Astigmatism In Group Research Articles

Association of myopia and astigmatism with postoperative ocular high order aberration after small incision lenticule extraction

ObjectiveTo investigate the correlation between higher-order aberrations (HOA) after small incision lenticule extraction (SMILE) and the severity of myopia and astigmatism, along with the relevant factors. These findings will provide valuable insights for decreasing the occurrence of HOA after SMILE and enhancing visual quality.MethodsA total of 75 patients (150 eyes) with myopia and astigmatism who underwent SMILE were categorized into four groups based on the severity of myopia and astigmatism: Myopia Group 1 (Group M1, spherical diopter ranged from -1.00 D to -4.00 D), Myopia Group 2 (Group M2, spherical diopter ranged from -4.10 D to -10.00 D), Astigmatism Group 1 (Group A1, cylindrical diopter ranged from 0 D to -1.00 D), and Astigmatism Group 2 (Group A2, cylindrical diopter ranged from -1.10 D to -3.00 D). A comprehensive assessment was performed to examine the association between HOA and various relevant factors, including a detailed analysis of the subgroups.ResultsGroup M1 had significantly lower levels of total eye coma aberration (CA), corneal total HOA (tHOA), internal tHOA, and vertical CA (Z3-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{Z}}}_{3}^{-1}$$\\end{document}) after SMILE than Group M2 (P < 0.05). Similarly, Group A1 had significantly lower levels of total eye tHOA, CA, trefoil aberration (TA), corneal tHOA, TA, and vertical TA (Z3-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{Z}}}_{3}^{-3}$$\\end{document}) after SMILE than Group A2 (P < 0.05). Pearson correlation analysis indicated a statistically significant positive relationship between the severity of myopia/astigmatism and most HOA (P < 0.05). Subgroup evaluations demonstrated a notable increase in postoperative HOA associated with myopia and astigmatism in Groups M2 and A2 compared with the control group. Lenticule thickness, postoperative central corneal thickness (CCT), postoperative uncorrected distance visual acuity (UDVA), and postoperative corneal Km and Cyl were strongly correlated with most HOA. Age, eyes, and postoperative intraocular pressure (IOP) were only associated with specific HOA.ConclusionHOA positively correlated with the severity of myopia and astigmatism after SMILE. However, this relationship was not linear. HOA after SMILE was influenced by various factors, and additional specialized investigations are required to establish its clinical importance.

Comparison of the new self-contained darkroom refractive screener versus table-top autorefractor and cycloplegia retinoscopy in detecting refractive error

PurposeBy comparing the results of the new self-contained darkroom refractive screener (YD-SX-A) versus table-top autorefractor and cycloplegic retinoscopy, to evaluate the performance of the YD-SX-A in detecting refractive error in children and adolescents and then judge whether it can be used in refractive screening.MethodsCross-sectional study. 1000 participants between the ages of 6 and 18 who visited the Optometry Center of the People's Hospital of Guangxi Zhuang Autonomous Region from June to December 2022 were selected. First, participants were instructed to measure their diopter with a table-top autorefractor (Topcon KR8800) and YD-SX-A in a noncycloplegic setting. After cycloplegia, they were retinoscopy by a professional optometrist. The results measured by three methods were collected respectively. To avoid deviation, only the right eye (1000 eyes) data were used in the statistical analysis. The Bland–Altman plots were used to evaluate the agreement of diopters measured by the three methods. The receiver operating characteristic (ROC) curves was used to analysis effectiveness of detecting refractive error of YD-SX-A.ResultsThe average age of participants was 10.77 ± 3.00 years, including 504 boys (50.4%) and 496 girls (49.6%). When YD-SX-A and cycloplegia retinoscopy (CR) were compared in the myopia group, there was no statistical difference in spherical equivalent (SE) (P > 0.05), but there was a statistical difference in diopter spherical (DS) and diopter cylinder (DC) (P < 0.05). Comparing the diopter results of Topcon KR8800 and CR, the difference between each test value in the myopia group was statistically significant (P < 0.05). In the hyperopia group, the comparison between YD-SX-A and CR showed no statistically significant differences in the DC (P > 0.05), but there were significant differences in the SE and DS (P < 0.05). In the astigmatism group, the SE, DS, and DC were statistically different, and the DC of YD-SX-A was lower than that of CR and Topcon KR8800. Bland–Altman plots indicated that YD-SX-A has a moderate agreement with CR and Topcon KR8800. The sensitivity and specificity of YD-SX-A for detecting myopia, hyperopia and astigmatism were 90.17% and 90.32%, 97.78% and 87.88%, 84.08% and 74.26%, respectively.ConclusionThis study has identified that YD-SX-A has shown good performance in both agreement and effectiveness in detecting refractive error when compared with Topcon KR8800 and CR. YD-SX-A could be a useful tool for large-scale population refractive screening.

Association between Central Corneal Thickness and Axial Length in Patients with Refractive Anomalies and Emmetropes

Background: This study aimed to determine the correlation between central corneal thickness (CCT) and axial length (AL) in patients with refractive anomalies and emmetropes. Methods and Results: The study included 330 respondents, with a total of 660 eyes, divided into two groups. The test group (TG) included 180 respondents with refractive anomalies (65 respondents with hypertropia, 65 with myopia, and 50 with astigmatism); the control group (CG) included 150 respondents with uncorrected visual acuity – 6/6 in both eyes. The CCT values were higher in the hypermetropic group compared to the myopic group (561.5±25.3 vs. 517.9±37.3 mm, P&lt;0.001), astigmatism group (561.5±25.3 vs. 528.3±35.3 mm, P&lt;0.001) and the CG (561.5±25.3 vs. 553.3±18.5 mm, P&lt;0.001). From 360 eyes in the TG with refractive anomalies, the lowest AL values were found in the hypermetropic group (21.7±1.0 mm) compared to the myopic group (P&lt;0.001), the astigmatism group (P&lt;0.001), and the CG (P&lt;0.001). Similar differences were also found for the right eyes (OD): hypermetrops tend to have shorter AL than the astigmatic group (P&lt;0.001), myopic group (P&lt;0.001), and the CG (emmetrope) (P&lt;0.001). Conclusion: The mean CCT value in the hyperopic group was higher than in the emmetropic group, while the CCT value of the myopic and astigmatic group was lower than that of the emmetropic group. AL values were the lowest in the hypermetropic group than in the myopic, astigmatic, and control groups.

Association Between Central Corneal Thickness and Intraocular Pressure in Patients with Refractive Anomalies and Emmetropes

Background: The aim of this study was to determine the relationship between central corneal thickness (CCT) and intraocular pressure (IOP) in patients with refractive anomalies and emmetropes. Methods and Results: This retrospective study was conducted in the Department of Ophthalmology at the University Clinical Center. The study included 330 respondents, with a total of 660 eyes, divided into two groups. The test group (TG) included 180 respondents with refractive anomalies (65 respondents with hypertropia, 65 with myopia, and 50 with astigmatism); the control group (CG) included 150 respondents with uncorrected visual acuity – 6/6 in both eyes. All respondents included in the research were aged 18–40, with an average age of 22.9 years. The values of CCT in TG was around 499.3–577.1 μm. From 360 eyes in the TG with refractive anomalies, the highest IOP values were found in the astigmatic group (20.6 mmHg) and the lowest values in the myopic group (15.3 mmHg) (P&lt;0.001) and were statistically higher compared to the CG (P&lt;0.001 in both cases). We found a statistically significant, moderate positive correlation between the values of CCT and IOP in the hypermetropic group (rs=0.655, 95% CI: 0.540 to 0.745, P&lt;0.0001) and a statistically significant low negative correlation (rs=-0.209, 95% CI: -0.373 to -0.033, P=0.0165) between the values of CCT and IOP in the myopic group. Also, a statistically significant low negative correlation (rs=-0.304, 95% CI: -0.510 to -0.152, P=0.0005) was found between the values of CCT and IOP in the astigmatism group. Conclusion: The results of our study show that increasing the CCT values in the hypermetropic group leads to an increase in the IOP values. Therefore, these findings can be used as a reference for our population, which would assist in the early diagnosis of ocular hypertension.

Spherical Aberration of Astigmatic Corneas in a Cataract Population.

To study the distribution of spherical aberration (SA) in astigmatic corneas in a cataract population and the relationship between magnitude of corneal astigmatism and fourth-order corneal SA. Data routinely collected using a Scheimpflug camera (Pentacam; Oculus Optikgeräte GmbH) were retrospectively analyzed. Patients with a minimum age of 60 years were included. Total corneal SA (from anterior and posterior corneal surface) was obtained for a 6-mm cor-neal area aligned with the pupil center. Exclusion criteria were insufficient measurement quality, total deviation index (Belin/Ambrósio Deviation) greater than 1.60, and corneal thickness at the thinnest point of less than 490 μm. One eye per patient was chosen randomly. Eyes were divided into low (≤ 1.00 diopters [D]), moderate (> 1.00 to ≤ 2.00 D), and high (> 2.00 D) astigmatism groups according to the Scheimpflug measurements. A total of 528 eyes were included in this analysis. Low astigmatism was found in 129 patients, moderate astigmatism in 265 patients, and high astigmatism in 134 patients. Mean astigmatism was 0.68 ± 0.24, 1.45 ± 0.28, and 2.91 ± 0.95 D in the low, moderate, and high astigmatism groups, respectively. Mean corneal SA in patients with moderate and high astigmatism was higher than in the low astigmatism group. The difference reached the significance level for the comparison of low and high astigmatism groups (P = .023). The fourth-order SA increased gradually with the magnitude of astigmatism with a slope of 0.015. SA was significantly larger in the cataract population with high corneal astigmatism. The increase of positive sign SA with the magnitude of astigmatism suggests that patients with moderate to high astigmatism may benefit more from intraocular lenses with negative sign SA correction. [J Refract Surg. 2023;39(8):532-538.].

Prevalence of refractive errors and visual impairment due to refractive errors among school children in Cairo, Egypt

Aim The aim of this research was to study the distribution and patterns of refractive errors (REs) among school children and the incidence of amblyopia in each type. Patients and methods This is an observational nonrandomized population-based cross-sectional study that included children aged 6-18 years attending the Outpatient Clinic of Al-Zahraa University Hospital, Al-Azhar University, Cairo, Egypt. All children were subjected to comprehensive eye examination including best corrected visual acuity (BCVA), expressed in LogMAR, cycloplegic REs that was documented using a NIDEK auto-refractometer-keratometer, cover-uncover testing, and fundus examination. The prevalence of REs, amblyopia, and anisometropia was estimated. Results The study included 960 children (1920 eyes), with a mean age of 13.08±3.41 years. Emmetropia was found in 834 (43.4%) eyes, while myopia was reported in 587 (30.6%) eyes, hypermetropia in 114 (5.9%) eyes, and myopic astigmatism in 385 (20%) eyes. Anisometropia was reported in 65 (6.77%) children, while amblyopia was found in 49 (5.1%) eyes. The amblyopia prevalence was statistically significantly higher among the hypermetropic group (3.9%) than the myopic astigmatism group (1.2%), (P = 0.031). Conclusion The overall prevalence of REs among the examined children was 56.6% mainly myopia followed by myopic astigmatism and lastly hypermetropia. This draws the attention to the increased incidence of myopia which needs further social studies.

Comparison of Refractive Outcomes and Optical Zone Decentration After SMILE Between Patients With Symmetrical and Asymmetrical High Astigmatism.

To compare the refractive outcomes and optical zone decentration between patients with symmetrical and asymmetrical high astigmatism after small incision lenticule extraction (SMILE). This was a prospective analysis of 89 patients (152 eyes) with myopia and astigmatism of more than 2.00 diopters (D) treated with the SMILE procedure. There were 69 eyes with asymmetrical topographies (asymmetrical astigmatism group) and 83 eyes with symmetrical topographies (symmetrical astigmatism group). Decentralization values were assessed using the tangential curvature difference map preoperatively and 6 months after surgery. Decentration, visual refractive outcomes, and induced changes in corneal wavefront aberrations were compared between the two groups 6 months postoperatively. Both groups achieved favorable visual and refractive outcomes, with a mean postoperative cylinder of -0.22 ± 0.23 and -0.20 ± 0.21 D in the asymmetrical and symmetrical astigmatism groups, respectively. In addition, visual and refractive outcomes and induced changes in corneal aberrations were comparable between the asymmetrical and symmetrical astigmatism groups (all P > .05). However, the total and vertical decentration in the asymmetrical astigmatism group was greater than that in the symmetrical astigmatism group (all P < .05), whereas no significant differences were found in the values of horizontal decentration between the two groups (P > .05). There was a weak positive correlation between induced total corneal higher order aberrations and total decentration (r = 0.267, P = .026) in the asymmetrical astigmatism group but not in the symmetrical astigmatism group (r = 0.210, P = .056). An asymmetrical corneal surface might affect treatment centration after SMILE. Subclinical decentration may be associated with the induction of total higher order aberrations, but it did not affect high astigmatic correction or induced corneal aberrations. [J Refract Surg. 2023;39(4):273-280.].

Corneal higher order aberrations by Sirius topography and their relation to different refractive errors

PurposeTo compare the root mean square (RMS) of anterior corneal higher-order aberrations (HOAs) in ametropic and emmetropic eyes.MethodsThis retrospective observational study was conducted at the Department of Ophthalmology, Tishreen University Hospital, Latakia, Syria. Study eyes were divided into four groups based on refractive error: mild-to-moderate myopia, hypermetropia, myopic astigmatism, and emmetropic eyes as controls. The following anterior corneal HOAs were evaluated using the Scheimpflug-Placido Sirius (CSO, Italy) tomographer over 6 mm pupil: Root mean square (RMS) total corneal HOAs, RMS trefoil, RMS coma and RMS spherical aberrations.ResultsRMS values of total HOAs, trefoil and coma showed statistically significant differences in all four groups (P < 0.05, all). HOAs were noted to be lowest in the control group (0.18 ± 0.09, 011 ± 0.08 and 0.09 ± 0.08 μm, respectively) and highest in the myopic astigmatism group (0.31 ± 0.16, 0.15 ± 0.12, 0.17 ± 0.14 μm, respectively). RMS spherical aberration was lowest in the astigmatism group (0.00 ± 0.16 μm) with a statistically significant difference from that in the control group (0.05 ± 0.07 μm, P = 0.049).ConclusionThe mean RMS values of total HOAs, trefoil and coma were highest in the astigmatism group and lowest in the control group. However, spherical aberration was minimal in the astigmatism group. A better understanding and targeted treatment of higher-order aberrations in ametropic human eyes, and in particular eyes with astigmatism, may enhance visual quality and performance in the treatment of refractive errors. Recognising atypical HOAs may also assist in the early detection of pathological conditions such as keratoconus.

Evaluation of the Effects of Myopic Astigmatism Correction and Anterior Corneal Curvature on Functional Optical Zone After SMILE.

To evaluate the influence of different degrees of myopic astigmatism correction and preoperative anterior corneal curvature on the functional optical zone (FOZ) following small incision lenticule extraction (SMILE). In this retrospective study, 68 patients (106 eyes) treated with SMILE were grouped according to myopic astigmatism correction: control (0.00 diopters [D]), moderate astigmatism (-0.50 to -2.00 D), and high astigmatism (> -2.00 D). The FOZ was measured and compared between the three groups for 3 months. Correlations between attempted correction, anterior corneal curvature, corneal aberrations, and the FOZ were analyzed. The preoperative mean treatment spherical equivalent was comparable among the three groups. The average FOZ was 5.06 ± 0.24 mm in the control group, 5.19 ± 0.25 mm in the moderate astigmatism group, and 5.35 ± 0.20 mm in the high astigmatism group The FOZ showed statistically significant differences among the three groups (P < .001), particularly between the high astigmatism group and the other two groups (P < .001 and .018). Correlation analysis showed that the total higher order aberrations, coma, and spherical aberration change were correlated with the FOZ (P < .001). Preoperative steep keratometry, average keratometry, and corneal astigmatism were significantly correlated with the FOZ (P < .05). The correlation remained after excluding the influence of attempted correction on the FOZ (P < .05). After adjusting for other risk factors using multiple linear regression analysis, there was still a significant positive association between preoperative steep keratometry and the FOZ (P < .001). Patients with higher myopic astigmatism achieved a larger FOZ and less induced horizontal coma than the control and moderate astigmatism groups. A larger FOZ after SMILE can be achieved in eyes with steeper keratometry. [J Refract Surg. 2023;39(2):135-141.].

Optical coherence tomography predictors of the outcomes of occlusion therapy in anisometropic amblyopia.

(1) To compare optical coherence tomography (OCT) parameters between amblyopic eyes and fellow eyes in patients presenting with anisometropic amblyopia. (2) To find OCT factors predicting the outcomes of occlusion therapy. This prospective study was conducted in a tertiary eye care center for a period of 20 months. Fifty-four children diagnosed with anisometropic amblyopic were included in the study. After complete ophthalmic and OCT examination, patients were advised to undergo occlusion therapy with large spectacle patch. Patients were reviewed after 6 months to record improvement in visual acuity and analyze their OCT parameters. Statistical tests used were paired "t" test and independent "t" test. The mean age of 54 study patients was 9.24 ± 2.82 years. For comparison of OCT parameters, they were classified as myopic (22 patients), hypermetropic (24 patients), and astigmatic (8 patients) groups. In the anisomyopic amblyopia group, the mean inner macular thickness was significantly increased in fellow eyes (304.09 ± 11.06 μm) compared to amblyopic eyes (297.59 ± 14.16 μm). In the anisohyperopic amblyopia group, the outer macular thickness significantly increased in amblyopic eyes (286.43 ± 18.63 μm) when compared to fellow eyes (272.62 ± 14.90 μm). In the follow-up visit, 28 patients showed improvement and 6 patients did not show improvement in final best-corrected visual acuity, and the OCT parameters in amblyopic eyes of these two groups did not differ significantly. Abnormal experience in early life does not affect the maturation process of retinal layers as evident by OCT parameters, and these parameters cannot predict the outcomes of occlusion therapy.

Effect of keratometric astigmatism on visual outcomes following small incision lenticule extraction.

To investigate the influence of keratometric astigmatism on visual outcomes following small incision lenticule extraction (SMILE). Eighty eyes undergoing SMILE for myopia correction were classified into two groups based on preoperative keratometric astigmatism: low keratometric astigmatism (LA) and high keratometric astigmatism (HA) groups. Refractive outcomes, vector components, and changes in higher order aberrations (HOAs) were evaluated preoperatively and 6 months postoperatively. At the postoperative 6-month visit, no significant difference was observed in the decentered distance between the HA and LA groups (HA: 0.17 ± 0.08 mm, LA: 0.16 ± 0.08 mm, P = 0.189). No significant differences in the correction index (P = 0.481), absolute angle of error (P = 0.104), or index of success (P = 0.147) were observed between the two groups. There was no significant difference in the induction of corneal aberrations between the two groups. Furthermore, there were no significant associations between the decentered distance and the vector components of astigmatic correction or induction of higher-order aberration in the HA group (P ≥ 0.294, P ≥ 0.112) or the LA group (P ≥ 0.323, P ≥ 0.080). SMILE for high keratometric astigmatism could achieve comparable treatment centration and visual quality to that of low keratometric astigmatism.

Effect of small-incision sutureless cataract surgery on the natural course of astigmatism over 10 to 20 years.

To retrospectively assess astigmatic changes over 10 years and 20 years after small-incision cataract surgery. 5 ophthalmic surgical sites in Japan. Retrospective case series. Data were collected from patients who had undergone phacoemulsification and implantation of an intraocular lens through a 2.2 to 2.4 mm incision. Preoperative corneal and postoperative manifest astigmatism were converted to power vector notations: horizontal/vertical (J 0 ) and oblique (J 45 ) astigmatism components. 422 eyes of 422 patients were followed for 10 years, and data preoperatively and at 1 month and at 1 year, 3 years, 5 years, 8 years, and 10 years postoperatively were analyzed. The mean J 0 decreased significantly ( P < .001, repeated measures analysis of variance) with an against-the-rule (ATR) shift of 0.363 ± 0.433 diopter (D) over 10 years, but the mean J 45 did not change significantly ( P = .150). Double-angle plot analyses also showed similar ATR shifts in all astigmatism groups. In the subgroup analysis conducted in 34 patients who were followed for 20 years, J 0 declined significantly ( P < .001) by 0.649 ± 0.576 D, whereas J 45 did not ( P = .516). The postoperative changes in J 0 and J 45 were not significantly different between eyes with preoperative with-the-rule, ATR, or oblique astigmatism. Postoperative astigmatism continued to shift toward ATR during the follow-up period of 20 years after small-incision cataract surgery, which seems to reflect the natural course of corneal astigmatic changes that commonly occur with aging. ATR astigmatic shifts were similar in both pattern and magnitude regardless of the type of preoperative astigmatism.

Levator palpebrae superioris function and corneal astigmatism in university students with normal eyelid morphology

Background: Eyelids have been shown to influence corneal shape. The effects of eyelid pathologies on corneal astigmatism have been widely investigated. This study aimed to determine the correlation between levator palpebrae superioris (LPS) muscle function and with-the-rule (WTR) corneal astigmatism in university students with normal eyelid morphology.Methods: This was a cross-sectional study with a sample of 58 university students of Chinese origin selected by simple random sampling at the University College Sedaya International (UCSI) University Optometry Clinic, Kuala Lumpur, Malaysia. We included participants aged 18 to 30 years, regardless of sex, with normal eyelid morphology, normal LPS function, and WTR corneal astigmatism. For LPS muscle function, the distance of the upper eyelid margin from the maximal downgaze to the upgaze was measured, while the frontalis function was negated by the thumb of the examiner. Corneal astigmatism was measured using a manual Keratometry (Topcon OM-4; Topcon Corporation, Tokyo, Japan). Results: Of the 58 participants, 23 (39.7%) were men and 35 (60.3%) were women. The mean ± standard deviation (SD) age was 23.22 ± 1.77 years. For all participants, the means ± SDs for LPS muscle function and corneal astigmatism were 14.72 ± 1.74 mm and - 1.16 ± 0.47 D, respectively. Of the 58 participants, 25 and 33 had low and moderate WTR corneal astigmatism, respectively. The mean LPS muscle functions were not significantly different between the low and moderate WTR corneal astigmatism groups (P &gt; 0.05). A positive but statistically insignificant correlation (r = + 0.14; P &gt; 0.05) was found between LPS muscle function and WTR corneal astigmatism. Conclusions: We found no significant difference in the mean LPS muscle function between low and moderate WTR corneal astigmatism groups in young university students of Chinese origin with normal eyelid morphology. Furthermore, no significant correlation was found between LPS muscle function and low-to-moderate WTR corneal astigmatism.

Effective Optical Zone Following Small Incision Lenticule Extraction for Myopia Calculated With Two Novel Methods.

To evaluate the effective optical zone (EOZ) following small incision lenticule extraction in myopic eyes using two novel methods and investigate factors influencing postoperative EOZ. In this prospective study, 45 patients (45 eyes) with a mean spherical equivalent of -5.82 ± 1.58 diopters underwent SMILE and were observed during a 6-month follow-up. Postoperative EOZ was calculated using custom software that automatically distinguishes EOZ on the tangential curvature difference map (EOZc) and total corneal refractive power map (EOZp) of the Pentacam HR (Oculus Optikgeräte GmbH). The agreement between the two methods, the difference between postoperative EOZ and programmed optical zone (POZ), and its relationship with parameters including corrected spheres, cylinders, ablation ratio (ablation depth/central cornea thickness), and Q-value change were investigated. The EOZc area was 20.76 ± 2.43 mm2 (diameter: 5.04 ± 0.60 mm) and the EOZp area was 20.22 ± 4.70 mm2 (diameter: 5.13 ± 0.30 mm). Both were significantly smaller than POZ (P < .001). Bland-Altman plots showed 4.44% (2/45) points located outside the 95% limits of agreement. EOZc and EOZp reductions were negatively related to corrected cylinders (r = -0.631, P < .001 and r = -0.594, P < .001, respectively). EOZp reduction was positively correlated with corrected spheres (r = 0.336, P = .024). Subgroup analysis revealed significant differences in EOZc and EOZp reduction between low and high astigmatism groups despite myopia degree. EOZ after incision lenticule extraction, measured using two novel methods, was smaller than POZ. The reduction of EOZ was negatively correlated with the corrected cylinders. [J Refract Surg. 2022;38(7):414-421.].

The influence of residual astigmatism on the postoperative visual quality in patients with implantation of an extended depth of focus intraocular lens

Objective: To investigate the influence of residual astigmatism on the postoperative visual acuity in cataract patients with implantation of an extended depth of focus intraocular lens (IOL). Methods: Retrospective cohort study. A total of 56 eyes of 56 cataract patients who underwent phacoemulsification combined with extended depth of focus IOL implantation from January 2019 to December 2020 at Eye & ENT Hospital of Fudan University were included. There were 29 males and 27 females in all patients, and the age was (65±9) years. Patients were divided into two groups according to their postoperative residual astigmatism: low astigmatism group (<0.75 D, 28 eyes) and high astigmatism group (0.75 to 1.50 D, 28 eyes). At 3 months after surgery, measurements were completed, including postoperative uncorrected distance (5 m) visual acuity, uncorrected intermediate (80 cm) visual acuity, uncorrected near (40 cm) visual acuity, best corrected visual acuity (all the visual acuity was converted to the logarithm of the minimum angle of resolution visual acuity), defocus curves, quick contrast sensitivity function, wavefront aberration, and VF-14 questionnaire scores. The independent samples t-test and Mann-Whitney U test were used for data analysis. Results: The low astigmatism group and high astigmatism group's uncorrected distance visual acuity [M (Q1, Q3)] were 0.05 (-0.06, 0.10), 0.08 (0.00, 0.22), their uncorrected intermediate visual acuity were 0.11 (0.00, 0.20), 0.14 (0.10, 0.21), their uncorrected near visual acuity were 0.28 (0.20, 0.32), 0.26 (0.20, 0.30), and their best corrected visual acuity were 0.17 (0.05, 0.30), 0.14 (0.04, 0.22), respectively. The differences were not statistically significant (all P>0.05). No significant difference was found in the defocus curves from +1.00 to -4.00 D, at intervals of +0.50 D, between the two groups (all P>0.05). No significant difference was found in the quick contrast sensitivity of low, middle and high frequency of dark vision between the low astigmatism group and high astigmatism group (all P>0.05), and the area under Log contrast sensitivity function of the two groups were 0.87±0.28 and 0.77±0.30 (P>0.05). The total whole-eye aberrations were 0.59±0.18 and 0.74±0.51, and the total higher-order aberrations were 0.30±0.13 and 0.37±0.25 in the two groups at 4.0-mm pupil diameter. The differences were not statistically significant when the total whole-eye aberration, total higher-order aberration, coma, cloverleaf aberration, and spherical aberration were compared (all P>0.05). The differences of the total VF-14 visual scores, near visual acuity scores and the distance visual acuity scores of the two groups were not statistically significant (all P>0.05). Conclusion: Cataract patients with residual postoperative astigmatism 0.75 to 1.50 D can obtain as good visual quality as those with postoperative residual astigmatism<0.75 D after implantation of an extended depth of focus IOL.

Achieved and Functional Optical Zone in Myopic Eyes With High Astigmatism After Small Incision Lenticule Extraction.

To investigate the achieved optical zone and functional optical zone in myopic eyes with high astigmatism after small incision lenticule extraction (SMILE). Seventy-five eyes of 75 consecutive patients with myopia before SMILE were included and divided into two groups (no astigmatism group: without astigmatism vs high astigmatism group: with astigmatism > 2.00 diopters). The achieved optical zone, functional optical zone, and corneal aberrations were compared using Scheimpflug imaging at 6 months postoperatively. Correlations between corneal aberrations and functional optical zone were analyzed. The mean achieved optical zone diameter was smaller in the no astigmatism group than in the high astigmatism group. There were no significant differences in achieved optical zone among the different meridians in each group. The mean functional optical zone diameter was significantly smaller in the no astigmatism group than in the high astigmatism group. Compared with the programmed optical zone, significant reduction of the functional optical zone was found in the two groups. The reduction of the functional optical zone was significantly smaller in the high astigmatism group than in the no astigmatism group, except for the 60°, 90°, and 120° meridians. There were significant correlations between the functional optical zone area and the induced corneal aberrations in the high astigmatism group, except for horizontal coma, whereas significant correlations of functional optical zone with total higher order aberrations and spherical aberration were detected in the no astigmatism group. Myopic eyes with high astigmatism following SMILE had a circular achieved optical zone, but the functional optical zone was oval and larger than in eyes without astigmatism. Moreover, a lower spherical aberration was observed in the patients with high astigmatism. [J Refract Surg. 2022;38(4):243-249.].

Evaluation of Retinal Layer Thicknesses in Patients with Keratoconus Using Retinal Layer Segmentation Analysis.

To conduct an evaluation of the effects of irregular astigmatism on the retinal nerve fiber layer (RNFL) and the retinal layers observed using spectral-domain optical coherence tomography (SD-OCT) in patients who had keratoconus (KC). A total of 255 eyes from 255 individuals, comprising 72 eyes of KC patients, 70 eyes of patients with astigmia, and 113 eyes of healthy controls were included in the analysis. RNFL scan maps (comprising global, temporal, superotemporal, inferotemporal, nasal, inferonasal, and superonasal maps) and macular thickness (MT) maps of a standard from the Early Treatment Diabetic Retinopathy Study (ETDRS) grid were assessed. The measurements were segmented automatically using Spectralis software, and included the RNFL, inner and outer plexiform layers (IPL, OPL), inner and outer nuclear layers (INL, ONL), ganglion cell layer, retinal pigment epithelium (RPE) in the central 6-mm ETDRS subfield. The RNFL thickness in the KC group was lower when compared with the other two groups; however, statistically significant differences were noted in the global, temporal, superotemporal, and inferotemporal sectors (p < 0.05 for all). All of the central MT parameters showed significant variation among the groups, while a statistically significant decrease was noted in the KC group, except in the inferior outer sector (p = 0.741). In the segmentation analysis, the KC group had the significantly lowest IPL, ONL, RPE, and outer retinal layer (ORL) thickness among the groups (p < 0.05 for each). The astigmatic group was similar to the control group with regard to these parameters (p > 0.05 for each). The eyes in the KC group appeared to have a thinner RNFL and MT when compared to those in the astigmatic and control groups. The ORLs, especially the ONL and RPE, were the most affected component of the macula in the KC group.

Comparison of long-term astigmatic changes following cataract surgery among types of corneal astigmatism

AimsTo examine whether long-term corneal astigmatic changes after stabilisation of surgically induced astigmatism (SIA) following cataract surgery differ among eyes having against-the-rule (ATR), with-the-rule (WTR), and oblique astigmatism.MethodsAnterior corneal astigmatism...

Automatic compensation enhances the orientation perception in chronic astigmatism

Astigmatism is a prevalent optical problem in which two or more focal points blur the retinal image at a particular meridian. Although many features of astigmatic vision, including orientation perception, are impaired at the retinal image level, the visual system appears to partly restore perceptual impairment after an extended period of astigmatism. However, the mechanism of orientation perception restoration in chronic astigmatism has not yet been clarified. We investigated the notable reduction of perceptual error in chronic astigmatism by comparing the orientation perception of a chronic astigmatism group with the perception of a normal-vision group, in which astigmatism was transiently induced. We found that orientation perception in the chronic group was more accurate than in the normal vision group. Interestingly, the reduction of perceptual errors was automatic; it remained even after the optical refractive errors were fully corrected, and the orientation perception was much more stable across different orientations, despite the uneven noise levels of the retinal images across meridians. We provide here a mechanistic explanation for how the compensation of astigmatic orientation perception occurred, using neural adaptation to the biased distribution of orientations.

Vector analysis of moderate to high myopic astigmatism after small-incision lenticule extraction (SMILE): 12-month follow-up.

To evaluate the refractive outcomes of small-incision lenticule extraction (SMILE) surgery in moderate to high myopic astigmatism. Prospective interventional case series. This study evaluated 111 eyes of 68 patients treated with femtosecond SMILE surgery for the correction of myopia and astigmatism. Inclusion criteria were myopia of - 0.5 D or more and astigmatism between - 1.0 D and -5.0 D. Refractive and visual measurements were obtained preoperatively, 1 and 12 month(s) postoperatively. Vector analysis was used to study the astigmatic outcomes at 12-month follow-up. Comparison of results in two groups of patients with astigmatism below and over 3.00 D was performed. The preoperative mean spherical equivalent was -5.48 ± 2.17 D (range - 1.75 to - 10.00 D) and the mean cylinder was -2.02 ± 1.09 D (range - 1.00 to - 5.00 D). The mean postoperative cylinder value was -0.60 ± 0.52 D at 12-month visit. The 12-month safety and efficacy indices were 0.98 ± 0.07 and 0.97 ± 0.12, respectively. The high astigmatism group showed significantly lower safety and efficacy indices. The postoperative residual astigmatism was 0.5 D or less in 73% of the eyes. Higher amount of residual astigmatism was observed in the high astigmatism group. The angle of error was ± 5 degrees in 49% and ± 15 degrees in 87% of the eyes. SMILE surgery is effective and safe method for correcting myopic astigmatism. Vector analysis indicated a tendency for the under correction of astigmatism in subjects with high astigmatism.