View clinical trials related to Vision.
Filter by:The aim of this study is to collect data on the early visual development of extreme premature infants. The method is the measurement of flash visual evoked potentials and the study population includes premature infants under the 28th weeks of gestation, who have normal cranial ultrasound examinations, normal aEEG, no clinical neurological symptoms and who have a normal ophthalmological status. fVEP measurements were recorded from the first week of life every second week until term. The fVEP recordings were performed in active sleep, in stable premature infants, who were continuously monitored. The Nihon Kohden Neuropack 8 was used, the stimulus frequency was 0,5 Hz, artefact free averages were analyzed. The measurements were analyzed according to the presence and absence of known waveforms, their latencies and amplitudes. Longitudinal analysis was performed to analyse the effect of extrauterine visual development on fVEP with growing gestational ages.
Measure wettability of hydrogel and silicone hydrogel contact lenses presoaked in a Multi-Purpose Solution.
The study design is a randomized intervention evaluation. Ten senior centers in predominately African American communities in the Birmingham, Alabama will be selected as sites for the educational intervention. Five centers will be randomly assigned to receive an educational intervention communicating practical information about vision, eye conditions and eye care as pertinent to the older African American population. The other five centers will serve as social-contact controls, where participants will receive an engaging information session on a non-health related topic. The primary outcome of interest is the change in percentage of persons receiving comprehensive eye care from pre- to post- intervention. The secondary outcomes are the process outcomes of improvement in knowledge, attitudes, and values about vision, eye conditions, and eye care.
In blind individuals, the occipital cortex becomes capable of processing tactile and auditory information, a phenomenon described as crossmodal plasticity. GABA is the major inhibitory neurotransmitter in the brain and a possible candidate to mediate this form of human plasticity. We intend to use magnetic resonance spectroscopy (MRS) to measure GABA and hypothesize that GABA levels in the occipital cortex of blind humans will be lower than in sighted controls. Such decrease could possibly mediate compensatory changes in the occipital cortex of the blind. Objective Early blind subjects exhibit better tactile acuity than late blinds or sighted individuals. The purpose of the study is the determine GABA levels in the human occipital cortex after long-term light deprivation (blindness). Study Population Our experiments will make use of early blind, late blind, and sighted control subjects. Design Subject will be identified and will receive clinical and neurological examinations at the NIH. MRS studies will be performed at NIH MRI Center with 3Tesla Magnet. Each subject head will be positioned in an adjustable holder (designed for minimal motion and maximal comfort) such that a flat coil lay just below the occipital cortex. The sequence has been described before [33]. The individuals who perform the data analysis will be blind to the purpose of the experiments. Outcome measures The concentration of GABA from the 14 ml voxel over the visual cortex will be measured. Edited proton spectrum of GABA will be compared with the edited sub spectrum of creatine for a concentration reference.