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.

Compensatory Interactions between Corneal and Internal Astigmatism despite Lifestyle Changes.

This study explores whether children's refractive errors and visual behaviors reverted to pre-COVID-19 levels a year after normal schooling resumed in Hong Kong as well as the impact of corneal and internal astigmatism on refractive astigmatism development. Vision survey data and questionnaire results collected in 2022 (n = 119) and 2020 (n = 173) were compared. Cross-sectional data showed similar proportions of astigmatism (cylindrical power ≥ 0.75 D) in the 2020 (49.1%) and 2022 cohorts (55.5%). Despite a 0.28 D increase in corneal astigmatism, a compensatory 0.24 D increase in internal astigmatism of opposite direction kept refractive astigmatism relatively stable. The questionnaire data showed that children spent an additional 0.5 h/day outdoors on weekends post-resumption of normal schooling but engaged in more near-work activities, especially non-screen near-work, by approximately 1 h/day on both weekdays and weekends. These findings were supported by longitudinal data from 72 children who participated in both surveys. This study highlights the significant role of corneal and internal astigmatism in refractive astigmatism changes. Despite the return to in-person classes, children's total near-work time increased and astigmatism remained high. These findings underscore the need for comprehensive strategies to reduce the high environmental risks for refractive error development in children.

Differences in refractive astigmatism, anterior corneal surface astigmatism and ocular residual astigmatism between dominant and non-dominant eyes in myopia / 中华实验眼科杂志

Objective:To investigate the differences in refractive astigmatism, the anterior corneal surface astigmatism and ocular residual astigmatism between dominant and non-dominant eyes in myopia.Methods:A corss-sectional study was conducted.Two hundred and seventy-six eyes from 138 patients with myopia who were to receive corneal refractive surgery in the Refractive Surgery Center of Tianjin Eye Hospital from January to March 2018 were included.Ocular dominance was assessed with the hole-in-the-card test.The manifest refraction and corneal topography were performed in order to measure the sphericity, spherical equivalent, the astigmatism of anterior corneal surface and total cornea.Vector analysis was used to calculate the value of the ocular residual astigmatism and the components of astigmatism, including J0 and J45 of both the refractive astigmatism and the astigmatism of anterior corneal surface.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Tianjin Eye Hospital (No.201909).Results:It was found that 61.6%(85/138) of the subjects was right-eye dominant.There was no significant difference in sphericity and spherical equivalent, J0 and J45 of the refractive astigmatism and the astigmatism of anterior corneal surface between dominant and non-dominant eyes (all at P>0.05). The magnitude of the ocular residual astigmatism of the dominant eye was 0.607(0.451, 0.808)D, which was lower than 0.701(0.497, 0.901)D of the non-dominant eye, showing a statistically significant difference ( Z=-2.52, P=0.01). Conclusions:In the myopic population with no significant difference in the sphericity and spherical equivalent between the dominant and non-dominant eyes, the magnitude of the ocular residual astigmatism of the dominant eye is significantly lower than that of the non-dominant eye, which may play an important role in the ocular dominance formation.

Evaluation of Ocular Residual Astigmatism in Eyes with Myopia and Myopic Astigmatism and Its Interaction with Other Forms of Astigmatism.

Purpose: To evaluate the prevalence, magnitude, and direction of ocular residual astigmatism (ORA) in eyes with myopia and myopic astigmatism, and its interaction with refractive, anterior corneal, posterior corneal, and true net power astigmatism. Patients and Methods: Refractive surgery candidates with myopia and myopic astigmatism were studied. Refractive astigmatism (RA) was measured using the Nidek® AR-310A autorefractometer. Anterior corneal astigmatism (ACA), posterior corneal astigmatism (PCA), and true net power astigmatism (TNP) were measured using the Wavelight® Oculyzer II. Astigmatism was converted from polar to vector notation. ORA was calculated by vector subtraction of ACA from RA vertexed to corneal plane. Compensation factor (CF) was calculated as the ratio of ORA that compensates ACA for both J0 and J45. Results: 154 eyes of 88 patients (mean age 31.7±7.1 years) were included. With-the-rule (WTR) astigmatism was the most common for both RA (55.6%) and ACA (74%), while against-the-rule (ATR) was the most common for PCA (87.7%) and ORA (74.0%). The axes of RA and ACA were within 10° of each other in 46.8% of the eyes, and within 30° of each other in 76.0%. The mean difference in value between the axis of RA and ACA was 25.6°. 71.4% of eyes in the study had an ORA ≥ 0.5D, 44.1% had ORA ≥ 0.75D and 26% had ORA ≥ 1D. There was a statistically significant difference between ACA and each of RA and TNP. Using TNP to calculate ORA instead of ACA reduced its magnitude. RA is positively correlated to ACA and more strongly to TNP. The most common pattern of compensation between ORA and ACA was under-compensation for J0 (49%) and same-axis-augmentation for J45 (35%). Conclusion: ORA, PCA, and the interaction between ORA and ACA can affect results during refractive planning.

Predicting Residual Astigmatism in Cataract Surgery.

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.

Magnitude of astigmatism - A comparison between eyes.

PURPOSE: Astigmatism is a highly prevalent refractive error and while studies typically focus to describe the axis symmetry between eyes, little is known about the refractive symmetry. Therefore, this study determined the astigmatic power symmetry between eyes in a large clinic population. METHODS: A clinical chart review was conducted at three optometric practices in the United States, the United Kingdom and Canada and subjective refraction data from 88,891 patients 14-70 years of age who presented with at least -0.25DC refractive astigmatism in at least one eye were included in the analysis. Data were obtained at these practices between January 2014 and March 2017. The overall distribution (%) and magnitude (DC) of astigmatism was determined and refractive differences between eyes were identified. RESULTS: The mean age of the patients was 42.1 ± 15.9 years and included 51,685 (58%) female and 37,206 (42%) male patients. In this data pool of 177,782 eyes, 10.9% required zero astigmatic correction, while 56.2% had astigmatism of -0.25 to -0.75DC. In total 23.9% of patients presented with astigmatism of at least -0.75DC in only one eye, while the other eye had 0 to -0.50DC. Overall, the difference in astigmatism between eyes was less than -0.75DC for 82.1% of astigmatic patients. For patients who presented with astigmatism of -1.00DC in the right eye, 80.8% of them had an astigmatic prescription of -1.00 ± 0.50DC in the left eye. For an astigmatic prescription of -4.00DC in the right eye, only 40.6% of patients exhibited astigmatism of -4.00DC ± 0.50DC in the left eye. CONCLUSIONS: The majority of patients exhibited a difference in astigmatism between eyes of less than -0.75DC, however the refractive cylinder power symmetry was significantly lower in patients with higher refractive astigmatism.

Prediction of postoperative refractive astigmatism before toric intraocular lens implantation.

BACKGROUND: To determine the preoperative factors influencing refractive astigmatism after cataract surgery for astigmatism correction by toric intraocular lens (IOL) implantation and to evaluate the prediction model using these factors. METHODS: Prospective, observational case series. The right eyes of forty consecutive patients with preoperative corneal astigmatism of the total cornea of 1.5 diopters (D) or more in magnitude and scheduled for implantation of a non-toric IOL during cataract surgery with a 2.4-mm temporal clear corneal incision were examined prospectively. The vertical/horizontal astigmatism component (J0) and oblique astigmatism component (J45) of refractive and corneal astigmatism were converted using power vector analysis. Multivariate regression analysis was performed with refractive astigmatism at three months postoperatively as the dependent variable, and preoperative parameters including age, sex, refractive astigmatism, corneal astigmatism, sphere, spherical equivalent, intraocular pressure, corneal thickness, anterior chamber depth, lens thickness, lens positions (tilt and decentration), axial length, and corneal higher order aberrations as independent variables. The root mean square (RMS) errors were calculated to express the regression model fit. RESULTS: The regression model for the J0 component was [Formula: see text] (R2 = 0.96, P < 0.001). The model for the J45 component was [Formula: see text] (R2 = 0.72, P < 0.001). The mean RMS errors for preoperative corneal astigmatism alone and the multivariate model were 0.58 D and 0.46 D, respectively. There was a statistically significant difference between them (P = 0.02). CONCLUSIONS: Refractive astigmatism after implantation of a toric IOL can be predicted by the regression model more accurately than by corneal astigmatism alone. However, the prediction of oblique astigmatism remains a challenge.

Transitional conic toric intraocular lens for the management of corneal astigmatism in cataract surgery.

SYNOPSIS: Transitional toric intraocular lens (IOL) was developed to improve refractive outcomes in cataract surgery. We report refractive, vectorial outcomes, and stability of spherical equivalent over 12 months after implantation of this IOL. PURPOSE: To evaluate visual and refractive outcomes of a transitional conic toric intraocular lens (IOL) (Precizon®) for the correction of corneal astigmatism in patients undergoing cataract surgery. SETTING: The Ocular Microsurgery Institute (IMO), a private practice in Barcelona, Spain. DESIGN: This is a retrospective, non-randomized study. METHODS: Retrospective chart review of 156 patients with preoperative regular corneal astigmatism >0.75 diopters (D) who underwent consecutive phacoemulsification and Precizon toric IOL implantation between January 2014 and December 2015 was performed. Two groups were divided according to attempted residual refraction: group 1 with emmetropia and group 2 with mild myopia for monovision. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest refraction were analyzed preoperatively and 3, 6, and 12 months postoperatively. RESULTS: Precizon toric IOL was implanted in 97 eyes of 61 patients. Six months postoperatively, none of the eyes lost any line of CDVA. In all, 98% of the eyes were within ±1.00 D of attempted spherical correction. The mean preoperative keratometric cylinder was 1.92 ± 1.04 D (range 0.75-6.78), and the mean postoperative refractive cylinder was 0.77 ± 0.50 D (range 0-2.25), with 81% of the eyes with ≤1.00 D of residual cylinder. Two IOLs required realignment due to intra-operative positioning error. Eleven eyes required enhancement with corneal refractive surgery. CONCLUSION: Preexisting regular corneal astigmatism was effectively and safely corrected by the implantation of the transitional conic toric IOL in patients undergoing cataract surgery.

Efficacy of transepithelial corneal collagen crosslinking for keratoconus: 12-month follow-up.

PURPOSE: To evaluate the efficacy of transepithelial corneal collagen crosslinking (TE-CXL) in patients with progressive keratoconus. PATIENTS AND METHODS: This is a prospective interventional consecutive study carried out on 30 eyes of 18 patients with progressive keratoconus who underwent TE-CLX using both ParaCel™ (riboflavin 0.25%, hydroxy propyl methyl cellulose, NaCl, ethylenediaminetetraacetic acid [EDTA], Tris, and benzalkonium chloride) and vibeX-Xtra (riboflavin 0.22%, phosphate-buffered saline solution). The procedure was carried out at Ebsar Eye Center in Egypt in the period from 2012 to 2014. The follow-up visits were scheduled on days 1, 3, 6, and 12 months after treatment. RESULTS: There were statistically significant improvements (P<0.001) in the mean best-corrected visual acuity (0.54±0.22 preoperatively vs 0.61±0.19 at 12 months postoperatively), the mean manifest refraction spherical equivalent (MRSE; -6.16±3.90 diopters [D] preoperatively and -5.91±3.72 D at 12 months postoperatively), and the mean preoperative corneal astigmatism (-3.39±2.11 D preoperatively and -2.46±2.60 D at 12 months postoperatively). CONCLUSION: TE-CXL could halt the progression of keratoconus in adult patients. TE-CXL resulted in a statistically significant improvement in best-corrected visual acuity, manifest refraction, refractive and corneal astigmatism and K values in keratoconus patients at the 12-month follow-up. Larger sample sizes and longer follow-ups are required in order to make meaningful conclusions.

Correlation of higher order aberrations and components of astigmatism in myopic refractive surgery candidates.

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.

Correlation of major components of ocular astigmatism in myopic patients.

PURPOSE: To investigate the correlation of major components of ocular astigmatism in myopic patients in an academic hospital. METHODS: This cross-sectional study was conducted on 376 eyes of 188 patients who were referred to Farabi Eye Hospital for refractive surgery. Preoperative examinations including refraction and corneal topography were performed for all candidates to measure refractive and corneal astigmatism. Ocular residual astigmatism was calculated using vector analysis. Pearson's correlation and ANOVA analysis were used to evaluate the strength of the association between different types of astigmatism. Both eyes were defined as cluster and the Generalized Estimating Equations (GEE) analysis were performed. RESULTS: Mean age of 119 women (63.3%) and 69 men (36.7%) was 27.8 ± 5.7 years. Mean refractive error based on spherical equivalent was -3.59 ± 1.95D (range, -0.54 to -10.22D). Mean refractive and corneal astigmatism was 1.97 ± 1.3D and 1.85 ± 1.01D, respectively. Mean amount of ORA was 0.65 ± 0.36D.There was a significant correlation between ORA and refractive astigmatism(r=0.23, p<0.001), corneal and refractive astigmatism (r=0.91, p<0.001) and a weak correlation between ORA and corneal astigmatism (r=0.13, p=0.014). There was a significant correlation between J0 and J45 values of ORA and corneal astigmatism (p<0.001). CONCLUSION: There is a significant correlation between ORA and refractive astigmatism, refractive and corneal astigmatism and a weak correlation between ORA and corneal astigmatism in refractive surgery candidates. Identifying the type of astigmatism and preoperative measurement of ocular residual astigmatism is highly recommended prior to any refractive surgery, especially in cases with significant astigmatism.

Resultados del cálculo del poder del lente intraocular mediante la fórmula de Haigis / Results of the intraocular lens power calculation through Haigis´ formula

OBJETIVO: Determinar la efectividad de la fórmula de Haigis en el cálculo del poder dióptrico del lente intraocular. MÉTODOS: Se realizó un estudio descriptivo prospectivo, de pacientes operados de catarata mediante la técnica de Facoemulsificación en el Servicio de Microcirugía del Instituto Cubano de Oftalmología Ramón Pando Ferrer entre enero 2007 a enero 2008. Para el cálculo del poder del lente intraocular se empleó el IOL Máster y la fórmula de Haigis. La muestra de 101 pacientes, se seleccionó por el método aleatorio simple, de los cuales 28 fueron intervenidos en ambos ojos, para un total de 129 ojos. RESULTADOS: El equivalente esférico preoperatorio y posoperatorio no tuvieron diferencias, sí existieron entre esfera esperada y la obtenida. La mayor diferencia entre la esfera esperada y la obtenida fue encontrada en los pacientes hipermétropes. El astigmatismo refractivo fue bajo. La longitud axil posoperatoria no se modificó y la mejor agudeza visual sin corrección y con corrección mejoró en más de cuatro líneas en la cartilla de Snellen CONCLUSIÓN: Se demostró la efectividad de la fórmula de Haigis en el cálculo del poder del lente intraocular(AU)

OBJECTIVE: To determine the effectiveness of Haigis´formula in the intraocular lens power calculation. METHODS: A prospective and descriptive study was conducted in patients operated from cataract with phacoemulsification technique at the Microsurgery Service of Ramón Pando Ferrer Cuban Institute of Opththalmology from January 2007 to January 2008. The IOL Master and the Haigis´formula were used for the intraocular lens power calculation. The sample of 101 patients was selected by the simple random method, of whom 28 underwent surgery in both eyes, for a total number of 129 eyes. RESULTS: The Pre- and the post-operative spherical equivalents did not have any differences; but the expected sphere and the real sphere did show differences. The biggest difference between the expected sphere and the real one was found in the hypermetropic patients. The refractive astigmatism was low. The postoperative axil length did not change and the best visual acuity without/ with Correction improved by more than four lines in the Snellen´s chart. CONCLUSION: The effectiveness of Haigis´ formula was confirmed in the intraocular lens power calculation(AU)

Resultados del cálculo del poder del lente intraocular mediante la fórmula de Haigis / Results of the intraocular lens power calculation through Haigis´ formula

OBJETIVO: Determinar la efectividad de la fórmula de Haigis en el cálculo del poder dióptrico del lente intraocular. MÉTODOS: Se realizó un estudio descriptivo prospectivo, de pacientes operados de catarata mediante la técnica de Facoemulsificación en el Servicio de Microcirugía del Instituto Cubano de Oftalmología Ramón Pando Ferrer entre enero 2007 a enero 2008. Para el cálculo del poder del lente intraocular se empleó el IOL Máster y la fórmula de Haigis. La muestra de 101 pacientes, se seleccionó por el método aleatorio simple, de los cuales 28 fueron intervenidos en ambos ojos, para un total de 129 ojos. RESULTADOS: El equivalente esférico preoperatorio y posoperatorio no tuvieron diferencias, sí existieron entre esfera esperada y la obtenida. La mayor diferencia entre la esfera esperada y la obtenida fue encontrada en los pacientes hipermétropes. El astigmatismo refractivo fue bajo. La longitud axil posoperatoria no se modificó y la mejor agudeza visual sin corrección y con corrección mejoró en más de cuatro líneas en la cartilla de Snellen CONCLUSIÓN: Se demostró la efectividad de la fórmula de Haigis en el cálculo del poder del lente intraocular

OBJECTIVE: To determine the effectiveness of Haigis´formula in the intraocular lens power calculation. METHODS: A prospective and descriptive study was conducted in patients operated from cataract with phacoemulsification technique at the Microsurgery Service of Ramón Pando Ferrer Cuban Institute of Opththalmology from January 2007 to January 2008. The IOL Master and the Haigis´formula were used for the intraocular lens power calculation. The sample of 101 patients was selected by the simple random method, of whom 28 underwent surgery in both eyes, for a total number of 129 eyes. RESULTS: The Pre- and the post-operative spherical equivalents did not have any differences; but the expected sphere and the real sphere did show differences. The biggest difference between the expected sphere and the real one was found in the hypermetropic patients. The refractive astigmatism was low. The postoperative axil length did not change and the best visual acuity without/ with Correction improved by more than four lines in the Snellen´s chart. CONCLUSION: The effectiveness of Haigis´ formula was confirmed in the intraocular lens power calculation

Pseudophakic Residual Astigmatism

We investigated pseudophakic residual astigmatism in order to minimize postoperative refractive astigmatism. We examined 110 eyes of 87 patients who had undergone phacoemulsification with small incision and posterior chamber intraocular lens (IOL) implantation. Corneal astigmatism was measured using an autokeratometer (RK-5, canon), refractive astigmatism by manifest refraction, and residual astigmatism by vector analysis. Mean pseudophakic residual astigmatism was +0.47 X 176degrees, predominantly against-the-rule. Variations of pseudophakic residual astigmatism according to sex, age and IOL type were not statistically significant. When performing cataract surgery as refractive surgery, we may consider that pseudophakic residual astigmatism is approximately 0.50D against-the-rule.