Purpose: To develop and implement an algorithm for simulation of photorefractive surgery. It is well known that many flying-spot lasers in the market have limitations in correcting higher order aberrations, but there is little quantitative information about errors related to aberration complexity.
Methods: By applying known surfaces described by Zernike polynomials of different orders it was possible to simulate several target surfaces that may well resemble in vivo cases of refractive surgery candidates. An algorithm that uses the mathematical concept of convolution was implemented and several simulated surfaces were tested, ranging from low order aberrations (sphere-cylinder) to 10th order aberrations, (high orders of coma, spherical aberration, trefoil, etc).
Results: the results show that the laser profile and diameter are critical factors when considering the correction of higher order aberrations.
Conclusions: Not all aberrations of the same high order induce the same amount of error - spherical aberrations are shown to be far more difficult to correct than higher order aberrations related to angular frequency.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1590/s0004-27492007000600006 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
A critical view of silk fibroin for non-viral gene therapy.
Int J Biol Macromol
January 2025
National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, No. 199 Ren'ai Road, Industrial Park, Suzhou 215123, PR China. Electronic address:
Exogenous genes are inserted into target cells during gene therapy in order to compensate or rectify disorders brought on by faulty or aberrant genes. However, gene therapy is still in its early stages because of its unsatisfactory therapeutic effects which are mainly due to low transfection efficiency of vectors, high toxicity, and poor target specificity. A natural polymer with numerous bioactive sites, good mechanical qualities, biodegradability, biocompatibility, and processability called silk fibroin has gained attention as a possible gene therapy vector.
View Article and Find Full Text PDFStudy on Visual Quality After Cataract Surgery and Goniosynechialysis in Patients with Primary Angle-Closure Glaucoma and Cataracts.
Clin Ophthalmol
January 2025
Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, Sichuan Province, 637000, People's Republic of China.
Objective: To assess the visual quality in patients with primary angle-closure glaucoma (PACG) complicated by cataracts after cataract phacoemulsification with intraocular lens (IOL) implantation and goniosynechialysis, and to explore the relationship between pupil size and visual quality.
Methods: A retrospective, non-randomized study was conducted, including 65 PACG patients (75 eyes) who underwent cataract surgery with IOL implantation and goniosynechialysis from July 2021 to June 2023, as well as a control group of cataract-only patients. Visual quality was evaluated using objective and subjective methods at least 3 months postoperatively.
Impact of central corneal astigmatism on postoperative visual outcomes in patients undergoing trifocal intraocular lens implantation.
BMC Ophthalmol
January 2025
Department of Ophthalmology, Eye & ENT Hospital, Fudan University, 83 Fenyang Road, Xuhui District, Shanghai, 200031, China.
Background: To investigate the impact of central corneal astigmatism on postoperative visual outcomes in patients with trifocal intraocular lens (IOL) implantation.
Methods: This retrospective study included 278 eyes of 278 patients who underwent uneventful cataract surgery with implantation of the trifocal IOL (AT LISA tri 839MP). Patients were divided into two groups according to the total corneal refractive power (TCRP) in 3 mm zone centered on the corneal apex: low astigmatism group, TCRP ≤ 0.
Pericytes in Glioblastoma: Hidden Regulators of Tumor Vasculature and Therapy Resistance.
Cancers (Basel)
December 2024
Research Group on Tumors of the Central Nervous System, Pathology Department, University of Valencia, 46010 Valencia, Spain.
Glioblastoma IDH wild type (GB), the most common malignant primary brain tumor, is characterized by rapid proliferation, extensive infiltration into surrounding brain tissue, and significant resistance to current therapies. Median survival is only 15 months despite extensive clinical efforts. The tumor microenvironment (TME) in GB is highly specialized, supporting the tumor's aggressive behavior and its ability to evade conventional treatments.
View Article and Find Full Text PDFNeglect symptoms are related to a prediction-hypersensitivity in ipsilesional space.
Cortex
December 2024
Cognitive Neuroscience, Institute of Neuroscience & Medicine (INM-3), Forschungszentrum Jülich, Jülich, Germany; Department of Neurology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany.
The precise cognitive mechanisms underlying spatial neglect are not fully understood. Recent studies have provided the first evidence for aberrant behavioral and electrophysiological prediction and prediction error responses in patients with neglect, but also in right-hemispheric (RH) stroke patients without neglect. For prediction-dependent attention, as assessed with Posner-type cueing paradigms with volatile cue-target contingencies, studies in healthy volunteers point to a crucial role of the right temporo-parietal junction (rTPJ) - as part of a network commonly disrupted in neglect.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!