Target-induced Astigmatism Research Articles

Modified femtosecond laser-assisted arcuate keratotomy for managing low corneal astigmatism using trifocal intraocular lens implantation in Chinese cataract patients.

To evaluate the visual outcome and astigmatic correction following trifocal intraocular lens (IOL) implantation using the modified femtosecond laser-assisted arcuate keratotomy (FSAK) in Chinese cataract patients with low astigmatism. This retrospective study included consecutive cataract patients with regular corneal astigmatism ranging from 0.75 to 1.5 D who underwent FSAK combined with the trifocal IOL implantation between November 2020 and September 2022. Monocular uncorrected distance visual acuity, uncorrected intermediate visual acuity, uncorrected near visual acuity, and refractive data were collected at the 3-month follow-up. The pre- and post-operative high-order aberrations (HOAs) were recorded. The variation in astigmatism was analyzed using Alpins vector analysis. A total of 27 eyes from 23 patients were analyzed. The monocular uncorrected distance visual acuity (UDVA) (5 m) at the 3-month follow-up was 0.04 ± 0.09 logarithm of the minimum angle of resolution (logMAR), which was significantly improved compared with the preoperative value of 0.95 ± 0.51 logMAR (P <.001). The corneal astigmatism was significantly reduced from 1.24 ± 0.42 D to 0.49 ± 0.34 D (P <.001). The target-induced astigmatism (TIA) was 1.25 ± 0.43 D, the surgically induced astigmatism (SIA) was 1.16 ± 0.52 D, and the difference vector (DV) was 0.5 ± 0.34 D. The magnitude of error (ME) (difference between SIA and TIA) was -0.1 ± 0.41 D, and the correction index (CI) (ratio of SIA to TIA) was 0.93 ± 0.36. The angle of error was 3.92° ± 16.90°. Total HOA was reduced from 0.89 ± 1.11 to 0.41 ± 0.55 (P = 0.184), and the corneal HOA was lowered from 0.17 ± 0.18 to 0.10 ± 0.10 (P = 0.129). Implantation of trifocal IOL following the modified FSAK in Chinese cataract patients exhibited excellent visual efficacy and effectively reduced corneal astigmatism.

Refractive Astigmatism Outcomes of Femtosecond Laser-Assisted Arcuate Keratotomies Combined with Femtosecond Laser-Assisted Cataract Surgery: Two-Year Results

Purpose To evaluate the effectiveness and stability of refractive astigmatism reduction after penetrating femtosecond laser-assisted arcuate keratotomy performed at the time of femtosecond laser-assisted cataract surgery. Methods Non-randomized retrospective data analysis of all patients that underwent femtosecond laser-assisted cataract surgery with femtosecond laser-assisted arcuate keratotomy over a 4-year period with a non-toric monofocal intraocular lens (2017–2021) at a tertiary care academic center. Postoperative visual acuity, manifest refraction, and predicted residual refractive error were also recorded at 1 month, 3–6 months, 12–18 months, and 2 years postoperatively. Preoperative keratometric astigmatism was compared to postoperative refractive astigmatism using vector calculations and the ASCRS double-angle plot tool. Results This study comprised 266 eyes (179 patients) that met inclusion criteria. The mean preoperative keratometric astigmatism magnitude was 0.99 ± 0.53 D. At 1 month, 3–6 months, 12–18 months, and 2 years postoperatively, the mean refractive cylinder was 0.49 ± 0.45 D, 0.49 ± 0.45 D, 0.55 ± 0.54 D, and 0.52 ± 0.46 D, respectively. Horizontal against-the-rule astigmatism showed a higher tendency toward undercorrection than vertical with-the-rule astigmatism, which had a slightly higher tendency toward overcorrection. With-the-rule astigmatism had smaller difference vectors between target-induced astigmatism and surgically induced astigmatism. Conclusions Femtosecond laser-assisted arcuate keratotomy performed at the time of femtosecond laser-assisted cataract surgery was an effective option for correcting low-to-moderate corneal astigmatism for up to 2 years.

Effect of Cyclotorsion Compensation in Small Incision Lenticule Extraction Surgery for the Correction of Myopic Astigmatism: A Systematic Review and Meta-Analysis.

Small incision lenticule extraction (SMILE) has made notable advancements in addressing myopic astigmatism. Nevertheless, the potential impact of cyclotorsion on surgical outcomes cannot be overlooked. This study aims to assess the effectiveness of cyclotorsion compensation technology in SMILE surgery for the correction of myopic astigmatism, examining its influence on postoperative visual quality. A systematic review and meta-analysis were conducted. A comprehensive literature search was performed using databases, including PubMed, Web of Science, EMBASE, Cochrane Library, EBSCO, Scopus, CNKI, VIP, and Wan Fang. Studies meeting the criteria were selected and included. Data were independently extracted by three authors. Clinical outcome parameters were analyzed using Review Manager version 5.3. This meta-analysis included ten studies. The results showed that, compared with the control group (cyclotorsion compensation was not performed in SMILE), the following indicators in the cyclotorsion compensation group were: residual astigmatism (RA) [weighted mean difference (MD) = 0.73, 95% confidence interval (CI) + 0.26 to + 1.19, P = 0.002], spherical equivalent (SE) (MD = 1.99, 95% CI + 0.77 to + 3.21, P = 0.001), coma (MD = -0.06, 95% CI -0.08 to -0.04, P < 0.00001), higher-order aberrations (HOAs) (MD = -0.04, 95% CI -0.06 to -0.02, P < 0.0001), follow-up 6-month angle of error (AE) (MD = -2.67, 95% CI -3.71 to -1.63, P < 0.00001), and follow-up 6-month uncorrected distance visual acuity (UDVA) (MD = -0.05, 95% CI -0.08 to -0.01, P = 0.005), and the differences in results were statistically significant. However, the differences among correction index, index of success (IOS), targeted induced astigmatism (TIA), magnitude of error (ME), and spherical aberration (SA) were not statistically significant. Cyclotorsion compensation proves to be effective and predictable for correcting myopic astigmatism. The cyclotorsion compensation group demonstrated advantages over the control group in terms of postoperative residual astigmatism, and it induced fewer coma aberrations. Whether cyclotorsion compensation can lead to better visual quality remains to be seen, and further research on correcting myopic astigmatism through cyclotorsion compensation is warranted.

Using Total Corneal Astigmatism With Femtosecond Laser Cataract Surgery and Arcuate Keratotomy(ies) to Treat Low Amounts of Astigmatism.

The aim of this study was to evaluate outcomes using total corneal astigmatism (TCA) to calculate arcuate keratotomy(ies) (AK) parameters performed with femtosecond laser-assisted cataract surgery to reduce low corneal astigmatism. Patients who had femtosecond laser-assisted cataract surgery and AK with 0.50 diopter (D) to 1.30 D of TCA were included. Exclusion criteria were intraoperative complications, preexisting corneal surgery, and comorbidities that might adversely affect outcomes. Corneal tomography (Galilei G4, Zeimer Ophthalmic Systems AG) was performed preoperatively and 1 month postoperatively. TCA was input into the Donnenfeld limbal relaxing incisions nomogram to calculate the AK parameters. Preoperative and postoperative tomographic and subjective refractive measurements were compared. The Alpins method for vector analysis evaluated results. Eighty-two eyes of 82 patients were included. Mean preoperative TCA was significantly reduced from 0.80 ± 0.19 D to 0.51 D ± 0.26 D ( P < 0.001). Preoperative posterior corneal astigmatism, -0.28 ± 0.13 D, was unchanged, postoperative posterior corneal astigmatism, -0.28 ± 0.14 D ( P = 0.653). Target-induced astigmatism arithmetic mean (0.82 ± 0.21 D) was greater than that of the surgically induced astigmatism (0.70 ± 0.40 D), resulting in an arithmetic mean difference vector of 0.51 ± 0.27 D with a summated mean at 0.16 D at 20 degrees. The correction index was 0.87, indicating undercorrection. Angle of error arithmetic mean, -1.27 ± 23.27 degrees, indicated good alignment. Inputting TCA for calculation of femtosecond laser AK parameters can reduce low amounts of preoperative corneal astigmatism, thereby improving uncorrected vision.

Symmetrical femtosecond laser arc incision in correcting corneal astigmatism in cataract patients.

To evaluate the effect of symmetrical arc incision correcting corneal astigmatism in femtosecond laser-assisted phacoemulsification (FLACS). This study enrolled patients with cataract combined with regular corneal astigmatism of >0.75 D, who underwent FLACS. Symmetrical arc incision was set at 8 mm diameter and 85% depth. The follow-up time was 3-24mo (4.92±3.49mo). Pentacam recorded the corneal astigmatism and higher-order aberration at pre-operation and post-operation. The changes in corneal astigmatism were analyzed by Alpins method. The correlation of astigmatism type, age, corneal horizontal diameter, corneal thickness, arc incision length, and correction index (CI) was analyzed, and the residual corneal astigmatism was compared with the residual whole eye astigmatism. Totally 79 patients (102 eyes) were enrolled, 10 patients had corneal epithelial injury, 1 patient occurred corneal epithelial hyperplasia. The corneal astigmatism was 1.23±0.38 D pre-operation, and decreased to 0.76±0.39 D post-operation (t=10.146, P=0.000). Corneal high-order aberration was 0.17±0.08 µm pre-operation and 0.24±0.11 µm post-operation (t=-5.186, P=0.000). The residual corneal astigmatism and residual whole eye astigmatism were no significant difference (t=-0.347, P=0.729). Using Alpin's method, the following were determined: target-induced astigmatism (TIA) =1.23±0.38 D, surgery-induced astigmatism (SIA) =0.77±0.45 D, difference vector (DV)=0.77±0.39 D, and CI=0.54±0.28. Age, astigmatism size, corneal horizontal diameter, corneal thickness, and arc incision length were not correlated with CI. The CI for against the rule astigmatism (ATR) was better than that for with the rule astigmatism (WTR; P=0.001). Femtosecond laser-assisted astigmatic keratotomy has better CI of ATR, but increase higher-order corneal aberration. CI is not ideal, it's not a perfect choice if we pursue ideal correction effect.

Optimizing Refractive Outcomes of SMILE: Artificial Intelligence versus Conventional State-of-the-Art Nomograms

Purpose AI (artificial intelligence)-based methodologies have become established tools for researchers and physicians in the entire field of ophthalmology. However, the potential of AI to optimize the refractive outcome of keratorefractive surgery by means of machine learning (ML)-based nomograms has not been exhausted yet. In this study, we wanted to comprehensively compare state-of-the-art conventional nomograms for Small-Incision-Lenticule-Extraction (SMILE) with a novel ML-based nomogram regarding both their spherical and astigmatic predictability. Methods A total of 1,342 eyes were analyzed for creation of three different nomograms based on a linear model (LM), a generalized additive mixed model (GAMM) and an artificial-neuronal-network (ANN), respectively. A total of 16 patient- and treatment-related features were included. Each model was trained by 895 eyes and validated by the remaining 447 eyes. Predictability was assessed by the difference between attempted and achieved change in spherical equivalent (SE) and the difference between target induced astigmatism (TIA) and surgically induced astigmatism (SIA). The root mean squared error (RMSE) of each model was computed as a measure of overall model performance. Results The RMSE of LM, GAMM and ANN were 0.355, 0.348 and 0.367 for the prediction of SE and 0.279, 0.278 and 0.290 for the astigmatic correction, respectively. By applying the created models, the theoretical yield of eyes within ±0.50 D of SE from target refraction improved from 82 to 83% (LM), 84% (GAMM) and 83% (ANN), respectively. Astigmatic outcomes showed an improvement of eyes within ±0.50 D from TIA from 90 to 93% (LM), 93% (GAMM) and 92% (ANN), respectively. Subjective manifest refraction was the single most influential covariate in all models. Conclusion Machine learning endorsed the validity of state-of-the-art linear and non-linear SMILE nomograms. However, improving the accuracy of subjective manifest refraction seems warranted for optimizing ±0.50 D SE predictability beyond an apparent methodological 90% limit.

MEYEstro software: an automatic tool for standardized refractive surgery outcomes reporting

BackgroundStandardization for reporting medical outcomes enables clinical study comparisons and has a fundamental role in research reproducibility. In this context, we present mEYEstro, a free novel standalone application for automated standardized refractive surgery graphs. mEYEstro can be used for single and multiple group comparisons in corneal and intraocular refractive surgery patients. In less than 30 s and with minimal user manipulation, mEYEstro automatically creates the required journal standard graphs while simultaneously performing valid statistical analyses.ResultsThe software produces the following 11 standard graphs; Efficacy: 1. Cumulative uncorrected (UDVA) and corrected visual acuity (CDVA), 2. Difference between UDVA and CDVA, Safety: 3. Change in line of CDVA, Accuracy: 4. Spherical equivalent (SEQ) to intended target, 5. Attempted vs. achieved SEQ, 6. Defocus equivalent (DEQ) accuracy, 7. Refractive astigmatism accuracy, 8. Target-induced astigmatism vs. Surgically-induced astigmatism, 9. Correction index histogram, 10. Angle of error histogram, Stability: 11. SEQ stability over time. Percent proportions, means, standard deviations, Cohen's d effect sizes, and p-values are calculated and displayed on each graph. All graphs can be easily exported as high-resolution TIFF images for figures to use in scientific manuscripts and presentations.ConclusionsmEYEstro software enables clinicians, surgeons, and researchers, to easily and efficiently analyze refractive surgery outcomes using the standardized methodology required by several peer-reviewed ophthalmology journals.

Outcomes of Single-Step Transepithelial Photorefractive Keratectomy Compared With Alcohol-Assisted Photorefractive Keratectomy Using Wave-Light EX500 Platform.

Purpose To compare the visual outcome of transepithelial photorefractive keratectomy (PRK) against alcohol-assisted PRK in treating low-to-moderate myopia with or without astigmatism. Setting Dhahran Eye Specialist Hospital, Dhahran, Saudi Arabia. Design This is a retrospective study. Methods Forty eyes of 22 patients with myopia from -0.75 to -6.00 diopters (D) with or without astigmatism from 0 to -3D were included in this study. Preoperative and postoperative data of 20 eyes from 11 patients who underwent transepithelial PRK were compared with 20 eyes from 11 patients who underwent alcohol-assisted PRK were collected and analyzed. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest spherical equivalence (SE), manifest cylinder, vector analysis of astigmatism, and efficacy and safety indices were compared between the groups at a mean follow-up of one year postoperatively. Results Baseline characteristics were similar between groups, except the transepithelial PRK group had lower cylinder values than the alcohol-assisted PRK group by 0.69D. Regression analysis was used to control for the difference in the cylinder in all outcome parameters. Both groups had similar mean UDVA (p=0.73), CDVA (p=0.98), the proportion of eyes in either group achieved (20/20, 20/25, and 20/30) UDVA (p=0.72, 0.68 and 0.31 respectively) and percentage of eyes lost two lines of CDVA (p=1.0). There was no statistically significant difference between the two groups in regard to both efficacy and safety indices (p=0.55 and 0.67, respectively). Both groups had similar residual SE (p=0.72), the proportion of eyes within ±0.5D of SE (p=0.29), and residual refractive astigmatism (p=0.87). Both groups had similar difference vectors, surgically induced astigmatism, and correction index (p=0.82, 0.10, and 0.26, respectively). However, the transepithelial PRK group had lower target-induced astigmatism (TIA; p=0.01), higher magnitude of error (ME; p=0.05), and higher angle of error (AE; p=0.02) than the alcohol-assisted PRK group. Conclusion Transepithelial PRK had similar visual and refractive outcomes as alcohol-assisted PRK. This approach was considered as safe and effective as alcohol-assisted PRK in treating patients with low-to-moderate myopia with or without astigmatism.

Impact of crossplay between ocular aberrations and depth of focus in topo-guided laser-assisted in situ keratomileusis outcomes.

To develop a nomogram in cases with mismatch between subjective and Topolyzer cylinder, and based on the magnitude of the mismatch, customize a treatment plan to attain good visual outcomes post-laser-assisted in situ keratomileusis (LASIK) surgery. The patients were evaluated preoperatively using corneal tomography with Pentacam. Five optimal corneal topography scans were obtained from the Topolyzer Vario were used for planning the LASIK treatment. For the nomogram purpose, the patients were divided into three categories based on the difference between the subjective cylinder and Topolyzer (corneal) cylinder. The first group (group 1) consisted of eyes of patients, where the difference was less than or equal to 0.4 D. The second group (group 2) consisted of eyes, where the difference was more than 0.4 D and the subjective cylinder was lesser than the Topolyzer cylinder. The third group (group 3) included eyes where the difference was more than 0.4 D but the subjective cylinder was greater than the Topolyzer cylinder. LASIK was performed with the WaveLight FS 200 femtosecond laser and WaveLight EX500 excimer laser. Assessment of astigmatism correction for the three groups was done using Aplins vector analysis. For comparison of proportions, Chi-square test was used. A P value less than 0.05 was considered statistically significant. The UDVA was statistically significantly different when compared between groups 1 and 2 (P = 0.02). However, the corrected distance visual acuity (CDVA) was similar among all the three groups (P = 0.1). Group 3 showed an increase of residual cylinder by -0.25 D, which was significant at intermediate and near reading distances (P < 0.05). Group 3 showed significantly higher target-induced astigmatism (TIA) compared to groups 1 and 2 (P = 0.01). The mean surgically induced astigmatism (SIA) was the least in group 2, which was statistically significant (P < 0.01). The outcomes for distance vision using our nomogram postoperatively were excellent, but further refinement for improving the near vision outcomes is required.

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.

Femtosecond laser-assisted arcuate keratotomy for the management of corneal astigmatism in patients undergoing cataract surgery: Comparison with conventional cataract surgery.

PurposeTo assess the effects of femtosecond laser arcuate keratotomy with femtosecond laser-assisted cataract surgery in the management of corneal astigmatism, compared with conventional phacoemulsification cataract surgery.DesignRetrospective comparative interventional case series.MethodsA total of 2,498 eyes of consecutive patients who presented with 3.00 diopters (D) or under of astigmatism were included. The patients were treated with conventional phacoemulsification cataract surgery (conventional group) and femtosecond laser arcuate keratotomy with femtosecond laser-assisted cataract surgery (femtosecond group).ResultsSurgically induced astigmatism (SIA) was higher in the femtosecond group than the conventional group (0.215, p < 0.001). Difference vector (DV) was lower in the femtosecond group (-0.136, p < 0.001). The cut-off value of the overcorrection in the femtosecond group was 0.752 D of target induced astigmatism (TIA). For patients with TIA 0.75 D or under, DV and the value of index of success (TIA into DV) were significantly higher in the femtosecond group (p = 0.022 and < 0.001). The overcorrection ratios were 48.8% in the conventional and 58.9% in the femtosecond group. (p < 0.001). For patients with TIA over 0.75 D, SIA and correction index (TIA into SIA) was higher in femtosecond group (0.310 and 0.250, p < 0.001 and < 0.001, respectively). Absolute angle of error was 20.612 ± 18.497 in the femtosecond group and higher than the conventional group (2.778, p = 0.010).ConclusionFemtosecond laser arcuate keratotomy in cataract surgery was effective in SIA between 0.75 to 3.00 D of corneal astigmatism. However, the overcorrection in the lower astigmatism and angle of error in the higher astigmatism were due to the postoperative corneal astigmatism not decreasing as much as SIA. Overcoming these challenges will lead to better management of corneal astigmatism.

SMILE after DALK to reduce residual refraction: two-year results.

To determine the two-year results of small incision lenticule extraction (SMILE) for correcting post-keratoplasty myopia and myopic astigmatism. In this case-series study, 10 eyes of 10 patients with a 6- to 10-year history of successful deep lamellar keratoplasty (DALK) underwent SMILE using the VisuMax laser platform. Ophthalmologic examinations and visual acuity and refraction measurement were taken pre- and 1, 3, 6, 12, and 24months postoperatively. The Pentacam and Sirius imaging were done in the first and last follow-up sessions. The mean age of the patients was 39.60 ± 7.86years. Six subjects were male. Two years after SMILE, the mean improvement in UDVA and CDVA was 3.60 ± 1.84 (P < 0.001) and 1.60 ± 2.91 (P = 0.231) LogMAR, respectively. The mean decrease in spherical equivalent, spherical error, and cylinder power was 1.92 ± 1.96 diopter (D) (P = 0.013), 0.70 ± 3.05D (P = 0.213), and 2.42 ± 2.91D (P = 0.024), respectively. The vector mean target-induced astigmatism, surgical-induced astigmatism, and difference vector were 1.30D@44˚, 1.11D@24˚, and 0.86D@73˚, respectively. Two years after SMILE, vertical coma, horizontal coma, and spherical aberration increased by 0.44 ± 0.51, 0.23 ± 0.32, and 0.02 ± 0.16µm, respectively, (all P > 0.05) while trefoil reduced by 0.29 ± 0.75µm (P = 0.428). SMILE can be an effective procedure for reducing refraction and astigmatism after DALK in patients with moderate myopia and moderate to severe astigmatism and improves the visual acuity in these patients. Axis rotation during surgery may result in under-correction of astigmatism. Refinement of SMILE treatment nomogram for post-DALK cases seems necessary.

Vector analysis of high astigmatism (\u2265\u20092.0 diopters) correction after small-incision lenticule extraction with stringent head positioning and femtosecond laser-assisted laser in situ keratomileusis with compensation of cyclotorsion

BackgroundThe purpose of this study was to compare the astigmatic correction by vector analysis in patients with high myopic astigmatism after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) with cyclotorsion compensation or small-incision lenticule extraction (SMILE) with stringent head positioning.SettingBeijing Aier-Intech Eye Hospital, Beijing, China.DesignA retrospective case series.MethodsPatients who had correction of myopic astigmatism of 2 diopters (D) or more treated with either FS-LASIK with cyclotorsion compensation or SMILE with stringent head positioning were included. The results of vision and refraction were analyzed and compared between groups with the right eye.ResultsThe study enrolled 94 patients (41eyes in an FS-LASIK with compensation of cyclotorsion group and 53 eyes in a SMILE with stringent head positioning control group. The mean preoperative manifest cylinder was -2.65 ± 0.77D in the FS-LASIK group and 2.51 ± 0.56D in the SMILE group (P = 0.302). At 12 months, there was no significant between-group difference in uncorrected distance visual acuity (UDVA, P = 0.274) and postoperative spherical equivalent (SEQ) (P = 0.107). 46.3% and 24.5% of eyes in the FS-LASIK and SMILE groups were within 0.25 D were within 0.25D postoperative cylinder, respectively, and 78% and 66% of eyes in these two groups were within 0.5 D postoperative cylinder (P = 0.027, P = 0.202). The vector analysis showed comparable between-group target-induced astigmatism (TIA) (P = 0.114), surgically induced astigmatism (SIA) (P = 0.057), difference vector (DV, P = 0.069), and the angle of error (AE) (P = 0 .213) values. The index of success (IOS) was 0.18 in the FS-LASIK group and 0.24 in the SMILE group (P = 0.024), with a significant difference between the two groups.ConclusionFS-LASIK with compensation of cyclotorsion showed a favorable correction of high myopic astigmatism (≥ 2.0 D) compared to SMILE with stringent head positioning at 12 months.

Influence of Ocular Residual Astigmatism and Target-Induced Astigmatism on the Efficacy of the Implantation of a Toric Implantable Collamer Lens With Central Hole for Myopic Astigmatism Correction.

PurposeTo investigate the effects of ocular residual astigmatism (ORA) and target-induced astigmatism (TIA) on the efficacy of toric implantable collamer lens (TICL) with central hole for myopic astigmatism correction.MethodsRetrospective case series. One hundred and eighteen eyes implanted with a TICL (V4c) from 118 patients were included. Subjective refraction and corneal topography were examined preoperatively, at 1 and 12 months postoperatively. The eyes were divided into the low-ORA ( ≤ 0.5 D) and high-ORA (>0.5 D) groups based on vector analysis, and into the low-TIA (≥0.75D and <2 D) and the high-TIA (≥2 D and ≤ 4 D) groups according to preoperative refractive astigmatism. Correction index (CI) and index of success (IOS) were compared between different groups.ResultsAll surgeries were uneventful, and no complications occurred during follow-up. At 1 and 12 months postoperatively, no significant differences were found in CI or IOS values between the high and low ORA groups, while significantly higher CI and lower IOS were detected in the high-TIA group than in the low-TIA group (P < 0.05). No significant difference was found in CI between 1 and 12 months postoperatively in either group (P > 0.05). However, significantly lower IOS was found at 12 months compared with 1 month postoperatively for each group (P < 0.05).ConclusionsToric implantable collamer lens (TICL) implantation is effective in correcting myopic astigmatism and is more effective in eyes with high TIA, while ORA has a minor effect.

Treatment of corneal astigmatism by limbal relaxing incisions during phacoemulsification surgery

Background and aim The aim was to assess the effectiveness of limbal relaxing incisions (LRIs) in treatment of astigmatism in patients undergoing phacoemulsification surgeries. Patients and methods Forty-eight eyes of 48 patients suffering from senile cataracts of mean age 64.7±7.9 (range: 50–77) years, and mean corneal astigmatism 1.8±0.73 diopters (D) (range: 1.5–3.5 D) were included in this study. All LRIs were performed at the end of phacoemulsification. Corneal topography results were compared before surgeries and 2 and 6 months after surgeries. Results A statistically significant reduction in the mean corneal astigmatism was seen from 1.8±0.73 D (range: 1.50–3.50) preoperatively to 1.1±0.24 D (range: 0.5–1.7) and 1.4±0.52 D (range: 0.60–1.9) in the second and sixth postoperative months, respectively (P&lt;0.001). Surgical-induced astigmatism (the amount and axis of astigmatism change induced by surgery) was 0.90±0.48 at 2 months and 0.96±0.59 at 6 months. Correction index (calculated by determining the ratio of surgical-induced astigmatism/target-induced astigmatism) was 0.56±0.42 and 0.57±0.33 at 2 and 6 months, respectively. Index of success (ratio of topographic residual astigmatism and target-induced astigmatism) was measured to be 0.45±0.42 and 0.48±0.33 at months 2 and 6 correspondingly. Conclusion Combined LRI and phacoemulsification appears to be safe and fairly effective to correct mild-to-moderate corneal astigmatism. However, undercorrection is a common limitation that may be further managed by modified nomograms in future studies.

Astigmatism Correction during Femtosecond Laser-assisted Transepithelial Arcuate Keratotomy Using the Wound Open Method

Purpose: The purpose of this study was to compare corneal astigmatism correction between “wound open” and “wound intact” methods during femtosecond laser-assisted transepithelial arcuate keratotomy.Methods: From April 2016 to December 2018, a retrospective survey was conducted on patients undergoing femtosecond laser cataract surgery at the Ophthalmology Department of Samsung Medical Center. Size comparison and vector analysis of corneal astigmatism before and after surgery were performed in the wound open and wound intact groups.Results: In the wound open and wound intact groups, the target-induced astigmatism (TIA) was 1.28 ± 0.55; and 1.26 ± 0.29 diopters, the surgically induced astigmatism (SIA) was 0.80 ± 0.52; and 0.53 ± 0.32 diopters, and the correction index (CI) was 0.63 ± 0.28; and 0.43 ± 0.26, respectively. The astigmatism correction was superior in the wound open group (p = 0.048, p = 0.025). In a subgroup with TIA &lt; 1.2 diopters, there were no significant differences in SIA or CI between the two groups; however, in the subgroup with a TIA &gt; 1.2 diopters, the SIA was 1.09 ± 0.59; and 0.54 ± 0.37 diopters and the CI was 0.60 ± 0.28; and 0.36 ± 0.23 in the wound open and wound intact groups, respectively (p = 0.022, p = 0.047). Thus, astigmatism correction was superior in the wound open group.Conclusions: The wound open method during femtosecond laser-assisted transepithelial arcuate keratotomy was superior for astigmatism correction compared to the wound intact method.

Comparison of penetrating femtosecond laser-assisted astigmatic keratotomy and toric intraocular lens implantation for correction of astigmatism in cataract surgery

This study tried to compare the clinical outcomes of femtosecond laser-assisted astigmatic keratotomy (FSAK) and toric intraocular lens (IOL) implantation for astigmatism correction and identify factors affecting the efficacy of FSAK and toric IOL implantation in astigmatism correction. This retrospective case series comprised patients with corneal astigmatism ranging between 0.5 D and 4.5 D. Patients underwent FSAK or toric IOL implantation for cataract treatment and correction of astigmatism at the Samsung Medical Center, a tertiary surgical center, between April 2016 and December 2018. All patients underwent examination before and at three months after the surgery for comparative evaluation of refractive astigmatism, corneal high order aberrations and irregularity index. The astigmatism correction was analyzed by the Alpins method. Subgroup analysis of preoperative factors was based on the extent of target-induced astigmatism (TIA), the degree of astigmatism, and astigmatism classification based on topography. Thirty-one eyes underwent toric IOL implantation and 35 eyes underwent FSAK. The refractive astigmatism was significantly decreased in both toric IOL (P = 0.000) and FSAK group (P = 0.003). The correction index (CI) of refractive astigmatism was 0.84 ± 0.39 in the toric IOL and 0.71 ± 0.60 in the FSAK group. There was no difference between the two groups (P = 0.337). The CI of the FSAK group was significantly lower than in the toric IOL group when TIA was more than 1.5 D (P = 0.006), when correcting against-the-rule (P = 0.017), and limbus-to-limbus astigmatism (P = 0.008). In conclusion, toric IOL implantation is an effective and safe procedure for correcting preoperative astigmatism in cataract surgery in the short-term observation.

Comparison of corneal aberrations and refractive outcomes after small-incision lenticule extraction and femtosecond-assisted laser-assisted in situ keratomileusis.

To retrospectively compare the short-term refractive outcomes and corneal aberrations after small-incision lenticule extraction (SMILE) and femtosecond-assisted laser-assisted in situ keratomileusis (FS-LASIK) combined with smart pulsetechnology (SPT) in patients with compound myopicastigmatism. A total of 91 eyes (91 patients) were included, 43eyes in FS-LASIK group and 48 eyes in the SMILE group. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refractive results and corneal topography were evaluated 1 and 3months postoperatively. Corneal aberrations of anterior corneal surface were calculated from the topography data over 6mm-diameter. There was no significant difference in UCVA, BCVA, and refractive results between the two groups. There were no statistical difference in TIA (target induced astigmatism), SIA (surgery induced astigmatism), DV (difference vector), ME (magnitude of error), AE (angle of error), AE (absolute value) and CI (correction index) between both groups at 1 and 3months. Coma and spherical aberration improved in all the patients in both groups at 1 and 3months postoperatively. The amount of induced spherical aberrations was higher in FS-LASIK group compared to SMILE group. Both FS-LASIK and SMILE achieved similar refractive outcomes in patients with myopia and compound myopic astigmatism. FS-LASIK combined with SPT resulted in higher spherical aberration than SMILE in early postoperative period.

Astigmatism correction with toric implantable collamer lens in low and high astigmatism groups.

To analyze the target induced astigmatism (TIA), surgically induced astigmatism (SIA), difference vector (DV), and correction index (CI) in the correction of astigmatism with phakic lenses, and its influence on visual acuity, and to analyze the safety and efficacy indexes of the correction of high and low power astigmatism with toric phakic lenses. Retrospective comparative study. The medical records of patients that were operated on at the research center during the period were analyzed. Results were divided into Low Astigmatism Group - LAG (33 eyes) and High Astigmatism Group - HAG (93 eyes) according to the implanted toric ICL lens power. Preoperative refraction and resultant postoperative refraction were analyzed by vector analysis. Visual acuity pre and postop, with and without optical correction, were compared. A total of 126 eyes were studied. The average preop refraction was -5.02 D sphere with -2.61 D cylinder. The average ICL lens power implanted was -8.31 D sphere +2.77 D cylinder. Refractive remaining was -0.01 ± 0.11 D sphere -0.15 ± 0.28 D cylinder. The arithmetic average angle of error in the astigmatism correction was 1.08°. The resultant cylinder was -0.03 ± 0.12 D and -0.19 ± 0.30 D in the low and high astigmatism groups, respectively, with a mean UDVA -0.01 ± 0.10 and 0.01 ± 0.16 and CDVA -0.03 ± 0.08 and -0.01 ± 0.17 for each group. The safety and efficacy indexes for the low astigmatism group were 1.09 ± 0.16 and 1.05 ± 0.17, respectively, with 1.11 ± 0.17 and 1.06 ± 0.16 for the high astigmatism group. The correction of astigmatism by the implantation of toric phakic lenses of the posterior chamber is safe and effective, independently of the amount of cylinder corrected.

Evaluation of Astigmatic Correction Using Vector Analysis after Combined Femtosecond Laser-Assisted Phacoemulsification and Intrastromal Arcuate Keratotomy.

The aim of this study was to evaluate astigmatic correction in patients with mild to moderate astigmatism after combined femtosecond laser-assisted cataract surgery (FLACS) and intrastromal arcuate keratotomy (ISAK), using vector analysis. This retrospective study included patients with corneal astigmatism of 0.5–3.0 diopters (D) who underwent FLACS and ISAK. Vector analyses of astigmatism were performed using the Alpins method, considering three vectors: target-induced astigmatism (TIA), surgically induced astigmatism (SIA), and difference vector (DV). Magnitude of error (ME), angle of error (AE), correction index (CI), and coefficient of adjustment (CA) were calculated. Subgroup analysis according to the axis of astigmatism, patient age, and white to white (WTW) diameter was conducted. In total, for the 79 eyes of 79 patients, the TIA was 1.21 ± 0.52 D, the SIA was 0.76 ± 0.53 D, and the DV was 0.86 ± 0.50 D. The ME (difference between SIA and TIA) was −0.46 ± 0.45 D, and the CI (ratio of SIA and TIA) was 0.62 ± 0.34; both these parameters demonstrated slight undercorrection. The CA (inverse of the CI) was 2.48 ± 2.61. The AE was 4.02° ± 28.7°, and the absolute AE was 21.7° ± 19.0°. In the univariate regression analyses to identify factors that affected the CI, there was a negative correlation between age and the CI (P=0.022). In conclusion, vector analysis after the combined FLACS and ISAK revealed slight undercorrection, regardless of the astigmatism meridian. The precision of the nomogram should be improved through long-term vector analysis for the results of arcuate keratotomy and through further research on the relationship between patient demographics and CI. Overall, this study has shown that FLACS and ISAK could reduce postoperative corneal astigmatism effectively and safely.