Three-Dimensional Digital Image Correlation Based on Speckle Pattern Projection for Non-Invasive Vibrational Analysis.

Non-contact vibration measurements are relevant for non-invasively characterizing the mechanical behavior of structures. This paper presents a novel methodology for full-field vibrational analysis at high frequencies using the three-dimensional digital image correlation technique combined with the projection of a speckle pattern. The method includes stereo calibration and image processing routines for accurate three-dimensional data acquisition. Quantitative analysis allows the extraction of several deformation parameters, such as the cross-correlation coefficients, shape and intensity, as well as the out-of-plane displacement fields and mode shapes. The potential of the methodology is demonstrated on an Unmanned Aerial Vehicle wing made of composite material, followed by experimental validation with reference accelerometers. The results obtained with the projected three-dimensional digital image correlation show a percentage of error below 5% compared with the measures of accelerometers, achieving, therefore, high sensitivity to detect the dynamic modes in structures made of composite material.

Crystalline lens gradient refractive index distribution in the guinea pig.

PURPOSE: The crystalline lens undergoes morphological and functional changes with age and may also play a role in eye emmetropisation. Both the geometry and the gradient index of refraction (GRIN) distribution contribute to the lens optical properties. We studied the lens GRIN in the guinea pig, a common animal model to study myopia. METHODS: Lenses were extracted from guinea pigs (Cavia porcellus) at 18 days of age (n = 4, three monolaterally treated with negative lenses and one untreated) and 39 days of age (n = 4, all untreated). Treated eyes were myopic (-2.07 D on average) and untreated eyes hyperopic (+3.3 D), as revealed using streak retinoscopy in the live and cyclopeged animals. A custom 3D spectral domain optical coherence tomography (OCT) system (λ = 840 nm, Δλ = 50 nm) was used to image the enucleated crystalline lens at two orientations. Custom algorithms were used to estimate the lens shape and GRIN was modelled with four variables that were reconstructed using the OCT data and a minimisation algorithm. Ray tracing was used to calculate the optical power and spherical aberration assuming a homogeneous refractive index or the estimated GRIN. RESULTS: Guinea pig lenses exhibited nearly parabolic GRIN profiles. When comparing the two age groups (18- and 39 day-old) there was a significant increase in the central thickness (from 3.61 to 3.74 mm), and in the refractive index of the surface (from 1.362 to 1.366) and the nucleus (from 1.443 to 1.454). The presence of GRIN shifted the spherical aberration (-4.1 µm on average) of the lens towards negative values. CONCLUSIONS: The guinea pig lens exhibits a GRIN profile with surface and nucleus refractive indices that increase slightly during the first days of life. GRIN plays a major role in the lens optical properties and should be incorporated into computational guinea pig eye models to study emmetropisation, myopia development and ageing.

Validation of an Affordable Handheld Wavefront Autorefractor.

SIGNIFICANCE: There is a critical need for tools that increase the accessibility of eye care to address the most common cause of vision impairment: uncorrected refractive errors. This work assesses the performance of an affordable autorefractor, which could help reduce the burden of this health care problem in low-resource communities. PURPOSE: The purpose of this study was to validate the commercial version of a portable wavefront autorefractor for measuring refractive errors. METHODS: Refraction was performed without cycloplegia using (1) a standard clinical procedure consisting of an objective measurement with a desktop autorefractor followed by subjective refraction (SR) and (2) with the handheld autorefractor. Agreement between both methods was evaluated using Bland-Altman analysis and by comparing the visual acuity (VA) with trial frames set to the resulting measurements. RESULTS: The study was conducted on 54 patients (33.9 ± 14.1 years of age) with a spherical equivalent (M) refraction determined by SR ranging from -7.25 to 4.25 D (mean ± SD, -0.93 ± 1.95 D). Mean differences between the portable autorefractor and SR were 0.09 ± 0.39, -0.06 ± 0.13, and 0.02 ± 0.12 D for M, J0, and J45, respectively. The device agreed within 0.5 D of SR in 87% of the eyes for spherical equivalent power. The average VAs achieved from trial lenses set to the wavefront autorefractor and SR results were 0.02 ± 0.015 and 0.015 ± 0.042 logMAR units, respectively. Visual acuity resulting from correction based on the device was the same as or better than that achieved by SR in 87% of the eyes. CONCLUSIONS: This study found excellent agreement between the measurements obtained with the portable autorefractor and the prescriptions based on SR and only small differences between the VA achieved by either method.

Three-dimensional evaluation of accommodating intraocular lens shift and alignment in vivo.

OBJECTIVE: To quantify 3-dimensionally the anterior segment geometry, biometry, and lens position and alignment in patients before and after implantation of the Crystalens-AO (Bausch & Lomb, Rochester, NY) accommodating intraocular lens (A-IOL). DESIGN: Prospective, observational study. PARTICIPANTS: Ten patients (20 eyes) with cataract before and after implantation of the Crystalens-AO A-IOL. METHODS: Custom full anterior segment 3-dimensional (3-D) spectral optical coherence tomography (OCT) provided with quantification tools was used to image the cornea, iris, and natural lens preoperatively and intraocular lens postoperatively. Measurements were obtained under phenylephrine preoperatively and under natural viewing conditions and phenylephrine (for accommodative efforts ranging from 0 to 2.5 diopters [D]) and pilocarpine postoperatively. MAIN OUTCOME MEASURES: Three-dimensional quantitative anterior segment images, corneal geometry and power, anterior chamber depth (ACD), lens thickness, pupil diameter, A-IOL shift with accommodative effort or drug-induced accommodation, and A-IOL alignment. RESULTS: Crystalline lens and IOLs were visualized and quantified 3-dimensionally. The average ACD were 2.64±0.24 and 3.65±0.35 mm preoperatively and postoperatively (relaxed state), respectively, and they were statistically significantly correlated (although their difference was not statistically correlated with lens thickness). The A-IOL did not shift systematically with accommodative effort, with 9 lenses moving forward and 11 lenses moving backward (under natural conditions). The average A-IOL shift under stimulated accommodation with pilocarpine was -0.02±0.20 mm. The greatest forward shift occurred bilaterally in 1 patient (-0.49 mm in the right eye and -0.52 mm in the left eye, under pilocarpine). The high right/left symmetry in the horizontal tilt of the crystalline lens is disrupted on IOL implantation. Accommodative IOLs tend to be slightly more vertically tilted than the crystalline lens, with increasing tendency with accommodative effort. Two subjects showed postoperative IOL tilts >9 degrees. Changes in pupillary diameter correlated with pilocarpine-induced A-IOL axial shift. Intermediate accommodative demands (1.25 D) elicited the greater shifts in axial A-IOL location and tilt and pupil diameter. CONCLUSIONS: Quantitative 3-D anterior segment OCT allows full evaluation of the geometry of eyes implanted with A-IOLs preoperatively and postoperatively. High-resolution OCT measurements of the Crystalens 3-D positioning revealed small (and in many patients backward) A-IOL axial shifts with both natural or drug-induced accommodation, as well as tilt changes with respect to natural lens and accommodative effort.

Ray tracing optimization: a new method for intraocular lens power calculation in regular and irregular corneas.

To develop a novel algorithm based on ray tracing, simulated visual performance and through-focus optimization for an accurate intraocular lens (IOL) power calculation. Custom-developed algorithms for ray tracing optimization (RTO) were used to combine the natural corneal higher-order aberrations (HOAs) with multiple sphero-cylindrical corrections in 210 higher order statistical eye models for developing keratoconus. The magnitude of defocus and astigmatism producing the maximum Visual Strehl was considered as the optimal sphero-cylindrical target for IOL power calculation. Corneal astigmatism and the RMS HOAs ranged from - 0.64 ± 0.35D and 0.10 ± 0.04 µm (0-months) to - 3.15 ± 1.38D and 0.82 ± 0.47 µm (120-months). Defocus and astigmatism target was close to neutral for eyes with low amount of HOAs (0 and 12-months), where 91.66% of eyes agreed within ± 0.50D in IOL power calculation (RTO vs. SRK/T). However, corneas with higher amounts of HOAs presented greater visual improvement with an optimized target. In these eyes (24- to 120-months), only 18.05% of eyes agreed within ± 0.50D (RTO vs. SRK/T). The power difference exceeded 3D in 42.2% while the cylinder required adjustments larger than 3D in 18.4% of the cases. Certain amounts of lower and HOAs may interact favourably to improve visual performance, shifting therefore the refractive target for IOL power calculation.

Scleral changes induced by atropine in chicks as an experimental model of myopia.

PURPOSE: To determine the effects of intravitreal atropine on scleral growth in the form-deprived chick as an experimental model of myopia. METHODS: Five groups of five chicks were studied from day 0-12 post-hatching. One group remained untreated (C), and four were form-deprived by monocular light diffusers to induce myopia. Two groups (RL and A) wore diffusers for 9 days, and the other two groups (D and D + A) wore diffusers throughout the study. Group D received no further treatment (myopia positive control). Groups A and D + A received intravitreal injections of atropine for days 9-12. Measurements of refractive error and axial length were performed on days 0, 9, and 12. Sclera changes were assessed in cartilaginous and fibrous layers by histological analysis. RESULTS: All form-deprived eyes had a myopic refractive error on day 9. All atropine-treated groups were hyperopic on day 12. The effect of atropine was most evident in Group D + A in which diffusers were maintained throughout treatment and changes in refractive error were statistically significant. The observed changes in axial length were in line with the changes in refractive error. The scleral fibrous layer thickness increased, and the sceral cartilaginous layer underwent a slight thinning compared to Group D, the myopia positive control. CONCLUSIONS: If the signals that induce growth remain during atropine treatment, morphological changes in sclera are produced: the scleral fibrous layer thickened, and the sceral cartilaginous layer thinned. These changes resulted in refractive error recovery, and the ocular growth was stopped. The data suggested the atropine was acting throughout the scleral fibrous layer.

Optical Evaluation of Intracorneal Ring Segment Surgery in Keratoconus.

Purpose: The purpose of this study was to assess the impact of different intracorneal ring segments (ICRS) combinations on corneal morphology and visual performance on patients with keratoconus. Methods: A total of 124 eyes from 96 patients who underwent ICRS surgery were analyzed and classified into 7 groups based on ICRS disposition and the diameter of the surgical zone (5- and 6-mm). Pre- and postoperative complete ophthalmological examinations were conducted. Corneal geometry, volume, and symmetry were studied. Zernike polynomials were used to build a virtual ray-tracing model to evaluate optical aberrations and the Visual Strehl (VS). Results: ICRS induced significant flattening across the cornea, being more pronounced on the anterior (+0.38 mm, P < 0.001) than on the posterior (+0.15 mm, P < 0.001) corneal radius. Asphericity experienced a larger change for a 6-mm surgical zone diameter (from -1.23 ± 1.1 to -1.86 ± 1.2, P < 0.001) than for a 5-mm zone (from -1.99 ± 1.1 to -2.10 ± 1.5, P = 0.536). Mean astigmatism was reduced by 2.05 D (P < 0.001). Combination four was the most effective in reducing astigmatism. Coma decreased by 30% on average and combination one produced an average reduction by 51% (P < 0.05). Patients experienced significant improvement in visual performance, best corrected visual acuity increased from 0.57 ± 0.21 to 0.69 ± 0.21 and VS changed from 0.049 ± 0.02 to 0.065 ± 0.041. Conclusions: ICRS combinations implanted within 5 mm diameter zone are more effective in flattening the cornea, whereas those implanted on 6 mm diameter are as effective in reducing astigmatism and are a good choice if the asymmetry and the intended flattening are smaller. Combinations with asymmetrical implants are the best option to regularize corneal surface. Translational Relevance: This study uses methods and metrics of optical research applied to daily clinical practice.

Correction: Assesment of the QuickSee wavefront autorefractor for characterizing refractive errors in school-age children.

[This corrects the article DOI: 10.1371/journal.pone.0240933.].

Effect of air-flow on the evaluation of refractive surgery ablation patterns.

An Allegretto Eye-Q laser platform (Wavelight GmbH, Erlangen, Germany) was used to study the effect of air-flow speed on the ablation of artificial polymer corneas used for testing refractive surgery patterns. Flat samples of two materials (PMMA and Filofocon A) were ablated at four different air flow conditions. The shape and profile of the ablated surfaces were measured with a precise non-contact optical surface profilometer. Significant asymmetries in the measured profiles were found when the ablation was performed with the clinical air aspiration system, and also without air flow. Increasing air-flow produced deeper ablations, improved symmetry, and increased the repeatability of the ablation pattern. Shielding of the laser pulse by the plume of smoke during the ablation of plastic samples reduced the central ablation depth by more than 40% with no-air flow, 30% with clinical air aspiration, and 5% with 1.15 m/s air flow. A simple model based on non-inertial dragging of the particles by air flow predicts no central shielding with 2.3 m/s air flow, and accurately predicts (within 2 µm) the decrease of central ablation depth by shielding. The shielding effects for PMMA and Filofocon A were similar despite the differences in the ablation properties of the materials and the different full-shielding transmission coefficient, which is related to the number of particles ejected and their associated optical behavior. Air flow is a key factor in the evaluation of ablation patterns in refractive surgery using plastic models, as significant shielding effects are found with typical air-flow levels used under clinical conditions. Shielding effects can be avoided by tuning the air flow to the laser repetition rate.

Corneal light transmission and roughness after refractive surgery.

PURPOSE: To determine the relation between the corneal light transmission measurements and the epithelial surface properties in hen corneas after different refractive surgery techniques photorefractive keratectomy, laser in situ keratomileusis, and laser-assisted subepithelial keratomileusis, and a group with only epithelial corneal removal (deepithelialization). METHODS: Five groups of hen corneas with different treatments and a control group were analyzed at 30 days. Direct transmittance and corneal light scattering were measured by a scatterometer developed by our group. Quantitative and systematic measurements of external and internal roughness and epithelium thickness were assessed using standard techniques developed for quantitative analysis of microphotographs of the corneal epithelium. RESULTS: Data analysis revealed that the roughness in the epithelial surface was associated with the corneal light transmission. The direct transmittance of light showed a significant correlation with the epithelial roughness in the control (r = -0.99, p < 0.05) and photorefractive keratectomy (r = -0.99, p < 0.05) groups. However, there was no relation between the epithelial thickness and the corneal light transmission measurements. CONCLUSIONS: The experimental results suggested that the roughness of the epithelial surfaces is related to the light transmission in the cornea.

Artificial iris performance for smart contact lens vision correction applications.

This paper presents the simulated performance assessment of an artificial iris embedded on a scleral contact lens using real data from an aniridia patient. The artificial iris is based on guest-host liquid crystal cells (GH-LCD) in order to actively modify the transmittance of the lens and effective pupil size. Experimental validation of the GH-LCD spectrum and iris contrast (determined to be 1:2.1) enabled the development of optical models that include the effect of a small pupil on image quality and visual quality on an optical system with aniridia characteristics. Visual simulations at different light conditions (high/low photopic and mesopic) demonstrated the theoretical capacity of the customized artificial iris smart contact lens to expand the depth-of-focus and decrease the optical aberrations (in particular, the spherical aberration). The visual modelling suggests a maximum depth-of-focus value for a 2-mm pupil diameter for both eyes as follows: 3D (1,000 cd/m2), 2D (10 cd/m2) and 0.75D (1 cd/m2). This work demonstrates the beneficial optical effects of an active artificial iris, based on visual simulations in response to different light levels, and enables further experimental investigation on patients to validate the dynamic light attenuation and visual performance of smart contact lenses with GH-LCD.

Bifocal and Multifocal Contact Lenses for Presbyopia and Myopia Control.

Bifocal and multifocal optical devices are intended to get images into focus from objects placed at different distances from the observer. Spectacles, contact lenses, and intraocular lenses can meet the requirements to provide such a solution. Contact lenses provide unique characteristics as a platform for implementing bifocality and multifocality. Compared to spectacles, they are closer to the eye, providing a wider field of view, less distortion, and their use is more consistent as they are not so easily removed along the day. In addition, contact lenses are also minimally invasive, can be easily exchangeable, and, therefore, suitable for conditions in which surgical procedures are not indicated. Contact lenses can remain centered with the eye despite eye movements, providing the possibility for simultaneous imaging from different object distances. The main current indications for bifocal and multifocal contact lenses include presbyopia correction in adult population and myopia control in children. Considering the large numbers of potential candidates for optical correction of presbyopia and the demographic trends in myopia, the potential impact of contact lenses for presbyopia and myopia applications is undoubtedly tremendous. However, the ocular characteristics and expectations vary significantly between young and older candidates and impose different challenges in fitting bifocal and multifocal contact lenses for the correction of presbyopia and myopia control. This review presents the recent developments in material platforms, optical designs, simulated visual performance, and the clinical performance assessment of bifocal and multifocal contact lenses for presbyopia correction and/or myopia progression control.

Assesment of the QuickSee wavefront autorefractor for characterizing refractive errors in school-age children.

PURPOSE: To assess the performance of an open-view binocular handheld aberrometer (QuickSee) for diagnosing refractive errors in children. METHODS: 123 school-age children (9.9 ± 3.3 years) with moderate refractive error underwent autorefraction (AR) with a standard desktop device and subjective refraction (SR), with or without cycloplegia to determine their eyeglass prescription. Measurements with QuickSee (QS) were taken in 62 of these patients without cycloplegia (NC), and in 61 under cycloplegia (C). Differences in refraction values (AR vs SR vs QS) as well as the visual acuity (VA) achieved by the patients with each method (QS vs SR) were used to evaluate the performance of the device in measuring refractive error. RESULTS: The spherical equivalent refraction obtained by QS agreed within 0.5 D of the SR in 71% (NC) and 70% (C) of the cases. Agreement between the desktop autorefractor and SR for the same threshold was of 61% (NC) and 77% (C). VA resulting from QS refractions was equal to or better than that achieved by SR procedure in 77% (NC) and 74% (C) of the patients. Average improvement in VA with the QS refractions was of 8.6 and 13.4 optotypes for the NC and C groups respectively, while the SR procedure provided average improvements of 8.9 (NC) and 14.8 (C) optotypes. CONCLUSIONS: The high level of agreement between QuickSee and subjective refraction together with the VA improvement achieved in both study groups using QuickSee refractions suggest that the device is a useful autorefraction tool for school-age children.

Morphological changes of human crystalline lens in myopia.

Ocular biometric parameters, including full shape crystalline lens, were assessed in myopes and emmetropes using 3-D optical coherence tomography. The anterior chamber depth, the radius of the curvature of the anterior cornea, anterior lens, and posterior lens, lens thickness, lens equatorial diameter, surface area, equatorial position, volume, and power, were evaluated as functions of refractive errors and axial lengths while controlling for age effects. The crystalline lens appears to change with myopia consistent with lens thinning, equatorial, and capsular stretching while keeping constant volume. Axial elongation appears counteracted by a crystalline lens power reduction, while corneal power remains unaffected.

Effect of intraocular lens decentration on image quality tested in a custom model eye.

PURPOSE: To evaluate the effect of intraocular lens (IOL) decentration on optical aberrations with different IOL designs. SETTING: Visual Optics and Biophotonics Laboratory, Instituto de Óptica, Consejo Superior de Investigaciones Científicas, Madrid, Spain. DESIGN: Experimental study. METHODS: The following 18 aspheric IOLs immersed in a physical model eye were measured using a laser ray-tracing aberrometer: 10 Vivinex XY1 with spherical aberration correction of -0.18 µm (V-0.18), 4 Tecnis 1P ZCB00V with spherical aberration correction of -0.27 µm (T-0.27), and 4 Acrysof 1P SN60WF with spherical aberration correction of -0.17 µm (A-0.17). The optical aberrations were evaluated with the IOL on axis and 0.4 mm and 0.7 mm laterally decentered. The laser ray tracing-measured aberrations were compared with aberrations estimated using virtual ray tracing. Retinal image quality was evaluated from the modulation transfer function (MTF) and visual Strehl ratio. RESULTS: Wave aberration measurements of the same IOL were highly repetitive (deviation <0.02 µm). Astigmatism and coma increased with decentration at a rate of 0.18 µm/mm and 0.19 µm/mm for the V-0.18, 0.20 µm/mm and 0.32 µm/mm for the T-0.27, and 0.26 µm/mm and 0.39 µm/mm for the A-0.17, respectively. The 0.7 mm lateral decentration decreased the visual Strehl ratio by 2.23 times for the V-0.18, by 2.8 times for the T-0.27, and by 3.2 times for the A-0.17. The V-0.18 showed the highest MTF and visual Strehl values for all centration values. CONCLUSIONS: Lateral decentration resulted in decreased retinal image quality. The V-0.18 was the most immune design to optical degradation caused by decentration.

Estimation of intraocular lens position from full crystalline lens geometry: towards a new generation of intraocular lens power calculation formulas.

In a cataract surgery, the opacified crystalline lens is replaced by an artificial intraocular lens (IOL). To optimize the visual quality after surgery, the intraocular lens to be implanted must be selected preoperatively for every individual patient. Different generations of formulas have been proposed for selecting the intraocular lens dioptric power as a function of its estimated postoperative position. However, very few formulas include crystalline lens information, in most cases only one-dimensional. The present study proposes a new formula to preoperatively estimate the postoperative IOL position (ELP) based on information of the 3-dimensional full shape of the crystalline lens, obtained from quantitative eye anterior segment optical coherence tomography imaging. Real patients were measured before and after cataract surgery (IOL implantation). The IOL position and the postoperative refraction estimation errors were calculated by subtracting the preoperative estimations from the actual values measured after surgery. The proposed ELP formula produced lower estimation errors for both parameters -ELP and refraction- than the predictions obtained with standard state-of-the-art methods, and opens new avenues to the development of new generation IOL power calculation formulas that improve refractive and visual outcomes.

Rose Bengal and Green Light Versus Riboflavin-UVA Cross-Linking: Corneal Wound Repair Response.

Purpose: To study corneal wound healing after two cross-linking techniques using either rose bengal and green light (RGX) or the conventional treatment using riboflavin and UVA radiation (UVX). Methods: Corneas of New Zealand rabbits were monolaterally treated with UVX (21 eyes) or RGX (25 eyes). Treatments involved corneal de-epithelialization (8-mm diameter), soaking with photosensitizer (0.1% riboflavin in 20% dextran for 30 minutes for UVX; 0.1% rose bengal for 2 minutes for RGX), and light irradiation (370 nm, 3 mW/cm2, 30 minutes for UVX; 532 nm, 0.25 W/cm2, 7 minutes for RGX). Contralateral eyes were used as controls. Clinical follow-up included fluorescein staining, haze measurement, and pachymetry. Healing events analyzed after euthanasia at 2, 30, and 60 days included cell death (TUNEL assay), cell proliferation (BrdU [bromodeoxyuridine] immunofluorescence), and differentiation to myofibroblasts (α-SMA [alpha smooth muscle actin] immunohistochemistry). Results: Re-epithelialization and pachymetries were similar after RGX and UVX. The haze from day 1 to 15 was greater after UVX. Cell death was deeper after UVX, being localized in the anterior and middle stroma, and was superficial (anterior third) after RGX. Cell proliferation appeared after 2 days and was localized in the middle and posterior stroma in the UVX group but was superficial in the RGX group. After 60 days the number of stromal cells had not returned to the control number in either group. Conclusions: The deeper and longer-lasting cell damage caused by UVX compared to RGX may underlie the slower cell repopulation after UVX and other differences in healing. Shallower damage and a shorter treatment time suggest that RGX may be appropriate for stiffening thin corneas.

OCT-based full crystalline lens shape change during accommodation in vivo.

The full shape of the accommodating crystalline lens was estimated using custom three-dimensional (3-D) spectral OCT and image processing algorithms. Automatic segmentation and distortion correction were used to construct 3-D models of the lens region visible through the pupil. The lens peripheral region was estimated with a trained and validated parametric model. Nineteen young eyes were measured at 0-6 D accommodative demands in 1.5 D steps. Lens volume, surface area, diameter, and equatorial plane position were automatically quantified. Lens diameter & surface area correlated negatively and equatorial plane position positively with accommodation response. Lens volume remained constant and surface area decreased with accommodation, indicating that the lens material is incompressible and the capsular bag elastic.

Three-dimensional OCT based guinea pig eye model: relating morphology and optics.

Custom Spectral Optical Coherence Tomography (SOCT) provided with automatic quantification and distortion correction algorithms was used to measure the 3-D morphology in guinea pig eyes (n = 8, 30 days; n = 5, 40 days). Animals were measured awake in vivo under cyclopegia. Measurements showed low intraocular variability (<4% in corneal and anterior lens radii and <8% in the posterior lens radii, <1% interocular distances). The repeatability of the surface elevation was less than 2 µm. Surface astigmatism was the individual dominant term in all surfaces. Higher-order RMS surface elevation was largest in the posterior lens. Individual surface elevation Zernike terms correlated significantly across corneal and anterior lens surfaces. Higher-order-aberrations (except spherical aberration) were comparable with those predicted by OCT-based eye models.

Evaluation of the True Wavefront Aberrations in Eyes Implanted With a Rotationally Asymmetric Multifocal Intraocular Lens.

PURPOSE: Standard evaluation of aberrations from wavefront slope measurements in patients implanted with a rotationally asymmetric multifocal intraocular lens (IOL), the Lentis Mplus (Oculentis GmbH, Berlin, Germany), results in large magnitude primary vertical coma, which is attributed to the intrinsic IOL design. The new proposed method analyzes aberrometry data, allowing disentangling the IOL power pupillary distribution from the true higher order aberrations of the eye. METHODS: The new method of wavefront reconstruction uses retinal spots obtained at both the near and far foci. The method was tested using ray tracing optical simulations in a computer eye model virtually implanted with the Lentis Mplus IOL, with a generic cornea or with anterior segment geometry obtained from custom quantitative spectral-domain optical coherence tomography in a real patient. The method was applied to laser ray tracing aberrometry data at near and far fixation obtained in a patient implanted with the Lentis Mplus IOL. RESULTS: Higher order aberrations evaluated from simulated and real retinal spot diagrams following the new reconstruction approach matched the nominal aberrations (approximately 98%). Previously reported primary vertical coma in patients implanted with this IOL lost significance with the application of the proposed reconstruction. CONCLUSIONS: Custom analysis of ray tracing-based retinal spot diagrams allowed decoupling of the true higher order aberrations of the patient's eye from the power pupillary distribution of a rotationally asymmetric multifocal IOL, therefore providing the appropriate phase map to accurately evaluate through-focus optical quality. [J Refract Surg. 2017;33(4):257-265.].