Three different preclinical evaluation methods of MTF through-frequency response, MTF through-focus-response and expected visual acuity were used to compare and analyze the imaging differences of IOLs with four different optical designs. The research work could be used in the simultaneous vision IOLs in the optical design stage and verify the optical quality of the IOLs, the results can predict the visual representation of the patients better. The evaluation results can provide reference for IOL manufacturers and users in product design, development, validation and application selection.
Humans ; Prosthesis Design ; Lenses, Intraocular ; Vision, Ocular ; Visual Acuity

BACKGROUND: The purpose of this study was to investigate the incidence of acromial fracture after reverse total shoulder arthroplasty (RTSA) and clinical and radiological outcomes of treatment of the fracture. METHODS: A systematic review was performed to identify studies that reported the results of treatment of acromial fractures after RTSA. A literature search was conducted by two investigators using four databases (PubMed, Embase, Cochrane, and Ovid Medline). RESULTS: Fifteen studies (2,857 shoulders) satisfied our inclusion criteria. The incidence of acromial fracture after RTSA was 4.0% (114 / 2,857). The mean age of the patients at the time of fracture was 72.9 years (range, 51 to 91 years). The mean time from RTSA to diagnosis of acromial fracture was 9.4 months (range, 1 to 94 months). One hundred shoulders (87.7%) were treated conservatively and 14 shoulders (12.3%) were treated surgically. The mean follow-up period after acromial fracture was 33.8 months. The overall union rate was 50.0% (43.8% for conservative treatment and 87.5% for operative treatment). The fracture incidence was significantly different among the medial glenoid and medial humerus prosthesis design (8.4%), the lateral glenoid and medial humerus design (4.0%), and the medial glenoid and lateral humerus design (2.8%). The mean values at final follow-up were as follows: visual analog scale score, 2.2; American Shoulder and Elbow Surgeons score, 59.1; Constant score, 59.7; and Simple Shoulder Test, 5.8. The mean forward flexion, abduction, and external rotation were 102.3°, 92.3°, and 25.8°, respectively. CONCLUSIONS: Acromial fractures after RTSA are a complication neither uncommon nor negligible. In the absence of studies with high-level evidence, there is a controversy on the outcomes after treatment. Further well-designed prospective randomized controlled studies with a long-term follow-up should be performed to ascertain the diagnosis, treatment, and prognosis of acromial fractures after RTSA.
Acromion ; Arthroplasty ; Diagnosis ; Elbow ; Follow-Up Studies ; Humans ; Humerus ; Incidence ; Prognosis ; Prospective Studies ; Prosthesis Design ; Research Personnel ; Shoulder ; Surgeons ; Visual Analog Scale

Electrical stimulation through retinal prosthesis elicits both short and long-latency retinal ganglion cell (RGC) spikes. Because the short-latency RGC spike is usually obscured by electrical stimulus artifact, it is very important to isolate spike from stimulus artifact. Previously, we showed that topographic prominence (TP) discriminator based algorithm is valid and useful for artifact subtraction. In this study, we compared the performance of forward backward (FB) filter only vs. TP-adopted FB filter for artifact subtraction. From the extracted retinae of rd1 mice, we recorded RGC spikes with 8×8 multielectrode array (MEA). The recorded signals were classified into four groups by distances between the stimulation and recording electrodes on MEA (200-400, 400-600, 600-800, 800-1000 µm). Fifty cathodic phase-1(st) biphasic current pulses (duration 500 µs, intensity 5, 10, 20, 30, 40, 50, 60 µA) were applied at every 1 sec. We compared false positive error and false negative error in FB filter and TP-adopted FB filter. By implementing TP-adopted FB filter, short-latency spike can be detected better regarding sensitivity and specificity for detecting spikes regardless of the strength of stimulus and the distance between stimulus and recording electrodes.
Animals ; Artifacts ; Electric Stimulation ; Electrodes ; Mice ; Retina ; Retinal Ganglion Cells* ; Retinaldehyde* ; Sensitivity and Specificity ; Visual Prosthesis

PURPOSE: To evaluate visual outcomes following implantation of a trifocal diffractive intraocular lens (IOL) and to analyze their correlation with patient satisfaction and ease of performing daily tasks. METHODS: This was a prospective study enrolling 100 eyes of 50 patients undergoing cataract surgery with implantation of trifocal IOL AT LISA tri 839MP. Visual and refractive outcomes were evaluated during a 3-month follow-up. Postoperatively, a questionnaire was used to evaluate patient satisfaction with regard to surgical outcome, spectacle independence, perception of photic phenomena, and ease of performing some vision-related activities. RESULTS: A total of 91%, 87%, and 79% of eyes achieved a monocular uncorrected distance, near, and intermediate visual acuity of 0.1 logarithm of the minimum angle of resolution or better, respectively. After the surgery, 96% of the patients could perform their daily activities without problems. The mean spectacle independence scores for reading, doing computer work, and for distance were 10.33 ± 12.47, 5.71 ± 11.90, and 3.92 ± 9.77, respectively (scale: 0 = no spectacles needed; 40 = spectacles always needed). No correlation was found between spectacle independence and visual outcome (-0.101 ≤ r ≤ 0.244, p ≥ 0.087). Mean scores (0 = no symptoms; 40 = strong symptoms) for glare at night, ghost images, and halos were 15.15 ± 12.02, 4.49 ± 7.92, and 13.34 ± 10.82, respectively. No correlation was found between photic phenomena and visual outcome (-0.199 ≤ r ≤ 0.209, p ≥ 0.150). A total of 80% of patients reported satisfaction with the surgery outcome, and 86% would recommend the surgery to friends and family. CONCLUSIONS: Implantation of the AT LISA tri 839MP IOL after cataract surgery provides effective visual restoration associated with a minimal level of photic phenomena, a positive impact on the performance of vision-related daily activities, and a high level of postoperative patient satisfaction.
Cataract Extraction/*methods ; Eyeglasses ; Female ; Follow-Up Studies ; Humans ; Lens Implantation, Intraocular/*methods ; Male ; Middle Aged ; *Patient Satisfaction ; *Phakic Intraocular Lenses ; Prospective Studies ; Prosthesis Design ; Pseudophakia/*physiopathology ; Refraction, Ocular/*physiology ; Surveys and Questionnaires ; *Visual Acuity

Vision is one of the most important human sensations about the surrounding world. Visual deprivation not only markedly affects the life of blind people, but also gives a heavy burden to their family and the society. A visual prosthesis is an electronic device that helps the blinds to regain visual perception by directly stimulating the visual pathway using the microelectrodes implanted into the body. In recent years, visual prostheses have been developed rapidly and some devices have already become clinically available. In this paper, we reviewed the history of visual prosthesis, introduced different visual prostheses classified according to the location of the implanted stimulating electrodes. Clinical study results as well as the functional status of the currently available visual prosthesis devices were also summarized.
Blindness ; Electrodes, Implanted ; Humans ; Microelectrodes ; Visual Perception ; Visual Prosthesis

A retinal prosthesis is being developed for the restoration of vision in patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Determining optimal electrical stimulation parameters for the prosthesis is one of the most important elements for the development of a viable retinal prosthesis. Here, we investigated the effects of different charge-balanced biphasic pulses with regard to their effectiveness in evoking retinal ganglion cell (RGC) responses. Retinal degeneration (rd1) mice were used (n=17). From the ex-vivo retinal preparation, retinal patches were placed ganglion cell layer down onto an 8x8 multielectrode array (MEA) and RGC responses were recorded while applying electrical stimuli. For asymmetric pulses, 1st phase of the pulse is the same with symmetric pulse but the amplitude of 2nd phase of the pulse is less than 10 microA and charge balanced condition is satisfied by lengthening the duration of the pulse. For intensities (or duration) modulation, duration (or amplitude) of the pulse was fixed to 500 micros (30 microA), changing the intensities (or duration) from 2 to 60 microA (60 to 1000 micros). RGCs were classified as response-positive when PSTH showed multiple (3~4) peaks within 400 ms post stimulus and the number of spikes was at least 30% more than that for the immediate pre-stimulus 400 ms period. RGC responses were well modulated both with anodic and cathodic phase-1st biphasic pulses. Cathodic phase-1st pulses produced significantly better modulation of RGC activity than anodic phase-1st pulses regardless of symmetry of the pulse.
Animals ; Electric Stimulation ; Ganglion Cysts ; Humans ; Macular Degeneration ; Mice* ; Prostheses and Implants ; Retinal Degeneration* ; Retinal Ganglion Cells* ; Retinaldehyde ; Retinitis Pigmentosa ; Visual Prosthesis

PURPOSE: The aim of this review was to analyze the evaluation criteria on mandibular implant overdentures through a systematic review and suggest standardized evaluation criteria. MATERIALS AND METHODS: A systematic literature search was conducted by PubMed search strategy and hand-searching of relevant journals from included studies considering inclusion and exclusion criteria. Randomized clinical trials (RCT) and clinical trial studies comparing attachment systems on mandibular implant overdentures until December, 2011 were selected. Twenty nine studies were finally selected and the data about evaluation methods were collected. RESULTS: Evaluation criteria could be classified into 4 groups (implant survival, peri-implant tissue evaluation, prosthetic evaluation, and patient satisfaction). Among 29 studies, 21 studies presented implant survival rate, while any studies reporting implant failure did not present cumulative implant survival rate. Seventeen studies evaluating peri-implant tissue status presented following items as evaluation criteria; marginal bone level (14), plaque Index (13), probing depth (8), bleeding index (8), attachment gingiva level (8), gingival index (6), amount of keratinized gingiva (1). Eighteen studies evaluating prosthetic maintenance and complication also presented following items as evaluation criteria; loose matrix (17), female detachment (15), denture fracture (15), denture relining (14), abutment fracture (14), abutment screw loosening (11), and occlusal adjustment (9). Atypical questionnaire (9), Visual analog scales (VAS) (4), and Oral Health Impact Profile (OHIP) (1) were used as the format of criteria to evaluate patients satisfaction in 14 studies. CONCLUSION: For evaluation of implant overdenture, it is necessary to include cumulative survival rate for implant evaluation. It is suggested that peri-implant tissue evaluation criteria include marginal bone level, plaque index, bleeding index, probing depth, and attached gingiva level. It is also suggested that prosthetic evaluation criteria include loose matrix, female detachment, denture fracture, denture relining, abutment fracture, abutment screw loosening, and occlusal adjustment. Finally standardized criteria like OHIP-EDENT or VAS are required for patient satisfaction.
Dental Implants ; Denture Rebasing ; Denture, Overlay* ; Dentures ; Female ; Gingiva ; Hemorrhage ; Humans ; Mandibular Prosthesis ; Occlusal Adjustment ; Oral Health ; Patient Satisfaction ; Periodontal Index ; Survival Rate ; Visual Analog Scale ; Surveys and Questionnaires

PURPOSE: To investigate the biometric risk factors for corneal surface complications associated with hydrogel soft contact lens (SCL) fitting in myopic patients in Korea. METHODS: This is a retrospective case-control study. The records of 124 subjects (124 eyes) who wore SCLs on a daily basis were reviewed. Thirty-one patients (31 eyes) who were diagnosed with corneal neovascularization (NV) while wearing SCLs were included in the complication group. Ninety-three age- and sex-matched patients (93 eyes) who wore SCLs, who did not have corneal NV and who visited our clinic for correction of refractive errors were included in the control group. The degree of spherical equivalent, astigmatism and corneal base curve radius (BCR) were compared in both groups. RESULTS: Patients with NV exhibited poorer best corrected visual acuity and more myopia than controls (p = 0.008 and 0.006, respectively). In univariate analysis, highly myopic patients (-9 diopters [D] or higher) were more likely to experience NV (odds ratio [OR], 2.232; 95% confidence interval [CI], 1.602 to 3.105). High astigmatism (> or =2 D) increased the risk of complications (OR, 2.717; 95% CI, 1.141 to 6.451). Steep cornea, in which BCR was <7.5 mm, also raised the risk of complications (OR, 4.000; 95% CI, 1.661 to 9.804). Flat cornea was not a risk factor for the development of NV. CONCLUSIONS: High myopia, high astigmatism, and steep cornea seemed to be risk factors in the development of corneal NV in SCL wearers.
Adult ; Astigmatism/diagnosis ; Biometry ; Case-Control Studies ; Contact Lenses, Hydrophilic/*adverse effects ; Corneal Neovascularization/diagnosis/*etiology ; Female ; Humans ; Hydrogel ; Male ; Myopia/diagnosis/*therapy ; Prosthesis Fitting ; Retrospective Studies ; Risk Factors ; Visual Acuity

We studied the influence of electrode array parameters on temperature distribution to the retina during the use of retinal prosthesis in order to avoid thermal damage to retina caused by long-term electrical stimulation. Based on real epiretinal prosthesis, a three-dimensional model of electrical stimulation for retina with 4 X 4 microelectrode array had been established using the finite element software (COMSOL Multiphysics). The steady-state temperature field of electrical stimulation of the retina was calculated, and the effects of the electrode parameters such as the distance between the electrode contacts, the materials and area of the electrode contact on temperature field were considered. The maximum increase in the retina steady temperature was about 0. 004 degrees C with practical stimulation current. When the distance between the electrode contacts was changed from 130 microm to 520 microm, the temperature was reduced by about 0.006 microC. When the contact radius was doubled from 130 microm to 260 microm, the temperature decrease was about 0.005 degrees C. It was shown that there were little temperature changes in the retina with a 4 x 4 epiretinal microelectrode array, reflecting the safety of electrical stimulation. It was also shown that the maximum temperature in the retina decreased with increasing the distance between the electrode contacts, as well as increasing the area of electrode contact. However, the change of the maximum temperature was very small when the distance became larger than the diameter of electrode contact. There was no significant difference in the effects of temperature increase among the different electrode materials. Rational selection of the distance between the electrode contacts and their area in electrode design can reduce the temperature rise induced by electrical stimulation.
Electric Stimulation ; Finite Element Analysis ; Microelectrodes ; Models, Theoretical ; Retina ; physiology ; Software ; Temperature ; Visual Prosthesis

Boosting spatial resolution of visual prostheses is an effective method to improve implant subjects' visual perception. However, power consumption of visual implants greatly rises with the increasing number of implanted electrodes. In respond to this trend, visual prostheses need to develop high-efficiency wireless power transmission and high-speed data transmission. This paper presents a review of current research progress on wireless power and data transmission for visual prostheses, analyzes relative principles and requirement, and introduces design methods of power and data transmission.
Electric Power Supplies ; Prosthesis Design ; Visual Prosthesis ; Wireless Technology