Search results for "cornea"
showing 10 items of 404 documents
Collagenolytic proteinases in keratoconus.
2006
To study the proteolytic phenomena contributing to the pathogenesis of keratoconus, corneal enzymes with potential to cleave fibrillar collagen were studied.Immunohistochemical labeling was undertaken of conventional and novel mammalian collagenases (MMP-1, -2, -8, -13, and -14) of the matrix metalloproteinase (MMP) family and other collagenolytic proteinases of the serine (human trypsin-2) and cysteine (cathepsin K) endoproteinase families. The results were analyzed using a semiquantitative scoring system.Labeling of MMP-8 was moderate in healthy controls, but weak in keratoconus. Moderate MMP-2 and weak MMP-14 expressions were similar in controls and keratoconus. MMP-1 was slightly overex…
2019
Aims To report corneal topometric and aberrometric values in mucopolysaccharidosis (MPS) and to investigate their correlation with biomechanical corneal parameters. Methods One randomly chosen eye of 20 MPS patients with no to moderate corneal clouding and one eye of 23 healthy controls with comparable age were prospectively included into this study. Corneal surface regularity was assessed by index of surface variance (ISV), -vertical asymmetry (IVA), -height asymmetry (IHA), -height decentration (IHD); keratoconus index (KI), central keratoconus index (CKI) and Zernike indices of anterior and posterior corneal surface using Scheimpflug imaging (Pentacam). Corneal resistance factor (CRF) an…
Visual quality with corneo-scleral contact lenses for keratoconus management
2018
Purpose: To assess the visual quality achieved by fitting corneo-scleral contact lenses (CScL) for keratoconus management. Methods: Thirty patients with keratoconus presented to have CScL fitted because of the unsatisfactory visual quality they experienced with their contact lenses or spectacles. The eye examination included visual acuity assessment, anterior eye biomicroscopy, ocular fundus examination, corneal topographic analysis, endothelialcell count, contrast sensitivity and aberrometry. The fitting process was performed using a diagnostic trial set. Subjective visual quality and comfort, and contact lens wear time were also reported. Patients were monitored for one year. Results: Thr…
Are Ocular Response Analyzer useful to measure corneal hysteresis in patients with intracorneal rings?
2008
Purpose Corneal hysteresis is a viscoelastic property characterized by the difference in behavior under loading and unloading. The aim of the study was to determine corneal hysteresis in different eyes: healthy eyes, keratoconic eyes and keratoconic eyes after intracorneal ring implants. Methods This study comprised 95 eyes of 59 patients. The study population was divided into 3 groups. We analyze 30 healthy human eyes, 35 keratoconic eyes (Amsler grade II-III) and 30 keratoconic eyes after intracorneal rings implantation. Corneal biomechanical properties of these eyes were measured with the Ocular Response Analyser (ORA-Reichert) according to two parameters: corneal hysteresis (CH) and cor…
A simple technique for measurement of corneal thickness.
1998
Measurement of corneal thickness has potential benefit both in the fitting of contact lenses and in monitoring any pathology that could affect corneal thickness. Corneal thickness measurement is undertaken using an accessory to the biomicroscope, the optical pachometer, or by means of expensive apparatus such as the ultrasonic pachometer. There are other complex methods, such as laser Doppler interferometry, or ultrasonic rasters of the cornea. In this study, an easier and low cost method, based on the measurement of the optical section formed of the cornea by the biomicroscope illumination system, is proposed. The advantages of this new method are the simplicity of its experimental set-up …
Posterior chamber phakic intraocular lenses after penetrating keratoplasty.
2009
Purpose To evaluate the efficacy, predictability, and safety of a phakic posterior chamber intraocular Collamer lens (ICL) after penetrating keratoplasty (PKP). Setting Fernandez-Vega Ophthalmological Institute, Oviedo, Spain. Methods A myopic or toric ICL was implanted after PKP in eyes unable to wear glasses or contact lenses and for which corneal laser surgery was contraindicated. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive error, and endothelial cell count were recorded preoperatively and 24 months postoperatively. Results Preoperatively, the 15 eyes had myopia from −2.00 to −17.00 diopters (D) or astigmatism from −1.50 to −7.00 D. …
Corneal thickness differences between type 2 diabetes and non-diabetes subjects during preoperative laser surgery examination
2016
Aims To evaluate the differences in corneal thickness between type 2 diabetes subjects with HbA1c under 7.0% and non-diabetes subjects during their preoperative laser surgery examinations. Methods The mean of five consecutive corneal thickness measurements at the central and mid-peripheral cornea was obtained by means of noncontact scanning-slit corneal topography (Orbscan Topography System II; Orbscan, Inc., Salt Lake City, UT, USA) in 35 myopic non-insulin dependent type 2 diabetes subjects (17 males and 18 females) and 48 healthy myopic controls (23 males and 25 females). Results The corneal thickness values at the central and mid-peripheral cornea were significantly higher in the diabet…
Femtosecond laser for residual refractive error correction after refractive lens exchange with multifocal intraocular lens implantation.
2008
Purpose To assess visual and refractive outcomes of femtosecond laser for residual refractive error correction after refractive lens exchange (RLE) with multifocal intraocular lens (IOL) implantation. Design Prospective, nonrandomized, masked observational case series (self-controlled). Methods Fifty-three eyes of 31 consecutive patients were submitted to femtosecond laser surgery after RLE with multifocal IOL implantation. Patients showed an average manifest refractive error (D) of M , 0.200 ± 0.490; J 0 , −0.051 ± 0.532; and J 45 , −0.007 ± 0.371. Visual acuity (VA) was measured at distance and near vision before and six months after the surgery. Results At six months after surgery, mean …
Optical Quality Comparison between Spherical and Aspheric Toric Intraocular Lenses
2014
Purpose To measure and compare the optical quality of spherical and aspheric toric intraocular lenses (IOLs). Methods Wavefront aberrations of AcrySof Toric and IQ Toric IOLs (Alcon Laboratories) for different powers were measured at 3- and 5-mm pupils by Nimo TR0805 instrument. The Zernike coefficients of trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. The point spread functions (PSFs) of each IOL evaluated were calculated from the wavefront aberrations. The PSF images also were calculated from the IOL wavefront aberrations, adding the cornea's aberrations to simulate the optical quality after their implantation. Results Spherical toric IOLs showed…