Active clinical trials for "Refractive Errors"

To determine the longitudinal changes of age and refraction in predicting myopia progression with risk under the coronavirus disease 2019 (COVID-19) pandemic in a 3-year follow-up of a Chinese cohort.

Aberrations play a significant role in the visual process and can be divided in lower-order and higher-order aberrations. The former can be measured using the commercially available IOL Master (Carl Zeiss Meditec AG, Germany) and have profound influence on visual acuity. Higher-order aberrations do not significantly influence visual acuity but affect the quality of vision and can cause halos, double vision, and night vision disturbances. Background Cataract surgery has become a routine procedure in the developed countries. During this surgery, a foldable intraocular lens is usually inserted into the capsular bag. However, these lenses do not account for individual optical biometry data or aberrations. Therefore, it is important to provide data for ametropic and emmetropic eyes as this information might improve future intraocular lens design and lead to individually adapted lenses for yielding optimal visual acuity and quality results. The aim of the present study is to clarify the correlation between refractive errors/axial eye length and spherical aberrations of the cornea.

Youth and some adults have photoscreening refractions and hand-held auto refraction before cycloplegia refraction during new and follow up eye examinations. Vector math is applied to each refraction to determine how closely the hand-held "dry" devices match actual refraction.

This project involves evaluation of post operative contrast sensitivity and wavefront aberration results among patients implanted with standard monofocal lenses (Acrysof SN60AT/SN60WF) and the new presbyopic correcting multifocal lens (Acrysof ReSTOR). Higher Order aberrations are visual phenomena such as glare and haloes. They are more prevalent after cataract surgery and can affect night driving.

Prospective, multi-center, non-interventional, randomized, comparative clinical study to identify an optimal refractive technique that provides maximum plus refractive endpoint for best corrected distance visual acuity (BCDVA).

The present research process is a prospective clinical study that will be conducted under the auspices of the Democritus University of Thrace (DUTH) in the open accommodation structure for refugees and immigrants of Kavala, Kavala, Greece, and the Pre-Removal Detention Center (PROKEKA) for Foreigners of Kos, Kos, Greece. The study aims to assess the basic ophthalmological condition of the refugee/immigrant population and is developed in two main areas: The recording of the ophthalmological care that the refugee/immigrant has received until his/her inclusion in the study through a structured questionnaire (eg previous examinations, spectacle utilization, pharmaceutical or other interventions, etc.) The measurement of monocular best-spectacle corrected visual acuity in both eyes using a web-based visual acuity chart. Adult participants living in the two aforementioned centers will be recruited in a consecutive-if-eligible basis. All age groups will be proportionally represented (proportional age distribution).

The objective of the current study is to prospectively evaluate 3-month clinical outcomes from LASIK performed using the Phorcides surgical planning software with Contoura topography-guided ablation in both eyes of subjects with myopia and myopic astigmatism seeking refractive surgery for distance correction.

This Study determines the most precise method for measuring post-operative refraction following implantation of the asymmetric multifocal LS-313 MF30 comparing the results of Refraction of the different Autorefractor Keratometers with the subjective measurements for distance and near.

The purpose of this study is to determine whether tropicamide + phenylephrine cyclopentolate + applied for once waiting 30 minutes to retinoscopy (new scheme) is not inferior to apply cyclopentolate alone and wait 45 minutes to retinoscopy (traditional scheme)

This study will provide a profile of blindness/visual impairment, avoidable blindness and cataract surgery service in Chaonan, mainland China. We also evaluate the diagnostic accuracy of Rapid Assessment of Avoidable Blindness (RAAB) comparison with conventional survey.