Ulrich F.C. Legler

Inhibition of posterior capsule opacification: The effect of colchicine in a sustained drug delivery system

ABSTRACT We investigated the effect of colchicine in a sustained drug delivery system on posterior capsule opacification (PCO) in rabbit eyes. A polymer matrix wafer, which diffused colchicine at a steady rate, was implanted in the capsular bag of 34 eyes after the lens material was removed by endocapsular phacoemulsification. Three different drug concentrations were used in the rabbit eyes, which were compared with control eyes containing the polymer matrix wafer without colchicine. The mean PCO score was highest in the control group without colchicine and increased steadily over 12 weeks. The rate of PCO formation in all eyes treated with colchicine was significantly lower than in the control group. There was no statistically significant improvement in PCO inhibition with the higher colchicine dosages. Side effects included inflammatory anterior chamber reaction and corneal and retinal complications and were most notable with the highest drug concentration. Slow release of colchicine reduces PCO formation in the rabbit. The optimal biocompatible dosage must be carefully determined and warrants further investigation.

Complications of Intraocular Lenses with Special Reference to an Analysis of 2500 Explanted Intraocular Lenses (IOLs)

Abstract The incidence and types of complications seen with the major intraocular lens (IOL) types in a series of 2500 explant cases is reported. We confirm that the rate of complications is higher with anterior chamber IOLs (AC-IOLs) and with iris-fixated IOLs (IF-IOLs) than with posterior chamber IOLs (PC-IOLs). However, the open-loop AC-IOL fared better than the closed-loop designs. Although tissue complications of PC-IOLs (inflammation, glaucoma, cystoid macular oedema and retinal detachment) have decreased markedly, this study shows that decentration/ malposition remains a significant problem. With increased use of smaller diameter or aspherical optic (5.5 mm × 5.5 mm or 5 mm × 6 mm), as well as increasing use of bifocal/multifocal IOLs, it is important that the problem of decentration be addressed.

Clinicopathologic Study of the Effect of Radial Tears and Loop Fixation on Intraocular Lens Decentration

PURPOSE The purpose of this study is to determine the effect of loop fixation and anterior capsular tears on intraocular lens (IOL) decentration. METHODS A retrospective measurement of IOL decentration was performed on 144 human eyes with posterior chamber (PC) IOLs obtained after death. RESULTS Decentration in eyes with asymmetrical bag-sulcus fixation (mean +/- standard deviation, 0.64 +/- 0.39 mm) was significantly higher than eyes with symmetrical fixation. In the presence of radial tears, symmetrically fixated IOLs in either the capsular bag or the ciliary sulcus decentered to a similar degree, 0.35 +/- 0.25 mm and 0.4 +/- 0.26 mm, respectively. The least decentration was observed with capsular fixation and no radial tears (0.18 +/- 0.09 mm). This was significantly less decentration than with any other form of fixation in the presence of radial tears. CONCLUSION This study shows that capsular fixation with no radial tears, as can be achieved by using the continuous curvilinear capsulorhexis, is associated with the least decentration.

Prospective experimental study of factors related to posterior chamber intraocular lens decentration

ABSTRACT The effect of poterior chamber intraocular lens (IOL) dimensions, design, style, loop fixation, and anterior capsular tears on decentration were investigated in an experimental model. Nine posterior chamber IOLs of various designs and styles with loop diameters between 12.0 and 14.0 mm and optic diameters between 5.0 and 7.0mm were implanted in human eyes obtained post mortem. Symmetrical and asymmetrical fixation were investigated in eyes with and without radial tears using the Miyake posterior view technique. Location of IOL loops proved to be most significant factor in IOL decentration. Decentration was least with symmetrical bag/bag fixation and no radial tears (mean = 0.20 ± 0.05 mm). Asymmetrical bag/sulcus fixation in the presence of anterior capsular tears was associated with the highest decentration rate (mean 0.68 ± 0.28 mm). Optic size and total loop diameter had no apparent effect on IOL centration in the immediate postoperative period.

Posterior Continuous Curvilinear Capsulorhexis: An Experimental Study with Clinical Applications

The posterior continuous curvilinear capsulorhexis technique has been advocated in cases of posterior capsule rupture during extracapsular cataract extraction. The authors compared posterior continuous curvilinear capsulorhexis with posterior capsular sharp-edged tears. Two different types of forces were experimentally created on the posterior capsule of 30 human eyes obtained after death: (1) implantation and dialing of posterior chamber intraocular lenses (PC IOLs) and (2) increased intravitreal pressure by injection of balanced salt solution. All posterior capsular tears extended toward the equator, causing major capsular defects. In contrast, the posterior continuous curvilinear capsulorhexis remained intact in all cases. This experimental study proves that in cases where an inadvertent posterior capsular tear occurs, a posterior continuous curvilinear capsulorhexis is useful in preventing further capsular damage. Also, in cases where a posterior capsulotomy is indicated, a smooth edge created by a posterior continuous curvilinear capsulorhexis may be useful to maintain the integrity of the capsular bag for PC IOL capsular implantation.

Loop memory of posterior chamber intraocular lenses of various sizes, designs, and loop materials

ABSTRACT Looped intraocular lenses (IOLs) fixate by exerting centripetal pressure on the ocular tissues. The ability of the flexible loops to maintain pressure depends on their rigidity (i.e., resistance to flexion) and their “memory” (i.e., ability to restore original configuration after a long period of compression). We studied the memory of 30 different posterior chamber IOLs, with loops made of polypropylene (PP) and poly(methyl methacrylate) (PMMA), of various diameters, styles, and designs. The lenses were inserted into plastic wells, 9.5 mm in diameter, and immersed in water (37°C) for one month. They were then placed on an open plate and allowed to re‐expand for one month. Loop memory was calculated as the difference in diameter between the initial (pretest) measurement and measurements taken during the compression and release periods. The results showed that short (12.0 to 12.5 mm) IOLs had relatively better memory than longer (13.5 to 14.0 mm) IOLs. Those with PP loops expanded more and for longer periods than those of comparable size and design with PMMA loops. One‐piece, all‐PMMA lenses exhibited the best loop memory. These lenses have the high rigidity of the PMMA material and the good memory of the design. Thus, the total IOL diameter can be reduced to 12.0 mm while providing long‐term constant pressure on the capsular bag to maintain stable fixation.

Clînicopathologic Study of Ocular Trauma in Eyes With Intraocular Lenses

Data on 41 cases (37 intraocular lenses and four globes) of intraocular lenses explanted or expulsed after ocular trauma were retrieved from over 5,000 intraocular lenses and 1,200 globes. The age of the male and female donors varied significantly (male, 64.4 +/- 13.1 years; female, 75.5 +/- 12.6 years; P = .0334). Twenty-two were posterior chamber, 11 were anterior chamber, and eight were iris-fixated lenses. The mean implant durations were 0.66 +/- 0.9 years for posterior chamber intraocular lenses, 4.0 +/- 3.4 years for anterior chamber lenses, and 9.0 +/- 4.9 years for iris-fixated lenses. Accidental falling was the most common trauma in 14 of 21 cases (67%). In the posterior chamber intraocular lens group, trauma was more severe and resulted in rupture of the globe in 19 of 22 cases (86%) and expulsion of the intraocular lens in 15 of 22 cases (68%). Rupture usually occurred at the surgical wound, even when the trauma happened five years postoperatively. In contrast, most of the eyes with anterior chamber intraocular lenses and iris-fixated intraocular lenses did not rupture, but a minor trauma often resulted in intraocular lens dislocation and secondary complications that necessitated intraocular lens explantation. The pathologic findings were nonspecific (proteinaceous deposits, blood and pigment adherent to the intraocular lens). Severity of trauma and pathologic findings were not correlated. Posterior chamber intraocular lenses are more resistant to minor ocular trauma compared to anterior chamber and iris-fixated intraocular lenses.

The Capsular Bag after Short- and Long-term Fixation of Intraocular Lenses

PURPOSE To investigate the effect of posterior chamber intraocular lens (PC IOL) size and construction on the capsular bag in human cadaver eyes. METHODS Studies were done at two timeframes: (1) short term (prospective)--the effect of 12 different IOLs on the capsular bag configuration after experimental implantation; and (2) long term--(retrospective) analysis of eyes with PC IOLs obtained post-morterm. RESULTS The short-term study showed the maximal diameter of the capsular bag to be 11.0 mm for IOLs with total diameter of 12.0 mm and 11.5 mm for 13.5- to 14.0-mm IOLs. Longer IOLs caused more ovaling of the bag with stress lines (striae) on the posterior capsule. Secondary processes such as proliferation of epithelial cells (Soemmering ring) and capsular fibrosis caused the capsular bag to resume a more circular shape with irregular contour. The area of contact between the IOL loops and the capsular equator was significantly lower in eyes with radial tears and IOLs with the J-loop design compared with the C-loop design. In both the short- and long-term groups, maximal capsular diameter did not exceed 12.0 mm. CONCLUSIONS The results of this study suggest that using the capsulorrhexis technique, a 12.0-mm total diameter IOL is sufficient to provide stable capsular fixation.

Scanning electron microscopic study of modern silicone intraocular lenses

ABSTRACT Silicone, as manufactured today, appears to be a biocompatible material. The safety and efficacy of silicone lenses are primarily related to the intraocular lens (IOL) design. We compared the edge finish of two three‐piece polypropylene loop foldable silicone IOL designs (Allergan Medical Optics) and three one‐piece designs (Staar Surgical Co., CooperVision‐Cilco). Except for an early Staar one‐piece design, all lenses including the more recent Staar lenses had acceptably smooth edges with minimal molding flash.

Transscleral cyclophotocoagulation using a semiconductor diode laser in cadaver eyes.

We studied the effectiveness of semiconductor diode laser transscleral cyclophotocoagulation in cadaver eyes using the Miyake technique and light microscopy. Thermal lesions in the ciliary processes were induced with 0.7-second, 1200-mW, and 100- to 500-microns applications, 0.5 mm from the surgical limbus and defocused 1 mm posteriorly. An effective ciliary body reaction was observed grossly as tissue blanching, shrinkage, and pigment dispersion; and histologically, as coagulation necrosis and epithelial cell disruption. No damage to crystalline or intraocular lenses was evident. This successful application of diode laser transscleral cyclophotocoagulation in cadaver eyes suggests that it may prove useful in treating patients with glaucoma.