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PubMed1995

[Anatomical evaluation of the anterior capsular zonular free zone in the human crystalline lens (age range, 50 approximately 100 years)].

It is important to determine the anterior capsular zonular free zone (ZFZ) in order to minimize the risk of zonular disinsertion. From this point of view the size of the ZFZ of normal suspended lenses was directly measured in 199 human eyes obtained postmortem. The cornea was completely excised and the iris removed to allow clear visualization of the anterior surface of the lens to the equator. After measuring lens diameter with a caliper, a 4 mm continuous curvilinear capsulorhexis was performed, and lens substrate was completely removed by phacoemulsification. Care was taken to minimize trauma to the zonules during surgery. The anterior insertion of the zonules was identified at high power magnification; the size of the ZFZ was measured with a caliper. The mean age was 75.5 +/- 10.3 (+/-SD) years (age range, 50 approximately 100 years). The mean diameter of the lenses was 9.72 +/- 0.31 mm. The mean diameter of the ZFZ was 6.83 +/- 0.35 mm. Statistical analysis revealed no significant correlation between the size of the ZFZ and age, or between the size of the ZFZ and lens diameter. The present study indicates that the size of the ZFZ was constant regardless of age or lens diameter.

Aged↗
PubMed1996

A study of human lens cell growth in vitro. A model for posterior capsule opacification.

PURPOSE: After intraocular lens (IOL) implant surgery for cataract, cell growth on the posterior capsule is responsible for renewed visual impairment in approximately 30% of patients. The authors have, therefore, developed a human lens capsule system to study this growth in vitro. METHODS: Sham cataract surgery, including anterior capsulorhexis, nucleus hydroexpression, and aspiration of lens fibers, was performed on donor eyes. In some cases, a polymethylmethacrylate IOL implant was placed in the capsular bag. The capsular bag was dissected free, pinned flat on a plastic culture dish, covered with Eagle's minimum essential medium supplemented with 10% fetal calf serum and observed by phase-contrast and dark-field microscopy for as long as 100 days. At the end-point, capsules were examined by fluorescence microscopy for actin, vimentin, and chromatin. RESULTS: Within 24 hours, there was evidence of cell growth in the equatorial region. After 2 to 3 days, cells were normally observed growing from the rhexis onto the posterior capsule and across the anterior surface of the IOL, if present. Growth proceeded rapidly so that the posterior capsule, for example, was totally covered by a confluent monolayer of cells at 5.8 +/- 0.6 days and 7.2 +/- 0.7 days for capsules aged < 40 years and > 60 years, respectively. Total cover of the anterior IOL surface generally followed 4 to 5 days behind that of the capsule. Capsular wrinkles became increasingly apparent as time progressed, causing a marked rise in light scatter. An increase in capsular tension also occurred, and the actin filaments became more polarized near the wrinkles. CONCLUSIONS: The model presented here for posterior capsule opacification shows many of the changes seen in vivo, including rapid lens cell growth, wrinkling, tensioning, and light scatter in the posterior capsule. It will be possible to develop strategies for inhibiting cell growth with this system.

Actins↗
PubMed1996

Cataract extraction and intraocular lens implantation with anterior vitrectomy in children.

OBJECTIVE: Extracapsular cataract extraction (ECCE) with selective intraocular lens (IOL) implantation has been the choice of the treatment for children with cataracts. With regard to surgical technique, ECCE with anterior segment vitrectomy has shown some success in reducing complications. Formation of a secondary membrane and opacity of the posterior capsule, however, are still major postoperative complications. To reduce these complications, we modified current surgical procedures with minimal incisions and manipulations. PATIENTS AND METHODS: ECCE with anterior segment vitrectomy was performed using Storz Protage's system in 84 eyes of 58 children ranging in age from 14 months to 14 years. Of 70 eyes of children aged above 3 years, IOLs were implanted simultaneously. Vision improvement and incidence of postoperative complications were compared with other standard procedures to determine the benefits of the operation for children with cataracts. After the anterior capsule was opened by continuous circular capsulorhexis or envelope-form capsulectomy, the lens cortex was excised. Subsequently, the IOL was implanted into the bag. RESULTS: Nine-30 months follow-up showed that all of the central area of the posterior capsule remained clear except one eye in which a secondary membrane was partially formed on the anterior surface of vitreous. No other operative or postoperative complications occurred. CONCLUSIONS: The results indicate that the modified procedure is beneficial in the prevention of secondary cataract formation and other postoperative complications in a short term follow-up, however, a long-term follow-up is warranted to evaluate its role in pediatric cataract surgery.

Adolescent↗
PubMed1996

[Viscoexpression of the lens nucleus in extracapsular cataract extraction].

The author rates the frequency of peroperative complications during cataract extraction performed by continuous curvilinear capsulorhexis (CCC) and viscoexpression technique. The total number was 369 cases, the peroperative complication was noted in 8.1% cases. The relaxing incision of anterior capsule was noted in 17.1% of cases. The most frequent complication in cases without relaxing incision (82.9%) was asymetric implantation of IOL (sulcus-bag, 2.6%). In cases with relaxing incision (17.1%) the most frequent complication was posterior capsule rupture with subsequent anterior vitrectomy (7.9% from total of 17.1%).

Cataract Extraction↗
PubMed1996

[Experimental experiences with balloon-shaped capsular sac implantation with reference to accommodation outcome in intraocular lenses].

Implantation of a balloon into the capsular bag theoretically allows the injection of fluid materials for lens replacement, thus enabling accommodation. Leakage of the fluid can be avoided in this way, and a large variety of potential materials can be tested without taking into account their effect on ocular tissue. We tested ellipsoid balloons made of polydimethylsiloxane. The balloons had a maximum diameter of 11.0 mm and a wall thickness of 0.15 mm. After capsulorhexis of 2.5 mm and phacoemulsification, the balloons were implanted in enucleated pig eyes and filled with 2% methylcellulose or silicone oil through little tubes on the anterior side. Implantation of the balloons into the capsular sac was much more difficult than normal IOL implantation into the posterior chamber. We had to enlarge the tunnel incision to 4.5 mm, and it was technically difficult to leave the relatively strong capsule of the pig intact during implantation. Due to the additional surfaces we found increased reflection. Because of the difficulties described we cannot see any advantages over other refilling techniques.

Animals↗
PubMed1996

[Cataract extraction by phacoemulsification using in situ nuclear fracture technique].

OBJECTIVE: The study was designed to investigate the technique of phacoemulsification in which the lens nucleus is fractured without collapse of nucleus into anterior chamber. METHODS: Phacoemulsification using in situ nuclear fracture technique with posterior chamber intraocular lens implantation was performed on 55 eyes of 52 patients with senile cataract. RESULTS: The in situ nuclear fracture technique was successfully completed in 92.72% of all the eyes: the average time of lens phacoemulsification was 2.26 minutes, the rate of vitreous loss was 5.46%, the rate of corneal endothelial cell loss was 12.13%, and one week after the operation, the visual acuities of 0.5 or better were obtained in 72.72% of the cases. CONCLUSION: The key points of in situ fracture technique by phacoemulsification include selection of softer nucleus, continuous ring-shaped capsulorhexis, complete hydrodissection and fracture of the nucleus quadrant by quadrant.

Aged↗
PubMed1997

Retrospective comparison of techniques to prevent secondary cataract formation after posterior chamber intraocular lens implantation in infants and children.

PURPOSE: To determine the effect of various methods of managing the posterior capsule and anterior vitreous on the rate of posterior capsule opacification in pediatric eyes implanted with posterior chamber intraocular lenses (PC IOLs). SETTING: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. METHODS: We reviewed the charts of 20 eyes of 15 children (aged 1.5 to 2 years) who had primary cataract surgery with PC IOL implantation during the past 5 years. The posterior capsule and anterior vitreous were managed in a variety of ways: In 5 eyes, the posterior capsule was left intact; in 15 eyes, a posterior continuous curvilinear capsulorhexis (PCCC) was performed - 6 with and 9 without anterior vitrectomy; in 8 eyes, posterior optic capture was performed - 3 with and 5 without vitrectomy. The follow-up ranged from 1 to 4.5 years (mean 2 years). RESULTS: Visually significant secondary cataract developed in the five eyes with intact posterior capsules and in the four eyes that had PCCC without vitrectomy and without posterior optic capture (i.e., the optic was left in the capsular bag). The optical axis remained clear in the six eyes that had PC IOL implantation with vitrectomy (with or without posterior optic capture). Initially, all eyes that had optic capture without vitrectomy also remained clear, but after 6 months, four of five developed opacification. CONCLUSION: In this series, PCCC with anterior vitrectomy was the only effective method of preventing or delaying secondary cataract formation in infants and children.

Cataract↗
PubMed1997

Mechanisms of acute intraocular pressure increases after phacoemulsification lens extraction in dogs.

OBJECTIVE: To investigate the mechanisms by which intraocular pressure (IOP) increases acutely after phacoemulsification (PE) lens extraction in clinically normal dogs. ANIMALS: 24 young adult dogs. PROCEDURE: Intraocular pressure was monitored for up to 24 hours after unilateral intercapsular PE in 17 clinically normal, adult dogs. In 8 of these dogs, use of 2% hydroxypropyl methylcellulose (HPMC) aided capsulorhexis. Mean volume of irrigation, PE time, and power were constant between groups. After surgery, dogs were randomized then euthanatized, and eyes were examined grossly and histologically at 0 (n = 4), 3 (n = 7), and 24 hours (n = 6) after PE. Seven additional dogs underwent anterior chamber decompression alone (n = 4) or served as morphologic controls (n = 3). RESULTS: Intraocular pressure peaked by postoperative hour 3 at 49.9 +/- 5.0 mm of Hg and normalized by 24 hours. Use of HPMC did not affect the peak or duration of IOP increase. Blood refluxed into the collecting channels and corneoscleral trabecular meshwork in operated eyes. Computer-aided morphologic analysis indicated significant (P < 0.001) reduction in ciliary cleft cross-sectional surface area and width immediately after PE, but not after anterior chamber decompression alone. Cleft collapse was significantly (P < 0.02) greater at 24 than at 3 hours, despite return of IOP to control values by 24 hours. Plasmoid aqueous also was found in the meshwork. CONCLUSIONS AND CLINICAL RELEVANCE: Sudden, large increases in IOP with few overt clinical signs may occur immediately after lens extraction in dogs. Such increases risk compromising the corneal incision and may damage the optic nerve, thereby complicating lens extraction. Structural alterations in the trabecular meshwork persist after IOP has normalized in 24 hours and may contribute to genesis of glaucoma in the late postoperative period.

Analysis of Variance↗
PubMed1997

[Contemporary opinions on intraocular lens implantation in children].

The purpose of the paper is a presentation of contemporary opinions about IOL implantation in children based on literature and own 11-years-long experience in this field. IOLs are implanted into the bag in children aged from 2 years. Removal of the central part of posterior capsule by capsulorhexis and anterior vitrectomy through posterior capsule hole is performed before implantation.

Child↗
PubMed1998

[Current status of cataract surgery. Modern methods--internal medicine risk factors and contraindications].

Modern cataract surgery is characterized by minimal invasive techniques that have been introduced during the past decade. These include phacoemulsification, capsulorhexis, foldable intraocular lenses and small tunnel incisions. High success rates coupled with low complication rates have resulted in a change in indications--cataract surgery is no longer performed merely to prevent blindness, but also to improve vision in patients whose professional or private visual demands are compromised by the onset of lens opacification. To ensure that their cooperation with the ophthalmic surgeon results in optimal benefit to the patient, it is important for general practitioners and internists to be conversant with the risk factors and contraindications for cataract surgery.

Aged↗
PubMed1998

A simple, cost-effective method for practicing phacoemulsification in the cadaveric eye.

The authors describe an inexpensive, reliable method for practicing intraocular surgery using a rigid contact lens as a temporary keratoprosthesis. This method allows clear visualization of the anterior chamber and lenticular structures for practicing modern cataract surgery, including capsulorhexis, hydrodissection, phacoemulsification, cortical aspiration, and intraocular lens insertion.

Cadaver↗
PubMed1997

[Immunolabelling of collagen types I, III and IV, laminin and fibronectin in the human lens capsule].

PURPOSE: To localize collagen types I, III, and IV, laminin and fibronectin in the anterior human lens capsule. MATERIAL AND METHODS: Twenty-one anterior capsules were sampled by capsulorhexis during extracapsular cataract extraction (mean age 71.5). All capsules were labelled by an immunostaining specific for each antibodies. Immunostaining of four capsules was revealed with immunoperoxydase and seventeen using indirect immunofluorescence. RESULTS: Labelling of collagen types I and III was observed throughout the entire thickness of the capsule for each technique, the strongest labelling was found in the base of the epithelial cells with immunofluorescence. Collagen type IV was observed at the base of the epithelial cells whichever technique was used. Laminin could be detected in the inner layer of the capsule, using immunoperoxydase or immunofluorescence. No specific labelling was found for fibronectin using the two techniques. CONCLUSIONS: Different kinds of collagens have been found in capsules, more particularly the type III. The latter does not appear on other ocular basement membrane. Because of this uneven distribution in the capsule's thickness, each collagen might have a specific function.

Aged↗
PubMed1998

[Reduction of astigmatism by 4mm long sutureless corneal cataract incision (stretch incision) with phacoemulsification and 5mm PMMA lens implantation].

AIM: Refractive cataract surgery using corneal incisions is aiming at neutralization of preoperative astigmatism. PATIENTS AND METHODS: 61 patients with preoperative astigmatism of 2.25 +/- 0.98 were included in the treatment. A self-sealing corneal tunnel incision measuring 4.0 to 4.1 mm in external diameter and 6.5 to 7.0 mm in internal diameter (stretch incision) was performed on the steeper axis. After capsulorhexis and phacoemulsification a 5 mm PMMA lens was implanted without suturing. Keratometry and corneal topography were performed preoperatively, 3 days and 1 year respectively following surgery. The statistical analysis was based on the Wilcoxon signed ranks test. RESULTS: Surgical induced astigmatism (IA) following superior incisions in cases of astigmatism with the rule (n = 29) amounted to 1.93 +/- 0.97, while lateral incisions in cases of astigmatism against the rule (n = 29) led to an IA of 1.35 +/- 0.73. Axial shifts by more than 30 degrees were 23% following superior incisions and 17%, after lateral incisions. We observed. astigmatic reduction of 1.3 D after superior incisions and 0.7 D following lateral incisions. CONCLUSION: By 4 mm corneal cataract incisions on the steeper axis a high preoperative astigmatism can be reduced significantly without additional keratotomies.

Astigmatism↗
PubMed1998

[Intracameral lidocaine and phacoemulsification under topical anesthesia. Apropos of 80 operations].

PURPOSE: To evaluate the advantage of intracameral unpreserved lidocaine for patient comfort during phacoemulsification under topical anesthesia. METHODS: In this prospective study, we performed 80 phacoemulsifications under topical anesthesia, with tetracaine 1% drops, 10 minutes before and at the start of surgery: 40 patients received 0.3 cc balanced salt solution (BSS) intracameral injection; 40 patients received 0.3 cc unpreserved lidocaine 1% intracameral injection. The same surgical procedure was performed in both groups: 3.2 mm temporal corneal self-sealing incision, capsulorhexis, foldable polyHEMA IOL implantation into the capsular bag. There was no intravenous sedation. RESULTS: Forty-eight percent (19) in the BSS group and 70% (28) in the lidocaine group felt no pain. 10% (4) in the BSS group reported sharp pain during phacoemulsification. During IOL insertion, no pain was reported by 48% (19) in the BSS group, and 75% (30) in the lidocaine group; 10% (4) in the BSS group felt severe pain (significant difference: p < 0.05). Endothelial cell loss was 6% in the BSS group, and 6.4% in the lidocaine group (non significant difference). CONCLUSION: Intracameral lidocaine is safe and effective in decreasing discomfort among patients undergoing phacoemulsification under topical anesthesia.

Administration, Topical↗
PubMed1998

Quantitative comparison of posterior capsule opacification after polymethylmethacrylate, silicone, and soft acrylic intraocular lens implantation.

OBJECTIVE: To quantitatively compare the extent of posterior capsule opacification (PCO) after polymethylmethacrylate (PMMA), silicone, and soft acrylic intraocular lens implantation. PATIENTS AND METHODS: A total of 240 eyes from 240 patients undergoing implant surgery were randomized into 3 groups based on the type of lens implanted: PMMA, silicone, and soft acrylic. The density value of PCO in 185 eyes was quantitated approximately 2 years after surgery by a new measurement method using the Scheimpflug videophotography system. RESULTS: Twenty-one eyes (30.4%) in the PMMA group, 4 (5.7%) in the silicone group, and 2 (2.7%) in the acrylic group had already undergone Nd:YAG laser posterior capsulotomy. The mean +/- SD PCO values were 26.3 +/- 12.2 computer-compatible tape steps (CCT) in the PMMA group, 12.0 +/- 8.3 CCT in the silicone group, and 16.0 +/- 10.3 CCT in the acrylic group. The PCO value in the PMMA group was significantly greater than that in the silicone or acrylic group (P < .001). The visual acuity loss in the PMMA group was also greater than that in the silicone or acrylic group (P < .001). CONCLUSION: Based on the PCO value and capsulotomy rate, the PCO was more extensive with the PMMA lens than with either the silicone or soft acrylic lens, which led to visual acuity loss.

Acrylic Resins↗
PubMed1998

Staining of the lens capsule for circular continuous capsulorrhexis in eyes with white cataract.

We have developed a technique of staining the anterior capsule with a solution of indocyanine green that facilitates performance of the circular continuous capsulorrhexis in eyes with a mature cataract. We compared the results of phacoemulsification and intraocular lens implantation in 10 eyes with the capsule stained with results of 10 eyes having the same procedure with standard circular continuous capsulorrhexis. The results of specular microscopy and laser flare-cell photometry showed no statistically significant differences between the 2 groups. Although the safety of intraocular indocyanine green dye has not yet been definitively established, the findings of this pilot study suggest that it is safe and useful in visualizing the anterior capsule of a mature cataract during cataract surgery.

Aged↗
PubMed1999

Pseudocapsulorrhexis in a patient with iridocorneal endothelial syndrome.

We describe a patient with Chandler's syndrome variant of the iridocorneal endothelial syndrome in whom ectopic Descemet's membrane was found intraoperatively on the anterior surface of the lens. Initially, the membrane was confused with the anterior lens capsule during extracapsular cataract extraction, leading to the performance of a pseudocapsulorrhexis. Electron microscopy disclosed that the epilenticular membrane was composed of multiple layers of abnormal basement membrane consistent with the iridocorneal endothelial syndrome.

Aged↗