Limitations of and Solutions to Using 6 mm Corneal Spherical Aberration and Q Value after Laser Refractive Surgery.

This study aimed to evaluate the spherical aberration (SA) in different corneal areas before and after femtosecond laser-assisted in situ keratomileusis (fLASIK) and transepithelial photorefractive keratectomy (tPRK), with the goal of identifying the limitations of and potential improvements in using SA within a 6 mm area. The study included 62 patients who underwent fLASIK and tPRK. Complete eye examinations including keratometry, corneal epithelial thickness, central corneal thickness, and topography were performed preoperatively and postoperatively. Anterior, posterior, and total corneal aberrations were measured preoperatively and three months postoperatively, with pupil diameters ranging from 2 to 8 mm. In the fLASIK group, compared to the preoperative SA, the anterior and total SA increased postoperatively in the 6 and 7 mm areas. In the tPRK group, meanwhile, the anterior and total SA of the 5 mm or larger areas increased postoperatively. An area of 6 mm or larger showed an increase in correlation with the changes in Q value and refractive correction. As the corneal SA and asphericity in the 6 mm zone cannot specifically demonstrate the status of areas smaller than 6 mm or changes in the optical zone after laser refractive surgery, comparison with normal values in various areas of the cornea is necessary.

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

Purpose: 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). Methods: 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. Results: 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). Conclusion: Preoperative positive spherical aberration can benefit near vision while decrease contrast sensitivities at high spatial frequencies when implanted with the TECNIS Symfony IOL.

Analysis of Corneal Spherical Aberrations in Chinese Bilateral Ectopia Lentis Patients.

Purpose: To analyze the anterior, posterior, and total corneal spherical aberrations (ASA, PSA, and TSA) in patients with Chinese bilateral ectopia lentis (EL). Methods: A cross-sectional study was conducted to evaluate corneal spherical aberration (CSA) using a Pentacam system at the 6-mm optical zone. Axial length, keratometry, astigmatism, and corneal asphericity were also determined. Results: This study included 247 patients (420 eyes) with a mean age of 18.1 years. The values of ASA, PSA, and TSA were 0.136 ± 0.100 µm, -0.118 ± 0.030 µm, and 0.095 ± 0.095 µm, respectively. In the EL patients with Marfan syndrome (MFS), ASA and TSA were significantly lower than in the non-MFS patients (0.126 ± 0.094 µm vs. 0.155 ± 0.107 µm, P = 0.004 for ASA; 0.085 ± 0.091 µm vs. 0.114 ± 0.099 µm, P = 0.003 for TSA), whereas PSA was not significantly different (P = 0.061). The values of ASA and TSA were significantly higher in the patients with EL aged ≥ 40 years old than in younger patients, whereas ASA and PSA were lower in patients aged <10 years old than in older patients (all P < 0.05). In the multiple linear regression analysis, age, keratometry, astigmatism, anterior asphericity, higher-order aberration (HOA), and lower-order aberration (LOA) were positively or negatively correlated with TSA in the patients with EL (r = 0.681, P < 0.001). Conclusions: Corneal spherical aberration was low in the patients with EL especially for MFS and tended to increase with aging. Preoperatively, individual measurement of CSA was necessary for bilateral EL patients with MFS.

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.

Normative Values of Corneal Spherical Aberration, Pupil Size, and Other Key Refractive and Topographic Parameters in a Large Cohort of Egyptian Cataract Surgery Candidates.

PURPOSE: To determine the spherical aberration, pupil size, and other key refractive and topographic parameters in a large cohort of Egyptian cataract surgery candidates, and to investigate any existent relations between the spherical aberration and other possibly related parameters. METHODS: This is a cross-sectional, descriptive study that was conducted at Ain Shams University Hospitals, Cairo, Egypt. The study was performed on the right eyes of 1658 cataract surgery candidates. The mean corneal spherical aberration [Z4] and the pupil diameter, both photopic [P. Pupil] and mesopic [M. Pupil], were measured by the Oculus Keratograph 3, while the white-to-white corneal diameter [WTW], average keratometric readings [average K], axial length measurements [AL] and Anterior Chamber Depth [ACD] were all obtained from the IOL Master 500. RESULTS: The mean age was 65 ± 11.3 years. The mean value of the Z4 was +0.26 ± 0.12 µm [95% Confidence Interval "CI" (0.2570-0.2681)]. The mean values of the measured parameters were: P. Pupil 2.43 ± 0.87 mm [95% CI (2.3867-2.4700)], M. Pupil 4.61 ± 0.91 mm [95% CI (4.5683-4.6557)], WTW 11.72 ± 0.44 mm [95% CI (11.6969-11.7394)], average K 43.89 ± 1.89 D [95% CI (43.7938-43.9701)], AL 24.23 ± 2.21 mm [95% CI (24.1118-24.3166)], and ACD 3.16 ± 0.43 mm [95% CI (3.1414-3.1827)]. Weak statistically significant correlations were found between the Z4 and each of age (r = 0.049, p = 0.044), average K (r = 0.191, p < 0.001), and ACD (r = 0.122, p < 0.001). Multivariate analysis showed weaker relations between Z4 and both average K (beta coefficient= 0.091) and ACD (beta coefficient= 0.130), with an r2 = 0.024. CONCLUSION: This is the first normative data report of corneal spherical aberration [Z4], pupil size, and related refractive and topographic parameters in an old Egyptian population. The detected correlations have a weak clinical relevance and negate the existence of significant relations between the Z4 and the studied refractive and topographic parameters.

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.

Comparative study of corneal spherical aberration and curvature measured by iTrace and Pentacam / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the difference and consistency between iTrace and Pentacam in measuring corneal spherical aberration(SphA)and curvature.<p>METHODS: The corneal spherical aberration and curvature were measured by iTrace and Pentacam in 63 cases(125 eyes)separately, and the SphA, the minimum corneal curvature(K1), maximum corneal curvature(K2)and corneal astigmatism(CA)were recorded respectively. Paired <i>t</i>-test was used for statistical analysis of econometric data, Bland-Altman analysis was used to evaluate the consistency of measurement results(SphA and curvature)measured by iTrace and Pentacam.<p>RESULTS: The measurement result of SphA, K1, K2 and CA were(0.230±0.086)μm,(43.01±2.38)D,(44.08±2.48)D and(1.03±0.57)D measured by iTrace, and(0.247±0.114)μm,(42.88±1.44)D,(43.86±1.51)D and(1.07±0.62)D measured by Pentacam, there was no significant difference of the measurement result of SphA, K1, K2 and CA between iTrace and Pentacam(<i>P</i>>0.05). The difference of SphA, K1, K2 and CA between iTrace and Pentacam was close to 0, the consistency was good because of the narrow 95% confidence interval.<p>CONCLUSION:There is no significant difference of the measurement result between iTrace and Pentacam, the consistency is good, and both can be used as a mutual reference in clinical.

Analysis of corneal spherical aberration in age-related cataract / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To investigate the distribution of corneal spherical aberration in age-related cataract.<p>METHODS: Retrospective study. Totally 217 cases of age related cataract(217 eyes)were collected in the Central Hospital of Kaifeng from August 2017 to August 2018. Patients were divided into 3 groups according to age: 50-60 years(63 eyes)in group Ⅰ, 61-70 years(107 eyes)in group Ⅱ, 71-80 years(47 eyes)in group Ⅲ. Pentacam anterior segment analysis was used to measure the anterior and posterior corneal K-readings. The corneal spherical aberration of anterior, posterior and total were calculated on an area of 6mm diameter by Zernike analysis and a descriptive study was used.<p>RESULTS:The Mean±SD of total corneal spherical aberration was 0.311±0.098μm for all the patients. Statically significant were found for the anterior and total corneal spherical aberration(<i>F</i>=34.434, 32.896; <i>P</i><0.05). The anterior, posterior corneal K-readings and posterior corneal spherical aberration had no correlation with age(<i>r</i>=0.040, 0.066, 0.097, <i>P</i>>0.05). The anterior and total corneal spherical aberration were positively correlated with age(<i>r</i>=0.506, 0.509, <i>P</i><0.05).<p>CONCLUSION:The total corneal spherical aberration in age-related cataract was slightly higher than that before. The anterior and total corneal spherical aberration increased with age, and then the posterior corneal spherical aberration was not.

Analysis on corneal spherical aberration in patients with cataract in Kaifeng area / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To find out the mean corneal spherical aberration and its changes with age in Kaifeng population. METHODS: A total of 466 eyes of 427 Kaifeng subjects with cataract, whose age ranged from 52 to 75 years old, were divided into three groups according to the age. All the subjects were included in measuring K-readings of cornea, the corneal anterior and posterior surfaces of the spherical aberration and the total corneal spherical aberration using Pentacam(Oculus, Germany) at the 6-mm optical zone. RESULTS:The mean corneal spherical aberration( CSA) of the whole groups was 0. 339±0. 153μm. Patients from 50 to 60 years old had CSA of 0. 322±0. 137μm, 0. 326±0.157μm was the CSA of the patients from 60 to 70 years old, while those from 70 to 80 years old have a CSA of 0.401 ± 0. 182μm. The corneal K - readings had no correlation with the total corneal spherical aberration ( r=0. 034, P>0. 05), anterior surfaces CSA, posterior surfaces and total CSA were positively correlated with age ( r =0.253, 0. 327, 0. 233, all P CONCLUSION:CSA is varied among the population and CSA of elderly in Kaifeng area are slightly higher than white people, and positively correlated with age.

Estimation of Corneal Spherical Aberration from Topography

PURPOSE: To formulate an equation to estimate corneal spherical aberration using Orbscan (Bausch & Lomb Surgical, Rochester, NY, USA) parameters. METHODS: The study was carried out retrospectively. The participants were 76 eyes of 76 senile cataract patients with the mean age of 57.37 +/- 17.63 years. Both Orbscan and KR-1W (Topcon Corp, Tokyo, Japan) were taken as preoperative examinations. Correlation analysis between various parameters from Orbscan and corneal spherical aberrations for a 6 mm pupil by KR-1W was performed. And multivariable linear regression was performed with the significantly correlated Orbscan parameters from the correlation analysis. RESULTS: The mean corneal spherical aberration from KR-1W system was 0.25 +/- 0.08 microm. As a result of the multivariable linear regression, we could generate following equations. If the Q-value was available, estimated corneal spherical aberration = 0.389 x Q-value + (0.022 x Axial power 3 mm) - 0.633 (R2 = 0.436). If the Q-value was not available, estimated corneal spherical aberration = 0.184 x (Mean power 5 mm - Mean power 3 mm) + (0.02 x Axial power 3 mm) - 0.563 (R2 = 0.429). By using the equations, 93.4-94.7% of subjects were in the error range of 0.10 microm. CONCLUSIONS: Even when equipped with Orbscan only, an appropriate aspheric intraocular lens can be selected using the estimated corneal apherical aberration by the equations.