Tolerance to decentration of biaspheric intraocular lenses with refractive phase-ring extended depth of focus and diffractive trifocal designs.

PURPOSE: This study aimed to investigate the in vitro tolerance to decentration of biaspheric intraocular lens (IOLs) with refractive phase-ring extended depth-of-focus (EDOF) and diffractive trifocal designs. METHODS: This experimental study was carried out at the Department of Optics and Optometry and Vision Science, University of Valencia, Spain. The modulation transfer function (MTF) of the ETLIO130C EDOF and the TFLIO130C trifocal IOLs (AST Products Inc., Billerica, MA, USA) were determined at different levels of decentration for a given wavelength and pupil diameter using the PMTF optical bench (Lambda-X Ophthalmics, Nivelles, Belgium). The modulation transfer function (MTF) curves, the through-focus MTF curves, and the Strehl ratios were measured at 3-mm pupil aperture for 0.25-, 0.50- and 0.75-mm decentration. RESULTS: The optical design of the trifocal TFLIO130C IOL is robust to small decentrations, with virtually no change in MTF response for 0.25 mm decentration. For greater decentration levels, the MTF response is slightly reduced with increasing decentration. The ETLIO130C EDOF design is robust to decentration, as the MTF response is only minimally affected when increasing the decentration up to 0.75 mm. CONCLUSIONS: MTF responses are slightly reduced with greater levels of decentration, but the range of focus provided by both trifocal and EDOF designs are preserved. The effects for average levels of decentration reported in the literature are minimum for both IOL designs.

Blinking kinematics characterization during digital displays use.

PURPOSE: This study aimed to assess the differences in blinking kinematics while reading on different digital displays and a control condition. METHODS: Thirty-two young healthy individuals were included in this prospective clinical study. The blinks of subjects were recorded for 150 s while reading on a laptop computer, tablet, e-reader, and smartphone and a control condition. Blinks were recorded using an eye-tracking device and were analyzed by means of image analysis to obtain a non-invasive detailed description of the blink movement. RESULTS: Blink rate decreased when reading on all displays compared to the control (p < 0.0005), although no differences were obtained amongst displays (p > 0.05). The percentage of incomplete blinks was higher with the computer compared to the control (p = 0.043), and lower with the smartphone compared to the rest of the conditions (p ≤ 0.015). Blink amplitude was smaller when reading from handheld devices compared to the control (p < 0.0005) and the computer (p ≤ 0.048). Closing and opening blink durations remained unvaried amongst conditions (p > 0.05), while opening and closing speeds were greater for the control and the computer compared to the handheld displays (p < 0.0005). Finally, contact and total blink durations were shorter during computer reading compared to the control (p = 0.004 and p = 0.017, respectively). CONCLUSION: Blinking kinematics vary considerably amongst displays and with respect to baseline, with these differences being probably attributed to differences in the way the displays are set up and the cognitive demand of the task.

Power Profiles and In Vitro Optical Quality of Scleral Contact Lenses: Effect of the Aperture and Power.

OBJECTIVE: To assess the power profile and in vitro optical quality of scleral contact lenses with different powers as a function of the optical aperture. METHODS: The mini and semiscleral contact lenses (Procornea) were measured for five powers per design. The NIMO TR-1504 (Lambda-X) was used to assess the power profile and Zernike coefficients of each contact lens. Ten measurements per lens were taken at 3- and 6-mm apertures. Furthermore, the optical quality of each lens was described in Zernike coefficients, modulation transfer function, and point spread function (PSF). A convolution of each lens PSF with an eye-chart image was also computed. RESULTS: The optical power fluctuated less than 0.5 diopters (D) along the optical zone of each lens. However, the optical power obtained for some lenses did not match with its corresponding nominal one, the maximum difference being 0.5 D. In optical quality, small differences were obtained among all lenses within the same design. Although significant differences were obtained among lenses (P<0.05), these showed small impact in the image quality of each convolution. CONCLUSIONS: Insignificant power fluctuations were obtained along the optical zone measured for each scleral lens. Additionally, the optical quality of both lenses has showed to be independent of the lens power within the same aperture.

Comparison of the influence of corneo-scleral and scleral lenses on ocular surface and tear film metrics in a presbyopic population.

PURPOSE: To assess and compare the effect of the corneo-scleral lenses (C-ScL) and scleral lenses (ScL) on tear film parameters and central corneal thickness (CCT) in healthy presbyopic subjects. METHODS: Thirty subjects wore two contact lenses (CLs), randomly assigned, of neutral power, but of different diameters, 12.7mm (C-ScL) and 18mm (ScL) and being equal in the others parameters: material (HS100) and centre thickness (0.29mm). At baseline, 20min after insertion and at 8h, the tear meniscus area (TMA) and CCT was measured (with optical coherence tomography) as well as tear osmolarity. RESULTS: TMA revealed statistical differences for both lenses at 20min (p<0.001), and also at 8h (p=0.003), being greater for the C-ScL. CCT showed statistical differences for both lenses at 20min (p=0.002), and also at 8h (p=0.001), being lower for the C-ScL. Osmolarity did not reveal statistical differences at 20min (p=0.29), while it was statistically different at 8h (p=0.03), being lower for the C-ScL. CONCLUSIONS: C-ScL lead to a lesser reduction in the TMA and a lower induced hypoxic stress than the ScL. Osmolarity levels remained within normal values across the day with no clinical difference between lenses. Both designs can represent a good optical platform for correcting presbyopia as well as protecting the ocular surface by vaulting the cornea.

Posterior chamber phakic intraocular lenses to improve visual outcomes in keratoconus patients.

The aim of this review is to summarize the results of using posterior chamber phakic intraocular lenses (pIOLs) to restore quality of vision in keratoconus patients. These pIOLs can correct the refractive errors associated with keratoconus and can also be combined with other surgical techniques to improve the results.

Accommodation in human eye models: a comparison between the optical designs of Navarro, Arizona and Liou-Brennan.

AIM: To simulate and compare accommodation in accommodative and non-accommodative human eye models. METHODS: Ray tracing and optical design program was used. Three eye models were designed and studied: the Navarro, the Arizona and the Liou-Brennan. In order to make the Navarro and Liou-Brennan models to accommodate, specific geometric parameters of the models were altered with values that were chosen from the literature. For the Arizona model, its' mathematical functions for accommodation were used for the same accommodative demands. The simulation included four distances of accommodation for each model: at infinity, 3, 1 and 0.5 m.The results were diffraction images of a "letter F" for graphical comparison, spot diagrams on the retinal field and Modulation Transfer Function (MTF) graphs. RESULTS: Zernike coefficients for the aberrations, Airy disk diameter, root mean square (RMS) error diameter and total axial length of the model were provided from the program. These were compared between them in all distances. The Navarro model had the smallest axial length change as a simple model. The Arizona did not change its axial length because it is designed to be accommodative. The Liou-Brennan model had different results concerning the aberrations because of the decentration of the pupil. The MTF graphs showed small differences between the models because of the differences in their designs. CONCLUSION: All the three models are able to simulate accommodation with the expected results. There is no model that can be assumed as the best choice. Accommodation can be simulated in non-accommodativemodels and in customized ones.

In vitro optical quality comparison of 2 trifocal intraocular lenses and 1 progressive multifocal intraocular lens.

PURPOSE: To evaluate the optical quality of 3 multifocal intraocular lenses (IOLs): the Mini Well Ready progressive multifocal aspheric IOL, the AT LISA trifocal diffractive IOL, and the Finevision full diffractive trifocal IOL. SETTING: University of Valencia, Valencia, Spain. DESIGN: Experimental study. METHODS: An instrument designed for measuring real-time modulation transfer function (MTF) and IOL power was used to measure the optical quality of each IOL for 3.0 mm and 4.5 mm apertures. This instrument measures both sagittal and tangential MTFs. The optical quality of each IOL was evaluated with the MTF, through-focus MTF, defocus tolerance, Strehl ratio MTF, and relative percentage of light in each focus. These metrics were evaluated at best focus for each IOL. RESULTS: Through-focus graphs corresponding to trifocal IOLs showed 3 mean peaks. Nevertheless, the progressive multifocal aspheric IOL showed 2 main areas, 1 corresponding to distance vision focus and the other including both intermediate and near vision foci. CONCLUSIONS: The results obtained in the present study suggest that the progressive multifocal aspheric IOL might be considered for cataract surgery. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any method or material mentioned.

Optical quality comparison among different Boston contact lens materials.

BACKGROUND: The aim was to assess the optical quality of four Boston contact lens materials with an optical device based on Schlieren interferometry. METHODS: The NIMO TR1504 (Lambda-X, Nivelles, Belgium) was used to measure higher-order aberrations and their corresponding root mean square values of four different rigid gas permeable contact lenses made from four different Boston materials: EO, ES, XO and XO2 . For each lens, 30 measurements were performed with two optical apertures: 3.0 mm and 6.0 mm. The modulation transfer function, point spread function, Strehl ratio and a simulation of the image provided by the lens were computed from the Zernike coefficients measured up to the fourth order. RESULTS: The root mean square error of higher-order aberrations varied significantly with material type for both optical apertures (p < 0.01). The largest difference was obtained between the Boston EO and the Boston ES materials (for a 6.0 mm aperture), the mean difference being (8.3 ± 0.2) × 10(-2) µm. The modulation transfer functions, point spread functions and Strehl ratio values were similar among all Boston materials at the smaller optical aperture; however, differences between each material were more apparent for the 6.0 mm aperture, with the Boston ES material exhibiting the best optical quality. CONCLUSIONS: In terms of all metrics analysed, all Boston materials examined showed comparable optical quality for a 3.0 mm aperture but the Boston ES material displayed the best optical quality for a 6.0 mm optical aperture.

In vitro optical quality comparison between the Mini WELL Ready progressive multifocal and the TECNIS Symfony.

PURPOSE: To compare the optical quality between two intraocular lenses (IOLs): the Mini WELL Ready progressive multifocal (SIFI Medtech, Catania, Italy), and the TECNIS Symfony (Abbott Laboratories, Illinois, USA), which both provide a continuous range of vision from far to near positions. METHODS: The in vitro optical quality of each lens was assessed with an instrument conceived for measuring the modulation transfer function (MTF). The optical quality of each lens was described in terms of MTF, through-focus MTF, defocus tolerance, pupil dependence, and Strehl ratio MTF. These metrics were assessed for the best lens far focus, and at four vergences (from -1.5 to -3.0 D in 0.5-D steps), at 3.0 and 4.5 mm apertures. RESULTS: The through-focus curves of each lens showed two main areas: one corresponding to far-distance vision, and another to intermediate- and near-distance vision. Both lenses showed similar MTF curves and Strehl ratio values at both apertures. The optical quality of both lenses slightly decreased with the aperture for all vergences. Nevertheless, the quality of the progressive multifocal lens increased with the aperture at far-distance vision. This lens also showed the largest defocus tolerance at near-distance vision for both apertures. CONCLUSIONS: The results obtained in the present study suggest that both designs might enlarge the depth of focus. Whereas, the Mini WELL Ready showed better optical quality than the TECNIS Symfony at far vision with 4.5 mm aperture, and larger defocus tolerance than the diffractive lens at near-distance vision.

Effect of Large Apertures on the Optical Quality of Three Multifocal Lenses.

PURPOSE: To compare the optical quality under large apertures among three multifocal intraocular lenses (IOLs): the TECNIS Symfony ZXR00 (Abbott Laboratories, Abbott Park, IL), the AT LISA tri 839MP (Carl Zeiss Meditec, Jena, Germany), and the Finevision (PhysIOL, Liège, Belgium). METHODS: The in vitro optical quality of each lens was assessed with an instrument that measured the modulation transfer function (MTF). The optical quality of each lens was described in terms of MTF and through focus average MTF. The Strehl ratio, cut-off frequency, area of visibility, and percentage energy were calculated to objectively describe the optical quality of each lens. These metrics were assessed for the best lens distance focus and at four vergences (from -1.50 to -3.00 D in 0.50-D steps) at a 4.5-mm aperture. RESULTS: The through focus average MTF of the AT LISA and Finevision IOLs showed three mean areas corresponding to distance, intermediate, and near vision. The TECNIS Symfony IOL showed two main areas corresponding to distance and intermediate vision. All metrics revealed that the Finevision IOL showed the best optical quality at distance vision, the TECNIS Symfony IOL at intermediate vision, and the AT LISA IOL at near vision. The TECNIS Symfony IOL showed the most homogeneous light distribution between its best vision foci. CONCLUSIONS: The TECNIS Symfony IOL is less vergence dependent than the AT LISA and Finevision IOLs under dim conditions. These results may help clinicians to choose the proper lens depending on the patient's visual requirements.

Repeatability of in vitro power profile measurements for multifocal contact lenses.

PURPOSE: To evaluate the repeatability of an optical device (NIMO TR1504, Lambda-X, Belgium) for measuring multifocal contact lens power profiles. METHODS: The NIMO TR1504 was used to measure power profiles 30 times for each of 10 different contact lenses from 4 major companies. All contact lenses were labelled as -3D for distance vision; half were for high addition and half for low addition. The optical zone in all measurements was set to 3-mm radius. For each lens, the median power profile and the residuals of the 30 measurements were calculated. The 95% confidence bands and two indices that summarize measurement errors were calculated: the repeatability limit and an index of repeatability heterogeneity, quantifying heterogeneity of measurement errors over the optical zone. RESULTS: The repeatability limit was good (from 0.04D to 0.12D), for all multifocal contact lenses. Variability of measurement errors of power profiles was quite homogeneous along the optical zone for all lenses, although for some lenses variability was slightly higher in the centre than peripherally. CONCLUSIONS: The repeatability of measured power profiles obtained by the NIMO TR1504 is lower than 0.12D for the multifocal contact lenses.