Surgically 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.

Comparison of Surgically Induced Astigmatism Following Manual Sics: Superior and Temporal Approach

Aim: The operable cataract cases in the developing world is high compared to the cataract surgical rate, and economical and effective methods are required to deal with this curable blindness, in order to provide the highest achievable uncorrected distance visual acuity. This study aimed to compare the surgically induced corneal astigmatism in patients undergoing manual small incision cataract surgery by superior (s-MSICS) and temporal (t-MSICS) scleral tunnel incisions. Methods: Prospective, interventional cases series of 60 eyes of 60 patients. Uncorrected distance visual acuity (UDVA), mean keratometry (KMean) and surgically induced astigmatism (SIA) were the main outcome measures which were compared between the two groups, s-MSICS and t-MSICS. Results: The mean patient age was 58.60 ± 7.11 years and 59.63 ± 8.39 years in the s-MSICS and t-MSICS groups respectively. Uncorrected distance visual acuity (UDVA) on day 90 was 0.27 ± 0.14 logMAR in the s-MSICS group and 0.18 ± 0.16 logMAR in the t-MSICS group (p=0.05). At the final assessment s-MSICS had 1.43 ± 0.99D of SIA and t-MSICS had 0.76 ± 0.66D of SIA (p=0.02). Four patients in the s-MSICS group and 25 patients in the t-MSICS group had WTR astigmatism (p&lt;0.001). Likewise, there were 26 cases of ATR and one case of ATR in the s-MSICS and t-MSICS respectively (p&lt;0.001). Conclusion: In this prospective study, t-MSICS had significantly lesser surgically induced astigmatism than s-MSICS. The temporal incision decreased against the rule astigmatism, as well, which is the astigmatism prevalent in the adult population.

Comparison of short-term clinical outcomes of a diffractive trifocal intraocular lens with phacoemulsification and femtosecond laser assisted cataract surgery

PurposeTo evaluate short-term visual and refractive outcomes after implantation of a diffractive trifocal intraocular lens (IOL) in cataract patients with phacoemulsification (PHACO) and femtosecond laser assisted cataract surgery (FLACS).SettingDepartment of Ophthalmology, Shanghai Aier Eye Hospital, China.DesignA retrospective, observational study.MethodsPatients who underwent cataract surgery combined with Acrysoft IQ PanOptix trifocal IOL implantation were enrolled and divided into three groups: PHACO group, LAstig-FLACS group (astigmatism less then 1D) and HAstig-FLACS group (astigmatism more than 1D). Logarithm of the minimum angle of resolution (logMAR) visual acuity of uncorrected distance (UDVA), intermediate (UIVA), near visual (UNVA), defocus curve, surgically induced astigmatism (SIA) were evaluated in 1 months postoperatively and wavefront aberrations were evaluated in 6 months.Results101 eyes of 60 patients were included with 31 eyes in PHACO group, 45 eyes in LAstig-FLACS group and 25 eyes in HAstig-FLACS group. Significant difference was found of internal Strehl Ratio (SR) between PHACO and LAstig-FLACS group (P = 0.026). In PHACO group, 79.31%, 86.21%, 72.41% of eyes gain visual acuity LogMAR 0.1 or more in UDVA, UIVA and UNVA, while 83.72%, 93.02%, 93.02% of those in LAstig-FLACS group and 92.00%, 84.00%, 76.00% in HAstig-FLACS group.ConclusionsPanoptix diffractive trifocal IOL provides satisfied visual outcome in no matter FLACS or PHACO. Besides, trifocal IOL implantation via FLACS can provide a better accumulative visual acuity outcome at all distance than PHACO in 1 month. Femtosecond laser assisted limbal relaxing incisions (FLLRIs) is an excellent way to reduce a patient’s corneal astigmatism.

Surgically induced astigmatism in the scleral fixated 'Carlevale' IOL technique.

To evaluate the surgically induced astigmatism over a 6-month follow-up period in patients who underwent scleral IOL fixation using an acrylic single-piece IOL with special haptics designed for sutureless scleral fixation. We conducted a prospective longitudinal study at a single site with a single surgeon. We included patients who received transscleral IOL implantation following the Carlevale technique and were followed up post-operatively for 24 weeks. We measured the patient's refraction at baseline, week 12 and week 24 using the best corrected visual acuity at 4 m (EDTRS chart). We performed corneal tomography at every visit using an anterior segment optical coherence tomography (AS-OCT). We evaluated surgically induced astigmatism (SIA) and refraction during each follow-up visit and compared them to baseline. We then assessed changes in SIA over time. In total, 27 eyes of 27 patients consisting of 16 female and 11 male individuals were evaluated. The mean patient age was 71 ± 11.7 years, mean axial length was 24.30 ± 1.47 mm (range: 21.4-27.23) and mean white-to-white distance was 12.07 ± 0.40 mm (range: 11.4-12.7). The mean SIA decreased from 1.78 ± 0.96D at week 1 significantly to 0.80 ± 0.55D at week 12 (p < 0.001) and then stayed unchanged around 0.82 ± 0.72D at week 24 (p = 1.0). The scleral fixated Carlevale IOL and its implantation procedure were found to result in a predictable SIA of <1D after 24 weeks. However, the axis orientation of the SIA appeared to be random, making it unsuitable for implementation in toric IOL calculations.

Effects of reduction in intraocular pressure after trabeculotomy on axial length and intraocular lens selection.

To investigate the relationship between intraocular pressure (IOP) and axial length (AL) and to compare the refractive predicted error in patients who have undergone cataract surgery alone or in combination with trabeculotomy. Hospital. Single-center, retrospective, case-control. The medical records of patients who had undergone cataract surgery alone or in combination with trabeculotomy using the Tanito microhook were retrospectively reviewed. Patients were grouped into cataract surgery alone (CAT) or cataract surgery combined with trabeculotomy (LOT) groups. Demographic data, preoperative and postoperative IOP and AL, and surgically induced astigmatism (SIA) were analyzed before and 1 month postoperatively to evaluate the interplay between IOP, AL, and refractive outcomes. 52 eyes (52 patients) underwent LOT, and 67 eyes (67 patients) underwent CAT. The mean IOP at baseline did not differ between the groups; the change in IOP (dIOP) was significantly higher in the LOT group than in the CAT group. The mean AL at baseline and the change in AL (dAL) were 24.0 ± 1.2 mm and 0.16 ± 0.11 mm, respectively, in the LOT group, and 23.8 ± 1.1 mm and 0.11 ± 0.070 mm, respectively, in the CAT group. The difference in dAL was also significant. In the LOT group, dIOP and dAL were significantly correlated. The mean SIA vectors did not significantly differ between the groups. AL decreased because of the reduction in IOP after cataract surgery combined with trabeculotomy. Consequently, the refractive target error was greater, and the postoperative refractive outcome showed a tendency toward hyperopia.

Comparison of Clinical Outcomes Among Sutured, Sutureless Scleral Fixation, and Retropupillary Fixation of Intraocular Lens

Purpose: To compare the short-term clinical outcomes (up to 3 months) after three different secondary intraocular lens (IOL) implantations in dislocated and aphakic eyes with insufficient capsular support.Methods: We retrospectively analyzed the medical records of 97 patients who underwent secondary IOL implantation (32 eyes with sutured scleral fixation, 21 with sutureless scleral fixation, and 44 with retropupillary IOL implantation) from March to December 2018. Uncorrected visual acuity (UCVA), and best-corrected visual acuity (BCVA), spherical equivalent (SE), prediction error (PE), mean absolute error (MAE), surgically induced astigmatism (SIA), ocular residual astigmatism (ORA), and complications in the three groups were assessed before and 1 week and 1 and 3 months after surgery.Results: All groups had an improved BCVA beginning 1 month after surgery. The pre- and postoperative SE (&lt;i&gt;p&lt;/i&gt; = 0.857, &lt;i&gt;p&lt;/i&gt; = 0.263, and &lt;i&gt;p&lt;/i&gt; = 0.163) and PE (&lt;i&gt;p&lt;/i&gt; = 0.479, &lt;i&gt;p&lt;/i&gt; = 0.848, and &lt;i&gt;p&lt;/i&gt; = 0.128) did not differ in the sutured scleral fixation, sutureless scleral fixation, and retropupillary IOL implantation groups, respectively; MAE differed significantly among the procedures 1 week after surgery (1.33 ± 1.25, 1.40 ± 1.54, and 0.85 ± 1.25, &lt;i&gt;p&lt;/i&gt; = 0.044), but not 1 month after surgery (&lt;i&gt;p&lt;/i&gt; = 0.965, &lt;i&gt;p&lt;/i&gt; = 0.731). 3 months after surgery, there was no significant difference in SIA (&lt;i&gt;p&lt;/i&gt; = 0.140) or ORA (&lt;i&gt;p&lt;/i&gt; = 0.178) among the 3 groups. As a complication, intraocular pressure rise occurred more often in the sutured fixated group, while the retropupillary group had a higher dislocation rate.Conclusions: There was no significant difference in the SE, PE, MAE, SIA, ORA, or complications among the three procedures. Surgical skill is still required to minimize the chance of complications regardless of the implantation method.

Visual outcome and complications of phacoemulsification and manual small incision cataract extraction for age related cataract

The purpose of this study is to compare visual outcome and complications of manual small incision cataract surgery (MSICS) with posterior chamber IOL implantation (PC-IOL) and phacoemulsification with posterior chamber IOL implantation for age related cataract. The study compares the visual outcome and complications of MSICS and phacoemulsification with PC-IOL performed in 80 eyes at M &amp; J Western Regional Institute of Ophthalmology (M&amp;J WRIO) Ahmedabad, by assessing post operative Best corrected Visual acuity (BCVA), Surgically Induced astigmatism (SIA) and complications. This was an Institutional based cohort interventional randomized, prospective study. MSICS and Phacoemulsification was performed on 80 eyes at M &amp; J WRIO. The intraoperative complications were documented. The parameters that were examined on 1 postoperative day, 1 week, and 6 weeks postoperatively included uncorrected visual acuity, best corrected visual acuity (BCVA) at 6 weeks, intra ocular pressure by non -contact tonometry and keratometry at 6 weeks to rule out SIA.Statistical analysis was performed using chi square test. p value &amp;#60;0.05 was taken as significant.: MSICS &amp; phacoemulsification had similar visual outcomes post-operatively. Phacoemulsification group produced less mean SIA (1.27 D) compared to MSICS group (1.29 D) and lesser (5%) complications than the MSICS group (10%). The comparison of all three parameters was not statistically significant between the two groups.: Visual outcomes, SIA and complications were comparably the same in MSICS &amp; phacoemulsification. Therefore, MSICS can be excellent alternative to phacoemulsification.

Measurement of the distance between corneal apex and pupil center in patients following small-incision lenticule extraction or implantable collamer lens implantation and its correlation with the surgical-induced astigmatism

BackgroundTo investigate the change in the distance between corneal apex and pupil center after small-incision lenticule extraction (SMILE) or implantable collamer lens (ICL) implantation and its correlation with surgical-induced astigmatism (SIA).MethodsThis study included patients who had undergone SMILE (n = 112) or ICL implantation (n = 110) to correct myopia and myopic astigmatism. The angle kappa was measured using a Scheimpflug imaging device (Pentacam) and represented as Cartesian values between the pupil center and the corneal vertex (X, Y) and chord u (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\sqrt{{X}^{2}+{Y}^{2}}@ $$\\end{document}orientation), and was compared pre- and post-operative.ResultsFollowing SMILE, the magnitude of chord u\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ (\\sqrt{{X}^{2}+{Y}^{2}}$$\\end{document}) significantly increased in both eyes (Wilcoxon signed-rank test, OD: P<0.001; OS: P=0.007), while no significant change was observed in the orientation. A significant correlation was found between the J0 component of SIA and the change in the magnitude of chord u for both eyes (OD: R2=0.128, P<0.001; OS: R2=0.033, P=0.004). After ICL implantation, the orientation of the chord u was significantly different in the right eye (Wilcoxon signed-rank test, P = 0.008), and the Y-intercept significantly decreased in both eyes (Wilcoxon signed-rank test, P<0.001). A significant correlation was found between J0 of SIA and the change in the magnitude of chord u for the right eyes (R2=0.066, P=0.002). A significant correlation was found between J45 of SIA and the change in the magnitude of chord u for the left eyes (R2=0.037, P=0.044).ConclusionsThe magnitude of the chord u increased following the SMILE procedure, whereas the Y-intercept significantly decreased after ICL implantation. SIA was related to the change in the magnitude of chord u.

The comparison of corneal higher-order aberration and surgically induced astigmatism between the clear corneal incision and the limbus tunnel incision of posterior chamber implantable collamer lens implantation

BackgroundThis study aimed to compare the corneal high-order aberrations and surgically induced astigmatism between the clear corneal incision and limbus tunnel incision for posterior chamber implantable collamer lens (ICL/TICL) implantation.MethodsA total of 127 eyes from 73 myopic patients underwent ICL V4c implantation, with 70 eyes receiving clear corneal incisions and 57 eyes receiving limbus tunnel incisions. The anterior and back corneal surfaces were measured and the Root Mean Square of all activated aberrations (TRMS) was calculated, including higher-order aberration (HOA RMS), spherical aberration Z40, coma coefficients (Coma RMS) Z3−1 Z31, and surgically induced astigmatism (SIA). The measurements were taken preoperatively and postoperatively at 1 day, 1 week, and 1, 3, and 6 months. In this study, the corneal higher-order aberration was estimated as the Zernike coefficient calculated up to 5th order. The measurements were taken at a maximum diameter of 6.5 mm using Pentacam.ResultsOne week after the operation, the corneal back Z31 of the clear corneal incision group was 0.06 ± 0.06, while the limbus tunnel incision group showed a measurement of 0.05 ± 0.06 (p = 0.031). The corneal back Z40 of the clear corneal incision group was -0.02 ± 0.25, compared to -0.04 ± 0.21 in the limbus tunnel incision group (p = 0.01). One month after the operation, the corneal back SIA of the clear corneal incision group was 0.11 ± 0.11, compared to 0.08 ± 0.11of the limbus tunnel incision group (p = 0.013), the corneal total SIA of the clear corneal incision group was 0.33 ± 0.30, compared to 0.15 ± 0.16 in the limbus tunnel incision group (p = 0.004); the clear corneal incision group exhibited higher levels of back astigmatism and total SIA than the limbus tunnel incision in the post-operation one month period. During the 6- month post-operative follow-up period, no significant difference in Z31, Z40, and other HOA RMS data was observed between the two groups. The total SIA of the corneal incision group and the limbus tunnel incision group were 0.24 ± 0.14 and 0.33 ± 0.32, respectively (p = 0.393), showing no significant difference between the two groups 6 months after the operation.ConclusionOur data showed no significant difference in the high-order aberration and SIA between clear corneal incision and limbus tunnel incision up to 6 months after ICL-V4c implantation.

Long Term Evaluation of Surgically Induced Astigmatism and Corneal Higher-Order Aberrations After 2.2 Mm Clear Corneal Incisions in Femtosecond Laser-Assisted Cataract Surgery: Temporal versus Superior Approach.

To assess long term changes of the surgically induced astigmatism (SIA) and corneal higher-order aberrations (HOAs) after 2.2 mm clear corneal incisions (CCIs) in femtosecond laser-assisted cataract surgery and compare them between 2 types of CCIs: temporal and superior approach. Patients received the temporal CCIs (Group A) or the superior CCIs (Group B). Outcome measures included visual acuity, manifest refraction, corneal astigmatism, SIA, flattening effect, and corneal HOAs. Correlation between postoperative corneal HOA and SIA at each follow-up were analysed. This study assessed data from 106 eyes, of which 64 in Group A and 42 in Group B. The two groups had similar postoperative visual acuity of distance, intermediate and near (all P > 0.05). SIA and corneal HOAs were significantly lower in Group A than Group B in the early postoperative period, while there was no significant difference in the late postoperative period. At 6 months after surgery, the arithmetic mean of SIA over corneal 4mm zone was 0.33 ± 0.19D for temporal incision, and 0.37 ± 0.25D for superior incision. For Group A, the correlations of HOAs and SIA persisted from 1 week to 6 months after surgery. For Group B, the changes in corneal HOAs were significantly related to the SIA at 1 week and 1 month postoperatively. This study suggested the consistency of increasing and recovering process of corneal HOAs and SIA after surgery. Compared to the superior incisions, temporal incisions might induce quicker corneal recovery and less change in SIA and corneal HOAs.

Clinical management of a nonoptimal vault and unexpected postoperative refraction in a patient implanted with a phakic intraocular lens

Introduction: This case reports the management of a bilateral toric implantable collamer lens (ICL) surgery with low vaulting and unilateral reduction in visual acuity (VA) associated with a combined effect of surgically induced astigmatism (SIA) and toric-ICL rotation. This case expands the common management of toric-ICL rotation, by adding surgically induced corneal changes. Patient and Clinical Findings: The patient presented with moderate myopia and high astigmatism and was implanted with a toric-ICL, resulting in bilateral low vault &lt;150 μm and unilateral VA reduction (20/40) because of postoperative oblique astigmatism, observed at the 4-week follow-up. Diagnosis, Intervention and Outcomes: The low ICL vaulting was associated with a high crystalline lens rise and underestimation of the sulcus-to-sulcus distance. The VA reduction resulted from a combined effect of ∼1.0 diopter SIA and 8-degree ICL rotation. The authors associate the high SIA to abnormal corneal biomechanics indexes and the toric-ICL rotation to a lack of stability resultant from a small ICL size. The left eye toric-ICL has exchanged with one with larger size and the power recalculated using vectorial analysis. The toric-ICL exchange increased the vault 75 μm and improved VA. Conclusions: Detailed anterior chamber morphometry and corneal biomechanics may assist in improving the refractive outcome in toric-ICL surgery.

Comparison of Corneal Endothelial Cell Loss during Manual Small-incision Cataract Surgery using Visco-expression versus Irrigating Wire Vectis-assisted Nucleus Removal: A Prospective Randomised Study

Introduction: Age-related cataract is the leading cause of curable blindness in India, and Manual Small-Incision Cataract Surgery (MSICS) is a machine-independent and cost-effective alternative to phacoemulsification for handling this significant burden. In every cataract surgery, some endothelial cell loss is inevitable. Therefore, the present study was conducted to compare endothelial cell loss in the two most commonly practiced methods of nucleus delivery in MSICS. Aim: To compare and analyse endothelial cell loss during MSICS using viscoelastic/viscoexpression-assisted nucleus removal versus irrigating wire vectis-assisted nucleus removal. Materials and Methods: A prospective randomised interventional study was conducted at the Regional Institute of Ophthalmology, Postgraduate Institute of Medical Sciences (PGIMS) Rohtak, Haryana, India. The study duration was three years, from May 2018 to May 2021. A total of 250 patients with uncomplicated senile cataract over 40 years of age, with nuclear sclerosis of grade 2 or higher and “with the rule” astigmatism, were included in the study. The patients were randomly divided into Group A and Group B (125 each), who underwent MSICS using visco-expression (Group A) versus irrigating wire vectis-assisted (Group B) nucleus removal. Visual Acuity (VA), keratometry, astigmatism, pachymetry, and Endothelial Cell Density (ECD) were recorded in every patient preoperatively and postoperatively on day 1 and day 40. The Shapiro-wilk test was used to assess the normality of the data, and student’s t-test was performed to identify significant differences in continuous factors between the two groups. Chi-square test was used to find the association between factors and techniques, with a p-value &lt;0.05 considered statistically significant. Results: The mean age of the patients was 68.5±9.4 years (range 52-89 years) with a significant male preponderance. The mean LogMAR visual acuity on Postoperative Day (POD)-1 was 0.3±0.1 for Group A, while for Group B, it was 0.5±0.2, showing a statistically significant difference (p=0.004). However, on day 40, visual acuity was comparable in both groups, with Group A (0.1±0.2) and Group B (0.1±0.1), and no significant difference (p=0.09). On POD-1, the percentage change in Endothelial Cell Density (ECD) was 4.2% in Group A and 10.6% in Group B, with a statistically significant difference (p=0.0017). On day 40, it was 2.1% and 4.8% in Group A and Group B, respectively, also showing a statistically significant difference (p=0.003). On postoperative day 40, the mean Surgically Induced Astigmatism (SIA) in Group A and Group B was 0.67±0.24 and 0.74±0.41, respectively, but this difference was statistically insignificant (p=0.074). Intra and postoperative complications such as hyphema, iridodialysis, and corneal oedema were more common in Group B than Group A. Conclusion: The study concludes that there was a statistically significant endothelial cell loss in the irrigating wire vectisassisted nucleus delivery method compared to the viscoexpression of the nucleus during MSICS. The present method also showed delayed visual rehabilitation and a higher risk of intra and postoperative complications. Therefore, viscoexpression of the nucleus should be the preferred method of nucleus delivery in every MSICS where feasible.

Is Astigmatism Correction Necessary for Patients With Cataract Who Have Corneal Astigmatism of Less Than 0.75 D?

Purpose: To investigate the proportion of patients with predicted refractive astigmatism (PRA) of 0.75 diopters (D) or greater and associated risk factors among cataract surgery candidates with low corneal astigmatism. Methods: A retrospective cross-sectional study was conducted in Zhongshan Ophthalmic Center, Guangzhou, China. Patients with cataract who had preoperative simulated keratometric astigmatism of less than 0.75 D were recruited. The PRA was calculated by Barrett toric calculator using posterior corneal astigmatism (PCA) measured by the IOLMaster 700 (Carl Zeiss Meditec AG) and corneal surgically induced astigmatism (SIA). Two corneal incision locations (temporal [0°/180°], 135° incision) and varying magnitudes (0.10 to 0.60 D) were considered for SIA. Multiple logistic regression analysis was used to explore risk factors associated with PRA of 0.75 D or greater and build predictive model. Sensitivity analysis was performed using PRA threshold of 0.50 D. Results: A total of 1,750 eyes from 1,750 patients were included (mean age: 60.14 ± 13.24 years, 42.91% male, 1,010 right eyes and 740 left eyes). The 135° incision (odds ratio [OR]: 17.86) and against-the-rule (ATR) astigmatism (OR: 37.55) are the major risk factors for PRA of 0.75 D or greater. Higher simulated keratometric astigmatism (OR: 2.03), larger PCA (OR: 1.64), and surgically induced astigmatism (OR: 1.29) also significantly increased the risk of PRA of 0.75 D or greater. Nomogram model were constructed with an area under curve of 0.90. Conclusions: For patients with corneal astigmatism of less than 0.75 D, temporal incision and measured PCA is preferred. Those patients with ATR astigmatism should be considered for astigmatism correction when using a 135° incision. [ J Refract Surg . 2023;39(12):850–855.]

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.

Online intraocular lens calculation.

To showcase the majority of online intraocular lens (IOL) calculation tools and highlight some of their characteristics. Online tools are available for preoperative and postoperative IOL-related calculations, including IOL power and toricity selection for standard patients, patients who underwent prior refractive surgery, keratoconus, limbal relaxing incisions for astigmatism management, realignment of a misplaced or rotated toric IOL, surgical induced astigmatism (SIA), formulae comparison, and other tools. As there are new online developments and technology is advancing rapidly, we hope that this review will assist ophthalmologists in becoming acquainted with a large variety of online tools.

Comparative Evaluation of Astigmatic Changes Induced by Superior and Temporal Corneal Incisions in Sutureless Phacoemulsification Surgery: A Case Series.

Background In cataract surgery, the effect of corneal incision astigmatism has been widely recognized for many years. The incision's size, shape, and location can all impact the patient's postoperative visual outcomes. Currently, phacoemulsification is considered the most preferred surgical technique for cataract extraction. However, there is still some debate about whether temporal incisions, which are smaller and considered nearly astigmatic neutral, result in more astigmatism than other incisions. As a result, it is important to continue studying the refractive changes induced by corneal incisions made at different sites during phacoemulsification surgery. Aim and objective To compare the incidence, extent, and course of postoperative astigmatic changes associated with superior versus temporal clear corneal incisions for sutureless phacoemulsification cataract surgery. Materials and method In this prospective study, 50 patients of the civil hospital in Gujrat with cataracts who underwent sutureless, small incision (2.8 mm) phacoemulsification surgery were included. The preoperative evaluation comprised visual acuity assessment, refraction, keratometry, fundus examination, and intraocular lens (IOL) power calculation. The superior incision was made in 25 patients, and the temporal incision was made in another 25 patients. Patients were examined preoperatively on day 1, at one week (day 7), after one month (day 30), and after two months (day 60). Result Postoperatively, two months (on day 60) postoperatively, in group A (superior approach), the mean surgically induced astigmatism (SIA) was 0.39±0.34 SD diopters, and in group B (temporal approach), it was 0.5±0.42 SD diopters. A significant statistical difference was not seen between these two groups. Conclusion Surgically induced astigmatism was minimal and comparable with both superior and temporal approaches to clear corneal incisions for phacoemulsification surgery.

Posterior keratometry changes after steep axis phacoemulsification: a prospective study.

Purpose: To measure changes in posterior corneal curvature after steep axis phacoemulsification and investigate the possibility of its effect on SIA. Methods: This was a prospective longitudinal study on 60 consecutive eyes of age-related cataract with regular astigmatism and absence of co-morbidities undergoing uneventful cataract surgeries with main incision at steep meridian. Preoperative and 4 weeks postoperative measurements of anterior and posterior corneal curvatures using Scheimpflug based corneal topographer were performed. Posterior corneal curvature was assessed at 3, 5- and 7-mm diameters. Results: The study found a statistically significant change in posterior corneal K1, K2 and mean astigmatism in all zones (3, 5 and 7 mm) at 4 weeks postoperative, when compared to preoperative readings. Conclusion: Posterior keratometry is likely to be an important determinant of Surgically Induced Astigmatism (SIA) and should be factored in for refractive cataract surgery.

Characteristics of surgically induced astigmatism after standardized microincisional cataract surgery with a superior limbal incision.

To determine (1) if measurements of surgically induced astigmatism (SIA) as measured by keratometry (K) and total keratometry (TK) differ (2) if SIA affects the magnitude and/or meridian of keratometric astigmatism (3) if SIA evolves over time. Tertiary care center. Retrospective data analysis. A swept-source optical coherence tomography biometry dataset (IOLMaster700) consisting of 498 eyes (327 patients) from a tertiary care center was analyzed. For all eyes preoperative and postoperative biometric measurements at 1-month, 3-month, and 6-months postoperative visits were considered for vector analysis of SIA K and SIA TK . Centroids in right and left eyes were 0.26 diopters (D) @5 degrees/0.31 D @1 degree for SIA K and 0.27 D @4 degrees/0.34 D @1 degree for SIA TK . Centroids for difference vectors K-TK in right and left eyes were 0.02 D @ 176 degrees/0.03 D @6 degrees. The mean SIA magnitudes in right and left eyes were 0.48 ± 0.41 D and 0.50 ± 0.37 D for SIA K and 0.53 ± 0.42 D and 0.54 ± 0.40 D for SIA TK . In eyes with ATR astigmatism, an increase in postoperative astigmatism magnitude was more common than a decrease. More than 30% of eyes showed changes in the meridian of more than 15 degrees. Overall, we observed differences in K- and TK-derived SIA, and changes in SIA magnitude over time. For postsurgical interventions, postoperative astigmatism meridian values should be measured to base treatments. Astigmatism magnitude showed a tendency to decrease for steep-meridian incisions and to increase in flat-meridian incisions.

Effect of long-term rotation on astigmatism following EVO-toric intraocular collamer lens implantation.

To evaluate the effect of long-term rotation on astigmatism following Evolution-toric intraocular collamer lens (EVO-TICL) implantation. Forty eyes of 22 patients were enrolled in this prospective study. Visual acuity, refractive parameters, and axial position of the EVO-TICL by OPD-Scan III aberrometer were measured preoperatively, 1 month and 3 years postoperatively. Last visit, the safety index was 1.32 ± 0.15 and the efficacy index was 1.01 ± 0.23. The best-fitting curve of the attempted versus achieved correction was y = 0.9751x + 0.001. The mean spherical equivalent (SE) decreased from -8.94 ± 2.72D preoperatively to 0.06 ± 0.24D and - 0.36 ± 0.46D 1 month and 3 years postoperatively, respectively. The mean target and surgical induced astigmatism were 1.55 ± 0.61D and 1.67 ± 0.94D 3 years postoperatively. The average expected axis of the TICL was-1.15 ± 9.07 (-21-19°). One month and 3 years postoperatively, the average actual axis was -0.70 ± 9.86 (-20-20°) and - 0.35 ± 11.72 (-25-30°), respectively. The absolute rotation of the TICL was 3.70 ± 4.42 (0-22°) and 6.00 ± 6.70 (0-32°) 1 month and 3 years postoperatively, respectively (p < 0.001). The expected astigmatism was -0.10 ± 0.12D, and the mean actual astigmatism was -0.21 ± 0.30D and - 0.44 ± 0.45D 1 month and 3 years postoperatively, respectively. The mean absolute rotation without postoperative astigmatism was 3.73 ± 2.69 (0-9°) and 1.67 ± 1.66 (0-5°) for low (<2D) and high (≥2D) astigmatic TICL, respectively (p < 0.05). EVO-TICL implantation is safe and effective, with good predictability and stability. OPD-Scan is a fast device to detect the axial position of the TICL without mydriasis, and the axial position is relatively stable in the long term postoperatively. A slight rotation of low-astigmatic TICL may not cause postoperative astigmatism, whereas rotation of the high-astigmatic TICL may cause it.

Analysis of Posterior Corneal Surgically Induced Astigmatism Following Cataract Surgery With a 1.8-mm Temporal Clear Corneal Incision.

To determine posterior corneal surgically induced astigmatism (SIA) when using a temporal clear corneal incision and the IOLMaster 700 (Carl Zeiss Meditec AG) for biometric measurements and to determine whether posterior corneal SIA can be predicted from preoperative data. A total of 258 consecutive eyes of 258 patients underwent cataract surgery with a 1.8-mm temporal clear corneal incision. Biometry measurements were taken preoperatively and 6 weeks postoperatively using the IOLMaster 700. Using vector analysis, the SIA of the posterior cornea was calculated. The centroid of posterior corneal SIA was 0.01 diopters (D) @159 ± 0.14 D. The mean posterior corneal SIA was 0.12 D ± 0.07 D. Posterior corneal SIA magnitude was 0.25 D or less in 95% of patients. There was no correlation found between posterior corneal SIA magnitude and any preoperative measurement. The authors suggest not adjusting for posterior corneal SIA if using a small caliber, temporal incision. It was not possible to predict posterior corneal SIA from preoperative biometric measurements. [J Refract Surg. 2023;39(6):381-386.].