Search

The optical quality of three multifocal intraocular lenses (MIOLs) was measured in vitro using the area under the modulation transfer function (MTFa) and energy efficiency (EE). We evaluated those metrics through-focus (TF) by axially scanning the image space with three wavelengths (R, G, B). High linear correlation between MTFa and EE was found for all cases. Correlations between optical in vitro results (polychromatic TF-MTFa and TF-EE) and clinical visual acuity (VA) defocus curves for the three MIOLs allowed us to derive mathematical expressions. Both metrics proved to be equivalent to predict postoperative VA.

Purpose: To assess the power profile and optical performance of 2 extended range-of-vision (ERV) intraocular lenses (IOLs), TECNIS Eyhance (ICB00) and LuxSmart, and compare them with their monofocal counterpart lenses with similar platforms and materials: TECNIS 1-piece (ZCB00) and LuxGood, respectively. Setting: Optics and Optometry Faculties of Complutense University (Madrid) and Universitat Politècnica de Catalunya Barcelona-Tech (Terrassa) in Spain. Design: Laboratory investigation on optical bench. Methods: For each design, the power distribution and (fourth and sixth-order) spherical aberration (SA) across the lens aperture were measured as well as the optical performance using modulation transfer function-based metrics with through-focus evaluation. 3 nominal powers (+10.00 diopters [D], +20.00 D, and +30.00 D) and 3 pupil sizes (2.0 mm, 3.0 mm, and 4.5 mm) were considered to assess whether the base power of the lens and pupillary dynamics have an influence on the depth-of-focus extension. Results: TECNIS Eyhance and LuxSmart IOLs had different power and SA profiles, but both designs shared a positive add power in their central region in comparison with their monofocal counterparts. LuxSmart had a greater add power while TECNIS Eyhance showed higher peak optical quality but smaller depth of focus. Conclusions: Differences of focus extension between the 2 ERV IOL designs are related to differences of power and SA profile. The nominal base power of the IOLs has little effect on their optical quality. However, pupil dynamics plays a key role since it determines the effective add power and optical performance of the ERV IOLs. [ABSTRACT FROM AUTHOR]

The influence of astigmatism on the image formed by a model eye with an intraocular lens (IOL) inserted is analysed. Toric (T-) and non-toric (N-) versions of the same monofocal spherical aberration-free IOL (20 D) were considered, for a range of uncorrected astigmatism from 0.0 to 2.0 D, and two pupils (3.0, 4.5 mm). With the T-IOL, the effect of a rotation error up to 35° was also investigated. An adaptive optics system was used to either compensate or introduce computer- controlled astigmatism. The optical quality was tested by evaluating the modulation transfer function integrated in a range of spatial frequencies from 0 to 50 c/mm in a through-focus analysis. Uncorrected astigmatism degraded the quality of the optical image in the spherical equivalent plane to a similar extent for both IOLs. A model eye with an astigmatism-free cornea plus the N-IOL provided the best image for plane wave illumination. With the T-IOL (1.25 D cyl) the best image was obtained after inducing corneal astigmatism of 0.9D to compensate for the 1.25D cylinder at the IOL plane. A rotation error between the astigmatism axes of the cornea and the T-IOL produced undesired residual astigmatism with an axis direction change. A rotation error up to 10° caused low image degradation. [ABSTRACT FROM AUTHOR]

It is important to distinguish between visual acuity, optical quality and quality of vision when outcomes obtained with intraocular lenses are evaluated. These parameters, that includeobjective and subjective tests, should be assessed to obtain results that are not biased. To assess the difference in visual and optical quality between two monofocal intraocular lens models. : This was a prospective, parallel and randomised clinical study conducted at Miranza IOA, a private clinic in Madrid, Spain. Sixty patients were implanted bilaterally, 30 per group, with two aspheric IOLs with induced spherical aberration of −0.27 μm for Group A and −0.20 μm for Group B. Visual outcomes obtained at 1 and 3 months after surgery included both uncorrected (UCVA) and corrected monocular distance visual acuity (DCVA), objective scattering index (OSI), modulation transfer function (MTF) cut-off, Strehl Ratio (SR), contrast sensitivity defocus curve (CSDC), intraocular lens spherical aberration (SA), and longitudinal chromatic aberration of the eye. Activity limitations in daily life were assessed using CatQuest-9SF questionnaire. There were statistically significant differences for DCVA (0.04 LogMAR; p =.008) and SR (0.03; p =.003) between groups. Outcomes related to CSDC showed statistically significant differences for vergences between −0.50 D and +1.00 D (3 mm pupil) and for vergences of 0.00 D and +0.50 D (4.5 mm pupil) between groups. Overall, Group A showed better results regarding visual and optical quality, including a lower longitudinal chromatic aberration result in comparison to Group B. Patient satisfaction evaluated with CatQuest-9SF showed that Group A achieved better outcomes, although the differences were statistically significant only for the 'Reading text on television' item (p = 0.027). Both intraocular lens models showed excellent quantity of vision, optical and visual quality as well as high patient satisfaction. Despite this, the the Group A model provided slightly better outcomes than the Group B model. [ABSTRACT FROM AUTHOR]

An analysis is given of how nonuniformities in the laser beam intensity translate into variations on the induced temperature distribution on an irradiated sample. The study involves materials with different thermal conductivities. By use of a reshaped irradiating beam obtained with a multifaceted integrating mirror, a three-dimensional numerical calculation allows us to establish both surface and in-depth temperature distributions. The results show that in the case of materials such as glass (i.e., with low thermal conductivity) large thermal gradients occur both on the surface and in depth during irradiation. However, the lateral heat flow is high enough to strongly reduce the surface gradients as soon as the laser irradiation ends. Conversely, in good thermal conductors such as nickel, the laser intensity nonuniformities induce a thermal peaking of the surface with lateral thermal gradients that are by no means negligible. Experimental evidence during laser glass polishing that confirms the numerical assessments are also provided.

Compare subjective (Rx) and objective (ObjRx) refractions outcomes with two autorefractors models and an aberrometer in eyes implanted with a hydrophobic trifocal IOL (FineVision POD F GF, Physiol, Liége, Belgium) and a hydrophilic one (FineVision POD F, Physiol, Liége, Belgium). Prospective comparative cohort study, with 100 subjects randomly assigned to either the POD F group (n = 50) or the POD F-GF group (n = 50). Postoperative eye examinations at 1-month visit included seven result sets, one for each assessment method: Rx, AR (automated refraction measured with the autorefractor KR8800), WF-P (Zernike-coefficients-based objective refraction, photopic pupil size), WF-M (Zernike-coefficients-based objective refraction, mesopic pupil size), WF-4 (Zernike-coefficients-based objective refraction, 4 mm pupil), OPD-C (automated refraction measured with the aberrometer OPD in the central pupil/photopic conditions), and OPD-M (automated refraction measured with the aberrometer OPD under mesopic conditions). Mean differences between ObjRx and Rx reached statistical significance for sphere and spherical equivalent (M) only with OPD-C in the POD F-GF group. All ObjRx methods showed significant differences with Rx in the POD F group, with some values differing by more than 0.50 D (−0.58 D in M for the WF-P). Bland Altman plots showed better agreement for the astigmatic components, and for sphere and spherical equivalents in both IOL groups measured with AR and OPD-M. None of the objective methods of refraction evaluated in this study were as reliable as the subjective refraction, irrespective of the lens material, but POD F-GF ObjRx seems to differ less with Rx than POD F ObjRx values. [ABSTRACT FROM AUTHOR]

This work reports on the fabrication of 1D fringed patterns on nanostructured porous silicon (nanoPS) layers (563, 372, and 290 nm thick). The patterns are fabricated by phase-mask laser interference using single pulses of an UV excimer laser (193 nm, 20 ns pulse duration). The method is a single-step and flexible approach to produce a large variety of patterns formed by alternate regions of almost untransformed nanoPS and regions where its surface has melted and transformed into Si nanoparticles (NPs). The role of laser fluence (5-80 mJ cm-2), and pattern period (6.3-16 μm) on pattern features and surface structuring are discussed. The results show that the diameter of Si NPs increases with fluence up to a saturation value of 75 nm for a fluence ≈40mJcm-2. In addition, the percentage of transformed to non-transformed region normalized to the pattern period follows similar fluence dependence regardless the period and thus becomes an excellent control parameter. This dependence is fitted within a thermal model that allows for predicting the in-depth profile of the pattern. The model assumes that transformation occurs whenever the laser-induced temperature increase reaches the melting temperature of nanoPS that has been found to be 0.7 of that of crystalline silicon for a porosity of around 79%. The role of thermal gradients across the pattern is discussed in the light of the experimental results and the calculated temperature profiles, and shows that the contribution of lateral thermal flow to melting is not significant for pattern periods ≥6.3 μm. [ABSTRACT FROM AUTHOR]