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.

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.

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.

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.

Optimizing the deswelling process of organ-cultured corneas.

PURPOSE: During deswelling of organ-cultured human corneas, endothelial cell loss occurs. Therefore, it is necessary to minimize the deswelling time and achieving an optimal central corneal thickness (CCT) of approximately 550 microm at the same time. We investigated the minimal deswelling time necessary and analyzed endothelial cell loss. METHODS: Fifty-eight human corneas were stored between 13 and 81 days in organ culture. CCT was measured by optical coherence tomography. Measurements were performed before preparation, during culturing, before deswelling, and after varying deswelling periods (1-72 hours) using 5% dextran. Additionally, vital staining was performed in 6 human corneas to assess endothelial cell loss between 24 and 30 hours of deswelling. To evaluate absolute cell loss, endothelial cells were counted on human corneal pairs after 24 and 30 hours of deswelling. RESULTS: After organ culture, mean CCT was 1194 microm. After 24 hours of deswelling in dextran-containing medium, mean CCT was 600 microm, whereas after 30 hours, mean CCT was 510 microm and hardly any corneas showed a CCT of more than 550 microm. Almost no further decrease in CCT was observed thereafter. No factors could be identified predicting the necessary deswelling time; however, paired corneas showed significant correlation of deswelling characteristics. We did not see any differences in endothelial cell loss 24 and 30 hours of deswelling or the ratio of living to dead endothelial cell counts. CONCLUSIONS: Deswelling for 24 hours does not provide an optimal corneal thickness. Because endothelial cell loss does not increase between 24 and 30 hours of deswelling, a period of 30 hours is more suitable for obtaining sufficient corneal thickness.

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.

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.

The challenge of dry eye diagnosis.

The currently available methods for the diagnosis of dry eye are still far from being perfect for a variety of reasons. This review attempts to highlight the advantages and disadvantages of both traditional tests (such as Schirmer's test, break-up time and ocular surface staining) and innovative noninvasive procedures, including tear meniscus height measurement, corneal topography, functional visual acuity, tear interferometry, tear evaporimetry and tear osmolarity assessment.

Eccentric lamellar keratolimbal grafts harvested with a manually guided microkeratome. Technical report.

BACKGROUND: To perform lamellar keratolimbal allograft transplantation in a one-step procedure with a single graft, we investigated the feasibility of harvesting eccentric lamellar keratolimbal grafts from conventionally processed corneoscleral buttons using a manually guided microkeratome in conjunction with an artificial anterior chamber system. METHODS: We used the Moria LSK-One microkeratome and the automated lamellar therapeutic keratoplasty (ALTK) system (Antony, France). Ten human donor eyes were used to obtain single-piece lamellar keratolimbal grafts. Specimens were processed for light and electron microscopy. RESULTS: Eccentric keratolimbal grafts could be obtained from all human donor buttons. Grafts include a crescent-shaped limbal and a large corneal portion. No visible damage to the limbal region was discernible. CONCLUSION: Our data show that the LSK-One microkeratome in conjunction with the ALTK system allows harvesting eccentric keratolimbal grafts from donor corneoscleral buttons.

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.

Persistent serous retinal detachment after radial optic neurotomy.

We report the case of a patient presenting with serous retinal detachment following radial optic neurotomy for central retinal vein occlusion. Initially, the retinal detachment was successfully treated by a second vitrectomy and laser coagulation. After reabsorption of the gas tamponade, a recurrence of the retinal detachment was seen with no detectable retinal break. Although other mechanisms should be taken into account, this case indicates that it is possible to create a fistula between the subarachnoid and subretinal space. We conclude from this observation that special attention should be paid to the depth of the radial incision into the optic nerve head.

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.

Pulsed electron avalanche knife in vitreoretinal surgery.

PURPOSE: To evaluate the advantages, disadvantages, safety, and surgical applicability of the pulsed electron avalanche knife (PEAK-fc), a new electrosurgical knife for "cold" and tractionless cutting, in vitreoretinal surgery. PEAK-fc is equipped with an integrated fiberoptic that makes bimanual procedures in intraocular surgery possible. METHODS: A prospective consecutive trial of 18 eyes in 18 patients who underwent vitreoretinal surgery for proliferative diabetic retinopathy, proliferative vitreoretinopathy, subretinal macular hemorrhage, or macular pucker was performed. The following specific maneuvers were performed with PEAK-fc: transection of epiretinal membranes, retinotomies, retinal vessel coagulation, and posterior membranectomy. RESULTS: Detached and attached retina could be dissected successfully in eight cases. Intraoperatively, incision edges were sharply demarcated, showing no visible collateral damage. Deeper layers than the neurosensory retina were not affected. With the bimanual approach, epiretinal avascular and vascular membranes could be removed in 10 cases. Hemorrhages occurring during transection of vascularized membranes could be stopped immediately using the coagulation mode of PEAK-fc. Posterior capsule fibrosis was successfully excised in one patient. No complications were observed. CONCLUSION: PEAK-fc offers precise and tractionless tissue cutting during ocular surgery. Using different waveform parameters, the same device performs cold cutting and/or "hot" coagulation, thus improving the precision, safety, and ergonomics of vitreoretinal surgery.

Amniotic membrane maintains the phenotype of rabbit retinal pigment epithelial cells in culture.

The success of surgical removal of choroidal neovascularisation followed by transplantation of autologous retinal pigment epithelial cells (RPE) for age-related macular degeneration (ARMD) may be limited by damage in Bruch's membrane. We investigated whether amniotic membrane (AM) might be used as an alternative basement membrane-containing matrix to support RPE growth and differentiation. Primary RPE plastic cultures were established from freshly enucleated Dutch belted rabbit eyes in DMEM/F12 containing 0.1 mM Ca(++) and 10% dialysed FBS. Upon subconfluence, cells were subcultured at 5000-9000 cells cm(-2) in the above-mentioned culture medium on intact AM (iAM), epithelially denuded AM (dAM) or plastic. After confluence, the Ca(++) concentration in the medium was increased to 1.8 mm for 4 weeks. Growth and morphology were monitored by phase contrast microscopy, and the phenotype by immunostaining with antibodies against cytokeratin 18, tight junction protein ZO-1, and RPE65 protein, and by transepithelial resistance (TER) measurement. Immunostaining to cytokeratin 18 confirmed the epithelial origin of isolated cells in both primary culture and subcultures. Compared to plastic cultures, RPE increased pigmentation within 24 hr after seeding on AM, with iAM being more pronounced than dAM. RPE adopted a hexagonal epithelial phenotype with more organised pigmentation, strong expression of ZO-1 and RPE65, and a significantly higher TER 4 weeks after Ca(++) switch on dAM. Our results indicate that AM may be used as a basement membrane-containing matrix to maintain RPE phenotype in vitro, and may facilitate subsequent transplantation to treat ARMD.

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.