View clinical trials related to Refractive Errors.
Filter by:The goal of this observational study is to test whether surgeries for lenses designed to be implanted in the eye to correct refractive error can be done without the need for using viscoelastic substances that are used routinely nowadays to make it easier to introduce them inside the human eye and protect the inside of the eye during the operation. The main question it aims to answer is that is it safe to do the surgery without using them? to answer this question researchers will access recorded data of patients that underwent refractive surgeries in a private clinic since 2017 and compare them as two groups: those who underwent the traditional procedures and those who had it without the use of dispersive viscoelastics in regard to their vision before and after surgery, their ocular pressure and biomicroscopic analysis of the inside of their corneas before and after surgery.
The primary objective of this study is to identify how many focal points and at which distances are necessary for reliable visual curve formation and area of the curve (AoC) calculation using mathematical models and comparing the results to measurements acquired from participants that underwent uncomplicated pseudophakic presbyopia surgery.
The primary outcome of this study is to compare cyclopentolate 1% and tropicamide 1% for cycloplegic refractions in pediatric populations with esotropia. This will be a prospective double-blinded randomized clinical trial (RCT), multi-center, with randomized sequencing of cycloplegic agent; each patient received one agent at one visit, and the other agent in the next visit (2 different visits ≥ 1 week apart) within 3 months.
The main objective of the Sierra Leone Sees to Learn (SL2) trial is to assess the educational impact of providing free eyeglasses to students aged 12-15 years with uncorrected refractive error in Sierra Leone. The procedures include baseline questionnaires and educational assessments to collect data on students and schools, and then the provision of free eyeglasses to students who have uncorrected (or undercorrected) refractive error (URE). The questionnaires and student assessments will take 1-2 hours. The duration of the study timeframe is one school year. The end-line questionnaires and student assessments will be administered at the end of the school year.
Small incision lenticule extraction (SMILE) is a refractive intrastromal procedure for myopia and myopic astigmatism correction. Most of the studies evaluating astigmatic correction by SMILE reported astigmatic under-correction, especially in high degrees of astigmatism. This under-correction could be due to: first, the active eye tracker or the iris registration is not yet available to overcome the cyclotorsion that occurred during the treatment with the VisuMax femtosecond laser system (Carl Zeiss Meditec, Jena, Germany) which could be overcome by manual compensation technique, especially in higher degrees of cylinders (> 1.5 diopters (D)). Second, in patients with small lenticule diameters, the more abrupt change in thickness at the edge of the treated area could induce more stromal and epithelial healing in this area. Thus, the astigmatic correction would be less effective with small than large lenticule diameters for similar high preoperative astigmatism. This study assessed the outcome of using a 0.5 millimeter (mm) larger lenticule diameter in the fellow eyes of myopic astigmatic correction SMILE participants. This assessment included the safety and effectiveness indices, the refractive and visual outcomes, the contrast sensitivity, and some morphological outcomes such as corneal curvature and epithelial and corneal thickness.
Determine if Total30 for Astigmatism contact lenses (CLs) provide a comfortable wearing experience all day. CL discomfort affects most CL wearers with discomfort consistently topping the reasons why established CL wearers drop out of CLs. In fact, studies have consistently found that the frequency of CL dropout is around 20% with this dropout frequency staying relatively stable over the past 20 plus years. This static frequency of CL dropout is surprising since there have been a number of dramatic soft CL innovations during this time frame (e.g., widely available daily disposable CLs, silicone hydrogel CL materials with high oxygen transmissibility, new CL surface coatings).
The purpose of this study is to assess the WaveLight Ultraviolet Femtosecond Laser System, Model 1026 (UV fs-Laser) corneal flap creation accuracy as compared to the already marketed WaveLight FS200 Infrared Femtosecond Laser, Model 1025 (IR fs-Laser).
Corrective eye surgeries, such as Lasik, are widely used to correct focusing problems such as myopia, or nearsightedness. Often these patients develop other conditions like myopic maculopathy or glaucoma which require monitoring with optical coherence tomography (OCT). Since OCT is a light-based test and changes the refractive status of the eye (in the cornea or the lens), it can potentially affect the results of the OCT measurements but has not been sufficiently studied. This pilot study aims at studying the potential change in OCT parameters in the eye after undergoing such surgery.
This is a 12-month longitudinal randomized controlled trial aiming to evaluate the effect of colour temperature of reading lamp on refractive error development.
The objective of this intervention study was to understand the visual health status of nearly one million children and adolescents in ten provinces in China, and then to conduct intervention and evaluate the effect of intervention measures with the development of myopia as the outcome indicator. The study will be conducted in the form of a stepped intervention and will answer the following questions. Current China children and adolescent's vision health, including the different degrees of myopia prevalence, and farsightedness reserve status. To evaluate the implementation and effect of eight appropriate technologies and six interventions developed in this study, to reduce the incidence of myopia among children and adolescents in China, to achieve the purpose of nationwide application. In the early stage of this study, a baseline survey will be conducted on participants. In the middle stage, participants will be required to adjust the seat height regularly and increase the time for outdoor activities, etc. In the later stage, intervention measures will be evaluated based on the overall research situation to consider national promotion.