Lamellar keratoplasty with a novel anterior chamber system and organ cultured donor corneas.

PURPOSE: To present a novel artificial anterior chamber system for anterior and posterior lamellar keratoplasty. METHODS: The artificial anterior chamber system MOZARTTM in conjunction with the AMADEUSTM II microkeratome was evaluated for its applicability in anterior and posterior lamellar keratoplasty using organ cultured donor corneas. RESULTS: Twelve patients underwent microkeratome-assisted lamellar keratoplasty for corneal opacifications due to either anterior stromal scaring or endothelial decompensation. Eight patients underwent Descemet stripping automated endothelial keratoplasty (DSAEK) and 4 patients underwent anterior lamellar keratoplasty (ALK). A 400-microm and 250-microm cutting head was used for DSAEK and ALK, respectively. In all patients, an 8.5-mm suction ring was applied. For the 250-microm cutting head, a mean anterior lamella thickness of 244+/-12 microm was found. For the 400-microm cutting head, a mean anterior lamella thickness of 390+/-18 microm was found. The graft diameter was 8.85+/-0.5 mm for the 8.5-mm suction ring with both cutting heads. Deswelling of the anterior donor lamella was 11.5% compared to 30% of the posterior lamella transplant after 6 months of follow-up. CONCLUSION: The AMADEUSTM II microkeratome in conjunction with the MOZARTTM artificial anterior chamber system proved to be a suitable device for modern lamellar keratoplasty. Swelling and deswelling characteristics of organ cultured corneas need to be further investigated to optimize the deswelling time prior to donor cornea sectioning in lamellar keratoplasty.

Amadeus II microkeratome: optimizing microkeratome settings for high flap accuracy using optical low coherence reflectometry.

PURPOSE: To investigate the impact of various experimental microkeratome settings and blade reuse on the accuracy of the flap thickness created with the new Amadeus II microkeratome (SIS, Ziemer Ophthalmic, Port, Switzerland). METHODS: In this prospective study, 120 porcine eyes were used to create corneal flaps with the Amadeus II using 2 different cutting heads (140 microm, 160 microm) with the Surepass blade. Using each blade twice, a head advance speed of 1.5 mm/s and 3.5 mm/s and oscillation rates of 8000 rpm, 10,000 rpm, and 13,000 rpm were used. Flap thickness was measured by optical low coherence reflectometry (OLCR). Descriptive statistical analysis was based on means, medians, and quartiles, with graphical representation on box plot. Pearson correlation test and Mann-Whitney U-test for unpaired samples were employed to identify the impact of different settings. RESULTS: Using the 140 microm cutting head, highest precision of the flap thickness was achieved with a head advance rate of 1.5 mm/s and an oscillation rate of 10,000 rpm (mean 132.1+/-10.0 microm; range 120.2-147.2 microm). Reusing the blade, highest accuracy (mean 130+/-6.9 microm; range 118.5-135 microm) was achieved with 8000 rpm. Using the 160 microm cutting head, an optimum flap thickness was reached with a head advance rate of 3.5 mm/s and an oscillation rate of 13,000 rpm (mean 162.4+/-7.7 microm; range 151.9-169.8 microm). Reusing the blade with the 160 microm cutting head, an adjustment to 3.5 mm/s and 10,000 rpm was necessary (mean 157.4+/-7.7 microm; range 153.7-161.8 microm). CONCLUSIONS: Optimized microkeratome settings lead to minimized deviation from the intended flap thickness and are mandatory to improve flap accuracy. OLCR is an ideal method to proof individualized settings.

Customizing the Amadeus II microkeratome: evaluation of cut quality with various settings using electron microscopy.

PURPOSE: To evaluate the cut quality of keratectomy specimens created with the new Amadeus II microkeratome (SIS, Ziemer Ophthalmic, Port, Switzerland) using scanning electron microscopy (SEM). Methods. Corneal cuts were performed in 24 freshly enucleated porcine eyes using the Amadeus II microkeratome with combinations of cutting-head depth, oscillation rate, head-advance speed, and reuse of the blade. For the cutting trials, a 140-microm and 160-microm cutting head with three oscillation rates of 8,000, 10,000, and 13,000 rpm and two head-advance speed rates of 1.5 and 3.5 mm/s were chosen. In each setting, the blade was reused for a second time. All eyes were included, resulting in 4 groups with 6 eyes for each configuration. The surface and edge of the corneal cut was examined using SEM. RESULTS: At fixed oscillation rates, an increase in head-advance speed led to lower quality cuts, higher surface roughness, and irregular cut edges for both cutting heads (140 microm/160 microm), especially when using the blade for a second time. At fixed head-advance speeds an increase in oscillation rates improved the cut quality for both cutting heads (140 microm/160 microm). This results in smoother surface characteristics and more regular cut edges, especially when using the blade for the first time. CONCLUSIONS: Using the Amadeus II microkeratome for laser in situ keratomileusis procedures, the optimum oscillation rate, the optimum head-advance speed, and a single use of the blade will produce a very smooth and regular surface and cut edge for safe, comfortable, and improved customized refractive surgery.

Performance of the Acri. Smart 46S intraocular lens in pediatric microincision cataract surgery.

PURPOSE: To evaluate the performance of the microincision Acri. Smart 46S intraocular lens (IOL) (Acri.Tec) in pediatric cataract surgery. SETTING: Department of Ophthalmology, Ludwig-Maximilians University, Munich, Germany. METHODS: Thirty-two consecutive eyes of 22 children who had cataract surgery with planned IOL implantation were retrospectively analyzed. Intraoperative and postoperative IOL performance, posterior capsule opacification (PCO) formation, best corrected far and near visual acuities, and astigmatism were analyzed. The minimum follow-up was 12 months. RESULTS: The median patient age was 4.5 years (range 2 to 13 years) and the median follow-up, 21 months (range 12 to 29 months). In 94% of eyes, the IOL was implanted in the capsular bag; in 6%, it was placed in the ciliary sulcus. A primary posterior capsule opening was created in 12.5% of eyes. The posterior capsule was intact at the end of surgery in 81% of eyes. Capsule rupture occurred during lens aspiration in 3% of eyes, and a primary capsular defect was present in a patient with traumatic cataract. Posterior capsule opacification that required a second intervention during the follow-up period developed in 35% of eyes. All IOLs were well centered and had a clear optical axis at the end of follow-up. CONCLUSIONS: The Acri. Smart (46S) IOL was found to be suitable for pediatric bimanual microincision cataract surgery. The feasibility of inserting the IOL through of the sub-2.0 mm paracentesis minimizes manipulation of the juvenile eye.

Pulsed electron avalanche knife: new technology for cataract surgery.

BACKGROUND: The pulsed electron avalanche knife (PEAK-fc) is a new pulsed electrosurgical device that allows for precise, "cold" and traction-free tissue dissection. AIM: To evaluate the surgical applicability, safety and potential complications of PEAK-fc in complicated cataract surgery. METHODS: The study included five children with congenital cataracts, two patients with advanced senile cataracts, six adults with mature cataracts, three of them with posterior iris synechia, three patients with post-traumatic cataracts with zonulolysis, one patient with intumescent traumatic cataract and three patients with massive anterior capsule opacification. Anterior and posterior capsulotomies, iris synechiolysis, dissection of anterior capsule opacification and fibrotic scar tissue were performed. PEAK-fc was set at voltages of 500-700 V, pulse duration of 0.1 m and repetition rate of 40-100 Hz. RESULTS: Anterior and posterior capsulotomies were successfully and safely performed in all eyes. The edges of capsulotomies appeared sharp, showing only limited collateral damage. PEAK-fc worked best by just gently touching the capsule, thereby avoiding tractional forces or pressure on the lens capsule. Posterior iris synechiae could be released and anterior capsule opacification was dissected without complications. CONCLUSIONS: PEAK-fc is a very helpful cutting device for complicated cases of cataract surgery, especially for mature and congenital cataracts, traumatic zonulolysis or anterior segment complications after intraocular inflammation.

Pulsed electron avalanche knife for capsulotomy in congenital and mature cataract.

The pulsed electron avalanche knife (PEAK-fc, Carl Zeiss Meditec) is an electrosurgical cutting device that allows precise "cold" and traction-free tissue dissection. We describe its applicability and safety for anterior capsulotomy in a child with congenital cataract and an adult patient with mature cataract. The PEAK-fc was set at a voltage of 600 V and a pulse repetition rate of 80 Hz. Anterior capsulotomies were successfully and safely performed in both cases, with the edges of capsulotomies appearing sharp and showing only limited collateral damage. The PEAK-fc appears to be a helpful cutting device for complicated cases of cataract surgery, especially for mature and congenital cataracts.

The role of NGF signaling in human limbal epithelium expanded by amniotic membrane culture.

PURPOSE: Amniotic membrane (AM) transplantation facilitates rapid epithelialization in severe neurotrophic corneal ulcers. To elucidate its action mechanism, we investigated the expression of ligands and receptors of the neurotrophin family by human limbal epithelial (HLE) cells expanded on AM cultures. METHODS: Expression of nerve growth factor (NGF); neurotrophins (NT)3 and NT4; brain-derived neurotrophic factor (BDNF); tyrosine kinase-transducing receptors TrkA, TrkB, and TrkC; and a pan-NT low-affinity receptor (p75(NTR)) was examined by immunostaining in the normal human corneolimbus, HLE grown on intact epithelially denuded AM, and stratified HLE, after subcutaneous implantation in NIH-bg-nu-xid BR mice. NGF protein level was assayed by an ELISA in extracts of intact and epithelially denuded AM. K252a, a specific inhibitor of TrkA autophosphorylation, was added to test whether it would inhibit HLE expansion on AM culture. RESULTS: Strong positive TrkA staining was confined to the basal epithelial cell layer of normal corneal and limbal epithelia, with the highest intensity noted in the limbus. TrkA staining was also strongly positive in the basal layer of HLE cells cultured on intact and epithelially denuded AM and in basal and some suprabasal layers of stratified HLE transplanted in nude mice. Positive staining of p75(NTR) was noted in the full-thickness of the corneal epithelium but was limited to the superficial layers of the limbus and in HLE cells cultured on intact and epithelially denuded AM, but was weak in HLE transplanted to nude mice. Weak staining of NT3 and TrkC was noted in the suprabasal layers of corneal and limbal epithelia but was negative in the stratified HLE in nude mice. Negative staining of NGF, NT4, BDNF, and TrkB was noted in all specimens tested. The NGF protein level was readily measured as 35.6 +/- 9.1 and 41 +/- 12.5 pg/mg protein in the homogenate of the intact and epithelially denuded AM, respectively (P = 0.0256). K252a significantly inhibited the HLE outgrowth on intact AM culture (P = 0.024). CONCLUSIONS: The strong expression of TrkA but not p75(NTR) in the limbal basal epithelial cells in vivo suggests that NGF signaling favors limbal epithelial stem cell survival. Such a phenotype is preserved in HLE cells on AM. Blocking NGF signaling significantly retarded HLE expansion on AM, supporting the notion that NGF is important in expansion of limbal epithelial progenitor cells. Furthermore, a high and therapeutic level of NGF was present in AM. Collectively, these findings indicate that denervated neurotrophic ulcers are associated with poor epithelial stem cell function at the limbus. Future studies are needed to determine whether AM transplantation to heal such ulcers may include the promotion of nerve regeneration and survival of epithelial progenitor cells.

Connexin 43 expression and proliferation of human limbal epithelium on intact and denuded amniotic membrane.

PURPOSE: Stem cell (SC)-containing limbal basal epithelium and transient amplifying cell (TAC)-containing corneal basal epithelium lie on different mesenchymal matrices. The gap junction protein connexin 43 (Cx43) is absent in the limbal basal epithelium but is present in the corneal basal epithelium, suggesting that the expression of Cx43 denotes SC differentiation into TACs. Amniotic membrane (AM) can expand limbal epithelial progenitor cells in vivo and in culture for subsequent corneal surface reconstruction. In this study, the modulation of Cx43 expression, gap junction intercellular communication (GJIC), and proliferative activity of ex vivo expanded human limbal epithelial (HLE) cells on intact and epithelially denuded AM was investigated. METHODS: HLE cells were expanded on intact (i.e., remaining devitalized amniotic epithelium) or epithelially denuded AM (EDTA-treated). Cx43 expression and 24-hour 5-bromo-2'-deoxyuridine-5'monophosphate (BrdU) labeling index (percentage) were determined by double immunostaining. GJIC was investigated by a scrape-loading dye transfer assay. In a subset of cultures Cx43 and K3 keratin as well as BrdU-retaining nuclei were analyzed in the stratified epithelium obtained 5 days after subcutaneous transplantation in NIH bg-nu-xidBR mice of AM cultures continuously labeled with BrdU for 7 days. RESULTS: The outgrowth rate, overall, was significantly higher on EDTA-treated AM than on intact AM (P < 0.05). Cx43 was expressed in 12.4% +/- 14.5% (n = 5) on intact and 57.5% +/- 18.2% (n = 5) on EDTA-treated AM (P < 0.05). The BrdU labeling index was 2.4% +/- 0.9% (n = 5) for the intact AM group, which was significantly less than 22.5% +/- 8.2% (n = 5) for EDTA-treated AM (P < 0.05). BrdU-labeled cells did not express Cx43. The dye transfer assay revealed reduced GJIC on both AM-cultured groups compared with the control culture on plastic (P < 0.002). GJIC on intact AM (17%) was reduced compared with that on EDTA-treated AM (27%; P = 0.42). After xenotransplantation, the basal layer of the stratified epithelium was Cx43 and K3 keratin negative and retained BrdU on intact AM, resembling characteristics of the limbal basal epithelium in vivo. In contrast, that of EDTA-treated AM was Cx43 and K3 keratin positive without BrdU retention, resembling characteristics of the corneal epithelium in vivo. CONCLUSION: These data indicate that denudation of the devitalized amniotic epithelium to expose its basement membrane might be a microenvironmental cue to promote TAC differentiation. The model system described herein is ideal for future exploration of the exact mechanistic operation in the microenvironmental niche that maintains the "stemness" of limbal SCs as well as in the signal that promotes corneal TAC differentiation.

Modulation of keratin and connexin expression in limbal epithelium expanded on denuded amniotic membrane with and without a 3T3 fibroblast feeder layer.

PURPOSE: Based on the knowledge that limbal epithelial stem cells (SCs) do not express keratin-3 (K3), connexin (Cx)43, and Cx50, a study was conducted to investigate amniotic membrane (AM) culturing conditions that promote limbal SC expansion. METHODS: Human limbal epithelium was expanded on intact and epithelially denuded AM, with or without a 3T3 feeder layer, and subsequently transplanted to nude mice to induce epithelial stratification and differentiation. Immunostaining and Western blot analysis were used to determine protein expression of K3, Cx43, and Cx50. Expression of integrin-alpha3, -beta1, -alpha6, and -beta4 was investigated by immunostaining. RESULTS: Protein levels of K3, Cx43, and Cx50 in limbal epithelium on intact AM was lower than those on denuded AM. Addition of 3T3 to denuded AM increased the level of Cx43 but decreased that of Cx50. After xenotransplantation, the basal layer of the resultant stratified epithelium on intact AM did not express K3, Cx43, and Cx50, whereas that on denuded AM expressed all three markers. The addition of 3T3 resulted in positive staining of Cx43 and K3 but negative staining of Cx50 in the basal epithelium. After stratification, integrin expression was detected at the basal epithelium-amniotic basement membrane interface in all three culture conditions. CONCLUSIONS: Limbal cultures on intact AM retain a limbal epithelial phenotype, whereas those on denuded AM differentiate into a corneal phenotype. The addition of 3T3 slows but does not prevent corneal differentiation on denuded AM. Such a difference may involve integrin-mediated extracellular matrix interactions.

Overexpression of Insulin-like growth factor-binding protein-2 in pterygium body fibroblasts.

PURPOSE: To examine the expression pattern of insulin-like growth factor-binding protein (IGFBP)-2 in cultured primary pterygium fibroblasts and compare it with expression in normal conjunctival fibroblasts. METHODS: Profile of gene expression by normal conjunctival and primary pterygium fibroblasts was performed by using a cDNA microarray. The overexpression of IGFBP-2 thus identified was further confirmed by RT-PCR and Western blot analysis of cultured cells and by immunohistochemistry on primary pterygium and normal conjunctival tissue sections. RESULTS: A dramatically increased expression of IGFBP-2 mRNA was demonstrated in cDNA microarray membranes from two different pterygium fibroblasts. This finding was confirmed by RT-PCR in four additional different pterygium fibroblasts and by Western blot analysis of their culture supernatants. Immunohistochemistry of frozen sections from primary pterygium demonstrated increased staining in extracellular matrix of the stroma, compared with that of the normal conjunctiva. IGFBP-2 was also found in goblet cells of both normal conjunctival and pterygium epithelia. CONCLUSIONS: The increased expression of IGFBP-2 mRNA and protein in pterygium fibroblasts is further strong evidence to support the transformed phenotype of these cells and helps explain why there is increased growth of fibrovascular tissue. This phenotype may be used as a marker to assess the malignant nature of pterygium growth and recurrence.

Human limbal progenitor cells expanded on intact amniotic membrane ex vivo.

BACKGROUND: The transplantation of human limbal epithelium on amniotic membrane as a substrate is a new treatment for limbal stem cell deficiency. Limbal epithelial stem cells are characterized by a slow cell cycle and the lack of K3 keratin and connexin 43 (Cx43), a gap junction protein. We investigated Cx43 expression, gap junction intercellular communication (GJIC), and proliferative activity of limbal epithelium expanded on amniotic membrane. METHODS: Connexin 43 expression and bromodeoxyuridine (BrdU) incorporation were determined by immunohistology. The GJIC was investigated by a scrape-loading dye transfer assay. Expression of Cx43 and K3 keratin as well as BrdU-retaining nuclei were also analyzed after xenotransplantation in nude mice. RESULTS: Limbal epithelium showed mean +/- SD 12.4% +/- 14.5% positive units of Cx43 expression and a low BrdU labeling index of 2.4% +/- 0.9% (n = 5), of which the latter was due to slow cycling, as proved by its increase to 62.0% +/- 9.5% after continuous BrdU labeling for 5 days. Most of the expanded epithelium did not show GJIC (83%), significantly more than that grown on plastic (6%; P<.002). Basal cells of the stratified epithelium after xenotransplantation did not express Cx43 and K3 keratin, but their nuclei retained BrdU. CONCLUSION: These results support the hypothesis that intact amniotic membrane preferentially preserves and expands Cx43-negative, keratin K3-negative, and GJIC-deficient limbal epithelium, a phenotype resembling that of stem cell-containing limbal basal epithelial cells in vivo. CLINICAL RELEVANCE: Intact amniotic membrane is a suitable substrate for bioengineering limbal epithelia for ocular surface reconstruction.

Ex vivo expansion of limbal epithelial stem cells: amniotic membrane serving as a stem cell niche.

Identification, maintenance, and expansion of stem cells for subsequent transplantation has become a new strategy for treating many diseases in most medical subspecialties. The stem cells of the corneal epithelium are located in the limbal basal layer and are the ultimate source for constant corneal epithelial renewal. Like those in other tissues, limbal stem cells are supported by a unique stromal microenvironment called the stem cell niche, which consists of certain extracellular matrix components, cell membrane-associated molecules, and cytokine dialogues. Destructive loss of limbal stem cells or dysfunction of their stromal environment renders many corneas with a clinical entity called limbal stem cell deficiency, which is characterized by variable extents of conjunctival ingrowth depending on the severity of limbal damage. A new strategy of treating limbal stem cell deficiency is to transplant a bio-engineered graft by expanding limbal epithelial stem cells ex vivo on amniotic membrane. This review summarizes the published literature data collectively explaining how amniotic membrane is an ideal biological substrate that can help maintain and support the expansion of limbal epithelial stem cells.

Amniotic membrane transplantation for bullous keratopathy in eyes with poor visual potential.

PURPOSE: To evaluate the long-term outcomes of epithelial debridement and amniotic membrane transplantation (AMT) for pain and discomfort relief in patients with symptomatic bullous keratopathy and poor visual potential. SETTING: Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA. METHODS: This retrospective study included 18 eyes (18 patients) with bullous keratopathy presenting with intractable pain or discomfort and poor visual potential. After epithelial debridement, all eyes had AMT with the basement membrane side up. During a mean follow-up of 25.1 months +/- 9.6 (SD) (range 12 to 45 months), pain relief, epithelial healing, and visual changes were analyzed. RESULTS: Pain relief was obtained in 88% of patients. Sixty-six percent of eyes had complete resolution of ocular discomfort starting soon after the first postoperative day. One eye had evisceration for persistent pain 10 months postoperatively. Corneal epithelial healing was complete in all except 1 eye. Remaining complaints included foreign-body sensation (5%), tearing (11%), and photophobia (5%). CONCLUSIONS: Amniotic membrane transplantation was a safe, effective, and long-lasting treatment modality for intractable pain associated with chronic bullous keratopathy in eyes with poor visual potential. It can be an alternative to conjunctival flaps for the long-term management of patients with bullous keratopathy in whom corneal transplantation is not indicated. A comparison of the efficacy of AMT with that of other surgical procedures must be performed.

Cleavage of corneal basement membrane components by ethanol exposure in laser-assisted subepithelial keratectomy.

PURPOSE: To determine the anatomic cleavage plane after exposure to 20% ethanol for approximately 20 to 25 seconds to create an epithelial flap in laser-assisted subepithelial keratectomy (LASEK). SETTING: Ocular Surface Research & Education Foundation, Miami, Florida, and Hermann Eye Center Refractive Surgery Center, Houston, Texas, USA. METHODS: Immunofluorescence staining using monoclonal antibodies against laminin 5, collagen VII, and integrins beta(1) and beta(4) was performed to determine the anatomic location of the cleavage plane in an epithelial flap created by 20-second exposure to 20% ethanol in cadaver eyes and in epithelial flaps obtained from LASEK patients. RESULTS: Immunofluorescence staining to laminin 5 and integrin beta(4) was patchy in the lifted flap and the remaining corneal basement membrane. Immunostaining to collagen VII, the main component of anchoring fibrils, remained exclusively in the corneal bed. Immunostaining to integrin beta(1), present in the pericellular location of all epithelial cell layers, remained exclusively in the epithelial flap. This finding was consistent in cadaver corneas and LASEK epithelial flaps. CONCLUSIONS: The cleavage plane of the ethanol-induced corneal epithelial flap is located between the lamina lucida and the lamina densa of the basement membrane, where integrin beta(4) interacts with laminin 5 to form hemidesmosomes.

Corneal cell response after flap creation using a mechanical microkeratome or a 200 kHz femtosecond laser.

PURPOSE: To compare the inflammatory cell response within the corneal flap interface created by a mechanical microkeratome and a femtosecond laser. SETTING: Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany. DESIGN: Experimental in vitro study. METHODS: Corneoscleral buttons of 12 enucleated human eyes not suitable for transplantation were put into organ culture. Corneal flaps were created using a 200 kHz femtosecond laser (Visumax) (femtosecond group) or a mechanical microkeratome (Amadeus) (microkeratome group). Flaps were not lifted after treatment. In 2 corneas, no treatment was performed (control group). Corneas were kept in organ culture for 12 hours thereafter. To evaluate cell-mediated immune reaction, immunofluorescent staining for leucocytes (cluster of differentiation 45) and specifically for dendritic cells (human leukocyte antigen-DR) was performed in every group. A terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to determine apoptosis reaction. RESULTS: The ratio of dendritic cells in the femtosecond group compared with the microkeratome group was 1.2 (P=.02), the ratio of leucocytes was 1.4 (P=.06), and the ratio of apoptotic cells was 1.0 (P=.59). There was no marked significant difference in the distribution of inflammatory cell reaction. The control group showed neither specific inflammatory reaction nor apoptosis. CONCLUSION: This in vitro series of human corneas showed similar inflammatory tissue reaction after femtosecond laser-assisted and microkeratome-assisted flap creation (P<.05). FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Evaluation of interface quality in organ-cultured lamellar corneal transplants.

BACKGROUND: With increasing numbers of lamellar keratoplasties, eye banks are challenged to deliver precut lamellar donor tissue. In Europe, the most common technique of corneal storage is organ culture which requires a deswelling process before surgical processing. The aim of this study was to investigate the influence of different deswelling times on the cutting plane quality after microkeratome-assisted lamellar dissection. METHODS: Eight paired donor corneas (16 specimens) not suitable for transplantation were organ cultured under standard conditions at the Eye Bank of the Ludwig-Maximilians Universität, Munich, Germany. Pairs of corneal buttons were analyzed during the deswelling process in dextrane-containing medium. While one cornea was cut at an early time point during the deswelling process and put back into deswelling medium thereafter, the partner cornea was completely deswollen and dissected after 72 hours. Specimens were then further processed for scanning electron microscopy. Surface quality was assessed both digitally using Scanning Probe Imaging Processing software, and manually by three blinded graders. RESULTS: The corneal buttons processed at the beginning of the deswelling process had a smoother surface when compared to the partner cornea that was cut at the end of the deswelling process. In our setting, no relevant difference was detectable between manual and automated microkeratome dissection. CONCLUSION: For lamellar keratoplasty, organ-cultured corneas should be processed at an early stage during the deswelling process. We interpret the smoother dissection plane during early deswelling as a result of mechanical properties in a highly hydrated cornea.

Application of 10% povidone iodine reduces conjunctival bacterial contamination rate in patients undergoing cataract surgery.

PURPOSE: To determine the efficacy of 10% povidone iodine (PVI) drops given before cataract extraction in addition to routine irrigation of the conjunctival sac with 1% PVI. METHODS: This prospective, randomized, single-center study at the Department of Ophthalmology, Ludwig-Maximilians-University, Munich, includes 263 eyes of 242 patients undergoing cataract surgery. Patients were randomized to receive 3 drops of 10% PVI into the conjunctival sac (study group) or no PVI drops (control group). All patients underwent periorbital disinfection with 10% PVI followed by irrigation of the conjunctiva with 10 mL of 1% PVI. Specimens were obtained prior to the application of PVI, after antibiotic administration (T1), after irrigation with PVI but before surgery (T2), and at the conclusion of surgery (T3). RESULTS: After PVI disinfection, the number of positive cultures was significantly reduced in all groups (p<0.0001) from 69%-93% at T1 to 1%-16% at T3. In outpatients, the study group showed significantly fewer positive cultures at the conclusion of surgery compared to the control group (4% vs 16%; p=0.03). Also in inpatients significant fewer positive cultures were found in the study group compared to the control group at T2 (12% vs 28%; p=0.03) and at T3 (1% vs 10%; p=0.03). CONCLUSIONS: Three additional drops of 10% PVI prior to surgery provided additional benefit by reducing the conjunctival bacterial contamination rate even in the setting of preoperative irrigation of the conjunctiva with 1% PVI.

Real-time intraocular pressure measurement in standard and microcoaxial phacoemulsification.

PURPOSE: To evaluate intraocular pressure (IOP) in the vitreous cavity during various stages of cataract surgery. SETTING: University Eye Hospital, Ludwig-Maximilians University, Munich, Germany. METHODS: In consecutive eyes having combined phacoemulsification, intraocular lens implantation, and pars plana vitrectomy, IOP was monitored in real time through a 25-gauge pars plana cannula connected to an external pressure transducer. Surgery was performed by standard clear corneal phacoemulsification with a 2.5 mm incision and a Mega-Tip (1.26 mm aperture) (Group 1) or by microcoaxial phacoemulsification with a CMP-Tip (0.80 mm aperture) (Group 2). RESULTS: The 2 groups had 5 eyes each. The mean IOP in Group 1 and in Group 2, respectively, was 15.9 mm Hg +/- 9.5 (SD) and 17.0 +/- 13.5 mm Hg preoperatively (P = .442), 40.1 +/- 12.7 mm Hg and 36.5 +/- 17.2 mm Hg during lens removal (P<.001), 17.6 +/- 14.2 mm Hg and 22.6 +/- 8.6 mm Hg during irrigation/aspiration (P<.001), 13.3 +/- 13.2 mm Hg and 16.3 +/- 13.1 mm Hg during IOL implantation (P = .005), and 22.9 +/- 7.0 mm Hg and 21.5 +/- 10.0 mm Hg after IOL implantation through the end of surgery (P = .329). CONCLUSIONS: Although the IOP levels were significantly lower than those in previous studies, both phacoemulsification techniques had safe IOP profiles during various steps of surgery. Real-time IOP monitoring may prevent the surgeon from inducing excessive IOP elevation during intraocular manipulation. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Propionibacterium acnes in capsular bag distension syndrome.

We report a case of capsular bag distension syndrome that developed 6 years after uneventful phacoemulsification with implantation of a foldable, single-piece acrylic intraocular lens (IOL) (AcrySof MA60BM). Slitlamp microscopy revealed a deep anterior chamber with no flare or cells. The posterior capsular bag was distended by a homogeneous milky substance between the back of the IOL and the capsular bag. Using a pars plana approach, a 23-gauge bimanual capsulotomy and anterior vitrectomy were performed. Microbiological analysis revealed Propionibacterium acnes in the material inside the capsular bag. The postoperative period was uneventful. Four weeks after surgery, visual acuity was restored and there were no signs of intraocular inflammation. The origin of late capsular bag distension is not fully understood; it may involve an infectious component with propionibacteria. A surgical approach and removal of the potentially infectious material can be considered as an alternative to neodymium:YAG capsulotomy.

Posterior lamellar disc dislocation into the vitreous cavity during descemet stripping automated endothelial keratoplasty.

We present a case of a dislocated posterior lamellar lenticule into the vitreous cavity during Descemet stripping automated endothelial keratoplasty. After insertion of the donor disc in a partially vitrectomized eye with partial iris loss, the graft dislocated into the vitreous cavity. With a standard 3-port vitrectomy and the help of perflourocarbon fluid, the graft was lifted into the anterior segment of the eye and firmly attached to the recipient cornea using liquid-air exchange. The postoperative follow-up was without complications. The cornea was clear at the third day after surgery without recurrent graft dislocation.