View clinical trials related to Corneal Wavefront Aberration.
Filter by:To explore whether cornea structure, and optical quality are affected by the covid-19 infection.
Identification of the correlation between angle kappa , corneal high order aberrations and total eye aberrations in myopic hyperopic and astigmatic patients
selective alpha-2 receptor agonists cause changes in intraocular pressure and pupillary size thus may affect patient quality of life.
Aberrations are the spreading of light from a point focus. Aberrations of the eyes can be objectively evaluated with a wavefront aberrometer. Lower order aberrations such as defocus and astigmatism can be corrected with glasses and traditional/disposable soft contact lenses. Patients with ectatic corneal disease, such as keratoconus, or irregular astigmatism cause by surgery, trauma or disease, experience vision that is unlikely to be adequately corrected with glasses or disposable soft contact lenses due to higher order aberrations (HOA). HOA's cause halos, flare, glare, starbursts, doubling, smearing or ghosting of vision. Specialty contact lenses, such as scleral lenses, can be used to mask the irregularity of the cornea, reducing HOA's and improving vision. In many patients the resultant vision, though improved, still has some level of residual HOA's affecting the quality of vision. Custom scleral lenses with customized wavefront guided optics can be used to reduce residual HOA's and improve vision further. These lenses have been referred to as higher order aberration correcting scleral lenses or HOA correcting sclerals and wavefront guided scleral lenses or WFG sclerals.
A holographic optical coherence tomography (H-OCT) setup is used to detect the wavefront by means of phase reconstruction.
The investigators are proposing this research project to: 1. Screen a set of patients after normal cataract surgery with a single focus lens aimed at good distance vision at 3 months after surgery to identify patients who are able to see and read well without glasses. 2. Identify the combination of factors responsible for this phenomenon in the patients who are achieving this. Potentially eligible patients will be given an invitation letter and patient information sheet on the day they arrive for surgery. They will then be asked if they are happy to be contacted by phone 2-4 weeks post-surgery with a view to booking them into an additional research visit at 3 months after their surgery. At 3 months after surgery they will have their un-corrected vision checked. They will also have their reading speed assessed without any glasses. They will undergo a through refractive check by an optometrist to assess the power of the spectacles (if needed) and following this they will have a scan of the eye (a technique known as wave front analysis which uses very sophisticated optics) to capture the optical distortions in the structures of the eye. If this study is able identify factor/s responsible for giving good unaided reading and distance vision then this factor can be reproduced in eyes undergoing cataract surgery. This will mean that the patients can have an increased option of spectacle independence without the need for expensive multifocal IOLs and their associated side effects such as glare and halos, particularly at night.
Refractive surgeries can be divided into two distinct categories: 1) corneal surgeries (superficial and deep procedures) carried on the surface of the eye and 2) lens surgeries (phakic IOL, refractive lens exchange) - an intraocular intervention, performed in the anterior or posterior chamber or on the lens. In the proposed protocol focus is on the corneal refractive surgeries impact on monochromatic higher-order aberrations on the one hand and chromatic aberrations on the other. During the surgery in order to get the patient emmetropic, refractive surgery corrects optical defects by decreasing aberrations of lower orders ) simultaneously increases high-order aberrations (that is perceived by the patient as halo, glare or starburst). Informations about prevalence and causes of higher order aberrations after refractive surgery are numerous but there is no information about chromatic aberrations.
Aberrations play a significant role in the visual process and can be divided in lower-order and higher-order aberrations. The former can be measured using the commercially available IOL Master (Carl Zeiss Meditec AG, Germany) and have profound influence on visual acuity. Higher-order aberrations do not significantly influence visual acuity but affect the quality of vision and can cause halos, double vision, and night vision disturbances. Background Cataract surgery has become a routine procedure in the developed countries. During this surgery, a foldable intraocular lens is usually inserted into the capsular bag. However, these lenses do not account for individual optical biometry data or aberrations. Therefore, it is important to provide data for ametropic and emmetropic eyes as this information might improve future intraocular lens design and lead to individually adapted lenses for yielding optimal visual acuity and quality results. The aim of the present study is to clarify the correlation between refractive errors/axial eye length and spherical aberrations of the cornea.