[In vitro and in vivo investigations of a modified textile keratoprosthesis. ACTO TexKPRO]. / In-vitro- und In-vivo-Untersuchung einer modifizierten textilen Keratoprothese. ACTO TexKPRO.

BACKGROUND: Clinical application of a keratoprosthesis (KPRO) is still a challenging task. Recent developments reflect the concepts of nut and bolt, intrastromal implantation or an osteoodontokeratoprosthesis (OOKP). A new concept of a textile KPRO has been evaluated in a limited human study with considerable difficulties which after termination of the study and considerable improvements was restarted using animal experiments. MATERIALS: The ACTO TexKPRO is made from polyvinylidene difluoride (PVDF) fibers and transparent silicone. The first and second developmental stages differed in density and size of fibers and furthermore in surface modifications of the fibers and optics which were improved for the second prototype. METHODS: Implantation of the prosthesis was performed in four patients with corneal blindness and in two cases retinal disease which required surgery. In the later animal experiments surgery was performed on three rabbits. Surgery was performed by redressing the conjunctiva, opening of the eyeball with a central 6.5 mm trephination, removal of the lens and iris and implantation and suturing of the TexKPRO. If required a silicone oil endotamponade was placed. RESULTS: All eyes were stable with the keratoprosthesis. The first prototype showed conjunctival recession on the textile haptics with highly susceptible endopthalmitis risk due to infection of the PVDF so that we decided to remove the prosthesis from all eyes after one case of severe endophthalmitis occurred. The longest time of placement was 40 months and the shortest time 6 months. All eyes were restored by keratoplasty. In animals with the new haptic we found better conjunctivalization and stable implantation of the KPRO. DISCUSSION: The textile KPRO provides a stable implantation procedure and safe connection of fibers to the scleral wound bed. The optical and mechanical implantation is safe and stable. Surface epithelialization is improved with the new surface modifications and different PVDF fiber density but beforel new implantations are planned further conceptual changes will be introduced.

[Eye irritation and chemical eye burns. Review of experimental and clinical studies]. / Augenirritation und Augenverätzung. Experimentelle und klinische Übersicht.

Chemical burns of the eye are becoming rare due to improvements in occupational protection. Effective decontamination is the foundation for good clinical results of this ophthalmological emergency. The toxicological aspect focuses on classifying the specific toxicity of a chemical substance by evaluating the degree of eye irritation and eye burns. Chemical substances are classified into defined risk levels by specific tests. The traditional ophthalmological approach is based on the clinical presentation of eye burns as a result of contact with a specific toxic substance. In an integral approach it is shown that substance-specific characteristics, such as concentration and specific reactivity as well as individual features, such as mode and duration of exposition have an influence on the clinical appearance of the tissue damage. The decontamination is dependent on the mode of action and the effectiveness of the decontamination solution. Amphoteric substances have the best effectiveness for decontamination of the eye due to their specific characteristics.

Individual and consensus judgments of disfluency types in the speech of persons who stutter.

Previous research has suggested that the reliability with which judges identify individual disfluency types, such as repetitions or prolongations of speech sounds, may be very poor. The use of disfluency types judgments in research and clinical applications is also complicated by important differences among the several disfluency-based characterizations of stuttered speech. In an attempt to address these problems, this study arranged for 30 judges to identify all disfluency types that they perceived to be present in 5-s audiovisually recorded speech stimuli, each in an Individual task and then with a partner in a Consensus task. Intrapair agreement and interpair agreement for occurrences of disfluency types (from Consensus conditions) were significantly higher than intrajudge and interjudge agreement for occurrences (from Individual conditions). Despite being higher than individual values, however, intrapair and interpair agreement for occurrences both averaged less than 50%. Results also showed that disfluency types judgments, interpreted in terms of three common disfluency-based definitions of stuttering, were not strongly related to previous assessments of whether these speech tokens contained or did not contain stuttering. When combined with previously available data, the present findings suggest caution in the use of disfluency types to describe or define stuttered speech.

Effects of time-interval judgement training on real-time measurement of stuttering.

The purpose of this study was to investigate whether a previously developed interval-based training program could improve judges' stuttering event judgments. Two groups of judges made real-time stuttering event judgments (computer-mouse button presses) in 3 to 6 trials before the response-contingent judgment training program and in another 3 to 6 trials after training, for recordings of 9 adults who stuttered. Their judgments were analyzed in terms of number of stuttering events, duration of stuttering, and 5-s intervals of speech that could be categorized as judged (or not judged) to contain stuttering. Results showed (a) changes in the amount of stuttering identified by the judges; (b) improved correspondence between the judges' identifications of stuttering events and interval-based standards previously developed from judgments made by experienced, authoritative judges; (c) improved correspondence between interval-based analyses of the judges' stuttering judgments and the previously developed standards; (d) improved intrajudge agreement; (e) improved interjudge agreement; and (f) convergence between the 2 judge groups, for samples and speakers used during training tasks and also for other speakers. Some implications of these findings for developing standardized procedures for the real-time measurement of stuttering are discussed.

Identifying the authoritative judgments of stuttering: comparisons of self-judgments and observer judgments.

Reliable and accurate stuttering measurement depends on the existence of unambiguous descriptions or exemplars of stuttered and nonstuttered speech. The development of clinically meaningful and useful exemplars, in turn, requires determining whether persons who stutter judge the same speech to be stuttered that other observers judge to be stuttered. The purpose of these experiments, therefore, was to compare stuttering judgements from several sources: 15 adults who stutter, judging their own spontaneous speech; the same adults who stutter, judging each other's speech; and a panel of 10 authorities on stuttering research and treatment. Judgments were mode under several conditions, including self-judgments made while the speaker was talking and self- and other-judgements made from recordings in continuous and interval formats. Results showed substantial differences in stuttering judgments across speakers, judges, and judgment conditions, but across-task comparisons were complicated by low self-agreement for many judges. Some intervals were judged consistently by all judges to be Stuttered or Nonstuttered, across multiple conditions, but many other intervals were either not assigned replicable judgments or were consistently judged to be Nonstuttered by the speaker who had produced them but were not assigned consistent judgments by other judges. The implications of these findings for stuttering measurement are considered.

Experimental investigation of the effects of frequency-altered auditory feedback on the speech of adults who stutter.

A series of single-subject experiments evaluated the effects of frequency-altered auditory feedback (FAF) on the speech performance of four adult males who stutter. Using alterations of plus or minus one octave, FAF was compared with normal auditory feedback (NAF) in oral reading and spontaneous speech with measurements made of stuttered intervals, stutter-free speech rate, and speech naturalness. The effects of extended FAF conditions on spontaneous speech were also evaluated for two subjects who demonstrated a positive response to FAF. Results showed no consistencies across subjects in responses to FAF: One subject showed no response, another produced an initial temporary response, a third showed a deterioration in speech quality with minimal reductions in stuttering, and a fourth displayed substantial and sustained improvements in speech performance. Some implications of these findings for current research and theory about the relationship between stuttering and FAF are discussed.

Time-interval measurement of stuttering: establishing and modifying judgment accuracy.

The purpose of this study was to determine whether accuracy training for interval judgments of stuttering might generalize to increased accuracy and/or interjudge agreement for intervals other than those used during training. Ten upper-division speech-language pathology students judged 5-s audiovisually recorded speech intervals as stuttered or nonstuttered in a series of group and single-subject experiments. Judgment accuracy was determined with respect to judgments provided previously by 10 recognized authorities on stuttering and its treatment. Training occurred within single-subject experiments that used multiple baselines across speakers and repeated generalization probes to assess training effects. Results showed that judgment accuracy tended to increase after training for speakers used during the training process as well as for unfamiliar speakers. Results also replicated previous findings of slight increases in interjudge and intrajudge agreement after interval-judgment training. The implications of these results for developing a valid and reliable stuttering measurement system are discussed.

Identifying the onset and offset of stuttering events.

This study was designed to investigate the apparent contradiction between recent reports of physiological and interpersonal research on stuttering that claim or imply high agreement levels, and studies of stuttering judgment agreement itself that report much lower agreement levels. Four experienced stuttering researchers in one university department used laser videodisks of spontaneous speech, from persons whose stuttering could be described as mild to severe, to locate the precise onset and offset of individual stuttering events. Results showed a series of interjudge disagreements that raise serious questions about the reliability and validity of stuttering event onset and offset judgments. These results highlight the potentially poor reliability of a measurement procedure that is currently widespread in stuttering research. At the same time, they have isolated some few highly agreed stuttering events that might serve as the basis for the further development of either event-based or interval-based judgment procedures.

Stuttering includes both within-word and between-word disfluencies.

A growing practice divides stuttered disfluencies from normal disfluencies by defining the former as "within-word" and the latter as "between-word." After reviewing the available logical and empirical evidence, this note concludes that the unstated implications of a strong form of this definition (that no between-word disfluencies are stuttering and that all within-word disfluencies are stuttering) cannot currently be supported. A weaker form of this definition might prove useful for the definition and measurement of stuttering, but only if such a definition can be both internally consistent and consistent with available clinical and empirical information.

Judgments of stuttered and nonstuttered intervals by recognized authorities in stuttering research.

The study reported in this paper gathered judgments of stuttering on brief (5.0-sec) audiovisual speech samples taken from six adults who stuttered. Judgments were made by 10 highly experienced authorities on stuttering treatment and research, located in seven different universities or clinical research centers. Results showed considerable agreement between pairs of judges working in the same center, but large and potentially fundamental differences were identified in the amount of stuttering recorded in different centers. Approximately 40% of the 5.0-sec speech intervals used in this study were assigned the same judgment, either Stuttered or Nonstuttered, by all judges on two judgment occasions. The possibility that these intervals may serve as a core for establishing an across-center standard for behavioral judgments of stuttering is discussed.

Time-interval measurement of stuttering: effects of training with highly agreed or poorly agreed exemplars.

This study required six groups of judges, three experimental groups and three control groups (all n = 5), to categorize consecutive 5.0-sec speech intervals as Stuttered or Nonstuttered on four judgment occasions. Between the second and third occasions, each experimental group was trained to categorize correctly one of three sets of speech intervals: agreed intervals, which had been unanimously prejudged to be Stuttered or Nonstuttered; disagreed intervals, which had been prejudged to be Stuttered by approximately half of a large group of judges; or randomly selected intervals, including both agreed and disagreed intervals. Results replicated and extended an earlier finding of improved interjudge agreement for judges trained with highly agreed intervals (Ingham, Cordes, & Gow, 1993): Training with highly agreed intervals was shown to be more effective than equivalent exposure to those intervals without feedback, and training with highly agreed intervals was shown to be more effective than training with, or exposure to, poorly agreed or randomly selected intervals.

Time-interval measurement of stuttering: effects of interval duration.

The study reported in this article used a binary forced-choice judgment procedure to investigate the effects of sample duration on observers' judgements of stuttering. Two groups of judges, differing in their previous experience with stuttering, categorized 270 speech intervals as stuttered or nonstuttered; the intervals were drawn from 30 persons who stuttered and ranged from 1 sec to 15 sec in duration. Results showed that judgments were consistently related to interval duration, with shorter intervals significantly more likely than longer intervals to be labeled nonstuttered. Interjudge agreement levels, however, were largely unaffected by the different interval durations for most speakers and for both judge groups, with the exception of the longest and shortest intervals drawn from speakers evidencing the mildest and most severe stuttering. An interval duration in the 3- to 5-sec region appeared to attract the most satisfactory level of agreement. The implications of these findings for interval-based clinical and experimental measurements of stuttering are discussed.

The reliability of observational data: I. Theories and methods for speech-language pathology.

Much research and clinical work in speech-language pathology depends on the validity and reliability of data gathered through the direct observation of human behavior. This paper reviews several definitions of reliability, concluding that behavior observation data are reliable if they, and the experimental conclusions drawn from them, are not affected by differences among observers or by other variations in the recording context. The theoretical bases of several methods commonly used to estimate reliability for observational data are reviewed, with examples of the use of these methods drawn from a recent volume of the Journal of Speech and Hearing Research (35, 1992). Although most recent research publications in speech-language pathology have addressed the issue of reliability for their observational data to some extent, most reliability estimates do not clearly establish that the data or the experimental conclusions were replicable or unaffected by differences among observers. Suggestions are provided for improving the usefulness of the reliability estimates published in speech-language pathology research.

The reliability of observational data: II. Issues in the identification and measurement of stuttering events.

Much attention has been directed recently toward the problem of measuring occurrences of stuttering with satisfactory levels of interjudge agreement. This paper reviews the prominent concepts of the stuttering event, arguing that they may be one cause of the stuttering measurement problem. The evidence that has led to concerns about the reliability of stuttering event measurements is also reviewed. Reliability and measurement issues that were discussed in the first paper of this series (Cordes, 1994) emerge as basic to the interpretation of much stuttering research, and it is argued that the stuttering measurement problem is not confined to research on stuttering judgments but actually permeates other important stuttering research areas. Some recent attempts to resolve the stuttering measurement problem are reviewed, and the implications of developing an improved measurement system for this disorder are discussed.

Time-interval measurement of stuttering: systematic replication of Ingham, Cordes, and Gow (1993).

The study reported in this paper was designed to replicate and extend the results of an earlier study (Ingham, Cordes, & Gow, 1993) that investigated time-interval judgments of stuttering. Results confirmed earlier findings that interjudge agreement is higher for these interval-recording tasks than has been previously reported for event-based analyses of stuttering judgments or for time-interval analyses of event judgments. Results also confirmed an earlier finding that judges with intrajudge agreement levels of 90% or better show higher interjudge agreement than judges with lower intrajudge agreement scores. This study failed to find differences between audiovisual and audio-only judgment conditions; between relatively experienced and relatively inexperienced student judges; and, most importantly, between the judgments made, and the agreement levels achieved, by judges from two different clinical research settings. The implications of these findings for attempts to develop a reliable measurement method for stuttering are discussed.

Time-interval measurement of stuttering: modifying interjudge agreement.

This paper reports the results of two experiments that investigated interval-by-interval inter- and intrajudge agreement for stuttered and nonstuttered speech intervals (4.0 sec). The first experiment demonstrated that interval-by-interval interjudge agreement could be significantly improved, and to satisfactory levels, by training judges to discriminate between experimenter-agreed intervals of stuttered and nonstuttered speech. The findings also showed that, independent of training, judges with relatively high intrajudge agreement also showed relatively higher interjudge agreement. The second experiment showed that interval-by-interval interjudge agreement was not significantly different if judges rated 4-sec speech intervals from different samples under three conditions: in random order, separated by 5-sec recording intervals; in correct order, also separated by 5-sec recording intervals; or after brief judgment signals that occurred every 4 sec during continuous samples. The implications of these findings for stuttering measurement are discussed.

Time-interval analysis of interjudge and intrajudge agreement for stuttering event judgments.

In response to the recognized need for a valid and reliable way to measure stuttering, this study investigates a measurement methodology based on time-interval analyses of stuttering event judgments. Three groups of judges, differing in stuttering judgment experience, identified stuttering events in 12 repeated presentations of five 1-min speech samples. Fixed time intervals ranging from 0.2 sec to 7.0 sec were then superimposed on the event judgments by a data analysis program. Inter- and intrajudge interval-by-interval agreement, and agreement for total numbers of intervals containing stuttering event judgments, were calculated for each judge group. Results showed that agreement was superior among more experienced judges and in longer interval lengths. Agreement varied across speech samples but not across the repeated judgment opportunities. Agreement was maximized at greater than chance levels for an interval of approximately 3.0 sec, but even this best agreement did not exceed a mean of approximately 60% for experienced judges.

On valid and reliable identification of normal disfluencies and stuttering disfluencies: a response to Aram, Meyers, and Ekelman (1990)

Aram, Meyers, and Ekelman (1990, Brain and Language, 38, 105-121) recently reported finding that children with unilateral brain lesions produced more stuttering-type nonfluencies than their neurologically normal peers. However, they did not report inter- or intrajudge agreement for the nonfluency types or for their method of measuring speech rate. The speech rates they reported were also unusually fast. We argue that these problems with Aram et al.'s study imperil both their results and their conclusions regarding developmental stuttering.