View clinical trials related to Astigmatism.
Filter by:The purpose of this study is demonstrate substantial equivalence of an investigational contact lens disinfecting solution to a commercially available contact lens solution in silicone hydrogel and soft contact lens wearers.
The primary goal of the study is to determine if Optical Coherence Tomography (OCT) measurement of corneal power and astigmatism is more accurate than conventional Placido-ring corneal topography. A second goal is to evaluate OCT-based epithelial thickness mapping. The postoperative epithelial thickness variation will be used to calculate refractive effects and calibrate the smoothing parameter in the mathematical model relating corneal mean curvature and epithelial thickness. A third goal is to assess the repeatability of OCT measurements. A fourth goal is to develop a method of estimating the focusing power, astigmatism, and HOA of the crystalline lens based on measurements of the lens' anterior and posterior capsular topographies and positions with the ultrahigh-speed MIT OCT prototype.
The objectives of this study are to evaluate the safety and efficacy, with regards to regression of refractive outcome, as measured by manifest refraction spherical equivalent (MRSE), of two treatment regimens for hyperopic and hyperopic astigmatic subjects: LASIK followed by cross-linking performed with the KXL System and Photrexa ZD™ (Riboflavin Ophthalmic Solution), as compared to LASIK alone.
This clinical phase IV study is an open, prospective phase IV study and acts to evaluate the effectiveness of the femtolaser-assisted astigmatic keratotomy.
The purpose of this study is to compare the amount of coma as measured by aberrometry induced by two silicone hydrogel toric lenses in astigmatic participants.
The purpose of this study is to determine the benefits of fitting low astigmats with soft toric contact lenses versus spherical contact lenses with regard to visual comfort, eyestrain, fitting efficiency, and visual performance.
The investigational enVista IOL, Model MX60Tis equipped with toric optics and axis marks on the posterior surface to minimize the possibility of surgically induced astigmatism.
The purpose of this study was to compare lens comfort on Day 30 for Air Optix® lenses cared for with OPTI-FREE® PureMoist® (OFPM) Multi Purpose Disinfecting Solution (MPDS) compared to Acuvue® Oasys® lenses cared for with habitual MPDS.
One of the most recent advances in cataract surgery is microincisional phacoemulsification (MICS). Through small incisions of 2.0 mm and less the lens material is emulsified either bimanually or with a thin single coaxial hand-piece. The possible advantages are lower induced corneal astigmatism1, 2, possibly a lower incidence of infection due to higher resistance of the wound to deformation3 and a lower risk of complications such as iris prolapse during surgery in patients at risk such as with intraoperative floppy iris syndrome (IFIS). Additional factors that have to be taken into account are the construction and the position of the incision and the influence of the extraocular force on the wound morphology.4 Another effect that may influence the wound architecture is stromal hydration at the end of surgery.5 Wound architecture has recently been assessed6-9 using optical coherence tomography. Elkady et al.10 observed the wound architecture in MICS cases focusing on corneal thickness and the incision angle. However, none of these studies observed the effect of the wound architecture on post-operative astigmatism. Furthermore, all observations in the past have been performed in the post-operative period only and information concerning the wound architecture intra-operatively is missing. A recently launched CE-marked intra-operative OCT allows observing the wound architecture intra-operatively. One aim of the study is to assess the influence of the intra-operative wound architecture using a similar grading system as used by Calladine and Packard (2007)7 on the resistance to deformation of the wound and the surgically induced astigmatism in MICS and small incision cataract surgery (SICS). In a second part of this exploratory study the effect of a hinged incision with a pre-cut should be assessed along the same line
With increasing demands of patients concerning refractive outcome after cataract surgery, toric intraocular lenses (IOLs) that correct corneal astigmatism have been introduced more widely to cataract surgery. Originally toric IOLs were used mainly for patients with high degrees of astigmatism, especially after corneal surgical procedures such as penetrating keratoplasty. Since a couple of years, toric IOLs are available from numerous manufacturers to correct lower amounts of astigmatism which are much more prevalent with about 30% having a corneal astigmatism of 0.75D or more in the cataract population. This should result in less spectacle dependence of patients due to the astigmatic correction. The alternative method to reduce corneal astigmatism as part of cataract surgery is to make incisions on the steeper axis of the cornea such as limbal relaxing incisions or an additional clear corneal incision opposite (OCCI) to the main cataract opening. These techniques are in use since more than 2 decades and are widely used in clinical routine. As with toric IOLs, precise alignment of the cuts with the axis of astigmatism is essential. The disadvantage of the incisional techniques is the variability of the effect between patients since it depends on factors such as the extent of scaring of the cuts after surgery as well as corneal thickness. The main advantage is the simplicity of the technique and the lower cost. Aim of this study is to compare toric IOL implantation and opposite clear corneal incision during cataract surgery to correct corneal astigmatism.