Practice patterns of corneal transplantation in Europe: first report by the European Cornea and Cell Transplantation Registry.

PURPOSE: To report practice patterns of corneal transplantation in Europe. SETTING: Corneal clinics in 10 European member states (MS), the United Kingdom, and Switzerland. DESIGN: Multinational registry study. METHODS: Corneal transplant procedures registered in the European Cornea and Cell Transplantation Registry were identified. Preoperative donor and recipient characteristics, indication and reason for transplantation, and surgical techniques were analyzed. RESULTS: A total of 12 913 corneal transplants were identified from 10 European Union MS, the United Kingdom, and Switzerland. Most countries were self-sufficient with regard to donor tissue. Fuchs endothelial corneal dystrophy was the most common indication (41%, n = 5325), followed by regraft (16%, n = 2108), pseudophakic bullous keratopathy (12%, n = 1594), and keratoconus (12%, n = 1506). Descemet stripping automated endothelial keratoplasty (DSAEK, 46%, n = 5918) was the most commonly performed technique, followed by penetrating keratoplasty (30%, n = 3886) and Descemet membrane endothelial keratoplasty (9%, n = 1838). Vision improvement was the main reason for corneal transplantation (90%, n = 11 591). Surgical technique and reason for transplantation differed between indications. CONCLUSIONS: This report provides the most comprehensive overview of corneal transplantation practice patterns in Europe to date. Fuchs endothelial dystrophy is the most common indication, vision improvement the leading reason, and DSAEK the predominant technique for corneal transplantation.

Ultrastructural Analysis of Rehydrated Human Donor Corneas After Air-Drying and Dissection by Femtosecond Laser.

Purpose: To evaluate the efficiency of femtosecond laser (FSL) incision of rehydrated human donor corneas after air-drying and its effects on corneal structure. Methods: We compared the rehydrated and fresh-preserved corneas by microscopy following Victus-Tecnolas FSL treatment for straight-edge anterior lamellar keratoplasty (ALK). The corneas were dehydrated at room temperature under a laminar-flow hood. Results: To obtain the horizontal cut in rehydrated corneas, we increased the FSL pulse energy to 1.2 µJ from 0.80 µJ applied for the fresh corneas and obtained a clear-cut separation of the lamellar lenticule cap from the corneal bed. Light microscopy showed regular arrangement of stromal collagen lamellae, with spaces in between the fibers in the corneal stroma in the fresh and the rehydrated corneas, but the uppermost epithelial layers in the rehydrated corneas were lost. Transmission electron microscopy (TEM) revealed no signs of thermal or mechanical damage to the corneal structure. The epithelial basal membrane and Bowman's layer maintained their integrity. The epithelial basal layer and cells were separated by large spaces due to junction alteration in the rehydrated corneas. There were gaps between the lamellar layers in the stroma, especially in the rehydrated corneas. Keratocytes displayed normal structure in the fresh corneas but were devoid of microorganules in the rehydrated corneas. Minor irregularities were observed in the vertical incision and the horizontal stroma appeared smooth on scanning electron microscopy. Conclusion: The corneal stroma of rehydrated corneas maintained morphology and integrity, while corneal cellular components were generally altered. When corneas are intended for FSL-assisted ALK, effective stromal bed incision is best achieved at a laser power higher than that currently adopted for fresh corneas.

Outcomes of corneal transplantation in Europe: report by the European Cornea and Cell Transplantation Registry.

PURPOSE: To analyze real-world graft survival and visual acuity outcomes of corneal transplantation in Europe. SETTING: Corneal clinics in 10 European Union member states, the United Kingdom, and Switzerland. DESIGN: Multinational registry study. METHODS: All corneal transplant procedures registered in the European Cornea and Cell Transplantation Registry (ECCTR) were identified. Graft survival of primary corneal transplants were analyzed using Kaplan-Meier survival curves with log-rank test and Cox regression. Corrected distance visual acuities (CDVAs) are reported at baseline and 2 years postoperatively using the Lundström distribution matrix. RESULTS: A total of 12 913 corneal transplants were identified. Overall, 32-year graft survival of corneal transplants was high (89%) but differed between indications, ranging from 98% in keratoconus and 80% for trauma. Overall, CDVA improved postoperatively, but the risk for losing vision ranged from 7% (baseline vision ≤0.1 Snellen) to 58% (baseline vision ≥1.0 Snellen). CONCLUSIONS: This report provides a comprehensive overview of graft survival and visual outcomes of corneal transplantation in Europe. In addition, it provides real-world estimates of outcomes for a variety of indications and surgical techniques to support benchmarking and demonstrates the relationship between baseline and postoperative vision.

Parental Perceptions of Obesity and Obesity Risk Associated With Childhood Acute Lymphoblastic Leukemia.

The prevalence of obesity and related comorbidities in survivors of childhood acute lymphoblastic leukemia (ALL) is well established and ranges anywhere from 29% to 69% depending on the study. We sought to explore the awareness of parents of survivors of childhood ALL regarding the increased risk of obesity and their perceptions regarding the overall health of their child. One hundred twenty-one parents of 99 survivors of pediatric ALL completed surveys regarding perceptions of obesity risk in survivors. Eighty percent of parents of overweight and obese survivors correctly identified their child as "a little overweight" or "overweight." Few parents recalled discussing weight gain (21%) or obesity risk (36%) with their practitioner. Parents that did recall having these discussions and/or reported a decreased level of posttherapy activity in their child were more likely to be concerned about their child's weight status. Improved awareness and education regarding the risk of obesity and associated comorbid conditions may provide an avenue for future prevention of obesity in survivors of pediatric ALL. Discussion and education regarding a healthy lifestyle, including proper diet and exercise, should be incorporated early in routine patient visits.

Amniotic membrane in ophthalmology: properties, preparation, storage and indications for grafting-a review.

The use of amniotic membrane in ophthalmic surgery and other surgical procedures in the fields of dermatology, plastic surgery, genitourinary medicine and otolaryngology is on the increase. Furthermore, amniotic membrane and its epithelial and mesenchymal cells have broad use in regenerative medicine and hold great promise in anticancer treatment. Amniotic membrane is a rich source of biologically active factors and as such, promotes healing and acts as an effective material for wound dressing. Amniotic membrane supports epithelialization and exhibits anti-fibrotic, anti-inflammatory, anti-angiogenic and anti-microbial features. Placentas utilised in the preparation of amniotic membrane are retrieved from donors undergoing elective caesarean section. Maternal blood must undergo serological screening at the time of donation and, in the absence of advanced diagnostic testing techniques, 6 months postpartum in order to cover the time window for the potential transmission of communicable diseases. Amniotic membrane is prepared by blunt dissection under strict aseptic conditions, then is typically transferred onto a nitrocellulose paper carrier, usually with the epithelial side up, and cut into multiple pieces of different dimensions. Amniotic membrane can be stored under various conditions, most often cryopreserved in glycerol or dimethyl sulfoxide or their mixture with culture medium or buffers. Other preservation methods include lyophilisation and air-drying. In ophthalmology, amniotic membrane is increasingly used for ocular surface reconstruction, including the treatment of persistent epithelial defects and non-healing corneal ulcers, corneal perforations and descemetoceles, bullous keratopathy, as well as corneal disorders with associated limbal stem cell deficiency, pterygium, conjunctival reconstruction, corneoscleral melts and perforations, and glaucoma surgeries.

Ethical Issues in Transnational Eye Banking.

PURPOSE: To review ethical issues that may arise in the setting of transnational eye banking activities, such as when exporting or importing corneal tissue for transplantation. METHODS: A principle-based normative analysis of potential common dilemmas in transnational eye banking activities was performed. RESULTS: Transnational activities in eye banking, like those in other fields involving procurement and use of medical products of human origin, may present a number of ethical issues for policy makers and professionals. Key ethical concerns include the potential impact of export or import activities on self-sufficiency of corneal tissue supply within exporting and importing countries; potential disclosure requirements when obtaining consent or authorization for ocular tissue donation when donations may be exported; and difficulties inherent in assuring equity in the allocation of tissues available for export and in establishing and respecting standards of safety and quality across different jurisdictions. CONCLUSIONS: Further analysis of specific ethical issues in eye banking is necessary to inform development of guidelines and other governance tools that will assist policy makers and professionals to support ethical practice.

Quality of life changes over time in patients with chronic obstructive pulmonary disease.

PURPOSE OF REVIEW: Chronic obstructive pulmonary disease (COPD) is often considered to be a disease in which an inevitable decline in lung function results in increasing dyspnea and deteriorating quality of life. This review summarizes recent data that calls this classic paradigm into question. Studies evaluating the effects of chronic sputum production, physical activity, and inhaled medications on quality of life and prognosis are also discussed. RECENT FINDINGS: Chronic sputum production and level of dyspnea contribute at least as much to impairment of quality of life and prognosis as does abnormal lung function. An accelerated decline in FEV1 occurs in only half of the patients who develop COPD. Current pharmacotherapy has been shown to moderate disease progression and quality of life, although the effects are lost when inhaled corticosteroids are discontinued. Declining physical activity begins early in the course of COPD, but increasing activity levels result in improved quality of life and a slower decline in lung function. SUMMARY: Symptoms and activity levels are as important as measuring FEV1 in determining disease severity, quality of life, and prognosis of COPD. Therapies exist that moderate the course of the disease, and small sustained increases in physical activity may slow physical deterioration and improve health-related quality of life.

Spectral and temporal analysis of simulated dead regions in cochlear implants.

A cochlear implant (CI) electrode in a "cochlear dead region" will excite neighboring neural populations. In previous research that simulated such dead regions, stimulus information in the simulated dead region was either added to the immediately adjacent frequency regions or dropped entirely. There was little difference in speech perception ability between the two conditions. This may imply that there may be little benefit of ensuring that stimulus information on an electrode in a suspected cochlear dead region is transmitted. Alternatively, performance may be enhanced by a broader frequency redistribution, rather than adding stimuli from the dead region to the edges. In the current experiments, cochlear dead regions were introduced by excluding selected CI electrodes or vocoder noise-bands. Participants were assessed for speech understanding as well as spectral and temporal sensitivities as a function of the size of simulated dead regions. In one set of tests, the normal input frequency range of the sound processor was distributed among the active electrodes in bands with approximately logarithmic spacing ("redistributed" maps); in the remaining tests, information in simulated dead regions was dropped ("dropped" maps). Word recognition and Schroeder-phase discrimination performance, which require both spectral and temporal sensitivities, decreased as the size of simulated dead regions increased, but the redistributed and dropped remappings showed similar performance in these two tasks. Psychoacoustic experiments showed that the near match in word scores may reflect a tradeoff between spectral and temporal sensitivity: spectral-ripple discrimination was substantially degraded in the redistributed condition relative to the dropped condition while performance in a temporal modulation detection task degraded in the dropped condition but remained constant in the redistributed condition.

Practice patterns of stroke screening and hydroxyurea use in children with sickle cell disease: a survey of health care providers.

Incidence of stroke in sickle cell disease (SCD) has declined with the use of transcranial Doppler ultrasound and chronic transfusion therapy. There is little information regarding their use in genotypes other than HbSS and HbSß. Silent cerebral infarcts (SCIs) have been identified by magnetic resonance imaging (MRI) in SCD patients and it is believed that these may increase the risk of overt stroke. No evidence-based guidelines exist regarding MRI screening for SCIs. Hydroxyurea is a standard therapy in patients with history of acute chest syndrome and severe, recurrent, SCD-associated pain episodes, but has not been established for use with other sickle-associated morbidities. A total of 102 institutions received a survey (with 62 responses) to assess the use of transcranial Doppler ultrasound for stroke screening, use of screening MRI for SCIs, and institutional patterns for prescribing hydroxyurea. Nineteen percent of institutions screen genotypes other than HbSS and HbSß, and 24% use MRI to screen for SCIs. Twenty-six percent of institutions prescribed hydroxyurea in patient found to have SCIs. Results indicate significant variation in stroke screening and hydroxyurea use often correlating with clinic size, number of physician providers, and geographic location. There are currently no evidence-based guidelines to support many of these practices.

An unusual case of rapidly progressive hyperbilirubinemia.

We present an unusual case of hyperbilirubinemia with rapid early progression leading to bilirubin encephalopathy in a term neonate. Despite early recognition and intervention, the total serum bilirubin reached a maximum level of 39 mg/dL at 32 hours of life. Prior to an emergent exchange transfusion, the patient's diagnostic evaluation was significant for Coombs-negative microangiopathic hemolytic anemia and thrombocytopenia. Further testing revealed a deficiency of ADAMTS13 protein, or von Willebrand factor-cleaving protease, a finding diagnostic of congenital thrombotic thrombocytopenic purpura, or Upshaw-Schulman syndrome. This rare disease is often misdiagnosed, especially in the newborn period.

Relationship between channel interaction and spectral-ripple discrimination in cochlear implant users.

Cochlear implant (CI) users can achieve remarkable speech understanding, but there is great variability in outcomes that is only partially accounted for by age, residual hearing, and duration of deafness. Results might be improved with the use of psychophysical tests to predict which sound processing strategies offer the best potential outcomes. In particular, the spectral-ripple discrimination test offers a time-efficient, nonlinguistic measure that is correlated with perception of both speech and music by CI users. Features that make this "one-point" test time-efficient, and thus potentially clinically useful, are also connected to controversy within the CI field about what the test measures. The current work examined the relationship between thresholds in the one-point spectral-ripple test, in which stimuli are presented acoustically, and interaction indices measured under the controlled conditions afforded by direct stimulation with a research processor. Results of these studies include the following: (1) within individual subjects there were large variations in the interaction index along the electrode array, (2) interaction indices generally decreased with increasing electrode separation, and (3) spectral-ripple discrimination improved with decreasing mean interaction index at electrode separations of one, three, and five electrodes. These results indicate that spectral-ripple discrimination thresholds can provide a useful metric of the spectral resolution of CI users.

Studies on bilateral cochlear implants at the University of Wisconsin's Binaural Hearing and Speech Laboratory.

This report highlights research projects relevant to binaural and spatial hearing in adults and children. In the past decade we have made progress in understanding the impact of bilateral cochlear implants (BiCIs) on performance in adults and children. However, BiCI users typically do not perform as well as normal hearing (NH) listeners. In this article we describe the benefits from BiCIs compared with a single cochlear implant (CI), focusing on measures of spatial hearing and speech understanding in noise. We highlight the fact that in BiCI listening the devices in the two ears are not coordinated; thus binaural spatial cues that are available to NH listeners are not available to BiCI users. Through the use of research processors that carefully control the stimulus delivered to each electrode in each ear, we are able to preserve binaural cues and deliver them with fidelity to BiCI users. Results from those studies are discussed as well, with a focus on the effect of age at onset of deafness and plasticity of binaural sensitivity. Our work with children has expanded both in number of subjects tested and age range included. We have now tested dozens of children ranging in age from 2 to 14 yr. Our findings suggest that spatial hearing abilities emerge with bilateral experience. While we originally focused on studying performance in free field, where real world listening experiments are conducted, more recently we have begun to conduct studies under carefully controlled binaural stimulation conditions with children as well. We have also studied language acquisition and speech perception and production in young CI users. Finally, a running theme of this research program is the systematic investigation of the numerous factors that contribute to spatial and binaural hearing in BiCI users. By using CI simulations (with vocoders) and studying NH listeners under degraded listening conditions, we are able to tease apart limitations due to the hardware/software of the CI systems from limitations due to neural pathology.

Evidence of across-channel processing for spectral-ripple discrimination in cochlear implant listeners.

Spectral-ripple discrimination has been used widely for psychoacoustical studies in normal-hearing, hearing-impaired, and cochlear implant listeners. The present study investigated the perceptual mechanism for spectral-ripple discrimination in cochlear implant listeners. The main goal of this study was to determine whether cochlear implant listeners use a local intensity cue or global spectral shape for spectral-ripple discrimination. The effect of electrode separation on spectral-ripple discrimination was also evaluated. Results showed that it is highly unlikely that cochlear implant listeners depend on a local intensity cue for spectral-ripple discrimination. A phenomenological model of spectral-ripple discrimination, as an "ideal observer," showed that a perceptual mechanism based on discrimination of a single intensity difference cannot account for performance of cochlear implant listeners. Spectral modulation depth and electrode separation were found to significantly affect spectral-ripple discrimination. The evidence supports the hypothesis that spectral-ripple discrimination involves integrating information from multiple channels.

A cocktail party model of spatial release from masking by both noise and speech interferers.

A mathematical formula for estimating spatial release from masking (SRM) in a cocktail party environment would be useful as a simpler alternative to computationally intensive algorithms and may enhance understanding of underlying mechanisms. The experiment presented herein was designed to provide a strong test of a model that divides SRM into contributions of asymmetry and angular separation [Bronkhorst (2000). Acustica 86, 117-128] and to examine whether that model can be extended to include speech maskers. Across masker types the contribution to SRM of angular separation of maskers from the target was found to grow at a diminishing rate as angular separation increased within the frontal hemifield, contrary to predictions of the model. Speech maskers differed from noise maskers in the overall magnitude of SRM and in the contribution of angular separation (both greater for speech). These results were used to develop a modified model that achieved good fits to data for noise maskers (ρ=0.93) and for speech maskers (ρ=0.94) while using the same functions to describe separation and asymmetry components of SRM for both masker types. These findings suggest that this approach can be used to accurately model SRM for speech maskers in addition to primarily "energetic" noise maskers.

Effect of age at onset of deafness on binaural sensitivity in electric hearing in humans.

Sensitivity to binaural cues was studied in 11 bilateral cochlear implant users, all of whom received both of their cochlear implants as adults, but who varied in the age at onset of deafness, from pre-lingual to childhood-onset to adult-onset. Sensitivity to interaural timing difference (ITD) and interaural level difference (ILD) cues was measured at basal, middle, and apical pitch-matched places of stimulation along the cochlear arrays, using a stimulation rate of 100 Hz. Results show that there is a trend for people whose onset of deafness occurred during adult life or late childhood to retain at least some sensitivity to ITDs, whereas people with onset of deafness earlier in life were insensitive to ITDs. In contrast, ILD cue sensitivity was present in all subjects. There were no effects of place of stimulation on binaural sensitivity, suggesting that there is no indication of a dependence of ITD sensitivity on apical vs basal electrode location.

European eye bank association.

BACKGROUND: The European Eye Bank Association (EEBA) is a technical-scientific organization for eye banks. Founded in 1989 with the simple objective of sharing information on eye banking, the Association is today the leading pan-national association in Europe dedicated to the advancement of eye banking and an authoritative reference point for eye banks which work according to quality standards. METHODS: The Association establishes and maintains an agreed set of medical and technical standards, promotes the collection of data on eye bank activities and processes, provides opportunities for the discussion of all aspects of eye banking practice, including eye donor selection and procurement, relevant research and development, education and training in eye banking, and maintains linkage with national and international corneal transplant communities and relevant bodies. RESULTS: The recent introduction of a more structured and focused committee, a permanent secretariat, the development of a website has enabled the Association to establish closer links and collaborative activities with key regulatory bodies and to provide a more constant exchange of clinical, scientific and technical ideas and best practice with fellow professionals by means of its annual meetings, the EEBA directory and website, and a regular newsletter. CONCLUSION: The EEBA is a scientific organization committed to defining minimum standards and to encouraging eye banks to maintain the highest possible standards for quality and safety. Through its annual meetings, and the collection and exchange of detailed information from member eye banks, the Association can rightly claim to speak with a confident and representative voice on eye banking in Europe.

Quality management in European eye banks.

BACKGROUND: The European Directive on setting standards of quality and safety for human tissues and cells obliges tissue establishments to implement a quality management system (QMS), based on the principles of good practice, in order to assure a high level of protection with regard to the health of recipients of human tissues. METHODS: A systematic approach to quality management should be used and sustained. Although a number of quality systems can be employed, a recommended reference model is the ISO 9001:2000 standard which is particularly relevant to eye banking as it can be implemented to cover the entire donation-transplantation process to ensure that the tissues distributed, and services offered, by eye banks show uniform safety and quality. RESULTS: The adoption and correct management of a QMS is essential to maximise the benefits and minimise the risks for all those involved in the process. The performance and results of this system must be monitored and measured by appropriate parameters/indicators (positive and negative) which pertain to the structure (personnel, facilities, instruments), the process (the sequence of activities), the outcome (recipient health status or client satisfaction), the efficiency (the costs incurred to produce a certain outcome) and the effectiveness (frequency that the required results are attained). CONCLUSION: Careful attention must be paid to all aspects of the quality of donor tissues in order to maintain confidence in their safety and effectiveness. A well-managed QMS is a valuable and effective instrument to guarantee the required high standards for the donation, procurement, testing, processing, storage, distribution and traceability of ocular tissues as well as to facilitate the continuous improvement and the attainment of the objectives of an eye bank.

Interaural time-delay sensitivity in bilateral cochlear implant users: effects of pulse rate, modulation rate, and place of stimulation.

Electrical interaural time delay (ITD) discrimination was measured using 300-ms bursts applied to binaural pitch matched electrodes at basal, mid, and apical locations in each ear. Six bilateral implant users, who had previously shown good ITD sensitivity at a pulse rate of 100 pulses per second (pps), were assessed. Thresholds were measured as a function of pulse rate between 100 and 1,000 Hz, as well as modulation rate over that same range for high-rate pulse trains at 6,000 pps. Results were similar for all three places of stimulation and showed decreasing ITD sensitivity as either pulse rate or modulation rate increased, although the extent of that effect varied across subjects. The results support a model comprising a common ITD mechanism for high- and low-frequency places of stimulation, which, for electrical stimulation, is rate-limited in the same way across electrodes because peripheral temporal responses are largely place invariant. Overall, ITD sensitivity was somewhat better with unmodulated pulse trains than with high-rate pulse trains modulated at matched rates, although comparisons at individual rates showed that difference to be significant only at 300 Hz. Electrodes presenting with the lowest thresholds at 600 Hz were further assessed using bursts with a ramped onset of 10 ms. The slower rise time resulted in decreased performance in four of the listeners, but not in the two best performers, indicating that those two could use ongoing cues at 600 Hz. Performance at each place was also measured using single-pulse stimuli. Comparison of those data with the unmodulated 300-ms burst thresholds showed that on average, the addition of ongoing cues beyond the onset enhanced overall ITD sensitivity at 100 and 300 Hz, but not at 600 Hz. At 1,000 Hz, the added ongoing cues actually decreased performance. That result is attributed to the introduction of ambiguous cues within the physiologically relevant range and increased dichotic firing.

Role of masker predictability in the cocktail party problem.

In studies of the cocktail party problem, the number and locations of maskers are typically fixed throughout a block of trials, which leaves out uncertainty that exists in real-world environments. The current experiments examined whether there is (1) improved speech intelligibility and (2) increased spatial release from masking (SRM), as predictability of the number/locations of speech maskers is increased. In the first experiment, subjects identified a target word presented at a fixed level in the presence of 0, 1, or 2 maskers as predictability of the masker configuration ranged from 10% to 80%. The second experiment examined speech reception thresholds and SRM as (a) predictability of the masker configuration is increased from 20% to 80% and/or (b) the complexity of the listening environment is decreased. In the third experiment, predictability of the masker configuration was increased from 20% up to 100% while minimizing the onset delay between maskers and the target. All experiments showed no effect of predictability of the masker configuration on speech intelligibility or SRM. These results suggest that knowing the number and location(s) of maskers may not necessarily contribute significantly to solving the cocktail party problem, at least not when the location of the target is known.

Screening the phytoremediation potential of desert broom (Baccharis sarothroides Gray) growing on mine tailings in Arizona, USA.

The metal concentrations in a copper mine tailings and desert broom (Baccharis sarothroides Gray) plants were investigated. The metal concentrations in plants, soil cover, and tailings were determined using ICP-OES. The concentration of copper, lead, molybdenum, chromium, zinc, arsenic, nickel, and cobalt in tailings was 526.4, 207.4, 89.1, 84.5, 51.7, 49.6, 39.7, and 35.6mgkg(-1), respectively. The concentration of all elements in soil cover was 10-15% higher than that of the tailings, except for molybdenum. The concentration of copper, lead, molybdenum, chromium, zinc, arsenic, nickel, and cobalt in roots was 818.3, 151.9, 73.9, 57.1, 40.1, 44.6, 96.8, and 26.7mgkg(-1) and 1214.1, 107.3, 105.8, 105.5, 55.2, 36.9, 30.9, and 10.9mgkg(-1) for shoots, respectively. Considering the translocation factor, enrichment coefficient, and the accumulation factor, desert broom could be a potential hyperaccumulator of Cu, Pb, Cr, Zn, As, and Ni.