Visual Acuity

This study seeks to determine whether glasses prescriptions determined from computer analysis of detailed images of the eyes provide better vision outcomes for children with Down syndrome than prescriptions determined using routine clinical methods.

The goal of this randomized, double-blind clinical trial is to determine whether transcranial direct current stimulation (tDCS) can effectively and safely improve vision in children aged 4-14 years with strabismic or anisometropic amblyopia that has not responded to conventional patching therapy. The main questions it aims to answer are: Does tDCS produce significant and sustained improvements in visual acuity, contrast sensitivity, and stereopsis in children with amblyopia? Is tDCS a safe, well-tolerated, and faster alternative or complementary treatment compared with standard occlusion therapy? Does tDCS induce functional and structural changes in the visual cortex associated with increased neuroplasticity, including modulation of GABAergic activity? If there is a comparison group: Researchers will compare active tDCS with sham (placebo) stimulation to see if active treatment leads to greater visual recovery and cortical changes than placebo. Participants will: Receive several sessions of active or sham tDCS using low-intensity electrical stimulation applied to visual brain areas. Undergo standard visual assessments, including visual acuity, contrast sensitivity, and stereopsis. Complete neurophysiological and neuroimaging evaluations (EEG, pattern visual evoked potentials, and functional MRI). Provide biochemical measures related to GABA levels. This study aims to validate tDCS as a non-invasive, child-friendly, and effective therapy that may overcome the limitations of patching and support its inclusion in paediatric clinical practice.

The goal of this clinical investigation is to evaluate visual acuity and contrast sensitivity in low lighting conditions using several different testing devices, and measure nighttime side effects of intraocular lens (IOL) implants after cataract surgery. Researchers will compare the results for three different types of IOLs to see how each lens contributes to overall visual function, patient experience and satisfaction. Participants will: * Complete two different questionnaires about their current vision * Undergo visual testing using several different devices

The main objective of this clinical trial is to identify a variation in visual strategy characterized by both head movements and eye movements of healthy volunteers during a target detection task when images simulating night vision goggles (NVG) are presented, compared to a situation in which the images simulate a natural environment. To highlight changes in environmental scanning with simulated images from NVG, objective measurements will be collected: * eye movements characterized by saccades (speed, latency, and number) for each stimulus * head movements (horizontal angle of the participant's head) for each stimulus and throughout the exposure Participants sit facing a screen (9.90 m x 2.10 m) onto which a virtual scene is projected. The objective is to correctly identify, as quickly as possible, a target stimulus (represented by a tank) that may appear in the scene. They must use the directional arrows on a game controller to indicate whether the tank is moving to the left or to the right. There are four visits involving four viewing conditions in which the task remains the same: * With restricted field of view and a normal scene. * Without restricted field of view and a scene simulating the vision obtained by NVGs. * With restricted field of view and a scene simulating the vision obtained by NVGs. * Without restricted field of view and a normal scene. Regarding the content of the scene, half of the tests in each visit involve a so-called poor scene when fog is simulated, or an enriched scene when there is no fog. Each visit lasts approximately one hour and thirty minutes.

This prospective, observational investigation seeks to delineate the interplay between chromatic vision deficits and both functional visual outcomes and anatomical retinal biomarkers in individuals affected by Inherited Retinal Dystrophies (IRDs). The study will recruit approximately 200 subjects, encompassing a heterogeneous population of IRD patients-spanning a range of genotypes and clinical severities-as well as control participants devoid of retinal pathology. All enrolled individuals will undergo a standardized battery of evaluations, including quantitative color vision assessment, best-corrected visual acuity (BCVA) determination, and advanced multimodal retinal imaging. The principal aim is to characterize the relationship between impairments in color discrimination and morphologic disruptions within the outer retinal layers, with particular emphasis on the continuity and reflectivity of the ellipsoid zone (EZ)-historically referred to as the inner segment/outer segment (IS/OS) junction-assessed through spectral-domain optical coherence tomography (SD-OCT). Further, the study will explore associations between chromatic perceptual deficits and underlying genetic mutations, mutation patterns specific to IRD subtypes, and the influence of patient age on the severity and progression of color vision loss. A key secondary objective is the clinical appraisal and validation of a novel diagnostic modality, the Moji Low-Vision Color Discrimination Test (Moji Test), which is specifically engineered to quantify residual color perception in individuals with advanced central visual impairment. The test's discriminatory capacity will be benchmarked against established color vision testing paradigms to assess its reliability, clinical sensitivity, and suitability for implementation in populations with severe visual acuity reduction. By incorporating a genetically and phenotypically diverse IRD cohort, the study is designed to enable granular, stratified analyses that will refine the understanding of structural-functional correlations in hereditary retinal disease. The inclusion of a control group with preserved retinal architecture and normal color vision function will provide essential normative baselines for comparative evaluation and statistical inference.

The goal of this observational methodological study is to validate the Turkish version of the DDIVAT visual acuity measuring device in a Turkish-speaking adult population. The main questions it aims to answer are: Does the Turkish version of the DDIVAT provide reliable and valid visual acuity measurements in Turkish speakers? Are the results of the DDIVAT comparable to those obtained with the standard Snellen chart used in clinical practice? Researchers will compare DDIVAT visual acuity test results with Snellen chart results to see if both methods produce consistent measurements. Participants will: Be adults aged 18 years or older, including both patients and healthy volunteers. Undergo visual acuity testing using the DDIVAT system displayed on a smart TV connected to the university server. Have their visual acuity re-measured using the standard Snellen optotype under the same conditions. No medication or invasive procedure will be used. The study carries no risk to participants.

The purpose of this research is to validate and determine the accuracy of the experimental device when measuring visual acuity versus our standard visual acuity measurements and to gather voice recordings of letters to help build a special system that recognizes spoken letters.

The ICOPE Brazil study aims to understand aging trajectories in Brazil, especially healthy aging trends based on intrinsic capacity, a collective of mental and physical capacities one may have to maintain their functional ability to execute daily life activities. Tests and questionnaires will be applied to collect data on mobility capacity, cognitive capacity, nutritional status, vision, and hearing (sensorial) capacities, and mental health. These assessments are in consonance with what the World Health Organization proposed in the Integrated Care for Older People Program (ICOPE). Participants will be followed up for three years, and the primary outcomes of interest are loss of intrinsic capacity, mobility impairment, cognitive impairment, incident depressive symptoms, loss of functional ability, incident frailty, incident sarcopenia, incident falls, hospitalization, multimorbidity, and mortality.

The goal of this clinical trial is to learn if oral melatonin can enhance visual acuity and central macular thickness in central serous chorioretinopathy (CSCR) in adults. The main questions it aims to answer are: 1. How does melatonin affect central macula thickness in CSCR? 2. How does melatonin affect visual acuity in CSCR? Researchers will compare placebo (a look-like substance that contains no drug) to see if melatonin works to treat CSCR. Participants will: 1. Take melatonin or placebo twice a day for one month 2. Visit the clinic after finishing a course of treatment, and 1 and 3 months after that for visual acuity assessment and tests 3. Keep a diary of their symptoms