Search results for "Optometry"

Corneal Aberrations, Contrast Sensitivity, and Light Distortion in Orthokeratology Patients: 1-Year Results.

2016

Purpose. To evaluate the corneal higher-order aberrations (HOA), contrast sensitivity function (CSF), and light distortion (LD) in patients undergoing orthokeratology (OK). Methods. Twenty healthy subjects (mean age: 21.40 ± 8 years) with mean spherical equivalent refractive error M = −2.19 ± 0.97 D were evaluated at 1 day, 1 month, and 1 year after starting OK treatment. Monocular LD, photopic monocular CSF, and corneal HOA for 6 mm pupil size were measured. Results. LD showed an increase after the first night (𝑝 0.05). Spherical-like, coma-like, and secondary astigmatism HOA RMS increased significantly (𝑝 ≤ 0.022) from baseline to 1-month visit, remaining unchanged over the follow-up. C…

Outcome of Bleb Revision With Autologous Conjunctival Graft Alone or Combined With Donor Scleral Graft for Late-onset Bleb Leakage With Hypotony Afte…

2020

Prcis Treatment of leakage with ocular hypotony after trabeculectomy with mitomycin C (MMC) can be safely achieved through conjunctival patch alone or combined with donor scleral graft in cases of melted underlying sclera. Purpose To report outcomes of 2 surgical approaches for treating ocular hypotony in eyes with blebs with late-onset leakage after standard trabeculectomy with MMC. Methods Thirty consecutive cases with bleb leakage and hypotony underwent bleb revision surgery between 2009 and 2014 by the same surgeon (J.W.) at the Department of Ophthalmology of the Mainz University Medical Center, Germany. In 18 patients, an autologous conjunctival patch graft was applied. In 12 patients,…

Images perceived after chromatic or achromatic contrast sensitivity losses.

2010

Purpose. We simulate how subjects with losses in chromatic and achromatic contrast sensitivity perceive colored images by using the spatiochromatic corresponding pair algorithm. Methods. This is a generalized version of the algorithm by Capilla et al. (J Opt Soc Am (A) 2004;21:176 –186) for simulating color perception of color deviant subjects, which incorporates a simple spatial vision model, consisting of a linear filtering stage, with a band-pass achromatic filter and two low-pass chromatic ones, for the red-green and blue-yellow mechanisms. These filters, except for the global scaling, are the subject’s contrast sensitivity functions measured along the cardinal directions of the color s…

Enrichment of Retinal Ganglion Cells in Rat Retinal Lysate by Excimer Laser Ablation of the Outer Retina

2013

PURPOSE. Retinal ganglion cells (RGC) are a relatively small cell population in the retina. This leads to an unfavorable signal-tonoise ratio when analyzing RGC proteins in whole retina lysate. We present a novel technique to obtain RGC-enriched rat retinal lysate by removing the outer retinal layers with an excimer laser before lysation. METHODS. Outer retinal layers were ablated with an excimer laser on flat mounted retinas from adult albino rats. 4 0 6Diamidino-2-phenylindole dihydrochloride hydrate (DAPI) nuclear staining was used to assess the ablation efficacy (n ! 6). Western blot for layer specific markers (rhodopsin, parvalbumin, b-III-tubulin) was performed to quantify changes in …

Short-Time Ocular Ischemia Induces Vascular Endothelial Dysfunction and Ganglion Cell Loss in the Pig Retina

2019

Visual impairment and blindness are often caused by retinal ischemia-reperfusion (I/R) injury. We aimed to characterize a new model of I/R in pigs, in which the intraocular pathways were not manipulated by invasive methods on the ocular system. After 12 min of ischemia followed by 20 h of reperfusion, reactivity of retinal arterioles was measured in vitro by video microscopy. Dihydroethidium (DHE) staining, qPCR, immunohistochemistry, quantification of neurons in the retinal ganglion cell layer, and histological examination was performed. Retinal arterioles of I/R-treated pigs displayed marked attenuation in response to the endothelium-dependent vasodilator, bradykinin, compared to sham-tre…

2017

Background Patients with retinal vascular occlusion disease have an increased risk for ischemic stroke and share some risk factors with cerebrovascular disease. The purpose of this study was to analyze the prevalence of atrial fibrillation (AF) in subjects with retinal vascular occlusive disease and anterior ischemic optic neuropathy and to compare these data to an ischemic stroke group. Methods Prospective, observational single-center trial. Subjects with retinal artery occlusion (RAO), retinal vein occlusion (RVO) and anterior ischemic optic neuropathy (AION) were included. Patients with ischemic stroke (IS) from a previous observational trial were used as control. Investigation included …

2013

Background To monitor viability of implanted genetically engineered and microencapsulated human stem cells (MicroBeads) in the mouse eye, and to study the impact of the beads and/or xenogenic cells on retinal integrity. Methodology/Principal Findings MicroBeads were implanted into the subretinal space of SV126 wild type mice using an ab externo approach. Viability of microencapsulated cells was monitored by noninvasive retinal imaging (Spectralis™ HRA+OCT). Retinal integrity was also assessed with retinal imaging and upon the end of the study by light and electron microscopy. The implanted GFP-marked cells encapsulated in subretinal MicroBeads remained viable over a period of up to 4 months…

A novel automated segmentation method for retinal layers in OCT images proves retinal degeneration after optic neuritis.

2015

Aim The evaluation of inner retinal layer thickness can serve as a direct biomarker for monitoring the course of inflammatory diseases of the central nervous system such as multiple sclerosis (MS). Using optical coherence tomography (OCT), thinning of the retinal nerve fibre layer and changes in deeper retinal layers have been observed in patients with MS. Here, we first compare a novel method for automated segmentation of OCT images with manual segmentation using two cohorts of patients with MS. Using this method, we also aimed to reproduce previous findings showing retinal degeneration following optic neuritis (ON) in MS. Methods Based on a 5×5 expansion of the Prewitt operator to efficie…

Production of a Double-Layer Scaffold for the “On-Demand” Release of Fibroblast-like Limbal Stem Cells

2019

The production and characterization of a double layer scaffold, to be used as a system for the “on demand” release of corneal limbal stem cells are here reported. The devices used in the clinics and proposed so far in the scientific literature, for the release of corneal stem cells in the treatment of limbal stem cell deficiency, cannot control the in vivo space-time release of cells since the biomaterial of which they are composed is devoid of stimuli responsiveness features. Our approach was to produce a scaffold composed of two different polymeric layers that give the device the appropriate mechanical properties to be placed on the ocular surface and the possibility of releasing the stem…

User Evaluation of the Smartphone Screen Reader VoiceOver with Visually Disabled Participants

2018

Touchscreen assistive technology is designed to support speech interaction between visually disabled people and mobile devices, allowing hand gestures to interact with a touch user interface. In a global perspective, the World Health Organisation estimates that around 285 million people are visually disabled with 2/3 of them over 50 years old. This paper presents the user evaluation of VoiceOver, a built-in screen reader in Apple Inc. products, with a detailed analysis of the gesture interaction, familiarity and training by visually disabled users and the system response. Six participants with prescribed visual disability took part in the tests in a usability laboratory under controlled con…