Water-mediated lysis of lens epithelial cells attached to lens capsule

LONG-TERM SURGICAL OUTCOMES OF LENS CAPSULAR FLAP TRANSPLANTATION IN THE MANAGEMENT OF REFRACTORY MACULAR HOLE

PURPOSE

To report long-term surgical outcomes of autologous and allogenic lens capsular flap transplantation (LCFT) in refractory macular hole (MH) treatment.

METHODS

Fifty consecutive eyes with refractory MH who received LCFT were reviewed retrospectively. Twelve eyes underwent autologous LCFT (LCF obtained from the same eye in 7 eyes and the fellow eye in 5 eyes) and 38 eyes with allogenic LCFT. All eyes underwent complete vitrectomy, internal limiting membrane peeling if not peeled, LCF transplantation, and 15% perfluoropropane tamponade. Simultaneous autologus whole-blood application was applied in 31 eyes to reduce LCF dislocation. The patients maintained a facedown position for 2 weeks postoperatively. Demographic information, functional results, and structural changes were evaluated.

RESULTS

The mean preoperative MH diameter was 1,102.00 µm ± 561.63 µm. The mean follow-up duration was 18.50 months ± 6.05 months (range, 12.0-38.9 months). The MH was completely closed in 48 eyes (96.00%) (18 eyes receiving autologous LCFT and 30 receiving allogenic LCFT). There are no differences of age, previous MH surgery times, MH diameter, preoperative and postoperative best-corrected visual acuity, and closure rate between the subgroups. The median visual acuity improved from 1.78 (interquartile range, 1.28-1.85) logarithm of the minimum angle of resolution (median Snellen acuity: 20/1,200) preoperatively to 1.00 (interquartile range, 0.90-1.70) logarithm of the minimum angle of resolution (median Snellen acuity: 20/200) (P < 0.01) in all patients.

CONCLUSION

Both autologous and allogenic LCFT application may provide anatomical and visual improvements in refractory MH cases. Blood application can be applied in selected cases to reduce LCF dislocation. LCFT can be performed as first-line treatment for refractory MHs.

Osmotically induced removal of lens epithelial cells to prevent PCO after pediatric cataract surgery: Pilot study to assess feasibility

PURPOSE

Development of an osmotic-shock technique to remove human lens epithelial cells (LECs) as a preventive measure to address posterior capsule opacification (PCO) after pediatric cataract surgery.

SETTING

Department of Genetics, UCL Institute of Ophthalmology, London, England, and Department of Ophthalmology, Ruijin Hospital, Jiao Tong University, Shanghai, China.

DESIGN

Laboratory study.

METHODS

Various tissue preparations of human LECs (cultured on coverslips/collagen-coated membrane inserts, human lens capsule biopsies, and lens organ cultured PCO models) were subjected to a single or incremental hyperosmotic shock (NaCl, 350-4000 mOsm/L) in the presence of inhibitors of the Na+-K+-2Cl- cotransporter (NKCC) (to disable the regulatory volume increase [RVI] process). The integrity of the cell monolayer was determined by phase-contrast microscopy, viability assays, and measurement of transepithelial resistance.

RESULTS

Hyperosmotic shock (400 mOsm/L) caused rapid cell shrinkage (<5 minutes) in all the LEC models studied. In the absence of the NKCC inhibitor, the shrunk cells gradually returned to their original cell volume and architecture over time, while still exposed to the hyperosmotic shock. However, inhibition of the RVI process disabled the ability for restoration of cell volume leading to persistent cell shrinkage, subsequently resulting in cell detachment from the underlying support medium.

CONCLUSION

Hyperosmotic shock in the presence of inhibitors of the RVI process was effective in rapidly detaching LECs from their basement membranes. This technique could potentially facilitate removal of residual LECs left on the lens capsule after cataract surgery, thus decreasing or eliminating the risk for aggressive cell proliferation and the development of PCO.

Prevention of posterior capsule opacification through intracapsular hydrogen peroxide or distilled water treatment in human donor tissue

In order to determine whether posterior capsule opacification after cataract surgery, could be delayed or inhibited through the application of hydrogen peroxide (H₂O₂) or distilled water (H₂Od),we extracted lens capsules from 25 human donor eye globes. Samples were treated for 5 min with either 30 mM H₂O₂ or H₂Od or used as controls, and cultured for one month, during which dark field and tilt illumination photos were taken. These were used to observe and quantify, time until cellular growth and confluence on the posterior capsule. After culture, histological sections were stained for H&E, α-SMA, Ki-67 and vimentin and evaluated. We prevented cellular growth in 50% of H₂Od and 58% H₂O₂ of treated samples. The overall prevention of cell growth compared to cultured controls was significant for both treatments while there was no significant difference between them. In the cases where cellular growth was not prevented, both treatments significantly delay cellular growth. Until day 28 none of the treated samples of either type that had shown growth reached total confluence. All cultured controls reached total confluence before treated samples (median = day 11.5). Also, histologically, there was a clear morphological difference between cultured controls and treated samples.

AIR/FLUID-DROPPING TECHNIQUE FOR INTRACAPSULAR DISTILLED WATER APPLICATION: A Vitrectomy Approach for Selective Targeting of Lens Epithelial Cells

PURPOSE

We describe a simplified technique of intracapsular distilled water application for targeting lens epithelial cells using vitrectomy approach of fluid-air exchange and to evaluate the reliability and safety of this technique.

METHODS

Consecutive patients with cataract were randomly assigned to treatment group and control group. After the nucleus removal and cortical aspiration, the space of anterior chamber and capsular bag were maintained with continuous infusion of sterile air by using fluid-air exchange technique through side-port incision. Distilled water was dropped into the capsular bag using a specially designed syringe. A concave air-fluid surface (a physical phenomenon) insured the contact of distilled water with the inner surface of the capsule without overflowing from the bag. The distilled water remained in place for 3 minutes and was then removed by the syringe.

RESULTS

No intraoperative surgical complication was observed, and no damage to adjacent intraocular structures was observed during the postoperative follow-up. There was no statistical difference of corneal endothelial cell loss between the treatment group and the control group. Histological study confirmed damage to the lens epithelial cells from anterior capsular specimens treated by the technique.

CONCLUSION

The simplified technique using vitrectomy approach is safe and specific for targeting lens epithelial cells without associated complications.

Prevention of posterior capsular opacification

Posterior capsular opacification (PCO) is a common complication of cataract surgery. The development of PCO is due to a combination of the processes of proliferation, migration, and transdifferentiation of residual lens epithelial cells (LECs) on the lens capsule. In the past decades, various forms of PCO prevention have been examined, including adjustments of techniques and intraocular lens materials, pharmacological treatments, and prevention by interfering with biological processes in LECs. The only method so far that seems effective is the implantation of an intraocular lens with sharp edged optics to mechanically prevent PCO formation. In this review, current knowledge of the prevention of PCO will be described. We illustrate the biological pathways underlying PCO formation and the various approaches to interfere with the biological processes to prevent PCO. In this type of prevention, the use of nanotechnological advances can play a role.

Sealed-capsule irrigation with distilled deionized water to prevent posterior capsule opacification--prospective, randomized clinical trial

PURPOSE

To evaluate the efficacy and safety of sealed-capsule irrigation (SCI) using distilled water (DW) to prevent posterior capsule opacification (PCO).

MATERIALS AND METHODS

Phacoemulsification was performed in 60 patients. Patients were randomly selected into groups. In the control the capsular bag was mechanically cleaned (MC), in the DW group DW for 3' in SCI was additionally applied. SN60WF IOL was implanted in all eyes. Examinations were performed before and 1, 30, 180 days, one and two years after surgery. Uncorrected and corrected distance visual acuity (UDVA, CDVA), intraocular pressure (IOP), surgically induced astigmatism (K2-SIA), spherical equivalent (SEQ), endothelial cell and the complications were examined. Total PCO score in the area of 1 and 3 mm zone and capsulorhexis (CAPS) were determined using EPCO 2000. One patient was withdrawn from the DW group as he did not report for the examinations.

RESULTS

As far as safety parameters are concerned, no differences were observed between groups in two-year follow-up (p > 0.05). However, in the DW group the endothelial cell loss was higher (p < 0.05). Total PCO score differences were observed in both groups between the areas (p < 0.05). In the CAPS area, both Total PCO score and PCO area were decreased in the DW group (p < 0.05). PCO was also lower within 3 mm zone in the DW group (p < 0.05).

CONCLUSIONS

SCI is a safe procedure and the endothelial cells loss can be associated with the Perfect Capsule™ device (Milvella) in the anterior chamber insertion. DW irrigated for 3' reduces PCO in long-term follow-up.

Development of endothelium-denuded human umbilical veins as living scaffolds for tissue-engineered small-calibre vascular grafts

Tissue-engineered small-calibre vessel grafts may help to alleviate the lack of graft material for coronary and peripheral bypass grafting in an increasing number of patients. This study explored the use of endothelium-denuded human umbilical veins (HUVs) as scaffolds for vascular tissue engineering in a perfusion bioreactor. Vessel diameter (1.2 ± 0.4 mm), wall thickness (0.38 ± 0.09 mm), uniaxial ultimate failure stress (8029 ± 1714 kPa) and burst pressure (48.4 ± 20.2 kPa, range 28.4-83.9 kPa) were determined in native samples. The effects of endothelium removal from HUVs by enzymatic digestion, hypotonic lysis and dehydration were assessed. Dehydration did not significantly affect contractile function, tetrazolium dye reduction, mechanical strength and vessel structure, whereas the other methods failed in at least one of these parameters. Denudation by dehydration retained laminin, fibronectin, collagen and elastic fibres. Denuded HUVs were seeded in a perfusion bioreactor with either allogeneic HUVs endothelial cells or with saphenous vein endothelial cells harvested from patients with coronary artery disease. Seeding in a perfusion bioreactor resulted in a confluent monolayer of endothelial cells from both sources, as judged by histology and scanning electron microscopy. Seeded cells contained von Willebrand factor and CD31. In conclusion, denuded HUVs should be considered an alternative to decellularized blood vessels, as the process keeps the smooth muscle layer intact and functional, retains proteins relevant for biomechanic properties and for cell attachment and provides a suitable scaffold for seeding an autologous and flow-resistant endothelium.

Ablation of lens epithelial cells with a laser photolysis system: histopathology, ultrastructure, and immunochemistry

PURPOSE

To evaluate efficacy of a neodymium:YAG (Nd:YAG) laser photolysis system in removing lens epithelial cells (LECs) and characterize the effect of the laser on laminin and fibronectin involved in LEC adhesion and migration.

METHODS

Cadaver eyes were evaluated using the Miyake technique. The lenses were removed with phacoemulsification. The modified Nd:YAG laser was used to clean the LECs from the capsule. Only the fornix was cleaned in some eyes and the anterior subcapsular area in other eyes. Some areas were not treated and acted as controls. Standard irrigation/aspiration (I/A) removal of LECs was performed in additional eyes. The eyes were analyzed using light microscopy and immunohistochemical staining.

RESULTS

Histopathologic evaluation showed that the laser removed the LECs from the anterior lens capsule and from the fornix. Immunohistochemical staining showed fibronectin and laminin staining in the untreated areas that was absent in the treated areas. Standard I/A removal of the LECs showed absence of cells but persistent laminin and fibronectin. Electron microscopy showed epithelial cells in untreated areas with an absence of the LECs and debris in treated areas.

CONCLUSIONS

The laser photolysis system removed LECs from the anterior lens capsule and capsule fornix. Along with the cells, laminin, fibronectin, and cell debris remained in the untreated areas but were removed by the treatment. This treatment may be useful in preventing posterior capsule opacification.

Long-term results of sealed capsule irrigation using distilled water to prevent posterior capsule opacification: a prospective clinical randomised trial

BACKGROUND

We investigated long-term safety and efficacy of sealed capsule irrigation (SCI) during cataract surgery to prevent posterior capsule opacification (PCO).

METHODS

One eye of each of 17 patients (mean age: 70.1+/-9.7 years) who presented with bilateral cataracts was randomly chosen for SCI treatment. After phacoemulsification, the capsular bag was vacuum sealed with the PerfectCapsule device (Milvella) followed by SCI using distilled water for two minutes. No vacuum loss occurred during irrigation. Each patient's fellow eye served as a control. One hydrophilic acrylic intraocular lens model was implanted in all eyes. Five patients had to be excluded due to deep anterior chamber, small pupil or unilateral surgery. Follow-up examinations took place one day and one, three, six, 12 and 24 months after surgery. We evaluated safety parameters, anterior capsule (AC) overlapping and PCO.

RESULTS

Postoperatively, mean best corrected visual acuity, pachymetry, endothelial cell count, intraocular pressure, AC overlapping and PCO showed no statistically significant difference between SCI and the control group (p>0.05, Wilcoxon test).

CONCLUSION

SCI is a safe procedure and enables the specific pharmacological targeting of lens epithelial cells inside the capsular bag. Using distilled water, however, it is not possible to reduce PCO development significantly. Thus, alternative substances should be evaluated.

After-cataract evaluation after using balanced salt solution, distilled deionized water, and 5-fluorouracil with a sealed-capsule irrigation device in the eyes of 4-week-old rabbits

PURPOSE

To evaluate the Perfect Capsule sealed-capsule irrigation device (Milvella Pty., Ltd.) using 3 substances in young rabbit eyes.

SETTING

St. Erik's Eye Hospital, Stockholm, Sweden.

METHODS

Thirty 4-week-old rabbits had clear lens extraction in both eyes. In 1 randomly selected eye, the Perfect Capsule was applied and the lens capsule was irrigated for 5 minutes with 1 of 3 substances: balanced salt solution (BSS), distilled deionized water (DDW), or 5-fluorouracil (5-FU) 50 mg/mL. In the other eye, no sealed capsule irrigation was used. Forty days postoperatively, the animals were killed and the eyes fixed in formalin for histologic analysis. After-cataract was evaluated in 3 ways: clinically, from photographs, and histologically. Central posterior capsule thickness was evaluated using a microscope, camera, and computer.

RESULTS

The Perfect Capsule sealed-capsule irrigation system could be used in all selected eyes. The vacuum to the anterior capsule was tight, and the system was sealed in all eyes. After-cataract developed in the BSS group and DDW group, but not in the 5-FU group. The 5-FU group had significantly less after-cataract than the other 2 groups (P<.05). There was no difference between the groups in capsule thickness.

CONCLUSIONS

The Perfect Capsule sealed-capsule irrigation system could be used in small eyes. Distilled deionized water did not prevent after-cataract in rabbit eyes with highly proliferative cells, but 5-FU was effective in preventing after-cataract.

Effect of anterior capsule polishing on the posterior capsule opacification–inhibiting properties of a sharp-edged, 3-piece, silicone intraocular lens

PURPOSE

To evaluate the long-term effects of anterior capsule polishing on regeneratory posterior capsule opacification (PCO), anterior capsule opacification (ACO), and fibrotic PCO with a silicone intraocular lens (IOL) with sharp optic edges.

SETTING

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

METHODS

This prospective bilateral randomized patient- and examiner-masked clinical trial comprised 130 eyes of 65 patients with bilateral age-related cataract. All eyes had implantation of a 3-piece silicone IOL with a truncated, sharp-edged optic (CeeOn Edge 911A, Advanced Medical Optics). In 1 eye, the anterior capsule was extensively polished using an aspiration curette after phacoemulsification and cortex aspiration. Regenerative PCO was quantified objectively, while ACO and fibrotic PCO were graded subjectively 1, 2, 3, and 5 years postoperatively.

RESULTS

The mean ACO score was significantly lower in the eyes in which the anterior capsule had been polished (1 year, P<.02; 2 years, P<.03; 3 years, P<.01; 5 years, P<.01). The mean difference in regeneratory PCO and fibrotic PCO scores between the 2 groups was not statistically significant.

CONCLUSIONS

Three years after cataract surgery, eyes in which the anterior capsule had been polished had significantly less ACO. However, polishing did not lower PCO intensity when a sharp-edged CeeOn 911A IOL was implanted in the bag. Although results indicate that anterior capsule polishing may enhance the development of regeneratory PCO, this trend did not reach statistical significance.

Development of an accommodating intra-ocular lens--in vitro prevention of re-growth of pig and rabbit lens capsule epithelial cells

Cataract surgery is routinely performed to replace the clouded lens by a rigid polymeric intra-ocular lens unable to accommodate. By implanting a silicone gel into an intact capsular bag the accommodating properties of the natural lens can be maintained or enhanced. The implantation success of accommodating lenses is hampered by the occurrence of capsular opacification (PCO) due to lens epithelial cell (LEC) growth. In order to prevent LEC proliferation, a treatment regime using actinomycin D, cycloheximide and water was developed. The effectiveness of treatment was analyzed using an in vitro, MTT-based cell culture system and an ex vivo pig eye model in which the implanted lens-in-the-bag is cultured as a whole. LEC were exposed to treatment solutions for 5 min, then the cells were allowed to recover and to re-colonize the substratum. MTT conversion by cells was transiently inhibited by cycloheximide dissolved in water and by water alone. Exposure to actinomycin D resulted in a lasting inhibition of MTT conversion and consequently cell proliferation. These in vitro data could not be fully reproduced in the ex vivo pig eye model due to essential differences between both models. Treatment with actinomycin D containing solutions, however, resulted in a nearly complete absence of cells on the capsular wall. The pig eye model is a promising approach to further evaluate the effects of peri-surgical treatment during the accommodating intra-ocular lens implantation.

New techniques and technologies for pediatric cataract surgery

PURPOSE OF REVIEW

This paper surveys the literature from April 2004 to April 2005 and addresses trends in pediatric cataract surgery techniques.

RECENT FINDINGS

The evolution of pediatric cataract surgery continues, with many adult cataract surgical techniques being applied to children with minor technical adjustments. More and more, surgeons are implanting intraocular lenses in younger children. One of the most widely reported technologic advances in 2004-2005 was the use of hydrophobic acrylic intraocular lenses in children. Predicting axial growth, and refractive change that accompanies it, is one of the major remaining challenges for the long-term care of children who have had cataract surgery.

SUMMARY

Automation and intraocular lenses have helped to provide better anatomic and functional outcome for cataract surgery in children. Two major challenges in the coming years will be to find a way to obviate invasive procedures like posterior capsulotomy and vitrectomy and to study the growth of eyes in a well designed prospective study that will help to design new intraocular lens power calculation formulas specifically suited for children's eyes.

[New methods for the prevention of posterior capsule opacification]

Even though tremendous advances have been made especially during the last 10-15 years in terms of surgical techniques and improvement of implant technology, posterior capsule opacification (PCO) still remains a serious long-term complication. New clinical and laboratory studies (especially of autopsy eyes) have improved our understanding of how IOL design and material influence PCO. Sharp edge optic designs of IOLs of various materials have been shown to significantly reduce secondary cataract. The application of pharmacological substances selectively into the capsular bag is now possible due to the development of the PerfectCapsule System for vacuum-sealed capsule irrigation. Major advances in other areas of biotechnology and immunology including gene therapeutic methods offer totally new approaches for the future in the elimination of lens epithelium cells from the capsular bag. This survey gives an update on current and future means and trends to reduce or prevent PCO formation.

New phacoemulsification technology

PURPOSE OF REVIEW

Familiarization with each of the manufacturers' latest machines and upgrades assists in understanding the advances made in phacoemulsification technology.

RECENT FINDINGS

Improvements in the delivery of energy through power modulations, alternative and adjunctive energy sources, and advanced fluidics allow the safe use of bimanual microincision techniques for lens extraction.

SUMMARY

Continual advances in phacoemulsification technology and adjunctive surgical devices allow cataract surgery to be performed more safely and efficiently.