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At least 703 records · Page 39Linked to original sources
PubMed1998

Contact lens base curve prediction from videokeratography.

PURPOSE: To assess whether the contact lens to cornea-bearing relationship, as determined from the fluorescein pattern, can be predicted from videokeratography. METHODS: Nineteen non-rigid gas permeable (RGP) lens wearers were each tested for fluorescein patterns with a series of seven RGP contact lenses of different base curves, and compared to a theoretical estimate of the fitting relationship from videokeratography. The experimentally determined alignment lens was then compared to the theoretical alignment (TA) value as determined from the central curvature and eccentricity. RESULTS: The mean difference in lens choice between the TA and experimental alignment (EA) values was -0.01 +/- 0.04 mm and between the simulated keratometric (KA) readings and the EA choice was 0.11 +/- 0.05 mm. CONCLUSION: A knowledge of the eccentricity value from videokeratography allowed a better prediction of the base curve to cornea relationship than was provided by only a central corneal measurement.

Adult↗
PubMed2004

Fitting contact lenses for visual rehabilitation after penetrating keratoplasty.

PURPOSE: To determine the optical indications for contact lens wear after corneal transplantation. The type of lenses used, fitting philosophy, visual outcomes, and complications were examined. METHODS: A 4-year retrospective chart review was performed and identified 35 eyes in 30 patients wearing contact lenses for visual rehabilitation after penetrating keratoplasty. RESULTS: The optical indications for contact lens fitting after penetrating keratoplasty were multifactorial and included irregular astigmatism (62.9%), spherical anisometropia (57.1%), and astigmatic anisometropia (54.3%). The average time from surgery to initial contact lens fitting was 18.2 months. Spherical rigid gas-permeable lenses were the most common type of lens used. The mean best-corrected visual acuity improved from less than 20/40 with spectacles alone to better than 20/30 when using a contact lens. Punctal occlusion and lubrication helped to improve contact lens tolerance. Complications associated with contact lens use tended to be minor and responded generally well to conservative treatment measures. CONCLUSION: Contact lenses can improve visual function in patients with irregular astigmatism and anisometropia after penetrating keratoplasty.

Adolescent↗
PubMed1995

Recognition of speech in noise with hearing aids using dual microphones.

Fifty subjects with mild to moderately severe sensorineural hearing loss and prior experience with amplification were evaluated at two sites (25 subjects at each site). Speech recognition in noise scores were measured using the Hearing in Noise Test (HINT) for each subject while wearing binaural behind-the-ear hearing aids allowing switching between two fitting algorithms ("basic" and "party") and two microphone conditions (single microphone omnidirectional and dual-microphone directional). Results revealed an average improvement in signal-to-noise ration (SNR) of 7.4 to 8.5 dB at the two sites for the directional conditions in comparison to the omnidirectional conditions. No significant improvement in SNR was measured between the two fitting algorithms. In addition, the Profile of Hearing Aid Benefit (PHAB) (Site I) and the Abbreviated Profile of Hearing Aid Benefit (APHAB) (Site II) were administered. Results revealed that the benefit scores for background noise and reduced cues (Site I) and background noise and aversiveness of sounds (Site II) were significantly higher than those reported in the established norms. Finally, 76 percent of the subjects of Site I reported that the experimental hearing aids provided "significantly better" or "better" performance than their current hearing aids.

Adult↗
PubMed1998

Comparison of performance with frequency transposition hearing aids and conventional hearing aids.

Four experienced hearing aid users were evaluated using a frequency transposition (TranSonic) hearing system. Following a trial period, the Abbreviated Profile of Hearing Aid Performance (APHAB) and a variety of speech audiometric measures were used to compare the frequency transposition fitting with each subject's conventional hearing aids. A single-subject study design with a series of repeated measures permitted statistical analysis of differences in performance with the various amplification strategies. Two of the four subjects demonstrated statistically significant benefit with the frequency transposition device. Results show the efficacy of frequency transposition in improving speech understanding and quality of life in some individuals with severe-to-profound hearing loss. Overall, results suggest the need for evaluating the benefit of frequency transposition on an individual basis.

Acoustic Stimulation↗
PubMed1997

Effect of prosthetic superstructure accuracy on the osteointegrated implant bone interface.

OBJECTIVE: This study evaluated the biologic result of forces induced by a misfitting prosthetic superstructure on implants placed in a New Zealand white rabbit tibia model. STUDY DESIGN: Nine rabbits had two dental implants placed in both right and left proximal tibias. After 6 weeks, one animal was sacrificed for baseline integration data, and the remaining animals had fitting or misfitting prosthetic superstructures attached to the implants for 12 weeks. Implants were evaluated clinically, radiographically, and histomorphometrically at the scanning electron microscopic level. RESULTS: No clinical, radiographic, or histomorphometric evidence exists of integration failure with implants subjected to superstructure strain, although bone remodeling is noted. CONCLUSIONS: Given the limitations of sample size, animal model used, duration of prosthetic superstructure attachment, and loading confounders possible, the study of prosthetic framework misfit must be evaluated with another animal model, such as an intraoral primate model, to determine the relationship between clinical performance and histologic findings.

Adaptation, Physiological↗
PubMed1994

The long-term use of the SoftPerm lens on pellucid marginal corneal degeneration.

Pellucid marginal corneal degeneration (PMCD) is a corneal degeneration often confused with keratoconus because of the presence of high regular and irregular astigmatism. Vision correction can be achieved with rigid contact lenses, but the asymmetric topographic profile often makes obtaining a stable lens fit difficult. This study describes the fitting and satisfactory daily wear during 4 years of a combination lens design (2 years Saturn II and 2 years SoftPerm) on a patient with PMCD. The lens consisted of a central rigid gas permeable portion surrounded by a soft hydrophilic "skirt." Although the degree of astigmatism was high, 1.6 mm (8.00 D) by keratometry and 12.00 D by refraction, the patient was able to wear the lens comfortably 12 hours per day and achieve visual acuity of 20/20. Routine keratometry, pachymetry, and slit lamp examination showed no significant corneal changes resulting from lens wear.

Astigmatism↗
PubMed1995

Hearing-aid fitting in profoundly hearing-impaired children. Comparison of prescription rules.

Generally, the performance of a hearing-impaired child with his or her hearing aids is the major criterion in selection programmes for cochlear implantation. Thereto, it has to be considered whether the hearing-aid fitting is optimal. For this purpose, methods which prescribe hearing-aid gain are valuable, especially in young preverbal children. Three of these methods were evaluated by comparing the calculated and measured gain as a function of frequency in a selected group of profoundly hearing-impaired children (n = 16), all of whom were successful users of hearing aids. Fair agreement was found for the modified NAL rule applicable in profoundly hearing-impaired subjects and the DSL method (desired sensation level method).

Adolescent↗
PubMed2002

Ultrasound imaging in lower limb prosthetics.

The biomechanical interaction between the residual limb and the prosthetic socket determines the quality of fit of the socket in lower limb prosthetics. An understanding of this interaction and the development of quantitative measures to predict the quality of fit of the socket are important for optimal socket design. Finite-element modeling is used widely for biomechanical modeling of the limb/socket interaction and requires information on the internal and external geometry of the residual limb. Volumetric imaging methods such as X-ray computed tomography, magnetic resonance imaging, and ultrasound have been used to obtain residual limb shape information. Of these modalities, ultrasound has been introduced most recently and its development for visualization in prosthetics is the least mature. This paper reviews ultrasound image acquisition and processing methods as they have been applied in lower limb prosthetics.

Amputation Stumps↗
PubMed2006

[The task of the HNO specialist by Hearing Aid fitting. Part 1: indications, special diagnostic tests, prescription].

The first part of the article deals with the indication of fitting, which mainly is given when the communication is impaired, not only in dialogue with one person, but also in conversation with several persons and in noisy surrounding. Yet, the healthy insurances cover only the expenses if the guidelines on relief-aid are considered, which are exactly listed in this article. Bevor starting the fitting of an Hearing Aid, special diagnostic tests are necessary, such as pure tone audiogram, speech audiogram including dB(opt), freefield measurement in noise, and several retrocochlear tests, as well as tinnitus determination and masking with narrow-band and broad-band noise. Most important is the correct filling in the form "Ohrenärztliche Verordnung einer Hörhilfe", including the necessity of renewal. In addition, it is necessary to accentuate the need of trying out several Hearing Aids and to let the patient know that digital Hearing Aids will not be covered by the health insurance.

Germany↗
PubMed1994

Computed tomography and complete dentures. Morphometric analysis.

Ten edentulous patients who were wearing complete dentures that appeared to be well-fitting clinically but were not satisfactory to the patient, were imaged with the use of direct coronal computed tomography. Sections were selected to pass through the maxillary first molar region to study the relationships between the maxillary denture and the supporting tissues, at rest, in maximal intercuspation, and during simulated function. The radiation dose was minimized by limiting the number of cuts made to seven through the same site in different jaw positions both with and without function. Computed tomography offers useful diagnostic information when evaluating patients who have persistently unresoluable denture problems.

Aged↗
PubMed1997

A modified hearing aid fitting procedure using both real ear and 2cc coupler measurement system.

In order to reduce the test time in real ear hearing-aid fitting for children, the validity of applying the average real ear to coupler differences (RECDs) in prefitting procedure using a 2cc coupler measurement system was evaluated by checking whether the majority of people's RECDs might occur within 5 dB of the average RECDs (N = 116) in each test frequency and age group. The percentages of occurrence were around 90% in test subjects' RECDs in saturation sound pressure levels (SSPLs) and around 70% in gain in each important test frequency. Appropriate test frequencies in prefitting are 500, 1000, 1500 and 2000 Hz.

Adolescent↗
PubMedDate not supplied

An in vitro evaluation of ZiReal abutments with hexagonal connection: in original state and following abutment preparation.

PURPOSE: Laboratory processing of implant-supported prostheses may alter the surface of the abutment in contact with the implant head, with potential repercussions for the interface fit. The purpose of this study was to assess changes at the implant interface of high-strength zirconia ceramic esthetic abutments with a hexagonal connection (ZiReal; 3i/Iimplant Innovations, Palm Beach Gardens, FL) following abutment preparation for single-tooth restorations. MATERIALS AND METHODS: The depth (d) and width (w) of the titanium hexagonal portion of the abutment, the apical diameter of the abutment (D), and the rotational freedom (R) of the abutment were assessed for 20 ZiReal abutments prior to preparation (time 0) and following abutment preparation (time 1) to detect any eventual change of fit of the abutment on the top of the implant hexagon. RESULTS: No significant differences relative to any study parameter (d, w, D, and R) were observed between time 0 and time 1 (P = .9542). DISCUSSION AND CONCLUSIONS: The hexagonal misfit of the titanium machined ZiReal abutment on the implant hexagon may be implicated in screw joint loosening. The results of this report suggest that if all laboratory steps are carefully observed, changes at the implant/ZiReal abutment do not occur. The maintenance of the original features of the ZiReal abutment may reduce the risk of screw loosening.

Ceramics↗
PubMedDate not supplied

Principles and techniques in the use of convexity.

Expected outcomes for a correctly fitted ostomy prosthetic device include sustained, predictable wearing time, protection of the stoma from injury, and maintenance of peristomal skin integrity. To accomplish this, the pouching system must be properly sized and maintain continuous contact with the peristomal skin. Continuous contact is achieved when the faceplate provides a mirror image of the topography of the peristomal plane. Varying degrees of support and convexity of the faceplate are used to fit the unique characteristics of the patient's peristomal plane and stoma. Support can be absent, soft or firm. Convexity is some degree of outward curving of the faceplate. Characteristics of the stoma (i.e., flush, retracted, loop), peristomal plane (i.e., creases, hernia, scarring) and abdomen (i.e., flaccid, soft, or firm) may indicate the need for convexity. Potential problems include mucocutaneous separation, ischemia, laceration, erythema, ecchymosis, and pain if convexity is used inappropriately. Alternatives to convexity include the use of an ostomy belt or surgery. Ongoing, intermittent assessment of the prosthetic is essential to evaluate that the convexity and support have achieved the expected outcomes.

Drainage↗
PubMedDate not supplied

Fitting hearing aids using clinical prefitting speech measures: an evidence-based review.

A systematic review of the literature addressed the question "Is there evidence of a good correlation between unaided prefitting speech measures and aided satisfaction on self-report measures?" This restricted question is only one of several possible questions related to speech measures and hearing aid fittings. The levels of evidence that were accepted included meta-analyses, randomized controlled trials, and nonrandomized intervention studies. Nearly 300 articles and book chapters were identified during the initial search; 220 were eliminated on the basis of their abstracts; and 80 papers and book chapters were reviewed in depth. Five studies met the criteria set forth in this review. No significant correlation between traditional unaided prefitting speech measures and aided satisfaction was found in any of the five studies. One of the studies showed a correlation between the results of a prefitting speech-in-noise test and self-reported aided satisfaction.

Hearing Aids↗
PubMed1996

Effect of patient and lens performance characteristics on peripheral corneal desiccation.

BACKGROUND: The problem of 3 and 9 o'clock staining has been a challenge to rigid lens fitters since the early days of corneal lenses. METHODS: To investigate the features of peripheral corneal desiccation (PCD) in a rigid lens extended wear (RGP EW) population, a study was conducted using 12 subjects known to exhibit significant levels of PCD ("stainers"), and a matched group of individuals who had not shown significant staining with the same lens design ("non-stainers"). Analyses of factors which may be of use in predicting which patients will have problems with PCD were performed to identify differences between groups. RESULTS: Pre-fitting variables that were associated with the tendency for staining included higher levels of conjunctival hyperemia, a longer inter-blink interval, and poorer tear quality (higher levels of tear lipid and debris in the tear film). Variables associated with lens fitting that were predictive of staining susceptibility included poorer lens surface wetting, faster front surface drying time, an increased ratio of blink interval to lens drying time, inferior lens centration, and more variable or erratic lens movement during the blink cycle. CONCLUSIONS: These data suggest the presence of an underlying ocular surface disorder in patients prone to PCD. It is recommended that all patients be monitored for staining on daily wear prior to commencing an extended wear regimen, and that patients displaying clinically significant levels of corneal staining not proceed to extended wear.

Adult↗
PubMedDate not supplied

The effect of cement volume on crown seating.

This in vitro study examined the effect of cement volume on the seating of complete crowns. A spaced complete crown was made to fit a nickel-chromium replica mounted in a cementation jig that allowed static and dynamic seating. The crown was luted 10 times for each group using zinc phosphate cement under an initial static load followed by a dynamic load of 1,500 Hz. Seating was measured by a linear variable differential transducer. Mean vertical discrepancies for the three cement volumes were: completely filled (90.0 +/- 15.2 microns); half filled (42.1 +/- 8.6 microns); and brushed on (27.4 +/- 7.2 microns). Means differed significantly (P < .0005). This study indicated that a thinly brushed-on layer of luting cement gave smaller vertical seating discrepancies than greater volumes of luting cement.

Cementation↗
PubMed2006

Two-eared listening in dynamic situations.

Reports of hearing disabilities, particularly those acoustically and perceptually dynamic circumstances, are associated with compromised binaural capacities. Those disabilities that are compromised largely correspond to the areas where benefits of bilateral fitting over unilateral fitting emerge. The singular exception is for disabilities in "Sound quality and naturalness". When binaural capacities are measured by traditional static masking level difference paradigms, relationships between compromised binaural capacity and self-reports of disability are largely absent. However, when masking level differences are assessed using dynamic parameters that are more representative of the conditions experienced in everyday living then significant associations between binaural capacities and self-reports of disability do emerge. We contend that, for both the self-report domain and the psychoacoustical domain, procedures should be more properly representative of the dynamic environments that listeners are routinely exposed to.

Disability Evaluation↗
PubMed2004

Porous polyethylene orbital implant in the pediatric population.

PURPOSE: To determine the incidence of complications of primary insertion of porous polyethylene orbital implant in the pediatric population. DESIGN: Interventional case series. METHODS: Prospective nonrandomized case series of 36 eyes of 36 patients under age 15 years who underwent primary placement of an anteriorly wrapped spherical porous polyethylene orbital implant from March 1998 to August 2002, with at least 17 months of follow-up. RESULTS: The mean age at the time of surgery was 4.6 years. The histopathologic diagnoses after enucleation included intraocular tumor in 22 patients, phthisis bulbi in eight patients, microphthalmos in three patients, Coats disease in two patients, and ruptured traumatic globe in one patient. Twelve patients (33%) had prior ocular surgery. At the time of enucleation, all patients underwent primary placement of spherical porous polyethylene orbital implant anteriorly wrapped with homologous sclera in 30 patients (83%) and autologous sclera in six patients (17%). The spherical implant size was 16 mm in one patient (3%), 18 mm in 10 patients ( 28%), and 20 mm in 25 patients (69%). The prosthesis was fitted after a mean interval of 5 weeks. After a mean follow-up of 44 months (range, 17 to 68 months), there was one case of pyogenic granuloma (3%) and one case of implant exposure (3%). There were no cases of implant extrusion, superior sulcus syndrome, orbital cellulitis, or significant inflammatory response. No porous polyethylene orbital implant was drilled for peg placement. CONCLUSIONS: Anteriorly wrapped primary porous polyethylene orbital implant in the pediatric population appears to be well tolerated with few complications.

Adolescent↗