View clinical trials related to Astigmatism.
Filter by:In an aging population, cataract and presbyopia become increasingly common. A cataract is the opacification of the natural crystalline lens inside a person's eye, causing reduction of vision. Presbyopia is an age related condition resulting in loss of reading/near vision which results in requiring reading glasses. Astigmatism is a common condition characterized by an abnormal cornea (the clear tissue at the front of the eye) which results in blurred distance and near vision, again requiring glasses. Cataract surgery is the most common elective surgery worldwide for patients over 65. It is composed of removal the cataract and insertion of a new intraocular lens (IOL). Currently only monofocal IOLs are available on the National Health Service (United Kingdom) - meaning they give good distance or near vision. The majority of patients opt for good distance vision with glasses to read. The investigators are trialling insertion of a new Extended Depth of Focus (enhanced aspheric) Toric IOL (EDoF Toric IOL), which treats all 3 conditions - cataract, presbyopia and astigmatism. All patients attending St Thomas' hospital for treatment of cataracts, who have presbyopia and astigmatism will be considered for invitation to the study. Patients who participate in the study will be randomly selected to receive either the new IOL - the TECNIS Eyhance Toric II IOL, or a well-established IOL the Alcon Acrysof IQ Toric IOL during cataract surgery. Insertion of the Alcon Acrysof IQ Toric IOL is known to treat cataract and astigmatism but not presbyopia. Patients will be assessed and have their surgery performed at St Thomas' Hospital London. They will have 7 appointments over 12 months, plus surgery. The investigators hope to demonstrate better distance, intermediate and near vision and increased spectacle independence in the TECNIS Eyhance Toric II IOL group. EDoF Toric IOLs have the potential to transform cataract surgery outcomes for patients in the NHS.
Multicenter, prospective, single-arm, observational, non-interventional post market clinical investigation (registry study) with the overall objective to assess safety and performance of CLEAR in a real world setting.
Corneal astigmatism is refractive error that impairs uncorrected visual acuity. When patients undergo cataract surgery, implantation of toric IOL is deemed the most effective choice for correcting corneal astigmatism and reducing postoperative spectacle dependence. Previous studies report that the visual effects and rotational stability of toric IOLs are well maintained over 1- or 2-year follow-up periods. However, the long-term changes in the effects of toric IOLs remain unclear.
The planned clinical investigation will be conducted to acquire raw data for the development of the algorithm. The data acquisition is intended to obtain first impressions of the potential performance of the changed hardware and software components and to confirm the safety profile assessed by risk analysis.
Cataract surgery by phacoemulsification is the most commonly performed procedure in Pakistan. Cataract surgery aims for visual rehabilitation and freedom from all kinds of eyewear. Pre-operative corneal astigmatism greater than 1.0 Diopter is reported in 42% preoperatively and 58%postoperatively after implanting a monofocal intraocular lens(IOL). Visual acuity tended to worsen postoperatively with increased astigmatism4. Different treatment modalities are used to reduce astigmatism, like toric IOL. Limbal relaxing incision, actuate keratotomy, intrastromal rings, Lasik and femtosecond laser. Most of these modalities are expensive, so they cannot be afforded by the patients as Pakistan is a low-income country with a per capita income of US$1,562 (160th worldwide)
Corneal astigmatism is refractive error that impairs uncorrected visual acuity. When patients undergo cataract surgery, implantation of toric IOL is deemed the most effective choice for correcting corneal astigmatism and reducing postoperative spectacle dependence. The IOL-capsular complex is formed after cataract surgery and intraocular lens (IOL) implantation. Early postoperative mechanical wrapping of the anterior and posterior capsules plays a significant role in preventing IOL decentration and tilt, as well as formation of the IOL-capsular complex which reduces the incidence of posterior cataract opacity. IOL decentration ≥ 0.4 mm or/and IOL tilt ≥7degree were considered clinically significant because of poor post-surgery visual quality especially for optical sophisticated IOLs such as toric IOLs. IOL instability could decrease the curative effect of toric IOL. There are numerous types of toric IOLs; however, AcrySof IQ and TECNIS toric IOL are most frequently used in the Ophthalmology Hospital of Wenzhou Medical University. AcrySof IQ IOL has some differences compared with TECNIS toric IOL. IQ has a modified L haptic design while TECNIS® toric IOL has a modified C haptic design. AcrySof IQ IOL has a discontinuous 360˚ posterior square edge while TECNIS toric IOL has a continuous 360˚ posterior square edge. The AcrySof IQ IOL cylinder power models include 1.00, 1.50, 2.25, 3.00, 3.75, 4.50, 5.25 and 6.00 D. The Tecnis IOL cylinder power models include 1.00, 1.50, 2.25, 3.00 and 4.00 D. Previous study pointed that patients with cataracts with corneal astigmatism achieved comparable improvement in visual acuity, astigmatism correction, CS（sensitive contrast）, rotational stability and satisfaction, following AcrySof and TECNIS toric IOL implantation. However，some other studies found that the Acrysof toric IOL showed significantly greater rotational stability than the Tecnis toric IOL and the rate of surgical IOL repositioning was higher in eyes implanted with TECNIS than with AcrySof toric IOLs for astigmatic correction. Currently, there is no literature guidance to compare the results of cataract surgery combined various types of toric IOLs implantation in patients using CASIA2. The novel anterior segment optical coherence tomography (AS-OCT) device, CASIA2 can accurately evaluate the IOL capsule bending and the lens position after cataract surgery. Also, CASIA2 can be used to documented the dynamic changes of IOL-capsular complex after surgery.
To determine the effectiveness of correcting astigmatism by laser refractive surgery by a vectorial astigmatism outcome analysis that uses 3 fundamental vectors : target induced astigmatism vector ( TIA) , surgically induced astigmatism vector , and difference vector , as described by Alpins method.
To assess visual performance, refractive outcome, and patient satisfaction with the use of "off the shelf" toric lenses, with a set cylindrical correction of 2.00 or 4.00 diopters, and combined limbal relaxing incisions and/or off-axis intraocular lens rotation, compared to fully targeted toric intraocular lens correction.
Keratoconus is a bilateral (but usually asymmetrical) non-inflammatory progressive thinning process of the cornea. It manifests as characteristic cone-like ectasia of the cornea associated with irregular stromal thinning, resulting in a cone-like bulge , which causing irregular astigmatism and vision impairment.
This study investigates the effects of trabeculectomy and combined phacoemulsification plus trabeculectomy on corneal astigmatism.