Active clinical trials for "Astigmatism"

It is a common clinical practice to leave small amounts of astigmatism uncorrected in contact lens wearers. Therefore, some drivers who have astigmatism and wear contact lenses may experience blur while driving. The purpose of this study is to determine if correcting small amounts of astigmatism with contact lenses will improve driving safety.

The primary objective of this study is to evaluate the safety and effectiveness of performing 0.50 D cylinder correction on the RxSight Light Adjustable Lens (LAL) in patients who have undergone implantation with the FDA approved, commercially available LAL.

Brief Summary: Age-related cataract is the main cause of impaired vision in the elderly population worldwide. In the UK, more than half of people who are over 65 years old have some cataract development in one or both eyes. The only treatment that can restore functional visual ability is cataract surgery where the opacified crystalline lens is removed by phacoemulsification and an artificial intraocular lens is implanted. It is estimated that around 10 million cataract operations are performed around the world each year. Cataract operations are generally very successful, with a low risk of serious complications. During the past two decades, cataract surgery underwent tremendous change and modernisation resulting in today's small incision phacoemulsification surgery and a safe technique with a short rehabilitation time for the patient. Traditional spherical monofocal intraocular lenses (IOLs) restore best-corrected vision and may lessen the need for spectacles. These IOLs correct only the spherical portion of the total refractive error and do not correct corneal astigmatism. Astigmatism is a visually disabling refractive error affecting the general population, especially those with cataract. At least 15% to 20% of cataract patients have 1.5 diopters (D) or more of corneal or refractive astigmatism. With increased patient expectations, the trend is not only to remove the cataract but also to address the problem of pre-existing astigmatism at the time of surgery. Surgical-induced astigmatism can be reduced by smaller incisions, i.e. microincision cataract surgery (MICS), which by definition is surgery performed through incisions smaller than 2.0 mm, reducing the need for suturing. This results in better corneal optical quality, thus improving visual outcomes. There are also other surgical options to correct preexisting astigmatism during cataract surgery like: selectively positioning of the phacoemulsification incision; astigmatic keratotomy with corneal or limbal relaxing incisions; excimer laser refractive procedures such as photorefractive keratectomy, laser in situ keratomileusis, and laser-assisted subepithelial keratectomy; or implanting pseudophakic toric posterior chamber intraocular lenses (IOLs). Toric IOLs have been shown to result in good visual and refractive outcomes. Combined with MICS, these IOLs can allow effective correction of cylindrical errors intraoperatively, improving visual quality and thus leading to spectacle independence. Plate haptic and loop haptic toric IOLs have been considered for about a decade but have been associated with postoperative rotational instability. Rotation of a toric lens from its intended orientation degrades its corrective power, with approximately 3.3% loss of cylindrical power for every degree off axis. A misorientation of approximately 30° negates the effectiveness of astigmatic correction, and a misorientation of more than 30° may induce additional astigmatism. Although some patients are asymptomatic despite induced astigmatism, others experience symptoms such as blurred or distorted vision, headache, fatigue, eyestrain, squinting, or eye discomfort. Thus, IOL orientation stability is an essential goal in toric IOL design. RATIONALE The purpose of this study is to assess and compare the axial IOL rotation and optical quality (refraction, visual acuity, decentration and tilt) and capsular bag reaction after micro-incision surgery with an IOL implantation in cataract patients - Acrysof SN60WF, Tecnis ZCB00 & Envista MX60 IOL

The primary objective of this study is to collect safety and effectiveness data for the Technolas Teneo 317 Model 2 excimer laser for LASIK correction in participants with myopia and myopic astigmatism.

The objective of this clinical trial is to evaluate the safety and effectiveness of the Bausch + Lomb Toric Accommodating Posterior Chamber Silicone Intraocular Lens used to provide near, intermediate, and distance vision and a reduction of the effects of preoperative corneal astigmatism in presbyopic patients undergoing cataract extraction and intraocular lens (IOL) placement.

The purpose of this study is to evaluate the safety and effectiveness of the Akreos Toric IOL following cataract surgery.

The purpose of this study is to determine whether the MEL 80 Excimer Laser is effective in the treatment of mixed astigmatism up to 6.0 D, when used as part of the Laser In Situ Keratomileusis (LASIK) procedure.

To evaluate the relative efficacy of orthokeratology, primarily by assessment of changes in central corneal thickness, astigmatism, visual acuity, endothelial cell density, and corneal curvature. To evaluate the relative safety of orthokeratology, primarily by assessment of changes in central corneal thickness, astigmatism, visual acuity, endothelial cell density, induced corneal edema, and epithelial staining. To assess the duration of any orthokeratology treatment effect. To study the mechanisms by which refractive error and visual acuity changes occur, in particular the contribution that comes from changes in corneal curvature and shape. To determine whether there were any predisposing ocular factors that could be used to predict which subjects will experience changes or complications.

Today, cataract surgery is regarded as refractive surgery, mainly aiming emmetropia, and this makes eliminating corneal astigmatism is critical. Corneal astigmatism of more than 1 diopter has been reported in up to 45% of the cataract surgery candidates. It is possible to reduce pre-existing corneal astigmatism by creating a clear corneal incision at the steep meridian of the cornea, however; creating a small incision can correct the only astigmatism up to 1 Diopter, and sometimes this method may not be easy to perform due to the location of steep meridian like the difficulty while creating a superonasal or inferonasal incision at the left eye. This approach is usually sufficient for correcting astigmatism less than 1 D in most eyes. An opposite side clear corneal incision (OCCI) could enhance the flattening effect on the cornea.

The objective of this study is to evaluate uncorrected distance vision and quality of vision as measured by the McAlinden QoV questionnaire 3 months following the final lock-in treatment of the implanted RxSight Light Adjustable Lens (RxLAL) with the Light Delivery Device (LDD) in subjects with preoperative keratometric astigmatism. This is an exploratory study. No primary effectiveness endpoints will be defined.