Refractive Astigmatism Research Articles

Topographical and functional analysis of different surgical strategies for advanced pellucid marginal degeneration: A long term follow-up.

To compare clinical and topographical outcomes of three different surgical strategies for advanced pellucid marginal degeneration (PMD). Retrospective, interventional case series of 8 advanced PMDs undergoing three different surgical interventions: Sliding Keratoplasty (SK), Sliding Keratoplasty with Relaxing Incision (SKRI), Sector Lamellar Keratoplasty (SLK). Pre-operatively and at 1, 3, 6, 12-month and final follow-up (50.8 ± 20.6 months) post-operatively, we collected: uncorrected and corrected distance visual acuity (UDVA and CDVA), spherical equivalent (SE), refractive astigmatism (RA), corneal Ks, topographical astigmatism (TA) and calculated against-the-rule (ATR) component. CDVA significantly improved from 6 months after surgery (p = 0.04), while final CDVA was at least 20/40 in 75% of eyes. As desired, surgery led to an overcorrection toward with-the-rule astigmatism at 1-month, which then decreased at 12-month and at final follow-up (p < 0.05). The ATR-component was significantly decreased at 1-month (1.9 ± 1.1 vs. 17.6 ± 6.3 D pre-operatively, p = 0.0015) and remained quite stable over time (4.2 ± 4.2 D at final follow-up). In subgroup analysis, SK and SKRI offered better CDVA and lower RA, while SLK showed more TA stability. The ATR component, comparing baseline and final follow-ups, decreased from 16.8 ± 8.3 D to 5.9 ± 3.6 after SK; from 18.9 ± 3.6 D to 3.3 ± 3.3 D after SKRI; from 17.0 ± 10.3 D to 1.9 ± 1.5 D after SLK. The surgical treatment of advanced PMD showed long-term favourable outcomes. SK and SKRI offered better visual outcomes, but were more inclined to astigmatism regression over time. Conversely, SLK had more stable results but offered worse refractive outcomes.

Ray-tracing-Guided or Q-Value-Adjusted FS-LASIK for Correction of Myopia and Myopic Astigmatism: A Comparative Contralateral Eye Study.

To compare the safety and efficacy of individualized ray-tracing-guided femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for correction of myopia and myopic astigmatism. This prospective, randomized, double-blind, contralateral eye study included 68 eyes of 34 patients with myopia or myopic astigmatism requiring FS-LASIK treatment. For each patient, one eye was randomly assigned to receive the ray-tracing-guided treatment, whereas the contralateral eye underwent Q-value-adjusted ablation. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), sphere, cylinder, effective optical zone (EOZ), and 6-mm corneal aberrations were measured and analyzed before operation and after a 3-month postoperative follow-up. At 3 months postoperatively, the UDVA of 20/16 or better was measured in 94% of eyes in the ray-tracing group and 85% of eyes in the Custom-Q group (P = .064). Forty-seven percent in the ray-tracing group and 32% in the Custom-Q group gained one or more Snellen lines of CDVA (P = .043). The MRSE, refractive astigmatism, surgically induced astigmatism, and difference vector were better in the Custom-Q group (P < .05). The postoperative corneal HOAs and optical path difference were significantly better in the ray-tracing group (P = .008). The EOZs of the ray-tracing and Custom-Q groups were 5.77 and 5.43 mm (P < .001), and the average ablation depths of the ray-tracing and Custom-Q groups were 100.97 and 85.24 µm (P < .001), respectively. Despite the overcorrection and excessive ablation of corneal tissue, ray-tracing-guided FS-LASIK in clinical practice was found to be safe and effective for myopic correction both with and without astigmatism, particularly in achieving UDVA and inducing fewer corneal HOAs and less OPD. [J Refract Surg. 2024;40(11):e804-e813.].

Factors predicting slow visual recovery following microkeratome-assisted myopic LASIK.

To identify factors predicting slow visual recovery following myopic microkeratome assisted insitu keratomileusis (LASIK). Retrospective study. This study included consecutive patients who underwent microkeratome-assisted myopic LASIK between January 2005 and December 2019 at Care Vision Laser Center, Tel Aviv, Israel. Patients were divided into three groups according to whether they experienced normal recovery of visual acuity (1 week visit), slow visual recovery (1 month visit) or very slow recovery (>1 month). Normal visual recovery was defined as achieving an efficacy index of 0.9 or greater. Efficacy index was calculated as postoperative uncorrected visual acuity/preoperative best corrected visual acuity. A comparison of baseline and intraoperative parameters was performed. Overall, 10 439 eyes were included. Mean age was 30.8 ± 8.7 years and 47.1% were females. The slower visual recovery groups (slow 11.4%, n = 1191; very slow 8.4%, n = 875) were of older age (p < 0.001), steeper preoperative steep keratometry (p = 0.002) and larger refractive astigmatism (p < 0.001). In binary logistic regression older age (p < 0.001), female gender (p = 0.001), larger astigmatism (p < 0.001) and high myopia (p < 0.001) remained significant predictors of slow visual recovery. Slow visual recovery was observed in 19.8% of patients following myopic LASIK. Older age, female gender, larger astigmatism and high myopia were associated with slow visual recovery. Patients may be advised accordingly.

Factors Predicting Slow Visual Recovery Following Myopic Photorefractive Keratectomy.

To identify factors predicting slow visual recovery following photorefractive keratectomy (PRK). This retrospective study included consecutive patients who underwent PRK between January 2005 and December 2019 at Care Vision Laser Center, Tel Aviv, Israel. Myopic patients were divided into 2 groups according to whether they experienced normal recovery of visual acuity (within 60 days) or slow visual recovery (>60 days). Visual recovery was defined as achieving an efficacy index of 0.9 or greater. Efficacy index was calculated as postoperative uncorrected visual acuity/preoperative best corrected visual acuity. A comparison of baseline and intraoperative parameters was performed. Binary logistic regression was performed to identify potential predictors of slow visual recovery. Overall, 4868 eyes were included. The mean age was 25.9 ± 7.7 years, and 53.9% were male. The slow visual recovery group (39.3%, n = 1911/4868) was older (P < 0.001) and had greater refractive astigmatism (P < 0.001) with a larger proportion of recent contact lens wearers (P = 0.002). The slow recovery group had larger optic zone treatments (P < 0.001), alcohol-assisted PRK (vs. transepithelial PRK) (P < 0.001), and greater maximum ablation depth (P < 0.001). In binary logistic regression, older age (P < 0.001), higher refractive astigmatism (P = 0.01), recent contact lens wear (P = 0.01), greater optic zone treatment (P = 0.001), and alcohol-assisted PRK (P < 0.001) remained significant predictors of slow visual recovery. Slow visual recovery was observed in ∼40% of patients following myopic PRK. Older age, greater refractive astigmatism, recent contact lens wear, greater optic zone treatment, and alcohol-assisted PRK were associated with slow visual recovery.

Clinical Outcomes of Modified Manual Deep Anterior Lamellar Keratoplasty for Eyes with Previous Radial Keratotomy.

Background: The aim of this study was to evaluate the intraoperative complications and visual outcomes of manual deep anterior lamellar keratoplasty (mDALK) in patients who underwent previous radial keratotomy (RK) for myopia. Methods: The notes of patients who underwent mDALK after RK at three different hospitals-San Giovanni Addolorata Hospital (Rome, Italy), Mount Saint Joseph Hospital (Vancouver, Canada), and Tor Vergata University Hospital (Rome, Italy)-were retrospectively reviewed. We analyzed the manual dissection success rate and conversion to penetrating keratoplasty (PK), the residual recipient stromal thickness, the postoperative corrected distance visual acuity (CDVA), postoperative refraction, and topographic astigmatism. Results: Thirteen eyes of eleven patients were included in the analysis (male 7/11, 63.6%). Preoperatively, mean topographic astigmatism was 5.4 ± 3.5 D (range 1.6-14.8 D), and mean CDVA was 0.47 ± 0.2 logMAR (range 0.3-1.0 logMAR) [Snellen equivalent 20/50]. Manual dissection was performed in all cases. None of the examined eyes were converted to PK. An improvement in both topographic astigmatism (2.8 ± 0.9 D, p = 0.0135) and CDVA (0.23 ± 0.2 LogMAR, p = 0.0122) was recorded at 12-month follow-up. Conclusions: mDALK is a safe and effective surgical technique when applied to eyes previously treated with RK, with an observed improvement in CDVA and topographic astigmatism.

Functional outcomes and quality of life after AcrySof IQ Vivity intraocular lens implantation in a real-world study

The extended depth-of-focus AcrySof IQ Vivity intraocular lens technology offers promising features for presbyopia management, evaluated in this research in a 6 months real-world setting. Prospective interventional mono-centric study including 40 patients who underwent elective bilateral phacoemulsification. We performed one pre-operative visit (V0) and one evaluation six months post-operatively (V1), evaluating uncorrected and corrected visual acuity for near (UNVA/CNVA), intermediate (UIVA/CIVA) and far (UDVA/UCVA), slit-lamp evaluation, tomography with static pupillometry, endothelial cell count and contrast sensitivity chart. In order to assess post-operative Quality of Life, we administered the patients McAlinden’s Quality of Vision test and Morlock’s Patient-Reported Spectacle Independence Questionnaire. We divided eyes in with Toric-IOL and with non-Toric IOL. A total of 36 eyes received non-tonic IOL implantation, whereas 44 eyes received toric IOL implantation. There were no statistically significant disparities observed in visual outcome measures and contrast sensitivity between the toric group and the non-toric group. Furthermore, we assessed the predictive preoperative refractive astigmatism (PPRA) and residual refractive astigmatism (RRA) in both cohorts, and no statistical significance was found between the two cohorts (p = 0.08). Twenty-one (53%) patients reported total independence from their glasses at all distances. The mean difference between the predicted and measured refractive error, as calculated by spherical equivalent, was 0.09 D. AcrySof IQ Vivity is a well-tolerated and effective IOL with optimal refractive target for both distant and intermediate vision, needing slight spherical addition for the best near vision. Great questionnaire-based satisfaction was reported by the patients.

Comparison of visual efficacy and patient’s satisfaction between two toric IOLs, enhanced for intermediate vision and monofocal

BackgroundTo compare the visual efficacy and patient satisfaction between 2 toric IOLs (TIOL), enhanced for intermediate vision or monofocal.MethodsA retrospective chart review was performed of 100 eyes from 68 astigmatic patients who underwent cataract surgery with implantation of a Tecnis Eyhance Toric II IOL (Johnson & Johnson Vision, Irvine, CA, USA) (Group 1, 50 eyes) or Tecnis TIOL (Group 2, 50 eyes). The uncorrected distant (UDVA), intermediate (UIVA), and near (UNVA) visual acuities; residual refractive astigmatism; defocus curve; and IOL axis rotation were evaluated at 1 week, 1 month, 2 months, and 3 months postoperatively.ResultsThe postoperative UDVA and UNVA refractive astigmatism values of the two groups were better than the preoperative measurements (P < 0.05), but there was no statistical difference between the two groups (P > 0.05). The postoperative UIVA of group 1 (0.18 ± 0.15 logMAR) was significantly better than that of group 2 (0.30 ± 0.25) (P < 0.05). The mean postoperative IOL rotation of group 1 (2.51 ± 0.79°) was lower than that of group 2 (3.02 ± 0.84°) (P < 0.05). Overall satisfaction of group 1 (1.27 ± 0.47) was better than that of group 2 (2.02 ± 0.53) (P < 0.05).ConclusionsThe Tecnis Eyhance Toric II IOL demonstrated less postoperative IOL rotation and excellent uncorrected intermediate vision compared with the Tecnis TIOL. Near visual acuity and overall satisfaction with the Tecnis Eyhance Toric II IOL were also higher than those with the Tecnis TIOL.

Epidemiology of eye diseases in Bangladesh

Bangladesh is densely populated country in South Asia, faces significant challenges in eye health due to various socioeconomic, environmental, and healthcare access factors. Limited access to quality eye care services, poor hygiene practices, prevalence of infectious diseases, and a high burden of non-communicable diseases contribute to the prevalence of eye disorders in the region. This study aims to comprehensively analyze the prevalence, distribution, and risk factors associated with various eye diseases among the population of Bangladesh. A systematic review and meta-analysis were conducted to gather data on the epidemiology of eye diseases in Bangladesh. Published studies, national surveys, and reports from relevant health organizations were reviewed to compile data on the prevalence, distribution, and risk factors of common eye conditions, including cataracts, refractive errors, conjunctivitis, glaucoma, diabetic retinopathy, and age-related macular degeneration. The prevalence of eye diseases in Bangladesh is relatively high, with conditions such as refractive errors, cataracts, glaucoma, and corneal diseases being major concerns. Refractive errors, including myopia, hyperopia, and astigmatism, affect a substantial portion of the population, particularly among children and young adults. Cataracts, a leading cause of blindness worldwide, also pose a significant burden in Bangladesh, with prevalence increasing with age. While the prevalence of glaucoma in Bangladesh is lower compared to some other countries, the condition remains a cause of concern due to its impact on quality of life and the healthcare system. Diabetic retinopathy, a complication of diabetes mellitus, affects the retina and is a leading cause of vision loss and blindness globally in the elderly. In Bangladesh, the rising prevalence of diabetes, fueled by changing lifestyles and an aging population, has contributed to an increasing burden of diabetic retinopathy. Conjunctivitis is prevalent, particularly in densely populated urban areas and rural communities with limited access to clean water and sanitation facilities.Collaborative efforts involving government agencies, healthcare providers, non-governmental organizations, and the community are essential to effectively address the burden of eye diseases in Bangladesh. By implementing preventive measures and improving access to quality eye care services, it is possible to mitigate the impact of these eye diseases and improve visual health outcomes for the population.

Clinical outcomes after topography-guided FS-LASIK for myopia with nonastigmatic eyes

BackgroundTo analyze the clinical outcomes after topography-guided femtosecond laser–assisted laser in situ keratomileusis (FS-LASIK) with Phorcides Analytic Engine (PAE) algorithm or Custom-Q FS-LASIK for myopia with nonastigmatic eyes.MethodsIn this retrospective study, a total of 90 eyes with myopia without manifest astigmatism (82 patients) were included. All surgeries were performed by topography-guided FS-LASIK planned with a PAE algorithm (42 eyes) or Custom-Q system (48 eyes). Refractive, visual outcomes and corneal aberrations were compared between the two groups.ResultsAt 6 months postoperatively, the postoperative uncorrected distance visual acuity (UDVA) was 20/20 or better in 42 eyes (100%) in the PAE compared with 44 eyes (92%) in Custom-Q (P = .120). The postoperative UDVA of 20/16 or better was measured in 92% of eyes in the PAE group and 81% of eyes in the Custom Q group (P = .320). Postoperative corrected distance visual acuity, manifest refractive spherical equivalent and refractive astigmatism were similar between the two groups (P > .05). The postoperative optical path difference (OPD) and Strehl ratio (SR) were significantly better in the PAE group compared with the Custom Q group.ConclusionsTopography-guided FS-LASIK with PAE algorithm or Custom Q demonstrated similar refractive efficacy and predictability. PAE for the patients with zero manifest astigmatism demonstrated better results in correcting corneal aberrations.

Evaluating the small aperture intraocular lens: depth of focus and the role of refraction and preoperative corneal astigmatism in visual performance.

To evaluate depth of focus (DOF) and visual acuities (VAs) by manifest refractive spherical equivalent (MRSE) and degree of preoperative corneal astigmatism with the IC-8 small aperture intraocular lens (SA IOL) (Apthera). 21 investigational sites in the United States. Prospective, multicenter, open-label, parallel-group, nonrandomized, examiner-masked, 1-year clinical study. Included patients had cataract and ≤1.5 diopters (D) preoperative corneal astigmatism. Patients received either the SA IOL in 1 eye targeted to -0.75 D and a monofocal or monofocal toric IOL in the other targeted to plano (SA IOL group) or bilateral monofocal/monofocal toric IOLs targeted to plano (control group). Monocular and binocular assessments included defocus curves and uncorrected VAs (distance, intermediate, and near) by postoperative MRSE; monocular VAs were assessed by degree of preoperative corneal astigmatism. The SA IOL group (n = 343) achieved 0.82 D additional binocular DOF vs the control group (n = 110), and SA IOL eyes achieved 0.91 D additional monocular DOF over fellow eyes. Across all MRSEs, the SA IOL group achieved monocular uncorrected VAs of 20/40 or better and binocular uncorrected VAs of 20/32 or better across all distances. In addition, SA IOL eyes with higher (1.0-1.5 D) vs lower (<1.0 D) preoperative corneal astigmatism achieved equivalent monocular uncorrected VAs. The SA IOL provides increased DOF vs monofocal/monofocal toric IOLs and consistent monocular and binocular vision across several postoperative MRSEs and up to 1.5 D of preoperative corneal astigmatism, giving patients with cataract and mild astigmatism the potential for an extended range of vision and reliable visual outcomes.

Refractive outcomes after V4c Toric collamer lens implantation over 1y of follow-up.

To evaluate refractive outcomes and corneal astigmatism changes after Toric implantable collamer lens with a central port (V4c T-ICL) implantation over 1y of follow-up. A retrospective study was performed including 50 eyes of 50 patients that underwent V4c T-ICL implantation. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, refractive and corneal astigmatism changes and corneal coupling correction were evaluated preoperatively, 1 and 12mo postoperatively. Vector analysis was used for astigmatism changes. Coefficient of adjustment (CAdj) was calculated for corneal coupling analysis. The mean UDVA achieved was 0.03 logMAR at 1mo and remained unchanged throughout the whole follow-up (P=0.193). At the last visit, 84% of the eyes achieved a CDVA of 0.00 logMAR or better. Regarding spherical equivalent refraction (SEQ), 96% of eyes were ranges of ±1.00 D and 84% of them within ±0.50 D. Also, 94% of eyes had a remaining refractive cylinder within ±1.00 D and 78% of them within ±0.50 D. Both, SEQ and refractive cylinder, remain stable over the postoperative follow-up (P=1.000 and P=0.660, respectively). In terms of surgically induced astigmatism (SIA), no statistically significant differences were found over the follow-up (P=0.102) and under correction was found with a correction index lower than the unit at each visit. A keratometric astigmatism induced of 0.59±0.53 (vector mean: 0.26×73°) D was reached at the last visit. No significant changes in terms of corneal astigmatism orientation were reported over post-surgery visits (P=0.129 and P=0.097 at 1 and 12mo respectively). No clinical significance was found for CAdj on with-the-rule astigmatism. No postoperative complications resulting from the surgery were found. Refractive outcomes suggest that the V4c T-ICL implantation for correction of myopic astigmatism was satisfactory in terms of effectiveness, safety, and stability during 1y of follow-up. Corneal astigmatism induced by the incision around 0.5 D is achieved according to the remaining refractive cylinder found at one-year post-surgery. Corneal coupling analysis results in no unexpected spherical change.

Rotational stability and refractive outcomes of a new hydrophobic acrylic toric intraocular lens

PurposeTo assess rotational stability and refractive outcomes of a new toric hydrophobic acrylic intraocular lens (IOL).DesignSingle-center, prospective, interventional clinical trial.MethodsA total of 130 eyes of 82 patients with age-related cataract and total corneal astigmatism of greater than 1.0 diopters (D) received a hydrophobic acrylic toric IOL Clareon CNW0T3-9. Baseline measurement for rotational stability evaluation was performed at the end of surgery (EOS), with the patient still supine on the operating table, using non-movable vessels as reference landmarks. Postoperative retroillumination pictures were taken at 1 h, 1 week, 1 month and 4–6 months postoperatively. Subjective manifest refraction was assessed at the 6 months follow-up visit.ResultsFinal results were obtained in 126 eyes of 80 patients. Mean absolute rotation from EOS to 6 months was 1.33 ± 2.00 [0.01, 19.80] degrees. Rotational stability values from EOS to 1 h, 1 h to 1 week, 1 week to 1 month and 1 month to 6 months were 0.86 ± 0.82 [0.00, 3.90], 1.06 ± 1.94 [0.00, 19.45], 0.47 ± 0.42 [0.00, 2.03] and 0.38 ± 0.40 [0.00, 2.56] degrees. Mean preoperative corneal astigmatism was 1.78 ± 0.83 [1.00, 4.76] D which changed to a mean postoperative refractive astigmatism of 0.33 ± 0.27 [0.00, 1.25] D at 6 months.ConclusionThe Clareon toric IOL presented very good rotational stability with a mean absolute rotation below 1.4° from EOS to 6 months. Only two IOLs rotated more than 5° with none of them requiring repositioning surgery. Refractive outcomes were satisfying with a mean residual refractive astigmatism below 0.50 D.Trial registrationRegistered at Clinicaltrials.gov NCT03803852; on May 17, 2022.

A New Methodology for Evaluating the Potential Impact of Residual Refractive Astigmatism in Pseudophakic Patients.

To validate a new methodology to evaluate the impact of astigmatism in pseudophakia using an astigmatic defocus curve. Hospital Oftalmológico de Brasilia, Brazil. Non-randomized cohort study. For every point of the defocus curve, from -2.00 to +3.00 with 0.50D intervals, visual acuity was assessed with optically induced astigmatism (0.50D, 1.00D and 1.50D at 90 and 180 degrees) in pseudophakic patients implanted with a refractive-enhanced intraocular lens. Twelve patients were analyzed. A statistically significant difference was found between the 90° (ATR) and 180°(WTR) axis with 1.50D astigmatism, providing better visual acuity in ATR astigmatism (p < 0.05). This new methodology is reproducible, useful and may predict residual astigmatism tolerance in pseudophakic patients, which may help with surgery planning and IOL decision-making.

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.].

Vector Planning: Treating Asymmetrically and Achieving the Minimum Refractive and Regular Corneal Astigmatism

Vector Planning: Treating Asymmetrically and Achieving the Minimum Refractive and Regular Corneal Astigmatism

Relation between change of effective lens position and toric IOL rotation after toric IOL implantation

PurposeTo evaluate the relationship between change of effective lens position (ELP) and toric intraocular lens (IOL) rotation in patients with increasing postoperative refractive astigmatism after successful toric IOL implantation. MethodsThe subjects include 61 people (61 eyes) with increasing residual astigmatism >0.5 D 3 months after successful toric IOL implantation. Clinical measurements included preoperative, 1-week, and 1-, 2-, and 3-month postoperative visual acuity; refraction; keratometer; anterior and posterior corneal astigmatism; ELP by Scheimpflug camera imaging; and IOL axis by slit-lamp biomicroscopic photograph with pupil dilation. ResultsResidual astigmatism in postoperative month 3 (0.81 ± 0.50 D) is higher than that at postoperative week 1 (0.41 ± 0.38 D; p < 0.05). ELP decreased by 264.44 ± 163.25 μm, and the IOL rotated by 2.91 ± 1.44 degrees from week 1 to month 3 (p < 0.05). The ELP change had a positive correlation with IOL rotation (R2 = 0.383; p = 0.006), and the postoperative refractive astigmatic change had a positive correlation with ELP change (R2 = 0.272; p = 0.027) and IOL rotation (R2 = 0.272; p = 0.0001) from week 1 to month 3. ConclusionELP change can influence toric IOL rotation and increase residual astigmatism after toric IOL implantation.

Refractive Errors of School Children from Economically Disadvantaged Areas in Northwest México.

Background: Refractive errors, including myopia, hyperopia, and astigmatism, are the leading causes of visual impairment in school-aged children and can significantly impact their academic performance and quality of life. This study aimed to assess the prevalence of refractive errors among school children from economically disadvantaged areas in Northwest México, using a consistent methodology to facilitate comparison with global data. Methods: We adopted the Refractive Error Study in Children (RESC) protocol by the World Health Organization to examine the prevalence of myopia, hyperopia, and astigmatism. The study comprised a systematic sampling of children aged 6 to 18 years from diverse schools in Northwest México. Trained optometrists conducted visual acuity testing and autorefraction, while ophthalmologists performed cycloplegic refraction to ensure accuracy. Results: The study found a myopia (SE ≤-1.50 D at least one eye) prevalence of 14.55% (95% CI: 13.27-15.91), with a higher incidence in females (6.92%) compared to males (6.00%) in at least one eye. Hyperopia (SE ≥ +1.00 D at least one eye) was less common, at 3.23% (95% CI: 2.61-3.95), with a slightly higher occurrence in males in at least one eye. Astigmatism (Cylinder ≥ 0.75 D at least one eye) was present in 18.63% (95% CI: 17.21-20.12) of the students in at least one eye, with no significant difference between genders. These findings are consistent with other studies in regions such as Puerto Rico and Iran, indicating widespread refractive error issues among schoolchildren. Conclusions: The high prevalence of refractive errors, particularly myopia and astigmatism, highlights the critical need for regular vision screenings in schools and the implementation of public health interventions to provide corrective eyewear. Our study confirms the importance of utilizing standardized methodologies like the RESC protocol to compare refractive error prevalence across different geographical and socio-economic contexts, thereby informing global public health strategies.

Refractive Astigmatism Outcomes of Femtosecond Laser-Assisted Arcuate Keratotomies Combined with Femtosecond Laser-Assisted Cataract Surgery: Two-Year Results

Purpose To evaluate the effectiveness and stability of refractive astigmatism reduction after penetrating femtosecond laser-assisted arcuate keratotomy performed at the time of femtosecond laser-assisted cataract surgery. Methods Non-randomized retrospective data analysis of all patients that underwent femtosecond laser-assisted cataract surgery with femtosecond laser-assisted arcuate keratotomy over a 4-year period with a non-toric monofocal intraocular lens (2017–2021) at a tertiary care academic center. Postoperative visual acuity, manifest refraction, and predicted residual refractive error were also recorded at 1 month, 3–6 months, 12–18 months, and 2 years postoperatively. Preoperative keratometric astigmatism was compared to postoperative refractive astigmatism using vector calculations and the ASCRS double-angle plot tool. Results This study comprised 266 eyes (179 patients) that met inclusion criteria. The mean preoperative keratometric astigmatism magnitude was 0.99 ± 0.53 D. At 1 month, 3–6 months, 12–18 months, and 2 years postoperatively, the mean refractive cylinder was 0.49 ± 0.45 D, 0.49 ± 0.45 D, 0.55 ± 0.54 D, and 0.52 ± 0.46 D, respectively. Horizontal against-the-rule astigmatism showed a higher tendency toward undercorrection than vertical with-the-rule astigmatism, which had a slightly higher tendency toward overcorrection. With-the-rule astigmatism had smaller difference vectors between target-induced astigmatism and surgically induced astigmatism. Conclusions Femtosecond laser-assisted arcuate keratotomy performed at the time of femtosecond laser-assisted cataract surgery was an effective option for correcting low-to-moderate corneal astigmatism for up to 2 years.

Prevalence of visual impairment and estimation of refractive errors among school children in Kakamega, Kenya.

To investigate the prevalence of visual impairment (VI) and provide an estimation of uncorrected refractive errors in school-aged children, conducted by optometry students as a community service. The study was cross-sectional. Totally 3343 participants were included in the study. The initial examination involved assessing the uncorrected distance visual acuity (UDVA) and visual acuity (VA) while using a +2.00 D lens. The inclusion criteria for a subsequent comprehensive cycloplegic eye examination, performed by an optometrist, were as follows: a UDVA<0.6 decimal (0.20 logMAR) and/or a VA with +2.00 D ≥0.8 decimal (0.96 logMAR). The sample had a mean age of 10.92±2.13y (range 4 to 17y), and 51.3% of the children were female (n=1715). The majority of the children (89.7%) fell within the age range of 8 to 14y. Among the ethnic groups, the highest representation was from the Luhya group (60.6%) followed by Luo (20.4%). Mean logMAR UDVA choosing the best eye for each student was 0.29±0.17 (range 1.70 to 0.22). Out of the total, 246 participants (7.4%) had a full eye examination. The estimated prevalence of myopia (defined as spherical equivalent ≤-0.5 D) was found to be 1.45% of the total sample. While around 0.18% of the total sample had hyperopia value exceeding +1.75 D. Refractive astigmatism (cil<-0.75 D) was found in 0.21% (7/3343) of the children. The VI prevalence was 1.26% of the total sample. Among our cases of VI, 76.2% could be attributed to uncorrected refractive error. Amblyopia was detected in 0.66% (22/3343) of the screened children. There was no statistically significant correlation observed between age or gender and refractive values. The primary cause of VI is determined to be uncorrected refractive errors, with myopia being the most prevalent refractive error observed. These findings underscore the significance of early identification and correction of refractive errors in school-aged children as a means to alleviate the impact of VI.

Accuracy of Toric Intraocular Lens Formulas With Measured Posterior Corneal Astigmatism of Different Orientations

PurposeTo assess whether the use of measured posterior corneal astigmatism (PCA) values improves the prediction accuracy of toric intraocular lens power formulas, compared to predicted PCA values, when the orientation of the steep axis of PCA is non-vertical. DesignRetrospective observational cohort study Methods418 eyes of 344 patients were included in the study. Prediction errors (PE) for postoperative refractive astigmatism at 4 weeks postoperatively were determined using vector analysis and compared for the following toric intraocular lens power formulas: Barrett Toric with predicted posterior corneal astigmatism (PPCA); Barrett Toric with measured posterior corneal astigmatism (MPCA); EVO Toric PPCA; EVO Toric MPCA; Holladay I with Abulafia-Koch regression. Subgroup analysis compared PEs for eyes with a vertically orientated steep axis of PCA (60-120o) to eyes with a non-vertically orientated steep axis of PCA. SettingCathedral Eye Clinic, Belfast, United Kingdom and Tan Tock Seng Hospital, Singapoore. ResultsStandard keratometry was with-the-rule in 48% of eyes, while the steep PCA axis was vertically orientated in 91% of eyes. For all eyes, EVO PPCA had a smaller mean absolute error than Barrett-MPCA, Barrett-PPCA and Abulafia-Koch (p < 0.01 for all). EVO-PPCA had the highest percentage of eyes within 0.50D of predicted postoperative astigmatism for eyes with vertical PCA (61%), while EVO-MPCA had the highest percentage for eyes with non-vertical PCA (54%). EVO-MPCA had the smallest centroid error for all eyes, and the subgroups (p < 0.01 for all). Eyes with non-vertical PCA had a lower percentage within 0.50D than eyes with vertical PCA when using PPCA (43% vs 61%, p = 0.034), but there was no significant difference between these groups when MPCA is used for eyes with non-vertical PCA (54% vs 61%, p = 0.40). ConclusionsWhen the steep axis of posterior corneal astigmatism is not vertically orientated, the use of measured posterior keratometry values improves prediction accuracy.