High Astigmatism Research Articles

Prevalence of Refractive Errors and Associated Factors in the Population of the Eye Cohort Study in Southeast Iran

Objectives: The study aims to determine the age- and sex-adjusted prevalence of refractive errors and its related factors among the adult population of southeastern Iran. Methods: The current study included 9280 individuals aged 35 to 70 years using a multistage random sample method from October 2015 to January 2019 as a part of a Persian cohort study in Zahedan. Uncorrected and corrected vision, objective noncycloplegic, and subjective refraction were measured, with all participants undergoing ophthalmoscopy, slit-lamp biomicroscopy, fundoscopy, refraction, and retinoscopy. Data were analyzed using SPSS version 23.0 statistic software and described as percentage, odds ratio, and 95% confidence interval. Comparisons between groups and relationships among risk factors and refractive errors were performed with chi-square, nominal, and multiple regression analysis. Results: The prevalence of low and moderate myopia, high myopia, low and moderate hyperopia, high hyperopia, low and moderate astigmatism, and high astigmatism was 24.2 (95% CI: 22.40 - 25.90), 1.5(95% CI: 0.00 - 3.53), 16.1(95% CI: 14.20 - 17.90), 1.3(95% CI: 0.00 - 3.30), 35.6 (95% CI: 33.90 - 37.30), and 3.8 (95% CI: 1.80 - 5.70) percent, respectively. The prevalence of refractive errors significantly varied across different age groups overall and by sex (P = 0.01). The proportion of refractive errors also significantly differed by education (P = < 0.001). The prevalence of against the rule, with the rule, and oblique astigmatism was 32.8 % (95% CI: 31.10 - 34.20), 42.1% (40.50 - 43.60), and 24.9% (23.10 - 26.60), respectively. The risk of astigmatism was significantly lower in men than in women (OR = 0.75; 95 % CI: 0.60 - 0.90). Based on multiple regression, the risk of myopia (OR = 2.07; 95 % CI: 1.60 - 2.60) and hyperopia (OR = 25.38; 95 % CI: 18.70 - 34.3) was higher in the age group 65 to 75 years compared to the younger group. Conclusions: The present study provided valuable information on the prevalence of refractive errors in the adult population in south-eastern Iran. The findings underscore the need for comprehensive eye care services, particularly for older individuals and those with lower education levels. Further prospective research is warranted to explore the factors contributing to refractive errors and to develop effective strategies for its prevention and management.

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

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

Children with high astigmatism: tomographic and refractive characteristics and the ability of current indices to rule out keratoconus

PurposeTo assess corneal tomographic, topographic, and refractive changes in children with high astigmatism and their ability to exclude keratoconus. MethodsIn this longitudinal observational study, the medical records of children with high regular cylindrical refraction of ≥3.50 D referred to the Hospital for Sick Children, Toronto, to exclude keratoconus between January 2009 and June 2020 were reviewed retrospectively. Corneal tomography records (Scheimpflug imaging) were reviewed for subjects with total astigmatism of ≥ +3.50 D by retinoscopy. Children with abnormal anterior segment examination and/or other risk factors for corneal disease or ectasia and those with unreliable corneal tomography were excluded. Baseline demographic, longitudinal tomographic, topographic, and refractive data were analyzed. ResultsA total of 67 eyes of 37 children (mean age, 9.1 ± 3.5 years) were included. Mean cylindrical refraction at presentation was 5.10 ± 1.30 D. Mean follow-up was 2.3 ± 1.8 years. Twenty-nine eyes had Kmax ≥47.20 D at baseline, with no change at last follow-up. Ksteep, Kmax, and thinnest pachymetry were 46.44 ± 2.33 D, 47.06 ± 2.57 D, and 525.86 ± 35.45 μm, respectively, at baseline compared with 46.40 ± 2.28 D, 46.98 ± 2.40 D, and 527.61 ± 37.67 μm at last follow-up (P > 0.05). All eyes were predicted as not having keratoconus using inferior-superior dioptric asymmetry ratio (I-S ratio), and the keratometry, inferior-superior, and astigmatism index (KISA%), which also incorporates skew percentage. The other tomographic indices predicted keratoconus or subclinical keratoconus in at least 22.4% of eyes. All parameters did not significantly change during follow-up. ConclusionsIn the absence of other risk factors for keratoconus, children with high regular astigmatism demonstrated clinical and tomographic stability over time. Based on our results, we recommend that I-S ratio and KISA% be primarily used when monitoring normal children with high astigmatism to rule out keratoconus-related changes.

Retracted: Clinical Study on the Differential Diagnosis of High Myopia Astigmatism and Subclinical Keratoconus in Adolescents by Pentacam Anterior Segment Analyzer.

[This retracts the article DOI: 10.1155/2022/6370791.].

Comparison of different methods of correcting astigmatism in cataract surgery

ABSTRACT Clinical relevance Astigmatism causes a decrement in visual acuity, and deterioration in visual quality. Background The aim of this study is to compare clear corneal incision (CCI) in the steepest meridian, opposed clear corneal incision (OCCI) and toric intraocular lens implantation methods for the correction of astigmatism in cataract surgery. Methods Total of 93 preoperative patients with the rule corneal astigmatism (between 1.00–3.00 D)underwent uncomplicated cataract surgery are retrospectively included in this study. Whole patients are divided into three groups of equal number of patients of 31 by considering the astigmatism correcting methods that are as follows. Group 1 consists of patients underwent CCI on the steepest meridian, group 2 consists of the patients underwent paired OCCI, and group 3 consists of those with toric intraocular lens implantation. The preoperative and postoperative 3rd month uncorrected distance visual acuity, refraction and, keratometry values, and surgically induced astigmatism values calculated by Alpins method are recorded. Results The age, preoperative and postoperative 3rd month spherical, spherical equivalent refraction and keratometry values of the groups are similar (p > 0.05). The preoperative uncorrected distance visual acuity values are similar in whole groups, postoperative uncorrected distance visual acuity values are the highest in group 1, and lowest in group 3 (p = 0.85, p = 0.02, respectively). The preoperative and postoperative 3rd month mean cylinder refraction values are -1.86 D, -1.00 D in group 1, −1.77 D, -0.70 D in group 2, and −1.95 D, -0.40 D in group 3. There is a statistically significant difference among the groups (p = 0.01). The surgically induced astigmatism values are statistically different among the groups [it was 0.46 ± 0.21 in group 1, 0.91 ± 0.44 in group 2, 0.33 ± 0.18 in group 3 (p < 0.001, respectively)]. Conclusion This study indicated that; CCI, paired OCCI, and toric intraocular lens implantation should be preferred and performed for the steepest meridian in low D, middle D, and high D astigmatism patients, respectively. CCI can easily be applied for low to medium D without needing extra skills and tools. On the other hand, toric intraocular lens implantation is a better option for a high astigmatism with proper and accurate planning before the surgery.

Systematic ophthalmologic evaluation in cardio-facio-cutaneous syndrome: A genotype-endophenotype correlation.

Cardio-facio-cutaneous syndrome (CFCS) is a rare genetic disorder belonging to the RASopathies, a group of developmental syndromes caused by upregulated RAS/MAPK signaling. Pathogenic variants affecting four genes, KRAS, BRAF, MAP2K1 and MAP2K2, encoding core signal transducers of the pathway, underlie the condition. Major clinical features include a distinctive facies, ectodermal and cardiac anomalies, reduced postnatal growth, intellectual disability, and musculoskeletal abnormalities. Similar to other RASopathies, reports of visual impairment, high refractive error, optic nerve pallor, and other ocular abnormalities have been anecdotally reported in the literature. The aim of our study is to report the prevalence of ophthalmologic abnormalities in a large monocentric cohort of individuals affected by CFCS and explore the occurrence of genotype-endophenotype correlations in this series of patients. We observed that BRAF mutations are associated to a higher prevalence of anisometropia >3D (11.8% vs. 0%) and high astigmatism (29.4% vs. 0%; both p < 0.001) while patients with mutations in other genes had a significantly higher prevalence of myopia >6 D (60% vs. 5.9%; p = 0.012). Pale optic disc was associated with higher prevalence of inferior oblique muscle (IO) overaction (33.3% vs. 0%) and lower prevalence of ptosis (0% vs. 11.8%; both p < 0.001). Combined exotropia, IO overaction and nystagmus were frequent in patients with pale optic nerve. Our findings might suggest the need for earlier ophthalmologic referral for CFCS patients due to high risk of amblyopia, especially those expressing BRAF mutations.

Keratoconus Diagnosis and Treatment: Recent Advances and Future Directions.

Keratoconus is a disorder characterized by progressive corneal thinning and steepening that may result in significant visual impairment secondary to high astigmatism, corneal scarring, or even corneal perforation. Early detection and screening of keratoconus are essential for effective management and treatment. Several screening methods, such as corneal topography and tomography, corneal biomechanics, and genetic testing, are being developed to detect keratoconus at an early stage. Once detected, prevention of progression is the mainstay of keratoconus management. Corneal collagen cross-linking is a minimally invasive treatment option that can slow or halt the progression of keratoconus. Additionally, recent studies have investigated the potential use of copper sulfate eye drops (IVMED-80) and extracellular vesicles to prevent the progression of keratoconus as non-invasive treatment options. For visual rehabilitation, currently available treatments include scleral lenses, intracorneal ring segments, corneal allogenic intrastromal ring segments, and deep anterior lamellar keratoplasty. The safety and efficacy of these emerging treatment options for keratoconus are currently being investigated.

MANAGEMENT OF IRREGULAR ASTIGMATISM AFTER CORNEAL ULCER WITH RGP CONTACT LENS IN PATIENTS WITH HIGH MYOPIA

Introduction: RGP contact lenses are indicated for correcting refractive errors in cases of high myopia and irregular astigmatism due to changes in the corneal curvature. Case Report: A 30-year-old female came with complaints of redness, pain, glare, blurred vision, and yellow discharge and tearing on the left eye for 2 days, history of using Soft Contact Lens (SCL) since 10 years old due to myopia. Visual Acuity of the right eye (VOD) with glasses was 6/12 and VA of the left eye (VOS) was 1/300. The patient was diagnosed with left eye corneal ulcer and was given levofloxacin eye drops, hydroxypropyl methylcellulose eye drops, and vitamin C 1000 mg. The left eye's corneal ulcer healed after three days, but the scarring left the cornea's surface uneven.. Patients were advised to replace the contact lenses with RGP contact lenses. After the RGP fitting, the appropriate size was obtained in both eyes and the patient adapted well with VOD RGP 1.0 and VOS RGP 1.0 False. The patient felt helped by the RGP contact lens. Discussion: RGP was given because it helped reduce the bacterial infection risk. RGP has a higher oxygen transmissibility and maintains the cornea's curvature to become more regular. It can be utilized as an optical device to repair excessive myopia in addition to irregular astigmatism. Conclusion: RGP contact lens can be an option for irregular astigmatism after corneal ulcers due to the SCL use in patients with high myopia to provide good outcomes.

Refractive Accuracy and Visual Outcome by Self-Refraction Using Adjustable-Focus Spectacles in Young Children

Uncorrected refractive error is the most common cause of vision impairment in children. Most children 12 years or older can achieve visual acuity (VA) of 20/25 or better by self-refraction using adjustable-focus spectacles, but data on younger children are lacking. To assess refractive accuracy, corrected VA, and factors associated with not achieving VA of 20/25 or better among children aged 5 to 11 years performing self-refraction with Adspecs adjustable-focus spectacles (Adaptive Eyecare), compared with noncycloplegic autorefraction and cycloplegic refraction. This was a cross-sectional noninferiority trial conducted from September 2, 2015, to December 14, 2017. The study setting was an academic pediatric eye clinic. Children aged 5 to 11 years with uncorrected VA of 20/40 or worse in 1 or both eyes and without systemic or ocular conditions preventing best-corrected VA of 20/25 or better were enrolled. Children who had best-corrected VA worse than 20/25 were excluded. Study data were analyzed from September 2017 to June 2023. Children were taught to self-refract with adjustable-focus spectacles. Spherical equivalent refractive error (using self-refraction, noncycloplegic autorefraction, and cycloplegic refraction) and VA (uncorrected and using self-refraction, noncycloplegic autorefraction, and cycloplegic refraction) for study eyes were evaluated. Potential predictors of failure to achieve VA of 20/25 or better with self-refraction were assessed using logistic regression. A total of 127 consecutive children were enrolled. After exclusions, 112 children (median [IQR] age, 9.0 [8.0-10.3] years; 52 boys [46.4%]) were included in the study. Mean (SD) spherical equivalent refractive power was -2.00 (1.52) diopters (D) for self-refraction, -2.32 (1.43) D for noncycloplegic autorefraction, and -1.67 (1.49) D for cycloplegic refraction. Mean (SD) difference in refractive power between self-refraction and noncycloplegic autorefraction was 0.32 (1.11) D (97.5% 1-sided CI, 0.11 to ∞ D; P < .001) and between self-refraction and cycloplegic refraction was -0.33 (1.15) D (97.5% 1-sided CI, -0.54 to ∞ D; P = .77). The proportion of children with corrected VA of 20/25 or better was 79.5% (89 of 112) with self-refraction, 85.7% (96 of 112) with noncycloplegic autorefraction, and 79.5% (89 of 112) with cycloplegic refraction (self-refraction vs noncycloplegic autorefraction: McNemar P value = .27; self-refraction vs cycloplegic refraction: McNemar P value > .99). Those failing to achieve best-corrected VA of 20/25 or better with self-refraction had higher astigmatism (odds ratio [OR], 10.6; 95% CI, 3.1-36.4; P < .001) and younger age (OR, 1.5; 95% CI, 1.1-2.2; P = .02). Self-refraction among children aged 5 to 11 years may result in more myopic power than cycloplegic refraction but not necessarily to a clinically relevant degree. Although the proportion of children achieving VA of 20/25 or better with self-refraction using adjustable-focus spectacles did not differ from cycloplegic refraction, it was less likely among younger children and those with higher astigmatism.

One-year clinical efficacy evaluation of selective corneal wavefront aberration-guided FS-LASIK correction in patients with high myopia.

To evaluate the effectiveness, safety, predictability, precision and changes of higher-order aberrations (HOAs) on corneal front surface of selective corneal wavefront aberration-guided femtosecond laser-assisted in situ keratomileusis (CW-FS-LASIK) in patients with high myopia 1-year postoperatively. Totally 74 eyes of 37 patients with high myopia or myopic astigmatism in both the eyes who underwent the CW-FS-LASIK procedure in Xi'an Gaoxin Hospital from January 2021 to June 2021 were included. The changes of uncorrected distance visual acuity (UDVA), best corrected visual acuity (BCVA), spherical equivalent refraction (SER), astigmatism, HOAs and Strehl ratio (SR) on the anterior surface of the cornea after 1y of the surgery were analyzed. At postoperative 1y, the UDVA (logMAR) of 74 eyes (100%) reached 0 or better, including 0 in 8 eyes (10.81%), -0.1 in 45 eyes (60.81%), and -0.2 in 21 eyes (28.38%). The effectiveness index was 1.29±0.134. There was no decrease in postoperative BCVA compared with preoperative BCVA in all patients. Postoperative BCVA was the same in 44 eyes (59.46%) as preoperative BCVA, increased by 1 line in 23 eyes (31.08%) and increased by 2 lines in 7 eyes (9.46%) compared with preoperative BCVA. The safety index was 1.11±0.159. The estimated corrected SER before surgery was (-7.76±1.21) D, and the actual corrected SER was (-7.83±1.25) D (Y=0.9811X+0.2156, R2=0.9084). There was a high correlation between the estimated corrected SER and the actual corrected SER. The postoperative SER in 74 eyes (100%) was within ±0.75 D. The postoperative astigmatism of all was within -0.75 D to 0. Root mean square (RMS) HOAs of spherical aberration and SR within 5 mm of the corneal front surface were all increased compared with those before operation (P<0.01). The total coma, horizontal coma and vertical coma were all decreased compared with those before operation (P<0.01). There was no statistically significant difference in horizontal trefoil and vertical trefoil compared with preoperative ones (P>0.05). Selective CW-FS-LASIK for correction of high myopia is effective, safe, predictive, and accurate. For patients with preoperative RMS HOAs over 0.25 defocus equivalent, postoperative coma aberration can be significantly reduced, and SR value can be increased, thus corneal imaging quality can be improved.

High Astigmatism Secondary to Peripheral Ectasia Recurrence in Postpenetrating Keratoplasty Eyes Managed With Miniscleral Contact Lenses.

After penetrating keratoplasty (PK) for keratoconus, vision can be impaired by high-degree astigmatism, particularly in those patients with recurrent peripheral ectasia. Scleral contact lenses (CLs) have long been used in the management of keratoconus both in treatment-naive corneas and those postcorneal transplants. We report the use of miniscleral CLs and their related visual and clinical outcomes in a series of patients with post-PK peripheral rim ectasia. In this retrospective case series, 5 patients (7 eyes) presented because of reduced visual acuity with their spectacles/CLs and/or reduced comfort with their existing rigid gas-permeable lenses. All patients in this series underwent PK more than two decades ago for keratoconus (mean 28.7 years±7.2). All patients demonstrated characteristic thinning at the graft-host junction, with anterior chamber deepening. Central corneas had remained clear in all patients inferring high visual potential. Contact lenses used were No 7 Comfort 15 miniscleral and the Onefit MED scleral with 14.5 mm and 15.6 mm diameters, respectively. All eyes achieved a best-corrected visual acuity of 6/9 or greater. One case had difficulty with insertion and removal and has since discontinued wearing lens at this time. All others are successfully wearing the lenses regularly. Despite advances in CL design, surgical management is still required in some patients. Miniscleral CLs are effective in the refractive management of peripheral ectasia in keratoconic post-PK eyes and should be considered in such eyes before proceeding with repeat surgical intervention.

Revisiting Javal's rule: a fresh and improved power vector approach according to age.

The scientific community has established Javal's rule as a model linking refractive (RA) and keratometric (KA) astigmatism since its appearance more than 100 years ago. The aim was to improve the accuracy of this relationship according to subject's age by applying the power vector analysis. Posterior corneal curvature has also been studied. The IOLMaster 700 optical biometer was used to measure the corneal thickness and the radius of curvature of the anterior and posterior corneal surfaces. Refractive error was determined by a non-cycloplegic subjective refraction process with trial lenses. Linear regression analyses were applied using J0 and J45 power vector components. An evaluation was carried out according to the subject's age resulting into eight regression relationships for each astigmatic vector component for each relationship. A total of 2254 right eyes from 2254 healthy subjects were evaluated. A trend towards against-the-rule astigmatism (ATR) was found with aging, both for refractive astigmatism (RA) and keratometric astigmatism (KA), with 95.2% of subjects under 20 years old having with-the-rule (WTR) KA, and only 22.8% above 79 years old. The following regression equations were found between RA and KA: [Formula: see text] = 0.73 × [Formula: see text] - 0.18 (R = 0.78) and [Formula: see text] = 0.70 × [Formula: see text] + 0.04 (R = 0.69) and between RA and total corneal astigmatism (TCA): [Formula: see text] = 0.73 × [Formula: see text] + 0.13 (R=0.78) and [Formula: see text] = 0.70 × [Formula: see text] - 0.06 (R = 0.68) for the whole sample, but with sensible differences among age groups, both in the slope and in the intercept. Ignoring the age of the subject when using Javal's rule could lead to an error in the final cylinder calculation that would increase in high astigmatisms. Applying this new power vector approach based on subject's age could improve the accuracy of the astigmatism prediction.

Spherical Aberration of Astigmatic Corneas in a Cataract Population.

To study the distribution of spherical aberration (SA) in astigmatic corneas in a cataract population and the relationship between magnitude of corneal astigmatism and fourth-order corneal SA. Data routinely collected using a Scheimpflug camera (Pentacam; Oculus Optikgeräte GmbH) were retrospectively analyzed. Patients with a minimum age of 60 years were included. Total corneal SA (from anterior and posterior corneal surface) was obtained for a 6-mm cor-neal area aligned with the pupil center. Exclusion criteria were insufficient measurement quality, total deviation index (Belin/Ambrósio Deviation) greater than 1.60, and corneal thickness at the thinnest point of less than 490 μm. One eye per patient was chosen randomly. Eyes were divided into low (≤ 1.00 diopters [D]), moderate (> 1.00 to ≤ 2.00 D), and high (> 2.00 D) astigmatism groups according to the Scheimpflug measurements. A total of 528 eyes were included in this analysis. Low astigmatism was found in 129 patients, moderate astigmatism in 265 patients, and high astigmatism in 134 patients. Mean astigmatism was 0.68 ± 0.24, 1.45 ± 0.28, and 2.91 ± 0.95 D in the low, moderate, and high astigmatism groups, respectively. Mean corneal SA in patients with moderate and high astigmatism was higher than in the low astigmatism group. The difference reached the significance level for the comparison of low and high astigmatism groups (P = .023). The fourth-order SA increased gradually with the magnitude of astigmatism with a slope of 0.015. SA was significantly larger in the cataract population with high corneal astigmatism. The increase of positive sign SA with the magnitude of astigmatism suggests that patients with moderate to high astigmatism may benefit more from intraocular lenses with negative sign SA correction. [J Refract Surg. 2023;39(8):532-538.].

Refractive outcomes of toric intra-ocular lens implantation in cases of high posterior corneal astigmatism.

To evaluate whether the toric intra-ocular lens (IOL) power calculation based on total corneal astigmatism (TCA) in eyes with high posterior corneal astigmatism (PCA) could result in a systematic over-correction or under-correction after operation. The present study included a mono-centric retrospective study design. The data were collected from 62 consecutive eyes during uncomplicated cataract surgery by a single surgeon with a measured PCA of 0.50 diopters (D) or higher. Toric IOL calculations were made using TCA measurements. The eyes were grouped as either "with-the-rule" (WTR) or "against-the-rule" (ATR) on the basis of the steep anterior corneal meridian. The post-operative refractive astigmatic prediction error was analyzed 1 month post-operatively using the vector analysis by the Alpins method and double-angle plots method. The correction indexes were 1.14 ± 0.29 in the ATR eyes and 1.25 ± 0.18 for the WTR eyes, indicating a tendency toward over-correction. The mean over-correction was 0.22 ± 0.52D in the ATR group and 0.65 ± 0.60D in the WTR group. The magnitude of error (ME) values were significantly different from the ideal value of zero in both groups (ATR: P = 0.03; WTR: P = 0.00). No significant difference in mean absolute error (MAE) in predicted residual astigmatism was found between ATR and WTR groups (0.61 ± 0.42 D versus 0.64 ± 0.39 D; P = 0.54). The ATR group yielded better results, with 48% <0.50D prediction error in the main analysis. The results suggested that in cases of high PCA, the toric IOL calculation, which was performed using TCA, may cause a potential over-correction in the ATR and WTR eyes. For ATR eyes, over-correction led to slight disruption of post-operative visual quality because of the "with-the-rule" residual astigmatism after operation. Therefore, we suggested using TCA for toric IOL calculation in ATR eyes.

Vector analysis of astigmatism correction after PRK, FS-LASIK, and SMILE for myopic astigmatism.

To compare astigmatic correction among photorefractive keratectomy (PRK), femtosecond laser-assistedin situkeratomileusis(FS-LASIK), and small-incision lenticule extraction (SMILE). This prospective study enrolled 157 eyes that underwent three procedures (59 PRK, 47 FS-LASIK, and 51 SMILE) for the treatment of myopia with low to high astigmatism (- 0.25 to - 4.50 D). Ocular residual astigmatism (ORA) was calculated by vector analysis using refractive (RA) and corneal astigmatism. Vector analysis results were compared in different procedures in the two RA groups (low ≤ 1.00 D and high > 1.00 D) at 3 and 12months postoperatively. There were no significant between-group differences in postoperative safety and efficacy outcomes (all P > 0.05). No significant differences were found in postoperative cylinders between all surgical groups (all p > 0.05), except for 3months postoperative ORA in FS-LASIK (P = 0.004). At 12months, 77%, 59.2%, and 50% of eyes attainemmetropia in the FS-LASIK, SMILE, and PRK groups, respectively. Vector analysis showed comparable values for surgical induced astigmatism, target induced astigmatism, mean error, and angle of error between groups at 12months. Significant differences were observed only in the correction index and difference vector parameters in the astigmatic > 1.00 D group at 3months (P < 0.001), and FS-LASIK was preferable. One-year outcomes revealed that PRK, FS-LASIK, and SMILE were all equally effective in correcting myopic astigmatism. However, FS-LASIK demonstrated more favorable astigmatism correction in eyes with astigmatism > 1.00D in early postoperatively.

Prevalence of refractive errors in population aged 50 years and over: The Gilan eye study.

To describe the prevalence of refractive error (RE) and its association with other environmental and health factors among population aged ≥50 years who lived in Gilan, Iran in 2014. In this population-based cross-sectional study, 3281 individuals aged ≥50 years living in Gilan for at least 6 months were enrolled. The prevalence of different types of REs including myopia (spherical equivalent (SE)≤-0.50D), high myopia (SE ≤ -6.00D), hyperopia (SE≥ + 0.50D), high hyperopia (SE≥ + 3.00D), astigmatism (cylinder < -0.50D) and high astigmatism (cylinder < -2.25D) were determined. Anisometropia was defined as the SE difference of ≥1.00D between the two eyes. Associated factors including age, body mass index (BMI) and education were also studied. 2587 eligible individuals (58% female subjects) with the mean age of 62.6 ± 8.8 years participated (87.6% response rate). The prevalence of myopia, hyperopia and astigmatism was 19.2%, 48.6% and 57.4%, respectively. 3.6% high hyperopia, 0.5% high myopia and 4.5% high astigmatism were identified. The positive simultaneous effects3 of older age (Odds Ratio (OR) = 3.14), nuclear (OR = 1.71) and posterior subcapsular (OR = 1.61) cataracts as well as the negative effects of higher levels of education (OR = 0.28) were obtained on myopia. Higher BMI was found as a risk factor for hyperopia (OR = 1.67), while older patients were less likely to be hyperopic (OR = 0.31). Higher incidence of myopia and astigmatism was found in patients aged over 70 years. It was also found that patients at older ages who suffered with cataracts were at a higher risk of myopia, while elderly people with greater BMI were at a higher risk of hyperopia.

Keratoconic patient profile and management at public sector facilities in South Africa

Background: Keratoconus (KC) is a condition marked by thinning and protrusion of the cornea resulting in high myopia and irregular astigmatism. Knowledge of KC patients’ profiles and management approaches used can help to predict the needs of public hospitals to improve patient care.Aim: This study aimed to describe the profiles and management of KC patients.Setting: Capricorn district, Limpopo Province, South Africa.Methods: Medical records of 188 KC patients attending public hospitals of Capricorn District from January 2017 to December 2020 were reviewed. Data on patient profile and their management were collected and analysed.Results: The mean age of KC patients was 20.64 ± 6.82 years and the majority (56.9%) were males. Clinical findings were mean unaided visual acuity (UVA) of 0.19 ± 0.18, best corrected VA of 0.53 ± 0.24, spherical equivalence of -4.89 ± 9.17 dioptre (D), mean K of 57.37 ± 17 D and corneal astigmatism of -6.24 ± 4.27 D. A total of 54.5% of patients had severe KC. Bilateral KC was found in almost all patients (97.3%) and a mean K difference of 7.59 ± 6.08 D (p 0.001) between the better and the worse eye. The study found no significant difference in KC severity by age (p = 0.451) and gender (p = 0.819). Patients fitted with scleral lenses had the highest VA improvement of 0.44 ± 0.17.Conclusion: Most patients presented with bilateral and severe KC. Scleral lenses provided higher VA improvement than other methods.Contribution: The study aimed to present the clinical profile and management of keratoconic patients attending public sector facilities. Knowledge of the patterns of KC presentation may assist in the development of intervention strategies and guidelines for best practice in the management of KC, especially in public sector facilities.

Factors Predictive of Refractive Error After Toric Lens Implantation.

To identify factors related to suboptimal refractive outcomes after toric intraocular lens implantation. A retrospective case-control chart review of 446 eyes with toric lens insertion by the same surgeon at a university hospital from 2016 to 2020 was conducted. Pre-operative exam findings, biometry, and one month and three month post-operative vision and refraction were noted. Reviewed charts were considered cases if uncorrected distance visual acuity (UDVA) was worse than 20/40, spherical equivalent (SE) >1 diopter (D) off target, or cylinder >1 D off target. Overall, 93.7% (n = 343) of eyes achieved UDVA of 20/40 or better, 92.7% (n = 306) were within 1 D of target SE, and 90.9% (n = 300) were within 1 D of target cylinder. UDVA cases had more eyes with prior LASIK (21.7% vs 7.0%, p = 0.01) and keratoconus (8.7% vs 0.6%, p < 0.001) than controls. More SE cases had prior radial keratotomy (RK) (8.3% vs 0%, p < 0.001) and keratoconus (12.5% vs 0%, p < 0.001) than controls. More cylinder cases had prior LASIK (30.0% vs 8.7%, p < 0.001) and higher mean astigmatism (2.3 vs 1.5 D, p = 0.02) than controls. More cases in all three analyses had higher toric cylinder power (T5-T9) than controls. Age, sex, eye laterality, axial length, anterior chamber depth, lens power, dry eye, anterior basement membrane dystrophy, and Fuchs' endothelial dystrophy differences were not significant. Prior LASIK or RK, keratoconus, and higher astigmatism may increase the chance of a suboptimal outcome.

Presumed Unindicated Implantation of Posterior Chamber Phakic Intraocular Lens.

BACKGROUND Refractive surgery is one of the most frequently performed ocular surgeries worldwide. Implantation of the posterior chamber phakic intraocular lens has advantages over laser vision correction, especially in high refractive error cases. We present a case of a young adult women with poor vision who underwent bilateral posterior chamber phakic intraocular lens explantation due to high vault, shallow anterior chambers, and a picture of cone-rod dystrophy. CASE REPORT A 23-year-old woman was referred for poor vision following an implantation of bilateral toric implantable collamer lens (ICL) implantation when she was 18 years old for high myopic astigmatism and anisometropia. On presentation, the best corrected visual acuity was 4-6/200 and 2-3/200 in the right eye and left eye, respectively. Slit lamp examination indicated a clear cornea with pigment deposition on the endothelium, high ICL vault, shallow anterior chamber, and bowing of the iris bilaterally. The patient underwent bilateral removal of the ICLs on separate visits, yet the vision remained unchanged. Diagnostics revealed that the patient had bull's eye maculopathy with atrophy due to her cone-rod dystrophy, which caused the poor vision. CONCLUSIONS This report emphasizes the need for careful and appropriate patient and intraocular size selection for refractive surgery. It indicates the importance of thorough medical examination, including genetic testing, fundus examination, and optical coherence tomography when retinal dystrophy is suspected. Generally, close follow-up is crucial in the setting of high vaulting following ICL implantation to prevent secondary complications.

Visual Acuity after Posterior Capsular Rupture during Cataract Surgery

Posterior capsular rupture (PCR) is a common and serious complication of cataract surgery. It complicates the process of inserting posterior chamber intraocular lens and affects the visual outcome. This study is a review on visual acuity of patients that had PCR during cataract surgery in Hospital Melaka, risk factors of PCR, and factors that cause poor visual outcome. The record of all patients that had PCR during cataract surgery from 1 January 2014 till 31 March 2017 was traced using National Eye Database (NED) and the patients’ folders were reviewed retrospectively. Data collected was demographic data, type of cataract surgery, status of surgeon, underlying ocular diseases, risks factors for PCR, postoperative visual acuity, and factors that cause poor visual outcome. There were 238 eyes that had PCR during cataract surgery, from 126 (53%) female and 112 (47%) male patients. The mean age was 66.62 years old, ranging from 9 to 87 years old. Major risk factors identified were hard cataract, polar cataract, uncooperative patients, extended continuous capsulorhexis, subluxated lens, myopia, vitrectomised eyes, and poor pupil dilatation. From 153 cases that had no pre-existing ocular diseases, 119 (78%) cases had normal vision (best corrected visual acuity – BCVA) two months after surgery, 10 (7%) cases had moderate visual impairment, and four (2%) cases had severe visual impairment. Causes of BCVA poorer than 6/18 were high astigmatism, CMO, and prolonged inflammation. Cataract surgery, even complicated by PCR, is compatible with good visual outcome if the complications are managed promptly.