Astigmatism Research Articles

Corneal Epithelial Remodeling Following Cylinder Correction With SMILE or FS-LASIK: A Contralateral Comparative Study.

To compare the corneal epithelial remodeling in eyes with high astigmatism that had small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). Seventy-four patients with myopic astigmatism of greater than -2.00 diopters (D) and little binocular difference in spherical equivalent were included in this contralateral comparative study. All patients received SMILE in one eye and FS-LASIK in the other eye randomly. The corneal epithelial remodeling pattern was mapped using the latest RTVue spectral-domain optical coherence tomographer (Optovue) by region. Satisfactory refractive correction was achieved in all enrolled eyes with either SMILE or FS-LASIK. The corneal epithelium gradually thickened following surgical cylinder correction, distributing mainly along the flat medium. The corneal epithelium proliferation is milder centrally but more pronounced in the mid-peripheral area after SMILE, compared with FS-LASIK. The flat-steep difference in corneal epithelial thickness (CET) is evident in the mid-peripheral and peripheral areas, which is more obvious in SMILE. Residual cylinder was positively correlated with CET in eyes that had FS-LASIK, but not SMILE. More importantly, these epithelial changes were positively correlated with the ablation depth and higher order aberrations following surgical refractive correction. The postoperative CET map varied between SMILE and FS-LASIK. In eyes with high astigmatism, SMILE surgery is followed by milder and more stable corneal epithelial thickening. Moreover, the corneal epithelium is sensitive to stromal ablation and corneal remodeling is crucial to the postoperative visual quality. This study rigorously distinguished the CET difference between SMILE and FS-LASIK in astigmatic eyes and shed light on subsequent research. [J Refract Surg. 2024;40(10);e728-e741.].

Analysis of third and fourth corneal high-order aberrations before and after small incision lenticule extraction (SMILE) in myopic and myopic astigmatic eyes using ray tracing aberrometry

BackgroundAim is to analyze alterations in third and fourth corneal higher-order aberrations using a ray tracing aberrometer (iTrace) induced by SMILE (small incision lenticule extraction) refractive surgery on Algerian patients; and also to investigate how corneal aberrations vary with spherical equivalent (SE), corneal central thickness (CCT), and age. Design Prospective, non-randomized case series that were carried out at the Chiali Smile Center, Algiers, Algeria.ParticipantsA total of 219 eyes from 110 myopic patients, with and without astigmatism, successfully concluded the ultimate follow-up. Participants exhibited an average age of 32.48 years, with preoperative mean corneal high-order aberrations (CHOA) measuring 0.005 ± 0.036 μm.MethodsA tracking trend analysis of high-order aberrations (HOAs) was conducted on the three groups of patients, assessing total corneal high-order aberrations after SMILE over periods of two, six, and twelve months.ResultsA substantial increase in total corneal high-order aberrations following SMILE, with a P value < 0.05. Conversely, there was a noteworthy and significant decrease in vertical trefoil for all groups (P value = 0.000). Interestingly, the corneal higher-order aberrations were more pronounced after two months compared to the six and twelve-month intervals. Spherical aberration demonstrated a significant increase with the extent of preoperative myopia and preoperative spherical equivalent both before and after SMILE surgery (P < 0.05), particularly in cases of high myopia. Moreover, there were significant reductions in preoperative and postoperative vertical coma (P = 0.047, P = 0.004, respectively) corresponding to the degree of preoperative myopia, with a more substantial decrease in vertical coma observed in cases of low myopia.ConclusionIn the post-SMILE period, a notable increase in vertical coma and spherical aberrations was observed, accompanied by a significant decrease in vertical trefoil across all eyes. These aberration changes were identified to be closely associated with the spherical equivalent.

Analysis of PDE6G mutations in a patient with retinitis pigmentosa

BackgroundMutations in PDE6A and PDE6B are known to cause autosomal recessive RP in humans, On the other hand, mutations in PDE6G are rare but can lead to severe early-onset RP.Case presentationAn 8-year-old Chinese boy was referred to our hospital for poor vision issues. Refraction with cycloplegia showed high hyperopia with astigmatism both eyes. Funduscopic examination revealed typical bone spicule-type pigment deposits in the periphery and midperiphery. The patient was given glasses and a whole exome sequencing containing mitochondrial genes was performed. The results of genetic testing showed that there was a heterozygous frameshift mutation and a segment deletion in the proband’s PDE6G gene. Analysis of the parental genes showed that frameshift mutation was inherited from the proband’s mother and segment deletion from his father.ConclusionsIn this paper, we give a firsthand report that the complex heterozygous mutations of PDE6G gene can causes autosomal recessiveRP (arRP), which expands the understanding of the pathogenic genes of RP.

Rotational Stability, Footplate Position, and Visual Outcomes of Toric Implantable Collamer Lenses in Eyes With Low Vault.

To evaluate the clinical outcomes, rotational stability, and footplate position of the toric Implantable Collamer Lens (TICL) (STAAR Surgical) in eyes with low vault and analyze factors related to rotational stability. This prospective observational study included 59 eyes of 59 patients with insufficient vault (< 250 µm). Postoperative rotation was defined as the difference between the achieved angle and the intraoperative fixation angle, and assessed with a digital anterior segment photograph after full mydriasis at 1 week and 1, 3, and 6 months postoperatively. Ultrasound biomicroscopy was used to determine the ciliary body morphology and position of the footplate. Correlation analysis was employed to identify the risk factors associated with TICL rotation at 6 months postoperatively. At 6 months postoperatively, the mean central vault was 137.4 ± 61.0 µm (range: 40 to 236 µm), and the mean efficacy and safety indices were 1.04 and 1.15, respectively. The mean manifest refractive astigmatism decreased from -1.67 ± 0.82 diopters (D) preoperatively to -0.43 ± 0.33 D postoperatively, and the mean absolute rotation was 4.50 ± 3.08 degrees (range: 0 to 12.50 degrees). The angle of rotation was correlated with the preoperative spherical power (r = -0.318, P = .014), the average value of TICL footplates position (r = 0.284, P = .029), and postoperative astigmatism (r = -.469, P⩽ .001). TICL implantation is predictable, safe, and effective in correcting myopic astigmatism in eyes with low vault. The rotational stability was acceptable and related to the malposition of the footplate and preoperative spherical power. [J Refract Surg. 2024;40(7):e460-e467.].

Repeatability and Agreement of 4 Biometers Measuring Corneal Astigmatism in Eyes With Irregular Corneal Astigmatism Component

To investigate the repeatability and agreement of corneal astigmatism measurements in eyes with irregular corneal astigmatism component (ICAC) using four devices: IOLMaster 700 biometer, Lenstar 900 biometer, iTrace, and Pentacam. Prospective cross-sectional reliability analysis. Sixty-four eyes (52 patients) with ICAC were examined three times using the four devices. The eye with ICAC in this study is defined as the cornea has a certain degree of irregular astigmatism (asymmetric and/or skewed bowtie pattern of corneal topography according to corneal topography classification), accompanied with total corneal higher-order aberrations in the 4 mm zone of 0.3 µm or greater. Corneal astigmatism was evaluated using three categories: anterior corneal astigmatism (ACA), posterior corneal astigmatism, and total corneal astigmatism (TCA). The repeatability was determined using the ∆Ast (arithmetic mean of vector differences among three repeated corneal astigmatism measurements). Bland-Altman plots and astigmatism vector analyses were employed to assess agreement. The IOLMaster 700 (∆Ast = 0.27 ± 0.20 D) showcased higher repeatability in ACA measurements compared to iTrace (∆Ast = 0.37 ± 0.38 D, P = .040) and Pentacam (∆Ast = 0.50 ± 0.22 D, P < .001), and paralleled the performance of Lenstar 900 (∆Ast = 0.31 ± 0.26 D, P = .338). The Pentacam (∆Ast = 0.09 ± 0.07 D, P < .001) demonstrated superior repeatability in posterior corneal astigmatism, whereas the IOLMaster 700 (∆Ast = 0.33 ± 0.23 D, P < .001) excelled in TCA. The IOLMaster 700 exhibited good agreement with either Lenstar 900 or iTrace, characterized by narrow 95% limits of agreement and clinically acceptable vector differences. Conversely, vector differences between Pentacam and the other three devices in ACA and TCA measurements were clinically significant, exceeding 0.50 D (all P < .05). In terms of repeatability of corneal astigmatism measurements in eyes with ICAC, the IOLMaster 700 and Lenstar 900 outperformed iTrace and Pentacam. While the IOLMaster 700 can be used interchangeably with either Lenstar 900 or iTrace, the Pentacam is not interchangeable with the other three devices.

Non-diffractive, toric, extended depth-of-focus intraocular lenses in eyes with low corneal astigmatism

BackgroundTo assess clinical outcomes after implanting toric, extended-depth-of-focus intraocular lenses (IOLs) to correct low corneal astigmatism in eyes with cataracts.Methods47 eyes were implanted with the AcrySof IQ Vivity Toric DFT215 IOL. Main outcome measures were refractive error, monocular uncorrected and corrected distance (UDVA/CDVA), uncorrected and distance-corrected intermediate (UIVA/DCIVA), and uncorrected near and distance-corrected near (UNVA/DCNVA) visual acuities, monocular defocus curve, rotational stability, and IOLSAT and QUVID questionnaires. Patients were assessed at 3 months postsurgery.ResultsAll eyes had a postoperative spherical equivalent (SE) within ± 0.50 D and 97.87% (n = 46) had a refractive cylinder ≤ 0.50 D. The mean SE and refractive cylinder were − 0.10 ± 0.17 D and − 0.16 ± 0.24 D, respectively. The CDVA was ≥ 20/25 and ≥ 20/32 in 95.74% (n = 45) and 97.87% (n = 46) of eyes, respectively. The DCIVA was ≥ 20/32 in 85.11% (n = 40) of eyes and the DCNVA was ≥ 20/40 in 74.47% (n = 35). The mean values of CDVA, DCIVA, and DCNVA were − 0.02 ± 0.08, 0.14 ± 0.09, and 0.23 ± 0.12 logMAR, respectively. The defocus curve revealed good visual acuity at far and intermediate distances with a depth-of-focus of about 1.75 D. IOL rotation was 0.74 ± 1.13 degrees and all eyes had a rotation of less than 5 degrees. Patients reported either good or very good postoperative vision without eyeglasses under bright-light-conditions at distance (87.80%, 36/41) and intermediate distance (92.68%, 38/41). Between about 63.83%–72.34% (30–34) of patients reported no starburst, halos, or glare, or if experienced, were not bothersome.ConclusionsThe Vivity toric IOL implanted in eyes with low-astigmatism provides accurate refractive outcomes, good visual acuity at different distances and excellent rotational stability.Trial Registration The study was registered with the German Clinical Trials Register (DRKS00030579)

Comparison of keratometric values and anterior segment parameters measured using Scheimpflug Sirius topography and Lenstar biometry.

This study aimed to evaluate the consistency of preoperative keratometric values, anterior segment, and intraocular lens (IOL) power measurements in patients with cataract and no comorbidities using the Sirius topography device (CSO, Italy) and Lenstar LS 900 (Haag-Streit AG, Köeniz, Switzerland). Patients with grade 2 and 3 cataracts who applied to Ophthalmology Clinic of Dışkapı Yıldırım Beyazıt Education and Research Hospital, University of Health Sciences and planned for cataract surgery were included the study. Forty eyes with cataract from 40 patients were taken in the study. All patients underwent preoperative assessment using a combined Scheimpflug-Placido disc-based tomography device (Sirius) and Lenstar before cataract surgery. Keratometric measurements, such as flat keratometry (K1), steep keratometry (K2), and maximum keratometry (Kmax), and anterior segment parameters, white-to-white (WTW) distance, IOL power, astigmatism (AST), anterior chamber depth (ACD), aqueous depth (AD), and central cornea thickness (CCT), were recorded. There were significant differences between K1Lenstar and K1Sirius, K2Lenstar and K2Sirius, KmaxLenstar and KmaxSirius, WTWLenstar and WTWSirius, and IOL powerLenstar versus IOL powerSirius. However, there were insignificant differences between ASTLenstar and ASTSirius, ACDLenstar versus ACDSirius, ADLenstar and ADSirius, and CCTLenstar and CCTSirius variables. Furthermore, it was found that Sirius measured significantly higher than Lenstar, especially in terms of IOL power. Significant differences were observed between Lenstar and Sirius in terms of keratometric values, WTW distance, and IOL power. The IOL power value measured with Sirius was found to be higher than the IOL power value measured with Lenstar.

VISUAL AND REFRACTIVE OUTCOME OF NEW GENERATION SMALL INCISION LENTICULE EXTRACTION (SMILE) IN MYOPIA AND MYOPIC ASTIGMATISM

Introduction: Two main options for the surgical correction of high myopia and myopic astigmatism are corneal refractive surgery and implantation of phakic intraocular lens (IOL). Small Incision Lenticule Extraction (SMILE) is becoming more popular technique which includes a minimally invasive flap-free procedure. The aim of this study is to evaluate the visual and refractive outcome of New Generation SMILE in myopia and myopic astigmatism. Methods: This is an observational retrospective study in patients who underwent SMILE using Visumax 800 Femtosecond laser procedure at Undaan Eye Hospital in period December 2022 to February 2023. Pre and post operative uncorrected visual acuity (UCVA), spherical equivalent (SE), astigmatism value, keratometry and intra ocular pressure (IOP) were evaluated at 1 day, 1 week and 1 month follow-up. Results: The study comprised 30 eyes of 15 patients age from 18 to 32 years old. The mean post operative UCVA was significantly improved to 0.03 ± 0.06 logMAR at 1-day, 0.02 ± 0.04 logMAR at 1-week and -0.01 ± 0.02 logMAR at 1-month follow-up compared to preoperative UCVA 1.35 ± 0.23 logMAR (p&lt;0.001). The mean refractive spherical equivalent was significantly changed from -4.60 ± 1.47 D preoperatively to -0.57 ± 0.38 D at 1-month follow up (p &lt; 0.001). The mean refractive astigmatism decreased from -1.02 ± 0.66 D preoperatively to -0.34 ± 0.25 D at 1- month follow up (p&lt;0.001). Conclusion: New Generation of SMILE has shown good visual and refractive outcome for the correction of myopia and myopic astigmatic eyes since the early phase after surgery.

Clinical Results of a Monofocal Aspheric Bitoric Intraocular Lens with Plate Haptics in Hyperopic Eyes.

To assess the refractive and visual outcomes of hyperopic and astigmatic eyes implanted with a monofocal, aspheric, bitoric intraocular lens (IOL) with plate haptics following cataract surgery. The study evaluated 51 eyes implanted with the AT TORBI 709M IOL (Carl Zeiss Meditec AG, Jena, Germany) during a follow-up of 12-months. Refractive error, rotational stability, monocular uncorrected distance visual acuity (UDVA), monocular corrected distance visual acuity (CDVA), and contrast sensitivity were analyzed at 1-, 6-, and 12-months post-surgery. At 12 months, the cumulative CDVA was 20/25 in 94.12% of eyes and 20/32 or better in 98.04%. The UDVA was the same as, or better than, the CDVA in 88.24% of eyes. The mean logMAR UDVA and CDVA values were 0.06 ± 0.11 and 0.00 ± 0.08, respectively. In addition, 92.16% of eyes were within ±0.50D and 98.04% were within ±1.00D of a spherical equivalent, and 86.27% of eyes had refractive astigmatism ≤0.50D and 100% were ≤1.00D. The mean spherical equivalent was 0.21 ± 0.31D and the mean refractive cylinder 0.34 ± 0.27D. The IOL rotation was 1.18 ± 1.35 degrees and all eyes had a rotation ≤5 degrees. The log contrast sensitivity functions were good and similar for all spatial frequencies during follow-up. Our results demonstrate that implantation of the AT TORBI 709M IOL in hyperopic and astigmatic eyes is effective and safe. The visual and refractive outcomes were good, showing excellent rotational stability.

Symmetrical femtosecond laser arc incision in correcting corneal astigmatism in cataract patients.

To evaluate the effect of symmetrical arc incision correcting corneal astigmatism in femtosecond laser-assisted phacoemulsification (FLACS). This study enrolled patients with cataract combined with regular corneal astigmatism of >0.75 D, who underwent FLACS. Symmetrical arc incision was set at 8 mm diameter and 85% depth. The follow-up time was 3-24mo (4.92±3.49mo). Pentacam recorded the corneal astigmatism and higher-order aberration at pre-operation and post-operation. The changes in corneal astigmatism were analyzed by Alpins method. The correlation of astigmatism type, age, corneal horizontal diameter, corneal thickness, arc incision length, and correction index (CI) was analyzed, and the residual corneal astigmatism was compared with the residual whole eye astigmatism. Totally 79 patients (102 eyes) were enrolled, 10 patients had corneal epithelial injury, 1 patient occurred corneal epithelial hyperplasia. The corneal astigmatism was 1.23±0.38 D pre-operation, and decreased to 0.76±0.39 D post-operation (t=10.146, P=0.000). Corneal high-order aberration was 0.17±0.08 µm pre-operation and 0.24±0.11 µm post-operation (t=-5.186, P=0.000). The residual corneal astigmatism and residual whole eye astigmatism were no significant difference (t=-0.347, P=0.729). Using Alpin's method, the following were determined: target-induced astigmatism (TIA) =1.23±0.38 D, surgery-induced astigmatism (SIA) =0.77±0.45 D, difference vector (DV)=0.77±0.39 D, and CI=0.54±0.28. Age, astigmatism size, corneal horizontal diameter, corneal thickness, and arc incision length were not correlated with CI. The CI for against the rule astigmatism (ATR) was better than that for with the rule astigmatism (WTR; P=0.001). Femtosecond laser-assisted astigmatic keratotomy has better CI of ATR, but increase higher-order corneal aberration. CI is not ideal, it's not a perfect choice if we pursue ideal correction effect.

Simulation model for advanced astigmatism corrective eyeglasses and contact lenses

Mathematical eye models are crucial for developing treatment strategies for astigmatic eye conditions. Extensive research has been conducted on various treatment techniques, and also various surfaces in glasses and contact lenses. This study aims to address the existing research gap by optimizing mathematical eye models for specific astigmatic conditions. Using Liu and Brennan's model, we simulate the correction of astigmatism with glasses and contact lenses. We optimize toroidal and aspherical lens surfaces to maximize their effectiveness in correcting astigmatism and evaluate image quality using modulation transfer function (MTF), point spread function (PSF), and focal spot diagrams. Our results show that both glasses and contact lenses can effectively treat astigmatism, with glasses providing superior correction. However, individual factors such as oblique vision, decentration, and anterior surface asphericity can influence treatment outcomes. This study contributes to advancing ophthalmology by integrating computational models with clinical data to improve treatment planning and personalization.

Age-Related Changes in Total Corneal Astigmatism in Eyes With High Myopia.

The purpose of this study was to compare age-related changes in corneal astigmatism in eyes with and without high myopia. Eight-hundred eyes with high myopia (axial length ≥26.0 mm) and 800 eyes without high myopia (200 eyes each from patients in their 40s, 50s, 60s, and ≥70s) underwent videokeratographic examination. The amounts of vertical/horizontal (Rx) and oblique astigmatism (Ry) components, irregular astigmatism, and corneal shape were compared between eyes with and without high myopia and among age categories. In both groups, the mean Rx significantly changed to more positive with age ( P < 0.001), whereas the Ry did not change significantly. The Rx was significantly more negative in the high myopia group than in the control group in all age categories ( P ≤ 0.003), whereas the Ry did not differ significantly. The mean changes in the Rx and Ry during each 2 consecutive decades did not differ significantly between groups. The asymmetry and higher-order irregularity components increased with age ( P ≤ 0.001) but did not differ significantly between groups, except for the higher-order irregularity in patients in their 60s ( P = 0.018). In the averaged map, the corneal shape changed from with-the-rule to against-the-rule astigmatism with age in both groups, but the changes occurred later in the high myopia group. Age-related changes from with-the-rule to against-the-rule astigmatism occurred later in eyes with high myopia compared with eyes without high myopia in middle or older aged patients, but this change in each age decade was comparable between eyes with and without high myopia.

Supporting suture combined scleral fixation of toric IOL implantation in traumatic aniridia, aphakia and corneal astigmatic eye: a case report.

Supporting suture combined scleral fixation of toric IOL implantation in traumatic aniridia, aphakia and corneal astigmatic eye: a case report.

Outcomes of peripheral corneal relaxing incisions for residual astigmatism in patients after cataract surgery.

To evaluate the outcomes of peripheral corneal relaxing incisions (PCRIs) for correcting residual astigmatism in eyes after cataract surgery. Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. Retrospective case series. Retrospectively, we reviewed all consecutive cases that had previous cataract surgery and subsequent PCRIs by 1 surgeon. The PCRI length was determined according to a nomogram based on age and manifest refractive astigmatism. Visual acuity and manifest refractive astigmatism before and after the PCRIs were compared. Vector analysis was performed, and net refractive changes along the incision meridian were calculated. Criteria were met by 111 eyes. After the PCRIs, mean uncorrected visual acuity was significantly improved, and the percentage of eyes with uncorrected distance visual acuity of ≥20/20 increased significantly by 36%; the mean refractive astigmatism magnitude decreased significantly, and the percentages of eyes with refractive cylinder of ≤0.25 diopters (D) and ≤0.50 D increased significantly by 63% and 75%, respectively (all P < .05). The vector magnitude difference between pre- and post-operative refractive astigmatism was 0.88 ± 0.38 D. The postoperative refractive astigmatism had significantly smaller centroid and variance values than the preoperative refractive astigmatism ( P < .05). PCRIs are an effective approach for correcting low amounts of residual astigmatism in patients after cataract surgery.

Analysis of biometric parameters of cataract eyes measured with optical biometer Lenstar LS900, IOL Master 700, and OPD-SCAN III

BackgroundTo compare the characteristics of biometric measurements among the LS900, IOL Master, and OPD-SCAN III in patients with mild-to-moderate cataract. MethodsWe recruited 85 eyes of 78 patients diagnosed with mild-to-moderate cataract at our hospital between January and April 2023. The K (average corneal curvature; K1 and K2), astigmatism (AST), and white to white (WTW) were measured using those three devices, respectively. Differences and correlations between those measures based on the device were explored. ResultsThe K1, K2, and AST were highly consistent among the groups (P = 0.851, P = 0.626, P = 0.473, respectively). The WTW measured by IOL Master were larger than those measured by the LS900 and OPD-SCAN III (all P < 0.001). However, all three devices were highly correlated in all measures (P < 0.001). Bland-Altman plots indicated a significant agreement between three devices in all measurements (P < 0.001). ConclusionsK1, K2, and AST in patients with mild-to-moderate cataract were similar among all three devices, whereas the WTW were not. WTW measurement differences between three devices should be concerned in cataract cases.

Outcomes of preloaded toric intraocular lens implantation in eyes undergoing phacoemulsification.

To evaluate the clinical outcomes of preloaded toric intraocular lens (IOLs) implantation in eyes undergoing phacoemulsification. This prospective study included 51 eyes of 51 patients with visually significant cataracts and corneal astigmatism ranging between 0.75 and 5.50 D. All patients underwent phacoemulsification with SupraPhob toric intraocular lens implantation under topical anesthesia. The main outcome measures were uncorrected distance visual acuity (UDVA), residual refractive cylinder, spherical equivalent, and IOL stability at 3 months follow-up. At 3 months, 49% (25/51) of patients had UDVA equal to or better than 20/25 with 100% of eyes achieving better than 20/40. Mean logMAR UDVA improved from 1.02 ± 0.39, preoperatively to 0.11 ± 0.10 at 3 months follow-up (P < 0.001, Wilcoxon signed-rank test). The mean refractive cylinder improved from - 1.56 ± 1.25 D preoperatively to - 0.12 ± 0.31 D at 3 months follow-up (P < 0.001) while the mean spherical equivalent value changed from - 1.93 ± 3.71D preoperatively to - 0.16 ± 0.27D (P = 0.0013). The mean root mean square value for higher order aberrations was 0.30 ± 0.18 μm while the average contrast sensitivity value (Pelli-Robson chart) was 1.56 ± 0.10 log unit, at the final follow-up. The mean IOL rotation at 3 weeks was 1.7 ± 1.61 degrees, which did not change significantly at 3 months (P = 0.988) follow-up. There were no intraoperative or postoperative complications. SupraPhob toric IOL implantation is an effective method for addressing preexisting corneal astigmatism in eyes undergoing phacoemulsification with good rotational stability.

Meridional Attentional Asymmetries in Astigmatic Eyes.

To investigate the impact of attention orientation in young myopic adults with astigmatism. The effect of attention on foveal meridional performance and anisotropy was measured in corrected myopes with various levels of astigmatism (with-the-rule astigmatism ≤ -0.75D, Axis: 180 ± 20) using orientation-based attention. Attention was manipulated by instructing subjects to attend to either the horizontal or the vertical line of a central pre-stimulus (a pulsed cross) along separate blocks of trials. For each attention condition, meridional acuity and reaction times were measured via an annulus Gabor target situated remotely from the cross and presented at random horizontally and vertically in a two-alternative forced-choice employing two interleaved staircase procedures (one-up/one-down). Attention modulations were estimated by the difference in performance between horizontal and vertical attention. Foveal meridional performance and anisotropy were strongly affected by the orientation of attention, which appeared critical for the enhancement of reaction times and resolution. Under congruent orienting of attention, foveal meridional anisotropy was correlated with the amount of defocus for both reaction time and resolution, demonstrating greater vertical performance than horizontal performance as myopia increased. Compatible with an attentional compensation of blur through optimal orienting of attention, vertical attention enhanced reaction times compared to horizontal attention and was accompanied by an increase in overall acuity when myopia increased. Increased astigmatism was associated with smaller attention effects and asymmetry, suggesting potential deficits in the compensation of blur in astigmatic eyes. Collectively, attention to orientation plays a significant role in horizontal-vertical foveal meridional anisotropy and can modulate the asymmetry of foveal perception imposed by the optics of the eye in episodes of uncorrected vision. Further work is necessary to understand how attention and refractive errors interact during visual development. These results may have practical implications for methods to enhance vision with attention training in myopic astigmats.

Influence of Upper Eyelid Surgeries on Corneal Morphology Detected with Pentacam.

To analyze the corneal morphological parameters before and one month after the upper eyelid (UE) blepharoplasty and external levator resection (ELR) for ptosis surgery. Seventy eyes of 70 patients with dermatochalasis (50 eyes) and acquired aponeurotic ptosis (AAP) (20 eyes) included in this prospective study. Detailed ophthalmologic examination was performed including the best corrected visual acuity (BCVA), slit lamp examination and dilated fundoscopy. Measurements were made before and one month after the surgeries using Pentacam. Central corneal thickness (CCT), pupil center pachymetry (PCP) and thinnest pachymetry (TP), cornea front astigmatism (AST), flat keratometry (K1), steep keratometry (K2) and mean keratometry (Km) values were evaluated. Higher postoperative Km measurements were observed in dermatochalasis (p = 0.038) patients. Postoperative AST values were significantly lower in both dermatochalasis and ptosis cases (p = 0.034, p = 0.003, respectively). Increased PCP and TP were found in the AAP patients (p = 0.014, p = 0.015, respectively). UE blepharoplasty and ELR surgeries both lead to some significant changes on corneal structure post-operatively. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Changes in aberrations and biomechanics after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) in eyes with high astigmatism: a retrospective case control study

Background:To compare the 6-month changes in aberration and biomechanics after femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for high astigmatism.Methods:In this retrospective case control study, 47 eyes with high astigmatism (≥ 2.5 D, HA group) and 47 eyes with low astigmatism (≤ 1.0 D, LA group) underwent FS-LASIK. Preoperative and follow-up examinations included visual outcomes, higher order aberrations (HOAs) and biomechanics. Biomechanical parameters include a deformation amplitude ratio of 2 mm (DA ratio 2 mm), integrated inverse radius (IIR), stiffness parameter at first applanation (SP-A1), and ambrosio relational thickness through the horizontal meridian (ARTh).Results:Six months postoperatively, there was no significant difference in the efficacy and safety index (both P > 0.05) between the two groups, but the cylinder was higher in the HA group. The HOAs increased significantly after surgery in both groups (all P < 0.05). Six months postoperatively, the changes in spherical aberration and HOAs were larger in the HA group (both P < 0.005), but there was no significant difference between the changes in coma (P > 0.05). Significant decreases in SP-A1 and ARTh and significant increases in the IIR and DA ratio of 2 mm (all P < 0.05) were observed after surgery in both groups. The changes in the DA ratio 2 mm, IIR, SP-A1, and ARTh were not significantly different between the groups.Conclusion:FS-LASIK had relative comparable efficacy and safety in correcting high and low myopic astigmatism, with higher astigmatic under-correction in eyes with high astigmatism. High astigmatism in eyes after FS-LASIK could introduce larger corneal aberrations, but the impact on corneal stiffness was the same as that in eyes with low astigmatism.

Comprehensive comparisons of ocular biometry: A network-based big data analysis

PurposeTo systematically compare and rank ocular measurements with optical and ultrasound biometers based on big data.MethodsPubMed, Embase, the Cochrane Library and the US trial registry (www.ClinicalTrial.gov) were used to systematically search trials published up to October 22nd, 2020. We included comparative studies reporting the following parameters measured by at least two devices: axial length (AL), flattest meridian keratometry (Kf), steepest meridian keratometry (Ks), mean keratometry (Km), astigmatism (AST), astigmatism vectors J0 and J45, anterior chamber depth (ACD), aqueous depth (AQD), central corneal thickness (CCT), corneal diameter (CD) and lens thickness (LT). A network-based big data analysis was conducted using STATA version 13.1.ResultsAcross 129 studies involving 17,181 eyes, 12 optical biometers and two ultrasound biometers (with both contact and immersion techniques) were identified. A network meta-analysis for AL and ACD measurements found that statistically significant differences existed when contact ultrasound biometry was compared with the optical biometers. There were no statistically significant differences among the four swept-source optical coherence tomography (SS-OCT) based devices (IOLMaster 700, OA-2000, Argos and ANTERION). As for Ks, Km and CD, statistically significant differences were found when the Pentacam AXL was compared with the IOLMaster and IOLMaster 500. There were statistically significant differences for CCT when the OA-2000 was compared to Pentacam AXL, IOLMaster 700, Lenstar, AL-Scan and Galilei G6.ConclusionFor AL and ACD, contact ultrasound biometry obtains the lower values compared with optical biometers. The Pentacam AXL achieves the lowest values for keratometry and CD. The smallest value for CCT measurement is found with the OA-2000.