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

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

Performance of a simplified strategy for formula constant optimisation in intraocular lens power calculation

Purpose: To investigate the performance of a simple prediction scheme for the formula constants optimised for a mean refractive prediction error. Methods: Analysis based on a dataset of 888 eyes before and after cataract surgery with IOL implantation (Hoya Vivinex). IOLMaster 700 biometric data, power of the implanted lens and postoperative spherical equivalent refraction were used to calculate the optimised constants (.)opt for SRKT, HofferQ, Holladay and Haigis formula with an iterative nonlinear optimisation. For detuning start values by ±1.5 from (.)opt, the predicted formula constants (.)pred were calculated and compared with (.)opt. Formula performance metrics mean (MPE), median (MEDPE), mean absolute (MAPE), median absolute (MEDAPE), root mean squared (RMSPE) and standard deviation (SDPE) of the formula prediction error were analysed for (.)opt and (.)pred. Results: (.)pred – (.)opt showed a 2nd order parabolic behaviour with maximal deviations up to 0.09 at the tails of detuning and a minimal deviation up to −0.01 for all formulae. The performance curves of different metrics of PE as functions of detuning variations show that the formula constants for zeroing MPE and MEDPE yield almost identical formula constants, optimisation for MAPE, MEDAPE and RMSPE yielded formula constants very close to (.)opt, and optimisation for SDPE could result in formula constants up to 0.5 off (.)opt which is unacceptable for clinical use. Conclusion: This simple prediction scheme for formula constant optimisation for zero mean refraction error performs excellently in our monocentric dataset, even for larger deviations of the start value from (.)opt. Further studies with multicentric data and larger sample sizes are required to investigate the performance in a clinical setting further

Diffuse laser illumination for Maxwellian view Doppler holography of the retina

We describe the advantages of diffuse illumination in laser holography for ophthalmology. The presence of a diffusing element introduces an angular diversity of the optical radiation and reduces its spatial coherence, which spreads out the energy distribution of the illumination beam in the focal plane of the eyepiece. The field of view of digitally computed retinal images can easily be increased as the eyepiece can be moved closer to the cornea to obtain a Maxwellian view of the retina without compromising ocular safety. Compliance with American and European safety standards for ophthalmic devices is more easily obtained by preventing the presence of a laser hot spot observed in front of the cornea in the absence of a scattering element. Diffuse laser illumination does not introduce any adverse effects on digitally computed laser Doppler images.Comment: 9 page

Une nouvelle méthode de décomposition polynomiale d’un front d’onde oculaire

The eye vision defaults are analyzed and classified by studyingthe corresponding eye wavefront. After presenting the orthogonal basis, called the Zernike basis, that is currently used for the medical diagnosis, a new decomposition basis is built. It is based on the use of the space of polynomials of valuation greater or equal to L+1 (for L a natural integer). It allows to uniquely decompose a polynomial wavefront into the sum of a polynomial of low degree (lesser or equal to L) and a polynomial of high valuation (greater or equal to L +1). By choosing L = 2, a new decomposition, called D2V3, is obtained where the polynomial wavefront of high degree does not include terms of radial degree lesser or equal to 2. In particular, it allows to quantify perfectly the aberrations that can be corrected by eyeglasses or not. Various clinical examples clearly show the interest of this new basis compared to a diagnosis based on the Zernike decomposition.Les défaut de la vision sont analysés et classés à partir des caractéristiques mathématiques du front d’onde de l’oeil considéré. Après avoir présenté la méthode actuelle basée sur la décomposition du front d’onde dans la base orthonormale de Zernike ainsi que certaines de ses limitations, on propose ici une nouvelle base de décomposition. Celle-ci repose sur l’utilisation del’espace des fronts d’onde polynomiaux de valuation supérieure ou égale à L + 1 (où L est un entier naturel) et permet de décomposer de manière unique un front d’onde polynomial en la somme d’un front d’onde polynomial de bas degré (inférieur ou égal à L) et un front d’onde polynomial de haute valuation (supérieure ou égal à L + 1). En choisissant L = 2, une nouvelle décomposition est obtenue, appelée D2V3, où le front d’onde polynomial de haut degré ne comporte pas de termes de degré radial inférieur ou égal à deux. Cette approche permet de dissocier parfaitement les aberrations optiques corrigibles ou non par le port de lunettes. Différents cas cliniques présentés dans la dernière section permettent de mettre en évidence l’intérêt de cette nouvelle base de décomposition

A new polynomial decomposition method for ocular wavefront

Les défaut de la vision sont analysés et classés à partir des caractéristiques mathématiques du front d’onde de l’oeil considéré. Après avoir présenté la méthode actuelle basée sur la décomposition du front d’onde dans la base orthonormale de Zernike ainsi que certaines de ses limitations, on propose ici une nouvelle base de décomposition. Celle-ci repose sur l’utilisation del’espace des fronts d’onde polynomiaux de valuation supérieure ou égale à L + 1 (où L est un entier naturel) et permet de décomposer de manière unique un front d’onde polynomial en la somme d’un front d’onde polynomial de bas degré (inférieur ou égal à L) et un front d’onde polynomial de haute valuation (supérieure ou égal à L + 1). En choisissant L = 2, une nouvelle décomposition est obtenue, appelée D2V3, où le front d’onde polynomial de haut degré ne comporte pas de termes de degré radial inférieur ou égal à deux. Cette approche permet de dissocier parfaitement les aberrations optiques corrigibles ou non par le port de lunettes. Différents cas cliniques présentés dans la dernière section permettent de mettre en évidence l’intérêt de cette nouvelle base de décomposition.The eye vision defaults are analyzed and classified by studyingthe corresponding eye wavefront. After presenting the orthogonal basis, called the Zernike basis, that is currently used for the medical diagnosis, a new decomposition basis is built. It is based on the use of the space of polynomials of valuation greater or equal to L+1 (for L a natural integer). It allows to uniquely decompose a polynomial wavefront into the sum of a polynomial of low degree (lesser or equal to L) and a polynomial of high valuation (greater or equal to L +1). By choosing L = 2, a new decomposition, called D2V3, is obtained where the polynomial wavefront of high degree does not include terms of radial degree lesser or equal to 2. In particular, it allows to quantify perfectly the aberrations that can be corrected by eyeglasses or not. Various clinical examples clearly show the interest of this new basis compared to a diagnosis based on the Zernike decomposition

Refractive and diffractive contribution of linear chromatic aberration (LCA) on depth-of-focus with trifocal intraocular lenses (IOLs)

Purpose: To investigate the refractive and diffractive contribution of LCA on depth of focus extension of trifocal IOLs in polychromatic light conditions Setting: University of Liège, Belgium; Fondation Ophtalmologique A. de Rothschild, Paris Methods: The LCAs associated with the three focal points of hydrophobic and hydrophilic diffractive FineVision trifocal IOLs (PhysIOL SA, Liège, Belgium), were simulated in an Arizona eye model and experimentally measured on an optical bench at 480, 546 and 650 nm. The effect of Abbe number and aperture on different IOL materials was also evaluated. Based on wavelength–dependent MTF through-focus curves and PSF properties, polychromatic behavior of the trifocal IOLs was assessed under mesopic and photopic conditions. Results: LCA amplitude and sign were different for each of the trifocal IOL focal points. The diffractive LCA for near and intermediate was independent of IOL material (GFree versus hydrophilic acrylic, 26%), while far vision LCA appeared to be controlled by the material Abbe number. Under polychromatic conditions, the LCA contributed to depth of focus extension with different types of lens material, providing maximal visual acuity under white light conditions at all distances. Conclusions: Diffractive trifocal IOLs show chromatic aberrations with an increase in depth of focus under polychromatic light. This effect likely contributes to the extended range of vision

A NEW TRIFOCAL DESIGN

Purpose: Contributions of IOL biomaterial (Abbe #) and diffractive pattern topography on LCA of various types of multifocal IOLs. Methods: The LCAs associated with the different focal points of diffractive hydrophobic – made of aromatic and/or aliphatic materials – and hydrophilic multifocal IOLs were experimentally determined on an optical bench in RGB conditions (650, 546 and 480 nm). The effects of Abbe number and of the topography of the different diffractive profiles were evaluated. Based on wavelength–dependent MTF through-focus curves, polychromatic behavior of multifocal IOLs was assessed. Results: LCA amplitudes and signs were different for each of the focal points. While far vision LCA was of negative sign and appeared to be controlled by the material Abbe number, the diffractive LCA for near and intermediate visions was independent of IOL material. The diffractive pattern characteristics, which control the closer distance powers, prove to be pivotal in fine-tuning the LCA related to these near and intermediate foci. Conclusions: Diffractive multifocal IOLs show chromatic aberrations with are controlled by the biomaterial Abbe number for its refractive component on the one hand, and by the topography of the diffractive pattern for the second component on the other hand