Residual Spherical Aberration Research Articles

Understanding the limits of remote focusing.

It has previously been demonstrated in both simulation and experiment that well aligned remote focusing microscopes exhibit residual spherical aberration outside the focal plane. In this work, compensation of the residual spherical aberration is provided by the correction collar on the primary objective, controlled by a high precision stepper motor. A Shack-Hartmann wave front sensor is used to demonstrate the magnitude of the spherical aberration generated by the correction collar matches that predicted by an optical model of the objective lens. The limited impact of spherical aberration compensation on the diffraction limited range of the remote focusing system is described through a consideration of both on-axis and off-axis comatic and astigmatic aberrations, which are an inherent feature of remote focusing microscopes.

Effect of larger corneal spherical aberration in improving the near visual acuity of eyes implanted with the TECNIS Symfony.

To explore the effect of corneal spherical aberration on the visual acuity and visual quality of eyes implanted with the TECNIS Symfony intraocular lens (IOL). A total of 43 patients with age-related cataract (60 eyes) undergoing phacoemulsification and TECNIS Symfony IOL implantation were enrolled in this study. The uncorrected distance (UDVA), intermediate (UIVA), near visual acuity (UNVA), corrected distance visual acuity (CDVA), contrast sensitivity, and ocular spherical aberration were recorded 3 months after surgery. Preoperative and postoperative corneal spherical aberration were also measured using the iTrace device. Objective scattering index (OSI), modulation transfer function cut-off frequency (MTF cut-off), and Strehl ratio (SR) were measured by the Optical Quality Analyzing System. Catquest-9SF questionnaire were applied too. Spearman's correlation analysis was used to evaluate the relationship between spherical aberration and visual quality parameters. Patients were satisfied with their postoperatively visual quality. And the postoperative logMAR UDVA, UIVA, UNVA, and CDVA was 0.05 ± 0.07, 0.04 ± 0.06, 0.15 ± 0.07, and 0.03 ± 0.05, respectively. The mean preoperative corneal spherical aberration was 0.24 ± 0.10 μm, which is the only factor influencing postoperatively UNVA, and it was negatively correlated with UNVA and glare contrast sensitivity under 18 cpd (cycle/degree, cpd) spatial frequency (r = -0.403, -0.300, -0.360; all P < 0.05). Additionally, the greater the residual spherical aberration of the cornea, the better the near vision after operation. The mean postoperative ocular spherical aberration was -0.03 ± 0.07 μm, it was not correlated with visual acuity, contrast sensitivity, and visual quality (all P > 0.05). Preoperative positive spherical aberration can benefit near vision while decrease contrast sensitivities at high spatial frequencies when implanted with the TECNIS Symfony IOL.

Sensitivity of remote focusing microscopes to magnification mismatch.

Remote focusing (RF) is a technique that greatly extends the aberration-free axial scan range of an optical microscope. To maximise the diffraction limited depth range in an RF system, the magnification of the relay lenses should be such that the pupil planes of the objectives are accurately mapped on to each other. In this paper we study the tolerance of the RF system to magnification mismatch and quantify the amount of residual spherical aberration present at different focusing depths. We observe that small deviations from ideal magnification results in increased amounts of residual spherical aberration terms leading to a reduction in the diffracted limited range. For high-numerical aperture objectives, the simulation predicts a 50% decrease in the diffracted limited range for 1% magnification mismatch. The simulation has been verified against an experimental RF system with ideal and nonideal magnifications. Experimentally confirmed predictions also provide a valuable empirical method of determining when a system is close to the ideal phase matching condition, based on the sign of the spherical aberration on either side of focus.

Could the percent tissue altered (PTA) index be considered as a unique factor in ectasia risk assessment?

To evaluate the efficacy, safety, predictability and stability of the percent tissue altered (PTA) formula in post-LASIK (laser-assisted in situ keratomileusis) ectasia risk assessment. One hundred and ninety-three eyes from 104 patients with low to moderate myopia that underwent femtosecond LASIK were included in this retrospective, observational and longitudinal study. Seventy-eight eyes were classified in the higher-PTA (> 40%) group and 115 eyes in the lower-PTA (< 40%) group. Spherical manifest refraction, cylinder manifest refraction, logMAR and Snellen previous corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), anterior face Baiocchi Calossi Versaci index (BCVf) and posterior face (BCVb), central corneal thickness (CCT), estimated residual stromal bed (RSB), spherical aberration (SA) and root mean square (RMS) were reported. All patients were followed up for 4years. In the higher-PTA group, 97% of eyes reported UDVA 20/20 or better, and in the lower-PTA group, all eyes achieved 20/20 or better. No group reported decreased visual acuity. The higher-PTA group obtained 55% of eyes within ± 0.50 D and 90% within ± 1.00 D; and the lower-PTA group obtained 63% of eyes within ± 0.50 D and 90% within ± 1.00 D. Both groups showed a refraction correction of 0.50 D or more in 36% and 31% of eyes, in the higher-PTA and the lower-PTA groups, respectively. Percent tissue altered index should not be considered as a unique variable in post-LASIK ectasia risk assessment. Ectasia susceptibility screening should integrate tomography and biomechanical variables in order to help us to decide any refractive treatment choice and increasing refractive surgery safety.

Pupillodynamics and corneal spherical aberrations in a set of Indian cataract patients and its implications for aberrometric customisation of intraocular lenses.

Purpose:Assessment of pupil diameter in various light conditions and the corresponding corneal spherical aberrations in a cohort of Indian eyes with bilateral senile cataracts and the possible use of this data in aberrometric customization of intraocular lenses (IOLs).Methods:In this prospective observational study done at a tertiary eye care centre in India, the selected patients were subjected to measurement of their pupil diameters in scotopic, mesopic, and photopic conditions as well as the corresponding corneal spherical aberrations, using the Sirius Topographer (Costruzione Strumenti Oftalmici, Florence, Italy). Shapiro–Wilk test, Independent t-test, ANOVA with Bonferroni correction on post-hoc testing were used for statistical analysis.Results:104 eyes of 52 patients were enrolled for the study. The mean age was 53 ± 11.88 years. The mean scotopic, mesopic, and photopic pupil sizes were 4.37 mm (4.11–4.63 mm), 3.92 mm (3.71 mm–4.15 mm), and 3.37 mm (3.18–3.67 mm), respectively. There was a statistically significant difference (P = <0.001) in the mean corneal spherical aberration measured at the 6 mm zone (0.23 ± 0.02 microns) and at the 4 mm zone (0.06 ± 0.01 microns).Conclusion:The mean corneal spherical aberration corresponding to the average mesopic pupil size of our patient population was substantially lower than that of the scotopic pupil size and also less than the amount corrected by most of the negative aspheric IOLs. This perhaps indicates the need for customising IOLs based on the spherical aberrations of cornea at the zone corresponding to the mesopic pupil diameter for optimal residual total postoperative spherical aberrations.

Experimental validation of hybrid optical–digital imaging system for extended depth-of-field based on co-optimized binary phase masks

We experimentally investigate the performance of co-optimized hybrid optical-digital imaging systems based on binary phase masks and digital deconvolution for extended depth-of-field (DoF) under narrow-band illumination hypothesis. These systems are numerically optimized by assuming a simple generic imaging model. Using images of DoF targets and real scenes, we experimentally demonstrate that in practice, they actually reach the DoF range for which they have been optimized. Moreover, they are shown to be robust against small mask manufacturing errors and residual spherical aberration in the optical system. These results demonstrate that the optical/digital optimization protocol based on generic imaging model can be safely used to design DoF-enhanced imaging systems aimed at real-world applications.

Analysis of the corneal spherical aberration in patients with primary angle-closure glaucoma with cataract

Objective To analyze the distribution and related factors of the spherical aberration in patients with primary angle-closure glaucoma and cataract. Methods Retrospective series of case study. The data of 154 eyes of 120 patients of primary angle-closure glaucoma with cataract from Nov. 2018 to Mar. 2019 in this hospital were analyzed. Pentacam HR anterior segment analyzer (Oculus, Germany) was used to measure and analyse datas. Results The average age of patients was (68.00±9.95) years, ranged from 33 to 85 years. The average spherical aberration was (0.35±0.16) μm, ranged from -0.35 μm to 0.76 μm. A positive correlation was found between spherical aberration and age(r=0.287, P=0.000), spherical aberration and mean corneal refractive power(r= 0.170, P=0.035). A negative correlation was found between spherical aberration and corneal refractive power of posterior surface(r=-0.164, P=0.042). There were no correlation between spherical aberration and corneal diameter, corneal thickness, corneal volume and axis length(r=-0.034, -0.149, -0.126, -0.123, P=0.681, 0.066, 0.119, 0.134). With residual spherical aberration(0.1±0.05)μm as the target, 90 eyes (58.4%) were corrected by different aspheric IOLs(0, -0.20 μm, -0.27 μm). Conclusion Corneal spherical aberration in patients with primary angle-closure glaucoma and cataract is larger than that reported in other populations(+ 0.27 μm), and with larger fluctuation range. A suitable IOL should be selected according to the preoperative comprehensive evaluation of personalized spherical aberrations, pupil, visual field and the injury of the optic nerve. Key words: Glaucoma; Cataract; Aberration, spheric, corneal; Lens, intraocular, aspheric

Personalized aspheric intraocular lens implantation based on corneal spherical aberration: a review.

With the evolution of cataract surgery from visual rehabilitation to refractive surgery, aspheric intraocular lenses (IOLs) are being increasingly used in the field of ophthalmology. This increased use can be attributed to negative or zero spherical aberrations with unique optical designs, which counteract some of the positive spherical aberrations of the cornea. These alterations reduce the total spherical aberration of human eyes and improve the visual acuity in patients with cataract postoperatively. At present, various types of aspheric IOLs are used worldwide. Although the implantation of aspheric IOL is beneficial to the patients who need correction of spherical aberrations, much controversy is still associated with ocular residual spherical aberrations that facilitate the best visual quality for patients postoperatively. In order to provide reference for future clinical work and scientific research, this report reviews the relationship between the ocular residual spherical aberration of human eyes and visual quality.

Evaluation of Visual Quality in Pseudophakic Eyes with Different Ocular Spherical Aberrations

ABSTRACT Purpose To evaluate the effects of different residual total ocular spherical aberration (SA) on objective and subjective visual quality in pseudophakic eyes. Methods This prospective consecutive study comprised 171 patients with age-related cataract and undergone unilateral uneventful phacoemulsification. All participants were divided into four groups based on residual ocular SA at 6 mm pupil: negative SA (≤−0.10 μm, group A), neutral SA (0.00 ± 0.05 μm, group B), slightly positive SA (0.10 ± 0.05 μm, group C), and more positive SA (0.20 μm, group D), respectively. Subjective visual acuity and contrast sensitivity, and objective optical quality and ocular aberrations were analyzed 3 months postoperatively. Results There was no significant difference in baseline measurements across all groups. Postoperatively, no statistically significant differences were found in visual acuity between groups (P > .05), while differences reached statistical significance in mesopic contrast sensitivity at 12 and 18 cpd (P < .01). There were significant differences in ocular SA and higher-order aberrations at 6 mm pupil, as well as in optical quality parameters (P < .05). Group C showed a minimum value of objective scatter index (1.17 ± 0.55) but maximum values of modulation transfer function cutoff (31.94 ± 9.18) and optical quality value OV 100% (1.07 ± 0.31), indicating lower intraocular scattering and superior optical quality. Conclusions This comprehensive evaluation is conducive to deepening the understanding of visual and optical performance of pseudophakic eye. A modest amount of positive ocular SA seemed to be a more preferable option for enhancing visual quality after aspheric ntraocular lense (IOL) implantation.

Effects of decentration and tilt on the optical performance of 6 aspheric intraocular lens designs in a model eye

To compare the effect of decentration and tilt on the optical performance of 6 aspheric intraocular lens (IOL) designs in a model eye. Department of Ophthalmology, Graduate School of Medicine, Dokkyo Medical University, Tochigi, Japan. Experimental study. In theoretical simulations, the amount of spherical aberration in the IOL was varied to produce residual ocular spherical aberration (range -0.15 to 0.30μm) at a 6.0mm entrance pupil. Wavefront aberration analyses were performed with the ZEMAX optical design program (version August 20, 2014) to obtain the ocular root-mean-square values of astigmatism, coma, trefoil, and higher-order aberrations (HOAs) when the IOL was centered on the insertion position and misaligned at a 4.0mm entrance pupil. The retinal visual images were calculated using the same conditions. Six 20.0 diopter (D) aspheric IOLs and one 20.0 D spherical IOL were used for the experimental studies. Each IOL was inserted in the model eye. The actual alignments were measured using a Scheimpflug camera (EAS-1000). The wavefront aberrations and visual images were gauged using a wavefront analyzer (KR-1W) at several IOL alignments. Intraocular lens decentration and tilt increased wavefront aberrations and degraded optical performance. Astigmatism, coma, and HOAs generated by misaligned IOLs were related to the amount of spherical aberration correction of the IOLs. The extent of spherical aberration remained unchanged by the amount of misalignment. Experimental model eye results showed trends similar to theoretical results. The spherical aberration correction amount in the aspheric IOL design was critical for the astigmatism, coma, and HOAs generated by the IOL misalignment. Additional spherical aberration corrections led to a more sensitive optical performance degradation resulting from IOL misalignment.

First results with a new intraocular lens design for the individual correction of spherical aberration

To assess the feasibility of individual compensation of corneal spherical aberration with a custom intraocular lens (IOL). Department of Ophthalmology, Rudolf Virchow Klinikum Glauchau, Glauchau, Germany. Prospective case series. Cataract patients were randomized to receive an individual aberration-correcting IOL (Invidua-aA; Group A) or a standard aspheric aberration-free IOL of otherwise identical design (Aspira-aA; Group B). In Group A, the IOL was designed according to preoperative calculation of the corneal spherical aberration Z(4,0). The aim was to achieve an overall postoperative ocular spherical aberration close to zero. Four weeks and 3months postoperatively, the refraction, visual acuity (far, intermediate, and near distance), photopic and mesopic contrast sensitivities (with and without glare), defocus curve, corneal and ocular spherical aberration, and pupil size were measured. Group A, 57 eyes of 42 patients and Group B, 29 eyes of 27 patients. Preoperatively, there was no difference in corneal spherical aberration between groups (P>.05). Three months postoperatively, residual ocular spherical aberration Z(4,0) was significantly lower in Group A (P<.001). Photopic and mesopic contrast sensitivities (with and without glare) were significantly higher in Group A at most spatial frequencies. Monocular defocus curve and distance, intermediate, and near visual acuity outcomes did not differ significantly between groups. Implantation of a custom monofocal aspheric IOL effectively reduced overall ocular spherical aberration. Clinical outcomes indicate that IOLs with an individual spherical aberration correction improve functional vision, especially contrast sensitivity, compared with standard aberration-free IOLs.

Clinical observation of visual quality after the individual implantation of intraocular lens guided by corneal Q value

Objective: To describe the feasibility of individual IOL implantation guided by corneal Q value and observe patients postoperative visual quality under different residual spherical aberration. Methods: Prospective study. One hundred and twenty cases (171 eyes)cataract patients in our hospital were selected for the individual implantation of intraocular lens guided by corneal Q value which obtained by Oberscan before operation. Based on spherical aberration calculated by corneal Q value, choose appropriate IOL personalitily to make postoperative whole eye surface aberration +0.1 μm (group of positive spherical aberration) or 0 μm (group of zero spherical aberration). To observe spherical aberration, the uncorrected visual acuity, best corrected visual acuity and contrast sensitivity (including no glare and glare) 1 month and 3 months after surgery. Dates were analyzed with one-way ANOVA and LSD method for multiple comparisons between groups. Results: Spherical aberration after operation: group of positive spherical aberration: (0.111±0.023)μm, group of zero spherical aberration: (0.020±0.019)μm, control group: (0.299±0.073)μm. At 1 months and 3 months, uncorrected visual acuity, and corrected visual acuity were not statistically different between groups (t=0.474, 1.607, P>0.05). Contrast sensitivity (including no glare and glare) 3 months after surgery display: at whole space frequency, the group of positive spherical aberration(reserved +0.1 μm spherical aberration) contrast sensitivity is better than that of the group of zero spherical aberration(reserved 0.0 μm spherical aberration) and the control group(F=32.885, 35.493, 19.969, 20.572,P<0.05). The group of zero spherical aberration is better than control group at space frequency of 3 and 6 c/d(F=6.506, 7.521, P<0.05). Conclusions: The individual implantation of introcular lens guided by corneal Q value is feasible. + 0.1 μm spherical aberration after surgery can achieve the best contrast sensitivity and stereo vision, and 0 spherical aberration after surgery can improve the postoperative contrast sensitivity and stereo vision than a traditional method, but its advantage mainly embodies in the middle and lower spatial frequency. (Chin J Ophthalmol, 2017, 53: 814-820).

The efficiency of aspheric intraocular lens according to biometric measurements.

PurposeTo analyze internal spherical aberration in pseudophakic eyes that underwent aspheric intraocular lens (IOL) implantation, and to investigate the relationships between biometric data and the effectiveness of aspheric IOL implantation.MethodsThis retrospective study included 40 eyes of 40 patients who underwent implantation of an IOL having a negative spherical aberration of -0.20 μm (CT ASPHINA 509M; Carl Zeiss Meditec Inc., Germany). The IOLMaster (version 5.0; Carl Zeiss AG, Germany) was used for preoperative biometric measurements (axial length, anterior chamber depth, central corneal power) and the measurement of postoperative anterior chamber depth. The spherical aberrations were measured preoperatively and 3 months postoperatively using the iTrace (Tracey Technologies, Houston, TX, USA) at a pupil diameter of 5.0 mm. We investigated the relationships between preoperative biometric data and postoperative internal spherical aberration, and compared biometric measurements between 2 subgroups stratified according to internal spherical aberration (spherical aberration ≤ -0.06 μm vs. spherical aberration > -0.06 μm).ResultsThe mean postoperative internal spherical aberration was -0.087 ± 0.063 μm. Preoperative axial length and residual total spherical aberration showed statistically significant correlations with internal spherical aberration (p = 0.041, 0.002). Preoperative axial length, postoperative anterior chamber depth, IOL power, and residual spherical aberration showed significant differences between the 2 subgroups stratified according to internal spherical aberration (p = 0.020, 0.029, 0.048, 0.041 respectively).ConclusionThe corrective effect of an aspheric IOL is influenced by preoperative axial length and postoperative anterior chamber depth. Not only the amount of negative spherical aberration on the IOL surface but also the preoperative axial length should be considered to optimize spherical aberration after aspheric IOL implantation.

Optical system of an objective with a conical plate

It is shown that, when the residual spherical aberration exceeds the allowable value and there is screening of the central zone of pencils of light rays, the image of a point in a plane displaced relative to its nominal position has the form of a ring. Supplementing the system with a plate having a conical surface makes it possible to transform the ring into a circle with a diameter equal to the width of the ring. A method is considered for the parametric synthesis of such a system.

Custom selection of aspheric intraocular lens in eyes with previous hyperopic corneal surgery

To determine the optimum amount of spherical aberration in intra-ocular lenses (IOLs) to maximize optical quality in eyes with previous hyperopic corneal surgery. Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. Theoretical simulation study. The amount of spherical aberration in the IOL was varied to produce residual ocular spherical aberration ranging from -0.50 to +0.50 μm. With the use of the Zernike Tool Program, the polychromatic point-spread function with Stiles-Crawford effect was calculated for 6.0 mm and 4.0 mm pupils and defocus of 0.00 diopter (D), -0.50 D, and +0.50 D. The IOL spherical aberration at which maximum image quality was achieved was determined. Stepwise multiple regression analysis was performed to assess the predictors of optimum IOL spherical aberration. Aspheric IOL implantation was simulated in 106 eyes of 80 patients; ages ranged from 40 to 59 years. With 0.00 D, -0.50 D, and +0.50 D defocus, respectively, the ranges of 25th to 75th percentiles of the optimum IOL spherical aberration were -0.12 to +0.20 μm, +0.10 to +0.42 μm, and -0.35 to -0.03 μm for the 6.0 mm pupil and -0.14 to +0.26 μm, +0.41 to +0.86 μm, and -0.74 to -0.24 μm for the 4.0 mm pupil. The amount of optimum IOL spherical aberration could be predicted on the basis of other higher-order aberrations (HOAs) of the cornea with multiple correlation coefficients up to 0.98. The amount of IOL spherical aberration producing the best image quality in eyes with previous hyperopic corneal surgery varied widely and could be predicted on the basis of the full spectrum of corneal HOAs. Supported in part by an unrestricted grant from Research to Prevent Blindness, New York, New York. No author has a financial or proprietary interest in any material or method mentioned.

Simulated prototype of posterior chamber phakic intraocular lens for presbyopia correction

To evaluate the visual impact of adding different spherical aberration values to an Implantable Collamer Lens phakic intraocular lens (pIOL) to increase the depth of focus using an adaptive optics visual simulator. University of Valencia, Valencia, Spain. Experimental study. Wavefront aberrations in -3.00 D and -6.00 diopter (D) pIOLs were measured in vitro. Afterward, different simulated pIOL experimental prototypes were created along with variances in the spherical aberration. An adaptive optics visual simulator was used to simulate vision after the implantation of the different pIOL prototypes from their wavefront aberrations. The corrected distance visual acuity (CDVA) and depth of focus were measured in 3.0 and 4.5 mm pupils. In a 3.0 mm pupil, the CDVA achieved with -3.00 and -6.00 D pIOLs and all pIOL prototypes evaluated was above 20/20 except for a -6.00 D pIOL + spherical aberration 4 at 50% CDVA contrast, which decreased to 20/25. However, in a 4.5 mm pupil, the CDVA obtained with the pIOL prototypes decreased significantly and was more pronounced when the spherical aberration induced was negative. The depth of focus increment was larger with the highest spherical aberration added and with a small pupil. Nevertheless, it was independent of the sign of the added spherical aberration. The outcomes show that residual negative spherical aberration after pIOL implantation will disrupt the CDVA. However, some residual positive spherical aberration after pIOL implantation increased the depth of focus with excellent CDVA, providing a possible pIOL design for young presbyopic patients. No author has a financial or proprietary interest in any material or method mentioned.

Clinical study of customized aspherical intraocular lens implants.

To compare if there is an improvement in visual functions with age-related cataracts between patients receiving a aspherical intraocular lens (IOL) based on corneal wavefront aberration and patients randomly assigned lenses. A total of 124 eyes of 124 patients with age-related cataracts were placed in experimental group and a group receiving randomly assigned (RA) lenses. The experimental group was undergone Pentacam corneal spherical aberration measurement before surgery; the targeted range for residual total spherical aberration after surgery was set to 0-0.3 µm. Patients with a corneal spherical aberration <0.3 µm were implanted with a zero-spherical aberration advanced optics (AO) aspherical IOL and patients with an aberration ≥0.3 µm received a Tecnis Z9003 aspherical lens in experimental group. RA patients were randomly implanted with an AO lens or a Tecnis Z9003 lens. Three months after surgery total spherical aberration, photopic/mesopic contrast sensitivities, photopic/mesopic with glare contrast sensitivities, and logMAR vision were measured. Statistical analysis on logMAR vision showed no significant difference between two groups (P=0.413). The post-surgical total spherical aberration was 0.126±0.097 µm and 0.152±0.151 µm in the experimental and RA groups, respectively (P=0.12). The mesopic contrast sensitivities at spatial frequencies of 6, 12 and 18 c/d in the experimental group were significantly higher than of the RA group (P=0.00; P=0.04; P=0.02). The mesopic with glare contrast sensitivity in the experimental group at a spatial frequency of 18 c/d was also significantly higher vs the RA group (P=0.01). Pre-surgical corneal spherical aberration measurement in cataract patients followed by customized selection of aspherical IOL implants improved mesopic contrast sensitivities at high spatial frequencies, and thus is a superior strategy compared to the random selection of aspherical IOL implants.

Total spherical aberration of the cornea in patients with cataract.

To investigate the distribution of corneal spherical aberration in patients with cataract using the Pentacam HR. Consecutive cataract patients were examined using the Pentacam HR high-resolution rotating Scheimpflug camera (Oculus, Wetzlar, Germany). In one eye of each patient, the root-mean-square (RMS) of anterior, posterior, and total corneal spherical aberration Z4(0) was calculated by ray-tracing on an area of 6 mm diameter. The Pearson correlation coefficient (r) was used to assess correlations between Z4(0) RMS values and age/total corneal refractive power. The χ2 test was used to compare the proportion of eyes qualifying for spherically neutral or negatively aspheric (-0.17 and -0.27 μm) intraocular lenses (IOLs) by targeted level of residual spherical aberration. Fifty-seven men and 92 women were included (mean [±SD] age, 71.73 [±9.12] years). The RMS mean (±SD) values of Z4(0) were +0.353 (±0.132) μm, -0.121 (±0.034) μm, and +0.328 (±0.132) μm, respectively, for the anterior, posterior, and total cornea. The anterior, posterior, and total Z4(0) were on average significantly higher (p < 0.001) in women than in men. In both sexes, statistically significant (p < 0.05) age-related changes were found for the anterior and total Z4(0) but not for the posterior Z4(0) (p > 0.05). The total Z4(0) and total corneal refractive power were significantly correlated in men (p = 0.01) but not in women (p = 0.14). For postoperative targets of 0 ± 0.05/+0.10 ± 0.05 μm residual Z4(0), the proportion of eyes that would have qualified for implantation of negatively aspheric IOLs with -0.17 and with -0.27 μm was similar (61.1 and 56.3%, respectively; p = 0.09); significantly fewer eyes (6.7%) would have qualified for implantation of neutrally aspheric IOLs (p > 0.05). Total corneal Z4(0) measured by Pentacam HR might be higher than that reported in previous studies. In most patients, the implantation of commercially available negatively aspheric IOLs would partially compensate for the positive total corneal Z4(0).

Spherical aberration: Friend or foe?

AbstractTo determine the level of residual spherical aberration that gives the best objective and subjective quality of image after cataract surgery with intraocular lens (IOL) implantation. Six months after microincision (1.8 mm) cataract surgery with aspheric IOL implantation, total aberrations were computed using a Wavescan aberrometer. The modulation transfer function (MTF), Strehl ratio, and objective index of scattering were measured using the Objective Quality Analysis System. Objective depth of focus was computed as the focus range at which the Strehl ratio did not fall below 50% of maximum. Subjective depth of focus was calculated as the difference between the vergence of the punctum remotum and that of the punctum proximum. Thirty patients (54 eyes) were evaluated. The MTF cutoff values were higher with decreasing total ocular spherical aberration (r = 0.56; P&lt;.05). Objective and subjective depth of focus were positively correlated with total spherical aberration (r = 0.26 and r = 0.46, respectively; P&lt;.05). A final spherical aberration of zero obtained by compensation of IOL asphericity gave the greatest improvement in objective quality of vision and better MTF contrast. However, a final target ocular spherical aberration between 0.07 μm and 0.10 μm should be considered to be the best compromise between subjective depth of focus and objective contrast sensitivity.

Visual simulation through an aspheric aberration‐correcting intraocular lens in subjects with different corneal profiles using adaptive optics

BackgroundThe aim of this study was to analyse the visual quality of the AcrySof IQ SN60WF® intraocular lens (IOL) when combined with different corneal profiles.MethodsTen eyes of 10 participants with no prior history of refractive or cataract surgery were evaluated. An adaptive optics visual simulator was used to simulate the wavefront aberration pattern of an aspheric aberration‐correcting IOL (AcrySof IQ SN60WF ®). Normal corneas (group A), low and high myopic corneal ablations (groups B and C, respectively) and low and high hyperopic corneal ablations (groups D and E, respectively) were also simulated. Monocular distance visual acuities at 100, 50 and 10 per cent of contrast were measured.ResultsAt 100, 50 and 10 per cent contrast, no differences were found between groups A and B (p > 0.06 for all contrasts). Group A obtained better values than groups C, D and E for all contrasts (p = 0.031, p = 0.038, p = 0.032 at 100, 50 and 10 per cent of contrast, respectively). At the same time, group B obtained better values than groups C, D and E (p = 0.041, p = 0.042, p = 0.036 at 100, 50 and 10 per cent of contrast, respectively). Within the five groups, the worst results were always obtained for group E (p = 0.017, p = 0.021 and p = 0.025 at 100, 50 and 10 per cent of contrast, respectively).ConclusionsThe results suggest that the aspheric aberration‐correcting IOL studied provides comparable results, when it is combined with normal corneas and with corneas with simulated low myopic ablations. When negative amounts of residual spherical aberration after cataract surgery are expected to be achieved, IOLs with more positive spherical aberration should be considered.