Corneal Astigmatism Research Articles (Page 1)

Corneal astigmatism frequently coexists with age-related cataract and may impair uncorrected distance visual acuity (UDVA) if not addressed during surgery. Limbal relaxing incisions (LRI) and toric intraocular lenses (toric IOL) are two common methods for astigmatism correction, but evidence comparing their effectiveness in patients with moderate regular astigmatism remains limited. A prospective study was conducted at Yuyao Maternity and Child Health Care Hospital between January and December 2024. Ninety-three patients aged 55-80 years with moderate regular corneal astigmatism undergoing cataract surgery were allocated to either the LRI group (n = 45) or the toric IOL group (n = 48) based on informed voluntary choice following standardized preoperative counseling. All procedures were performed by a single experienced surgeon. The primary outcome was residual refractive cylinder at 6 months postoperatively. Secondary outcomes included UDVA, best-corrected visual acuity (BCVA), corneal astigmatism (K2-K1), and subjective visual satisfaction. Both groups showed significant improvement in UDVA and reduction in refractive cylinder postoperatively. At 6 months, the toric IOL group had significantly lower residual cylinder (0.67 ± 0.28 D vs. 0.94 ± 0.30 D, P < 0.001) and superior UDVA (0.15 ± 0.03 vs. 0.20 ± 0.03 LogMAR, P < 0.001) compared to the LRI group. No differences in BCVA were observed. Subjective satisfaction was significantly higher in the toric IOL group (P = 0.009). Toric IOL provide more favorable refractive and subjective outcomes than LRI for correcting moderate astigmatism during cataract surgery. These findings support a personalized approach that considers visual expectations, cost, and access to technology.

Toric intraocular lenses (IOL) predictably correct corneal astigmatism and are an important part of the cataract and refractive surgeon's toolbox. Advances in toric IOL technology, preoperative biometry, IOL power calculations, and IOL alignment have resulted in excellent visual outcomes and achievement of spectacle independence. Despite these advancements, the primary challenges faced in toric IOL use remain choosing the optimal IOL toricity and properly aligning the IOL. Toric IOL are an effective way to correct corneal astigmatism, and advancements in lens selection and design have improved their functionality for patients. This review summarizes these advances and reports on upcoming technologies.

Comparison of Surgical Methods for the Correction of Low Amounts of Corneal Astigmatism during Cataract Surgery.

Biometric characteristics of pterygium patients compared to the general population.

To evaluate the efficacy and safety of modified four-flanged intrascleral fixation of foldable intraocular lenses (IOL) using a 1-inch 30-gauge needle for extraocular suture threading. This retrospective case series included 20 eyes of 20 patients who underwent four-flanged intrascleral IOL fixation using a 1-inch 30-gauge needle, with at least 6 months of follow-up. We modified the original Canabrava technique by inserting a foldable IOL through a 2.4-mm clear corneal incision with a standard injector and performing extraocular suture threading with a 1-inch 30-gauge needle. Collected data included uncorrected and best-corrected (UCVA, BCVA), intraocular pressure, spherical equivalent (SE), prediction error (PE), and corneal and lens astigmatism. Postoperative complications and IOL centration were also evaluated. Visual acuity improved significantly over the 6-month follow-up; mean preoperative logarithm of the minimum angle of resolution (logMAR) UCVA was 1.25 ± 0.66 (Snellen equivalent, 20/355) and improved to 0.35 ± 0.19 (20/45), and logMAR BCVA improved from 0.53 ± 0.38 (20/70) to 0.15 ± 0.09 (20/30) (p < 0.05). The mean postoperative SE at 6 months was -0.61 ± 1.08 diopters, and PE was -0.25 ± 0.86 diopters. No significant changes in endothelial cell density were observed. Corneal astigmatism remained stable, and lens astigmatism was reduced after surgery, although not significantly. Postoperative complications included one case each of hypotony and vitreous hemorrhage, both resolved with medical therapy. No IOL redislocation, decentration, tilt, or flange-related issues occurred. Modified four-flanged intrascleral IOL fixation using a 1-inch 30-gauge needle provides stable IOL fixation by pairing a robust suture with the smallest suitable needle. Extraocular suture threading reduces intraocular manipulation, simplifying the procedure and resulting in favorable visual outcomes and low complication rates.

PurposeTo determine whether localized retinal exposure to astigmatic blur is sufficient to drive compensatory changes in refractive and corneal astigmatism in developing chick eyes.MethodsOne hundred and thirty-six chicks were randomly assigned to nine groups combining three visual field conditions (full, horizontal, or vertical) and three lens treatments: with-the-rule (WTR) astigmatism (+2.00/−4.00 × 90), against-the-rule (ATR) astigmatism (+2.00/−4.00 × 180), or control (plano lens). Objective refraction and A-scan ultrasonography were measured at baseline (post-hatch day 5) and after 7 days of lens treatment, at which time corneal topography was also assessed. Data were analyzed using interocular differences (treated right eye minus untreated left eye) with two-way ANOVA.ResultsExposure to astigmatic blur induced significant compensatory changes in both refractive and corneal astigmatism, regardless of visual field extent. WTR blur elicited greater compensatory astigmatism than ATR blur (mean difference = 1.20 ± 0.16 DC, P < 0.001), with both conditions showing significant compensation compared to controls (P < 0.001). Visual field condition had no significant effect on astigmatic compensation (P ≥ 0.19). In contrast, spherical ametropia development was influenced by visual field exposure, with partial-field conditions inducing mild myopic shifts and deeper anterior chambers compared to full-field exposure (P < 0.001).ConclusionsLocalized retinal exposure to astigmatic blur is sufficient to drive compensatory changes in both refractive and corneal astigmatism, indicating that local retinal mechanisms can independently guide astigmatism compensation. In contrast, spherical refractive development appears to be modulated by the extent of visual field exposure.

Background: Pterygium is a common ocular surface disorder that not only affects cosmesis but also induces corneal astigmatism, leading to visual impairment. This study aimed to compare the effectiveness of CAG and AMG in reducing pterygium-induced corneal astigmatism and to evaluate postoperative complications associated with each technique. Methods: A prospective, comparative study was conducted on 60 patients with primary pterygium at the Upgraded Department of Ophthalmology, GMC, Jammu, from Oct.2016 to April 2017. Patients were randomly assigned to undergo pterygium excision followed by either CAG/AMG. Preoperative and postoperative assessments were conducted at multiple intervals up to six months. Results: Preoperatively, the mean pterygium size was similar in both groups. Postoperatively, corneal astigmatism showed a progressive decline in both groups. By the first postoperative day, astigmatism significantly decreased (p&lt;0.001), with further reductions at one week (p&lt;0.0001). At one month, the conjunctival autograft group demonstrated a slightly greater reduction (0.60±0.61 D) compared to the amniotic membrane group (0.84±0.68 D). By three months, astigmatism remained stable at 0.62±0.62 D and 0.98±0.72 D, respectively. However, the intergroup difference was not statistically significant at any time point (p&gt;0.05), indicating comparable efficacy in postoperative corneal curvature improvement. Postoperative complications were more frequent in the conjunctival autograft group, with significantly higher conjunctival hyperemia (63% vs. 26%, p=0.003), while other complications were comparable between groups. Conclusions: Both conjunctival autograft and amniotic membrane graft effectively reduced corneal astigmatism following pterygium excision.

To determine the factors that may affect pediatric epithelial remodeling after accelerated epi-off cross-linking (A-CXL) by examining the changes in epithelial thickness (ET) maps in pediatric keratoconus patients at the 1-year follow-up. Seventy-one eyes of 53 patients (mean age 14.89±1.89 years) were included. Before A-CXL, the MS-39 anterior segment optical coherence tomography images were examined 3, 6, and 12 months after corneal cross-linking (CXL). Significant flattening was observed in Kmax and Ksteep values at 6 and 12 months after A-CXL (P<0.05). No significant change was noted in mean ET, except for the 6 to 8 mm inferonasal area (P>0.05). When max-min ET differences were examined in each region of the corneal ET map, significant improvement was detected in the central 6 mm area, in the 2 to 4 mm inferior-temporal (IT) zone, and in the 4 to 6 mm area in the IT and inferior (I) zones (P<0.05). The change in max-min ET differences in the central 6 mm area before A-CXL and at 12 months after CXL was significantly correlated with the change in corrected distance visual acuity values, corneal keratometry, corneal astigmatism, and stromal thickness parameters (P<0.05). A-CXL is an effective treatment for preventing the progression of pediatric keratoconus and for normalizing ET changes by promoting epithelial remodeling. Epithelial remodeling may have an impact on the improvement in visual acuity after A-CXL by providing a smooth optical surface.

Objective: To investigate the differences and consistency in measuring corneal astigmatism between autorefractors and corneal topographers, as well as in assessing total ocular astigmatism among autorefractors, wavefront aberrometers, and subjective refraction devices, so as to provide a basis for clinical instrument selection for astigmatism measurements. Methods: A retrospective study was conducted. A total of 245 patients (245 right eyes) who underwent corneal refractive surgery and related examination at the Department of Ophthalmology, The Second Affiliated Hospital of Chongqing Medical University and Chongqing Mingda Eye Hospital from January 2015 to November 2023 were enrolled, including 85 males and 160 females, aged (32.17±10.16) years, with astigmatism degrees ranging from -4.50 to -0.25 D. The patients were divided into three age groups: 17-29 years (96 cases), 30-39 years (77 cases), and 40-50 years (72 cases). They were also classified based on the astigmatism degree:-0.25 to -0.75 D (131 eyes), -1.00 to -1.75 D (65 eyes), and ≤-2.00 D (49 eyes). Corneal astigmatism was measured using an autorefractor and a corneal topographer, while total ocular astigmatism was measured using an autorefractor, a wavefront aberrometer, and a subjective refraction device. The horizontal-vertical astigmatism vector (J0) and 45° oblique astigmatism vector (J45) of the cornea and the entire eye were calculated. Differences in corneal and total ocular astigmatism were compared. The Pearson correlation analysis of results from different instruments was performed, and the consistency was evaluated using the Bland-Altman analysis. Results: For corneal astigmatism, there were no statistically significant differences in J0 measurements in the 30-39 years group and J45 measurements in the 40-50 years group between the two instruments; however, statistically significant differences in J0 and J45 measurements were observed in other age groups and the overall population (all P<0.05). Moreover, no statistically significant differences were found in J0 and J45 measurements between the instruments in the ≤-2.00 D group, while statistically significant differences were present in other astigmatism groups and the overall population (all P<0.05). The results presented in a polar coordinate system showed that the measurement values of the two instruments were close in all groups and the overall population. The Pearson analysis indicated that J0 and J45 in all groups and the overall population were significantly correlated (all P<0.05). The consistency analysis revealed relatively good consistency in the 95% confidence interval (CI) of the 95% limits of agreement (LoA) for the overall results presented in a polar coordinate system. For total ocular astigmatism, statistically significant differences in J0 measurements among the three instruments were observed in all age groups and the overall population (all P<0.05). Regarding J45 measurements, only the 30-39 years group showed no significant difference among the autorefractor (P>0.05). In addition, there were statistically significant differences in J0 measurements among the three instruments in all astigmatism groups and the overall population (all P<0.05). Regarding J45 measurements, no significant difference was observed in the overall population and the -1.00 D to-1.75 D group (P>0.05). J0 and J45 in all groups and the overall population showed significant correlations between each pair of the three instruments (all P<0.05). The consistency analysis demonstrated that the upper limit of the 95%CI of 95% LoA for J0 in all groups and the overall population was <0.50 D, and most of the lower limits were <0.50 D; the 95%CI of 95% LoA for J45 in all measurements was within 0.50 D, indicating good consistency among the three instruments. Conclusions: In the undilated pupil state, the autorefractor and corneal topographer have a high correlation and relatively good consistency in measuring corneal astigmatism and can be mutually referential in clinical practice. The autorefractor, subjective refraction device, and wavefront aberrometer have a high correlation and good consistency in the measurements of total ocular astigmatism. Among them, the autorefractor and wavefront aberrometer (objective refraction) can provide references for the subjective refraction device (subjective refraction). Clinically, the selection can base on the applicable scope of the instruments and clinical requirements.

Background: Contact lens-assisted corneal cross-linking can be used to treat keratoconus in patients with thin corneas under measuring less than 400 µm. This study compares the long-term clinical and tomographic outcomes between accelerated corneal cross-linking (A-CXL) and accelerated contact lens-assisted corneal cross-linking (A-CACXL). Methods: Patients who underwent either A-CXL or A-CACXL protocol due to progressive keratoconus were enrolled in this retrospective cohort study conducted between January 2015 and December 2018. The control group (patients with minimum corneal thickness of at least 400 µm, comprising 32 eyes of from 32 patients) was treated with A-CXL, whereas the treatment group (patients that had minimum corneal thickness after epithelial removal below 400 µm; 30 eyes of from 30 patients) underwent the A-CACXL protocol. Clinical and tomographic data were obtained from a 3-year follow-up period. Results: At 3 years, both groups represented a significant gain in best-corrected visual acuity (from 0.32 to 0.18 LogMAR units for A-CXL, p = 0.001; from 0.51 to 0.33 LogMAR units for A-CACXL, p = 0.037). Furthermore, postoperative tomographic parameters (Kmax, Kmean, or corneal astigmatism) were comparable between the two protocols. Progression of keratoconus was halted among 87% of eyes in the A-CXL group and among 73% of eyes in the A-CACXL group (p = 0.2). Conclusions: A-CACXL treatment is an effective and safe option for patients with keratoconus and thin corneas, yielding long term outcomes comparable to those of A-CXL treatment for patients with a minimum corneal thickness of 400 µm following a 3-year follow-up.

BackgroundThe lens thickness-to-anterior chamber depth (LT/ACD) ratio remains underexplored, despite its significance in optimizing cataract surgical outcomes and stratifying the risk of potential complications in aging populations.AimThis study aimed to investigate the distribution patterns and determinants of the LT/ACD ratio in cataract patients.MethodsBilateral ocular biometrics of 715 cataract patients were measured using Lenstar LS-900. The LT/ACD ratios of the right and left eyes were analyzed separately, with the results for the left eyes used to validate those for the right eyes. The LT/ACD ratio was compared using the Mann–Whitney or Kruskal–Wallis test. Spearman’s correlation coefficients were used to evaluate its correlation with other biometrics. Univariable and multivariable linear regression analyses were performed to identify the determinants of the LT/ACD ratio.ResultsThe LT/ACD ratio was higher in women, in patients with shorter axial length (AL), and in older patients (all p < 0.0001). In both eyes, the LT/ACD ratio correlated with iris center distance, pupil size (PS), angle kappa, AL, and white-to-white corneal diameter (WTW) (all p < 0.05). Determinants of the LT/ACD ratio in the right eyes included age (β = 0.01), sex (β = −0.08), anterior corneal astigmatism (ACA) (β = 0.06), angle kappa (β = 0.30), and AL (β = −0.09). In the left eyes, determinants included age (β = 0.01), sex (β = −0.08), corneal curvature (CR) (β = −0.05), angle kappa (β = 0.20), AL (β = −0.12), and WTW (β = −0.12).ConclusionThe distribution patterns of the LT/ACD ratio varied with sex, AL, and age, and the LT/ACD ratio correlated with similar but distinct determinants in both eyes. These findings help us better understand the interaction between LT and ACD in the eyes of cataract patients.

ObjectiveTo quantify the distribution of anterior corneal eccentricity (e value) and identify associated factors in Chinese children and adolescents with astigmatism.MethodsCorneal topography data obtained using the Medmont E300 were retrieved from 961 participants aged 3 to 18 years, with corneal astigmatism (ΔK) ≥ 2.00 D. Data analysis included anterior corneal e values along both flat and steep meridians at 1–10 mm chord lengths, as well as the device-reported mean e values for the flat and steep meridians (9.35 mm chord dimater); anterior corneal keratometry readings (flat/steep K); ΔK; and refractive error. Demographic factors, including age and sex, were also analyzed.ResultsThis study included 961 right eyes (mean age: 7.9 ± 2.9 years; 56% male). The mean e values were 0.73 ± 0.10 for the flat meridian and 0.51 ± 0.21 for the steep meridian. Along the flat meridian, e values decreased and stabilized with increasing chord length, while along the steep meridian, a U-shaped trend was observed. The mean flat e was correlated with the flat K (β = −0.013, P < 0.001) and ΔK values (β = 0.037, P < 0.001), whereas the mean steep e was only associated with sex (β = −0.043, P = 0.001) in multivariate analyses.ConclusionIn Chinese children and adolescents with moderate to high corneal astigmatism, the anterior cornea demonstrates aspheric characteristics with distinct meridional asymmetry. The flat e value may was associated with corneal curvature (flat K and ΔK values), whereas the steep e value was not associated with these parameters.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12886-025-04402-3.

HighlightsWhat are the main findings?Modern high-resolution anterior segment tomographers are capable of extracting surface height data from the corneal front and back surfaces and from the epithelium–stroma interface.The higher refractive index of the corneal epithelium suggests that the cornea should be considered as a dual-layer structure to account for potential inhomogeneity in the epithelial thickness.What is the implication of the main finding?Model surfaces, such as floating best-fit spheres or conoids, could be fitted to the height map data within a specific region of interest to determine relevant surface characteristics such as curvatures, asphericities, and apex positions.Based on a dataset with bilateral repeat measurements in a cataractous population, we were able to confirm that the extracted surface characteristics seem to be very robust. However, surface asphericity should be extracted from a larger region of interest to ensure more robust data.We investigated the repeatability of the MS-39 in determining power vector components—the spherical equivalent (SEQ) and astigmatic powers (C0 and C45) and asphericity (Q)—of corneal epithelium, stroma, and endothelium in a large patient cohort. In this retrospective cross-sectional single-centre study, we evaluated a dataset containing 600 MS-39 anterior segment tomography measurements from 200 eyes (three repeat measurements each) taken prior to cataract surgery. The exported measurements included height map data for the epithelium, stroma, and endothelium surface. Model surfaces (spherocylinder (SphCyl), cylindrical conoid (CylConoid), and biconic (Biconic), all in the 3/6 mm zone) were fitted using nonlinear iterative optimisation, minimising the height difference between the measurement and model. The mean (MEAN) and standard deviation (SD) for each sequence of measurements were derived and analysed. In the 3 mm and 6 mm zone, the MEAN SEQ was 53.47/53.56/53.57 and 53.21/53.54/53.54 D for SphCyl/CylConoid/Biconic for the epithelium, −4.47/−4.51/−4.51 and −4.45/−4.50/−4.50 D for the stroma, and −6.23/−6.26/−6.26 and −6.18/−6.29/−6.30 D for the endothelium. With the three surface models and the 3/6 mm zone, the SD for SEQ/C0/C45 was in the range of 0.04 to 0.11/0.05 to 0.13/0.04 to 0.11 D for epithelium; 0.01 to 0.02/0.01 to 0.05/0.01 to 0.06 D for stroma; and 0.01 to 0.02/0.02 to 0.07/0.03 to 0.07 D for endothelium. Fitting floating model surfaces with astigmatism to map data of the corneal epithelium, stroma, and endothelium seems to be a robust and reliable method for extracting equivalent power and astigmatism using all the datapoints within a region of interest.

Background: Cataract, characterized by opacification of the crystalline lens, remains a leading cause of reversible blindness worldwide. Surgical intervention is the only effective treatment, with modern techniques shifting from large limbal incisions to smaller scleral approaches to improve wound healing and minimize surgically induced astigmatism. Comparative evaluation of incision size and position across surgical modalities is essential to optimize refractive outcomes and ensure faster visual rehabilitation. Objective: To compare post-surgical corneal astigmatism following phacoemulsification and manual small incision cataract surgery (SICS), focusing on incision position and incision length. Methods: A longitudinal study was conducted at LRBT Hospital, Lahore, between September 2022 and May 2023. A total of 140 patients aged 45–70 years were enrolled using non-probability convenience sampling. Participants were divided into two main groups: 70 underwent phacoemulsification and 70 underwent SICS. Each group was further subdivided into two subgroups of 35, based on incision position (superior or temporal) and incision length (1.75 mm or 2.75 mm). Visual acuity was assessed using a LogMAR chart, while corneal astigmatism was measured pre- and postoperatively using an autorefractometer and keratometer. Follow-up assessments were performed on Day 1, Week 1, and Week 6 post-surgery. Data were analyzed using Friedman’s and Mann–Whitney U tests in SPSS version 24. Results: Baseline mean visual acuity for the phacoemulsification group was 0.831±0.199 D, which improved to 0.467±0.218 D on Day 1, 0.353±0.184 D at Week 1, and 0.226±0.152 D at Week 6 (Friedman’s test=177.138, p=0.00). For the SICS group, baseline vision was 0.884±0.178 D, improving to 0.544±0.260 D, 0.437±0.228 D, and 0.280±0.196 D respectively (Friedman’s test=181.158, p=0.00). Mean cylindrical error in phacoemulsification decreased from 0.831±0.199 D at baseline to 0.182±0.914 D at Week 6 (p=0.00), while in SICS it decreased from 0.831±0.199 D to 0.136±0.962 D (p=0.000). Comparisons by incision length revealed no significant difference at 1.75 mm (p&gt;0.05), whereas at 2.75 mm phacoemulsification showed a significantly lower cylindrical error (p=0.007). Conclusion: Both phacoemulsification and SICS produced significant improvements in visual acuity and reductions in corneal astigmatism. Phacoemulsification offered faster rehabilitation and lower astigmatic error with larger incisions, while SICS demonstrated comparable outcomes at smaller incision sizes. Given its affordability and effectiveness, SICS remains a practical alternative in resource-limited settings.

BackgroudTo statistically analyze the distribution characteristics and related influencing factors of lens decentration and tilt in Chinese patients with age-related cataracts.MethodsThis cross-sectional study collected basic information and measurement results of patients with age-related cataracts scheduled for surgery. Axial length (AL) was recorded using the IOL Master 700. Corneal topography and lens biometrics were obtained using CASIA 2, and parameters including mean keratometry (Km), keratometric corneal astigmatism, white-to-white distance, horizontal angle-to-angle distance, anterior chamber depth, lens thickness (LT), lens decentration, lens tilt, anterior/posterior lens surface curvature radius (ALR/PLR), and lens equator diameter were documented. Univariate and multivariate regression analyses were conducted to evaluate the correlations between these ocular parameters and lens tilt and decentration.ResultsA total of 750 eyes from 750 patients were included. The lens tilted an average of 4.57° towards the inferotemporal direction, with an average decentration of 0.15 mm. Among these, 3.73% (28 eyes) exhibited tilt ≥ 7°, while 6.27% (47 eyes) showed decentration ≥ 0.3 mm. Multivariate regression analysis showed that lens tilt was negatively correlated with AL (p < 0.001) and PLR (p = 0.028). Lens decentration was positively correlated with age and AL, and negatively correlated with LT and ALR (all p < 0.001).ConclusionsIn patients with age-related cataracts, there is a certain degree of lens tilt and decentration. Greater lens tilt is associated with shorter AL and smaller PLR. Greater lens decentration is associated with longer AL, smaller ALR, thinner lens, and older age.

Purpose To evaluate the safety and efficacy of manual limbal astigmatic keratotomy (AK) compared to femtosecond laser-guided limbal astigmatic keratotomy (FLAK) to correct corneal astigmatism more than 3 diopters (D) after phacoemulsification. Study design Prospective, comparative, randomized, interventional study. Patients and methods This prospective study included 35 patients (40 eyes) divided into two groups. Group A included 16 patients (20 eyes) who had received FLAK and group B included 19 patients (20 eyes) who had received manual limbal AK using a diamond knife. All patients were suffering from corneal astigmatism after conventional phacoemulsification. This study was conducted from April 2024 to January 2025. Corneal astigmatism was measured by corneal tomography and Scheimpflug imaging (pentacam). Results The mean topographic corneal astigmatism was reduced from 4.78±1.4 to 1.78±1.31 D 3 months postoperatively in the FLAK group with a statistically highly significant difference ( P &lt;0.001) and from 4.93±1.03 to 1.98±1.31 D in the manual limbal AK group with a statistically highly significant difference ( P &lt;0.001). The mean topographic corneal astigmatism 3 months postoperatively showed a statistically nonsignificant difference between the two groups ( P =0.608). Although there was no statistically significant difference between the two groups, the mean arithmetic reduction of astigmatism was 3 D in the femtosecond AK group, which was higher than the mean arithmetic reduction of astigmatism in the manual AK group, which was 2.95 D. The surgery was uneventful in both groups with no adverse events. Conclusion FLAK and manual limbal AK are safe, predictable, and effective methods for correcting preexisting or surgically induced high degrees of corneal astigmatism after phacoemulsification, with the possibility to correct up to 4 D of corneal astigmatism.

Comparative analysis of three toric intraocular lenses: clinical outcomes and rotational stability in patients with corneal astigmatism

Abstract This study investigated the potential link between eye accommodation disorders and astigmatism by comparing the differences in astigmatism type – with-the-rule (WTR), against-the-rule (ATR) or oblique – and its origin (total, corneal, or lenticular) in 64 school-aged children (6–12 years; mean age 9 ± 2 years) diagnosed with accommodation disorders (hypofunction or hyperfunction) and a control group. Objective astigmatism was measured using the Huvitz Auto Ref/Keratometer HRK-1, and data from sphero-cylindrical notation were converted into Jackson crossed cylinder (JCC) vectors for further analysis. Keratometry data showed that corneal astigmatism in school-aged children was predominantly WTR. In contrast, refraction data, representing total astigmatism, revealed a more complex pattern: ATR astigmatism predominated in participants with accommodation hypofunction and in the control group, whereas WTR astigmatism was more common in participants with accommodation hyperfunction. Statistically significant differences were found in the astigmatism axis when comparing objective refractometry and the calculated lenticular astigmatism between the accommodation hyper-function and control groups. Notably, the hyperfunction group exhibited a tendency toward oblique astigmatism. These findings suggest a possible relationship between accommodation disorders and astigmatism axis orientation. However, due to the small samples and the observational nature of the study, the results should be interpreted as preliminary.

To investigate the effect of posterior corneal astigmatism measured with different biometers on toric intraocular lens (IOL) power calculation. This prospective case series study was conducted at Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. Patients undergoing measurements by the IOLMaster 700 (Carl Zeiss Meditec AG), CASIA2 (Tomey Corporation), and Pentacam AXL (Oculus Optikgeräte GmbH), uneventful cataract surgery, and toric intraocular lens (IOL) implantation were included. The prediction accuracy of the Barrett toric calculator with predicted and measured posterior corneal astigmatism (Barrett-PPCA and Barrett-MPCA, respectively) was evaluated. A total of 94 patients (94 eyes) were included. Both Barrett-PPCA and Barrett-MPCA with the IOLMaster 700 showed lower median absolute prediction errors (MedAEs) than with the CASIA2 (0.38 to 0.39 vs 0.63 to 0.67 D, both P < .001) and Pentacam AXL (0.38 to 0.39 vs 0.50 to 0.54 D, both P < .05). Similarly, Barrett-PPCA with the Pentacam AXL showed a lower MedAE than with the CASIA2 (0.50 vs 0.63 D, P = .026). There was no significant difference in MedAEs between Barrett-PPCA and Barrett-MPCA for the IOLMaster 700 (0.39 vs 0.38 D, P = .438). Barrett-PPCA showed lower MedAEs than Barrett-MPCA for the CASIA2 (0.63 vs 0.67 D, P = .006) and Pentacam AXL (0.50 vs 0.54 D, P < .001). The IOLMaster 700 exhibited the highest prediction accuracy for toric IOL compared to the CASIA2 and Pentacam AXL. When compared with Barrett-MPCA, Barrett-PPCA yielded comparable prediction accuracy for the IOLMaster 700 and improved accuracy for the CASIA2 and Pentacam AXL.

This studyaims to explore the relationships between key ocular optical parameters and corneal astigmatism, providing new insights into the factors influencing astigmatic changes in the human eye. The study was conducted at a tertiary eye care center with a population of adults. A cross-sectional, observational analysis of ocular measurements. A total of 935 adults (507 males, 428 females; aged 21-44 years) participated. Inclusion criteria were adults with no history of ocular disease or surgery. Exclusion criteria included individuals with systemic diseases affecting ocular health. Ocular measurements including central corneal thickness (CCT), anterior chamber depth (ACD), axial length (AL), lens thickness (LT), vitreous thickness (VT), white-to-white diameter (WTW), spherical power (SPH), and cylindrical power (CYL) were obtained using the Suoer SW-9000μm Plus biometer and Nidek ARK-1 Autorefractor. Corneal astigmatism (ΔK) was calculated as the difference between K2 and K1 within the 3mm optical zone. Shapiro-Wilk, Pearson correlation, and stepwise multiple linear regression analyses were applied. ΔK was significantly correlated with age (r = -0.07, p = 0.030), AL (r = 0.10, p = 0.002), VT (r = 0.10, p = 0.002), SPH (r = -0.13, p < 0.001), and CYL (r = -0.77, p < 0.001). After multicollinearity diagnostics, VT was excluded (VIF > 10). Multiple linear regression identified AL (β = -0.269, 95% CI: -0.415 to -0.123, p = 0.002, VIF = 3.75), SPH (β = 0.072, 95% CI: 0.012 to 0.132, p = 0.018, VIF = 3.39), and cylindrical power (β = -0.806, 95% CI: -0.909 to -0.703, p < 0.001, VIF = 2.31) as significant predictors, with an adjusted R² of 0.608. AL, SPH, and CYL significantly influence corneal astigmatism, suggesting corneal morphology is closely linked to ocular characteristics, which may aid in targeted approaches to diagnosis and management.