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Intraocular Lenses (intraocular + lense)

Distribution by Scientific Domains
Medical Sciences100%

Kinds of Intraocular Lenses

  • toric intraocular lense
    		•

    Selected Abstracts

    Intraocular lenses in children

    ACTA OPHTHALMOLOGICA, Issue 7 2007
    Michael O'Keefe
    No abstract is available for this article. [source]

    Letter to the Editor: Assessing the optical performance of multifocal (diffractive) intraocular lenses

    OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 2 2009
    Michael J. Simpson
    No abstract is available for this article. [source]

    Computerized calculation scheme for bitoric eikonic intraocular lenses

    OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2003
    Achim Langenbucher
    Abstract Despite full correction of the corneal astigmatism with toric intraocular lenses, the retinal image is distorted and the lateral image-object magnification is different in different meridians. The purpose of this study is to describe an iteration strategy for tracing an axial pencil of rays through the ,optical system eye' containing astigmatic refractive surfaces with their axes at random to calculate a thick bitoric lens implant which eliminates image distortion. The capabilities of this computing scheme are demonstrated with two clinical examples. We present a mathematically straightforward computer-based strategy for the calculation of thick bitoric eikonic lens implants. The iteration algorithm is initialized with a spherical front and a toric back surface and stepwise decreases the image distortion by adding cylinder lenses to the front lens surface corrected by the toric lens back surface. Total magnification can be modulated by varying the front-to-back surface power of the thick lens. [source]

    3424: Posterior capsule opacification assessment and factors that influence visual quality after posterior capsulotomy

    ACTA OPHTHALMOLOGICA, Issue 2010
    R MICHAEL
    Purpose To study the correlation between posterior capsule opacification (PCO) and intraocular straylight and visual acuity. Methods We measured visual acuity (VA) (logMAR) and intraocular straylight (C-Quant straylight parameter log[s]) under photopic conditions before and 2 weeks after YAG capsulotomy in 41 patients (53 eyes) from the Centro de Oftalmología Barraquer in Barcelona and the University Eye Clinic, Paracelsus Medical University in Salzburg. Photopic pupil diameter was also measured. To document the level of opacification, pupils were dilated, and photographs were taken with a slit lamp, using retroillumination and the reflected light of a wide slit beam at an angle of 45º. PCO was subjectively graded on a scale of 0 to 10 and using the POCOman system. A multiple regression analysis was performed to evaluate factors that influence straylight after capsulotomy. Results Straylight correlated well with retroillumination and reflected-light PCO scores, whereas VA only correlated with retroillumination. Both VA and straylight improved after capsulotomy. Straylight values varied widely after capsulotomy. Multiple regression analysis showed that older age, large ocular axial length, hydrophobic acrylic intraocular lenses (IOLs), and small capsulotomies are factors that increased intraocular straylight. Conclusion Intraocular straylight is a useful tool in the assessment of PCO. It correlates well with PCO severity scoring methods. When performing a posterior capsulotomy, factors such as age, IOL material, axial length, and capsulotomy size must be taken into consideration, as they influence intraocular straylight. [source]

    4431: Wavefront aberration variations with aspheric toric intraocular lenses

    ACTA OPHTHALMOLOGICA, Issue 2010
    PJ PISELLA
    [source]

    Ocular wavefront analysis and contrast sensitivity in eyes implanted with AcrySof IQ or AcrySof Natural intraocular lenses

    ACTA OPHTHALMOLOGICA, Issue 7 2009
    Tamer Takmaz
    Abstract. Purpose:, This study aimed to compare ocular wavefront aberrations for pupil diameters of 4 mm and 6 mm, and contrast sensitivity, in eyes with AcrySof IQ and AcrySof Natural intraocular lenses (IOLs). Methods:, Sixty eyes of 60 patients were enrolled in this prospective randomized study. After phacoemulsification the eyes received either AcrySof IQ SN60WF or AcrySof Natural SN60AT IOLs. One month after surgery, all patients underwent complete ophthalmological examination including corneal topography, wavefront analysis for pupil diameters of 4 mm and 6 mm, and contrast sensitivity measurements with the CSV 1000E instrument under photopic and mesopic conditions with and without glare. Results:, There was no statistically significant difference between groups in age, sex or other preoperative ocular characteristics (p > 0.05). Patients with AcrySof IQ IOLs had higher contrast sensitivity at 6 c.p.d. under photopic conditions, at 6 c.p.d. and 18 c.p.d. under mesopic conditions, and at 6 c.p.d., 12 c.p.d. and 18 c.p.d. under mesopic conditions with glare (p < 0.05). Corneal spherical aberration was 0.273 ± 0.074 ,m in the AcrySof Natural group and 0.294 ± 0.086 ,m in the AcrySof IQ group (p = 0489). Ocular spherical aberration was 0.362 ± 0.141 ,m and 0.069 ± 0.043 ,m (p < 0.001) for 6-mm diameter pupils and 0.143 ± 0.091 ,m and 0.017 ± 0.016 ,m (p < 0.001) for 4-mm diameter pupils, with AcrySof Natural and AcrySof IQ IOLs, respectively. There were no significant differences in other higher-order aberrations between the groups (p > 0.05). Conclusions:, Aspherical AcrySof IQ IOLs significantly reduced spherical aberration for pupil diameters of both 4 mm and 6 mm and also improved contrast sensitivity more than spherical AcrySof Natural IOLs, especially in mesopic conditions. [source]

    Nanostructural properties of intraocular lenses (IOLs) , atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) investigations

    ACTA OPHTHALMOLOGICA, Issue 2009
    E WYLEGALA
    Purpose To investigate and analyze surface of explanted intraocular lenses (IOL-s), by means of the Atomic Force Microscope (AFM) and Fourier transform infrared spectroscopy (FTIR). Methods Eight dry IOL-s (acrylic: SN60AT , 3 pieces, SA60AT , CZ70BD; silicone: CLRFLXC; "hard": AJPR,CP65T), and four hydrophilic acrylic IOL-s (AC-IOL and PC- IOL, both: naïve and removed during keratoplasty) were imaged (topography and phase) with AFM. AFM is used to investigate, at nanoscale, the surfaces' topography and some nanomechanical properties (eg. elasticity, hardness) of materials in medicine. The samples can be investigated in quasi-physiological conditions, usually no damaging preparation is required. For the acrylic and "hard" lenses the granular nanostructure is observed. The roughness of the lenses' surfaces can be then assessed. The silicone lens is soft: the forces of nanonewtons applied during imaging cause strong deformations of the material. Results Nanomechanical properties of PC-IOL lens are not uniform. This may be advantageous for its calcification: for the lens of the same type removed during keratoplasty strong calcification is observed. For SN60AT lens the influence of the application process (folding) on its nanostructure is tested. The observed structural nano-defects are permanent, they can occur during folding or can be caused by the used equipement. The similar nano-deformations are observed for the removed AC-IOL lens. Conclusion AFM and FTIR showed to be a high-resolution imaging tool for the scanning of surface IOL. [source]

    Computerized calculation scheme for retinal image size after implantation of toric intraocular lenses

    ACTA OPHTHALMOLOGICA, Issue 1 2007
    Achim Langenbucher
    Abstract. Purpose., To describe a paraxial computing scheme for tracing an axial pencil of rays through the ,optical system eye' containing astigmatic surfaces with their axes at random. Methods., Two rays (,10 prism diopters from vertical and horizontal) are traced through the uncorrected and corrected eye. In the uncorrected eye one specific ray is selected from the pencil of rays, which passes through the pupil center. In the corrected eye any ray can be traced through the eye. From the slope angle, the intersection of the ray with the refractive surface and the refraction the slope angle of the exiting ray is determined and the ray is traced to the subsequent surface. From both rays traced through the eye an ellipse is fitted to the image to characterize the image distortion of an circular object. Example., Assumptions: target refraction ,0.5,1.0D/A = 90° at 14 mm, corneal refraction 42.5 + 3.5D/A = 15°, axial length 23.6 mm, IOL position 4.6 mm, central lens thickness 0.8 mm, refractive index 1.42, front/back surface of the toric IOL 10.0 D/7.14 + 6.47D/A = 101.8°. The vertical incident ray was imaged to (x, y) = (0.0055 mm, ,1.6470 mm)/(0.0067 mm, ,1.6531 mm) in the uncorrected/corrected eye. The horizontal incident ray was imaged to (x, y) = (1.6266 mm, ,0.0055 mm)/(1.6001 mm, ,0.0067 mm) in the uncorrected/corrected eye. The ellipse (semi-major/semi-minor meridian) fitted to the conjugate image of a circle sized 1.648 mm/1.625 mm in an orientation 14.2° in the uncorrected and 1.654 mm/1.599 mm in an orientation 7.1° in the corrected eye. Conclusion., This concept may be relevant for the assessment of aniseikonia after implantation of toric intraocular lenses for correction of high corneal astigmatism. [source]

    Five-year follow-up of posterior capsule opacification with two different silicone intraocular lenses

    ACTA OPHTHALMOLOGICA, Issue 6 2006
    Karin Sundelin
    No abstract is available for this article. [source]

    Paediatric intraocular lenses: the power to choose?

    CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2007
    Penny McAllum FRANZCO
    No abstract is available for this article. [source]

    Operated and unoperated cataract in Australia

    CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 2 2000
    Catherine A McCarty PhD MPH
    ABSTRACT Purpose: To quantify the prevalence of cataract, the outcomes of cataract surgery and the factors related to unoperated cataract in Australia. Methods: Participants were recruited from the Visual Impairment Project: a cluster, stratified sample of more than 5000 Victorians aged 40 years and over. At examination sites interviews, clinical examinations and lens photography were performed. Cataract was defined in participants who had: had previous cataract surgery, cortical cataract greater than 4/16, nuclear greater than Wilmer standard 2, or posterior subcapsular greater than 1 mm 2. Results: The participant group comprised 3271 Melbourne residents, 403 Melbourne nursing home residents and 1473 rural residents. The weighted rate of any cataract in Victoria was 21.5%. The overall weighted rate of prior cataract surgery was 3.79%. Two hundred and forty-nine eyes had had prior cataract surgery. Of these 249 procedures, 49 (20%) were aphakic, 6 (2.4%) had anterior chamber intraocular lenses and 194 (78%) had posterior chamber intraocular lenses. Two hundred and eleven of these operated eyes (85%) had best-corrected visual acuity of 6/12 or better, the legal requirement for a driver's license. Twenty-seven (11%) had visual acuity of less than 6/18 (moderate vision impairment). Complications of cataract surgery caused reduced vision in four of the 27 eyes (15%), or 1.9% of operated eyes. Three of these four eyes had undergone intracapsular cataract extraction and the fourth eye had an opaque posterior capsule. No one had bilateral vision impairment as a result of cataract surgery. Surprisingly, no particular demographic factors (such as age, gender, rural residence, occupation, employment status, health insurance status, ethnicity) were related to the presence of unoperated cataract. Conclusions: Although the overall prevalence of cataract is quite high, no particular subgroup is systematically under-serviced in terms of cataract surgery. Overall, the results of cataract surgery are very good, with the majority of eyes achieving driving vision following cataract extraction. [source]