Refractive Astigmatism Research Articles

Comparison of accuracy of a toric calculator with predicted vs measured posterior corneal astigmatism.

To compare the accuracy of postoperative residual astigmatism prediction using the Barrett toric calculator with predicted vs measured posterior corneal astigmatism (PCA). Cullen Eye Institute, Baylor College of Medicine, Houston, Texas. Retrospective case series. We included 602 eyes with monofocal nontoric intraocular lens implantation. Biometry and PCA were obtained from the IOLMaster 700. Anticipated postoperative refractive astigmatism was calculated with the Barrett toric calculator for predicted and measured PCA, and the astigmatism prediction errors (PEs) for each were calculated using vector analysis. The vector PE magnitudes and percentage of eyes within certain amounts of vector PEs were compared between 2 methods. Compared with the Barrett toric calculator with predicted PCA, the Barrett toric calculator with measured PCA produced significantly smaller mean vector PE (0.54 diopter [D] vs 0.57 D) and higher percentage of eyes with vector PE of ≤0.5 D (57.6% [347/602] vs 52.5% [316/602]) (both P < .05). In eyes with predicted residual astigmatism of ≥0.5 D, the Barrett toric calculator with measured PCA again yielded a significantly higher percentage of eyes with vector PE of ≤0.5 D (51.2% [226/441] vs 44.7% [197/441], P < .05). Accuracy of residual astigmatism prediction is improved using the Barrett toric calculator with measured PCA rather than predicted PCA.

Visual Performance of Eyes with Residual Refractive Errors after Implantation of an Extended Vision Intraocular Lens.

To analyze the tolerance on distance vision of different combined residual astigmatic situations in patients implanted with a novel wavefront shaping extended depth of focus (EDoF) intraocular lens (IOL). The study included patients implanted with the Acrysof® IQ Vivity® IOL. Uncorrected (UDVA) and corrected distance visual acuity (CDVA) were measured three months after surgery, considering CDVA as the reference situation of the study. Distance VA was also measured in different refractive situations: (A) with 0.50 diopters (D) of positive (myopization) and negative (hyperopization) defocus and (B) with a residual mixed astigmatic refraction induced by adding a combination of -0.25 D spherical and 0.50 D cylindrical lenses placed in vertical (against the rule-ATR), oblique, and horizontal (with the rule-WTR) positions. The study included 30 eyes of 30 patients. UDVA and CDVA were -0.04 ± 0.05 and -0.05 ± 0.05 logMAR, respectively. VA values with +0.50 D and -0.50 D of defocus were 0.01 ± 0.06 and 0.00 ± 0.04 logMAR, respectively. VA was better with distance correction (p < 0.001) and no differences were found between the myopic and the hyperopic situations (p=0.09). Distance VA for the ATR, oblique, and WTR astigmatic situations was 0.01 ± 0.05, 0.01 ± 0.06, and 0.01 ± 0.04 logMAR, respectively. VA was better for the reference situation (p < 0.001) and no differences were found among the three astigmatic situations (p=0.21). Low residual defocus and mixed astigmatic errors, regardless of its orientation, seem to be tolerated by patients implanted with the studied EDoF IOL. This trial is registered with NCT05392998. Registered 26 May 2022-Retrospectively registered.

Changes in Vector Astigmatism After Superotemporal Versus Temporal Clear Corneal Incision Cataract Surgery.

To investigate vector and refractive astigmatism changes after superotemporal versus temporal clear corneal incision cataract surgery. Patients were diagnosed with age-related cataract with corneal astigmatism < 1.5 diopters (D) and were divided into two groups: superotemporal incision (R group) and temporal incision (L group). Uncorrected visual acuity, manifest refraction, corneal topography, anterior segment optical coherence tomography was performed pre- and six months postoperatively. Total ocular astigmatism, corneal astigmatism, vector of surgically induced corneal astigmatism (SICA), non-corneal ocular residual astigmatism (N-CORA), postoperative intraocular lens decentration and tilt were analyzed. Results: Thirty-eight subjects were included: 21, R group; 17, L group. After surgery, the N-CORA decreased significantly from 1.17±0.72 D to 0.73±0.47 D in all patients (P=0.001), 1.03±0.52 D to 0.70±0.40 D in the R group (P=0.005) and 1.35±0.90 D to 0.78±0.55 D in the L group (P=0.033). Significant differences between t:he R and L groups were found in the postoperative meridian of anterior corneal astigmatism (75.95±52.50 vs 116.79±47.29; P=0.017), total corneal astigmatism (51.65±42.75 vs 95.20±57.32; P=0.011), J45 change vector of SICA in the anterior cornea (-0.10±0.18 vs 0.00±0.11; P=0.048) and total cornea surface (-0.14±0.17 vs 0.03±0.12; P=0.001). Conclusion: The N-CORA decreased significantly after cataract surgery. Superotemporal and temporal incisions caused differences in the meridian components of oblique astigmatism in some patients but did not have a significant effect on the magnitude of corneal astigmatism.

Comparison of Visual and Refractive Outcome between Two Methods of Corneal Marking for Toric Implantable Collamer Lenses (TICL) in Phakic Eyes

Purpose To compare the efficacy of digital-assisted reference marking for toric implantable collamer lenses (Callisto Eye System) with manual marking technique using a slit lamp markeur. Methods This study included patients that underwent implantation of a toric implantable collamer lens (EVO Visian toric ICL, Staar Surgical). Patients were included if they had a myopia above −3 diopters (D) and regular corneal astigmatism of 0.75 diopters or higher. Between both groups a 1:2 matching regarding similar preoperative level of myopia and astigmatism was performed. Visual and refractive outcomes were evaluated. Vector analysis was performed to evaluate total astigmatic changes. Results This study comprised 57 eyes of 57 patients with 19 eyes in the digital group and 38 eyes in the manual marking group. Postoperatively there were no statistically significant differences between both groups in UDVA (p = 0.467), spherical equivalent (SE) (p = 0.864), sphere (p = 0.761) and cylinder (p = 0.878). Vector analysis showed a slightly more accurate postoperative refractive astigmatism in the manual group (0.26 D at 107° ± 0.50 D) compared to the digital marking group (0.31 D at 107° ± 0.45 D), nevertheless with no statistically significant differences between both groups. Conclusions A digital tracking approach for toric ICL alignment was an efficient and safe method for toric marking with similar results regarding visual and refractive outcomes compared to a conventional corneal marking method. Nevertheless, image-guided surgery helped to streamline the workflow in refractive ICL surgery.

Association of Maternal and Paternal Astigmatism With Child Astigmatism in the Hong Kong Children Eye Study

Parental astigmatism is a factor associated with risk for development of child astigmatism; however, the magnitude of the association has not been determined. To determine the association between parental and child astigmatism. This population-based, cross-sectional study included participants from familial trios, each comprising a child aged 6 to 8 years and both parents, recruited from the Hong Kong Children Eye Study. No restriction criteria were set on the children in terms of refractive status. Data were analyzed from February to June 2022. Cycloplegic autorefraction and autokeratometry were conducted on the children, whereas noncycloplegic autorefraction and autokeratometry were conducted on their parents. The children were categorized into 6 groups on the basis of the severity of astigmatism of both parents. Information on parental education, family income, and children's outdoor and near work time were obtained by questionnaires. The primary outcome was the odds of child astigmatism among the 6 categories of children. Associations of factors with child astigmatism were evaluated by logistic regression analyses. A total of 17 124 participants from 5708 trios (2964 boys and 2754 girls) at a mean (SD) age of 7.32 (0.87) years, and 11 416 parents were examined. Astigmatism of 1.0 D or greater in both parents was associated with greater odds of refractive astigmatism (RA) (odds ratio [OR], 1.62; 95% CI, 1.15-2.26) and corneal astigmatism (CA) (OR, 1.94; 95% CI, 1.50-2.50) in the child. The respective ORs increased to 3.10 (95% CI, 1.34-7.21) and 4.31 (95% CI, 1.76-10.55) when both parents had astigmatism 2.0 D or greater. Higher parental astigmatism conferred higher risks for both RA and CA in children (P for trend <.001). Parental astigmatism was significantly associated with greater odds of corresponding child astigmatism (maternal RA: OR, 0.76; 95% CI, 0.68-0.84; paternal RA: OR, 0.82; 95% CI, 0.74-0.91; maternal CA: OR, 1.70; 95% CI, 1.51-1.93; paternal CA: OR, 1.33; 95% CI, 1.19-1.49). The findings of this cross-sectional study suggest that parental astigmatism may confer an independent and dose-dependent association with child astigmatism. Children with parents with astigmatism should have early eye examinations for timely detection of astigmatism to facilitate age-appropriate vision correction and visual development.

Analysis of visual and refractive results after wedge resection for high astigmatism after penetrating keratoplasty in keratoconus.

To analyze visual and refractive results after wedge resection to correct high astigmatism after penetrating keratoplasty (PK) for keratoconus. Cornea Unit of the Centro de Oftalmología Barraquer Barcelona, Spain. A retrospective quasi-experimental, before and after study. Patients who developed high astigmatism or ectasia in the graft-host junction after PK were treated with wedge resection. The following variables were studied before the surgery, 1-year after and at the final visit: uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive and topographic astigmatism and spherical equivalent. Vectorial analysis of the astigmatism changes was performed. Fifty-one eyes were included with a mean follow-up of 4.19 ± 3.09 years. Mean refractive astigmatism was 11.47 ± 3.57 diopters (D) pre-operatively and 4.79 ± 3.32 D at the final follow-up (p < 0.001). The mean centroid changed from 2.65 ± 11.82 D at 23 degrees preoperatively to 0.35 ± 5.86 D at 127 degrees postoperatively. Concerning spherical equivalent, the mean preoperative value was -3.10 ± 4.15 D and the mean postoperative value was -1.55 ± 3.41 D (p = 0.002). Mean pre-operative and final follow-up UDVA were 1.25 ± 0.27 and 0.84 ± 0.50 (p < 0.001). Mean Pre-op and final follow-up CDVA were 0.27 ± 0.19 and 0.24 ± 0.24. Wedge resection is a useful surgical procedure to correct high astigmatism. It is a safe technique with moderate efficacy and may be considered as initial procedure of choice in high astigmatism due to long-term ectasia in the graft-host junction after PK for keratoconus.

Roles of Toric intraocular Lens implantation on visual acuity and astigmatism in glaucomatous eyes treated with iStent and cataract surgery

BackgroundTo assess the efficacy of toric intraocular lenses (IOLs) in combined cataract and minimally invasive glaucoma surgery (MIGS), visual and refractive outcomes were compared between eyes implanted with non-toric and toric IOLs during iStent triple procedures.MethodsIn this retrospective study, open angle glaucoma eyes with preexisting corneal astigmatism of -1.5 diopter (D) or more and implanted with non-toric (n = 9) or toric (n = 9) IOLs were included. The main outcome measures were the intergroup difference in the uncorrected visual acuity (UCVA) and refractive astigmatism at 3 months postoperatively.ResultsPreoperatively, the logarithm of the minimum angle of resolution (logMAR) UCVAs and refractive astigmatism were equivalent between the groups. Postoperatively, the logMAR UCVA (non-toric, 0.45 ± 0.31; toric, 0.14 ± 0.15; P = 0.021) was significantly better and the refractive astigmatism (non-toric, -2.03 ± 0.63 D; toric, -0.67 ± 0.53 D; P = 0.0014) significantly less in the toric group. The toric group had postoperative improvements in the logMAR UCVA (-0.21, P = 0.020) and refractive astigmatism (+ 1.72 D, P = 0.0039). Vector analyses showed the postoperative centroid magnitude and confidence eclipses of refractive astigmatism was less in the toric group (0.47 D at 173°±0.73D) than the non-toric group (1.10 D at 2°±1.91D). Postoperatively, 78% of eyes in the toric group had 1.0 D or less refractive astigmatism compared with 11% in the non-toric group. Surgically induced astigmatism (non-toric, 0.18 D at 65°; toric, 0.29 D at 137°) did not differ between groups.ConclusionUse of toric IOLs is a reasonable option for better visual outcomes when the combined cataract and iStent surgery is performed in glaucomatous eyes with corneal astigmatism.

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

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

Posterior Corneal Astigmatism Does Not Influence Manifest-Treated Topography-guided LASIK Outcomes

To investigate whether the magnitude of posterior corneal astigmatism (PCA) impacts refractive and visual outcomes of primary topography-guided laser in situ keratomileusis (LASIK) and to provide guidance on treating eyes with high PCA. Comparative retrospective analysis of 4,541 consecutive eyes treated with Contoura (Alcon Laboratories, Inc) on the manifest refractive astigmatism. Standard outcomes of the 1,514 eyes with the lowest PCA (first tercile; low PCA group) were compared to the 1,514 eyes with the highest PCA (last tercile; high PCA group). Pearson correlation coefficient was used to assess relationships between variables. Preoperatively, 20.9% of eyes presented with PCA of 0.50 diopters (D) or greater. The mean PCA was 0.18 ± 0.07 D in eyes with low PCA, and 0.50 ± 0.11 D in eyes with high PCA. An equivalent number of eyes achieved a cumulative postoperative unilateral uncorrected distance visual acuity of 20/20 in both the low PCA and high PCA groups (95.3% vs 94.7%; P = .4489). The efficacy index of both low and high PCA eyes was identical (0.99 ± 0.06 vs 0.99 ± 0.08; P = .3192), as was the safety index (1.00 ± 0.02 vs 1.00 ± 0.03; P = .0110). The magnitude of preoperative PCA was weakly correlated with postoperative refractive astigmatism (R = 0.1323), but not with postoperative defocus equivalent (R = -0.0414) or spherical equivalent (R = -0.0128). PCA does not negatively impact the outcomes of topography-guided LASIK targeting the manifest refraction, having identical accuracy, efficacy, and safety in eyes with both low and high PCA. There is no scientific basis to measure and consider PCA in topography-guided LASIK planning software or nomograms if the excimer laser treatment input targets the manifest refraction. [J Refract Surg. 2022;38(12):780-790.].

Changes in corneal diameter in myopic children during 18 months randomly assigned to orthokeratology lenses or single‐vision spectacles

AbstractPurpose: Orthokeratology lenses (OKL) have been shown to reduce axial length elongation in myopic children. OKL are costume fit, reverse geometry lenses. One of the parameters used to ensure lens fitting is the corneal diameter. The purpose of this study was to investigate changes in corneal diameter during 18 months in myopic children randomized to OKL or single‐vision spectacles (SVS).Methods: This study was an 18‐month 1:1 randomized, controlled trial of Danish myopic children aged 6–12 years with myopia ranging from 0.5 to 4.75 diopters (D) spherical component and refractive astigmatism ≤2.5 D. The intervention was orthokeratology lenses (OKL), while the control group received SVS. The outcome measure was corneal diameter (Pentacam HR, Oculus, Wetzlar, Germany).Results: A total of 37 right eyes were included, 23 (13 female) in the control group and 14 (9 female) in the intervention group. We found a significant change in corneal diameter in both the control group (difference in medians of 0.20 mm, p &lt; 0.001, Wilcoxon signed‐rank test) and the intervention group (difference in medians of 0.175 mm, p &lt; 0.001, Wilcoxon signed‐rank test). Furthermore, when comparing our 2 groups, we saw a significantly smaller increase in corneal diameter in the intervention group compared to the control group (difference in medians of 0.025 mm, p = 0.03, Mann–Whitney rank‐sum test).Conclusions: The corneal diameter significantly changes during 18 months in Danish children in both groups, however, the difference is significantly less during OKL treatment. The latter needs further clarification at this point. We can conclude, that to ensure correct OKL fitting in children close monitoring during OKL treatment is necessary.

Algorithms for decision on intrastromal ring segment implantation

AbstractSuccess in improving vision with intracorneal ring segment (ICRS) implantation for keratoconus depends on understanding the phenotype/pattern present in a particular cornea, the relative weight of the different aberrations (astigmatism, coma, spherical), the mechanism of action of the implants, and the possible modalities of implantation. The application of a particular nomogram makes sense only there has been a decision on the location of the implants relative to the selected landmarks (axis of refractive or topographic astigmatism, coma axis, etc.). It is possible to define all possible modalities of implantation of 1 or 2 ICRS based on only two features: whether there is implantation symmetry and the position of the center of the implant relative to one significant landmark (usually the flat topographic meridian) what we call “axiality”. The resulting matrix/classification includes 6 possible modalities. This presentation will develop on the author's methodology for ICRS selection based on this concept.

Intrastromal corneal ring segments implantation with the aid of a femtosecond laser in cases of mild to moderate keratoconus: A 3‐year study

AbstractPurpose: To evaluate the 3‐year results of femtosecond assisted intrastromal corneal ring segments (ICRS) implantation for the treatment of mild to moderate keratoconus.Methods: Prospective case series including 4 eyes of 4 consecutive patients with keratoconus.Each patient was implanted with ICRSs according to the preoperative topography and refraction. The segments were implanted in intracorneal pocket created with the FS200 femtosecond laser. Planning of the operation was done based on the nomograms provided by the manufacturer. Patients' follow‐up involved visual acuity measurement, refraction control, clinical examination, corneal topography (Pentacam and Orbscan) and anterior segment OCT. The operation was performed due to patients' unsatisfying spectacle corrected visual acuity and contact lens intolerance.Results: Preoperative average steep keratometry was reduced from 53,3D (range 50.7–55.7D) to 48.6D (range 46.9‐50D) 3 years postoperatively. Preoperative average topographic astigmatism was 5.35D (range 4.2–7.9D) while postoperative was 2.7D (range 0.7–4.3D). Refraction assessment showed reduction of the refractive astigmatism from 3.5D (range 2.0–5.0D) to 2,5D (range 0.5–3.75D) and improvement of spherical equivalent from −5.0D (range − 4.0 to −7.25D) preoperatively to −2.5D (range −1.25 to −3.25D) 3 years postoperatively. Average pre‐op spectacle corrected visual acuity was 4/10, when post‐op visual acuity assessment on Snellen scale showed average improvement by 2 lines (range from 0 to 5 lines).Conclusions: The femtosecond assisted ICRS implantation based on the results of our study, improved all patients' visual acuity, topographic and refractive parameters 3 years postoperatively.

Does Adjunctive Under-flap CXL Reduce Regression for Hyperopic LASIK?

To investigate whether adding accelerated under-flap corneal cross-linking to hyperopic laser in situ keratomileusis (LASIK-ufCXL) affects postoperative stability and regression, visual and refractive outcomes, and subjective quality of vision. This prospective comparative contralateral eye study included 51 patients with hyperopia (102 eyes) who received LASIK-ufCXL in the eye with highest defocus equivalent (DEQ) or randomized when DEQ equal, with the contralateral control eye receiving LASIK alone. After excimer ablation, 0.25% riboflavin was instilled on the stromal bed for 3 minutes. The flap was repositioned, followed by a total irradiation dose of 3.24 J ultraviolet A (UV-A) light administered to the corneal surface, using 18 mW/cm2 UV-A for 3 minutes. Postoperative hyperopic regression (stability) was the primary outcome measure, defined by the difference in spherical equivalent (SEQ) at 1 week and 24 months postoperatively. Secondary measures reported uncorrected distance visual acuity, corrected distance visual acuity, cylinder vector analysis, subjective quality of vision, subjective night vision disturbances, and corneal haze. At 24 months, the SEQ stability (P = .4273) and the magnitude of hyperopic regression (P = .5613) did not significantly differ between groups, with a small trend showing hyper-opic regression of 0.50 diopters or greater being less frequent in LASIK-ufCXL eyes. There were no significant differences in accuracy, efficacy, and safety (P > .05), with a small trend of more residual refractive astigmatism in the LASIK-ufCXL group (P = .3216, Cohen's d: -0.29). Subjective quality of vision trended inferior in LASIK-ufCXL eyes (P = .2237, Cohen's d: -0.25), with a greater haze grading (P = .0466, Cohen's d: 0.41). Postoperative regression and stability were statistically equivalent between hyperopic LASIK vs LASIK-ufCXL, with identical safety. There were small clinical trends of lower efficacy, accuracy, and subjective quality of vision in LASIK-ufCXL eyes. [J Refract Surg. 2022;38(12):770-779.].

Visual and Refractive Efficacy of Panoptix Toric Intraocular Lens in a Clinical Setting.

Trifocal Intraocular Lenses (IOLs) were developed to provide patients with effective near, intermediate and distance vision, thus minimizing spectacle dependency. Residual astigmatism has previously been shown to impact unaided visual acuity across all distances; therefore, to optimise the expected outcomes, consideration of preoperative corneal astigmatism is essential. The purpose of this study was to provide a real-world, multi-site review of visual and refractive outcomes in eyes undergoing implantation with the Panoptix Trifocal toric IOL platform. This study represents a two-fold approach. Patients who had previously undergone routine cataract removal and IOL insertion with the Panoptix Toric IOL were retrospectively analysed for routine efficacy and safety endpoints ("Retrospective Cohort"). Data was retrieved from the preoperative, surgical and postoperative visits (range 2-6 weeks). A further subset of patients undergoing lens removal and bilateral Panoptix Toric IOL insertion were identified at surgery ("Qualitative Cohort"). These patients underwent additional testing inclusive of quality of vision questionnaire and bilateral defocus curve. A total of 466 eyes of 254 patients were included in the retrospective cohort. Between 91% and 98% of eyes, respectively, were within 0.50D and 1.00D of target. Mean absolute difference from Spherical Equivalent (SE) target was 0.22 ± 0.24Ds. Following surgery, 94% of eyes demonstrated a refractive astigmatism of 0.50D or less. Further, 61% eyes achieved uncorrected distance visual acuity (UDVA) of 20/20 or better, increasing to 94% achieving 20/32 or better. Seventy percent of eyes unilaterally achieved N5 unaided and 66.0% achieved N8 or better at intermediate. In the qualitative cohort, no patient described any symptom as significant or requested explant. In a real-world setting, the PanOptix toric trifocal IOL continues to demonstrate refractive accuracy and good visual performance at all focal distances. This IOL also exhibited good quality of vision, with minimally bothersome visual disturbances or photic phenomena.

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.

Refractive outcomes following bilateral implantation of a diffractive toric intraocular lens in a multisurgeon hospital setting

ObjectifÉvaluer l’astigmatisme réfractif résiduel postopératoire après l'implantation bilatérale de lentilles intraoculaires (LIO) trifocales toriques dans un contexte réel où évoluent plusieurs chirurgiens. NatureÉtude prospective regroupant plusieurs chirurgiens (6 chirurgiens dans 2 établissements). MéthodesOn a procédé à l'implantation bilatérale de LIO trifocales toriques (LIO AcrySof PanOptix; Alcon Vision LLC, Fort Worth, Texas, États-Unis) dans 140 yeux de 70 patients. Les patients ont été évalués au jour 1 et 3 mois après l'intervention. Le principal paramètre de mesure consistait en la présence d'astigmatisme résiduel. Au nombre des paramètres secondaires, mentionnons l'erreur de prédiction absolue, la rotation des LIO, l'acuité visuelle binoculaire non corrigée, l'acuité visuelle corrigée de près (40 cm), à distance intermédiaire (60 cm) et de loin (6 m) de même que l'indépendance aux lunettes évaluée par un questionnaire validé de satisfaction envers les LIO. RésultatsLe cylindre préopératoire moyen se chiffrait à 1,25 ± 0,72 D pour atteindre 0,39 ± 0,28 D 3 mois après l'intervention. Lors de l’évaluation à 3 mois, l'astigmatisme résiduel moyen était de 0,39 ± 0,28 D (fourchette : 0–1,25 D); l'astigmatisme postopératoire s’élevait à 0,5 D ou moins dans 118 yeux (84,3 %). Pour sa part, l'erreur de prédiction absolue moyenne était de 0,25 ± 0,21 D (fourchette : 0–1,13 D); l'erreur de prédiction absolue se chiffrait à 0,5 D ou moins dans 124 yeux (88,6 %). La rotation moyenne absolue était de 2,0 ± 2,7 degrés, comparativement aux valeurs de départ (fourchette : 0–15 degrés); 133 LIO (95,0 %) se situaient à ≤ 5 degrés de l'axe d'implantation. Enfin, 55 patients (79 %) ont signalé ne jamais porter de lunettes ou affirmé ne les porter que rarement pour la vision de près, au même titre que 66 patients (94 %) pour la vision à distance intermédiaire et que 67 patients (96 %) pour la vision de loin. ConclusionsSi l'on en croit les résultats de notre étude, l'implantation de LIO toriques PanOptix peut donner d'excellents résultats réfractifs et visuels qui s'accompagnent d'un astigmatisme résiduel peu marqué.

One-dioptre toric IOL versus spherical IOL in eyes with low preoperative corneal astigmatism

PurposeTo investigate the advantages/disadvantages of a 1.0 D toric IOL vs spherical IOL after regular phacoemulsification in eyes with preoperative astigmatism ≤ 1 D.MethodsRetrospective comparative series involving pseudophakic eyes with preoperative topographic astigmatism ≤ 1.0 D implanted either with monofocal 1.0 D Toric IOL (T-group), or with spherical IOL (S-group). The postoperative refractive astigmatism (PRA, i.e. surgically induced + corneal) was the main outcome; also considered in the analyses were the uncorrected and best-corrected distance visual acuity (VA). The data were referred to the last postoperative follow-up visit, 2 to 4 months after surgery.ResultsA total of 60 eyes were included: 30 in the T-group and 30 in the S-group, matched for patient’s age, laterality, and axial length. Before surgery, the mean corneal astigmatism was 0.62 ± 0.39 D in the T-group and 0.54 ± 0.33 D in the S-group (p = 0.4). In the S-group, PRA was 0.73 ± 0.37 D, higher than the corresponding preoperative corneal astigmatism (p = 0.040). In the T-group, PRA was 0.58 ± 0.31 D; the variation was not statistically significant. Uncorrected VA was significantly better in the T-group vs the S-group (p = 0.007), and the best-corrected VA was comparable in the two groups.ConclusionThe present study indicated that in eyes with very low preoperative astigmatism, 1.0 D toric IOLs were able to limit the increase of the PRA instead of those observed with the spherical IOLs. This could support the better uncorrected VA recorded in the T-group.

Outcomes of Conventional 8.0-mm Versus Large 9.0-mm Diameter Deep Anterior Lamellar Keratoplasty for Keratoconus.

The purpose of the study was to compare the clinical outcomes of large 9.0-mm diameter and conventional 8.0-mm big-bubble deep anterior lamellar keratoplasty (DALK). In this comparative, retrospective interventional case series, medical records of 124 cases of large 9.0-mm diameter DALK from January 2017 to December 2019 and 133 conventional 8.0-mm DALK from January 2014 to December 2016 performed by a single surgeon for the indication of keratoconus were reviewed. Main outcome measures were best spectacle-corrected visual acuity (BSCVA), refractive astigmatism (RA), and postoperative complication rates. Postoperative logarithm of the minimum angle of resolution BSCVA did not significantly differ between 9.0-mm and 8.0-mm DALK at any time points. Although the cumulative percentage of eyes achieving Snellen BSCVA of 20/40 or better was comparable between groups (9.0-mm DALK: 93%, 8.0-mm DALK: 90%, P = 0.571), the cumulative percentage of eyes achieving 20/20 or better (9.0-mm DALK: 44%, 8.0-mm DALK: 26%, P = 0.01) and 20/25 or better (9.0-mm DALK: 74%, 8.0-mm DALK: 59%, P = 0.03) was significantly higher in the 9.0-mm DALK group. RA was significantly lower in the 9.0-mm DALK group compared with the 8.0-mm DALK group during all time points ( P < 0.001). The percentage of eyes with RA less than or equal to 4.0 D was significantly lower in the 9.0-mm DALK patients (90%) compared with in 8.0-mm DALK group (72%) ( P = 0.002). Postoperative complication rates were similar between groups. Compared with conventional 8.0-mm DALK, large 9.0-mm DALK can provide superior visual outcomes at higher levels of Snellen BSCVA and significantly lower degrees of astigmatism without an increased risk of immune rejection and graft failure.

A Modified Knotless Transscleral Intraocular Lens Fixation Technology for Congenital Ectopia Lentis.

This study aimed to compare modified knotless transscleral suture fixation of intraocular lens (IOL) with traditional transscleral suture fixation for adolescents and young patients with congenital ectopia lentis (CEL). This retrospective cohort study included 49 patients with CEL (60 eyes) who underwent surgery at the Zhongshan Ophthalmic Center. Improvements based on knotless Z-suture fixation technique were made to form a modified knotless method, in which thicker 8-0 polypropylene sutures were used, and double parallel scleral grooves were constructed behind the limbus instead of triangular lamellar scleral flaps to cover suture stitches. Modified knotless transscleral fixation of IOL was conducted on 30 eyes, and the other 30 eyes underwent traditional transscleral fixation surgery. Pre- and postoperative best-corrected visual acuity (BCVA), refractive error, astigmatism, other ocular parameters, and complications were statistically analyzed. For patients in the modified knotless group, the mean cylindrical refractive error and astigmatism at 1month and 3months postoperative were lower (all P < 0.05), and the mean IOL tilt degree was smaller at 3months postoperative (3.21° ± 2.13° vs. 5.65° ± 3.66°, P = 0.032). The incidence of suture exposure in the modified knotless group was also lower than in the controls (0 vs. 16.7%, P = 0.026). No group differences were observed in mean BCVA, spherical equivalent, or other ocular biometric parameters between groups. Modified knotless technique was a valid method to achieve optimal IOL position and reduce postoperative astigmatism for adolescents and young patients with CEL. It effectively reduced the incidence of knot-related complications, greatly improved the postoperative comfort, and achieved aesthetic benefits.

Age- and gender-related characteristics of astigmatism in a myopic population.

PurposeTo explore age- and gender-related differences of refractive and corneal astigmatism in myopic patients looking for refractive surgery.DesignA retrospective cross-sectional study.Materials and methodsThe medical files of candidates looking for corneal refractive surgery between 2019 and 2021 were reviewed, demographic and refractive parameters including age, gender, refractive status, and corneal parameters were analyzed.ResultsA total of 1,417 eyes of 1,417 patients (453 males and 964 females) were included. Males had thicker cornea than females, while females had steeper cornea than males, there was no gender-related difference in refractive and corneal astigmatism depending on patients’ age. There was no difference in refractive astigmatism among different age group from 18 to 50 years, while corneal astigmatism had a shift from with-the rule (WTR) to against-the-rule (ATR) with increasing age. Age, central corneal thickness (CCT), sphere, refractive astigmatism (RA), and corneal curvature (Km) were correlated with corneal astigmatism (CA) (standardized coefficients of are 0.006, p = 0.011 for age, −0.001, p = 0.004 for CCT, and −0.027, p < 0.001 for sphere, 0.61, p < 0.001 for RA, −0.05, p < 0.001 for corneal curvature).ConclusionRefractive astigmatism is stable until the age of 50 years in myopic patients looking for refractive surgery, while corneal astigmatism showed a shift from WTR to ATR with advancing age. Age, CCT, sphere, refractive astigmatism and corneal curvature (Km) were correlated with corneal astigmatism.