Active clinical trials for "Astigmatism"

This study is to evaluate the necessity of considering posterior corneal toricity on refractive outcome of patients with cataracts and corneal astigmatism after implantation of intraocular lenses. This is determined by comparing total corneal and refractive astigmatism,and by comparing the expected refractive result with actual refractive astigmatism postoperatively,using total corneal and anterior corneal astigmatism to calculate respectively.

This study is aimed at examining the BCVA from try-on glasses constructed from measurements from the EyeQue VisionCheck.

This study included patients who visit for refractive surgery (photorefractive keratectomy, photorefractive keratectomy with with corneal collagen cross linking, laser in situ keratomileusis, small incision lenticule extraction), phakic Intraocular Lens implantation (Implantable Collamer Lens, artiflex), and cataract surgery. Patients will be examined whether iris recognition scanner of smartphone works before and after surgery. In addition, before and after pupil dilation (5mm, 6mm, 7mm, 8mm), patients will be examined whether iris recognition scanner of smartphone works well.

Toric intraocular lens (IOL) is now widely used for the cataract surgery with preoperative corneal astigmatism. Symptomatic epiretinal membrane (ERM) is often treated with 25-gauge transconjunctival sutureless vitrectomy, resulting in good visual recovery. So far, however, limited information is available on the the stability of axis rotation, astigmatism correction, and improvement in uncorrected distance visual acuity, using astigmatism-correcting IOL in a 25-gauge transconjunctival sutureless vitrectomy combined with cataract surgery. In the current study, eyes with a preoperative corneal cylinder of more than 0.75 diopter had a triple procedure for idiopathic ERM using a toric IOL. Outcome measures will be the amount of IOL axis rotation, uncorrected visual acuity, corrected distance visual acuity, and corneal and refractive astigmatism up to 6 months postoperatively. We are expecting to show that postoperative IOL axis stability is similar to that reported for cataract surgery alone in vitrectomy (triple procedure) for idiopathic ERM with a toric IOL.

This is a randomised controlled trial that formally compares intra-ocular lenses, which can be used in cataract surgery, one of which is the standard 'monofocal' lens, and the other is the newer toric lens which can correct astgimatism. The null hypothesis is that both intra-ocular lenses give the same visual outcome in cataract surgery. The alternative hypothesis is that the toric lens, provides a better unaided (without glasses) vision, by correcting the participant's astigmatism. It has been decided to conduct a randomised controlled trial of the two lenses, as although the toric lenses are endorsed by many case series (which show a reduction in astigmatism), they have not been formally compared to the standard lens. An RCT will enable the formal comparison. It is expected that this trial will take approximately a year to conduct: six months of recruitment and six months of follow-up. A further six months will be required to analyse the data and prepare a manuscript for publication. The investigators do not plan to conduct an interim analysis or report as this is a short-trial (six months follow-up) using two alternative lens that are CE marked and already widely used. Participants who have both cataract and astigmatism will be identified from the GP/optometrist referral letter. They will be seen in specially designated clinics for this research study, which will run alongside the routine cataract 'one' stop clinics at St Richard's Hospital and Worthing Hospital. This will allow for those patients who wish to be part of the study to have all the necessary examination done in one visit and for those who decline participation to be seen in the regular cataract clinic. Potential participants will be sent the research trial information (appendix A) with their appointment letter. After introducing himself the researcher (who is also a senior cataract surgeon at Western Sussex Hospital Trust), will check if potential participants have had the opportunity to read the trial information that they were sent, or give participants a further copy as required. The key points of the trial will be re-iterated by the researcher and they will be invited to ask any questions about the trialThe researcher will check that the potential participant has read and understood the participant information leaflet. They will answer any questions that the potential participant has and will then take signed consent from those willing to participate. Only one eye (the 'trial eye') from each patient will be used in the trial. In patients with bilateral cataract, one eye will be selected as the trial eye. This will be the eye that the participant prefers, after consultation with the researcher or surgeon, to have operated first. The participant will be allocated a unique study reference number. Patients who decline to take part in the trial will be offered cataract surgery as per usual WSHT/NHS procedure.

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 recently introduced toric V4c toric ICL (STAAR Surgical Company, Monrovia, CA, USA) has been designed with a 360-µm central hole to allow aqueous humor to flow without the need for an iridotomy. As far as the investigators certain, there have been not well-established prospective studies on the role of the V4c toric ICL for myopic astigmatism correction. Therefore, the present study aimed to investigate the clinical outcomes and rotational stability and to analyze factors that influence the rotational stability in V4c toric ICL implanted eyes prospectively.

Prospective, comparative, randomized, non-masked clinical study to compare the a digital refraction with LogMAR VA testing utilizing trial lenses, to standard manual refraction using a Phoropter, and LogMAR VA testing, in accuracy of visual acuity measurement.

The aim of this dispensing study is to evaluate the clinical performance of existing wearers of Avaira toric lenses following a refit with Clariti toric over 1 month of daily wear.

The purpose of this study is the investigation of biomechanical properties of the cornea using computer-aided data analysis. Currently, it is known that keratoconus and glaucoma are ocular disease that are associated with biomechanical alterations of the cornea. Corneal ectasia, especially keratoconus, is a corneal disease that leads to an irreversible loss of visual acuity while the cornea becomes steeper, thinner and irregular. For these patients, surgical intervention (e.g. corneal cross-linking) is performed, in case of disease progression. In glaucoma, the information about corneal alterations serves in two ways, first, correct measurement of intra ocular pressure (IOP); second, early diagnosis of suspects before visual field defects are detectable. Especially, the Corvis ST is an air-puff tonometer that measures intraocular pressure, corneal thickness (CCT) as well as dynamic corneal response (DCR) parameters. Most of the DCR parameters are affected by IOP and CCT: Therefore, algorithm are needed to determine parameters without impact of IOP and CCT that are describe the biomechanical properties of the cornea.