.

CONCLUSION

The visual quality achieved in pseudophakic eyes with three different lens materials was lower than expected. The results of individual visual function tests were better for PMMA and acrylic IOLs than for silicone IOLs.

Evaluation of 100 consecutive IOGEL 1003 foldable bag-style lenses implanted through a self-sealing tunnel incision

The IOGEL 1003 hydrogel lens, designed for better capsular bag fit, was implanted in 100 consecutive eyes. We evaluated the visual and morphological results obtained with a mean follow-up of six months. Visual acuity was within Food and Drug Administration standards; however, morphological results were less satisfactory. Decentration of 1 mm or more occurred in 24% of the cases. Higher diopter lenses required a minimum incision size of 4 mm and tended to tear when folded. Once in the eye, they regularly came in contact with the iris. A gap between the posterior optic surface and capsule occurred in 61% of eyes. Within the short follow-up period, 9% of eyes required YAG discission because of Elschnig pearl formation. In conclusion, the newer IOGEL 1003 lens performed no better than earlier IOGEL lens models when placed in the bag, and the possible benefit of decreasing posterior lens subluxation after early YAG capsulotomy is offset by the disadvantages.