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Since the first intraocular lens(IOL)was implanted by Harold Ridley in 1949 and the widespread use of depth-of-focus extended intraocular lens(EDOF IOL)clinically, the IOL has been constantly updated and developed, aiming to provide patients with good postoperative visual quality. The residual astigmatism is one of the important factors affecting the postoperative visual quality of cataract patients, 35%-40% of cataract patients have astigmatism of 1.00 D, and 19%-22% have astigmatism of 1.50 D. Therefore, it is important to understand the inclusiveness of EDOF IOL for astigmatism, so that the right IOL can be selected for the patient. This article summarizes the inclusiveness of different types of EDOF IOL for astigmatism and their advantages and disadvantages, with the expectation that it will provide a reference in selecting EDOF IOL for patients with different residual astigmatism.

Wilson Takashi Hida,1,2 Cesar Vilar,1,3 Bernardo Kaplan Moscovici,4,5 Antonio Francisco Pimenta Motta,3 Pedro Carlos Carricondo2 1Department of Ophthalmology, Hospital Oftalmológico de Brasília HOB, Brasilia, DF, Brazil; 2Department of Ophthalmology, University of Sao Paulo(USP), Rio de Janeiro, RJ, Brazil; 3Department of Ophthalmology, Renato Ambrosio Research Center CEORA, Rio de Janeiro, RJ, Brazil; 4Department of Ophthalmology and Visual Sciences, Federal University of São Paulo (UNIFESP), São Paulo, SP, Brazil; 5Department of Ophthalmology, Hospital Visão Laser, Santos, SP, BrazilCorrespondence: Wilson Takashi Hida, S GAS II St. de Grandes Áreas Sul 607 - Asa Sul, Brasília, DF, 70200-670, Brazil, Tel + 55 61 3686-4586, Email Takashi.doc@gmail.comPurpose: To validate a new methodology to evaluate the impact of astigmatism in pseudophakia using an astigmatic defocus curve.Setting: Hospital Oftalmológico de Brasilia, Brazil.Design: Non-randomized cohort study.Methods: For every point of the defocus curve, from − 2.00 to +3.00 with 0.50D intervals, visual acuity was assessed with optically induced astigmatism (0.50D, 1.00D and 1.50D at 90 and 180 degrees) in pseudophakic patients implanted with a refractive-enhanced intraocular lens.Results: Twelve patients were analyzed. A statistically significant difference was found between the 90° (ATR) and 180°(WTR) axis with 1.50D astigmatism, providing better visual acuity in ATR astigmatism (p < 0.05).Conclusion: This new methodology is reproducible, useful and may predict residual astigmatism tolerance in pseudophakic patients, which may help with surgery planning and IOL decision-making.Keywords: cataract, surgery, phacoemulsification, optics, residual astigmatism, visual performance

AIM: To investigate the effect of residual astigmatism on visual quality after phacoemulsification combined with regional refractive intraocular lens(IOL)implantation in patients with age-related cataract, and to evaluate the astigmatism inclusivity of regional refractive IOL.METHODS: Retrospective cohort study. The clinical data of 62 cases(73 eyes)of age-related cataract patients who underwent phacoemulsification combined with regional refractive IOL(Lentis Comfort LS-313 MF15)implantation from July 2020 to March 2022 at the ophthalmology department of our hospital were collected. They were grouped according to residual astigmatism at 6 mo postoperatively, taking 35 cases(40 eyes)with residual astigmatism of 0.75 D to 1.50 D as the experimental group, and 27 cases(33 eyes)with residual astigmatism ≤0.75 D as the control group. Visual acuity, defocus curves, objective visual acuity [wavefront aberrations, Strehl ratio(SR), modulation transfer functions(MTF)], subjective visual acuity(national eye institute visual function questionnaire-25), patients' satisfaction, and spectacle independence were compared between the two groups at 6 mo postoperatively.RESULTS:There was a difference in the preoperative astigmatism and the number of postoperative 6 mo residual astigmatism between the two groups(P0.05). The defocus curves showed that there was no difference in visual acuity between the two groups at all points in the +2.00 to -4.00 D defocus range of the additional spherical equivalent(P>0.05).CONCLUSION:Lentis Comfort LS-313 MF15 IOL was able to accommodate regular astigmatism of 1.50 D.

John So Min Chang,1 Sylvia Chui Ting Liu,1 Nadine Tsz Ching Ma,1 Jack Chun Man Ng2 1Department of Ophthalmology, Hong Kong Sanatorium & Hospital, Hong Kong; 2Department of Ophthalmology, Grantham Hospital, Hong KongCorrespondence: John So Min Chang, Department of Ophthalmology, Hong Kong Sanatorium & Hospital, Hong Kong, Tel +852 2835 8884, Fax +852 2835 8887, Email john.sm.chang@hksh.comPurpose: The effect of residual astigmatism and its axis on distance and near visual acuities (VAs) with multifocal intraocular lenses (IOLs) has not been studied extensively. This study compared the tolerance to experimentally induced residual astigmatism among bifocal, trifocal, and extended depth-of-focus (EDOF) IOLs.Patients and Methods: This retrospective, comparative study included 70 eyes of 70 patients implanted with bifocal, trifocal, or EDOF IOLs. Distance and near VAs were assessed with experimentally induced astigmatism by placing positive cylindrical lenses in increments of 0.50 diopters to 2.00 diopters at 90° and 180° axes over the best distance correction.Results: Both distance and near VAs worsened with increasing magnitudes of experimentally induced astigmatism except in the EDOF group, in which the near VA remained within a clinically acceptable limit, ie, within one line from the best corrected VA under all ranges of experimentally induced astigmatism. Furthermore, the EDOF group showed the highest astigmatic threshold for losing VA lines following experimental astigmatic induction at both distance and near. The distance VA was generally better at with-the-rule (WTR) than against-the-rule (ATR) astigmatism for all three IOL groups. On the other hand, the near VA was generally better at WTR than ATR astigmatism in the bifocal group, comparable between WTR and ATR astigmatism in the trifocal group, and generally better at ATR than WTR astigmatism in the EDOF group.Conclusion: The EDOF IOL demonstrated the highest tolerance to experimentally induced astigmatism at both distance and near. VA was generally less affected by WTR astigmatism than ATR astigmatism, especially at distance. We proposed the residual astigmatism thresholds for clinically acceptable VA reduction in all three IOL groups.Keywords: residual astigmatism, bifocal, extended depth-of-focus, trifocal

PurposeTo evaluate 3-month rotational stability, and visual and refractive outcomes of a toric intraocular lens (IOL) with frosted haptics.Patients and methodsA post-market, prospective, multi-center, single-arm, open-label study conducted at seven clinical sites in the United States. Two hundred and two eyes of 133 subjects with unilateral or bilateral cataracts and corneal astigmatism were implanted with the Tecnis Toric II IOL, Models ZCU150 to 600 (Johnson & Johnson Surgical Vision, Inc.). Lens axis misalignment/rotation, visual acuity, manifest refraction, and surgeon and patient satisfaction were evaluated 3 months postoperatively. Lens rotation was determined with operative and postoperative visit photographs and was analyzed by two independent masked analysts.ResultsMean absolute lens rotation was 0.82° ± 1.00° and 0.94° ± 0.71° at 1 day (n = 189 eyes) and 3 months (n = 185 eyes), respectively. Absolute lens rotation was ≤5° in 98.9% and 100% of eyes at 1 day and 3 months, respectively. At 3 months, postoperative monocular uncorrected and corrected distance visual acuities were 0.004 ± 0.115 LogMAR (20/20) and -0.066 ± 0.092 LogMAR (20/17), mean spherical equivalent was -0.25 D ± 0.35 D and residual refractive cylinder was +0.27 D ± 0.33 D. Surgeons were satisfied/very satisfied with overall clinical outcomes and rotational stability in 99% of eyes, and with uncorrected distance vision in 98.5% of eyes.ConclusionThe study results demonstrate that the Tecnis Toric II IOL has excellent rotational stability with a high percentage of study eyes being within 5° of intended orientation. The study lens demonstrated excellent uncorrected distance visual acuity, reduction of cylinder, and exceptional patient and surgeon satisfaction.

AIM: To investigate the visual quality of LENTIS Comfort Toric intraocular lens implantation in cataract surgery.METHODS: A retrospective controlled clinical study was conducted on 40 patients(40 eyes)who received phacoemulsification combined with intraocular lens implantation assisted by digital navigation, with LENTIS Comfort Toric(MF15T)implanted in group A(24 eyes)and monofocal Toric intraocular lens implanted in group B(16 eyes). The visual acuity at different distances, the postoperative astigmatism center of mass value, the lens loss rate, the change of defocus curve and the stability of intraocular lens were observed at 3mo after surgery.RESULTS: There were no serious complications in both groups, and there was no significant difference in distance vision between group A and group B at 3mo after surgery(P>0.05); the visual acuity and near vision in group A were significantly better than those in group B(P0.05); the defocus curve of group A peaked at +0.50 and -1.75D at 3mo after surgery, forming plateau and gently declining, while group B showed a steep decline after peaks at +0.25 and -0.25D. One eye(4%)in group A had the axial rotation of intraocular lens greater than 10° at 1d after surgery; In group B, 6 eyes(38%)had axial rotation of intraocular lenses greater than 10°, 2 eyes(33%)rotated clockwise, and 4 eyes(67%)rotated counterclockwise. No intraocular lens displacement occurred in either group.CONCLUSION: Both kinds of intraocular lenses can correct astigmatism, among which LENTIS Comfort Toric intraocular lens can provide personalized choices for people with cataract and astigmatism, solve astigmatism and obtain full visual acuity at the same time, with low incidence of postoperative optical interference, better stability, high visual quality and satisfaction.

Purpose: To evaluate residual refractive astigmatism using the Panacea and enVista toric calculators, compared to the gold-standard Barrett toric calculator. Design: A retrospective and comparative study was conducted in one center. Methods: We reviewed the medical records of all patients with a diagnosis of senile cataracts and regular corneal astigmatism, without previous corneal or intraocular surgery, who underwent phacoemulsification with implantation of a toric intraocular lens, who had pre- and postoperative corneal topography, biometry, and refraction measurements. Results: The frequency of preoperative astigmatism according to the axis was 70 (84%) eyes showing with-the-rule (WTR) astigmatism, 9 (14%) eyes with against-the-rule (ATR) astigmatism, and 1 (2%) eye with oblique astigmatism. Regarding astigmatism prediction errors, there were statistically significant differences between the enVista and Panacea calculators (median of 0.39, 0.18, and 0.52 for Barrett, enVista, and Panacea, respectively). The residual astigmatism prediction error centroid was similar for the Barrett and enVista toric calculators, and both were lower compared to the Panacea calculator (x-component p < 0.001). Conclusions: The enVista toric calculator incorporating the Emmetropia Verifying Optical (EVO) toric calculator provides similar results to the gold-standard Barrett calculator. [ABSTRACT FROM AUTHOR]

Daniel H Chang,1 Jerry Hu,2 Kevin M Miller,3 Srividhya Vilupuru,4 Wuchen Zhao4 1Empire Eye and Laser Center, Bakersfield, CA, USA; 2Texas Eye & Laser Center, Hurst, TX, USA; 3Department of Ophthalmology, David Geffen School of Medicine at the University of California Los Angeles (UCLA), Los Angeles, CA, USA; 4Johnson & Johnson Surgical Vision, Inc., Irvine, CA, USACorrespondence: Daniel H Chang, Empire Eye & Laser Center, 4105 Empire Dr, Bakersfield, CA, 93309, USA, Email dchang@empireeyeandlaser.comPurpose: To evaluate 3-month rotational stability, and visual and refractive outcomes of a toric intraocular lens (IOL) with frosted haptics.Patients and Methods: A post-market, prospective, multi-center, single-arm, open-label study conducted at seven clinical sites in the United States. Two hundred and two eyes of 133 subjects with unilateral or bilateral cataracts and corneal astigmatism were implanted with the Tecnis Toric II IOL, Models ZCU150 to 600 (Johnson & Johnson Surgical Vision, Inc.). Lens axis misalignment/rotation, visual acuity, manifest refraction, and surgeon and patient satisfaction were evaluated 3 months postoperatively. Lens rotation was determined with operative and postoperative visit photographs and was analyzed by two independent masked analysts.Results: Mean absolute lens rotation was 0.82° ± 1.00° and 0.94° ± 0.71° at 1 day (n = 189 eyes) and 3 months (n = 185 eyes), respectively. Absolute lens rotation was ≤ 5° in 98.9% and 100% of eyes at 1 day and 3 months, respectively. At 3 months, postoperative monocular uncorrected and corrected distance visual acuities were 0.004 ± 0.115 LogMAR (20/20) and − 0.066 ± 0.092 LogMAR (20/17), mean spherical equivalent was − 0.25 D ± 0.35 D and residual refractive cylinder was +0.27 D ± 0.33 D. Surgeons were satisfied/very satisfied with overall clinical outcomes and rotational stability in 99% of eyes, and with uncorrected distance vision in 98.5% of eyes.Conclusion: The study results demonstrate that the Tecnis Toric II IOL has excellent rotational stability with a high percentage of study eyes being within 5° of intended orientation. The study lens demonstrated excellent uncorrected distance visual acuity, reduction of cylinder, and exceptional patient and surgeon satisfaction.Keywords: toric IOL, lens rotation, IOL misalignment, residual astigmatism

IntroductionAstigmatism reduces the postoperative visual performance after non-toric intraocular lenses (IOLs) implantation, and limits the use of refractive IOLs in cataract surgery. The purpose of this study was to compare the efficacy in astigmatism correction and the postoperative visual outcomes between the implantation of a trifocal IOL with femtosecond laser-assisted arcuate keratotomy (FSAK) in one eye and a bifocal toric IOL (TIOL) in the other, in patients with cataract and moderate astigmatism.MethodsThis prospective observational paired-eye study enrolled patients with cataract and corneal astigmatism (CA) between 0.75 and 2.25 D in both eyes. The patients underwent a mix-and-match treatment comprising trifocal IOL implantation with FSAK and bifocal TIOL implantation. We compared the visual acuity (VA) at all distances, defocus curve, postoperative refractive astigmatism (RfA), CA, high-order aberrations, modulation transfer function (MTF) curve, and Strehl ratio between the two eye groups.ResultsIn total, 41 patients (82 eyes) were enrolled and completed a 6-month follow-up. The 1- and 3-month uncorrected distance VA and 3-month uncorrected near VA were greater in eyes with bifocal TIOLs than with trifocal IOLs and FSAK (p = 0.036, 0.010, and 0.030, respectively), whereas the latter had greater uncorrected intermediate VA at every visit and greater VA in the intermediate range of defocus curve (at −1.50 and − 2.00 D) than the eyes with bifocal TIOLs. The postoperative RA of the eyes with trifocal IOL and FSAK was significantly higher than that of the bifocal TIOL-implanted eyes at the 3- and 6-month follow-ups.DiscussionBoth FSAK and TIOL implantation effectively reduce pre-existing moderate astigmatism in patients with cataract. The eyes with bifocal TIOLs had more stable long-term astigmatism correction, whereas those with trifocal IOLs and FSAK had better intermediate VA. Therefore, a mix-and-match implantation of trifocal IOL with FSAK and contralateral bifocal TIOL could achieve effective astigmatism correction and provide an overall optimal VA.

Keizo Watanabe Minami Osaka Eye Clinic, Osaka, JapanCorrespondence: Keizo Watanabe, Minami Osaka Eye Clinic, Osaka, Japan, Tel +81 072-453-1750, Email nabedosu@outlook.comPurpose: To assess the refractive accuracy of the intraoperative aberrometer Optiwave Refractive Analysis (ORA) and evaluate factors impacting residual astigmatism in eyes implanted with PanOptix (TFNT) trifocal intraocular lenses (IOLs) during cataract surgery.Patients and Methods: This retrospective study examined 180 eyes implanted with a toric or non-toric trifocal IOL during cataract surgery. The mean refractive prediction error (RPE), median absolute RPE, and percentage of eyes with an absolute RPE ≤ 0.25, ≤ 0.50, ≤ 0.75, and ≤ 1.00 diopter (D) were determined for ORA and each of the IOL power formulas (Sanders–‍Retzlaff–Kraft/Theoretical [SRK/T], Barrett Universal II, and Haigis). Correlation analysis of postoperative residual astigmatism and factors associated with it was performed using Pearson’s and Spearman correlations in eyes with non-toric trifocal IOLs.Results: After optimization, the median absolute RPE was 0.19 D, 0.25 D, 0.20 D, and 0.26 D in eyes measured using ORA and the SRK/T, Barrett Universal II, and Haigis formulas, respectively. An absolute RPE ≤ 0.50 D after optimization was noted in 92.8%, 83.3%, 88.3%, and 81.1% of the eyes using ORA and the SRK/T (p=0.0093), Barrett Universal II (p=0.2071), and Haigis (p=0.0018) formulas, respectively, showing significant differences between ORA and the SRK/T and Haigis formulas. The mean±standard deviation subjective residual astigmatism in non-toric IOL eyes (N=76) was 0.46± 0.39 D and showed a strong positive correlation with preoperative objective refractive astigmatism (r=0.2925, p=0.0109), intraoperative ORA–measured astigmatism (r=0.5555, p< 0.0001), postoperative objective refractive astigmatism (r=0.8188, p< 0.0001), and postoperative total corneal astigmatism (TCA) (r=0.4051, p=0.0003) and a negative correlation with preoperative anterior corneal astigmatism (r=− 0.3541, p=0.0017).Conclusion: ORA is a salient tool for improving the postoperative refractive accuracy of trifocal IOL power calculations and may help in determining the need for toric IOL use in astigmatic eyes with cataracts. Residual astigmatism correlated with objective refractive astigmatism, ORA-measured astigmatism, and postoperative TCA.Keywords: cataract surgery, intraoperative aberrometry, residual astigmatism, refractive prediction error, trifocal IOL

Seth M Pantanelli,1 Ashley Sun,1 Neal Kansara,2 Gerard Smits3 1Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, USA; 2Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA; 3Computer and Statistical Consultants Incorporated, Santa Barbara, CA, USACorrespondence: Seth M PantanelliDepartment of Ophthalmology, Penn State College of Medicine, 500 University Drive, HU19, Hershey, PA, 17033-0850, USA, Tel +1 717-531-5690, Fax +1 717-531-5009, Email spantanelli@pennstatehealth.psu.eduPurpose: The purpose of this study was to compare the Barrett (BTC) and Emmetropia Verifying Optical (EVO) Toric Calculators’ performance with regards to prediction of residual post-operative astigmatism after cataract surgery.Methods: This was a secondary analysis of de-identified data that was collected as part of a prospective multicenter clinical trial in which 109 eyes from 109 patients were implanted with a monofocal toric intraocular lens (IOL). Post-operative biometry was used to calculate the predicted post-operative residual astigmatism for each eye using the two different calculators. The vector difference between the actual and predicted residual astigmatism was calculated.Results: The mean absolute astigmatism prediction errors were 0.59 ± 0.38 D and 0.59 ± 0.36 D for the BTC and EVO calculators, respectively (p = 0.98). The centroid of the prediction errors were 0.18 D @ 89° ± 0.68 D and 0.20 D @ 89° ± 0.66 D, respectively (p = 0.21). The proportion of eyes in which the astigmatism prediction error was ≤ 0.5 D was 50% for BTC and 46% for EVO (p = 0.28). The proportion of eyes in which the post-operative astigmatism orientation was correctly predicted as being against-the-rule, with-the-rule, or oblique was 81% for BTC and 77% for EVO (p = 0.15).Conclusion: The Barrett and Emmetropia Verifying Optical Toric Calculators had similar performance with regards to their astigmatism prediction accuracy.Keywords: Barrett, EVO, astigmatism, toric, cataract, residual astigmatism

Visual rehabilitation after a keratoplasty is often compromised due to high amounts of residual astigmatism. Femtosecond laser-assisted astigmatic keratotomy (FLAK) is gaining popularity in decreasing this astigmatism. Though one set of two incisions suffices in most cases, sometimes the treatment proves insufficient and additional treatment is required. This case series evaluates the outcomes in patients who underwent two consecutive FLAK sets to correct post-keratoplasty residual astigmatism. All repeated FLAK cases performed on post-keratoplasty eyes were reviewed in a high-volume clinic as a non-comparative retrospective case series. The data extracted include the procedure parameters, time between procedures, refraction including sphere, astigmatism, spherical equivalent (SE), and uncorrected and best-spectacle-corrected distance visual acuity (UDVA, BSDVA, respectively). Eleven eyes of eleven patients aged 25.5 ± 10 treated with more than one FLAK procedure were identified. The average follow-up time was 6 months after the first FLAK and 24 ± 10 months after the second. The second FLAK was performed six months after the first. The preoperative mean astigmatism was −9.59 ± 2.36 D. At the final follow-up, the mean astigmatism decreased to −5.38 ± 1.79 D (p = 0.001). Repeated FLAK procedures achieved a significant and stable reduction of astigmatism in post-keratoplasty eyes. This procedure shows safety and effectivity in these complex eyes and may prevent the need for a further keratoplasty. [ABSTRACT FROM AUTHOR]

Purpose: To compare the accuracy in astigmatism reduction by using IOLM 700 steep total keratometry (TK) axis, Berdahl and Hardten astigmatism fix, and Barrett Rx formula following misaligned toric intraocular lens (IOL).Methods: Ten patients with residual refractive astigmatism due to misalignment following toric IOL implantation were included in this retrospective study. They were analyzed at days 4, 7/8, and 10/11 following primary cataract surgery on the platform of Berdahl and Hardten astigmatism fix, Barrett Rx formula, and IOLM 700 to determine the optimum axis of repositioning, and underwent IOL realignment on the steep TK axis of IOLM 700 assisted by the Callisto eye. The final outcome parameters were subjective refraction and orientation of toric IOL assessed 22 ± 1 days following repositioning surgery. These parameters were fed in the Barrett Rx formula and its vector analysis graph was utilized to determine the predicted ideal axis with the least residual astigmatism and the estimated residual astigmatism if the toric IOL was realigned according to the axis suggested by Berdahl and Hardten astigmatism fix and Barrett Rx formula.Results: Realigning the toric IOL on IOLM 700 steep TK axis along with the Callisto eye reduces the residual refractive astigmatism significantly (P = 0.003) from 2.00 ± 0.78 D to 0.18 ± 0.12 D (90.5 ± 7.6%) in comparison to the estimated 0.57 ± 0.31 D (68.4 ± 21.9%) by Berdahl and Hardten astigmatism fix and 0.61 ± 0.33 D (66.4 ± 23.5%) by Barrett Rx formula.Conclusion: Realigning the misaligned toric IOL on the IOLM 700 steep TK axis gives a better reduction in the residual refractive astigmatism in comparison to Berdahl and Hardten astigmatism fix and Barrett Rx formula. [ABSTRACT FROM AUTHOR]

AIM: To observe the clinical effect of Toric intraocular lens(Toric IOL)implantation in the correction of corneal astigmatism, and vector analysis of residual astigmatism and corneal astigmatism.METHODS: A retrospective case observation study. A total of 63 patients with 77 eyes who underwent phacoemulsification combined with Toric IOL implantation in our hospital from September 2018 to October 2019 were selected. LogMAR uncorrected distance visual acuity(UCDVA), best corrected distance visual acuity(BCDVA), residual astigmatism of subjective refraction were observed after operation in 1wk, 1mo, and 3mo. And after dilated pupil, the Toric IOL axis position was measured by OPD-scanⅢ, and compared with the target axis position(LAD).RESULTS: The median(interquartile range)of UCDVA at 1wk, 1mo, and 3mo after operation were 0.22(0.15, 0.40), 0.30(0.15,0.40),and 0.30(0.15, 0.40), which were better than those of UCDVA \〖0.82(0.60, 1.22)\〗 and BCDVA \〖0.52(0.30, 0.70)\〗 before operation(PPCONCLUSION: Toric IOL can effectively correct corneal astigmatism in patients with cataract and has good rotational stability. Astigmatism vector analysis can directly show the difference between predicting postoperative astigmatism and actual residual astigmatism, which is helpful to analyze and optimize the measurement of corneal astigmatism, calculation of IOL degree, surgical design, postoperative observation.

The purpose of this review is to evaluate the prediction of postoperative residual astigmatism and to determine the best prediction method for astigmatism correction. In recent findings for residual astigmatism in non-toric monofocal intraocular lens (IOL) implanted eyes, vector analysis can be used to correctly evaluate residual astigmatism by decomposing it. In predicting residual astigmatism, the with-the-rule (WTR) and against-the-rule (ATR) astigmatism components can now be almost predicted. This may be due to advances in inspection equipment and surgical technique. However, there are still issues with the oblique astigmatism component. In addition, corneal astigmatism is the most important predictor of postoperative residual astigmatism, and other predictors, such as refractive astigmatism, age, and lens thickness, have also been mentioned. However, all but corneal astigmatism are questionable because of the possibility of confounding variables. Total corneal astigmatism is more accurate in predicting residual astigmatism than anterior corneal astigmatism. Several predictions of residual astigmatism have been reported, but complete prediction has not been possible. Further research is needed, especially in predicting oblique astigmatism. However, I emphasize that the accuracy of predicting WTR and ATR astigmatism has improved considerably and can be predicted using regression equations with total corneal astigmatism.

Robert Edward AngDepartment of Cornea and Refractive Surgery, Asian Eye Institute, Makati City, PhilippinesPurpose: To compare the effect of induced astigmatic defocus on visual performance in pseudophakic eyes implanted with a small aperture, trifocal, or monofocal intraocular lens (IOL).Patients and methods: The study included 44 eyes with one of four types of IOL (IC-8 IOL (AcuFocus Inc., USA); FineVision (PhysIOL SA, Belgium); AT Lisa (Carl Zeiss AG, Germany); and enVista monofocal (Bausch & Lomb, USA). For astigmatic tolerance assessment, monocular distance visual acuity was measured with cylindrical lenses (power range=0.00–2.50 diopters (D) in 0.50 D increments) added to the subjects best-corrected distance manifest refraction. The assessment was repeated on three pre-determined axes (90°, 180°, and either 45° or 135°). The magnitude of astigmatic tolerance at each defocus step was assessed by taking the difference between logMAR visual acuity at the defocus step relative to that at 0.0 D (ie, no defocus condition).Results: Across all three axes, the reduction of mean monocular visual acuity at all defocus levels relative to no defocus was significantly smaller in IC-8 group compared to the other IOL groups. When the data was combined across all axes, the astigmatic tolerance of the IC-8 group was better than AT Lisa group from 0.50 D to 2.50 D and FineVision group from 0.50 D to 1.50 D (all P0.05, ANOVA). Among individual orientations, statistically significant differences were seen between IC-8 IOLs and the other IOLs, with the largest difference being in the oblique axis. Astigmatic tolerance at all axes combined was 1.40 D for IC-8 IOL, 0.70 D for AT Lisa and FineVision, and 1.00 D for enVista IOLs.Conclusion: The small aperture IC-8 IOL showed greater tolerance to induced astigmatic defocus compared to trifocal and monofocal IOLs.Keywords: cataract, refractive error, small aperture IOL, residual astigmatism

Purpose: To evaluate the effect of non-keratometric ocular astigmatisms on visual and refractive outcomes after photorefractive keratectomy (PRK) for correction of myopic astigmatisms. Methods: Seventy one eyes of 36 subjects were enrolled in this study. Patients underwent PRK for treatment of myopia. Subjects were evaluated for refractive error, keratometry, and visual acuity before and six months after surgery. Pre- and post-op non-keratometric astigmatisms were calculated by vectorial analysis of the difference between the corneal plane refractive astigmatism and keratometric astigmatism. Astigmatic analysis explored the contribution of non-keratometric astigmatisms. Results: The pre-op spherical equivalent (SE) was −6.27 ± 1.48 with 1.16 ± 1.02 diopters of corneal plane refractive astigmatism and 1.44 ± 0.47 diopters keratometric astigmatism. Post-op values were −0.60 ± 0.85, 0.56 ± 0.47, and 1.06 ± 0.57, respectively, 6 months after surgery. Pre- and post-op non-keratometric astigmatisms were 0.76 ± 0.41 and 0.76 ± 0.46, respectively, (P = 0.976) with significant correlation (r = 0.37, P = 0.002). Pre-op non-keratometric astigmatisms correlated to the pre-op SE (r = −0.25, P = 0.04). Pre-op non-keratometric astigmatisms had significant correlation with keratometric difference vector of astigmatic correction (r = 0.369, P = 0.002). Post-op non-keratometric astigmatisms correlated to keratometric induced astigmatism (r = 0.334, P = 0.006), keratometric index of success (r = 0.571, P

Purpose: To evaluate the correlation between refractive, corneal, and residual astigmatism and higher order aberrations (HOA) in refractive surgery candidates. Methods: Three hundred and seventy-five eyes of 188 patients aged 28.2 ± 6.24 years with a predominance of females (62.7%) were enrolled in this study. Refraction, topography (Orbscan IIz, Bausch & Lomb, Rochester, NY, USA), and aberrometry (Zywave, Bausch & Lomb, Rochester, NY, USA) were performed to determine refractive and corneal astigmatism and HOA for all participants. Ocular residual astigmatism was calculated using vector analysis. Results: The mean spherical equivalent was −3.59 ± 1.95 D and the mean refractive astigmatism was −1.97 ± 1.3 D. The mean HOA was 0.38 ± 0.15 μm in all cases, which increased with spherical equivalent (p

Introduction: Astigmatism reduces the postoperative visual performance after non-toric intraocular lenses (IOLs) implantation, and limits the use of refractive IOLs in cataract surgery. The purpose of this study was to compare the efficacy in astigmatism correction and the postoperative visual outcomes between the implantation of a trifocal IOL with femtosecond laser-assisted arcuate keratotomy (FSAK) in one eye and a bifocal toric IOL (TIOL) in the other, in patients with cataract and moderate astigmatism., Methods: This prospective observational paired-eye study enrolled patients with cataract and corneal astigmatism (CA) between 0.75 and 2.25 D in both eyes. The patients underwent a mix-and-match treatment comprising trifocal IOL implantation with FSAK and bifocal TIOL implantation. We compared the visual acuity (VA) at all distances, defocus curve, postoperative refractive astigmatism (RfA), CA, high-order aberrations, modulation transfer function (MTF) curve, and Strehl ratio between the two eye groups., Results: In total, 41 patients (82 eyes) were enrolled and completed a 6-month follow-up. The 1- and 3-month uncorrected distance VA and 3-month uncorrected near VA were greater in eyes with bifocal TIOLs than with trifocal IOLs and FSAK ( p  = 0.036, 0.010, and 0.030, respectively), whereas the latter had greater uncorrected intermediate VA at every visit and greater VA in the intermediate range of defocus curve (at -1.50 and - 2.00 D) than the eyes with bifocal TIOLs. The postoperative RA of the eyes with trifocal IOL and FSAK was significantly higher than that of the bifocal TIOL-implanted eyes at the 3- and 6-month follow-ups., Discussion: Both FSAK and TIOL implantation effectively reduce pre-existing moderate astigmatism in patients with cataract. The eyes with bifocal TIOLs had more stable long-term astigmatism correction, whereas those with trifocal IOLs and FSAK had better intermediate VA. Therefore, a mix-and-match implantation of trifocal IOL with FSAK and contralateral bifocal TIOL could achieve effective astigmatism correction and provide an overall optimal VA., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Shen, Hua, Zhang, Zhuo, Shen, Chen, Guo and Yang.)

Purpose To evaluate the correlation between refractive astigmatism ( RA) and anterior corneal astigmatism ( ACA), and determine the internal astigmatism ( IA) in 184 pseudophakic eyes. Methods The study was a prospective non-masked single-centre study. Patients were examined 8 weeks after phacoemulsification with implantation of aspheric one-piece monofocal IOLs. Examination included autokeratometry and subjective refraction. All refractive data were converted to the corneal plane. The corneal refractive index, taken to be 1.376, was used to estimate the ACA. All astigmatisms were converted to net curvital and net torsional powers with the steeper corneal plane as the reference meridian. Curvital power is the force acting along a given meridian, and torsion is the power twisting the astigmatic direction out of that plane. The internal astigmatism ( IA) was calculated as the difference between RA and ACA. Results For curvital powers, the refractive astigmatism ( KP(Φ) RA) could be described as a function of anterior corneal astigmatic magnitude ( KP(Φ) ACA) and direction α by the multiple linear regression equation: KP(Φ) RA = −0.09 + 0.61* KP(Φ) ACA + 0.33*cos2α, ( r2 = 0.59, p < 0.0001). The average internal astigmatism amounted to 0.47 D inclined 92° relative to the steeper anterior corneal meridian. The magnitude of internal astigmatism depended on the angle α of the steeper anterior corneal meridian, averaging 0.86 D at 91° for with-the-rule, 0.37 D at 95° for oblique and 0.17 D at 97° for against-the-rule corneal astigmatisms. Conclusions The internal astigmatism varies as a function of the direction of the anterior steeper corneal meridian. In patient candidates to surgical correction of astigmatism, measuring only the curvature of the anterior corneal surface and neglecting that of the posterior corneal surface can lead to inaccurate evaluation of total corneal astigmatism. [ABSTRACT FROM AUTHOR]

The purpose of this review is to evaluate the prediction of postoperative residual astigmatism and to determine the best prediction method for astigmatism correction. In recent findings for residual astigmatism in non-toric monofocal intraocular lens (IOL) implanted eyes, vector analysis can be used to correctly evaluate residual astigmatism by decomposing it. In predicting residual astigmatism, the with-the-rule (WTR) and against-the-rule (ATR) astigmatism components can now be almost predicted. This may be due to advances in inspection equipment and surgical technique. However, there are still issues with the oblique astigmatism component. In addition, corneal astigmatism is the most important predictor of postoperative residual astigmatism, and other predictors, such as refractive astigmatism, age, and lens thickness, have also been mentioned. However, all but corneal astigmatism are questionable because of the possibility of confounding variables. Total corneal astigmatism is more accurate in predicting residual astigmatism than anterior corneal astigmatism. Several predictions of residual astigmatism have been reported, but complete prediction has not been possible. Further research is needed, especially in predicting oblique astigmatism. However, I emphasize that the accuracy of predicting WTR and ATR astigmatism has improved considerably and can be predicted using regression equations with total corneal astigmatism.

Purpose: To determine the distribution of residual and corneal astigmatism (CA) in children aged 6-18 years and their relationship with age, sex, spherical equivalent, and biometric parameters., Methods: In this cross-sectional study, multi-stage stratified cluster sampling was done to select students from Dezful, a city in Southwestern Iran. Examinations included the measurement of visual acuity with and without optical correction, refraction with and without cycloplegia, and biometry using the Biograph (Lenstar, Germany). The main outcomes in this report were corneal and residual astigmatism. The CA was measured by Biograph (difference between k1 and k2), and residual astigmatism was calculated using Alpine method. The power vector method was applied to analyze the data of astigmatism., Results: Of 864 students that were selected, 683 (79.1%) participated in the study. The mean residual and CA were -0.84 diopter (D) and -0.85 D, respectively. According to the results of J0 and J45 vectors, residual astigmatism was -0.33 D and 0.04 D, and CA was 0.38 D and 0.01 D, respectively. With-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism were seen in 3.4%, 66.8%, and 4.5% of the children with residual astigmatism and 67.94%, 1.3%, and 1.5% of the children with CA. Residual astigmatism decreased with an increase in spherical refractive error, whereas CA increased with an increase in spherical refractive error., Conclusion: The results of the present study showed a high prevalence and amount of residual astigmatism with ATR pattern among the 6-18-year-old population and the compensatory effect of this type of astigmatism on CA that mostly followed a WTR pattern., Competing Interests: There are no conflicts of interest., (Copyright: © 2020 Journal of Current Ophthalmology.)

Purpose: To evaluate the effect of non-keratometric ocular astigmatisms on visual and refractive outcomes after photorefractive keratectomy (PRK) for correction of myopic astigmatisms., Methods: Seventy one eyes of 36 subjects were enrolled in this study. Patients underwent PRK for treatment of myopia. Subjects were evaluated for refractive error, keratometry, and visual acuity before and six months after surgery. Pre- and post-op non-keratometric astigmatisms were calculated by vectorial analysis of the difference between the corneal plane refractive astigmatism and keratometric astigmatism. Astigmatic analysis explored the contribution of non-keratometric astigmatisms., Results: The pre-op spherical equivalent (SE) was -6.27 ± 1.48 with 1.16 ± 1.02 diopters of corneal plane refractive astigmatism and 1.44 ± 0.47 diopters keratometric astigmatism. Post-op values were -0.60 ± 0.85, 0.56 ± 0.47, and 1.06 ± 0.57, respectively, 6 months after surgery. Pre- and post-op non-keratometric astigmatisms were 0.76 ± 0.41 and 0.76 ± 0.46, respectively, ( P  = 0.976) with significant correlation (r = 0.37, P  = 0.002). Pre-op non-keratometric astigmatisms correlated to the pre-op SE (r = -0.25, P  = 0.04). Pre-op non-keratometric astigmatisms had significant correlation with keratometric difference vector of astigmatic correction (r = 0.369, P  = 0.002). Post-op non-keratometric astigmatisms correlated to keratometric induced astigmatism (r = 0.334, P  = 0.006), keratometric index of success (r = 0.571, P  < 0.001), and post-op keratometric astigmatism (r = 0.736, P  < 0.001)., Conclusions: Higher or lower non-keratometric ocular astigmatisms did not have any effect on refractive and visual outcome after PRK. PRK effectively corrected total refractive astigmatism through correction of keratometric astigmatism and additional adjustment to compensate for non-keratometric ocular astigmatisms.

Purpose: To evaluate the correlation between refractive, corneal, and residual astigmatism and higher order aberrations (HOA) in refractive surgery candidates., Methods: Three hundred and seventy-five eyes of 188 patients aged 28.2 ± 6.24 years with a predominance of females (62.7%) were enrolled in this study. Refraction, topography (Orbscan IIz, Bausch & Lomb, Rochester, NY, USA), and aberrometry (Zywave, Bausch & Lomb, Rochester, NY, USA) were performed to determine refractive and corneal astigmatism and HOA for all participants. Ocular residual astigmatism was calculated using vector analysis., Results: The mean spherical equivalent was -3.59 ± 1.95 D and the mean refractive astigmatism was -1.97 ± 1.3 D. The mean HOA was 0.38 ± 0.15 μm in all cases, which increased with spherical equivalent (p < 0.05). There was a positive significant correlation between both corneal and refractive astigmatism and HOA (p < 0.05), but there was no significant correlation between residual astigmatism and HOA (p = 0.122)., Conclusion: The results of the study showed significant correlations between corneal and refractive astigmatisms and HOA.