Internal limiting membrane ablation in pig eyes with the Er:YAG laser under perfluorodecalin.

PURPOSE: The aim of our study was to evaluate the in vivo feasibility of non-contact Er:YAG laser ablation of the internal limiting membrane (ILM), which is recommended for the treatment of macular holes. METHOD: Vitrectomy was performed in 16 eyes of 15 pigs. After perfluorodecalin filling, it was attempted to remove the ILM using a free-running fiber-guided Er:YAG laser (lambda=2.94 microm, pulse length 250 micros, repetition rate 1.7 Hz, radiant exposure 0.6-2.05 J/cm2). The eyes were enucleated either immediately (11 eyes, group 1) or 2 weeks after laser therapy (5 eyes, group 2). Furthermore, in one additional pig eye the retina was carefully treated with microforceps after vitrectomy to assess the damage produced by conventional techniques of ILM peeling. All eyes were examined histologically. RESULTS: Group 1: Nine eyes could be examined (problems with fixation in two eyes). In four of nine eyes, the ILM was either removed or detached, in one eye there was a superficial retinal hemorrhage, and in four eyes the ILM was still intact. In the latter cases, there was no intraoperative whitening or bleeding and no posterior vitreous detachment was present histologically. Group 2: Four eyes (problems with fixation in one eye) could be examined. The ILM was either removed or detached in three eyes. In one eye there was a superficial retinal hemorrhage. In one eye the ILM was not removed and there had neither been intraoperative whitening or hemorrhage nor histologically visible posterior vitreous detachment. In both groups, the nerve fiber layer in treated areas was thicker than in adjacent untreated retina. In one eye the retina was gently manipulated with microforceps in an attempt to perform ILM peeling. This led to damage to all layers of the retina. CONCLUSIONS: Removal of the ILM by Er:YAG laser is possible in vivo. However, the variability of the laser effects calls for further improvement such as a reliable indicator of ablation depth. In any case, any damage to the retina was lesser than that produced by microforceps.

Steady-state electroretinograms and pattern electroretinograms in pigs.

BACKGROUND: Electroretinograms (ERG) or pattern-electroretinograms (PERG) could be valuable for the quantification of potential damage to the pig retina by experimental erbium:YAG laser treatment. We therefore performed a normative study of ERGs and PERGs in pigs. METHODS: We recorded ERGs and PERGs under general anaesthesia in two experiments. In experiment 1 we examined eight eyes from six pigs of 20-25 kg body weight; in experiment 2 we examined four eyes from four pigs of 40-45 kg body weight. We used flash and checkerboard stimuli. In experiment 1, the stimulus parameters were mean luminance 48.3 cd/m2 for checkerboard stimuli, 96.6 cd/m2 for ERG, check sizes of 4 degrees, 8 degrees, and 16 degrees, temporal frequencies were 16 Hz for ERG and 8 rev/s for PERG. Three measurements were repeated after two weeks. Stimulus parameters for experiment 2 were luminance 175 (350) cd/m2, check sizes 1.6 degrees, 3.2 degrees, 6.7 degrees, and 16 degrees, temporal frequencies 6.3 Hz for ERG and 8 rev/s for PERG. Recordings were subjected to Fourier analysis. RESULTS: In experiment 1 the mean ERG amplitude was 1.02 +/- 0.89 microV with a coefficient of variation of 42% for repeat sessions. The mean PERG amplitudes were 0.53 +/- 0.25 microV for 16 degrees checks, 0.36 +/- 0.21 microV for 8 degrees, and 0.25 +/- 0.17 microV for 4 degrees. The mean coefficient of variation between two measurements was 103% for 16 degrees checks, 24% for 8 degrees, and 116% for 4 degrees. In experiment 2 the mean ERG amplitude was 9.72 +/- 3.96 microV. The mean PERG amplitudes were 0.77 +/- 0.50 microV for 16 degrees checks, 0.09 +/- 0.16 microV for 6.7 degrees, 0.07 +/- 0.13 microV for 3.2 degrees, and 0.08 +/- 0.09 microV for 1.6 degrees. CONCLUSIONS: It was possible to record ERGs and PERGs in pigs. However, the ERG amplitudes were small; PERG amplitudes were even smaller in both groups and cannot be reliably recorded. A problem for both ERG and PERG was the high intra-individual and interindividual variability. Therefore, only very extensive damage to the retina by vitrectomy or Er:YAG laser treatment might lead to a significant change in the ERG or PERG amplitudes.

Erbium: YAG laser ablation of retinal tissue under perfluorodecaline: determination of laser-tissue interaction in pig eyes.

PURPOSE: To evaluate the effect of Er;YAG laser on pig retina using a perfluorodecaline/retina interphase with the goal of precisely determining the extent of retinal tissue ablation. METHODS: Free running (tau = 250 microsec) Er:YAG laser pulses were transmitted through a zirconium fluoride (ZrF4) fiber guarded by quartz rod (d = 1000 microm). Laser pulses were applied to the retinal surface of enucleated pig eyes. Eyes were mounted in a specially designed rotating sample holder. The fiber probe was elevated 1.0 +/- 0.3 mm above the retinal surface with perfluorodecaline serving as transmitting medium. The laser energy was applied in a circular pattern with a radius of 3.0 mm. Radiant exposures were set to 1, 3, 5, and 10 J/cm2. RESULTS: Tissue ablation linearly increased with radiant exposure from 3.2 +/- 3.7 microm at 1 J/cm2 up to 40.9 +/- 12.9 microm at 10 J/cm2. Thermal tissue changes extended 70 +/- 10 microm vertically into the retina and 25 +/- 5 microm horizontally. Distortion of outer photoreceptor segments was noticed when the retina was exposed to radiant exposures of 3 J/cm2 or higher. CONCLUSIONS: The Er:YAG laser in combination with perfluorodecaline produced precise ablation of the pig retina, which suggests the feasibility of this technique for safe ablation of epiretinal membranes.

Evaluation of in situ fracture versus phaco chop techniques.

PURPOSE: To quantify and compare the phaco time required using in situ nucleofracture and phaco chop techniques. SETTING: Center for Research on Ocular Therapeutics and Biodevices and Miyake Laboratory, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Thirty human eyes obtained postmortem were randomly divided into 2 groups of 15 eyes each. In situ nucleofracture or phaco chop was performed in each group. The phaco time required for each technique was determined. RESULTS: The mean phaco time was 0.91 minutes +/- 0.37 (SD) for the phaco chop and 1.56 +/- 0.89 minutes for the in situ fracture technique (P < .015). CONCLUSIONS: The phaco chop technique reduced phaco time and total phaco power consumed during phacoemulsification without imposing a risk of intraoperative complications.

[Enophthalmos caused by orbital metastasis of breast carcinoma]. / Enophthalmus durch Orbitametastase eines Mamma-Carcinoms.

BACKGROUND: Orbital metastatic disease usually leads to exophthalmos but rarely to enophthalmos. We report a case of a metastasis causing enophthalmos. PATIENT: A 68-year-old woman had mastectomy for breast cancer six years prior to presentation. She complained of double vision when looking sideways. The right eye showed a motility reduction in all directions and a slight ptosis. She had 4 mm enophthalmos, and the eyelids were sunk into the orbit. There were no signs of optic nerve damage. Magnetic resonance imaging showed a retrobulbar mass surrounding the optic nerve and infiltrating the muscles. The space of the orbital fat was reduced. A biopsy confirmed the diagnosis of metastatic breast carcinoma. Histologically, the connective tissue was infiltrated by lymphocytes, and the nuclei of the tumor cells where aligned in a linear "indian file" pattern. 30% of the tumor cells contained the estrogen-receptor protein, 40% the progesterone-receptor protein. The CA-15/3 and CEA levels were elevated. The patient underwent orbital radiation with 50 Gy. During the following 2 months, the enophthalmos increased to 6 mm. DISCUSSION: We suggest the following hypothesis as the cause of enophthalmos in orbital metastases: The tumor growth goes along with fibrosis. Subsequent shrinkage of the connective tissue pulls the eye back into the orbit. The ensuing elevation of tissue pressure leads to atrophy of the retrobulbar fat. The increase of tumor volume is too slow to compensate for the fat atrophy. Slowly progressive enophthalmos with reduced motility is nearly pathognomonic of metastatic scirrhous breast carcinoma. In rare cases, a diffusely infiltrating carcinoma of the gastrointestinal tract may cause a similar picture.

Centration and fixation of posterior chamber intraocular lenses in eyes with pseudoexfoliation syndrome. An analysis of explanted autopsy eyes.

Pseudoexfoliation syndrome is an important risk factor in cataract surgery. We examined decentration of posterior chamber intraocular lenses in a series of 24 autopsy eyes with pseudoexfoliation syndrome that had undergone cataract surgery and intraocular lens implantation. The results were compared to a control group of 25 normal autopsy eyes that matched the pseudoexfoliation collection for age distribution, implant duration and further anatomical parameters. The mean lens decentration in all pseudoexfoliation eyes (0.75 +/- 0.38 mm) was significantly higher than in the control group (0.40 +/- 0.29 mm) (p = 0.0008). Analysis of subgroups with symmetrical bag/bag fixated intraocular lenses showed a significantly higher decentration in the pseudoexfoliation group (p = 0.04). The main reason for decentration was a decentration of the entire capsular bag in pseudoexfoliative eyes (p = 0.001), which was related to zonular weakness and damage. The results indicate that in patients with pseudoexfoliation syndrome alternative fixation sites, like sulcus or transscleral fixation, should also be considered.

A modified preparation technique for closed-system ocular surgery of human eyes obtained postmortem: an improved research and teaching tool.

PURPOSE: In addition to use for corneal transplantation, human autopsy eyes also are used for teaching and vision research. The valuable posterior video technique of Miyake usually is done with an "open-sky" preparation. Closed-system surgery in postmortem eyes is difficult because of postmortem decrease of corneal clarity and myosis. The authors have developed an improved preparation technique that allows closed-system ocular surgery in human postmortem eyes. METHOD: The cornea is dehydrated using a hyper osmolar (15 percent) dextran solution (Swinger-Kornmehl solution), which clarifies the cornea for several hours. The pupil is dilated mechanically by injecting dextran solution into the anterior chamber, and the iris is fixated using formaldehyde (10 percent) and Karnovsky solution. RESULTS AND CONCLUSIONS: This technique can be used in autopsy eyes up to 4 days postmortem without other fixation. Incision techniques, capsulorhexis, phacoemulsification, and intraocular lens implantation, as well as other surgical procedures such as glaucoma surgery, transcleral fixation of posterior chamber lenses and vitrectomies, can be performed. Neodymium:YAG laser capsulectomies or other laser surgical procedures are also possible. This technique is not only excellent for residency training and postgraduate wet laboratories, but is also a viable tool for research purposes.

[Suitability of polyvinylpyrrolidone (PVP) as a substance for hydrogel intraocular lenses]. / Eignung von Polyvinylpyrrolidon als Material für Hydrogelintraokularlinsen.

UNLABELLED: Conventional PMMA intraocular lenses (IOLs) have been shown to restore vision successfully after cataract surgery, but have been associated with complications such as decentration, destruction of intraocular tissue, and posterior capsule opacification. Expansile IOLs based on cross-inked polyhydroxyethylmethacrylate (PHEMA) also undergo chemically induced hydrolysis, polymer leaching and gel fragmentation. The focus of this research is to prepare and characterize hydrogel IOLs prepared from PVP using gamma-irradiation. METHODS: Hydrogels were prepared from aqueous solutions of PVP by free radical polymerization as a function of gamma-irradiation dose (0.5 x 106 to 2.5 x 106 rad), PVP concentration (4% to 16% w/v), molecular weight (MW) (10 x 103 to 360 x 103 Da), and blending with low and high MW PVP. Viscometric analysis, swelling characterization studies, and polymer leaching studies were carried out to access network formation. In addition changes in lens geometry in an animal model were measured in response to cycloplegic eyedrops. RESULTS: Cross-linking efficiency was greatest with an initial MW of 360 x 103 Da and lowest with an initial MW of 10 x 103 Da. The time to reach equilibrium from the glassy state and the degree of swelling in saline decreased with increasing gamma-irradiation dose and increased with concentration of PVP and blending of low and high MW PVP. The equilibrium water content ranged from 90 to 98% (w/w). Eighty-five percent of the equilibrium dimensions could be achieved within 90 min. Gravimetric analysis and HPLC indicate that the amount of PVP that is not incorporated into the network ranges from 0.25% to 6% (w/w). This was inversely related to the gamma-irradiation dose. The MW of the leached samples was estimated to be greater than 10 x 103 Da in all cases. CONCLUSIONS: PVP hydrogel IOLs prepared by gamma-irradiation have advantages in terms of chemical stability, high water content, and ease of preparation. They may not need further purification or sterilization prior to implantation. In addition, they may allow for accommodation. No comments can be made regarding the biocompatibility, long-term stability, or optical quality at this time.

Centration and fixation of silicone intraocular lenses: clinicopathological findings in human autopsy eyes.

PURPOSE: To analyze centration and fixation of three-piece and one-piece silicone intraocular lenses (IOLs) in human autopsy eyes. SETTING: Center for Intraocular Lens Research, Medical University of South Carolina, Charleston. METHODS: Thirty eyes among those submitted to the center between 1986 and 1994 were evaluated. The globes were sectioned at the equatorial plane and photographed from a posterior view. Gross examination was performed to determine IOL type, fixation, centration, and additional pathology. The results were compared with those of a control group of autopsy eyes implanted with one-piece and three-piece poly(methyl methacrylate) (PMMA) IOLs. The control group matched the silicone group in patient age, fixation site, and duration of implantation. RESULTS: Twenty-three eyes (79.3%) had three-piece silicone IOLs and 7 eyes (20.7%), one-piece plate IOLs. Average patient age in the three-piece group was 77.3 years +/- 6.7 (SD) and in the one-piece group, 74.3 +/- 3.8 years. The 30 IOLs were symmetrically fixated in the bag. Average decentration of the three-piece and one-piece IOLs did not differ significantly, 0.37 +/- 0.31 mm and 0.26 +/- 0.13 mm, respectively (P = .37). There was also no significant difference in decentration between the silicone groups and the PMMA groups (P = .93). CONCLUSION: Centration and fixation of silicone IOLs were equivalent to those of standard PMMA IOLs.

[Centering the posterior chamber lens in autopsy eyes with and without pseudoexfoliation syndrome]. / Hinterkammerlinsenzentrierung in Autopsieaugen mit und ohne Pseudoexfoliationssyndrom.

The pseudoexfoliation syndrome (PEX) is an important risk factor for cataract surgery. In this study we examined a series of 24 autopsy eyes with PEX that had undergone cataract surgery and intraocular lens (IOL) implantation. The eyes were grossed for IOL fixation and centration. The results were compared to a control group of 25 non-PEX autopsy eyes that matched the PEX series in age distribution, implant duration and anatomical parameters (i.e., axial length) (P > 0.18). The mean IOL decentration in all PEX eyes (0.75 +/- 0.38 mm) was significantly higher than in the control group (0.40 +/- 0.29 mm) (P = 0.0008). Analysis of subgroups with symmetrical bag/bag fixated IOLs also showed significant higher decentration in the PEX group (P = 0.04). The main reason for decentration was decentration of the entire capsular bag in the PEX eyes (0.28 +/- 0.19 vs 0.10 +/- 0.16 in controls; P = 0.001). Patients with PEX showed a higher amount of IOL decentration. The results indicate that the insufficient suspension apparatus of the lens and decentration of the entire capsular bag are the main reasons for IOL decentration in patients with PEX.

Analysis of 100 explanted one-piece and three-piece silicone intraocular lenses.

PURPOSE: The authors analyzed incidence and types of complications seen after implantation of silicone posterior chamber intraocular lenses (PC IOLs). These data were compared with those obtained in previous studies with standard polymethylmethacrylate IOLs. METHODS: Data from the laboratory database were collected on 100 explanted silicone IOLs submitted to the Center for Intraocular Lens Research from 1986 to 1994. RESULTS: Of the 100 IOLs, 63 were three-piece designs with polypropylene loops and 37 were one-piece plate lenses. The two most important reasons for explantation were IOL decentration (42.0%) and inflammation (27.7%). There was no significant difference for the reasons of explantations between one- and three piece IOLs (P > 0.1). Intraocular lenses that had been removed due to inflammatory reactions had a significantly longer implant duration (19.2 +/- 18.9 months) than lenses that were explanted because of decentration (9.19 +/- 12.1 months) (P = 0.018). CONCLUSIONS: The results presented here showed that there is no substantial difference between these IOLs and polymethylmethacrylate lenses in terms of reasons for explantation. The authors' data suggest that clinical outcome is not as dependent on the type of lens selected as it is on the quality of surgery. The key to good results is the use of "capsular surgery," namely techniques that ensure secure in-the-bag IOL fixation.

[No-stitch tunnel incision vs. corneoscleral incision. A prospective, randomized study]. / No-stitch-Tunnelinzision vs. korneosklerale Inzision. Eine prospektive, randomisierte Studie.

An important factor in early visual recovery after cataract surgery is surgically induced astigmatism. In a randomized clinical trial we compared the development of astigmatism and visual acuity after three different types of incision and suture techniques. Sixty-seven patients were randomized into three groups: (a) scleral tunnel incision (5 mm) without suture (no stitch) (n = 23) (b) scleral tunnel incision (5 mm) with suture (single stitch) (n = 23) (c) corneoscleral incision (5 mm) with suture (CS suture) (n = 21). Implants: 5 mm optic size; follow-up period: 6 months. There was no statistically significant difference among the 3 groups concerning age distribution and preoperative astigmatism. Postoperative follow-up at day 1, weeks 1, 2, months 1, 4 and 6 showed astigmatic values ranging from 0.84 to 1.41 D (means values, vector analysis; differences not significant: P > 0.10). The surgically induced astigmatism ranged from 1.13-1.74 D (differences not significant P > 0.16). At all follow-up dates the mean uncorrected distance acuity did not differ significantly among the three groups (P > 0.35). No quantitative statistically significant differences could be detected among the three incision and suture techniques.

Are there acceptable anterior chamber intraocular lenses for clinical use in the 1990s? An analysis of 4104 explanted anterior chamber intraocular lenses.

PURPOSE: The authors pose the question as to whether there are any anterior chamber intraocular lenses (AC IOLs) acceptable for clinical use in the 1990s. METHODS: Data on the incidence and types of complications of 4104 AC IOLs that were submitted to the Center for IOL Research from 1982 to 1993 were retrieved from the laboratory database and analyzed using cumulative frequency calculations and the chi-square test. Normalized explantation rates were related to implantation rates that were derived from market-share analysis. RESULTS: Of 4104 explanted IOLs, 50% were closed-loop designs (n = 2095/4104); 26% (1100/4104) were miscellaneous, older designs; and 22% (919/4104) were open-loop lenses. The most important complications were corneal pathology (2065/4104) and inflammation (1370/4104). Closed-loop designs were responsible for almost 80% of corneal pathology, with an increasing complication rate with ongoing implant duration (P < 0.0001). Open-loop AC IOLs showed, in relation to their normalized rate of implantation, a significantly lower rate of complications and explantations (P < 0.01). CONCLUSION: Complication rates of flexible, open-loop AC IOLs are much lower than previously assumed. They should be distinguished clearly from most older AC IOL designs. Consideration of these lenses as an alternative to sutured posterior chamber IOLs for secondary or exchange implantation may be warranted for selected clinical indications. They also could provide an alternative to the aphakic spectacle rehabilitation program in developing countries, which will have a positive impact on the overwhelming backlog of patients with cataract in the underprivileged world.

[Area of contact of the artificial lens and posterior capsule. Systematic study of various haptic parameters]. / Kontaktbereich von Kunstlinse und Hinterkapsel. Systematische Untersuchung unterschiedlicher Haptikparameter.

New techniques in cataract surgery, namely the small and tunnel incisions, have led to intraocular lens (IOL) designs with haptics angulated anteriorly as low as 0 degrees. Clinical and animal studies strongly support the inhibitory influence of contact between the optic and the posterior capsule on the formation of posterior capsular opacification. Human cadaver eyes were used to examine the effect of different haptic angulations (1 degree, 5 degrees, 10 degrees, 15 degrees), different haptic diameters (11.5 mm, 12.0 mm, 12.5 mm), and different optic diameters (5.0 mm, 6.0 mm) on the area of contact between optic and posterior capsule. Exciting fluorescein with a Wood light visualized the space between the IOL and the posterior capsule. Only IOLs with haptics bent forward at more than 10 degrees could achieve contact between IOL and posterior capsule. The haptic and optic diameters had only a limited effect.

Neodymium:YAG laser damage on silicone intraocular lenses. A comparison of lesions on explanted lenses and experimentally produced lesions.

In this study we examined 17 explanted silicone intraocular lenses (IOLs) (two one-piece, 15 three-piece) that had evidence of neodymium:YAG (Nd:YAG) laser damage. The majority of lenses (47.1%) had been explanted because of persistent pigment deposits and chronic inflammation. Decentration or IOL dislocation had occurred with 29.4% of lenses. All 17 patients had had Nd:YAG laser posterior capsulectomy, anterior surface polishing, or both; treatments ranged from one to 13 times. By both clinical and gross examination, the laser lesions appeared dark. This was misinterpreted by some opthalmologists as pigment deposits and some patients had additional Nd:YAG laser treatment, which increased the severity of the laser damage. The mean depth of laser damage on the IOLs was 143 +/- 113.4 microns. It was between 51 and 175 microns in approximately 61.0% and deeper than 300 microns (maximum 660 microns) in 9.3%. We compared the explanted IOLs with silicone IOLs that were experimentally damaged using standard power levels from 0.3 to 3.0 mJ and different focal areas. The appearance of the experimentally induced laser burns was equivalent to that on the explanted IOLs, especially the dark laser pits. Since the laser lesions may resemble pigment deposits on slitlamp examination, we recommend careful examination of patients prior to planned laser therapy.

[Night driving capacity of pseudophakic patients]. / Nachtfahrtauglichkeit pseudophaker Patienten.

One hundred pseudophakic patients (aged 62.1 +/- 10.8 years) were examined for glare sensitivity and contrast vision, using the Mesoptometer II, 15.8 +/- 9.8 months after implantation of monofocal intraocular lenses. The patients were tested in order to determine whether they met the requirements of the German Ophthalmological Society (DOG) for the granting of a driver's license. The patients were divided into three groups: (1) pseudophakic bilaterally (n = 50), (2) pseudophakic in one eye with phakic contralateral eye (n = 25), and (3) pseudophakic in one eye with cataract in contralateral eye (n = 25). There were no differences between the groups in corrected distance acuity (ANOVA, P = 0.17). Fifty-two percent of the patients did not fulfill the requirements of the DOG (group 1 50%, group 2 24%, group 3 84%). In groups 1 and 2 the binocular results for glare sensitivity and contrast vision were significantly better than the monocular results (P < 0.001). In group 3, however, there was no difference between binocular and monocular results (P > 0.3). In 20% of patients in this group the binocular results were worse than the monocular results. Results for both contrast vision and glare sensitivity were significantly related to age. Overall, this population of pseudophakic patients were 40-50% less suited to night driving than were healthy volunteers with normal eyes.

[Reasons for the explantation of posterior chamber lenses]. / Gründe für die Explantation von Hinterkammerlinsen.

In this study we analysed the overall incidence and the types of complications seen after cataract surgery and implantation of posterior chamber intraocular lenses (PC-IOLs) based on a review of 1460 explanted PC-IOLs. Of these explanted PC-IOLs, 1072 (73.4%) were three-piece PMMA IOLs with Prolene haptics, 261 (17.9%) were one-piece all-PMMA IOLs, 81 (5.6%) were silicone IOLs and 46 (3.1%) were of various other designs (multifocal IOLs, disc IOLs etc.). The mean implant duration for all IOLs was 25.57 +/- 29.24 months. The two most important reasons for explantation were IOL decentration (622/1460, 42.6%) and inflammation (347/1460, 23.77%). There was no difference in reasons for explantation between one-piece and three-piece IOLs. Operative techniques such as "can opener" capsulotomy and sulcus fixation have more influence on IOL decentration than the IOL design alone. Modern operative techniques such as continuous curvilinear capsulorhexis, phacoemulsification and symmetrical in-the-bag fixation of "capsular IOLs" should decrease the explantation and complication rate in the future.

[Complications after implantation of anterior chamber lenses. An analysis of 4,100 explanted intraocular lenses]. / Komplikationen nach Vorderkammerlinsenimplantation. Eine Analyse von 4100 explantierten Intraokularlinsen.

In this study we analyzed the incidence and types of complications seen after cataract surgery and implantation of anterior chamber intraocular lenses (AS-IOLs). This report is based on a review of 4104 explanted AC-IOLs that were submitted to the Center for IOL Research over the past 10 years. The results from pathological examinations were correlated with clinical information. Of the 4104 IOLs, 50% were closed-loop designs (n = 2095/4104), and 22% were open-loop lenses (919/4104). The IOLs most frequently explanted were the closed loop designs Leiske (n = 847) and Stableflex (n = 808). The most important reason for explantation was corneal pathology. Closed-loop IOLs had a much higher complication rate than open-loop lenses. Flexible open-loop AC-IOLs showed the highest explantation rate during the first postoperative year due to surgical problems. The complication rate of closed-loop AC-IOLs increased with implant duration and were responsible for 80% of the corneal pathology. Flexible open-loop AC-IOLs can be an alternative for secondary or exchange implantation. Furthermore, they could also be a viable alternative for cataract surgery in developing countries in order to help catch up with the overwhelming backlog of cases that exist there.

[Capsulorhexis technique in pediatric cataract. Presented in the rabbit model]. / Kapsulorhexistechnik bei kindlicher Katarakt. Dargestellt am Kaninchenmodell.

Continuous curvilinear capsulorhexis (CCC) has become a standard procedure in cataract surgery. In pediatric cataracts, however, this technique is difficult to perform. Because of the elasticity and tension of the pediatric anterior lens capsule the danger of radial tears is high. Similar conditions are found in the rabbit model. The anterior lens capsule of young albino rabbits is very elastic. We have developed a CCC technique in rabbits that allows a controlled round capsular opening. This technique was used in an experimental study with 16 rabbits (32 eyes). The mean capsulorhexis diameter was 4.9 +/- 0.9 mm. A radial tear occurred in only 2/32 cases. The technique permits a controlled circular anterior capsulectomy for capsules with high surface tension and elastic properties. This can readily be applied to human pediatric cases.