Mean Spherical Equivalent Refraction Research Articles

Prism adaptation response and surgical outcomes of acquired nonaccommodative comitant esotropia

ABSTRACT Purpose To investigate the clinical factors influencing the prism adaptation response of acquired non-accommodative comitant esotropia (ANAET) and evaluate the surgical outcomes. Study design Retrospective observational study. Methods This study assessed patients with ANAET who underwent strabismus surgery based on the results of a short prism adaptation test (PAT). Patients wore Fresnel trial prisms based on alternate prism cover tests in outpatient clinics. The cover test was then performed after 15–20 minutes; if the deviation increased, the power of the prism was increased to neutralize the angle. The test was repeated until the angle was stable. Patients were classified as either prism builders (angle increased by ≥ 10 prism diopters [PD] compared with the entry angle) or prism non-builders (angle increased by < 10 PD). The following clinical characteristics were noted: age at onset, age at surgery, duration of esotropia, refractive error, angle of deviation, presence or absence of intermittent esotropia at near, and pre- and postoperative sensory status. Results A total of 41 patients (median age, 15.4 years) were evaluated. The mean (standard deviation) spherical equivalent refractions were −3.03 (3.33) diopters (D) and −3.05 (3.23) D in the right and left eyes, respectively. Twenty-seven (66%) patients were prism builders. The prism builders had greater myopia (builders vs. non- builders, right eye: −3.97 [2.97] vs. −1.22 [3.33] D, P = .01; left eye: −4.08 [2.78] vs. −1.07 [3.20] D; P = .003), lower angle of deviation at near (median [interquartile range] 30.0 [20.0, 35.0] vs. 42.5 [35.0, 49.4] PD; P = .009), much more preoperative intermittent esotropia or esophoria at near (44% vs. 7%, P = .03) and diplopia (96% vs. 64%, P = .01), and better postoperative stereoacuity (50 [40, 110] vs. 100 [60, 400] arcsec, P = .02) than the prism non-builders. The overall success rate was 83%, without a significant difference between the two groups (builders vs. non-builders, 89% vs. 71%, P = .21). Conclusion In cases of myopic refractive error, a small entry angle with intermittency at near, and good binocularity, it is recommended that surgery is performed based on prism-adapted angle to prevent under-correction.

Changes in retinal vascular bifurcation in eyes with myopia

ObjectiveTo evaluate the effect of myopia on retinal vascular bifurcation.MethodsA cross-sectional study that retrospectively analyzed the fundus photographs and clinical data of 493 people who participated in routine physical examinations in Huadong Sanatorium. One eye of each subject was included in the analysis. Retinal vascular bifurcation measurements were extracted by using a validated computer program. One-way ANOVA and analysis of covariance were performed to compare the measurements across high myopia, low to moderate myopia, and non-myopia groups.ResultsThe mean age was 41.83 ± 10.43 years and 63.49% were women. The mean spherical equivalent refraction (SER) was − 4.59 ± 3.07 D. Ninety-nine (20.08%) eyes met the definition of high myopia (SER ≤ -6.0 D), along with 234 (47.46%) low to moderate myopia (-6.0 D < SER <-0.5 D), and 160 (32.45%) non-myopia (SER ≥ -0.5 D). The differences in the arteriolar branching angle, venular branching coefficient, venular asymmetry ratio, venular angular asymmetry, and venular junctional exponent among the three groups remained significant (p < 0.05) after multivariate adjustment. Pairwise comparisons showed arteriolar branching angle and venular angular asymmetry in high myopia were significantly lower than low to moderate myopia (p < 0.001, p = 0.014 respectively) and non-myopia (p = 0.007, p = 0.048 respectively). Venular asymmetry ratio and venular branching coefficient in high myopia were significantly higher than low to moderate myopia (p = 0.029, p = 0.001 respectively) and non-myopia (p = 0.041, p = 0.043 respectively). There was a significant difference in venular junctional exponent between high myopia and low to moderate myopia (p = 0.031).ConclusionThe vascular bifurcation differs in dependence on the myopic refractive error and a significant increase in the difference can be observed in high myopic eyes.

Normative Data of Macular Thickness Using Spectral Domain Optical Coherence Tomography for Healthy Jordanian Children.

PurposeTo report normative values of macular thickness and volume by spectral-domain optical coherence tomography (SD-OCT) in the eyes of healthy Jordanian children aged 6–16 years and assess the correlation of macular parameters with age, sex, and refractive error.Patients and MethodsThis observational study included 144 eyes of 144 healthy children. All children underwent comprehensive ocular examination and cycloplegic refraction. Average macular thickness, macular volume, central subfield thickness (CST), and macular thickness for all the Early Treatment Diabetic Retinopathy Study (ETDRS) quadrants were obtained using Primus SD-OCT (Carl Zeiss Meditec).ResultsThe study group consisted of 68 boys and 76 girls with a mean age (SD) of 10.8 (3.0) years. The mean (SD) spherical equivalent refraction (SER) was 0.56 (1.73) diopters (range: −4.75 to 4.75). The mean of macular average thickness was 277.2±12.5 μm, and the mean of the central subfield thickness was 246.7±16.8 μm. In multivariate analysis, all macular parameters except the central subfield thickness (CST) correlated positively with the SER. Boys had significantly higher CST than girls (p=0.008). None of the macular parameters were correlated with age.ConclusionNormative data of macular thickness for healthy Jordanian children were established for sex and age groups using SD-OCT.

Comparisons of Using Cycloplegic Biometry Versus Non-cycloplegic Biometry in the Calculation of the Cycloplegic Refractive Lens Powers.

This study investigated the difference between the calculation of cycloplegic crystalline lens power (LP) using non-cycloplegic and cycloplegic biometry data in children, and associated factors were explored. A total of 821 children were enrolled and only right eye was analyzed. The corneal radii (CR), corneal power (CP), anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) before and after cycloplegia were obtained using IOLMaster700. Anterior segment length (ASL) was defined as ACD plus LT. The cycloplegic LP was calculated with Bennett's formula. In addition, LP calculated with cycloplegic data was defined as cLP, otherwise it was defined as nLP. The ΔLP (defined as the value as cLP minus nLP) was compared among age, gender, and refractive states groups. Associated factors of ΔLP and |ΔLP| were explored by Pearson's correlation and multivariate linear regression. The mean age of the 821 subjects was 9.83 ± 2.97years with a mean spherical equivalent refraction (SER) of - 1.06 ± 2.12D. Overall, the ACD, LT, and ASL were significantly affected by cycloplegia agent (all p < 0.001; paired ttest). Conversely, no statistically significant differences were documented in AL, CP, or AL/CR ratio before and after inducing cycloplegia (p = 0.917, p = 0.515, and p = 0.549, respectively). Significant difference was found between nLP and cLP (21.24 ± 1.58D vs 21.43 ± 1.92D, p = 0.001). The mean ΔLP was 0.11 ± 0.87D (range from - 7.01D to 7.08D). Significant change in LP was found in low and medium groups, respectively (0.13 ± 0.81D, p = 0.001; 0.11 ± 0.48D, p = 0.043). In the multiple regression analysis, |ΔLP| was exclusively associated with ΔASL (β = 0.172, [95%CI 0.112-0.300], p < 0.001). Our results indicated that using cycloplegic biometry could lead to an overestimation in LP for low and moderate myopia eyes. This finding is likely to facilitate the refractive development research in children. ClinicalTrials.gov identifier, NCT05247099.

Evaluation of Visual and Patient-Reported Outcomes, Spectacle Dependence after Bilateral Implantation with a Non-Diffractive Extended Depth of Focus Intraocular Lens Compared to Other Intraocular Lenses.

Purpose: To evaluate postoperative outcomes, spectacle dependance and the occurrence of the photic phenomena in patients after cataract surgery following the implantation of a non-diffractive extended depth of focus (EDOF) intraocular lens was compared to monofocal and multifocal lenses. Methods: We enrolled patients with bilateral cataracts who wanted to reduce their dependence on glasses in the study. They were followed for 6 months. The study group in which the EDOF lens was implanted consisted of 70 eyes in 35 patients. The control groups consisted of: 52 eyes in 26 patients in whom a multifocal was implanted and 52 eyes in 26 patients with implanted monofocal lens. After a total of 2 weeks, 2 months and 6 months post-surgery the following were evaluated: uncorrected and corrected visual acuity at 4 m, 80 cm, 40 cm, manifest refraction expressed as mean refractive spherical equivalent (MRSE), contrast sensitivity, intraocular pressure. A questionnaire on independence from ocular correction, the occurrence of photic phenomena, and patient satisfaction was also completed. Results: Monocular and binocular visual acuity and MRSE 6 months after the procedure were compared between three groups. All of the main analyses, except for comparisons of uncorrected distance visual acuity (both monocular and binocular) level, were significant. Contrast sensitivity was lower among patients with multifocal lens than among patients with EDOF lens. Halo and glare after 6 months were seen more often among patients with multifocal lens than among patients with the other lens (65% of eyes with multifocal lens vs. 6% of eyes with EDOF lens and 0% of eyes with monofocal lens). Glasses were needed by 35% of patients with EDOF lens, and by 96% of patients with monofocal lens and in none of the patients with multifocal lens. Conclusions: Most patients qualify for the implantation of a non-diffractive EDOF lens. Post-operative visual acuity improves at any distance. The best monocular visual acuity for intermediate distances is provided by an EDOF lens, and for near distance by a multifocal lens. The EDOF lens definitely increases independence from spectacle correction compared to monofocal lenses; however, the greatest degree of independence from spectacles is provided by multifocal lenses. The incidence of photic phenomena is slightly higher than that of a monofocal lens, and much lower for a multifocal lens.

Simultaneous Presbyopia and Astigmatism Correction with a Novel Trifocal Toric Intraocular Lens-A One-Year Follow-Up.

The current investigation evaluates the efficiency of the trifocal toric Liberty 677MTY intraocular lens (IOL) in correcting preoperative corneal astigmatism in cataract patients demanding spectacle independence. The retrospective evaluation included 28 eyes of 15 patients with preoperative corneal astigmatism of at least 1.0 Dioptre (D). All patients were followed up for one year postoperatively. Residual refractive errors and visual acuities at multiple distances were measured. Binocular visual acuity and contrast sensitivity defocus curves were plotted. Visual functions and patient satisfaction were assessed. The efficiency of astigmatism correction was determined using the vector analysis method. The mean spherical equivalent refraction (SEQ) improved from 2.72 ± 1.62 D to 0.10 ± 0.48 D. The cylindric refraction decreased from 1.18 ± 0.45 D to 0.16 ± 0.31 D. Vector analysis proved efficient astigmatism correction with a centroid of 0.10 ± 0.34 D at 161°. Ninety-two percent of eyes resulted within 0.5 D from the target refraction. Visual acuities were 0.1 logMAR or better from +1.0 to −3.5 D defocus values. Visual tasks could be performed without major difficulties. Our patients were highly satisfied. Refractive and visual outcomes with the investigated presbyopia-correcting toric IOL are predictable and the lens provides excellent trifocal vision.

Part-time Versus Full-time Spectacles for Myopia Control (ParMA Study): A Randomized Clinical Trial.

IntroductionTo compare myopia progression in school-aged children of Caucasian origin wearing part-time vs. full-time full correction with single-vision spectacles.MethodsThis prospective, randomized controlled trial included 30 children with bilateral myopia, who received either full-time or part-time treatment with single-vision spectacle lenses. Myopia progression was assessed as the mean change in cycloplegic spherical equivalent refraction (SE), mean change in axial length (AL), and mean change in sub-foveal choroidal thickness (SChT), over a 12-month follow-up period.ResultsA total of 32 eyes were treated with part-time single-vision spectacles (intervention group) and 28 eyes with full-time single-vision spectacles (control group), respectively. The part-time treated group reported no spectacle use during near-work activities for a mean of 6.2 hours/day. At the 12-month assessment, there was no significant difference between part-time and full-time correction groups in mean SE change (MD: -0.05 D, 95% CI: -0.50 - 0.39 D; P 0.81), in mean AL change (MD: -0.07 mm; 95% CI: -0.20 - 0.06 mm; P 0.30), and in mean SChT change (MD: -11.45 μm; 95% CI -22.60 - 14.16 μm; P 0.67).ConclusionMyopia progression in Caucasian children treated with part-time, single-vision spectacle use was not different compared to full-time, single-vision spectacle use, over a 12-month follow-up period.

Pupil barycenter configuration in patients with myopia and hyperopia.

To compare the apparent chord mu between hyperopia and myopia cases and investigate the usefulness of iris barycenter configurations as an alternative for performing kappa angle distance calculations. This prospective study evaluated 394 eyes of 197 patients classified into two groups according to their spherical equivalent values: the myopic (mean spherical equivalent refraction ≤ - 0.50 D) and the hyperopia group (mean spherical equivalent refraction ≥ + 0.50 D). The two groups were further subdivided according to severity (myopic group: mild, ≤ - 0.50 and ≤ - 3.00 D; moderate, < - 3.00 and ≤ - 6.00 D; severe, < - 6.00 D; hyperopic group: mild, ≥ + 0.50 and ≤ + 2.00 D; moderate, > + 2.00 and ≤ + 4.00 D; severe, > + 4.00 D). The pupil and iris barycenter distance measurements and other parameters were obtained through optical low-coherence reflectometry. Of the 197 patients, 109 (55.3%) were female and 88 (44.7%) were male individuals; their ages ranged from 7 to 60years (mean, 35.16 ± 14.75years). The average pupil barycenter distances were 0.38 ± 0.15 and 0.21 ± 0.11mm in hyperopia and myopia patients, respectively (p < 0.01). Corneal and lens thickness measurements were higher in hyperopia patients (p < 0.01, p < 0.01, respectively), whereas anterior chamber depth and pupil diameter measurements were higher in myopia patients (p < 0.01, p < 0.01, respectively). No significant difference in astigmatism or white-to-white measurements was observed between hyperopia and myopia patients (p > 0.05). The measurements for the apparent chord mu of the pupil and iris barycenter origins were higher in hyperopic than in myopic cases.

Applying Information Gain to Explore Factors Affecting Small-Incision Lenticule Extraction: A Multicenter Retrospective Study.

PurposeThis retrospective study aimed to identify the key factors influencing postoperative refraction after small-incision lenticule extraction (SMILE) using information gain.MethodsThis study comprised 2,350 eyes of 1,200 patients who underwent SMILE using a Visumax 500-kHz femtosecond laser (Carl Zeiss Meditec AG) in three ophthalmic centers: Tianjin Eye Hospital (center A), Jinan Mingshui Eye Hospital (center B), and Qingdao Eye Hospital (center C). Anterior segment features, including corneal curvature and central corneal thickness (CCT), were obtained from Pentacam HR (Oculus, Wetzlar, Germany). Information gain was calculated to analyze the importance of features affecting postoperative refraction.ResultsPreoperative and postoperative mean spherical equivalent (SE) refraction were −5.00 (−6.13, −3.88) D and 0.00 (−0.25, 0.13) D, respectively. None of the patients lost more than two lines of corrected distance visual acuity. The safety index was 1.32 ± 0.24, 1.03 ± 0.08, and 1.13 ± 0.16 in centers A, B, and C, respectively. The efficacy index was 1.31 ± 0.25, 1.02 ± 0.08, and 1.13 ± 0.17 in centers A, B, and C, respectively. At least 95% of the eyes were within ±1.00 D of the attempted correction. Postoperative refraction was related to preoperative spherical diopter refraction (r = 0.369, p < 0.001), preoperative SE (r = 0.364, p < 0.001), maximum lenticule thickness (r = −0.311, p < 0.001), preoperative uncorrected distance visual acuity (r = 0.164, p < 0.001), residual stromal thickness (r = 0.139, p < 0.001), preoperative mean anterior corneal curvature (r = −0.127, p < 0.001), preoperative flattest anterior corneal curvature (r = −0.122, p < 0.001), nomogram (r = −0.100, p < 0.001) and preoperative CCT (r = −0.058, p = 0.005).ConclusionsSMILE was considered a safe and effective procedure for correcting myopia. Based on information gain, postoperative refraction was influenced by preoperative mean anterior corneal curvature, CCT, refraction, and residual stromal thickness.

Effect of Time Outdoors and Near-viewing Time on Myopia Progression in 9- to 11-year-old Children in Chongqing.

We used an Akeso device to record the visual behavior of children with myopia in two learning modes. We found that online class mode may increase near-viewing time and reduce outdoor time compared with the traditional school mode and may be responsible for accelerating myopia progression. We aimed to explore the effects of visual behavior in different learning modes on myopia progression among children 9 to 11 years old. Forty-nine children were included and requested to use a wearable device to objectively record visual behavior in real time from November 2019 to November 2020; participants took online classes from mid-February to early May 2020 during this period. Data (including glasses-wearing time, outdoor time, and near-viewing time) were collected during two 14-day periods, which included the online class learning mode (March 2 to 15, 2020) and the traditional school mode (May 20 to June 2, 2020). Spherical equivalent refraction and axial length were obtained at baseline, at 6-month intervals, and 1 year later. Outdoor time during online class mode (median, 9.5 minutes; interquartile range, 0.75 to 48 minutes) was significantly lower than during the school mode (median, 29 minutes; interquartile range, 11.50 to 50 minutes; P < .001). The mean ± standard deviation of near-viewing time was significantly different between online class mode (396.58 ± 114.41 minutes) and school mode (376.52 ± 93.99 minutes; P = .007, F = 19.56). In comparison with the baseline examination (-2.33 ± 0.81 D), mean spherical equivalent refraction in oculus dexter corresponding to the 6-month examination was decreased (-2.94 ± 0.83 D, P = .001), indicating a significant increase in myopia during online class mode. This study provides evidence of the association of learning mode and myopia progression. Accelerated progression of myopia in online class mode may be related to increased near-viewing time and decreased time spent in outdoor activities.

Comparison of Efficacy and Safety Between Standard, Accelerated Epithelium-Off and Transepithelial Corneal Collagen Crosslinking in Pediatric Keratoconus: A Meta-Analysis

PurposeThe purpose of the study is to compare the efficacy of standard epithelium-off CXL (SCXL), accelerated epithelium-off CXL (ACXL), and transepithelial crosslinking CXL (TECXL) for pediatric keratoconus.MethodsA literature search on the efficacy of SCXL, ACXL, and TECXL [including accelerated TECXL (A-TECXL)] for keratoconus patients younger than 18 years was conducted using PubMed, Cochrane Library, ClinicalTrials.gov, and EMBASE up to 2021. Primary outcomes were changes in uncorrected visual acuity (UCVA) and maximum keratometry (Kmax) after CXL. Secondary outcomes were changes in best-corrected visual acuity (BCVA), mean refractive spherical equivalent (MRSE), and central corneal thickness (CCT). Estimations were analyzed by weighted mean difference (WMD) and 95% confidence interval (CI).ResultsA number of eleven identified studies enrolled 888 eyes (SCXL: 407 eyes; ACXL: 297 eyes; TECXL: 28 eyes; A-TECXL: 156 eyes). For pediatric keratoconus, except for a significant greater improvement in BCVA at 24-month follow-up in SCXL (WMD = –0.08, 95%CI: –0.14 to –0.01, p = 0.03, I2 = 71%), no significant difference was observed in other outcomes between the SCXL and ACXL groups. SCXL seems to provide greater changes in UCVA (WMD = –0.24, 95% CI: –0.34 to –0.13, p < 0.00001, I2 = 89%), BCVA (WMD = –0.09, 95% CI: –0.15 to –0.04, p = 0.0008, I2 = 94%), and Kmax (WMD = –1.93, 95% CI: –3.02 to –0.85, p = 0.0005, I2 = 0%) than A-TECXL, with higher incidence of adverse events.ConclusionFor pediatric keratoconus, both SCXL and ACXL appear to be comparable in the efficacy of visual effects and keratometric outcomes; SCXL seems to provide greater changes in visual and pachymetric outcomes than A-TECXL.

In vivo analysis of ciliary muscle in myopic Chinese young adults using ArcScan Insight® 100.

To analyse the morphological characteristics of the ciliary muscle (CM) and to explore its relationship with different ocular biometric parameters in myopic young Chinese adults. This observational, cross-sectional study included 50 right eyes from 50myopic adults. The CM area (CMA), CM thickness (CMT) and CM length (CML) were measured using the ArcScan Insight® 100. CMT was determined at three points: 1.0mm (CMT-1), 2.0mm (CMT-2) and 3.0mm (CMT-3) posterior to the scleral spur. CML was measured on the scleral (CMLs) and vitreous (CMLv) aspects. The spherical equivalent refraction (SER), axial length (AL) and subfoveal choroidal thickness (SFCT) were examined to determine their associations with CM parameters (CMA, CML and CMT). The mean SER and AL were -4.39±2.29 D and 25.61±1.15mm, respectively. Compared with the nasal CMA, CML and CMT (CMT-1, CMT-2 and CMT-3) findings, the temporal CM parameters (CMA, CMLs, CMLv, CMT-1, CMT-2 and CMT-3) were found to be significantly thicker (all p<0.001, except CMLv and CMT-1; p<0.01). The nasal CMA was associated with the average corneal curvature (r=0.30, p=0.03) and SER (r=-0.30, p=0.04). Nasal and temporal CMT-2 were negatively correlated with SER (r=-0.33 and -0.32, respectively, both p<0.05). There was no correlation between CM parameters (except nasal CMLs, r=0.31, p=0.03) and SFCT, or between CM parameters and either the AL or anterior chamber depth (all p>0.05). These results suggest that there is temporal versus nasal asymmetry of the CM. CMA, CMT or CML did not vary with axial growth of the eye. The CM is not simply stretched as the eye elongates in myopic young adults.

Refractive changes during off-the-axis retinoscopy in myopia.

Purpose:To analyze the refractive shift during off-the-axis retinoscopy under cycloplegic drugs in myopic patients during ocular examination.Methods:Prospective cross-sectional study was carried out among 10 myopic patients having refractive errors of −3.00 D or less. All the subjects underwent cycloplegic refraction by a single examiner at 0°, 10°, and 20°. Descriptive data were analyzed as mean and standard deviation. Paired t-test was used to compare the mean differences between on-axis (0°) and off-axis (10° and 20°) retinoscopy.Result:The mean spherical equivalent refraction of 10 myopic patients showed an increase in myopic shift with approximately 7% and 18% for 10° and 20° of eccentricity, respectively. Similarly, the mean spherical equivalent measure on axis (0°) and off axis (10° and 20°) were -2.5495, −2.737, and −3.0265, respectively. The mean spherical equivalent differences between on-axis (0°) and off-axis (10° and 20°) showed statistically significant differences with P < 0.05.Conclusion:This study concluded that a greater degree of eccentricity will induce a greater amount of errors in retinoscopy.

Commentary: Renewed interest in off-axis retinoscopy and peripheral refraction for it's role in control of myopia progression.

We all know that vision is a combination of optical input and neural processing. Traditionally, retinoscopy has remained the benchmark for the assessment of refractive errors for the optical input that is perceived by the eye and then processed by the brain. Conventionally, it has always been known that “on the visual axis” (on-axis) retinoscopy gives a more accurate estimate of refractive error compared to retinoscopy that is done off the visual axis (off-axis). However, in practical terms, retinoscopy is frequently performed slightly off the visual axis and there are situations in which on the visual axis retinoscopy is difficult or even impossible. These include retinoscopy in uncooperative children or when the subject has been anesthetized. Chaurasiya et al.[1] in their current study on “refractive changes during off-the-axis retinoscopy in myopia” and many other researchers, over the years have tried to quantify the error in the quantum of refractive error when this is measured with “off-axis” retinoscopy in routine clinical practice. Ferree et al.[2] in 1931 measured peripheral refraction with the Zeiss parallax refractometer (Carl Zeiss, Jena, Germany). Rempt et al.[3] was the first to perform eccentric retinoscopy and introduced the skiagram to categorize different peripheral refractive error patterns. Jackson et al.[4] examined off the visual axis retinoscopy in eight adults (spherical equivalent <±2.5 D) who had undergone cycloplegia. The degrees of the eccentricity of up to 20° along the temporal horizontal field were examined and they found a myopic shift of 5% in spherical equivalent and an increase in cylindrical power of 3% for every degree of eccentricity. In the present study, the authors have noted an increase in myopic shift with approximately 7 and 18% for 10 and 20° of eccentricity, respectively, in the mean spherical equivalent refraction of 10° myopic patients. What is traditionally believed and agreed upon is that the error in refraction, which is noted in off-axis retinoscopy, is generally small and clinically insignificant when the deviation of axis and the quantum of refractive error is small, and more often than not, this error is eliminated in the process of subjective refraction which follows retinoscopy. However, this error in retinoscopy can become significant if the deviation of the axis of retinoscopy from the visual axis is large or if the quantum of refraction being measured is large, for example, as in high myopia.[5] Of late, there has been renewed interest in the measurement of peripheral refraction as it is increasingly believed that peripheral refractive defocus plays a role in myopia progression by inducing axial growth of the eye. Animal studies have shown that depending on the location of the image relative to the retina, axial elongation can be stopped or triggered. Experiments in chickens and monkeys whose vision were defocused either with negative spectacle lenses (hyperopic defocus) or positive lenses (myopic defocus), showed that their visual system was altering their refractive state by accelerating or slowing axial elongation in order to compensate for the imposed defocus.[6] This applies both in the fovea and in the periphery of the retina. Originally, it was believed that only foveal optical errors could regulate eye growth, but it is now believed that peripheral image quality can also modify ocular growth even in the presence of a sharp foveal image. This is the reason that many researchers have advocated the use of bifocal or progressive addition lenses (PAL) for children as a strategy to retard the progression of myopia, but as of now, there is no consensus regarding their clinical efficacy.[7] Studies with PAL have typically shown a small but clinically insignificant effect on slowing myopia progression as noted in Cochrane review 2020.[8] A meta-analysis noted small reductions in myopia progression (0.25 D) and axial elongation (−0.12 mm).[9] So, there is indeed a value in studying the variation of refractive error assessment between the on-axis and off-axis retinoscopy but more work needs to be done to have more clarity regarding the clinical application of this work, especially in control of myopia progression.

Refractive Outcomes After LASIK for the Treatment of Mixed Astigmatism with the Allegretto WaveLight EX500.

IntroductionTreatment of mixed astigmatism with laser in situ keratomileusis (LASIK) is complex as the correction requires flattening the cornea in one meridian while steepening the cornea in the other meridian. The bitoric technique has become the most popular approach and has been tested across a variety of platforms. This study is the first to evaluate the results of mixed astigmatism treatment using the Allegretto WaveLight® EX500.MethodsThis study was a single-center, retrospective, noncomparative analysis of 400 eyes that underwent LASIK to correct for mixed astigmatism utilizing the EX500 excimer laser. Data on uncorrected distance visual acuity, corrected distance visual acuity, and spherical equivalent was analyzed at consecutive intervals (1, 3, 6, 9, and 12 months). Refractive measurements were used to perform a vector analysis.ResultsThree and 12 months postoperatively, 71% and 74% of eyes had an uncorrected distance visual acuity (UDVA) of 20/20 or better and 99% and 100% of eyes had a UDVA of 20/40 or better, respectively. The postoperative UDVA was within one line of the corrected distance visual acuity (CDVA) in 88% and 93% of eyes at 3 and 12 months, respectively. At 3 months, 78% of eyes achieved refractive astigmatism no greater than 0.50 diopters and at 12 months, 80% achieved this. The mean spherical equivalent refraction was − 0.36 ± 0.57 D at 12 months after surgery. At the 12-month follow-up, the mean refractive cylinder was reduced by 87%, from − 2.79 to − 0.37 diopters. On vector analysis, 99% of eyes had an angle of error within ± 15° from the intended target at 3 and 12 months.ConclusionTreatment of mixed astigmatism using the Allegretto WaveLight® EX500 laser exceeded the industry standards of safety, efficacy, stability, and accuracy.

Annual Incidences and Progressions of Myopia and High Myopia in Chinese Schoolchildren Based on a 5-Year Cohort Study.

PurposeTo determine the annual incidences and rates of progression of myopia and high myopia in Chinese schoolchildren from grade 1 to grade 6 and explore the possible cause-specific risk factors for myopia.MethodsFrom 11 randomly selected primary schools in Anyang city, central China, 2835 grade 1 students were examined with annual follow ups for 5 years. Students were invited to undergo a comprehensive examination, including cycloplegic autorefraction, ocular biometry, and standardized questionnaires.ResultsThe mean spherical equivalent refraction decreased substantially from +0.94 ± 1.03 diopter (D) in grade 1 to −1.37 ± 2.08 D in grade 6, with rapid annual myopic shifts, especially for students in grades 3 through 6 (−0.51 to −0.59 D). The prevalence of myopia increased substantially, with the yearly incidence of myopia increasing from 7.8% in grade 1 and 2 to 25.3% in grades 5 and 6, and the incidence of high myopia increased from 0.1% to 1.0%. The 5-year incidence of myopia was lowest among children who has a baseline spherical equivalent refraction of greater than +2.00 D (4.4%), and increased to nearly 92.0% among children whose baseline spherical equivalent refraction was 0.00 to −0.50 D. The incidence of myopia was higher in children who had less hyperopic baseline refraction, two myopic parents, longer axial length, deeper anterior chamber, higher axial length–corneal radius of curvature ratio, and thinner lenses.ConclusionsBoth the annual incidence and progression rates of myopia and high myopia were high in Chinese schoolchildren, especially after grade 3. Hyperopic refraction of children should be monitored before primary school as hyperopia reserve to prevent the onset of myopia and high myopia.

Twelve-month outcomes of a new refractive lenticular extraction procedure

BackgroundTo evaluate the 12-month refractive and visual outcomes of Small Incision Guided Human-cornea Treatment (SmartSight®, SCHWIND eye-tech-solutions, Kleinostheim, Germany) in the treatment of myopia corrections with low to moderate astigmatism with the use of a new femtosecond laser system. Methods221 eyes of 114 patients consecutively treated with SmartSight lenticule extraction were assessed. The mean age of the patients was 28±6 years at the time of treatment with a mean spherical equivalent refraction of -6.26±2.17D and mean astigmatism of 0.92±0.68D. Monocular corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) were assessed pre- and post-operatively. Refractive changes have been determined in terms of changes in refraction, as well as changes in keratometric readings. The changes in central epithelial thickness have been determined. ResultsAt twelve months post-operatively, mean UDVA was 20/21±2. Spherical equivalent showed a residual refraction of +0.48±0.31D with refractive astigmatism of 0.13±0.18D postoperatively. There was a slight decrease of -0.1 Snellen lines at 12-months follow-up. The same correction was determined using changes in refraction, as well as changes in keratometric readings. The central epithelial thickness increased by +3±2µm. Spherical equivalent correction within ±0.50D was achieved in 199 eyes (90%), and cylindrical correction in 221 (100%). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 213 eyes (96%), and postoperative uncorrected (UDVA) was 20/20 or better in 205 eyes (93%). No eye had lost two or more Snellen lines of CDVA. ConclusionsMyopic astigmatism correction with SmartSight provided good results for efficacy, safety, predictability, and visual outcomes at the twelve months of follow up. The central epithelial thickness barely increased by 3±2µm.

One year outcomes after small incision lenticule extraction ReLEX in the correction of myopia and myopic astigmatism

PurposeTo report the visual and refractive outcomes of small incision lenticule extraction ReLEX (SMILE) technique using VisuMax femtosecond laser in myopia and myopic astigmatism patients.Material and methodsA non-randomized clinical study has been conducted on patients with myopia and myopic astigmatism who underwent ReLEX SMILE technique, using the Zeiss VisuMax Laser system (Carl Zeiss Meditec AG, Jena, Germany) at Oculens Clinic, Cluj-Napoca, Romania. Patients older than 18 years, with ocular astigmatism up to -5 diopters (D), spherical equivalent up to -10.00 D, corrected distance visual acuity (CDVA) of 0.3 or better before the surgery, stable refraction for one year, and with a minimum calculated post operator residual stromal bed of 250μ were included in the study.ResultsThe study involved a total of 25 myopic eyes (median of sphere diopters equal with -4D) and 67 myopic astigmatic eyes (median of cylinder diopters equal with -1.5 D). The mean refractive spherical equivalent (MRSE) on patients with myopic eyes reduced from -4.25D (median) to -0.5D at one month follow-up, -0.25 D at 6 and 12 months. The mean refractive spherical equivalent (MRSE) on patients with astigmatic myopic eyes reduced from-6.25 D to -0.67 D at one month, -0.62 D at six and twelve months. The value of sphere decreased postoperatively on myopic eyes with a median of -0.25D at one, six and twelve months. The value of cylinder decreased postoperatively on myopic astigmatic eyes with a median of -0.50 D at one month, -0.25 D at six months and -0.50 D at 12 months. At 6 and 12 months, 20 (80.0%) of myopic eyes were maintained within ±0.5 D and 22 (88.0%) with ±1D. On both groups (myopic eyes and myopic astigmatic eyes), statistically significant differences were observed when the keratometric baseline values were compared to each follow-up (P-values < 0.0001), without any significant differences between follow-ups (P-values>0.15). At 1-month follow-up, uncorrected distance visual acuity (UDVA) was better than or equal to 0.5 in 88.0% of myopic eyes and 82.1% of myopic astigmatic eyes. UDVA remained stable in all cases of myopic eyes at six months and the percentage increased at 92.0% in myopic eyes. UDVA slightly increased at 6-months (85.1%) and remained at the same value at 12-months in myopic astigmatism eyes.ConclusionsSMILE proved an effective and safe refractive corneal procedure and provided a predictable and stable correction of myopia and myopic astigmatism. SMILE technique demonstrated very good outcomes in terms of keratometric, cylinder, spherical measurements.

Relationship between axial length and spherical equivalent refraction in Chinese children

PurposeTo evaluate the relationship between axial length (AL) and spherical equivalent refraction (SER) in Chinese children. MethodsThis hospital-based cross-sectional study included 1208 eyes (from 617 Chinese boys and 591 Chinese girls), ranging between 2 and 12 years. All subjects were divided into subgroups according to the spherical equivalent refraction (SER) (hyperopia, emmetropia, and myopia) and age (2–6 years, 7–9 years, and 10–12 years). Comparisons were made between age, sex, and SER groups. Multiple linear regression analysis was used to evaluate the correlation of AL and SER for all groups. ResultsThe mean AL and SER were significantly different among the three age groups: 2–6 years group (AL: 22.24 ​± ​1.59 ​mm; SER: 0.73 ​± ​2.67 D); 7–9 years group (AL: 23.49 ​± ​1.10 ​mm; SE: -0.68 ​± ​1.97 D) and 10–12 years group (AL: 24.33 ​± ​1.02 ​mm; SER: -1.72 ​± ​1.86 D). Boys showed longer AL compared with the girls (23.66 ​± ​1.51 ​mm vs 23.05 ​± ​1.32 ​mm). However, as for SER, the girls (−0.70 ​± ​2.17 D) showed smaller SER (more myopia) compared with the boys (−0.4 ​± ​2.48 D). After adjusting for age and sex, the SER tended to decrease (became more myopic) 1.23 D (95% CI: 1.15–1.30D) with a 1 ​mm increase of AL. Among the different SER groups, the SER tended to become more myopic per mm of AL by 1.09 D (95% CI: 0.97–1.21D) for the myopia group, 1.38 D (95% CI: 1.23–1.54 D) for the hyperopia group, and 0.05 D (95% CI: 0.02–0.08 D) for the emmetropic group. In addition, an increase of 1 ​mm elongation of AL showed a decrease of SER by 1.05 D (95% CI: 0.90–1.20 D) among 2 – 6-year-olds, by 1.40 D (95% CI: 1.30–1.51 D) among 7 – 9-year-olds, and by 1.37 D (95% CI: 1.21–1.52 D) among 10–12-year-olds. As for sexual differences, the girls 1.68 D, (95% CI: 1.57–1.79 D) showed a more significant myopic shift of SER with a 1 ​mm increase of AL compared with the boys (0.94 D, 95% CI: 0.84–1.04 D). ConclusionsOur results indicated a strong linear relationship between SER and AL and an early-rising trend of myopia in Chinese children.

One-Year Outcomes of Intracorneal Ring-Segment Insertion Assisted by Femtosecond Laser Simultaneously Performed with Corneal Collagen Cross-Linking for Treatment of Keratoconus.

PurposeTo assess the results of simultaneously performed femtosecond laser–assisted Keraring intrastromal corneal ring–segment insertion and corneal collagen cross-linking for the treatment of keratoconus.Patients and MethodsIn this retrospective, noncomparative, interventional study, 30 eyes of 24 progressive-keratoconus patients of both sexes aged 18–36 years old with poor best-corrected visual acuity (BCVA) and intolerance to contact lenses were included. All patients had been subjected to complete preoperative and postoperative ophthalmological examinations — unaided VA, BCVA, refraction, Pentacam, and contrast sensitivity examinations at 3-month, 6-month, and 1-year follow-ups.ResultsMean unaided VA had changed significantly from 0.649±0.239 logMAR preoperatively to 0.514±0.222 (P=0.014), 0.419±0.162 (P<0.001), and 0.379±0.142 (P<0.001) logMAR at the three follow-up visits, respectively. Mean BCVA had changed significantly from 0.326±0.144 logMAR preoperatively to 0.231±0.140 (P=0.006) at 1-year follow-up. Mean spherical equivalent refraction had decreased significantly at 6-month (P=0.0298) and 1-year follow-up (P=0.0081). Mean steep keratometry (K2) had also significantly reduced from 51.89±3.81 D to 49.87±4.57 D (P=0.034) at 6 months and 49.40±4.39 D (P=0.011) at 1 year. Mean refractive and keratometric astigmatism had significantly decreased at all follow-up visits.ConclusionAt 1-year follow-up, keraring intrastromal corneal ring–segment insertion assisted by femtosecond laser performed simultaneously with corneal collagen cross-linking resulted in an improvement in visual, refractive, and topographic outcomes, which may suggest it is an effective treatment of keratoconus.