Secondary Spherical Aberration Research Articles

Higher order aberrations and retinal image quality during short-term accommodation in myopic and non-myopic children.

Despite the known associations between near work and myopia, and retinal image quality and eye growth, accommodation-induced changes in higher order aberrations (HOA's) and retinal image quality in children with different refractive errors are poorly understood. Ocular HOA's were measured using a Hartmann-Shack wavefront sensor (COAS-HD, Wavefront Sciences) in 18 myopic and 18 age- and sex-matched non-myopic children during short-term accommodation tasks (four demands of 0, 3, 6 and 9 D) presented using a Badal optometer. Eighth order Zernike polynomials were fitted across a 2.3 mm pupil diameter to determine refractive power vectors (M, J180 and J45 ) and the accommodation error, and a 4 mm pupil was used for HOA analyses. Retinal image quality was examined using the visual Strehl ratio based on the optical transfer function (VSOTF) for third to eighth radial orders only. Most refractive error group differences were observed for the 6 and 9 D demands. Myopic children underwent greater changes in with-the-rule astigmatism (J180 ), higher order and third order RMS values, primary vertical ( ) and horizontal coma ( ), and several other individual Zernike coefficients compared with non-myopic children (all refractive error group by demand interaction p-values of ≤0.02). Non-myopic children exhibited a greater negative shift in primary ( ) and positive shift in secondary spherical aberration ( ) (both refractive error group by demand interaction p-values of ≤0.002). The VSOTF degraded for the 6 and 9 D demands in both groups, but the myopic children underwent a greater mean (SE) reduction from 0 D of -0.274 (0.048) for the 9 D demand, compared with -0.131 (0.052) for the non-myopic children (p = 0.001). These results may have implications for the association between near work, accommodation and myopia development, particularly related to the use of short working distances during near tasks.

Spherical Aberration and Accommodative Insufficiency: Is There a Link?

Given the relationship between spherical aberrations and accommodation, the study of these aberrations can be helpful to understand accommodative response in subjects with accommodative dysfunctions. The purpose of this study was to evaluate on-axis and off-axis changes of primary and secondary spherical aberrations, Z(4,0) and Z(6,0), with accommodation in subjects with accommodative insufficiency (AI). Ten subjects with AI and eleven without any accommodative dysfunction (control) participated in this study. On-axis defocus Z(2,0), Z(4,0), and Z(6,0) were obtained in both groups with a Hartmann–Shack aberrometer for the unaccommodated state and with 1.00 D, 2.44 D, 3.83 D, and 4.73 D of accommodative stimuli. Z(4,0) and Z(6,0) were also measured on 11.5° and 23° temporal, nasal, superior, and inferior retinal areas for unaccommodated state and for 2.44 D of accommodative stimulus. In the control group, Z(4,0) became more negative with accommodation and Z(6,0) became more positive, as was expected according to previous studies. This tendency was not observed in the group of subjects with AI group for Z(4,0) or for Z(6,0). No differences on off-axis Z(4,0) and Z(6,0) were observed between the groups. The changes of spherical aberrations with accommodation seem different in subjects with AI compared to those without any accommodative dysfunction. Those with AI do not present a decrease in Z(4,0) and an increase in Z(6,0) with accommodation as occurs in eyes without this type of dysfunction. Understanding how the optics of the eye changes with accommodation can be helpful to understand the origin of accommodative dysfunctions.

Assessment of central and peripheral accommodative lag by aberrometry

Accommodation lag is important factor for normal vision. Higher lag of accommodation may cause various ocular symptoms particularly during near tasks. In this study, the lag of accommodation was assessed in the peripheral retina and it was compared with the central accommodative lag with aberrometer. In this cross-sectional study, fifty-three young subjects with normal visual acuity and without any active ocular disease or past ocular surgery were included. Aberrations in the central and peripheral field of view up to 30° off axis from the centre in horizontal and vertical meridian in 10° steps were measured with Hartmann-Shack aberrometer with stimulation of accommodation by -2.50D lens. Accommodative stimulus and accommodative response were calculated with defocus and hence accommodative lag was obtained. Accommodative lag in the centre and periphery was compared. Repeated measure of ANOVA showed that there were significant differences in lag of accommodation in various eccentricities (F(8.912, 454.514) = 2.372, p = 0.013). Pairwise test showed that lag in the centre was similar with lag on other peripheral field of view (p > 0.05). However, accommodative lag at 10° nasal field was significantly lower than the lag at 20° temporal, 20° nasal, 30° temporaland 30° nasal (p < 0.05). Similarly, lag at 10° superior fixation was lower than lag at 20° temporal, 20° nasal, 30° temporal and 30° nasal fixations (p < 0.05). We found higher lag of accommodation in horizontal off-axis fixations in comparison to that of vertical off-axis fixations (p < 0.05). Lag of accommodation was positive correlated with vertical coma and primary spherical aberrations but negative correlated with secondary spherical aberrations (p < 0.05). Thus, Hartmann-Shack aberrometer was successfully used to assess accommodative lag in the peripheral field of view up to 60° visual field. Peripheral lag of accommodation depends up on eccentricity. Lag was found higher in horizontal off-axis fixation than at vertical fixations. Coma and spherical aberration had association with lag.

Analysis of a novel hydrophobic acrylic enhanced monofocal intraocular lens compared to its standard monofocal type on the optical bench

IntroductionThe aim of this laboratory study is to objectively analyze the new hydrophobic, acrylic, enhanced monofocal intraocular lens Acunex Quantum (AN6Q) and compare it with the monofocal platform Acunex AN6. MethodsTwo IOL models were analyzed (Acunex Quantum AN6Q and Acunex AN6, Teleon Surgical, Spankeren, Netherlands), each having the same refractive power of + 22.0 D, on the optical bench with the OptiSpheric IOL PRO 2. The measurements followed the guidelines of the International Standard Organization with following parameters: ISO 2 cornea (+ 0,28 µ), ISO 11979/2, lens placement in situ in NaCl with 35° temperature, 546 nm and selection of different aperture sizes (3.0 mm vs 4.5 mm). The aberrations of each IOL were evaluated by the WaveMaster IOL 2, a high-resolution Shack-Hartmann sensor in reverse projection setup. An in-situ model eye was used according to ISO 11979 in NaCl (n = 1.337) with 546 nm, mask width 4.51. Zernike polynomials up to 10th order were determined by means of the measured wavefront that describe the optical properties of the IOL.ResultsThrough frequency modulation transfer function (mean) at 50 lp/mm (AN6Q/AN6 centered) was 0.687/0.731 (3.0 mm aperture) and 0.400/0.509 (4.5 mm aperture). The SR (mean) was 0.592/0.809 (3.0 mm) and 0.332/0.372 (4.5 mm). The MTF (mean) at 50 lp/mm (AN6Q/AN6 decentered by 1 mm) was 0.413/0.478 (3.0 mm) and 0.257/0.229 (4.5 mm). The SR (mean) was 0.393/0.404 (3.0 mm) and 0.183/0.212 (4.5 mm). The MTF (mean) at 50 lp/mm (AN6Q/AN6 tilted by 5°) was 0.508/0.710 (3.0 mm) and 0.337/0.513 (4.5 mm). The SR (mean) was 0.508/0.760 (3.0 mm) and 0.235/0.2372 (4.5 mm). AN6Q showed MTF peak of 0.55 with an enlarged depth of power of about 2.5 D and two cusps in the MTF curve. The spherical aberration Z 4–0 was about -0.21 µm and the secondary spherical aberration Z 6–0 was about 0.16 µm. No other relevant aberration showed up.ConclusionThe new, enhanced monofocal AN6Q provides an extended range of focus with only slight decrease in contrast quality. Both types of the hydrophobic, acrylic Acunex IOL platform have its particular advantages in clinical settings and therefore its importance, respectively.

Anterior and posterior corneal higher-order aberrations in early diagnosis and grading of keratoconus

ABSTRACTClinical relevanceEvaluation of corneal higher-order aberrations can be used clinically to diagnose early cases of keratoconus as well as to classify the severity of keratoconus.BackgroundTo investigate the anterior and posterior corneal higher-order aberrations (HOAs) up to the sixth order and their ability to identify early keratoconus (KCN) as well as differentiate different severities of KCN using cross-validation analysis.MethodsThis prospective cross-sectional comparative study was performed at a tertiary eye hospital in Tehran, Iran, in 2019. The study sample consisted of 95 eyes of 95 patients with KCN and 53 eyes of 53 normal individuals. The eyes with KCN were classified into three groups based on the Amsler–Krumeich classification system: group 1 (mild KCN), group 2 (moderate KCN), and group 3 (severe KCN). Corneal wavefront analysis was performed using Pentacam HR.ResultsBased on the magnitude of AUC, posterior vertical secondary coma (Z5−1) had an excellent discriminant ability (AUC: 0.91) and anterior vertical coma (Z3−1) and anterior vertical secondary coma (Z5−1) had a good discriminant ability (0.8 < AUC < 0.89) for differentiating eyes with mild KCN from normal eyes. The anterior and posterior primary spherical aberrations (Z4°) had an excellent ability (AUC > 0.9), and anterior secondary spherical aberration (Z6°) had a good ability (AUC: 0.83) for differentiating moderate from mild KCN. In the differentiation of severe from moderate KCN, anterior and posterior primary aspherical aberrations (Z4°) had a good AUC value (AUC > 0.8).ConclusionComa-like aberrations had a good discriminant ability between normal eyes and eyes with mild KCN. Spherical aberrations showed a good ability for differentiating between different stages of KCN. The cut-off values reported in this study can be used for early detection of KCN as well as classification of KCN severity.

Higher order aberrations and retinal image quality during short-term accommodation in children

Changes in higher order aberrations (HOA’s) and retinal image quality during accommodation have not previously been examined in children. This study measured ocular HOA’s in ninety non-myopic, school-aged children during short-term accommodation tasks at 0, 3, 6, and 9 D demands presented via a Badal optometer mounted to a Hartmann-Shack wavefront aberrometer (COAS-HD, Wavefront Sciences). Eighty-four participants who exhibited active accommodation were included in the analyses. An eighth order Zernike polynomial was fit across a 2.3 mm, 4 mm, and natural pupil diameter to evaluate changes in refractive power vectors (M, J180, and J45), accommodation errors (lags and leads), HOA root mean square (RMS) variables, individual Zernike coefficients, and the visual Strehl ratio based on the optical transfer function (VSOTF). All HOA RMS variables changed significantly with accommodation, with the greatest change observed for the 9 D demand. Of the individual Zernike coefficients, primary (C40) and secondary spherical aberration (C60) exhibited the greatest magnitude of change, becoming negative and positive with increasing accommodation, respectively. The VSOTF changed significantly with greater accommodation for both the 4 mm and natural pupil size, becoming significantly worse for the 9 D demand. HOA’s increase and retinal image quality decreases significantly during higher levels of accommodation in children, similar to adults. These findings provide a greater understanding of the optical properties of children’s eyes and insights into possible mechanisms for the association between accommodation, near work, and refractive error development.

MEMS-in-the-lens 3D beam scanner for in vivo microscopy.

The "MEMS-in-the-lens" active lens for a laser scanning microscope comprises a high numerical aperture front element, a 3D+ MOEMS beam scanner and a collimating back lens. The scanner utilizes a silicon gimbal with SU-8 polymer flexures and deformable membrane mirror. The mirror aperture is 4 mm in diameter, and is capable of 9 μm deflection for focus control, with four annular electrodes to allow tuning of primary and secondary spherical aberration. The gimbal supports tip/tilt actuation up to ±3° for lateral beam scanning. We show confocal imaging using a benchtop mockup of the active lens, illustrating the potential for this approach to support 3D microscopy for optical biopsy applications.

Simulation of commercial vs theoretically optimised contact lenses for presbyopia.

To compare theoretically optimised bifocal contact lens optical designs to commercially available optical designs for presbyopia. Retinal images were simulated, using a numerical eye model, from -6 (i.e., near vision) to +2D for each 0.25D. Ten optical profiles were simulated. Four of them corresponded to commercial contact lenses (i.e., Acuvue Oasys for Presbyopia®, Air Optix Aqua Multifocal®, Purevision Multifocal® and Distance Biofinity Multifocal®). We also included six optimised profiles: (1) a combination of primary and secondary spherical aberration, (2) bifocal profiles with 2, 5 and 8 concentric zones, and (3) a combination of spherical aberrations with the 5 and 8 zones profiles. Twenty subjects scored the quality of vision of calculated images (i.e., three high-contrast 0.40 logMAR letters) for each design and vergence with a five-item continuous grading scale. They viewed these images through their best sphero-cylindrical correction and a 3-mm pupil to limit the impact of their aberrations. To quantify the ability of a bifocal optic to maintain a certain level of quality of vision, we calculated two criteria: (1) the area under the through-focus quality of vision curve higher than 2 (i.e., limit between poor and fair quality of vision) normalised by the same area calculated on the naked eye's curve, and (2) the width of the curve at a level of 2 (i.e., depth-of-focus). Commercial contact lens profiles did not give an image quality and depth-of-focus as good as the theoretically optimised optical profiles. Based on these two criteria, the best bifocal profiles were those with 5 and 8 concentric zones. Important inter-individual variations were observed for all profiles. We also observed that some subjects did not obtain any benefit with all the designs whereas others seemed to be satisfied whatever the optical profiles. Our previously optimised designs with 5 and 8 zones gave the best benefit and depth-of-focus. As their image quality is better than commercially available designs, it would be interesting to prototype these designs and to test them in a clinical setting.

Impact of Spherical Aberration Terms on Multifocal Contact Lens Performance.

To investigate the impact of the primary (PSA) and secondary (SSA) spherical aberration terms on visual performance (VP) in presbyopes, as measured using multifocal (MFCL) soft contact lenses on eye. Seventeen presbyopes (age: 55.1 ± 6.9 years) wore seven commercial lenses (four center-near (MFCL N), one center-distance (MFCL D), one bifocal, and one single vision control). Unaided and with each lens on eye, the PSA and SSA terms were obtained with an aberrometer, the BHVI-EyeMapper (low illumination, natural and 4 mm pupil diameter). High- and low-contrast distance visual acuity, contrast sensitivity, high-contrast visual acuities at near, and range of clear vision were measured. In addition, subjective VP variables included clarity of vision at distance and near, ghosting, and overall vision satisfaction. Pearson's correlation was used to determine the association between the PSA and SSA terms and the VP variables. PSA (natural pupil) was more negative (P < .05) with the MFCL N (mean PSA = -0.053 ± 0.080 μm) and bifocal (PSA = +0.005 ± 0.067 μm) lenses and more positive with the MFCL D lens (PSA = +0.208 ± 0.160 μm) than the control (+0.067 ± 0.072 μm). SSA (natural pupil) was significantly more positive for the MFCL N lenses (mean SSA = +0.025 ± 0.029 μm) compared to the control (SSA = -0.001 ± 0.017 μm). PSA and SSA terms were significantly (P < .05) correlated with 78% and 56% of VP variables, respectively, but the correlation coefficients were weak, ranging between |0.210| and |0.334|. Although distance variables showed improved VP with more positive PSA or negative SSA, most near variables showed improved VP with more negative PSA. Range of clear focus was greater for more negative PSA terms. The amount and direction of PSA and SSA terms, as measured with different MFCLs on eye, can affect VP at different distances. Results of this study may provide useful information when designing new or optimize existing MFCLs for improved VP at specific distances.

In Vitro Aberrometric Assessment of a Multifocal Intraocular Lens and Two Extended Depth of Focus IOLs.

Purpose To analyze the “in vitro” aberrometric pattern of a refractive IOL and two extended depth of focus IOLs. Methods A special optical bench with a Shack-Hartmann wavefront sensor (SH) was designed for the measurement. Three presbyopia correction IOLs were analyzed: Mini WELL (MW), TECNIS Symfony ZXR00 (SYM), and Lentis Mplus X LS-313 MF30 (MP). Three different pupil sizes were used for the comparison: 3, 4, and 4.7 mm. Results MW generated negative primary and positive secondary spherical aberrations (SA) for the apertures of 3 mm (−0.13 and +0.12 μm), 4 mm (−0.12 and +0.08 μm), and 4.7 mm (−0.11 and +0.08 μm), while the SYM only generated negative primary SA for 4 and 4.7 mm apertures (−0.12 μm and −0.20 μm, resp.). The MP induced coma and trefoil for all pupils and showed significant HOAs for apertures of 4 and 4.7 mm. Conclusions In an optical bench, the MW induces negative primary and positive secondary SA for all pupils. The SYM aberrations seem to be pupil dependent; it does not produce negative primary SA for 3 mm but increases for higher pupils. Meanwhile, the HOAs for the MW and SYM were not significant. The MP showed in all cases the highest HOAs.

Distribution and compensation mechanism of aberrations between anterior and posterior surface of the cornea in myopia and myopic astigmatism eyes

Objective: To study the compensation mechanism of aberrations between anterior and posterior corneal surface, and to investigate the correlations between corneal aberrations and K values, intraocular pressure and central corneal thickness. Methods: One hundred and sixty-one subjects (300 eyes) with myopia and myopic astigmatism were recruited randomly. Corneal aberrations (anterior, posterior and total) in three different optical zones (2 mm, 4 mm, and 6 mm) centered on the corneal vertex were assessed with a corneal topographer (Sirius). We also calculated compensation factors (CFs) as a measure of the relative efficiency of the aberration compensation mechanism. Astigmatism was divided into corneal astigmatism and non-corneal astigmatism. Mann-Whitney U test was utilized for the comparison of different aberrations and CFs between the two astigmatism groups. Spearman correlation was applied to analyze the correlations between corneal aberrations and K values, intraocular pressure and central corneal thickness. Results: As the order of the aberrations elevated from the second to the seventh, the RMS values decreased significantly. The larger the optical zone, the greater the values of aberrations and the lower the percentage of the compensation mechanism among all the Zernike terms. At the same time, as the order of the aberrations increased, the predominance of the compensation mechanism was increasingly obvious. Slight compensation of spherical aberration (Z40) was observed in the peripheral. In the center of the analyzing zones (2 mm), compensation mechanism represented in coma (Z3±1), and it disappeared in the peripheral. We detected slight compensation of the corneal astigmatism (Z2±2) in the surrounding zone, although the compensation factors were closed to zero in diverse optical zones. Superposition was found in trefoil (Z3±3) straightly. Nevertheless, a tendency towards compensation was discovered with the enlargement of the optical zones. And the secondary spherical aberration (Z60) behaved compensation continuously. However, similar compensation was discovered between the right eye and left eye in different analyzing optical zones. There were significant correlations between the flattest K values and Z2±2, Z3±3and Z40 in the anterior, posterior and total cornea. It was similar with the steepest K values. When the optical zone expanded to 6 mm, Z3±1 and Z40 significantly decreased with intraocular pressure (rcoma=-0.188, P<0.05. rspherical=-0.147, P<0.05). No correlation was found between various aberrations and central corneal thickness (P>0.05). Conclusions: Compensation dominated in the corneal center, while the percentage decreased gradually as the optical zone extended. Slight compensation in astigmatism and spherical aberration between the anterior and posterior cornea may be benificial to the scotopic visual quality. Corneal aberrations were significantly related to K values and intraocular pressure. (Chin J Ophthalmol, 2016, 52: 840-849).

Morphology, topography, and optics of the orthokeratology cornea.

The goal of this work was to objectively characterize the external morphology, topography, and optics of the cornea after orthokeratology (ortho-k). A number of 24 patients between the ages of 17 and 30 years (median=24 years) were fitted with Corneal Refractive Therapy® contact lenses to correct myopia between −2.00 and −5.00 diopters (D) (median=−3.41 D). A classification algorithm was applied to conduct an automatic segmentation based on the mean local curvature. As a result, three zones (optical zone, transition zone, and peripheral zone) were delimited. Topographical analysis was provided through global and zonal fit to a general ellipsoid. Ray trace on partially customized eye models provided wave aberrations and retinal image quality. Monozone topographic description of the ortho-k cornea loses accuracy when compared with zonal description. Primary (C40) and secondary (C60) spherical aberration (SA) coefficients for a 5-mm pupil increased 3.68 and 19 times, respectively, after the treatments. The OZ area showed a strong correlation with C40 (r=−0.49, p<0.05) and a very strong correlation with C60 (r=0.78, p<0.01). The OZ, as well as the TZ, areas did not correlate with baseline refraction. The increase in the eye’s positive SA after ortho-k is the major factor responsible for the decreased retinal optical quality of the unaccommodated eye.

Simulated effect of aspheric transition zone ablation profiles on optical aberrations after customized myopia ablation

PurposeTo understand and study the effect of transition zone on wavefront aberrations after laser refractive surgery is important for improving visual correction outcomes. MethodsBased on the ablation profiles of optical zone and aspheric transition zone for wavefront-guided refractive surgery, the influence of aspheric transition zone on the induced wavefront aberrations was studied. ResultsThe types of ablation profile of aspheric transition zone had a significant influence on the induced higher-order wavefront aberrations. The induced aberrations were mainly spherical aberration and coma. In addition, the profile #9 showed that the induced spherical aberration had a lower RMS value than that in other profiles and yet the induced secondary astigmatism was relatively larger. Furthermore, secondary spherical aberration in the profile #9 was slightly lower than that in other profiles. ConclusionThe residual higher order aberrations may be decreased by creating an optimized transition zone and may be result in improving postoperative visual performance, but they cannot be eliminated.

Subjective through-focus quality of vision with various versions of modified monovision

Background/aimsTo evaluate and compare the effect of various modified monovision on binocular through-focus quality of vision.MethodsSimulated images were computed using a numerical eye model, with a 4.7 mm pupil diameter,...

Modelling the effects of secondary spherical aberration on refractive error, image quality and depth of focus.

To examine the role of Zernike secondary spherical aberration and its component terms on refraction, image quality and depth of focus. Computational methods were used to define wavefronts with controlled levels of r(6) , r(4) and r(2) terms, and image quality associated with these terms for a range of target vergences. Target vergences that generated maximum image quality were used as an objective measures of refractive error. Unlike primary Zernike spherical aberration, which generates peak image quality with a near paraxial focus, in the absence of other higher order aberrations, peak image quality with secondary spherical aberration is achieved with a near marginal focus. When alone, positive primary and secondary spherical aberration induce small hyperopic shifts in refraction, but in the presence of other higher order aberrations, secondary spherical aberration can induce significant myopic shifts in refractive error, as predicted by the combined lower order r(4) & r(2) component of Z60. The predicted expansion in depth of focus associated with increased primary or secondary spherical aberration is mostly absent if a strict image quality criterion is applied. The expansion of depth of focus observed with a low image quality criterion when opposite sign Z40 and Z60 are combined is primarily due to the elevated r(4) term. Secondary Zernike spherical aberration can have a significant impact on refractive error, image quality and depth of focus, but mostly due to the lower order components within this polynomial. Our analysis shows that the r(6) term that defines secondary spherical aberration actually narrows rather than expands depth of focus, when in the presence of the r(4) term within Z60. Therefore, a multifocal lens generated with exclusively primary spherical aberration is likely to be more effective than one that includes opposite sign of primary and secondary spherical aberration.

Robust source and mask optimization compensating for mask topography effects in computational lithography.

Mask topography effects need to be taken into consideration for a more accurate solution of source mask optimization (SMO) in advanced optical lithography. However, rigorous 3D mask models generally involve intensive computation and conventional SMO fails to manipulate the mask-induced undesired phase errors that degrade the usable depth of focus (uDOF) and process yield. In this work, an optimization approach incorporating pupil wavefront aberrations into SMO procedure is developed as an alternative to maximize the uDOF. We first design the pupil wavefront function by adding primary and secondary spherical aberrations through the coefficients of the Zernike polynomials, and then apply the conjugate gradient method to achieve an optimal source-mask pair under the condition of aberrated pupil. We also use a statistical model to determine the Zernike coefficients for the phase control and adjustment. Rigorous simulations of thick masks show that this approach provides compensation for mask topography effects by improving the pattern fidelity and increasing uDOF.

Comparison of aberrations after standard and customized refractive surgery

To detect possible differences in residual wavefront aberrations between standard and customized laser refractive surgery based onmathematical modeling, the residual optical aberrations after conventional and customized laser refractive surgery were compared accordingto the ablation profile with transition zone. The results indicated that ablation profile has a significant impact on the residual aberrations.The amount of residual aberrations for conventional correction is higher than that for customized correction. Additionally, the residualaberrations for high myopia eyes are markedly larger than those for moderate myopia eyes. For a 5 mm pupil, the main residual aberrationterm is coma and yet it is spherical aberration for a 7 mm pupil. When the pupil diameter is the same as optical zone or greater, themagnitudes of residual aberrations is obviously larger than that for a smaller pupil. In addition, the magnitudes of the residual fifth orsixth order aberrations are relatively large, especially secondary coma in a 6 mm pupil and secondary spherical aberration in a 7 mm pupil.Therefore, the customized ablation profile may be superior to the conventional correction even though the transition zone and treatmentdecentration are taken into account. However, the customized ablation profile will still induce significant amount of residual aberrations.

Quality of vision with traditional monovision versus modified monovision

AbstractPurpose To compare binocular subjective quality of vision with modified monovision (MMV) (ie different combinations of spherical (SA4) and secondary spherical (SA6) aberration on each eye) versus traditional monovision (TMV) with different level of anisometropiaMethods A numerical eye model was used to generate images (ie three 0.4 logMAR high contrast letters) viewed through a 4.7mm pupil, degraded by various condition of SA and for proximities from ‐5D to 5D (Naked eye, SA4‐0.4μm, SA4+0.4μm, SA4‐0.4 and SA6+0.2μm, SA4+0.4 and SA6‐0.2μm). Binocular vision was simulated using a 3D‐NVIDIA video device projecting different image on each eye. Binocular through‐focus (TF) quality of vision was evaluated using a grading scale (ITU‐R 500 recommendation) by four subjects with TMV for different level of anisometropia (ie 0.5 to 3D at 0.5D step) and with various combination of MMVResults Area under TF curve (ie a way to evaluate quality of vision) measured for a fair or higher image quality was increased with TMV and MMV compared to naked eye because of the summation of the two best monocular curves. With TMV, a 2.5D anisometropia was the more effective to increase area under TF curve with however a lack of intermediate vision. With MMV the greatest increase of quality of vision was obtained with reverse profile of SA4 and SA6 on each eye (ie SA4‐0.4 and SA6+0.2μm on one eye and SA4+0.4 and SA6‐0.2μm on the other eye). Compared to TMV, reverse profiles of MMV showed a significant benefit in improving area under TF curve thanks to a better quality of intermediate visionConclusion MMV especially with reverse profiles of SA improved overall quality of vision without the lack of intermediate quality of vision intermediate quality of vision induced by TMV

Visual and Physiological Optics

Visual and Physiological Optics

Measurement and prediction of subjective gradations of images in presence of monochromatic aberrations

The three objectives of this study were (i) to explore the effect of various levels of aberrations on subjective vision by scoring images, (ii) to compare subjective scores obtained with real optics and simulated images and (iii) to test the ability of image quality metrics to predict these scores. In a first experiment, 14 subjects evaluated the quality of images degraded by 0.05, 0.1, 0.2, 0.4 and 0.8μm of defocus, astigmatism, trefoil, coma, spherical aberration (SA4) and secondary spherical aberration (SA6) by putting a mark on a 5-items continuous grading scale. The desired aberration was introduced either by a deformable mirror or by displaying a simulated image. In the second experiment, 5 of the previous subjects evaluated the quality of through-focus images in presence of SA4, SA6 and combinations of SA4 and SA6. Both experiments were performed with an artificial pupil of 6mm diameter. The addition of increasing amounts of aberrations reduced the subjective grading of the targets, with SA6, SA4 and defocus being the most degrading aberrations. The correlation between the results obtained with the AO device and with simulated images gave a r(2) of 0.95. Combinations of 0.4μm of SA4 and 0.2μm of SA6 of opposite signs induced a bimodal through-focus image score curve. We were able to anticipate the subjective gradation of subject's vision thanks to image quality metrics (r(2)=0.92). Image quality score shows similar results as that obtained by objective image quality metrics, which provides a useful tool for optical designers and practitioners.