Search results for "Presbyopia"
showing 10 items of 51 documents
In vitro power profiles of multifocal simultaneous vision contact lenses.
2013
Abstract Purpose To evaluate the power profile of multifocal contact lenses (CLs) using a new technology based on quantitative deflectometry. Methods The Nimo TR1504 was used to analyze the power distribution of multifocal CLs. The CLs under study were: Air Optix Aqua Multifocal Low, Medium and High Addition and Focus Progressives. Three lenses of each model were considered. Results All multifocal CLs showed a power profile characterized by a change toward more positive power values when aperture sizes become smaller. The near refractive addition of the lenses under study was +2.61 D, +1.44 D, +1.30 D and +0.30 D for the Focus Progressives, the Air Optix Aqua Multifocal High, Medium Add and…
Diffractive corneal inlay for presbyopia
2017
[EN] A conceptually new type of corneal inlays for a customized treatment of presbyopia is presented. The diffractive inlay consists on a small aperture disc having an array of micro-holes distributed inside the open zones of a Fresnel zone plate. In this way, the central hole of the disc lets pass the zero order diffraction and produces an extension of the depth of far focus of the eye, while the diffracted light through the holes in the periphery produce the near focus. Additionally, the micro-holes in the inlay surface fulfill the essential requirement of allowing the flow of nutrients through it to the cells of the corneal stroma. Theoretical and optical-bench experimental results for t…
Imaging Performance of a Diffractive Corneal Inlay for Presbyopia in a Model Eye
2019
[EN] In this work we evaluated the imaging properties of the Diffractive Corneal Inlay (DCI), a novel type of corneal implant working by diffraction that we proposed for the treatment of presbyopia. ZEMAX OpticStudio software was employed for the numerical assessment, with simulations performed in a human-based eye model. In the ray tracing analysis, we used the Modulation Transfer Function (MTF), the Area under the MTF (AMTF), and the Point Spread Function (PSF). The theoretical performance of the DCI under different situations was evaluated in comparison with a commercially available pinhole based corneal inlay. Finally, real images were obtained experimentally in vitro in a model eye wit…
Contrast sensitivity after refractive lens exchange with diffractive multifocal intraocular lens implantation in hyperopic eyes
2008
Contrast Test chart at distance and near under 3 luminance levels (85.0 cd/m 2 , 5.0 cd/m 2 , and 2.5 cd/m 2 ) before and after RLE with bilateral AcrySof ReSTOR IOL implantation in 30 hyperopic eyes with presbyopia and low astigmatism (%1.0 diopter). Results after surgery were compared with those before surgery. RESULTS: Six months postoperatively, the mean residual spherical equivalent refractive error was 0.21 diopter G 0.19 (SD). The best corrected distance and near visual acuities were comparable to those before surgery. For distance vision, the safety index was 1.02 and the efficacy index was 0.91. For near vision, the values were 1.04 and 1.02, respectively. There were no statistical…
ACUITA’ VISIVA, PERFORMANCE DI LETTURA, QUALITA’ DELLA VITA E SENSIBILITA’ AL CONTRASTO SOGGETTIVA ED ELETTROFUNZIONALE IN PAZIENTI AFFETTI DA CATARA…
Presbyopia and the aging eye: Existing refractive approaches and their potential impact on dry eye signs and symptoms.
2020
Every part of the human body is subject to aging, including the eye. Increased prevalence of dry eye disease with age is widely acknowledged: aging threatens ocular surface homeostasis, altering the normal functioning of the lacrimal functional unit and potentially leading to signs and symptoms of dry eye. Parallelly, two additional degenerative processes take place within the crystalline lens, leading to presbyopia and cataractogenesis. With continuously increasing life expectancies both conditions are expected to impact society further. Correction strategies for presbyopia and cataracts either directly or indirectly challenge ocular surface additionally. On one hand, contact lens presbyop…
Presbiopijas korekcija ar multifokālajām intraokulārajām lēcām
2017
Bakalaura darbs ir uzrakstīts angļu valodā uz 47 lapaspusēm. Tas satur 3 zīmējumus, 20 tabulas, 39 literatūras avotus un pielikumu. Darba mērķis ir salīdzināt divu jaunu intraokulāro lēcu (difraktīvā trifokālā lēca un paplašināta fokusa dziļuma multifokālā lēca) efektivitāti presbiopija korekcijā pēc kataraktas operācijas. Pētījumi tika veikti 3 mēnešu periodā pēc kataraktas operācijas, kad tika novērtēta redzes kvalitāte, mērot redzes asumu un kontrasta redzi fotopiskos gaismas un mezopiskos krēslas apstākļos. Abi introokulāro lēcu veidi nodrošināja lielisku redzes asumu visos skata attālumos un pilnu neatkarību no brillēm. Taču kontrasta jūtība un redzes asums mezopiskos krēslas apstākļos…
Redzes funkciju izvērtējums pacientiem agrīnā presbiopijas vecumā ar vienas dienas multifokālajām kontaktlēcām
2017
Bakalaura darbs uzrakstīts uz 27 lapaspusēm, satur 18 zīmējumus, 1 tabulu un 20 literatūras avotus. Darba mērķis ir novērtēt redzes asumu un kontrasta jūtību fotopiskos un mezopiskos apstākļos pacientiem, koriģētiem ar brillēm un vienas dienas multifokālajām kontaktlēcām. Mūsu pētījumi parādīja, ka fotopiskos apstākļos pacientiem pēc korekcijas ar multifokālajām kontaktlēcām redzes asums vidēji samazinājās par 0,02 logMAR vienībām. Mezopiskos krēslas apstākļos pacientiem koriģētiem ar multifokālajām kontaktlēcām redzes asuma samazinājums vidēji bija 0.05 logMAR vienības. Atšķirības redzes asumā ir statistiski nozīmīgas. Kontrasta jūtības vidējie lielumi pēc kontaktlēcu uzlikšanas vidēji sam…
A new trifocal corneal inlay for presbyopia
2021
[EN] Corneal inlays (CIs) are the most recent surgical procedure for the treatment of presbyopia in patients who want complete independence from the use of glasses or contact lenses. Although refractive surgery in presbyopic patients is mostly performed in combination with cataract surgery, when the implantation of an intraocular lens is not necessary, the option of CIs has the advantage of being minimally invasive. Current designs of CIs are, either: small aperture devices, or refractive devices, however, both methods do not have good performance simultaneously at intermediate and near distances in eyes that are unable to accommodate. In the present study, we propose the first design of a …
VisuMax®femtosecond laser for corneal refractive surgery
2008
Femtosecond lasers are increasingly present in ophthalmologic surgical theaters for a variety of reasons. These include faster and better visual outcomes, increased accuracy and predictability for corneal flap thickness in laser in situ keratomileusis procedures. Recent applications of modern femtosecond lasers have broadened the range of uses: keratoplasty, intrastromal segment insertion and even glaucoma and presbyopia surgery. This device profile provides an overview of the advantages of femtosecond lasers in ophthalmic surgery, paying special attention to the new VisuMax® femtosecond laser from Zeiss/Meditec.