Analyse de satisfaction et des performances visuelles après la correction de la presbytie par implant intracornéen Kamra

Évaluer la satisfaction, l'efficacité et la tolérance de l'implant intraoculaire Kamra® (ACI 7000PDT) implanté, en monoculaire, chez des patients presbytes, emmétropes ou amétropes, pour améliorer la vision de près. MATÉRIELS ET MÉTHODES: Cette étude, monocentrique, non randomisée, non comparative chez 18 patients amétropes opérés de LASIK (analyse rétrospective) et 11 patients emmétropes (groupe POCKET, analyse prospective). L'implant était implanté sur l'ceil non dominant, centré sur le vertex, après découpe intrastromale au laser femtoseconde. Nous avons évalué l'acuité visuelle non corrigée (AVNC), corrigée, monoculaire (oeil implanté) et binoculaire, en vision de près (VP), intermédiaire (VI) et de loin (VL) en échelle logMAR (et Monoyer). Nous avons également étudié l'équivalent sphérique (ES), les complications postopératoires et la satisfaction des patients. RÉSULTATS: le groupe LASIK présentait un suivi moyen de 11,2 +- 3,4 mois (min=6 ; max= 24) et un ES moyen préopératoire de 0,38 +- 1,86 (-6,5 ; +1,625). À 1 an 81,8% ont une AVNC binoculaire >= 7/10e et 0,05). À 6 mois 64% des patients ont une AVNC à la fois de loin >=7/10e et de près <= P2. Aucune complication importante n'a été constatée. Un shift hypermétropique moyen de +0,75D était retrouvé à 6 mois, secondaire à un aplatissement cornéen central. 72,7% des patients étaient satisfaits du résultat à 3 mois, 81,8% le sont pour la VP avec un bon éclairage, 100% pour les VL et VI. 36% se plaignaient de vision floue et de sécheresse. CONCLUSION/DISCUSSION: L'implant Kamra® semble être un traitement alternatif sûr et efficace pour la correction de la presbytie chez les patients emmétropes presbytes après un suivi d'1 an.ROUEN-BU Médecine-Pharmacie (765402102) / SudocSudocFranceF

The Gaussian formula and spherical aberration of the static and moving curved mirrors from Fermat's principle

The Gaussian formula and spherical aberrations of the static and relativistic curved mirrors are analyzed using the optical path length (OPL) and Fermat's principle. The geometrical figures generated by the rotation of conic sections about their symmetry axes are considered for the shapes of the mirrors. By comparing the results in static and relativistic cases, it is shown that the focal lengths and the spherical aberration relations of the relativistic mirrors obey the Lorentz contraction. Further analysis of the spherical aberrations for both static and relativistic cases have resulted in the information about the limits for the paraxial approximation, as well as for the minimum speed of the systems to reduce the spherical aberrations.Comment: 15 pages, 7 figures, uses iopart. Major revisions on the physical interpretations of the results. Accepted for publication in J. Op

Assessing the in vitro optical quality of presbyopic solutions based on the axial modulation transfer function.

PURPOSE: To present a metric for assessing the in vitro optical quality of rotationally symmetrical optical elements based on volume calculation under the surface defined by the axial modulation transfer function (MTF). SETTING: University of Valencia, Valencia, Spain. DESIGN: Experimental study. METHODS: The metric volume under the axial MTF was used to assess the optical quality of 2 rotationally symmetrical multifocal intraocular lenses (IOLs) within various defocus intervals (0.50 diopter [D], 0.75 D, and 1.00 D) and at various spatial frequency intervals (7.5 cycles per degree [cpd], 15.0 cpd, and 30.0 cpd). RESULTS: The far focus of the bifocal IOL yielded higher volume values at all spatial frequencies and defocus intervals than the trifocal IOL. The results for the near focus were similar for both IOLs. In addition, the trifocal IOL provided a distinct focus for intermediate vision. CONCLUSIONS: The volume under the axial MTF proved to be a useful tool for objective evaluation of multifocal IOLs. Moreover, it can be applied to evaluate the optical quality of every rotationally symmetrical IOL or optical element. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned

Medium to long term follow up study of the efficacy of cessation of eye-rubbing to halt progression of keratoconus

PurposeTo study the progression of keratoconus after cessation of eye rubbing with a minimum follow up of three-years.DesignRetrospective, monocentric, longitudinal cohort study of keratoconus patients with a minimum of 3 years follow-up.ParticipantsOne hundred fifty three eyes of seventy-seven consecutive patients with keratoconus were included.MethodsInitial examination consisted of anterior and posterior segment evaluation using slit-lamp biomicroscopy. At the initial visit, patients were thoroughly informed of their pathology and instructed to stop rubbing their eyes. Eye rubbing cessation was assessed at all the follow-up visits at 6 months, 1 year, 2 years, 3 years, and yearly afterward. Corneal topography using the Pentacam® (Oculus®, Wetzlar, Germany) was used to obtain maximum and average anterior keratometry readings (Kmax and Kmean), as well as thinnest pachymetry (Pachymin, μm) in both eyes.Main outcome measuresThe main outcomes measured were maximum keratometry (Kmax), mean keratometry (Kmean), and thinnest pachymetry (Pachymin) values at various time points to assess for keratoconus progression. Keratoconus progression was defined as a significant augmentation of Kmax (&gt;1D), Kmean (&gt;1D), or significant diminution of Pachymin (&gt;5%) throughout the total follow-up duration.ResultsOne hundred fifty three eyes of seventy-seven patients (75.3% males) aged 26.4 years old, were followed for an average of 53 months. Over the course of the follow-up, there was no statistically significant variation of ∆Kmax (+0.04 ± 0.87; p = 0.34), ∆ Kmean (+0.30 ± 0.67; p = 0.27) nor ∆Pachymin (−4.36 ± 11.88; p = 0.64). Among the 26 of the 153 eyes which had at least one criterion of KC progression, 25 admitted continuing eye rubbing, or other at-risk behaviors.ConclusionThis study suggests that a significant proportion of keratoconus patients are likely to remain stable if close monitoring and strict ARB cessation are achieved, without the need for further intervention

Considerations of a thick lens formula for intraocular lens power calculation

Background In recent years, some lens manufacturers have committed to providing lens shape data for some of their lens models. The purpose of this study is to present a strategy for prediction of intraocular lens power and residual refraction based on a pseudophakic model eye containing 5 refractive surfaces and to show its applicability using worked examples. Methods A pseudophakic model eye with a thin spectacle correction, a thick cornea (radius of curvatures for both surfaces and central thickness) and a thick IOL (either radius of curvatures RLa and RLp for front and back surface or equivalent power PL and Coddington factor CL; and either central thickness LT or edge thickness and optic diameter) was set up. Calculations were performed based on linear Gaussian optics (vergence formulae). Formulae were provided to derive the lens power/shape and the residual equivalent spectacle refraction SEQ. From the lens shape the location of the haptic plane HP, the image sided principal plane of the lens HL, and the ocular magnification OM were extracted. Results The calculation of a thick intraocular lens and the prediction of residual refraction is presented with reference to 3 working examples: A) lens varied in PL and shifted with its haptic plane keeping the CL constant, B) lens varied in CL and shifted with its haptic plane keeping PL constant, and C) CL and PL of the lens varied keeping its haptic plane position in the eye constant. For each combination of parameters (PL, CL, or haptic plane shift) the parameters influencing SEQ, OM and HL-HP were analysed. Conclusion Some modern optical biometers currently on the market provide the radii of curvature of both corneal surface and all relevant distances in the eye. With additional data on the lens shape, it would be possible to improve lens power calculations by switching from thin to thick lens models for the cornea and for the lens. This would overcome one of the major drawbacks of current lens power calculation methods

Monte‐Carlo simulation of a thick lens IOL power calculation

Background The purpose of this Monte-Carlo study is to investigate the effect of using a thick lens model instead of a thin lens model for the intraocular lens (IOL) on the resulting refraction at the spectacle plane and on the ocular magnification based on a large clinical data set. Methods A pseudophakic model eye with a thin spectacle correction, a thick cornea (curvatures for both surfaces and central thickness) and a thick IOL (equivalent power PL derived from a thin lens IOL, Coddington factor CL (uniformly distributed from −1.0 to 1.0), either preset central thickness LT = 0.9 mm (A) or optic edge thickness ET = 0.2 mm, (B)) was set up. Calculations were performed on a clinical data set containing 21 108 biometric measurements of a cataractous population based on linear Gaussian optics to derive spectacle refraction and ocular magnification using the thin and thick lens IOL models. Results A prediction model (restricted to linear terms without interactions) was derived based on the relevant parameters identified with a stepwise linear regression approach to provide a simple method for estimating the change in spectacle refraction and ocular magnification where a thick lens IOL is used instead of a thin lens IOL. The change in spectacle refraction using a thick lens IOL with (A) or (B) instead of a thin lens IOL with identical power was within limits of around ±1.5 dpt when the thick lens IOL was placed with its haptic plane at the plane of the thin lens IOL. In contrast, the change in ocular magnification from considering the IOL as a thick lens instead of a thin lens was small and not clinically significant. Conclusion This Monte-Carlo simulation shows the impact of using a thick lens model IOL with preset LT or ET on the resulting spherical equivalent refraction and ocular magnification. If IOL manufacturers would provide all relevant data on IOL design data and refractive index for all power steps, this would make it possible to perform direct calculations of refraction and ocular magnification

The Efficacy of an Acrylic Intraocular Lens Surface Modified with Polyethylene Glycol in Posterior Capsular Opacification

To investigate if the surface modification of intraocular lens (IOL) is efficient in the prevention of posterior capsular opacification (PCO), the acrylic surface of intraocular lens (Acrysof®) was polymerized with polyethylene glycol (PEG-IOL). The human lens epithelial cells (1×104 cells/mL) were inoculated on PEG grafted or unmodified acrylic lenses for the control. The adherent cells on each IOL surface were trypsinized and counted. The every PEG-IOL was implanted in 20 New Zealand rabbits after removal of crystalline lens. The formations of PCO were checked serially through retroilluminated digital photography, and the severity scores were calculated using POCOman®. The cell adherence patterns on each IOL were examined by scanning electron microscopy. As a result, the mean number of adherent cells of PEG-IOL (3.2±1.1×103) tended to be smaller than that of the acrylic controls (3.6±1.9×103) without a statistical significance (p=0.73). However, the mean severity of PCO formation in PEG-IOL was significantly lower than that in the control during the third to sixth weeks after surgery. Scanning electron microscopy revealed that the more patch-like cells were found firmly attached to the IOL surface in control than in the PEG-IOL. Conclusively, PEG polymerization to the acrylic IOL would possibly lessen the formation of PCO after cataract removal