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PubMed2006

What the patient wore, and why ...

This study set out to compare the wearing habits and attitudes of patients today with those, featured in a study by Cross, fitted prior to 1949. Information was sought in the present time regarding the age, occupation and sex of the wearers in 10 different categories of lens types currently available. The views of the patients were also sought regarding the comfort, distance vision, close vision, convenience and how the present lenses met their expectations. Motivation to wear contact lenses was also compared between the two studies. Results show a considerable change in the age of wearers both at the time of fitting and at the time of the studies, occupations of the wearers, and wearing modalities. Most of all it highlights the huge amount of choice available to the modern wearer, not only in lens types and materials, but also in the location and type of practice fitting lenses now at very much lower costs. Wearing times tend to have dropped since 1949 but through choice rather than necessity.

Adolescent↗

PubMed2003

Contact lens fitting for post-radial-keratotomy residual myopia.

PURPOSE: To formulate guidelines for contact lens fitting following radial keratotomy and to achieve a relationship between contact lens fitting parameters and refractive and keratometric parameters. METHODS: Thirty-five eyes of 30 patients who had post-radial-keratotomy residual myopia were evaluated for contact lens fitting. The base curve was selected by 'hit and trial' method until a proper fit was achieved, following which an over-refraction was done and final power of the contact lens obtained. RESULTS: The mean contact lens base curve was 43.04 +/- 1.62 D, which was steeper than the postoperative keratometry by 2.35 +/- 0.74 D. The base curve and the postoperative keratometry were correlated by regression analysis (r = 0.895, P < 0.001). The mean overall diameter of the contact lenses was 9.64 +/- 0.08 mm. The mean contact lens power was 5.81 +/- 3.07 D, which was more myopic than the residual myopia by 2.79 +/- 1.67 D. Regression analysis showed definite correlation between the contact lens power and postoperative myopia (r = 0.854, P < 0.001). CONCLUSION: For correction of post-radial-keratotomy residual myopia, contact lens fitting parameters can be determined by a regression formula using keratometric and refractive values.

Adult↗

PubMed1994

Effect of prescribed prism on monocular interpupillary distances and fitting heights for progressive add lenses.

Success in fitting progressive addition lenses is dependent upon the accurate placement of the progressive zone. Both eyes must track simultaneously within the boundary of the progressive corridor. Vertical prism will displace the wearer's lines of sight and consequently eye position. Because fitting heights are measured using an empty frame, subjects with vertical phorias usually will fuse, and not show the vertical differences in pupil heights during the measuring process. Therefore, when prescriptions contain vertical prism one must consider the changes in measured fitting heights that will occur once the lenses are placed in the frame. Fitting heights must be altered approximately 0.3 mm for each vertical prism diopter prescribed. The fitting height adjustment is opposite from the base direction of the prescribed prism. An explanation of the effect of prescribed horizontal prism on monocular interpupillary distance (PD) measurements is also included.

Eye↗

PubMed2002

Spectacle fitting with ear, nose and face deformities or abnormalities.

Spectacle frame selection and dispensing remain significant components of optometry. Occasionally, we encounter patients who are unable to wear conventional spectacles due to abnormalities or deformities following injury and/or surgery to their nose, ears or head. In these cases, spectacle frame fitting may be more complex and customized frame adjustments may be required to account for the anatomical variations. A patient with a microtia (hypoplastic pinna) was fitted with a tailored spectacle frame. The details are presented together with a summary of different frames and modifications available for ears, nose and face abnormalities.

Adolescent↗

PubMed2003

Hearing aid fitting: application of telemedicine in audiology.

Telemedicine is used as a tool for therapeutic performances with the aid of telematics. The term telematics, a compound of the words telecommunication and informatics, means (in general) electronic transfer of digital data. We describe an application of telemedicine in the field of audiology: the initial fitting, setup, fine tuning, and follow-up fitting of all kinds of digital programmable and digital signal-processing devices and the fitting of hearing aids in real soundscapes. Against a backdrop of limited resources and continuous innovations, telemedicine offers the possibility of increasing the efficiency of audiological methods and decreasing expenses at the same time.

Audiology↗

PubMed2005

The significance of marginal gap and overextension measurement in the evaluation of the fit of complete crowns.

INTRODUCTION: An important criterion for the success of a crown is marginal fit. However, in the patient's mouth fit can only be evaluated by subjective methods. This study describes the correlation between objective marginal fit and its subjective evaluation by dentists and dental technicians. MATERIALS AND METHODS: Thirty human premolars and molars were randomly divided into six groups and prepared with a shoulder. For each of the six groups, complete crowns were made of different alloys and technologies (casting: AuAgCu, AuPdPt, PdAgAu, CoCrMo, and Ti; milling: Ti). The crowns were cemented with provisional cement. Ten dentists and 10 technicians were asked to evaluate the fit of the crowns with a new dental explorer. The crowns were then cleaned and cemented with a zinc-oxide-phosphate-cement. The marginal gap and a possible overextended margin of the crowns were examined under a special 4x light microscope with a magnification level of 560 X. The means of the gaps and the overextended margins were calculated for each group. Significances were detected by analysis of variance (ANOVA) and the post-hoc-test (Bonferroni, p<0.05). Correlations between objective measuring and subjective evaluation were evaluated using the Pearson test. The influence of the measured values on the subjective evaluation was determined by regression analyses. RESULTS: Crowns made from different alloys and technologies showed partly significantly (p<0.05) different marginal gaps (mean ranging from 35 microm to 92 microm) and significantly (p<0.05) different overextended margins (mean ranging from 40 microm to 149 microm). There were significant correlations (p<0.05) between subjective findings and objective data. Significant correlations (p<0.01) were also found between the subjective findings of dentists and technicians. Compared to the marginal gap, only the overextended margin had a significant influence (p=0.00) on the subjective evaluations of the clinicians. CONCLUSION: Crowns from different alloys and technologies showed differences in marginal fit. Marginal gap and the overextension of the crowns significantly correlated with the subjective evaluation of their fit by dentists and dental technicians. For the decision of the clinicians, whether a crown is acceptable, overextension was more important than marginal gap.

Analysis of Variance↗

PubMed1996

Standardized rigid contact lens fitting protocol for keratoconus.

Keratoconus is typically managed by a variety of rigid contact lens fitting techniques and lens designs. The two most fundamental fitting techniques are apical corneal touch (including divided or three-point touch) and apical clearance. In the course of designing a multi-center study of keratoconus patients, a standardized keratoconus fitting protocol was developed. All contact lens parameter options are uniform except for base curve and secondary curve radii, which are determined by interpretation of fluorescein patterns using the CLEK Study trial lens set and protocol. The initial trial lens's base curve is the average keratometric reading; sequentially steeper lenses are applied until definite apical clearance is observed. We have evaluated the feasibility of this standardized fitting protocol on 30 keratoconus patients. Our results suggest that we have developed a standardized contact lens fitting set and fitting protocol to simplify contact lens management in patients with mild to moderate keratoconus.

Contact Lenses↗

PubMed2006

Correlations between central and peripheral changes in anterior corneal topography after myopic LASIK and their implications in postsurgical contact lens fitting.

PURPOSE: To investigate the changes in central and peripheral anterior corneal curvatures after myopic laser in situ keratomileusis (LASIK) and to correlate them with the manifest refractive change to discuss how such results could affect post-LASIK corneal topography profiles and midterm stability and their implications in postsurgical contact lens fitting. METHODS: Topographic and refractive data from 18 eyes of 11 patients that had undergone myopic LASIK were collected for 6 months after surgery. Short-term and midterm topographic responses were investigated and correlated with spherical equivalent manifest refractive changes. RESULTS: There was a strong correlation between eccentricity changes and manifest refractive change 15 days after surgery (r = 0.753, P < 0.001), with no significant changes thereafter for the following 6 months (r = 0.148, P = 0.114). A strong linear relationship was found between baseline manifest refraction and changes in corneal curvature at the center (r = 0.810, P < 0.001), 4-mm chord (r = 0.895, P < 0.001), and 6-mm chord (r = 0.696, P < 0.001). Statistically significant changes were also found after the first 15 days (P < 0.005) and showed a regression effect that affects the three zones. In this case, a weaker relationship was found between curvature regression and the final refractive change for the central location (r = 0.412, P = 0.004), 4-mm chord area (r = 0.430, P = 0.003), and 6-mm chord area (r = 0.283, P = 0.023). CONCLUSIONS.: After myopic LASIK, the anterior corneal dioptric power is expected to change, on average, approximately 77% of the attempted spherical equivalent correction at the center; 60% at the 4-mm chord region, where the stronger correlation between topographic and refractive change is found; and 30% at the 6-mm chord area. The paracentral area 4 mm from the center seems to be more likely to predict baseline corneal curvature from manifest refractive change. Some degree of regression in the midterm period is expected to occur after myopic LASIK, which shows a significant correlation with the manifest refractive change. Again, this effect is more evident and more accurately predicted at the 4-mm chord area. The results of the current study are of interest for those fitting contact lenses after myopic LASIK.

Adult↗

PubMed1999

Margin gap size of ceramic inlays using second-generation CAD/CAM equipment.

OBJECTIVE: The goal of this study was to determine if the fit of second-generation computer-assisted design/computer-assisted manufacturing (CAD/CAM) (CEREC 2, Sirona Dental Systems, Bensheim, Germany) inlays within Class II cavity preparations were within the range of 50 to 100 microns and were equal or better to CEREC 1 inlays. MATERIALS AND METHODS: Extracted human molars free of surface defects and caries were prepared with standard mesio-occlusodistal cavity preparations. Ceramic inlays were fabricated with CEREC 2 CAD/CAM equipment and seated into cavity preparations. Digital images were captured at 100 times magnification. Marginal gaps were measured with an image analysis program. For each restoration, gaps were measured at 12 locations along interproximal margins and 10 locations along occlusal margins. RESULTS: No difficulty occurred in seating any of the milled inlays. Average marginal gaps for occlusal (59 +/- 35 microns) and interproximal (97 +/- 66 microns) margins were statistically different (t-test, p < or = .01). Average marginal gap for all sites combined was 80 +/- 57 microns. Marginal gap widths were smaller than those obtained from a similar study done earlier with the CEREC 1 unit for occlusal (89 +/- 65 microns) and interproximal (105 +/- 81 microns) margins. Ease of seating with CEREC 2 inlays was much better than with CEREC 1. CLINICAL SIGNIFICANCE: Improvements in software and hardware allow the CEREC 2 to adapt well to standard inlay cavity preparations. The ability of the device to create inlays that seat without interference is remarkable. The improved fit and ability to create the occlusal surface in a variety of ways make CEREC 2 an attractive restorative option for all-ceramic restorations.

Ceramics↗

PubMed1995

Congenital limb anomalies and amputees Tayside, Scotland 1965-1994.

The purpose of this study was to review the 68 patients who had been referred to Dundee Limb Fitting Centre during the period 1965-1994, with a congenital anomaly of a major limb requiring prosthetic replacement. A profile of the incidence of congenital anomalies, amputation levels and prosthetic fitting was obtained. During the period only 68 cases with 80 congenital anomalies were referred. During these 29 years, 20 cases required surgical amputation and overall 35 surgical procedures were performed in these cases, only 3 were in the upper limb. The incidence of upper and lower limb deficiency was similar. The patients represented a small proportion (1.6%) of the patients who were reported to have congenital anomalies. Figures indicated that about 8% of all live/still births have some form of anomaly. Prosthetic fitting and use was successful in all 68 cases but long term life follow-up is necessary to ensure continued prosthetic use.

Amputees↗

PubMed1994

Computer-stimulated test fitting of an implantable hearing aid using implantable hearing aid using three-dimensional CT scans of the temporal bone: preliminary study.

In preparation for future implantation of the implantable middle ear transducer in patients, a method was sought for preoperatively test fitting a model of the device, using computer generated three-dimensional (3-D) temporal bone images derived from spiral computed tomography (CT) data. A 3-D model of the implantable middle ear transducer was designed using NIH Image software on a Macintosh computer. High resolution human temporal bone CT scans were obtained using a spiral CT scanner (Siemens Somatom Plus S). The 3-D transducer model was superimposed onto 3-D reconstructions of the temporal bone using ANALYZE software on a computer graphics workstation (Sun SPARCstation 10), showing the transducer "implanted" in the temporal bone. Measurements were validated using a cadaver temporal bone. This process produced images demonstrating the "fit" of the current transducer design in the mastoid region of the adult temporal bone. It permitted assessment of the proximity of surrounding structures such as the external auditory meatus, dura, or sigmoid sinus. Preliminary cadaver validation measurements confirmed the accuracy of this method. Three-dimensional CT is a feasible method for preoperative planning of the surgical implantation of devices in the temporal bone. This method of 3-D test fitting will be used in the future to determine optimum orientation and size limitations for human implantable devices.

Cochlear Implants↗

PubMed1996

Helical CT scanning for CAD/CAM subperiosteal implant construction.

Subperiosteal implant is the treatment of choice for the fully or partially edentulous atrophic mandible if grafting procedures are not contemplated to give the jaw sufficient available bone for endosseous implants. The main disadvantage of the standard technique for the construction of this implant is that it requires two surgical procedures. However, it is an accepted and proven technique with a long-term survival rate. This paper discusses the use of the CT scan subperiosteal implant, which provides a result similar to that of the standard subperiosteal implant, but requires only one surgical procedure. The accuracy of fit of the CT scan subperiosteal implant is similar to that of the implant fabricated by means of a standard two-surgical-impression technique. New updated CT scan machines use faster helical scanners and offer a great improvement over previous CT scan machines. The new CT scan machines reduce the chance of patient movement, produce a more accurate CT scan, and enable a more accurate model of the mandible or maxilla to be developed. This paper discusses the production of a well-fitting CT scan subperiosteal implant by a trained, knowledgeable, and cooperative team of dentist, CT scan technician, and radiologist, all of whom understand the technical means to achieve their goal.

Alveolar Bone Loss↗

PubMed1998

[Effect of socket preparation on primary stability of an elliptical acetabular component].

The aim of this investigation was to examine, with the aid of a valid micrometric measuring system, the initial stability of an elliptical press-fit acetabular component with regard to the size of the reamer used to prepare the socket, and the depth of reaming. All 10 implanted cups showed marked movement (> 500 microns) at the first loading after implantation. Only the implant with a press-fit of 1 mm and a reaming depth of 2 mm showed small elastic micromovement (< 130 microns) at all three measuring points during cyclic loading. The results indicate that press fit and stability need to be optimized using adequate surgical instrumentation and techniques, and that it is necessary to develop new methods to optimize the cementless anchorage of acetabular components.

Acetabulum↗

PubMed2006

[New aspects of hearing aid fitting in noise-induced hearing loss].

In the past hearing aid fitting frequently turned out to be a problem in patients with noise-induced hearing loss. Selective amplification in the high frequency range and at the same time natural sound and appropriate wearing comfort (open fitting) could not be achieved in numerous cases. Today these problems can be tackled by modern hearing aid technology providing us with efficient feedback suppression algorithms making open fittings possible for many more patients. This development is particularly beneficial for patients with noise-induced hearing loss. Unfortunately, open fitting is in opposition to wearing hearing aids at noisy workplaces. Tight fittings, however, can be used at work if a special listening program for noisy conditions is available. This dilemma is discussed and possible solutions are pointed out.

Germany↗

PubMed1999

Fitting contact lenses after myopic keratomileusis.

PURPOSE: To evaluate the long-term efficacy and results of contact lens fitting following myopic keratomileusis (MKM). SETTING: Department of Ophthalmology, Manhattan Eye, Ear, and Throat Hospital, and Swinger Vision Center, New York, New York, USA. METHODS: Postoperative fitting of contact lenses was studied as part of a prospective evaluation of myopic keratomileusis. In this series, 27 eyes of 20 patients had residual postoperative refractive errors that were corrected with contact lenses. Patients were fit at a mean of 9.4 months after surgery by the trial-lens method. Preoperative keratometry readings and refractions, as well as postoperative keratometry readings, refractions, and contact lens specifications, were recorded and used for fitting. RESULTS: Twenty-six eyes (96%) were fit successfully: 24 (89%) with rigid gas-permeable lenses and 2 (7%) with daily-wear soft lenses. The mean diameter of the rigid lenses was 10.00 mm (range 9.4 to 11.0 mm) and the mean base curve, 8.52 mm (range 7.9 to 9.2 mm). The 2 soft lenses had base curves of 8.6 and 8.9 mm. The mean lens power was -5.24 diopters (D) (range -0.37 to -14.75 D), which was, on average, 4.06 D more myopic than the postoperative spectacle refraction. Postoperative keratometry provided a good starting point for the trial lens. Lenses were tolerated for up to 16 years. One eye, fit with a soft lens, developed significant myopia during the fifth year. CONCLUSION: After lamellar refractive surgery, the topography of the cornea is significantly altered. Although the postoperative keratometry readings are steeper than the actual curvature, they are reasonably reliable for determining the base curve of the initial trial lens, validating the use of conventional methods of fitting rigid contact lenses in patients who have had MKM.

Adolescent↗

PubMedDate not supplied

Coronal plane geometry of the proximal humerus relevant to prosthetic arthroplasty.

Most prosthetic designs for the replacement of the proximal humerus have one head shaft angle and several head sizes allowing limited replication of the anatomy. The necessity for press fit designs to follow the reamed canal adds an additional constraint. To better understand these limitations, this study measures proximal humeral anatomy in relationship to the surgically reamed canal. Measurements were made from radiographs of 21 humeri. Radius of curvature averaged 25.3 mm, head height 18.5 mm, head-shaft angle 40.7 degrees, and offset 9.7 mm. Longer humeri had proportionally larger shafts and larger heads (r = 0.7, p < 0.0005). Proximal humeral anatomy is extremely variable. The relatively fixed geometry of most prosthetic systems limits the surgeon's ability to replicate the original anatomy. As a generalization for existing press fit, modular systems, the surgeon must either position a similarly sized prosthetic articular surface superomedial to that of the original anatomy or use one with less articular surface area.

Aged↗

PubMed1996

Feasibility of fitting contact lenses with apical clearance in keratoconus.

Despite the wide variety of rigid contact lens fitting philosophies for the visual correction of keratoconus, questions remain, including which approach-flat, divided support, or steep-contributes the most toward the preservation of a clear cornea. One goal of the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Pilot Study was to determine the feasibility of managing early keratoconus patients with apical clearance rigid contact lenses. Of 30 keratoconus patients identified with at least 1 nonscarred cornea, 17 patients (30 eyes) were randomly assigned to a steep lens fitting protocol. After trial fitting with a standardized lens design demonstrating minimum apical clearance, lenses were dispensed whose base curve was 0.2 mm steeper than the minimum apical clearance lens. Patients were re-evaluated on a quarterly schedule concluding at 12 months. Changes in keratometry between baseline and 12 months identified unequal steepening of the flat and steep corneal curvatures, suggestive of corneal molding. Best corrected rigid lens visual acuity measures illustrated no significant changes over the course of the study. Clinically significant corneal compromise was transiently observed in some patients. Only 1 of 22 eyes completing the pilot study and fitted with apical clearance developed mild corneal scarring.

Adolescent↗

PubMed2003

RK4 lens fitting for a flap striae in a LASIK patient.

PURPOSE: To present a case in which an RK4 lens was fitted for a patient who developed flap striae resulting from laser-assisted in situ keratomileusis (LASIK). METHODS: Case report. RESULTS: A 44-year-old man underwent uncomplicated LASIK procedure for bilateral myopia and astigmatism. Visually significant flap striae (OS>OD) were noted postoperatively. The flaps were relifted, refloated, and stretched twice in each eye. In addition, OD enhancement laser treatment was performed. Nevertheless, decreased best-corrected visual acuity (OS>OD) persisted. One month after LASIK, the patient was referred to our office for a second opinion and further evaluation. To avoid additional manipulation of the flaps, we used an RK4 lens fitting to achieve a final corrected visual acuity of 20/20 OU. CONCLUSIONS: Persistent, visually significant flap striae following flap, refloating, stretching, and smoothing techniques can make LASIK patients unhappy. An RK4 lens fitting is an alternative method for correcting postoperative irregular astigmatism and to achieve the best-corrected visual acuity.

Adult↗