Ocular biometric changes with different accommodative stimuli using swept-source optical coherence tomography.

PURPOSE: To evaluate ocular biometric changes with different accommodative stimuli using a new swept-source optical biometer. METHODS: Only the right eye was analyzed. Each subject was measured six times with the IOLMaster 700 swept-source optical biometer (Carl Zeiss Meditec, Jena, Germany) with the subject looking at the stimulus shown by the instrument and with the subject looking at a target placed outside the instrument at 0D of vergence. Axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), lens thickness (LT), white-to-white (WTW), and keratometry readings (K1 and K2) were evaluated in both cases. To assess if the changes found may affect the intraocular (IOL) power calculation for surgical applications, we have applied some formulae, using the software provided by the optical biometer manufacturer, to the ocular parameters found in both situations for three different types of IOLs. RESULTS: No statistically significant differences were found for AL, CCT, WTW, K1 and K2 between the subject looking at the stimulus of the biometer and looking at the outside target at 0D of vergence (p > 0.05). However, the measurement of ACD revealed a statistically significant reduction of 20 microns (p = 0.03) and, on the contrary, LT increased significantly 30 microns (p = 0.02). ACD and LT changes were highly correlated (R2 = 0.91). As for the IOL power calculation, in all cases, the mean change was lower than 0.25 D both for IOL power selection and residual refraction. CONCLUSIONS: Although ACD and LT change significantly with different accommodative stimuli measured by swept-source optical biometry, these changes are not clinically relevant.

Accommodative stimulus-response curves to low-pass filtered natural images.

PURPOSE: To assess how the monocular steady-state accommodative stimulus-response curve is modified when viewing low-pass filtered natural images. METHODS: Eighteen adult subjects participated in the study. The accommodative stimulus-response curve was objectively assessed by means of a Hartmann-Shack wavefront sensor. Measurements were taken at different accommodative demands. Target images were low-pass filtered versions of a natural image that were obtained applying different digital spatial filters that limited the spatial frequency content of the natural image. Cutoff spatial frequencies were set at 30, 21, and 15 cycles per degree (cy/deg). RESULTS: Mean data obtained for each target were fitted to linear models. For the low-pass filtered natural image with a cutoff spatial frequency at 30 cy/deg, the slope for the averaged stimulus-response curve was 0.614, while the slopes obtained for the other two low-pass filtered images corresponding to cutoff frequencies at 21 and 15 cy/deg were 0.613 and 0.619, respectively (p < 0.01). The determination coefficient was R2 ≥ 0.988 for all targets. An ANCOVA analysis revealed that these slopes were not significantly different from each other (p = 0.82). Additionally, accommodative error indexes were obtained to measure both the discrepancy between the regression lines and the ideal lines and the degree of correlation between the stimulus and the response. CONCLUSIONS: Our study reveals that the low and middle spatial frequencies (< 15 cy/deg) are the most important to guide to the needed levels the accommodative response to natural images.

In vitro optical quality of monofocal aspheric toric intraocular lenses: effect of cylindrical power.

PURPOSE: To assess the in vitro optical quality of monofocal aspheric toric intraocular lenses (IOLs) as a function of the cylindrical power. METHODS: The in vitro optical quality of the AcrySof IQ Toric IOLs SN6AT2, SN6AT3, SN6AT4, SN6AT5 and SN6AT6 (Alcon Laboratories Inc., Forth Worth, TX, USA) was assessed with an instrument conceived for measuring Zernike's coefficients at 3.0- and 5.0-mm apertures. As a reference, the aspheric monofocal lens AcrySof IQ Aspheric SN60WF (Alcon Laboratories Inc., Forth Worth, TX, USA) was also measured. The area of visibility and cut-off frequency were used to describe the modulation transfer function (MTF) of each lens; meanwhile, the light in the bucket and the diameter of a circular area centred on the point-spread function (PSF) peak that captures 50% of the light energy were used to describe the PSF of each lens. Finally, an image simulation was computed from the Zernike values with reference purposes. RESULTS: Small differences were found on the metrics used for describing the MTF and PSF of the lenses at both tested apertures, but these were not statistically significant (p > 0.05). Furthermore, the image simulation showed that these differences would not have clinical relevance at all. CONCLUSIONS: The optical performance of the AcrySof IQ toric IOLs in terms of MTF and PSF is good and seems to be independent of the cylindrical power and similar to a non-toric aspheric lens.

Evaluation of the repeatability of a swept-source ocular biometer for measuring ocular biometric parameters.

PURPOSE: The purpose was to evaluate the repeatability of a new swept-source optical biometer for measuring ocular biometric parameters. METHODS: Thirty subjects with healthy and phakic eyes were included in this study, and only one eye per participant was analysed. Each eye was measured five times with the IOLMaster 700 swept-source optical biometer (Carl Zeiss Meditec, Jena, Germany). Axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT), lens thickness (LT), white-to-white (WTW), and K1 and K2 keratometric readings were evaluated. The repeatability of swept-source biometry was evaluated on the basis of five measurements captured for each patient. RESULTS: The repeatability limits for the axial measurements AL, ACD, CCT, and LT were 0.03, 0.07, 0.004, and 0.11 mm, respectively. For the WTW distance and both keratometry readings, the repeatability limits were 0.20, 0.06, and 0.05 mm, respectively. The AL resulted in the lowest coefficient of variation, and the LT had the highest one. The spherical equivalent showed statistically significant negative correlations with the AL and ACD. CONCLUSION: Swept-source optical biometry showed high repeatability performance for all biometric parameters in healthy eyes, where the correlation between the spherical equivalent and AL showed the strongest value.

Ocular anatomic changes for different accommodative demands using swept-source optical coherence tomography: a pilot study.

PURPOSE: The purpose of our study was to assess the changes in ocular parameters for different accommodative demands using a new optical biometer based on swept-source optical coherence tomography (SS-OCT). METHODS: Seven subjects were included in this pilot study, and only one eye per participant was analyzed. Each eye was measured six times with the optical biometer IOLMaster 700 (Carl Zeiss Meditec, Jena, Germany). As this instrument is not able to change the vergence of the stimulus, to enable measurements at different accommodative states, a tilted first-surface mirror attached to the optical biometer was used to place the fixation stimulus at different vergences. Measurements were taken on the right eye of the subject while the left eye was looking through the mirror. Central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), axial length (AL), white-to-white (WTW) distance and keratometric readings were evaluated for three different accommodative states: 0.0 diopters (D), 1.5 D, and 3.0 D. RESULTS: No statistically significant differences were found for CCT, AL, WTW, K1 and K2 between the three accommodative states. As expected, changing the accommodative condition did not change CCT, AL, WTW, and keratometric outcomes. Nevertheless, statistically significant differences between the accommodative states were found for ACD and LT measurements. In addition, variations in ACD correlated linearly with variations in LT (R2 ≥ 0.99) when changing the vergence of the optotype. CONCLUSION: A practical methodology to assess the changes in ocular parameters for different accommodative demands using the IOLMaster 700 based on SS-OCT has been described. Statistically significant changes that have been found that agree well with previous reports.

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.

Visual performance of four simultaneous-image multifocal contact lenses under dim and glare conditions.

OBJECTIVE: To assess and compare the effects of four simultaneous-image multifocal contact lenses (SIMCLs), and those with distant-vision-only contact lenses on visual performance in early presbyopes, under dim conditions, including the effects of induced glare. METHODS: In this double-masked crossover study design, 28 presbyopic subjects aged 40 to 46 years were included. All participants were fitted with the four different SIMCLs (Air Optix Aqua Multifocal [AOAM; Alcon], PureVision Multifocal [PM; Bausch & Lomb], Acuvue Oasys for Presbyopia [AOP; Johnson & Johnson Vision], and Biofinity Multifocal [BM; CooperVision]) and with monofocal contact lenses (Air Optix Aqua, Alcon). After 1 month of daily contact lens wearing, each subject's binocular distance visual acuity (BDVA) and binocular distance contrast sensitivity (BDCS) were measured using the Functional Visual Analyzer (Stereo Optical Co., Inc.) under mesopic conditions (3 candela [cd]/m) both with no glare and under the 2 levels of induced glare: 1.0 lux (glare 1) and 28 lux (glare 2). RESULTS: Among the SIMCLs, in terms of BDVA, AOAM and PM outperformed BM and AOP. All contact lenses performed better at level without glare, followed by Glare 1, and with the worst results obtained under glare 2. Binocular distance contrast sensitivity revealed statistically significant differences for 12 cycles per degree (cpd). Among the SIMCLs, post hoc multiple comparison testing revealed that AOAM and PM provided the best BDCS at the three luminance levels. In both cases, BDVA and BDCS at 12 cpd, monofocal contact lenses outperformed all SIMCL ones at all lighting conditions. CONCLUSIONS: Air Optix Aqua Multifocal and PM provided better visual performance than BM and AOP for distance vision with low addition and under dim conditions, but they all provide worse performance than monofocal contact lenses.

Measurement of angle Kappa with Orbscan II and Galilei G4: effect of accommodation.

PURPOSE: To measure angle kappa distance with Orbscan II and Galilei G4, and to evaluate possible variations in this value for different accommodation degrees. METHODS: Angle kappa was measured using the Orbscan II and the Galilei G4 in the right eye of 80 patients aged from 20 to 40 years. This value was measured three times per eye and per device, and the average was retained. Angle kappa was measured for far vision using the Orbscan II and the Galilei G4 in a random order for each subject. The Galilei G4 was used to measure angle kappa as a function of accommodation, where the first measure started at +1 D and the vergence was changed until reaching -4 D, in 1 D steps. In both measures, the kappa distance was expressed in millimetres. RESULTS: At distance, the values of angle kappa were 0.43 ± 0.13 mm and 0.27 ± 0.15 mm measured with the Orbscan II and Galilei G4 systems respectively. Statistical significant differences were found (P < 0.01). With regard to the angle kappa values obtained as a function of accommodation, the values were 0.25 ± 0.15 mm, 0.26 ± 0.15 mm, 0.30 ± 0.20 mm, 0.27 ± 0.15 and 0.26 ± 0.15 mm, for +1 D, -1 D, -2 D, -3 D and -4 D respectively. No statistical significant differences were found among 0 D and the other vergences evaluated (P > 0.01). CONCLUSIONS: For far vision, Orbscan II measured significantly higher angle kappa values than Galilei G4, the mean difference being 0.16 ± 0.08 mm. For different accommodation levels, the kappa distance did not change significantly.

Optical quality of aspheric toric intraocular lenses at different degrees of decentering.

PURPOSE: To analyze the optical quality of aspheric toric intraocular lenses (IOLs) at different degrees of decentering. METHODS: Wavefront aberrations of Acrysof IQ Toric IOLs (SN6AT3, SN6AT4, and SN6AT5; Alcon Laboratories Inc, Fort Worth, TX, USA) for different powers (15.00, 20.00 and 23.50 diopters [D]) and for different degrees of decentering (diagonal, horizontal, and vertical decentering of 0.3 and 0.6mm) were measured in vitro at 3- and 5-mm pupils. The Zernike coefficients of trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. The point spread functions (PSFs) and modulation transfer function (MTF) of each IOL evaluated were calculated from the wavefront aberrations. RESULTS: Coma aberration increased significantly with IOL decentration. Statistically significant differences were found between centered and all decentered positions in coma aberration (p < 0.05). Although, we only found visible differences between centered and decentered positions in PSF images and MTF curves for horizontal and vertical 0.6 mm of decentering at 3- and 5-mm pupil. CONCLUSIONS: Despite the coma increment, these values were clinically negligible and have no effect on visual performance, except for vertical and horizontal 0.6 mm of decentering, which could have a negative effect on visual quality.

Optical performance of two new trifocal intraocular lenses: through-focus modulation transfer function and influence of pupil size.

BACKGROUND: To compare the in vitro optical quality of two new trifocal intraocular lenses at different focal points as a function of pupil size. METHODS: Two intraocular lenses having different design approaches were evaluated: the AT LISA tri 839MP with a trifocal diffractive design, and the FineVision, which combines two distinct apodized bifocal diffractive profiles resulting in three foci. A PMTF optical bench was used to assess the intraocular lenses' performance, and as optical quality metrics, the through-focus modulation transfer function was selected; that is, it was measured at 10 focal points and for four different apertures (2.0, 3.0, 3.75 and 4.5 mm). RESULTS: For both lenses, the through-focus curve showed three peaks, corresponding to far, intermediate and near focal point. At the 0.0 D focal point, the FineVision yielded better results for larger pupils. At the -1.5 D focal point, both lenses performed worse for larger pupils. At the -3.0 D, the FineVision provided better results for all apertures. However, at the -3.5 D focal point, it was the AT LISA tri 839MP that outperformed the FineVision for larger pupils. CONCLUSIONS: The two trifocal intraocular lenses under analysis have modulation transfer function peaks that correspond to the far, intermediate and near focal points. For larger pupil sizes, the FineVision seems to provide better results at far focal points, while the AT LISA tri 839MP not only provides better results at the intermediate and near focal points, but is also less pupil size-dependent.

Optical quality differences between three multifocal intraocular lenses: bifocal low add, bifocal moderate add, and trifocal.

PURPOSE: To compare the in vitro optical quality at different focal points of two new bifocal intraocular lenses (IOLs) and one new trifocal IOL. METHODS: The AcrySof ReSTOR SV25T0 (+2.5 diopter [D] add) and the AcrySof ReSTOR SN6AD1 (+3.0 D add) with two main foci (Alcon Laboratories, Fort Worth, TX) and the AT LISA tri 839MP with three main foci (Carl Zeiss Meditec, Dublin, CA) were evaluated. The optical quality of the IOLs was measured with the PMTF optical bench (LAMBDA-X, Nivelles, Belgium). The optical quality of the IOLs was quantified by the modulation transfer function (MTF) at five different focal points (0.0, -1.5, -2.0, -2.5, and -3.0 D) and for 3.0- and 4.5-mm apertures. The through-focus MTF of the IOLs was also recorded. RESULTS: For the 0.0 D focal point, the AcrySof ReSTOR (+2.5 D add) obtained the highest MTF values for all apertures. For the -2.5 D focal point, the AcrySof ReSTOR (+3.0 D add) showed the highest MTF values for 3.0 mm. For the -3.0 D focal point at 3.0- and 4.5-mm aperture, the best values were obtained with the AcrySof ReSTOR (+3.0 D add) and the AT LISA, respectively. For the -1.5 D focal point, the trifocal IOL provided better values. For the -2.0 D focal point, all IOLs provided comparable results. The through-focus MTF curves showed three and two peaks for the trifocal and bifocal IOLs, respectively. CONCLUSIONS: The trifocal IOL provides a better optical quality at the -1.5 D focal point. However, the optical quality of the trifocal IOL significantly decreases compared to the bifocal IOLs at far distance and -2.5 D focal points.

Intra-eye visual function comparison with and without a central hole contact lens-based system: potential applications to ICL design.

PURPOSE: To evaluate the effects of a central hole contact lens-based design on visual performance and to compare it with the standard version of that same contact lens without the hole (non-hole scenario). METHODS: The visual performance of 10 myopic patients wearing either a central hole myopic contact lens or its corresponding standard version (non-hole contact lens) was assessed on the same eye. Monocular corrected distance visual acuity was measured under photopic conditions and monocular contrast sensitivity was measured under both photopic and mesopic conditions and higher-order ocular aberrations using Hartmann-Shack aberrometry. An in vitro optical analysis of both contact lenses was performed and a symptoms questionnaire was administered to the participants. RESULTS: No statistically significant differences in terms of corrected distance visual acuity were found: -0.091 and -0.098 logMAR for the hole and non-hole contact lenses, respectively (P > .05). Contrast sensitivity was comparable between lenses and no differences were found for specific spatial frequencies or a particular luminance level (P > .05). The hole contact lenses provided excellent outcomes, essentially equivalent to those of non-hole contact lenses, even in terms of subjective symptoms such as glare or halo. In vivo and in vitro optical quality analysis revealed no statistically significant differences between the hole and the non-hole contact lenses for either pupil size (P > .1). CONCLUSION: A contact lens having a central hole provides good visual and optical quality outcomes comparable to those yielded by the same lens without a hole. The results suggest that the impact of a central hole may be clinically negligible.

Optical quality of the Visian Implantable Collamer Lens for different refractive powers.

PURPOSE: To evaluate the optical quality of the Visian Implantable Collamer Lens (ICL) for different powers and pupil diameters. METHODS: Wavefront aberrations of the -3, -6, -9, -12 and -15 diopters (D) V4b ICLs were measured at 3- and 4.5-mm pupils. The root mean square (RMS) of total higher order aberrations (HOAs), trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration were evaluated. In addition, modulation transfer function (MTF) of the five ICL powers was measured for a 3-mm pupil. The point spread functions (PSFs) of each ICL evaluated was calculated from the wavefront aberrations at 4.5-mm pupil. RESULTS: The ICLs evaluated had negative spherical aberration and negligible amounts of other aberrations. The negative spherical aberration increases when the ICL power increases being related with its innate optical properties. At 3-mm pupil, no statistically significant differences between ICLs were found for all the Zernike coefficient RMS values analyzed (p > 0.05). At 4.5-mm pupil, significant RMS values for the spherical aberration and total HOAs were found between medium-low and high powers (p < 0.05). Similar MTFs were obtained for all ICLs, although they slightly worsened when increased the ICL power. CONCLUSIONS: ICLs evaluated provide good optical quality in terms of wavefront aberrations, MTF, and PSF. Although spherical aberration increases with ICL power, these values are clinically negligible to affect the visual quality after its implantation.

Crystalens HD intraocular lens analysis using an adaptive optics visual simulator.

PURPOSE: To compare visual and optical quality of the Crystalens HD intraocular lens (IOL) with that of a monofocal IOL. METHODS: The wavefront aberration patterns of the monocular Akreos Adapt AO IOL and the single-optic accommodating Crystalens HD IOL were measured in a model eye. The Crystalens IOL was measured in its nonaccommodative state and then, after flexing the haptic to produce 1.4 mm of movement, in its accommodative state. Using an adaptive optics system, subjects' aberrations were removed and replaced with those of pseudophakes viewing with either lens. Monocular distance visual acuity (DVA) at high (100%), medium (50%), and low (10%) contrast and contrast sensitivity (CS) were measured for both IOL optics. Near VA (NVA) and CS were measured for the Crystalens HD IOL in its accommodative state. Depth of focus around the distance and near focus was also evaluated for the Crystalens HD IOL. Modulation transfer function (MTF), point spread function (PSF), and Strehl ratio were also calculated. All measures were taken for 3- and 5-mm pupils. RESULTS: The MTF, PSF, and Strehl ratio showed comparable values between IOLs (p > 0.05). There were no significant differences in DVA and CS between IOLs for all contrasts and pupils (p > 0.05). When spherically focused, mean DVA and NVA with the Crystalens HD IOL were ≥20/20 at 100 and 50% contrasts for both pupils. Monocular DVA, NVA, and CS were slightly better with 3- than 5-mm pupils, but without statistically significant differences. The Crystalens HD IOL showed about 0.75 and 0.50 D of depth of focus in its accommodative state and nonaccommodative state, respectively. CONCLUSIONS: The optical and visual quality with the nonaccommodatied Crystalens HD IOL was comparable to that of a monofocal IOL. If this lens can move 1.4 mm in the eye, it will provide high-quality optics for near vision as well.

Diurnal variations in visual performance for disposable contact lenses.

PURPOSE: The purpose of this study is to compare the visual performance provided by different daily disposable contact lenses and to analyze its variation over time. METHODS: Visual performance was evaluated in terms of visual acuity (VA) and contrast sensitivity (CS) in 15 myopic subjects (-0.50 to -4.00 diopters) who had been previously fitted with each one of the following seven types of soft contact lenses: DAILIES TOTAL1 (Alcon, Forth Worth, TX), DAILIES AquaComfort Plus (Alcon), 1-DAY ACUVUE TruEye (Johnson & Johnson Vision Care, Jacksonville, FL), 1-DAY ACUVUE MOIST (Johnson & Johnson Vision Care), SofLens daily disposable (Bausch & Lomb, Rochester, NY), Proclear 1 Day (CooperVision, Fairport, NY), and Clariti 1-Day (Sauflon, Twickenham, United Kingdom). We measured VA at three contrast levels (10%, 50%, and 100%) and CS for three spatial frequencies (10, 20, and 25 cycles/degree). These measurements were performed at 2-hr intervals during a 12-hr period of continuous wearing. Measurements were also performed with ophthalmic lenses before contact lens fitting. RESULTS: Two-way analysis of variance (ANOVA) results revealed significant differences across the lens types and over time for low-contrast VA only. For high- and medium-contrast VA, ophthalmic lens performed better than the contact lenses after 12 hr of use (without statistical differences among the contact lenses). Contrast sensitivity values also showed differences across lenses for the three spatial frequencies under analysis. For each particular lens type, no CS variations were observed with wearing time. Although some of the differences were not statistically significant, we found that, for many of the VA and CS measures, ophthalmic lens and DAILIES TOTAL1 yielded better values than the 1-DAY ACUVUE TruEye and Clariti 1-Day. CONCLUSIONS: Assessing VA at different contrasts and CS measurements allowed us to perform a visual function evaluation. Contact lens characteristics such as material and water content, among others, may be the cause of the differences in visual performance that emerged from this study. Our findings provide useful information for contact lens practitioners.

On-eye optical quality of daily disposable contact lenses for different wearing times.

PURPOSE: To quantify the optical quality of various daily disposable contact lenses in vivo and to ascertain its variation in terms of wearing time by means of objective non-invasive determination of wavefront patterns. METHODS: The crx1 adaptive-optics system was used to measure the wavefront aberrations in 15 myopic eyes before and at 2-h intervals after contact lens fitting, over a 12-h wearing period. Seven types of contact lenses having different material, water content and lens design were evaluated in this study: Dailies Total1, Dailies AquaComfort Plus, Proclear 1 Day, 1-Day Acuvue TruEye, 1-Day Acuvue moist, SofLens daily disposable and Clariti 1-Day. The aberration data were analysed by fitting Zernike polynomials up to the 5th-order for 3 and 5-mm pupils. The optical quality under each condition and at each point in time was described by means of the Root-Mean-Square (RMS) value of wavefront aberration, Modulation Transfer Function (MTF), Point Spread Function and cut-off spatial frequency. RESULTS: A RMS increase was observed after contact lens fitting as well as over time, both for a 3-mm and a 5-mm pupil. Each type of lens induced a different amount of wavefront aberrations, which vary over time also in a different manner. Dailies Total1 showed the lowest RMS values both at baseline and at the end of the day. In addition, Dailies Total1 provided the best MTF out of all the contact lenses that were assessed. These observations were reflected in higher cut-off spatial frequencies and visual resolution both at baseline and after 12 h of wearing time. CONCLUSIONS: Aberrometry makes it possible to analyse accurately and in vivo the optical quality of contact lenses and to assess how lenses having different characteristics - such as material or water content - behave for different wearing times. These variations across contact lenses may result in differences in visual performance.

Visual performance of two simultaneous vision multifocal contact lenses.

PURPOSE: To evaluate and compare the visual performance of two simultaneous vision multifocal contact lenses (CLs). METHODS: In this cross-over study design 20 presbyopic subjects were fitted with two different simultaneous vision multifocal CLs (the PureVision Multifocal Low Add and Acuvue Oasys for Presbyopia) in random order. After 1 month, binocular distance visual acuity (BDVA) under photopic (85 cd/m(2)) and mesopic (3 cd/m(2)) conditions, binocular near visual acuity (BNVA), binocular distance contrast sensitivity function (CSF) under photopic and mesopic conditions, binocular near CSF and defocus curve were measured. Subjects were then refitted with the alternative correction and the procedure was repeated. RESULTS: Mean BDVA under photopic conditions was similar for the Acuvue Oasys for Presbyopia and PureVision Multifocal Low Add: 0.01 ± 0.08 and 0.00 ± 0.08 logMAR, respectively (P = 0.45). Under mesopic conditions the values of BDVA were 0.20 ± 0.58 and 0.11 ± 0.09 logMAR, respectively (P = 0.005). Mean BNVA was 0.20 ± 0.05 and 0.15 ± 0.08 logMAR for the Acuvue Oasys and PureVision Low Add, respectively (P = 0.06). Binocular distance CSF testing revealed no statistically significant differences between lenses under photopic, mesopic or near conditions. Both lenses provided a comparable intermediate visual acuity. CONCLUSIONS: Both simultaneous vision multifocal CLs provided adequate distance visual quality under photopic and mesopic conditions, and better visual acuity was provided under mesopic conditions for the Purevision lens. Both lenses provided adequate visual performance at intermediate distance, but the near visual acuity appears to be insufficient for early presbyopes who require a moderately demanding near visual quality.

Myopic astigmatism correction: comparison of a Toric Implantable Collamer Lens and a bioptics technique by an adaptive optics visual simulator.

PURPOSE: To compare the optical and visual quality of a simulated Toric Implantable Collamer Lens (TICL) and a bioptics technique to treat high myopic astigmatism. METHODS: An adaptive optics visual simulator was used to simulate the vision after TICL implantation and a bioptics procedure from the wavefront aberration pattern for moderate and high-myopic astigmatism. Visual acuity (VA) at different contrasts and contrast sensitivity (CS) at 10, 20 and 25 cycles degree(-1) were measured for 3 and 5-mm pupils. Modulation Transfer Function (MTF) and Point Spread Function (PSF) were calculated for a 5-mm pupil. RESULTS: At a 3-mm pupil we only found statistically significant differences in VA between the two simulated surgeries at low-contrast for moderate- and high-myopic astigmatism (p < 0.05). Statistically significant differences were found in CS at 3-mm pupil between both procedures at the highest spatial frequency for moderate-myopic astigmatism and at all frequencies for high-myopic astigmatism (p < 0.05). At a 5-mm pupil we found statistically significant differences in VA and CS between both simulated surgeries at all contrasts and frequencies evaluated for both groups (p < 0.05). In all cases VA and CS were better with the TICL than with the bioptics technique. MTFs for the bioptics technique were worse than those computed for the TICL. The TICL showed less spread out of the PSF than the bioptics procedure. CONCLUSIONS: Simulated TICL and bioptics procedures provided good optical and visual quality, although TICL implantation provided slightly better outcomes than the bioptics procedure, especially when the pupil diameter was increased.

Foldable iris-fixated phakic intraocular lens vs femtosecond laser-assisted LASIK for myopia between -6.00 and -9.00 diopters.

PURPOSE: To compare visual, refractive, and clinical outcomes of foldable iris-fixated phakic intraocular lens (PIOL) implantation versus femtosecond laser-assisted LASIK for myopia between -6.00 and -9.00 diopters (D). METHODS: Forty-six myopic patients were randomized to undergo bilateral Artiflex (Ophtec BV) PIOL implantation or bilateral femtosecond laser-assisted conventional LASIK with the VISX S2 (Abbott Medical Optics). Refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuity, contrast sensitivity, corneal endothelial cell count, rate of retreatment, and complications were compared. RESULTS: Twelve months after surgery, no statistically significant differences were noted in spherical equivalent refraction (P=.19) or UDVA (P=.28), whereas CDVA was better in the PIOL group (P<.001). Spherical equivalent refraction was within ±0.50 D in 42 (91.3%) LASIK eyes and 41 (89.1%) PIOL eyes (P>.99). The percentage of eyes gaining lines of CDVA was significantly higher in the PIOL group (50.0% vs 8.7%; P<.001). Contrast sensitivity was better for PIOL eyes at 1.5 cycles per degree (cpd) (P=.03) and 6 cpd (P=.008). The LASIK eyes showed a mean endothelial cell count increase of 3.7%±2.8%, whereas PIOL eyes showed a mean decrease of 9.1%±2.0% (P<.001). The rate of retreatment was similar (P=.37), and no serious complications occurred in either group. CONCLUSIONS: The Artiflex PIOL provided better CDVA and contrast sensitivity at high spatial frequencies than femtosecond laser-assisted conventional LASIK, suggesting that PIOL implantation is a reasonable option for myopia between -6.00 and -9.00 D.

OCT for assessing artificial tears effectiveness in contact lens wearers.

PURPOSE: To apply a commercially available high-resolution spectral domain optical coherence tomographer (SOCT) to assess the change in tear volume after application of a new artificial tears formulation specifically developed for contact lens (CL) users. METHODS: Twenty OD from young healthy CL wearers (mean age, 24.7 ± 3.5 years) with refractive errors ranging from -0.75 to -2.50 D (mean, -1.56 ± 0.69 D) were examined. All subjects were fitted with Focus Dailies CL (Ciba Vision), and two drops of Blink Contacts (AMO), lubricating formulation specifically developed for CL wearers, were instilled after baseline measures. Tear meniscus volume (TMV) was measured immediately after and 1 min, 10, 30, and 60 min after instillation using the Copernicus HR SOCT (Optopol Tech., SA, Poland). TMV was calculated from the local area from tomograms assuming a regular distribution of the tear meniscus across the eyelid. Three scans were taken at each of the time points. RESULTS: Mean meniscus volume without CL was 1.35 ± 1.18 µL, volume with CL was higher, 1.71 ± 1.56 µL but not significantly different (mean difference, 0.36 ± 1.31 µL). After instillation of Blink Contacts eye drops, meniscus volume increased to an average of 4.10 ± 2.91 µL. Repeated measures analysis of variance showed that values after 10 min were significantly higher than before instillation of eye drops (p < 0.01; mean difference, 0.77 ± 0.65 µL). After 30 and 60 minutes, values of TMV decreased to almost baseline (average mean difference from baseline 0.19 ± 0.18 µL at t30, p < 0.001, and 0.06 ± 0.08 µL at t60, p = 0.004). CONCLUSIONS: High-resolution imaging of the lower tear film meniscus with SOCT systems provides useful measures of tear volume. An artificial tear formulation provides a change in tear volume that is maintained beyond 10 min, although further study, using control groups, would be desirable to determine the consistency of those higher-than-baseline values observed over time.