Magnitude Of Astigmatism Research Articles

Три предварительно заряженных и один ручной инжектор для имплантации ИОЛ: сравнительный анализ

Aim. To evaluate the incision width and implantation time of different IOL models using three preloaded and one manual injector. Material and methods. 146 patients (160 eyes) including 94 females and 52 males were included in a prospective study. Group I – Isert® (28 patients, 32 eyes); Group II – Multisert® (27 patients, 30 eyes); Group III – Autonome® (45 patients, 50 eyes) and Group IV – Monarch® (46 patients, 48 eyes). mean age of patients was 71.8 ± 11.7 years, follow-up period – 3 ± 0.2 months. Results. There were no significant differences (p > 0.05) between the groups when comparing the incision width before IOL implantation. After lens implantation, the incision width in group I was significantly higher than in groups II (p = 0.04), III (p = 0.037) and IV (p = 0.029). There were no significant differences in incision width after IOL implantation between groups II, III, and IV (p > 0.05). The average increase in corneal incision width in group I was 0.6 mm, and for groups II, III, and IV it ranged from 0.2 to 0.3 mm. Groups II, III, and IV showed lower values of surgically induced astigmatism compared with group I (0.47 ± 0.06, 0.41 ± 0.06, and 0.44 ± 0.07 D compared with 1.12 ± 0.17 D, respectively; p < 0.05 for all groups). No significant differences were found between groups II, III, and IV. Minimum implantation time was observed for groups II and III, maximum for groups I and IV, with a mean difference of about 30 seconds. Differences when comparing the mean IOL implantation time were not statistically significant (p > 0.05). Conclusion. This paper presents the first worldwide comparative analysis of four IOL implantation systems, including Isert®, Multisert®, Autonome®, and Monarch®. The new Multisert® IOL implantation system has similar advantages to the known monofocal IOL injectors with respect to corneal incision width, surgically induced astigmatism magnitude, and time required for IOL implantation. IOL implantation time did not depend on the type of implantation (hydro- or viscous) and the type of injector. Keywords: cataract, injector, Isert®, Multisert®, Autonome®, Monarch®, surgically induced astigmatism

Comparison of a New Scheimpflug Camera and Swept-Source Optical Coherence Tomographer for Measurements of Anterior Segment Parameters.

This study evaluated the differences and agreement between a new Scheimpflug camera (Scansys) and a swept-source anterior segment optical coherence tomographer (CASIA2) for measurements of the anterior segment of the eye in normal subjects. This prospective study included 84 eyes from 84 normal adult subjects who underwent three consecutive measurements with the Scansys and the CASIA2 in random order. The mean keratometry (Km), astigmatism magnitude (AST), J0, and J45 vectors for both anterior and posterior corneal surfaces, central corneal thickness (CCT), thinnest corneal thickness (TCT), and anterior chamber depth (ACD)were obtained by both devices. The difference between these two devices was assessed using paired ttest and violin plots. Bland-Altman plots and 95% limits of agreement (LoAs) were used to evaluate agreement. No statistically significant differences between the two devices were found for the anterior AST, anterior J45, and posterior J45 (P > 0.05). The remaining parameters were statistically significant (P ≤ 0.05), but the differences not clinically significant. The violin plots showed that the distribution and probability density of the measured parameters were similar for both devices. Bland-Altman plots revealed high agreement for the measured parameters between the Scansys and CASIA2, with narrow 95%LoAs. In terms of assessing parameters for the anterior segment, our study indicated that Scansys and CASIA2 generally showed significant agreement. The two devices used in this study's assessment of all the parameters can be used interchangeably in refractive analysis.

Poster Session: Peripheral blur may provide the eye with a cue for the sign of defocus.

The sign of defocus is used by the retina to guide emmetropization. However, the means by which the eye determines whether light is focused in front of, or behind the retina, remains elusive. In the current study, we propose a new cue for the sign of defocus: the orientation of the anisotropic peripheral blur. Previously published [1] population averages of wavefront aberrations across the horizontal visual field in hyperopes, emmetropes and myopes were used to assess peripheral optical quality and blur orientation. Due to the large magnitudes of off-axis astigmatism and coma, the peripheral retinal image quality was dominated by anisotropic blur, whose direction was also correlated with refractive error (vertically elongated peripheral blur in myopic eyes and horizontally elongated peripheral blur in emmetropic and hyperopic eyes). The differences in groups may be due to the interaction between peripheral wavefront aberrations and globe shape (i.e. peripheral axial length). We also found an interaction between longitudinal chromatic aberration and off-axis astigmatism, wherein peripheral blur orientation is wavelength dependent, raising additional questions pertaining to the nature of chromatic cues. The orientation of peripheral blur may provide the retina with an optical cue for the sign of defocus, potentially playing an important role in emmetropization. [1] Romashchenko et al., "Peripheral refraction and higher order aberrations." Clin Exp Optom 103.1 (2020): 86-94.

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.].

Outcomes of peripheral corneal relaxing incisions for residual astigmatism in patients after cataract surgery.

To evaluate the outcomes of peripheral corneal relaxing incisions (PCRIs) for correcting residual astigmatism in eyes after cataract surgery. Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. Retrospective case series. Retrospectively, we reviewed all consecutive cases that had previous cataract surgery and subsequent PCRIs by 1 surgeon. The PCRI length was determined according to a nomogram based on age and manifest refractive astigmatism. Visual acuity and manifest refractive astigmatism before and after the PCRIs were compared. Vector analysis was performed, and net refractive changes along the incision meridian were calculated. Criteria were met by 111 eyes. After the PCRIs, mean uncorrected visual acuity was significantly improved, and the percentage of eyes with uncorrected distance visual acuity of ≥20/20 increased significantly by 36%; the mean refractive astigmatism magnitude decreased significantly, and the percentages of eyes with refractive cylinder of ≤0.25 diopters (D) and ≤0.50 D increased significantly by 63% and 75%, respectively (all P < .05). The vector magnitude difference between pre- and post-operative refractive astigmatism was 0.88 ± 0.38 D. The postoperative refractive astigmatism had significantly smaller centroid and variance values than the preoperative refractive astigmatism ( P < .05). PCRIs are an effective approach for correcting low amounts of residual astigmatism in patients after cataract surgery.

Effects of atropine 0.01% on refractive errors in children with myopia

BackgroundLittle is known about changes in astigmatism during atropine treatment. We aimed to explore the effects of atropine 0.01% eye drops on both spherical and cylindrical refractive errors in myopic children. MethodsChildren aged 6–14 years with myopia ≥ −6.00 D and < −0.50 D, and total astigmatism > −2.00 D in at least one eye were enrolled. Subjects were randomised either to receive atropine 0.01% once nightly with single-vision lenses or simply to wear single-vision lenses and were followed up at 3-month intervals. Cycloplegic refraction and axial length were measured. The magnitude and direction of total astigmatism (TA), corneal astigmatism (CA), and residual astigmatism (RA) were evaluated. ResultsOverall, 119 eyes (69 eyes in the atropine group and 50 eyes in the control group) were included in the final analyses after 9 months. Atropine-treated eyes showed significantly less progression of myopia than did control eyes (spherical equivalent: −0.35 ± 0.33 vs. −0.56 ± 0.49 D, p = 0.001; axial length: 0.20 ± 0.19 vs. 0.33 ± 0.19 mm, p < 0.001). Compared with control eyes (−0.04 ± 0.23 D), a significant increase in TA was observed in the atropine-treated eyes (−0.14 ± 0.29 D); this was mainly attributed to the increase in CA (−0.17 ± 0.26 D) rather than the minor decrease in RA (0.02 ± 0.32 D). ConclusionsAtropine 0.01% was effective in preventing myopia progression, whereas 9 months of atropine treatment resulted in a clinically small, but statistically significant increase in TA in myopic Chinese children.

Comparing high and low energy outcomes on day one for SmartSight myopic-astigmatism treatments with the SCHWIND ATOS: a retrospective case series

BackgroundImpact of low energy asymmetric spacings vs. high energy symmetric spacings on the immediate/early (postoperative day 1 (POD1)) outcomes of SmartSight lenticule extraction for myopic astigmatism with a new femtosecond laser system.MethodsThe first 112 eyes of 56 patients consecutively treated using low energy asymmetric spacings (Group A; Study group) were compared at POD1 to the last 112 eyes of 56 patients consecutively treated using high energy symmetric spacings (Group S; Controls). Mean age of the patients was 28 ± 5 years with a mean spherical equivalent of -4.41 ± 1.76 diopters (D) and a mean magnitude of refractive astigmatism of 0.89 ± 0.82 D.ResultsLaser Energy was -25 ± 1nJ lower for asymmetric treatments (p < .0001); Spot and Track distances were + 0.7 ± 0.1 µm larger and -0.8 ± 0.1 µm tighter for asymmetric treatments, respectively (p < .0001 for both). At POD1, astigmatism was -0.08 ± 0.02D lower for asymmetric treatments (p < .0003); uncorrected and corrected visual acuities (UDVA and CDVA, respectively) were -0.03 ± 0.01logMAR better for asymmetric treatments (p < .0007); differences between postop UDVA and preop CDVA along with change in CDVA were + 0.3 ± 0.1lines better for asymmetric treatments (p < .0003).ConclusionsLenticule extraction treatment using SmartSight is safe and efficacious already at POD1. Findings suggest that low energy asymmetric spacings may further improve the immediate and short-term outcomes of SmartSight lenticule extraction in the treatment of myopic astigmatism compared to conventional settings (high energy symmetric spacings).

Prevalence of Corneal Astigmatism in Age Related Cataract Patient in a Tertiary Eye Hospital

Background: To investigate the magnitude and pattern of pre-existing corneal astigmatism in age related cataract patient.&#x0D; Method: This prospective observational study was carried out in a tertiary eye hospital from January 2020 to June 2020. We examined 577 eyes of 532 patients who underwent cataract surgery. The mean age at the time of surgery was 61.2 ±7.1 (40 to 100) years. Corneal astigmatism was measured with Auto Refracto Keratometer at least two times for each patient. Astigmatism was calculated from dioptric difference of vertical reading from horizontal reading. With the rule (WTR) astigmatism was considered when steep meridian at 900±200. Against the rule (ATR) astigmatism was considered when steep meridian at 1800±200. Astigmatism is in other direction is defined as oblique.&#x0D; Result: The pattern of astigmatism was ATR astigmatism in 237 eyes (41%), WTR astigmatism in 165 eyes (28.6%) and Oblique in 175 eyes (30.4%). Prevalence of ATR astigmatism was more than WTR astigmatism and prevalence of ATR astigmatism axis significantly increased with the increase in age. Average corneal power was 45.23D. Corneal astigmatism was 0.0D to 0.5D in 274 eyes (47.5%), 0.51D to 1.0D in 175 eyes (30.3%), 1.01D to 2.0D in 98 eyes (17.0%) and more than 2D in 30 eyes (5.2%) cases. Corneal astigmatism of most cataract surgery candidates fell between 0.50D to 1.50 D in 360 eyes (62.4%) cases.&#x0D; Conclusion: Thirty five percent (35%) pre-operative patient had 1D or more corneal astigmatism and sixty five percent (65%) had less than 1Dcorneal astigmatism.&#x0D; Central Medical College Journal Vol 6 No 2 Jauly 2022 Page: 67-70

Short-Term Impact of Different Corneal Incision Positions on Postoperative Astigmatism and Visual Quality After SMILE Surgery.

This study aimed to evaluate the short-term impact of different incision positions on astigmatism and visual quality after small incision lenticule extraction (SMILE) surgery. This prospective study enrolled patients who decided to have SMILE to correct myopia. Patients were randomly allocated into three groups of different incision positions (groupA, B, and C with incision position at 90°, 120°, and 150° respectively). Preoperative and postoperative visual acuity, spherical equivalent, and high-order aberrations (HOAs) were measured and compared among groups. Astigmatism was analyzed with the ASSORT Group Analysis Calculator based on the Alpins method. A total of 148 eyes were included for analysis (48 eyes in groupA, 50 eyes in groupB, and 50 eyes in groupC). At 1month postoperatively, the mean uncorrected distance visual acuity (UDVA) logMAR in groupA, B, and C was - 0.03, - 0.03, and - 0.04, respectively. The mean corrected distance visual acuity (CDVA) logMAR in groupA, B, and C was - 0.03, - 0.04, and - 0.04, respectively (P > 0.05). The mean postoperative spherical equivalent (SE) values were - 0.01 ± 0.38, - 0.07 ± 0.39, and - 0.16 ± 0.49 (D) in groupA, B, and C, respectively (P > 0.05). There was no statistically significant difference in preoperative and postoperative magnitude of astigmatism among different groups (P > 0.05). Significant differences were found in the distribution of astigmatism axis among the three groups at 1day (P = 0.02) and 1week (P = 0.02) postoperatively. However, such differences were no longer significant at 1month after surgery (P > 0.05). No significant differences were found in HOAs among different groups 1month after surgery (P > 0.05). Different incision positions have no effect on postoperative astigmatism and visual quality 1month after SMILE surgery, though differences were found in the distribution of the astigmatism axis within 1week after the surgery.

Clinical Outcomes of Toric Intraocular Lenses in Patients with Fuchs Endothelial Corneal Dystrophy.

Implantation of toric intraocular lenses (IOLs) in patients with Fuchs endothelial corneal dystrophy (FECD) is still considered relatively contraindicated, without sufficient clinical evidence. Therefore, this study was designed to evaluate the results of toric IOL implantation in patients with FECD. A retrospective case-control study of 28 eyes of FECD patients and 84 eyes of healthy control patients who received toric IOLs during routine cataract surgery was performed. The outcome measures were uncorrected and corrected distance visual acuity, spherical equivalent, and refractive residual astigmatism. The mean postoperative uncorrected and corrected distance visual acuity in the FECD eyes compared to the control eyes were 0.15 ± 0.14 vs. 0.13 ± 0.17, respectively (P = 0.32), and 0.05 ± 0.08 vs. 0.06 ± 0.10, respectively (P = 0.95). The spherical equivalent in the FECD eyes compared to the control eyes was -0.29 ± 0.43 vs. -0.21 ± 0.50, respectively (P = 0.19). The preoperative corneal centroid astigmatism in the FECD eyes compared to the control eyes was 0.85D@93° ± 2.42° vs. 0.23D@68° ± 2.50°, respectively (P = 0.43), and the mean preoperative corneal astigmatism magnitude was 2.26 ± 1.1D vs. 2.28 ± 1.03D, respectively (P = 0.82). A trend toward higher postoperative refractive centroid astigmatism was found in the FECD eyes compared with the control eyes: 0.24D@28° ± 0.57° vs. 0.03D@127° ± 0.53°, respectively (P = 0.09). However, the mean refractive astigmatism magnitude was similar in FECD eyes and the healthy control eyes: 0.52 ± 0.31D vs. 0.42 ± 0.31D, respectively (P = 0.44) (D diopters). The postoperative refractive astigmatism (both centroid astigmatism and mean magnitude astigmatism) was no higher than 0.52D in both groups. Therefore, FECD patients without corneal edema can be considered for toric IOLs.

The Effect of Surgical Treatment of Horizontal Strabismus on Refractive Changes in Adult Patients

Concomitant strabismus and refractive anomalies are often common pathological conditions in adult patients. The patient’s desire to get rid of both problems poses a question to the surgeon about the order of surgical interventions. With non-accommodative concomitant strabismus, the question is not so unambiguous. Despite a significant number of studies devoted to this topic, there is still no unequivocal opinion on the significance of refractive error after strabismus surgery. Thus, it remains an urgent task to study of possible surgically induced refractive changes after interventions on extraocular muscles and their assessment during the observation period.Purpose. Evaluation of the effect of surgical treatment of horizontal strabismus in adults on refractive and astigmatic status.Patients and methods. A prospective study of 30 patients with concomitant convergent or divergent strabismus. Each patient underwent surgery for horizontal strabismus, which consisted in recession and resection of the extraocular muscles of one eye. The spheroequivalent (SE) and cylinder (Cyl) values were determined before surgery, 1, 3, and 6 months after surgery. Refractive changes were calculated in the postoperative period, both for the spheroequivalent and for the cylinder, after 1 month (SIRC1), 3 months (SIRC2) and 6 months (SIRC3). In addition, the difference (d) between SIRC1 and SIRC3 was calculated to determine if they were temporary or permanent. Analysis of the induced changes in the magnitude and direction of astigmatism was performed using vector analysis.Results. The dynamics of SE values within 6 months after surgery shifted to insignificant myopia, however, no significant static difference in this parameter was found (p = 0.17). The mean change in spherical equivalent (SE) refraction was 0.22 ± 0.47 diopters in SIRC1, 0.15 ± 0.44 diopters in SIRC2, and 0.12 ± 0.51 diopters in SIRC3. There was no statistically significant difference between changes in surgically induced refraction at different times after surgery (p = 0.34). The difference (SIRC d) between SIRC1 and SIRC3 for the spheroequivalent was 0.096 ± 0.480 and can be interpreted as a decrease in surgically induced refraction error within 6 months after surgery. Surgically induced astigmatism at different times after surgery was: SIRC1 = 0.44 ± 0.39, SIRC2 = 0.47 ± 0.41, SIRC3 = 0.43 ± 0.29. There was no statistically significant difference in this parameter during the study period (p = 0.1). The difference (SIRC d) between SIRC1 and SIRC3 for astigmatism was 0.0001 ± 0.3200, which indicates stable values of astigmatism. According to the vector analysis, the magnitude and axis of preoperative astigmatism was 1.131 ± 0.410 ax172 and is close to the actual postoperative values of 1.17 ± 0.50 ax172. The vector of surgically induced astigmatism was 0.43 ± 0.10 ax84. These changes were not statistically or clinically significant.Conclusion. In general, the refractive and astigmatic status does not change after surgical treatment of horizontal strabismus. However, in this study, there was a myopic refraction shift during the first 3–6 months after surgery. In this connection, it is possible to recommend refractive operations to adult patients 3–6 months after strabismus surgery.

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

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

Accuracy of the LaserArcs Femtosecond Cataract Surgery Arcuate Incision Nomogram in Patients Undergoing Cataract Surgery and Astigmatism Reduction.

The purpose of this study is to evaluate the efficacy and safety of the laserarcs.com nomogram in reducing astigmatism among cataract patients that underwent astigmatism reduction with laser arcuate incisions. In this retrospective study, 50 patients who underwent uncomplicated cataract surgery with laser arc incisions for the reduction of astigmatism with a single surgeon between the dates of January 23, 2021 and February 10, 2022 were evaluated in a single eye. Preoperative astigmatism was determined on the basis of keratometry from biometry (IOLmaster, Carl Zeiss Meditec or LenStar LS900, Haag-Streit, Bern, Switzerland) and was compared to the postoperative manifest astigmatism. The percent change in the absolute magnitude of astigmatism was calculated along with the percent of patients with various levels of postoperative astigmatism. Mean cylinder was 0.97 ± 0.49 D pre-op and 0.21 ± 0.28 D postop. Mean reduction in cylinder was 81.4 ± 47.7% (P < 0.00001, one-sample t-test compared to a hypothetical 60% reduction in cylinder). Residual cylinder was ≤0.5 D in 90%, 0.25 D in 72%, and 0 D in 58%. Postoperative uncorrected visual acuity was 20/30 or better in 92% and 20/20 or better in 40%. Subgroup analysis showed that residual astigmatism was not affected by patient age, magnitude of preoperative astigmatism, preoperative spherical equivalent, or corneal curvature. No adverse events related to the laser arcuate incisions were noted. Use of the LaserArcs nomogram yielded a significant reduction in preoperative astigmatism. Postoperative uncorrected visual acuity was substantially similar to best-corrected visual acuity, suggesting that many patients undergoing treatment will function without correction for distance tasks.

Ptosis effects on intraocular lens power calculation.

To evaluate quantitatively ocular biometric parameters and intraocular lens (IOL) power measurements post-ptosis surgery. This study comprised involutional ptosis patients divided into droopy eyelid severity groups: Group 1:>4 mm, Group 2:3-4 mm, and Group 3:1-2 mm. The patients underwent anterior levator resection (ALR), and preoperative and postoperative biometry measurements 3 months postoperatively were obtained. The Group 1 sample size was 19, Group 2 was 22, and Group 3 was 16. The mean K1, K2, and Km values significantly decreased 3 months postoperatively in Group 1 (P<0.001 for all). The mean K1, K2, and Km values non-significantly decreased 3 months postoperatively in Groups 2 and 3 (P>0.05 for all). The mean corneal astigmatism magnitude decreased 3 months postoperatively in Group 1 (P<0.01), Group 2 (P=0.186), and Group 3 (P=0.952). The mean recommended IOL powers targeting emmetropia increased postoperatively in Group 1 and were similar pre- and postoperatively in Groups 2 and 3. In Group 1, the mean changes after ptosis surgery by formula were 0.47 D for SRK/T, 0.52 D for Hoffer Q, 0.55 D for Haigis, 0.50 D for Barrett Universal II and 0.55 D for Holladay 2. Ptosis > 4 mm significantly impacts corneal curvature values and IOL power calculations when cataract surgery is planned. Surgeons might consider altering their lens power choice accordingly if cataract surgery is to be sequentially followed by ptosis repair.

Comparison of keratometry using SS-OCT and dual Scheimpflug-Placido imaging in postmyopic corneal refractive surgery eyes.

To compare simulated (SimK) and total (True-K) keratometry and corneal astigmatism values between the IOLMaster 700 (IOLM) and Galilei G4 (G4) devices in postmyopic laser refractive surgery eyes. Methodist Eye Associates, Blanton Eye Institute, Houston Methodist Hospital, Houston, Texas. Retrospective cohort study. A chart review was conducted on patients with prior myopic laser-assisted in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK), undergoing phacoemulsification at a single institution from May 2019 through January 2022, who underwent imaging with both the IOLM and G4. Exclusion criteria were prior radial keratotomy, keratoectatic diseases, and inability to obtain a reliable image. Mean, flat, and steep SimK and True-K (TK from the IOLM and TCP IOL from the G4) values and astigmatism magnitude were compared. 50 eyes of 50 patients were included. The mean difference in SimK and True-K between devices (IOLM - G4) was -0.04 (95% CI -0.13 to 0.06; P > .05) diopters (D) and 1.14 (95% CI 1.02 to 1.25; P < .05) D, respectively. The IOLM measured steeper True-K values than the G4. There were no statistically significant differences between devices for all other SimK values, whereas for True-K there were significant differences in flat K and steep K ( P < .05), but not astigmatism magnitude. Despite an overall good correlation in postmyopic laser refractive surgery eyes in keratometry and astigmatism measurements, there is a significant difference in True-K, with the IOLM measuring steeper values by about 1.0 D compared with the G4, similar to prior studies on nonrefractive surgery eyes.

Astigmatism Profile in a Large Series of Brazilian Patients.

To assess anterior, posterior, and total corneal astigmatism in a large sample of Brazilian patients. In this retrospective cross-sectional study, all patients whose corneas were imaged with the Galilei G6 (Ziemer Ophthalmology) between January 2017 and February 2019 at HOPE Eye Hospital, in Recife, Brazil, were eligible to participate. Anterior, posterior, and total corneal astigmatism values were collected and analyzed. The study included 3,253 eyes of 1,919 patients. The mean magnitude of the anterior, posterior, and total corneal astigmatism was 1.50 ± 1.11, 0.34 ± 0.15, and 1.29 ± 0.98 diopters (D), respectively. Corneal astigmatism was greater than 0.50 D in the anterior cornea of 86.3% of eyes (2,807 eyes) and in the posterior cornea of 13.2% of eyes (429 eyes). Vertical alignment of the steepest corneal meridian was observed in the anterior cornea of 74.5% of eyes (2,423 eyes) and in the posterior cornea of 93.1% of eyes (3,029 eyes). The correlation between the astigmatism magnitude of the anterior and posterior cornea was strong when the steep anterior meridian was aligned vertically (r = 0.720; P < .001), and absent when it was aligned horizontally (r = 0.102; P = .036). Corneal astigmatism values in the Brazilian population were similar to those found in other ethnicities, suggesting that toric calculators, nomograms, coefficients of adjustment, and formulas that were developed based on astigmatism values of other populations may be used in Brazilian patients with comparable accuracy. [J Refract Surg. 2023;39(1):56-60.].

Changes in Vector Astigmatism After Superotemporal Versus Temporal Clear Corneal Incision Cataract Surgery.

To investigate vector and refractive astigmatism changes after superotemporal versus temporal clear corneal incision cataract surgery. Patients were diagnosed with age-related cataract with corneal astigmatism < 1.5 diopters (D) and were divided into two groups: superotemporal incision (R group) and temporal incision (L group). Uncorrected visual acuity, manifest refraction, corneal topography, anterior segment optical coherence tomography was performed pre- and six months postoperatively. Total ocular astigmatism, corneal astigmatism, vector of surgically induced corneal astigmatism (SICA), non-corneal ocular residual astigmatism (N-CORA), postoperative intraocular lens decentration and tilt were analyzed. Results: Thirty-eight subjects were included: 21, R group; 17, L group. After surgery, the N-CORA decreased significantly from 1.17±0.72 D to 0.73±0.47 D in all patients (P=0.001), 1.03±0.52 D to 0.70±0.40 D in the R group (P=0.005) and 1.35±0.90 D to 0.78±0.55 D in the L group (P=0.033). Significant differences between t:he R and L groups were found in the postoperative meridian of anterior corneal astigmatism (75.95±52.50 vs 116.79±47.29; P=0.017), total corneal astigmatism (51.65±42.75 vs 95.20±57.32; P=0.011), J45 change vector of SICA in the anterior cornea (-0.10±0.18 vs 0.00±0.11; P=0.048) and total cornea surface (-0.14±0.17 vs 0.03±0.12; P=0.001). Conclusion: The N-CORA decreased significantly after cataract surgery. Superotemporal and temporal incisions caused differences in the meridian components of oblique astigmatism in some patients but did not have a significant effect on the magnitude of corneal astigmatism.

Roles of Toric intraocular Lens implantation on visual acuity and astigmatism in glaucomatous eyes treated with iStent and cataract surgery

BackgroundTo assess the efficacy of toric intraocular lenses (IOLs) in combined cataract and minimally invasive glaucoma surgery (MIGS), visual and refractive outcomes were compared between eyes implanted with non-toric and toric IOLs during iStent triple procedures.MethodsIn this retrospective study, open angle glaucoma eyes with preexisting corneal astigmatism of -1.5 diopter (D) or more and implanted with non-toric (n = 9) or toric (n = 9) IOLs were included. The main outcome measures were the intergroup difference in the uncorrected visual acuity (UCVA) and refractive astigmatism at 3 months postoperatively.ResultsPreoperatively, the logarithm of the minimum angle of resolution (logMAR) UCVAs and refractive astigmatism were equivalent between the groups. Postoperatively, the logMAR UCVA (non-toric, 0.45 ± 0.31; toric, 0.14 ± 0.15; P = 0.021) was significantly better and the refractive astigmatism (non-toric, -2.03 ± 0.63 D; toric, -0.67 ± 0.53 D; P = 0.0014) significantly less in the toric group. The toric group had postoperative improvements in the logMAR UCVA (-0.21, P = 0.020) and refractive astigmatism (+ 1.72 D, P = 0.0039). Vector analyses showed the postoperative centroid magnitude and confidence eclipses of refractive astigmatism was less in the toric group (0.47 D at 173°±0.73D) than the non-toric group (1.10 D at 2°±1.91D). Postoperatively, 78% of eyes in the toric group had 1.0 D or less refractive astigmatism compared with 11% in the non-toric group. Surgically induced astigmatism (non-toric, 0.18 D at 65°; toric, 0.29 D at 137°) did not differ between groups.ConclusionUse of toric IOLs is a reasonable option for better visual outcomes when the combined cataract and iStent surgery is performed in glaucomatous eyes with corneal astigmatism.

Effect of incision location on with-the-rule astigmatism correction after SMILE.

To explore the influence of two different incision positions of small incision lenticule extraction (SMILE) on astigmatism correction. A total of 86 eyes of 86 patients who underwent SMILE surgery were included in this retrospective study. The criteria included that the preoperative astigmatism axis to be within 165° to 180° or 5° to 15°. All eyes were divided into two groups according to the incision position. The incisions of 34 eyes were either located on the superior temporal side of the right eye or superior nasal side of the left eye (120° group), and 52 eyes were located on the superior side (90° group). Vector analysis was used to analyze pre- and postoperative 3-month astigmatism, while subgroup analysis was applied according to the preoperative astigmatism. No significant difference of preoperative parameters was found between the two groups (P > 0.05). The efficacy and safety indexes were 1.11 ± 0.16 and 1.15 ± 0.16 in the 120° group, the numbers were 1.15 ± 0.17 and 1.16 ± 0.14 in the 90° group (P = 0.629 and P = 0.871). There was no significant difference in target-induced astigmatism (TIA), TIA axis, surgically induced astigmatism (SIA) magnitude, SIA axis, distance vision (DV) magnitude, DV axis, correction index (CI), angle of error (AofE), |AofE|, magnitude of error (MofE), index of success (IOS), or flattening index (FI) between 120° group and 90° group (P > 0.05). No significant difference was found in the subgroup analysis (P > 0.05). The incision position has limited astigmatic effect, and the operation-induced astigmatism of SMILE surgery after 3 months was little.

Posterior Corneal Astigmatism Does Not Influence Manifest-Treated Topography-guided LASIK Outcomes

To investigate whether the magnitude of posterior corneal astigmatism (PCA) impacts refractive and visual outcomes of primary topography-guided laser in situ keratomileusis (LASIK) and to provide guidance on treating eyes with high PCA. Comparative retrospective analysis of 4,541 consecutive eyes treated with Contoura (Alcon Laboratories, Inc) on the manifest refractive astigmatism. Standard outcomes of the 1,514 eyes with the lowest PCA (first tercile; low PCA group) were compared to the 1,514 eyes with the highest PCA (last tercile; high PCA group). Pearson correlation coefficient was used to assess relationships between variables. Preoperatively, 20.9% of eyes presented with PCA of 0.50 diopters (D) or greater. The mean PCA was 0.18 ± 0.07 D in eyes with low PCA, and 0.50 ± 0.11 D in eyes with high PCA. An equivalent number of eyes achieved a cumulative postoperative unilateral uncorrected distance visual acuity of 20/20 in both the low PCA and high PCA groups (95.3% vs 94.7%; P = .4489). The efficacy index of both low and high PCA eyes was identical (0.99 ± 0.06 vs 0.99 ± 0.08; P = .3192), as was the safety index (1.00 ± 0.02 vs 1.00 ± 0.03; P = .0110). The magnitude of preoperative PCA was weakly correlated with postoperative refractive astigmatism (R = 0.1323), but not with postoperative defocus equivalent (R = -0.0414) or spherical equivalent (R = -0.0128). PCA does not negatively impact the outcomes of topography-guided LASIK targeting the manifest refraction, having identical accuracy, efficacy, and safety in eyes with both low and high PCA. There is no scientific basis to measure and consider PCA in topography-guided LASIK planning software or nomograms if the excimer laser treatment input targets the manifest refraction. [J Refract Surg. 2022;38(12):780-790.].