View clinical trials related to Visual Acuity.
Filter by:This study will test the feasibility that differences in contact lens wettability can be measured with a wavefront sensor.
The purpose of this study is to evaluate the etafilcon - PVP (multi-focal)
To evaluate the impact of a new contact lens hydration process
To analyze macula edema formation after cataract surgery called Irvine-Gass-Syndrome.
Human visual acuity and contrast sensitivity are highly dependent on various different parameters. Each should be optimized for perfect visual performance. However, in real life our eyes lack such parameters, which might lead to unsatisfying results even after spectacle correction or contact lenses. A promising approach would be to design intra ocular lenses (IOL), which are implanted into the eye for example in the course of cataract extraction and are able to compensate for the human eyes' aberrations. For example cutoff frequency, edge-sharpness or specific contrast for selected structure sizes would need to be considered. Since, an aberration free optical system is almost impossible and since the impact of each single parameter is not yet known, IOL design parameters would have to be chosen very carefully. Furthermore, image quality of IOLs still is tested ex vivo by ray tracing for example, but this does not guarantee perfect function after implantation, as our visual system has complex image precessing units form the retina to the brain. The present study picks one of these parameters and seeks to assess its impact on visual quality in-vivo. By subjectively grading different images with objective changes to image quality by variations of the modulation transfer function (MTF), the potential influence and thus on our subjective visual impression shall be assessed.
Age related cataracts are responsible for about 51 percent of blindness worldwide and according to the WHO affect about 20 million people, according to the WH . As cataract surgery is firstline treatment in the western world, there is a constant attempt to improve artificial intraocular lenes (IOL). As for this study, the investigators seek to compare four different IOL designs in in a psychophysiological setting, allowing to assess the impact of these IOLs on vision and psychological processing of visual information. As these IOLs also have downsides, such as reduced light intensity or image alterations, the subjective preference and overall impression shall be investigated. The healthy subjects look through a stable spectacle frame mounted onto a table, which enables the investigator to insert the different IOLs. This would allow subjective testing of IOLs before surgery.
Purpose: To investigate the relationship between retinal thickness (RT) and metabolic risks (MRs) in patients without retinal lesion. Methods: Fifty-two patients over 60 y/o were divided into four groups according to their MRs of hypertension, hyperlipidemia or hyperglyceremia. After complete ophthalmic examination, optical coherence tomography was performed to measure RT.
The purpose of this study is to evaluate visual acuity in different lighting conditions (daylight and night time) and distances (distance, near and intermediate), and the independence of glasses, in patients who have had binocular implantation of the Tecnis Multifocal IOL or the Crystalens™ HD Accommodating IOL.
The purpose of this study is to compare functional and anatomical results of a combined surgery and two time surgery for macular hole and cataract extraction in one hundred and twenty patients (120 eyes) with idiopathic Macular Hole (MH) and cataract in two academic centers.
ZK 200775 is an antagonist at the α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor and had earned attention a possible neuroprotective agent in cerebral ischemia. Probands receiving the agent within a stroke therapy related Phase I trial reported on an alteration of visual perception. In this trial, the effects of ZK 200775 on the visual system will be analyzed in detail. In a randomised, placebo-controlled, double-blind study eyes and vision will be examined before and after the intravenous administration of ZK 200775. The following methods will be applied: clinical examination, visual acuity, ophthalmoscopy, colour vision, rod absolute threshold, central visual field, pattern-reversal visual evoked potentials (pVEP), ON-OFF and full-field electroretinogram (ERG).