Search results for "Optometry"
showing 10 items of 812 documents
Efficacy and safety study of an eyelid gel after repeated nocturnal application in healthy contact lens users and non-users
2020
Purpose: To evaluate skin biocompatibility of a nighttime hydrating eyelid gel and possible ocular surface effects in contact lens users (CLU) and non-contact lens users (NCLU). The formulation is registered as a medical device as Tridocosahexaenoine-AOX® (TDHA-AOX) (a concentrated DHA triglyceride), containing also hyaluronic acid (HA). Methods: A prospective, randomized, masked clinical trial was performed with 62 participants of both sexes, aged 20–70 years, split into: (1) CLU (n = 30) and (2) NCLU (n = 32). All participants were instructed to apply a single dose of the moisturizing gel (containing TDHA-AOX and HA) nightly to the upper and inner eyelids of their right eye (RE) only, and…
Color and photography in the restorative dentistry. A brief communication about color temperature, dental color and the use of light and photography …
2020
Relevance. Optical properties of dental tissues can be captured by photography, considering the characteristics of the light sources. Therefore photography might become a way to communicate the color and the characterizing aspects of the teeth, reducing the misunderstandings between the dental practice and the laboratory in the project of dental restoration. Purpose. To illustrate some ways of using the current photographic technology to document teeth color correctly, and to be able to communicate it without misunderstandings and to replicate it in a simple way. Materials and methods. The photographs were taken using Nikon D500 digital camera, Nikkor 60 mm 2.8 macro lens, Nikon SB-700 Spee…
Quantitative corneal anatomy: evaluation of the effect of diabetes duration on the endothelial cell density and corneal thickness.
2014
Purpose To evaluate the differences in endothelial cell density (ECD) and central corneal thickness (CCT) between type II diabetic patients and age-matched healthy controls, and determine the impact of time from diagnosis. Methods This is a comparative study of 77 eyes of type II diabetic patients (33 males, 44 females) and 80 eyes of healthy subjects (42 males, and 38 females) whose ages ranged from 38 to 56 years. CCT, ECD, HbA1c levels, and Goldmann tonometry were measured. Results The CCT was significantly higher and the ECD significantly lower in long-term diabetic patients (10 years + since diagnosis) when compared with short-term diabetic patients (<1 year since diagnosis) and contro…
Axial Length and Anterior Segment Alterations in Former Preterm Infants and Full-Term Neonates Analyzed With Scheimpflug Imaging.
2017
Purpose To compare the axial length and anterior segment alterations in preterm infants with and without retinopathy of prematurity with those of full-term infants. Methods The Wiesbaden Prematurity Study investigated 503 participants of former gestational age ≤32 weeks and gestational age ≥37 weeks now being aged 4 to 10 years. This study included 485 participants in the prospective controlled cross-sectional, hospital-based study with successful Pentacam Scheimpflug imaging. Anterior segment parameters, axial length measurements, and associated factors were analyzed. Results Corneal thickness did not differ between former preterm and full-term infants. Significant differences were found b…
Fractal-structured multifocal intraocular lens
2017
[EN] In this work, we present a new concept of IOL design inspired by the demonstrated properties of reduced chromatic aberration and extended depth of focus of Fractal zone plates. A detailed description of a proof of concept IOL is provided. The result was numerically characterized, and fabricated by lathe turning. The prototype was tested in vitro using dedicated optical system and software. The theoretical Point Spread Function along the optical axis, computed for several wavelengths, showed that for each wavelength, the IOL produces two main foci surrounded by numerous secondary foci that partially overlap each other for different wavelengths. The result is that both, the near focus an…
Accommodation in human eye models: a comparison between the optical designs of Navarro, Arizona and Liou-Brennan.
2017
Aim To simulate and compare accommodation in accommodative and non-accommodative human eye models. Methods Ray tracing and optical design program was used. Three eye models were designed and studied: the Navarro, the Arizona and the Liou-Brennan. In order to make the Navarro and Liou-Brennan models to accommodate, specific geometric parameters of the models were altered with values that were chosen from the literature. For the Arizona model, its' mathematical functions for accommodation were used for the same accommodative demands. The simulation included four distances of accommodation for each model: at infinity, 3, 1 and 0.5 m.The results were diffraction images of a "letter F" for graph…
Syndrome de la fissure orbitaire supérieure post-traumatique : mise au point
2016
The traumatic superior orbital fissure syndrome is an uncommon complication of craniomaxillofacial trauma. The diagnosis is clinical and associates ophtalmoplegia (constantly at initial clinical examination), ptosis and anaesthesia of the forehead. Young men victim of road traffic accidents are most often affected. CT-scan usually shows facial and/or craniofacial fractures more or less spreading towards the superior orbital fissure. The absence of fracture seen at the X-rays does not eliminate the diagnosis. Initial management should be multidisciplinary (maxillofacial surgeons, ophthalmologists and neurosurgeons) and conducted early if possible. It combines high-dose corticosteroids and de…
Objective assessment of the effect of pupil size upon the power distribution of multifocal contact lenses
2017
AIM: To analytically assess the effect of pupil size upon the refractive power distributions of different designs of multifocal contact lenses. METHODS: Two multifocal contact lenses of center-near design and one multifocal contact lens of center-distance design were used in this study. Their power profiles were measured using the NIMO TR1504 device (LAMBDA-X, Belgium). Based on their power profiles, the power distribution was assessed as a function of pupil size. For the high addition lenses, the resulting refractive power as a function of viewing distance (far, intermediate, and near) and pupil size was also analyzed. RESULTS: The power distribution of the lenses was affected by pupil siz…
Stability of tacrolimus ophthalmic solution
2017
Purpose The stability of 0.3-mg/mL tacrolimus ophthalmic solution at different storage temperatures was studied. Methods A sterile ophthalmic solution of 0.3 mg/mL tacrolimus was prepared in triplicate under aseptic conditions by diluting tacrolimus in eye drops. Three aliquots of this solution were transferred into polypropylene bottles and stored at 25, 2–8, or −15 to −25 °C. Samples were collected immediately after preparation and at selected time points and assayed in triplicate using high-performance liquid chromatography (HPLC). Samples were also visually examined for macroscopic changes. The 0.3-mg/mL tacrolimus solution was also exposed to acidic treatment and heat to force its degr…
Discrimination of astringent and deastringed hard ‘Rojo Brillante’ persimmon fruit using a sensory threshold by means of hyperspectral imaging
2019
[EN] Persimmon fruit cv. 'Rojo Brillante' is an astringent cultivar due to its content of soluble tannins, which are insolubilised during the ripening of the fruit. Traditionally, the consumption of this cultivar has only been possible when the fruit is overripe and the texture is soft. Postharvest treatments based on exposing fruits to high CO2 concentrations allow astringency removal while preserving high flesh firmness. However, the effectiveness of this treatment is controlled by means of slow destructive methods. The aim of this work is to study the application of hyperspectral imaging in the spectral range 450-1040 nm to discriminate astringent (A) and deastringed (DA) fruits non-dest…