View clinical trials related to Refractive Errors.
Filter by:This study aims to determine if Total30 lenses for astigmatism can be successfully fit in participants who are heavy digital device users.
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.
This is a unilateral, non-interventional study. Each subject will be unilaterally measured with the WAM-5500 autorefractor by 3 testers. All measurements will be made on the right eye only.
Refractive errors and corneal astigmatism are associated with changes in angle kappa and corneal back elevation at the thinnest point in Pentacam. The purpose of this study is to track: The effect of anterior corneal astigmatism treatment on angle kappa and corneal back elevation.
The purpose of this study is to assess the clinical performance of TOTAL30 for Astigmatism (T30fA) soft contact lenses with Biofinity Toric soft contact lenses.
Anxiety is common among patients undergoing eye surgery, which is typically performed under topical anesthesia while the patient is awake. This can be an unsettling experience for patients, who may worry about being able to keep their eyes still during surgery, cooperate with the surgical team, and remain immobile in an unfamiliar environment. Patients may also experience anxiety due to concerns about surgical pain, possible complications, and the uncertainty of the outcome of the surgery. In this study, the investigators aimed to investigate the correlation between the severity of anxiety symptoms during LASIK, and fixation instability during photo-ablation as plotted by the eye tracker.
Approximately 30 soft toric contact lens adapted subjects will be enrolled in this feasibility, bilateral, randomized, double masked (subject and investigator masked), repeated measures insertion study. All subjects will be seen for a Screening/Dispensing Visit at which informed consent will be obtained and eligibility will be assessed. If subjects satisfy all eligibility criteria and none of the exclusion criteria, subjects will have study lenses inserted in random, successive order according to unique randomization schedules that will be provided to each Investigator.
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.