Active clinical trials for "Refractive Errors"

The purpose of this study is to evaluate the accuracy and repeatability of an individually validated prototype autorefractor designed to be mounted on a surgical microscope.

The studied patients will be given randomly one of three following drugs1:Gabapentin2: Pregabalin or placebo for 3 days after Photorefractive keratectomy surgery. The pain will be measured based on visual analog scale(VAS) on the day of operation and on the 3 rd day (morning, evening) and then compared among three groups.

To assess the improvement in myopia with phototherapeutic intrastromal corneal collagen cross-linking (PiXL) without epithelial debridement (epi-on) in high oxygen environment for low grade myopia. The study compares two 3.5-mm central ring-shaped zone protocols; 10 min illumination time vs 16:40 min illumination time.

The purpose of this study is to carry out an international multicenter trial to get more convincing and valuable results of the SMILE surgery and compare the outcomes between the SMILE surgery and the FS-LASIK (femtosecond laser assisted-laser in situ keratomileusis) surgery. The investigators hope to investigate the differences between the SMILE and the FS-LASIK surgery comprehensively, including the comparison of visual acuity, refraction, the correction of cylindrical diopter, the high order aberrations, the corneal biomechanics, the corneal ectasia, the characteristics of the changes of central corneal thickness and the complications. To meet the demands of a multi center trial, all the examination equipments should be same in each center, and this will limit the variations within a study

Axial hyperopia results when the length of the eye is too short for the eye to properly focus distance objects on the retina while the focusing system is relaxed. Emmetropization is the process by which the eye actively adjusts various components of the eye to gradually improve the focus of the eye. Emmetropization frequently involves either an increase or a decrease in the growth of the eye, particularly during infancy and childhood. Numerous animal studies suggest that if an animal is exposed to retinal images located behind the retina either centrally or peripherally, the eye will grow in the direction of the focused image. If an abnormally short eye has resulted in hyperopia, exposing such an eye to retinal images partially located behind the retina might encourage axial elongation, thus reducing the hyperopia.

Single-center, open-label, prospective study in healthy volunteers desiring refraction for correction of visual acuity to compare a handheld device supported by a mobile application with the phoropter and autorefractor.

The purpose of this study is to evaluate the performance of two commercially-available silicone hydrogel contact lenses in normal and low humidity environments after at least 7 days of wear.

The purpose of this study is to evaluate worn AIR OPTIX® plus HYDRAGLYDE® (AOHG) lenses cleaned and disinfected with HYDRAGLYDE® containing lens solutions compared to each of the control habitual silicone hydrogel (SiHy) lenses cleaned and disinfected with habitual multi-purpose solution (MPS) for cholesterol uptake.

Refractive surgery includes interventions to correct refractive errors, using a medical device such as a laser or an implant (intraocular lenses) or surgical instruments. The study distinguishes corneal interventions, carried on the surface of the eye, and intraocular interventions, performed on the lens or in the anterior or posterior chamber of the eye. The number of procedures in refractive surgery is growing significantly. They seem to offer satisfactory visual results but a number of issues remains unresolved. In order to get emmetropia, refractive surgery corrects optical defects by decreasing aberrations of lower orders (ie spherical refractive error and astigmatism). This increases high-order aberrations (the most common is a bright halo on the edge of the image). The cutting of the flap to the surface of the cornea in the case of LASIK increases high-order aberrations, which have the effect of reducing post-surgical visual performance (ie visual acuity and contrast sensitivity) and can't be corrected by glasses, while the adaptation of contact lenses on a post-operative cornea is more complex. It is therefore necessary to limit these post-surgical aberrations and to identify their possible sources. Indeed, some authors have provided insight into the effects of some high-order aberrations, but the influence of several factors characterizing the preoperative eye on refractive surgery are still unknown, such as pupillary diameter, depth of the anterior chamber, Intra Ocular Pressure or astigmatism.

The purpose of this study is to measure the coefficient of friction of three silicone hydrogel, daily disposable contact lenses after 16 hours of wear.