Against-the-rule Astigmatism Research Articles

Astigmatism in Duane Retraction Syndrome

PurposeTo compare the prevalence, magnitude, and type of astigmatism among patients with different Duane Retraction Syndrome (DRS) types.MethodThis retrospective cross-sectional study reviewed the records of 312 DRS patients. Patients were categorized into DRS Types 1, 2, 3, and bilateral cases. Refractive errors and visual acuity were analyzed, emphasizing the prevalence of astigmatism types, specifically with-the-rule (WTR), against-the-rule (ATR), and oblique, as well as the power vectors for each DRS subtype.ResultsOur study included 312 patients with DRS, comprising 44.6% males and a median age of 18.5 years (interquartile range [IQR]: 7–27). Of these, 280 had unilateral DRS and 32 had bilateral DRS. The median age for unilateral DRS patients was 19 years (IQR: 7–27; 43.2% males), whereas for bilateral DRS patients, it was 16 years (IQR: 6-29.2; 56.3% males). In all DRS patients, 180 (57.7%) were diagnosed with Type 1 DRS, 87 (27.9%) with Type 2 DRS, and 45 (14.4%) with Type 3 DRS. In unilateral cases, WTR astigmatism was the most prevalent (56.8%), followed by oblique (23.6%) and ATR astigmatism (19.6%). Bilateral DRS patients exhibited a similar distribution in both eyes, with WTR astigmatism also being predominant. The comparative analysis of power vectors indicated that Type 1 DRS exhibited a greater prevalence of WTR and oblique astigmatism, whereas ATR astigmatism was the predominant pattern in Types 2 and 3. A comparison of cylindrical powers and power vectors among fellow eyes of different DRS subtypes revealed that Type 2 DRS had significantly higher cylindrical power (p = 0.017) and a greater tendency toward ATR astigmatism (p = 0.038) than fellow eyes in other subtypes, suggesting that astigmatic changes may also occur in fellow eyes.ConclusionOur study demonstrates a high prevalence of astigmatism, particularly WTR astigmatism, in DRS patients. Furthermore, we found significant associations between specific astigmatism patterns and DRS subtypes, suggesting a potential link between extraocular muscle innervation, co-contraction, and corneal shape. These findings highlight the importance of comprehensive astigmatism assessment in DRS patients for optimal refractive management.

Correction of low to moderate corneal astigmatism by steep-axis incision in image-guided cataract surgery

Objective: To explore the corrective effect of cataract extraction surgery combined with a 2.8 mm steep-axis corneal incision under ophthalmic surgical navigation on low-to-moderate corneal astigmatism and different types of corneal astigmatism. Methods: A prospective cohort study was conducted. Patients with age-related cataract who underwent cataract extraction combined with single-focus intraocular lens implantation in the Department of Ophthalmology at the Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from June to October 2023 and had a total corneal regular astigmatism degree of ≥0.50 D and <1.50 D were continuously collected. Patients were divided into a low-degree group (<1.00 D) and a moderate-degree group (≥1.00 D) according to corneal astigmatism degree. Simultaneously, they were classified into with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism based on preoperative corneal astigmatism axis position. Subjective refraction and anterior segment biometer examination were performed before and 3 months after surgery, respectively. Vector analysis of corneal astigmatism was conducted using the Alpins vector analysis method. The main observational indicators included target induced astigmatism, surgically induced astigmatism, and the correction index. Results: A total of 95 patients (110 eyes) were collected in this study. Thirteen patients (18 eyes) were lost to follow-up, and finally 82 patients (92 eyes) were included. In the low-degree group, there were 14 males (16 eyes) and 26 females (23 eyes), with an age of (69.62±12.22) years. In the moderate-degree group, there were 13 males (15 eyes) and 33 females (35 eyes), with an age of (72.98±8.28) years. The target astigmatism correction amount, surgically induced astigmatism, and deviation vector in the low-degree group were all smaller than those in the moderate-degree group (all P<0.05). Postoperative corneal astigmatism in both groups was undercorrected. The correction index in the low-degree group (0.88±0.44) was greater than that in the moderate-degree group (0.59±0.34) (P=0.001), and the undercorrection proportion in the moderate-degree group (90.00%, 45/50) was much higher than that in the low-degree group (57.14%, 24/42). In the low-degree group, the correction index from high to low was WTR (1.07±0.41), oblique (0.90±0.58), and ATR astigmatism eyes (0.69±0.37). After multiple comparison analysis, the correction index of WTR astigmatism eyes was significantly higher than that of ATR astigmatism eyes (P<0.05). The success index from high to low was oblique (0.82±0.57), ATR (0.74±0.39), and WTR astigmatism eyes (0.68±0.43). In the moderate-degree group, the order of the correction index from high to low was the same as that in the low-degree group, also WTR (0.79±0.33), oblique (0.71±0.50), and ATR astigmatism eyes (0.53±0.30), but there was no statistical significance among the three (P>0.05). In the low-degree group, there were 6 WTR astigmatism eyes undercorrected, fewer than 12 overcorrected eyes; there were 16 ATR astigmatism eyes undercorrected, more than 3 overcorrected eyes. In the moderate-degree group, there were 6 WTR astigmatism eyes undercorrected, more than 2 overcorrected eyes, but there were 2 ATR astigmatism eyes overcorrected, fewer than 34 undercorrected eyes. Conclusions: Cataract extraction surgery combined with a steep-axis corneal incision can achieve a certain astigmatism correction effect in patients with preoperative low-to-moderate corneal astigmatism. Patients with a preoperative corneal astigmatism degree of mild can achieve a better astigmatism correction effect than those with moderate, especially in the WTR astigmatism population. However, for cataract patients with preoperative corneal astigmatism of moderate and WTR astigmatism, a steep-axis corneal incision can also be combined to correct astigmatism as it can achieve the expected postoperative "with-the-rule undercorrection".

EFFECT OF SUPEROTEMPORAL CLEAR CORNEAL INCISION ON PRE EXISTING ASTIGMATISM AFTER PHACOEMUSIFICATION SURGERY

Background: Historically, patients undergoing cataract surgery were at an increased risk of developing surgically induced astigmatism with the advent of modern methods of cataract surgery, the focus shifted towards smaller sized incisions and minimally invasive surgery. Smaller incision produces less post-operative change in astigmatism and early visual rehabilitation as compared to larger incisions. This study was conducted to evaluate and compare the difference between pre and post op corneal astigmatism among patients undergoing phacoemulsification surgery, for cataract, via a superotemporal clear corneal incision. Methods: This was a longitudinal study that enrolled 85 patients between the ages of 40 and 90 years at Ophthalmology Department, Jinnah International Hospital, Abbottabad. Patients were divided into 2 groups according to their pre exiting astigmatism. Group A, With the Rule (WTR), astigmatism and Group B, Against the Rule (ATR) astigmatism. Astigmatism was measured and compared pre operatively, and on day 1, day 7 and day 30 post operatively via auto kerato-refractometer. Results: The mean astigmatism in patients in Group A (WTR astigmatism) preoperatively was 0.76 Diopters, whereas patients in Group B (ATR astigmatism) had a mean pre operative astigmatism of 0.68 Diopters. Mean astigmatism post operatively at day 30 was 0.86 Diopters for Group A, and 1.02 Diopters for Group B. Only 2 out of 36 patients in Group A had a shift to ATR astigmatism, whereas 4 out of 49 patients in Group B had a shift to WTR astigmatism by post op day 30. Conclusion: Superotemporal clear corneal incision is a relatively stable and effective site for incision during phacoemulsification surgery, and causes negligible change in pre operative astigmatism.

Analysis of surgically induced astigmatism of the anterior, posterior, and total cornea after implantable collamer lens implantation: a comparative study between temporal and superior clear corneal incisions

BackgroundTo comparatively analyze the surgically induced astigmatism (SIA) of the anterior, posterior, and total corneas of eyes undertaking implantable collamer lens (ICL) implantation with temporal or superior corneal incisions.MethodsOne hundred and nine eyes of 109 patients who received ICL implantation were recruited: 40 eyes had temporal incisions and 69 eyes had superior incisions. Total corneal refractive power (TCRP); simulated keratometry of the anterior (Sim-KAnt) and posterior (Sim-KPost) corneal curvature; and astigmatism of the anterior (CAAnt), posterior (CAPost), and total (CATCRP) cornea were recorded through a Pentacam preoperatively and 3 months postoperatively. The SIA of the anterior, posterior, and total cornea were also compared between the two groups.ResultsThere were no significant intergroup differences for TCRP, Sim-KAnt, Sim-KPost, CAAnt, CAPost, or CATCRP, preoperatively. However, values of CAAnt, CAPost, and CATCRP with temporal incision were significantly higher than those parameters with superior incision postoperatively. All of the SIA of the anterior, posterior, and total cornea were significantly lower for temporal incision than those with a superior incision (p < 0.001, p = 0.006 and p = 0.001 respectively). Meanwhile, the superior incisions created against-the-rule (ATR) astigmatism, and temporal incisions always induce with-the-rule (WTR) astigmatism in total cornea.ConclusionsA superior incision may be suitable for correcting WTR astigmatism, while a temporal incision for correcting ATR astigmatism when using a non-toric ICL. Meanwhile, temporal incision could be a better choice with little preoperative astigmatism or that preoperative astigmatism would be corrected with toric ICLs.Trial registrationRegistration number: ChiCTR2100051739. Prospectively registered: 01 October 2021.

Comparative Analysis of Tolerance to Experimentally Induced Astigmatism with Three Types of Multifocal Intraocular Lenses.

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. 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. 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. 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.

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.]

Comparison of the Clinical Effectiveness of Correcting Different Types of Astigmatism with Small Incision Lenticule Extraction.

Few studies have reported the differential outcomes of Small Incision Lenticule Extraction (SMILE) on myopic astigmatism. Given this, we examined the effectiveness of SMILE for up to one year, comparing with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism, conducting a retrospective review of patients who underwent correction of myopic astigmatism using the 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec) at two refractive clinics in Poland between 2016-2017. Patients were aged ≥21 with stable refractive errors between -0.5 and -10.0 diopter (D) with astigmatism up to 5D. The mean age of the 209 patients (355 eyes) available was 32 years; 58.4% were female. Of these, 247 had WTR, 62 oblique, and 46 ATR astigmatism. The mean pre-operative spherical equivalent (SE) was -5.4 ± 2.57D and the cylinder -1.7 ± 1.0D. The mean SE for WTR reduced from -5.60 ± 2.37D to -0.31 ± 0.67D at 2 months and -0.38 ± 0.70D at 12 months; the mean cylinder improved from -1.90 ± 1.10D to -0.31 ± 0.39D and -0.36 ± 0.43D, respectively. Eyes with oblique astigmatism also improved from a mean SE of -5.8 ± 3.4 D to -0.82 ± 1.50D and -0.69 ± 1.15D and a cylinder of -1.4 ± 0.73D to -0.17 ± 0.33D at 2 months and -0.1 ± 0.32D at 12. For ATR, the mean SE improved from -4.0 ± 1.8D to -0.08 ± 0.22D and -0.04 ± 0.12D; and the mean cylinder from -1.25 ± 0.53 to -0.02 ± 0.09D -0.08 ± 0.21D at 2 and 12 months, respectively. There were statistically significant improvements in SE, manifest sphere and cylinder refraction, and UDVA and CDVA scores for each cylinder type at 2 months with ATR cylinders having better outcomes. Although missing data limited interpretation at one year, differences were maintained. The magnitude of error calculations suggests that WTR was more prone to under-correction, particularly for high astigmatism (>1.5D). SMILE for myopic astigmatism reliably corrects SE, irrespective of the subtype of astigmatism.

Evaluation of long-term clinical outcomes after Toric Implantable Collamer Lens implantation.

To evaluate the long-term (8-10 years) outcomes of Toric Implantable Collamer Lens (TICL) surgery. Nagoya Eye Clinic, Nagoya, Aichi, Japan. Retrospective observational study. We enrolled patients who underwent TICL surgery from 2005-2009 to correct myopia and myopic astigmatism. The safety, efficacy, predictability, astigmatism correction efficacy, and complications were evaluated using preoperative, 1-year postoperative, and final examination data. We included 133 eyes of 77 patients. At the final visit, the mean uncorrected and corrected visual acuity were -0.01±0.2 and -0.17±0.05, respectively. The mean safety and efficacy indices were 0.91±0.26 and 0.68±0.21, respectively. The manifest astigmatism was -0.45±0.43 D. The mean corneal astigmatism change from 1 year post-surgery to the final visit was 0.40±0.26 D. Of the 38 eyes with a change in corneal astigmatism ≥0.5 D, 30 eyes (78.9%) changed to against-the-rule (ATR) astigmatism, one (2.6%) changed to oblique astigmatism, and seven changed (18.4%) to with-the-rule (WTR) astigmatism. The mean manifest astigmatism change from 1 year post-surgery to the final visit was 0.43±0.52 D. Of the 60 eyes with a change in manifest astigmatism ≥0.5 D, 25 (41.7%) changed to ATR astigmatism, 18 (30.0%) changed to oblique astigmatism, and 17 (28.3%) changed to WTR astigmatism. During follow-up, eight of 133 eyes (6.0%) developed anterior subcapsular cataracts, among which four (3.0%) underwent TICL removal and phacoemulsification and aspiration. No vision-threatening complications occurred. TICL surgery showed good long-term astigmatism-correcting effects, although the long-term uncorrected visual acuity decreased. The procedure was effective in correcting myopia and astigmatism.

Assessment of Pupil Size and Angle Kappa in Refractive Surgery: A Population-Based Epidemiological Study in Predominantly American Caucasians.

Purpose This retrospective study aims to establish normative values for pupil size, angle kappa, higher-order aberration, and astigmatism type in a largely Caucasian population in Utah, United States, utilizing the NIDEK OPD-Scan III system (Gamagori, Japan). Methods This study included 716 patients (1432 eyes) grouped based on spherical equivalence and age. Measurements were conducted under mesopic and photopic conditions. Statistical analysis involved Pearson's correlation and linear regression using the generalized estimating equation.NIDEK OPD-Scan III measured mesopic and photopic pupil size and angle kappa. The subjects were then grouped based on their spherical equivalence in diopters (D) and age in decades. The spherical equivalence groups were defined: >-6 D, -5.99to -3 D, -2.99to -0.25 D, -0.24to 0.24 D, and >0.25 D (range 0.25-5.75 D). The higher-order aberration groups were based on the reason for the visit: laser-assisted in situ keratomileusis, photorefractive keratectomy, and small incision lenticule extraction as one group; cataract evaluation; and keratoconus. Astigmatism measurements were grouped into with-the-rule (WRT), against-the-rule (ATR), and oblique astigmatism, with further subgrouping into a young cohort (20-40 years) and an old cohort (>65 years). Results Among 716 participants, 49.2% were men; the mean age was 42.1±15.5(range 7-88 years). The average spherical equivalence for myopia eyes was -3.28±2.34 D, and 1.51±1.46 D for hyperopia eyes. The mean mesopic pupil size was 5.68 ± 1.09 mm; the photopic pupil size was 4.65±1.09 mm. Pearson's correlation coefficient for mesopic pupil size versus age was -0.551, and -0.42 for photopic pupil (p < 0.001); sphere vs mesopic pupil size was -0.200, and -0.173 for photopic pupil(p < 0.001). The regression analysis for mesopic pupil size versus age revealed a 0.39 mm decrease in average pupil size per decade increase in age, and 0.25 mm decrease per decade for photopic pupil. The regression analysis for mesopic pupil size versus sphere revealed a 0.22 mm decrease in average pupil size per 3D increase in sphere, and a 0.16 mm decrease 3 D increase in sphere for the photopic pupil. The mean mesopic angle kappa was 0.33± 0.15 mm; photopic angle kappa was 0.31±0.15 mm. Pearson's correlation coefficient for mesopic angle kappa vs spherical equivalence was 0.32, and 0.296 for photopic angle kappa (p <0.001 for both). Regression analysis for mesopic angle kappa vs spherical equivalence demonstrated a 0.051 mm increase in angle kappa per 3 D increase in spherical equivalence, and a 0.048 mm increase for photopic angle kappa (p < 0.001 for both). Among the higher-order aberration groups, the keratoconus group exhibited the highest levels. In terms of astigmatism type, WRT astigmatism was the most common in the young cohort, while ATR astigmatism was most prevalent in the older cohort. Conclusions The results of this study reveal significant associations between pupil size and increasing age, as well as between pupil size and increasingly positive refractive errors. These findings hold particular clinical relevance to older patients and individuals with hyperopia, as they undergo photoablative corneal refractive surgery or multifocal intraocular lens implantation. Understanding the established normative values for pupil size, angle kappa, higher-order aberration, and astigmatism type can aid clinicians in making more informed decisions and improving patient outcomes.

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

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

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.

The Impact of Posterior Corneal Astigmatism on Surgically Induced Astigmatism in Cataract Surgery.

This study aimed to evaluate the changes in posterior corneal astigmatism after cataract surgery and provide a theoretical basis to accurately evaluate the total corneal astigmatism (TA) to be corrected before toric intraocular lens (IOL) implantation. Sixty-two patients (89 eyes) who underwent phacoemulsification combined with toric IOL implantation (AcrySof IQ Toric SN6AT2-T9) at Shanxi Eye Hospital between January 2017 and September 2018 were enrolled. Surgically induced astigmatism of the posterior cornea (SIAPA) was analysed using vector analysis during pentacam examination. The vector variances of keratometric astigmatism (KA), TA, and posterior corneal astigmatism (PA) preoperatively and postoperatively in the "with-the-rule (WTR) astigmatism" group and "overall patient" group were statistically significant (P < 0.05). A statistically significant difference was observed between surgically induced KA (SIAKA) and surgically induced astigmatism of the total cornea (SIATA) for all patients, including those with WTR astigmatism. For all patients, SIAKA was less than SIATA by 0.05 ± 0.21 D, and for patients with WTR astigmatism, SIAKA was less than SIATA by 0.09 ± 0.22 D. For patients in the "against-the-rule (ATR) astigmatism" group, there were no statistically significant differences between SIAKA and SIATA, although SIAKA was greater than SIATA by 0.03 ± 0.18 D. When PA ≤0.4 D or KA ≤2.0 D, SIAPA can be ignored. However, when PA >0.4 D or KA >2.0 D, ignoring SIAPA caused by cataract surgery incision will cause SIAKA in patients with WTR astigmatism to underestimate SIATA, while SIAKA in patients with ATR astigmatism will cause an overestimation of SIATA. SIA on the posterior corneal astigmatism may have a significant role on more precise planning of toric IOL implantation, especially in cases with higher preoperative anterior or posterior corneal astigmatism.

Comparison of surgically induced astigmatism in chevron, straight, and frown incisions in manual small-incision cataract surgery.

: The study was conducted to calculate and compare the surgically induced astigmatism (SIA) in chevron, frown, and straight incisions in manual small-incision cataract surgery (MSICS). A prospective, hospital-based study was conducted on 90 patients aged 50 years and above with nuclear sclerosis of grade 4 or more. Each group had 30 patients, divided into Group V (chevron incision), Group S (straight incision), and Group F (frown incision). Patients who had with-the-rule (WTR) astigmatism were operated on through a chevron or straight incision superiorly, while patients who had against-the-rule (ATR) astigmatism underwent MSICS through a temporal frown incision. The patients were followed up post-operatively on days 1, 7, 6 weeks, and 12 weeks, and at each visit, the uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and SIA were calculated and compared. The mean age of all the patients was 66.22 ± 8.05 years. BCVA of at least 6/18 or better at 12 weeks post-operatively was achieved in 29 patients (97%) in Group V, 28 patients (93%) in Group F, and 29 patients (97%) in Group S. The mean SIA in Group V was 0.34D ± 0.22D, in Group S was 0.97D ± 0.29D, and in Group F was 0.575D ± 0.25D. SIA by chevron incision is the least followed by the frown incision and straight incision. The superiorly placed chevron incision in WTR astigmatism provided optimal results for the best UCVA and minimal SIA. The temporal frown incision in ATR astigmatism also had good results.

Study of changes in pre-existing against-the-rule astigmatism after temporal manual small-incision cataract surgery using frown, straight, and smile incisions.

To assess the change in the amount of astigmatism caused by frown, straight, and smile incision in patients with pre-existing against-the-rule (ATR) astigmatism of more than and equal to 1 diopter. This is a prospective, comparative study conducted over 18 months on 60 patients. Twenty patients were allocated to each incision using simple random sampling. Demographic details, best-corrected visual acuity (BCVA), intraocular pressure (IOP), anterior and posterior segment evaluation, and A-scan were done. An average of three measurements of K horizontal (Khavg), K vertical (Kvavg), and difference between the two (Khavg - Kvavg) were taken using manual keratometry. All surgeries were performed by a single surgeon. All the data analyses were performed by using IBM Statistical Package for the Social Sciences (SPSS) version 20 software. Frequency distribution and cross tabulation were performed to prepare the tables. In frown incision, Khavg - Kvavg was significantly decreased on day 45 from the preoperative value (P &lt; 0.001), followed by straight incision (P &lt; 0.001), and smile incision (P &lt; 0.001). Maximum decrease was observed in frown incision (49.15%) followed by straight (37.75%) and smile (28.57%) incisions. Our results are consistent with reduction of pre-existing ATR astigmatism with temporal incisions, and frown incision seems to be the best approach.

Pattern of astigmatism using partial coherence interferometry in patients of different age groups undergoing cataract surgery

Astigmatism is a refractive error that accounts for 70% of refractive errors in the elderly population. It is important to be aware of the distribution, extent, and type of astigmatism in patients undergoing cataract surgery to guide in reducing postoperative spectacle dependency. To study the demography, amount, and pattern of astigmatism using partial coherence interferometry in patients of different age groups undergoing cataract surgery. A cross-sectional observational study. Keratometry and demography data were collected for patients planned for cataract surgery at a tertiary care center between January 2018 and December 2019. It was done with noncontact partial coherence interferometry in patients above 50 years undergoing cataract surgery. Out of 385 patients, 216 (56%) were males and 169 (44%) were females. Astigmatism was more common in males than females (P = 0.00). Against-the-rule (ATR) astigmatism was found in 262 cases (68%), while with-the-rule (WTR) astigmatism was seen in 87 cases (23%). ATR was more common than WTR (P = 0.00). The number of patients with ATR seems to be increased with aging eyes and was more common between 61 and 70 years of age group (P = 0.00). The total amount of astigmatism increased with increasing age (P = 0.00029) which was found to be significant. Frthermore, there was a gradual change of WTR to ATR astigmatism with aging eyes. Two hundred and sixty-two cases (68%) had ATR astigmatism mainly seen in the age group of 61-70 years. Majority had astigmatism up to 1.0 D that can be easily managed by simple cost-effective keratorefractive procedures like on-axis incision, opposite clear corneal incision, and limbal relaxing incisions.

Long-term outcomes of cataract surgery with toric intraocular lens implantation by the type of preoperative astigmatism

Surgical outcomes of toric intraocular lens (IOL) implantation for 8 years after surgery were analyzed. Data were retrospectively collected in 176 eyes of 176 patients before and 1 month, 1, 3, 5, and 8 years after phacoemulsification and implantation of a toric IOL. Preoperative corneal and postoperative manifest astigmatism was analyzed by converting to power vector notations; horizontal/vertical (J0) and oblique (J45) astigmatism components. Toric IOL implantation significantly reduced pre-existing astigmatism by decreasing J0 in eyes with preoperative with-the-rule (WTR) astigmatism, increasing J0 in eyes with against-the-rule (ATR) astigmatism, and correcting J45 in eyes with oblique astigmatism. After surgery, the eyes with preoperative ATR astigmatism showed a significant ATR astigmatic shift, and J0 at 5 and 8 years was significantly smaller than that at 1 month postoperatively. Uncorrected distance visual acuity was also significantly worse at 5 and 8 years than at 1 month postoperatively. In eyes with WTR and oblique astigmatism, the effects of toric IOLs on astigmatism and visual acuity were sustained for 8 years. The long-term astigmatism-correcting effects did not differ among the models of toric IOL used in this study, SN6AT3–8 (Alcon Laboratories). In eyes with preoperative ATR astigmatism, astigmatism-correcting effects of toric IOLs decreased at 5 years and later postoperatively, indicating that overcorrection may be considered at the time of cataract surgery. In eyes with WTR and oblique astigmatism, the effects of toric IOLs were maintained throughout the 8-year follow-up period.

Characterizing astigmatism in the United States.

To study astigmatism and astigmatism rule by (1) determining changes in prevalence in the United States between 1971 to 1975 and 1999 to 2008 and (2) identifying associations with demographic factors. National survey. Retrospective cross-sectional study. Participants of the 1971 to 1975 and 1999 to 2008 National Health and Nutrition Examination Survey (NHANES) aged 20 to 74 years representing the U.S population were included. The 1971 to 1975 NHANES measured astigmatism in participants using an algorithm based on presenting visual acuity, lensometry, and objective refraction. Similar methods were implemented using the 1999 to 2008 NHANES data for comparison. Prevalence of clinically significant astigmatism (≥1.0 diopters [D]) was identified, and logistic regression models were used to assess demographic associations with rule of astigmatism. A total of 3371 and 13 10 participants were included from the 1970s and 2000s NHANES. Main outcomes were prevalence estimates of astigmatism and odds ratios estimating associations with demographic characteristics. There was an increase in astigmatism from the 1970s to 2000s (14% [95% CI: 13.2-14.5] vs 24% [22.8-24.6], which was more pronounced in men (12% [10.8-12.7] vs 23% [21.9-24.2]) than in women (16% [14.9-16.8] vs 24% [23.0-25.7]). In adjusted analysis of the 2000s cohort, myopic patients had 8.34 (CI: 7.30-9.54) times greater odds of astigmatism than nonmyopic patients. In the 2000s, there was increased odds of against-the-rule (ATR) astigmatism in men (odds ratio [OR], 1.4; 95% CI: 1.1-1.8) compared with women, in nonmyopic patients (OR, 2.3; 95% CI: 1.7-3.1) compared with myopic patients, and in patients aged 60 to 74 years (OR, 3.7; 95% CI: 2.7-5.1) compared with those aged 20 to 39 years. There is greater prevalence of astigmatism and ATR astigmatism in 1999 to 2008 compared with 30 years before in the U.S. Factors associated with ATR astigmatism were being male, White, and nonmyopic.

Comparison of long-term astigmatic changes following cataract surgery among types of corneal astigmatism

AimsTo examine whether long-term corneal astigmatic changes after stabilisation of surgically induced astigmatism (SIA) following cataract surgery differ among eyes having against-the-rule (ATR), with-the-rule (WTR), and oblique astigmatism.MethodsAnterior corneal astigmatism...

Prediction of residual astigmatism in cataract surgery at different diameter zones using optical biometry measurement

The studies for astigmatism prediction error at different diameters using optical biometry are scant. We investigated patients who underwent cataract surgery with monofocal, nontoric intraocular lens (IOL) from 2017 through 2019 in a medical center. Patients with prior refractive surgeries, corneal opacity, or surgical complications were excluded. Corneal astigmatism (CA) was measured using AL-Scan at 2.4- and 3.3-mm diameter zones and calculated using the Barrett toric calculator preoperatively and postoperatively. The mean absolute error and centroid prediction error for the two zones were computed using double-angle plots. In total, 101 eyes of 76 patients were analyzed. Mean patient age was 68.7 ± 9.3 years and mean preoperative CA power was 0.7 ± 0.5 D. The overall centroid prediction error a 3.3 mm (0.09 ± 0.58 D@25) was significantly lower than that at 2.4 mm (0.09 ± 0.68 D@87) on the X-axis (P = 0.003). The 3.3-mm measurement also had a lower centroid prediction error than the 2.4-mm did for eyes with against-the-rule (ATR) and oblique astigmatism (P = 0.024; 0.002 on X-axis, respectively). The 3.3-mm measurement provided a more accurate CA estimation than the 2.4-mm did, particularly for ATR astigmatism. Diameter zone and astigmatism type should be considered crucial to precise astigmatism calculation.

Long-term changes in manifest refraction subsequent to cataract surgery.

To examine the long-term refractive changes after stabilization of surgically induced changes (SICs) subsequent to cataract surgery. Private hospital. Case-control study. Manifest refraction of 300 eyes of 300 patients who underwent phacoemulsification and 300 eyes of 300 age-matched and sex-matched patients without surgery was examined the day on which SICs stabilized (baseline) and ≥7 years postbaseline using an autorefractometer. Refraction was divided into 3 components: spherical power (M), vertical/horizontal astigmatism (J0), and oblique astigmatism (J45) using power vector analysis, and the components were compared between the 2 timepoints and between groups. Data of All 600 eyes were collected. In the surgery group, the mean M and J45 did not change significantly between baseline and ≥7 years postbaseline, but the J0 significantly decreased between the 2 timepoints (P < .001), indicating an against-the-rule (ATR) shift. In the nonsurgery group, the mean M significantly increased and J0 significantly decreased between the timepoints (P < .001), whereas J45 did not change significantly. The mean change in M between the 2 timepoints was significantly smaller in the surgery group (P < .001), whereas the changes in J0 and J45 did not differ significantly between the timepoints. Spherical power did not change and refractive astigmatism significantly changed toward ATR astigmatism during the more than 7-year follow-up after stabilization of SICs in pseudophakic eyes, whereas hyperopic and ATR shifts occurred in phakic eyes, and the astigmatic changes were comparable between pseudophakic and phakic eyes.