Change In Refractive Error Research Articles

Impact of Genetic and Environmental Factors on Peripheral Refraction.

Investigate genetic and environmental influences on refractive errors in monozygotic (MZ) and dizygotic (DZ) twin pairs. We assessed foveal and peripheral refractions in 54 MZ and 46 DZ twins, capturing three scans across the retina. The study focused on spherical equivalent (M) at the fovea (MLOS) and changes in midperipheral (δMmid-periphery), and peripheral (δMperiphery) defocus, along with nasal-temporal asymmetry (root mean squared error [RMSEASY]) and image shell contour (RMSEAVG). Genetic and environmental contributions were analyzed using structural equation models. No significant differences were observed between MZ and DZ twins for the examined variables. Intraclass correlations (ICC) indicated an important difference in genetic influence between MLOS, with the MZ twin pairs showing a higher correlation (0.83) than DZ (0.69) pairs, and δMperiphery, because the ICC for the MZ doubled (0.87) that of the DZ (0.42) pairs. Heritability estimates from the ACE model confirmed the large difference on genetic factors' influence on the variance for MLOS (0.13) and δMperiphery (0.77) change in refractive error. RMSEASY and RMSEAVG metrics showed significant genetic impact, particularly pronounced in the peripheral measurements, revealing high genetic control. The study delineates a marked environmental impact on central refractive errors, whereas genetic factors had a more significant influence on peripheral refractive variance and retinal image traits. Findings of the ACE model highlight the intricate genetic and environmental interplay in refractive error development, with a notable genetic dominance in peripheral vision characteristics. This suggests potential genetic targets for interventions in myopia management and emphasizes the need for personalized approaches based on genetic predispositions. Understanding the impact of genetics and environment on peripheral refraction is essential for deepening our fundamental knowledge of myopia and guiding the development of advanced myopia control strategies.

Longitudinal refractive errors over 36 months in Hispanic and Black children.

This study brings awareness of racial/ethnic difference of refractive error characteristics in clinics. This study aimed to assess longitudinal change in refractive errors over a 36-month period in Hispanic and Black children. Children (2.4 to 15 years old) were studied. Cycloplegic refraction was measured annually. Spherical equivalent was calculated. Astigmatism was evaluated by magnitude of cylinder and power vector (J0 and J45). Absolute value of interocular spherical equivalent difference was used to calculate anisometropia. Mixed-linear model was used to analyze longitudinal annual change in spherical equivalent, cylinder, J0, and J45 over 36 months. A total of 485 participants (310 Black, 175 Hispanic) met the criteria. At the baseline examination, prevalence of myopia, emmetropia, and hyperopia was 39% (n = 187), 31% (n = 150), and 30% (n = 148), respectively. Spherical equivalent of Black children was not significantly different from that in Hispanic children (0.10 ± 2.92 vs. -0.37 ± 2.05 D, p=0.06); however, the Hispanic children had a significantly higher cylinder compared with Black children (Hispanic: 1.46 ± 1.57 D vs. Black: 0.92 ± 1.07 D; p<0.001). Both J0 (p<0.001) and J45 (p=0.01) were significantly different between two groups; the Hispanic children had more with-the-rule astigmatism and oblique astigmatism than the Black children. Prevalence of anisometropia (≥1 D) was higher in Black children (14%) compared with Hispanic children (5%, p=0.006). Over 36 months, spherical equivalent significantly decreased an average of 0.69 D (0.23 D/y, p<0.001) for both groups; neither astigmatism nor anisometropia changed significantly (p>0.05). Astigmatism in the Hispanic children was significantly higher than in Black children. However, the Black children had a higher prevalence and degree of anisometropia than the Hispanic children.

Myopic Shift over 5 Years after Pediatric Lensectomy with Primary Intraocular Lens Implantation

To report the change in refractive error over 5 years following primary intraocular lens (IOL) placement by age at surgery, and to identify factors associated with the change in refractive error after 5 years. Prospective observational study at 61 pediatric eye care practices. 186 eyes of 152 children undergoing primary IOL implantation before 13 years of age for non-traumatic cataract. Cataract surgery with primary IOL placement MAIN OUTCOME MEASURES: Five-year change in refractive error (spherical equivalent) by age at surgery (<1 year; 1 to <2.5 years; 2.5 to <4 years; 4 to <7 years; 7 to <13 years). Five-year myopic shift in children 4 to <13 years with immediate postoperative myopia vs emmetropia or hyperopia. Mean spherical equivalent myopic shift (95% confidence interval [CI]) was -5.99 D (-7.64 to -4.34) when surgery was performed at 0 to <1 year of age (n=13), -3.53 D (-4.57 to -2.48) at 1 to <2.5 years (n=28), -1.91 D (-2.55 to -1.26) at 2.5 to <4 years (n=36), -2.04 D (-2.60 to -1.49) at 4 to <7 years (n=60), and -0.83 D (-1.27 to -0.40) at 7 to <13 years (n=49) (P<.01 for each comparison with the oldest group). Variability of myopic shift also decreased with increasing age (P<.01). In eyes of children 4 to <13 years (small sample size precluded analysis of children <4 years), there was significantly less mean change [95% CI] in refractive error over 5 years in eyes with myopia immediately after surgery (-0.69, 95% CI -1.48 to +0.10) than eyes with emmetropia/hyperopia immediately after surgery (-1.70, 95% CI -2.10 to -1.31) (difference = -1.01 D, 95% CI -1.89 to -0.14 D, P=.03). In this large, prospective cohort study of children younger than 13 years of age undergoing cataract surgery with primary IOL placement, there was greater and more variable myopic shift in children undergoing surgery at a younger age. Our finding of less myopic shift over 5 years in eyes with unintended immediate postoperative myopia deserves further study to more accurately guide IOL power selection.

The efficacy of orthokeratology lenses with smaller back optic zone diameter in myopia control. A meta-analysis.

This study was conducted to determine whether orthokeratology (OK) lenses with a smaller back optic zone diameter (BOZD) could exhibit stronger myopia control effects. A meta-analysis was registered in PROSPERO (CRD42023408184). A comprehensive systematic database search was conducted, encompassing PubMed, Cochrane Library, EMBASE, MEDLINE, Web of Science, Ovid, CNKI and CBM, to identify relevant studies up to 25 March 2023. The primary inclusion criteria for this meta-analysis were studies that investigated the myopia control effect of OK lenses with a small optical treatment area (≤5 mm). To assess the quality of the retrieved articles, two researchers evaluated them using the Cochrane bias risk assessment criteria. The primary outcome measures were the changes in axial length (AL) and refractive error, using the weighted mean differences (WMD) and 95% confidence intervals (CI) to assess differences between small and traditional back optical treatment zone groups in terms of these outcomes. The analysis encompassed five eligible studies, with a 1 year duration. The average difference in AL between the groups was 0.12 mm (WMD = -0.12, 95% CI [-0.16, -0.09], p < 0.00001). Likewise, the average difference in refractive error between the two groups was 0.44 D (WMD = 0.44, 95% CI [0.30, 0.57], p < 0.00001). None of the studies reported severe adverse events. Current evidence suggests that OK lenses with smaller back optical treatment zone are more effective in preventing myopia progression than traditional lenses. However, a longer-term evaluation is warranted.

Clinical Efficacy of MiSight 1 day Soft Contact Lenses in Korean Myopic Children.

This study aimed to investigate the clinical efficacy of MiSight 1 day soft contact lenses (MiSight CL) in Korean children with mild-to-moderate myopia. In addition, the study compared the effects of MiSight CL in children who had or had not previously used orthokeratology contact lenses (Ortho-K). A total of 66 children aged 5 to 16 years, who were prescribed MiSight CL, were included in the study. Based on a myopia degree of -4 diopters (D), children were divided into mild and severe myopia groups to compare the effectiveness of myopia suppression. In addition, 55 eyes previously using Ortho-K were compared with 76 eyes using MiSight CL for the first time. The average follow-up period was 6.58±3.74 months. The average refractive value before using MiSight CL was 3.64±1.56 D, and there was no significant change in the final visit. Comparing myopia suppression between different degrees of myopia and previous use of Ortho-K lenses, there was no significant change in refractive error before and after using MiSight CL (unpaired t test, P >0.05). The main reason for Ortho-K failure was low visual acuity after correction. Regardless of Ortho-K history, children showed good visual acuity after wearing MiSight CL, and no other side effects were observed. MiSight CL effectively inhibited the progression of myopia in Korean children with mild-to-moderate myopia. MiSight CL offer the advantage of easy application, making them a viable alternative when Ortho-K are not suitable.

Temporal vascular arcade angle in fundus image was associated with the rate of spherical equivalent refractive error and axial length changes in myopia children with young school age

PurposeTo evaluate temporal vascular arcade angle and its influencing factors in myopic children. MethodsIt was a retrospective study, we reviewed the records of 119 patients aged 6–10 years with myopia (spherical equivalent refractive error (SER) ≤ -0.05D) in the third year of follow-up in Beijing Hyperopia Reserve Research. We measured temporal vascular arcade angles on the fundus photographs and measured 3-year rate of spherical equivalent(D/year) and axial length (AXL) changes(mm/year). ResultsMean age at initial visit was 7.71±1.20 years and mean SER was -1.32±1.09D. Children were divided into two groups according to the refractive status of children at baseline: Myopia onset group (SER>-0.50D at baseline) (n = 107) and Myopia progression group (SER≤-0.50D at baseline) (n = 12). The mean SER in Myopia progression group was much smaller than Myopia onset group (P < 0.001) and mean AXL in Myopia progression group was much longer than Myopia onset group (P = 0.042). AXL (r=-0.320, P < 0.001), SER change rate (r=-0.209, P = 0.022) and AXL change rate (r=-0.232, P = 0.011) were associated with temporal vascular arcade angle in all participants. In Myopia onset group, AXL (r=-0.317, P < 0.001) and AXL change rate (r=-0.190, P = 0.05) were associated with temporal vascular arcade angle. There were no parameters were associated with temporal vascular arcade angle (all P > 0.05) in Myopia progression group. Only AXL (r=-0.306, P = 0.018) was associated with temporal vascular arcade angle in girls while AXL (r=-0.370, P = 0.004), SER change rate (r=-0.317, P = 0.013) and AXL change rate (r=-0.365, P = 0.004) were all associated with the Angle in boys. ConclusionTemporal vascular arcade angle was associated with the rate of SER and AXL changes in myopia onset children, and showed gender differences. These may suggest that lamina cribrosa location has different influencing factors in different genders and different stages of myopia development. Due to the small number of people in Myopia progression group, large sample size studies are still needed in the future.

The Impact of Optimized Blinking on Vision and Related Parameters in Individuals With Computer Vision Syndrome: A Single-Blind Randomized Controlled Trial.

Computer vision syndrome (CVS) has become a significant issue for individuals working on computers and digital devices for extended periods. The ocular and periocular symptoms and signs associated with CVS are a major concern, affecting individuals physically and financially. Additionally, CVS has been linked to the rapid progression of myopia, exacerbating the situation. Blinking has been one of the major treatment methods for the treatment of CVS. This study presents a unique and novel randomized controlled therapeutic trial that evaluates the impact of extended blinking therapyon eyehealth and vision, along with other related parameters. Materialsandmethods: The present studyis a randomized controlled trial conducted from September 2022 to April 2024. Participants aged 18-40 with CVSand a computer vision syndrome questionnaire (CVS-Q)score of ≥6, with mild to moderate refractive error (between -6D and +4D), were included. The sample size was determined based on a pilot study, resulting in a minimum required sample size of 36 patients (18 cases and 18 controls). Participants were randomly assigned to either the case (interventional) or control (conventional) group and were followed up for six months. Cases received conventional CVS treatment plus optimized blinking exercises, while controls received conventional therapy only. Comprehensive ocular assessments were conducted bi-monthly over six months, evaluating changes in uncorrected visual acuity (UCVA), refractive error, near point of accommodation (NPA), near point of convergence (NPC), Schirmer's test, and tear film breakup time (TBUT). The study included 20 patients in the case group and 18 in the control group, primarily aged 20-29 (60.5%). Most patients used laptops for their activities (55.26%). The CVS-Q score significantly decreased in both groups following treatment, with both cases and controls showing significant improvement (p<0.001 for both groups). UCVA in the right eye (RE) and left eye (LE) of the cases improved significantly post-treatment in the interventional group (RE: p=0.002; LE: p<0.001). A significant change in refractive error, which is measured as spherical equivalent (SE), was seen among cases following treatment (RE: p<0.001; LE: p=0.021). Controls showed no significant changes in visual acuity or refractive error. The NPAin the cases improved significantly in the RE (p=0.027) but not in the left. The NPC in the intervention group showed no significant change, while controls showed considerable improvement (p=0.042). Schirmer's test results showed no significant change in either group. However, TBUTin the cases improved significantly (RE: p<0.001; LE: p<0.001). In the controls, TBUT decreased significantly, indicating a deterioration in tear film stability. Asthenopia grades improved considerably in cases, while controls showed only some improvement. Severe symptoms still remained in the control group, emphasizing the potential benefits of the blinking exercise in reducing asthenopia symptoms. Optimized blinking therapy significantly improves vision and refractive error, tear film stability, and discomfort, making it beneficial for chronic computer users to maintain ocular health and enhance productivity and quality of life.

High myopia: Reviews of myopia control strategies and myopia complications.

Myopia and especially high myopia are recognised as major public health concerns. Although the prevalence of high myopia in young children is low, 10-20% of high school children in Asia have high myopia, with many still progressing, and one in three patients with high myopia develop visual impairment with age. Most participants in myopia control studies have low and moderate myopia; relatively little is known about myopia control in high myopia. Literature searches were undertaken in MEDLINE and EMBASE to identify publications in English, investigating (Aim 1) the efficacy of myopia control strategies (environmental, pharmacological and optical) in high myopia (≤-6.00 D) and (Aim 2) the complications of high myopia using keywords. Outcomes included change in spherical equivalent refractive error (SE) and/or axial length (AL) to evaluate progression in high myopia. Aim 1: Twelve studies were identified that reported the efficacy of optical and pharmacological (none on environmental) interventions on AL and SE for high myopia control. A statistically significant reduction in progression of SE and AL in high myopes was reported with 1% and 0.5% atropine. Defocus Incorporated Multiple Segment spectacle lenses had lower efficacy in slowing high myopia progression compared to moderate and low myopia. Ortho-K lenses were equally effective in reducing myopia progression in low, moderate and high myopia. Aim 2: Myopic patients have an increased risk of myopic macular degeneration, retinal detachment, cataract and glaucoma, with the risk increasing with the level of myopia. High myopia has significant effects on quality of life, risk of pathological complications and vision impairment. Young children, excluding those with some syndromic associations, who are fast progressing moderate and high myopes require early intervention and close monitoring. Further research investigating the efficacy of myopia control strategies in highly myopic patients, both independently and through combination treatments, are necessary.

Analysis of Refractive Error Changes in Elementary School Children under 13 Years of Age before and after COVID-19 Pandemic: A Hospital-Based Study

Purpose: To analyze changes in refractive error among elementary school children under the age of 13 who visited an outpatient clinic for eye examinations before and after the onset of the COVID-19 pandemic.Methods: A retrospective analysis of medical records was conducted to calculate the spherical equivalent refractive error of the right eye for 3,854 children aged 6 to 12 who attended our ophthalmology department from 2016 to 2023. We analyzed the average refractive error and myopia prevalence by year and subsequently performed a subgroup analysis by dividing the children into two age groups: 6-9 years old and 10-12 years old. To provide insight into long-term trends, data from 4,351 subjects aged 6-12 years from the 4th, 5th (2008-2012), and 7th (2016) Korea National Health and Nutrition Examination Surveys were also analyzed for reference.Results: The mean refractive error for subjects visiting our clinic throughout the study period was -1.51 ± 2.12 D. A trend of increasing myopic values in refractive error was observed from 2017 to 2021, with a more substantial change noted in 2020 compared to other years, though not reaching statistical significance. In the subgroup analysis, the change in refractive error for the 6-9-year-old group was more pronounced in 2020 but did not reach statistical significance, and no specific trend was identified in the 10-12-year-old group. Myopia prevalence exhibited a consistent increase since 2019 in the 6-9 age group, with a higher proportion of moderate myopia in 2020 compared to previous years. Conversely, no distinct trend was observed in the 10-12-year-old group.Conclusions: Although statistical significance was not reached, it appears that the increase in indoor activities due to COVID-19 had an impact on the changes in refractive values for elementary school children, especially in the lower grades of elementary school in 2020.

Analysis of Treatment Discontinuation in Orthokeratology: Studying Efficacy, Safety, and Patient Adherence Over Six Months.

This study aimed to evaluate the efficacy, safety, and participant compliance of orthokeratology treatment for the correction of myopic refractive errors over a six-month prospective study and to define the potential reasons for early treatment discontinuation. A total of 32 participants with low-to-moderate myopia were fitted with the spherical model of corneal refractive therapy (CRT) orthokeratology lenses (Paragon Vision Sciences) and followed over six months, with specific attention to alterations in refractive error, corneal topography, and epithelial thickness. Concurrently, participant feedback and reasons for any treatment discontinuation were documented. Significant changes in refractive error and in corneal topography were observed, with approximately 50% of the refractive error being corrected on the first night of use and 100% by the first two weeks ( P <0.001). Central epithelial thickness experienced substantial thinning, reducing to 15.65±4.49 μm (67.38%) ( P <0.001) after 6 months of lens use. Six participants withdrew from this study for varied reasons, including unmet visual expectations and difficulty adhering to the lens-wearing regimen. Notably, the dropout group exhibited higher baseline low-order aberrations and less prolate corneas than those who persisted with the treatment ( P <0.05). Orthokeratology with CRT is efficacious and safe for the correction of low-to-moderate myopia in adults, but a portion of patients discontinue the treatment in the first 6 months of contact lens wear. Special care should be taken when recommending orthokeratology in patients with higher levels of myopia and corneas with less prolate shape, providing more realistic expectations and even changing to dual axis or more sophisticated designs.

Change in refractive errors with changes in IOL parameters.

This study considered two questions associated with intraocular lens (IOL) power and refraction: (1) Given a refraction with a particular IOL in the eye, what will be the refraction for the IOL or another IOL if located differently with regard to tilt or anterior-posterior position? (2) For a target refraction, what is the power of another IOL if located differently with regard to tilt or position? A thin lens technique was developed to address these questions. For the first question, light was traced through the initial correcting spectacle lens to the cornea, refracted at the cornea, transferred to the position of the initial IOL, refracted at this IOL, transferred to the position of a new IOL (which may be the same IOL but with a different position and/or tilt), refracted backwards through the new IOL, transferred to the cornea and refracted out of the eye to give a new correcting spectacle lens power. For the second question, light was traced through the initial correcting spectacle lens to the cornea, refracted at the cornea, transferred to the position of the initial IOL, refracted at the initial IOL and transferred to the position of a new IOL. Light was also traced through the second correcting spectacle lens, refracted at the cornea and transferred to the position of the second IOL. The difference between the reduced image vergence for the first raytrace and the reduced object vergence for the second raytrace gave the effective power of the second IOL, and from this, the power of the second IOL was determined. Examples are presented for different situations, including a case report.

Redistribution of Epithelium and Stroma and Their Relationship With Corneal Curvature After 1-Month Cessation of Overnight Orthokeratology.

To investigate the changes in the thickness of epithelium and stroma and their relationship with corneal curvature following the cessation of overnight orthokeratology for a period of 1 month. This prospective study consecutively included 20 juveniles (20 right eyes) who had undergone overnight orthokeratology for a minimum of one year and were willing to discontinue the treatment. The study measured and compared epithelial and corneal curvature using optical coherence tomography and Medmont topographer at the first day of cessation and 1 month after cessation. In addition, changes in uncorrected visual acuity and refractive error before and after the cessation of the treatment were analyzed. The study found a significant increase in the thickness of the epithelium in the central 2-mm area after the cessation of the treatment (t = -4.807, P <0.001). Moreover, the stroma in the paracentral area (2-5 mm) and peripheral area (5-6 mm) showed a general thinning trend ( P =0.016, P =0.016). Regarding the correlation analysis, the change in central epithelial thickness (ΔCET) was significantly correlated with the change in paracentral corneal curvature (ΔPCCC) (r=0.610, P =0.007) and the change in peripheral corneal curvature (ΔPCC) (r=0.597, P =0.009). Similarly, the change in central stromal thickness (ΔCST) was significantly correlated with the change in central corneal curvature (ΔCCC) (r=0.500, P =0.035), ΔPCCC (r=0.700, P =0.001), and ΔPCC (r=0.635, P =0.005). The study found that the corneal remodeling induced by orthokeratology was reversible after the cessation of the treatment. Specifically, changes in the epithelium were found to be more prominent in the central area, while changes in the stroma were more pronounced in the paracentral and peripheral areas. In addition, the study established a significant correlation between central corneal remodeling and changes in curvature.

The influence of variations in ocular biometric and optical parameters on differences in refractive error.

To present a paraxial method to estimate the influence of variations in ocular biometry on changes in refractive error (S) at a population level and apply this method to literature data. Error propagation was applied to two methods of eye modelling, referred to as the simple method and the matrix method. The simple method defines S as the difference between the axial power and the whole-eye power, while the matrix method uses more accurate ray transfer matrices. These methods were applied to literature data, containing the mean ocular biometry data from the SyntEyes model, as well as populations of premature infants with or without retinopathy, full-term infants, school children and healthy and diabetic adults. Applying these equations to 1000 SyntEyes showed that changes in axial length provided the most important contribution to the variations in refractive error (57%-64%), followed by lens power/gradient index power (16%-31%) and the anterior corneal radius of curvature (10%-13%). All other components of the eye contributed <4%. For young children, the largest contributions were made by variations in axial length, lens and corneal power for the simple method (67%, 23% and 8%, respectively) and by variations in axial length, gradient lens power and anterior corneal curvature for the matrix method (55%, 21% and 14%, respectively). During myopisation, the influence of variations in axial length increased from 54.5% to 73.4%, while changes in corneal power decreased from 9.82% to 6.32%. Similarly, for the other data sets, the largest contribution was related to axial length. This analysis confirms that the changes in ocular refraction were mostly associated with variations in axial length, lens and corneal power. The relative contributions of the latter two varied, depending on the particular population.

Effectiveness of repeated low-level red light in myopia prevention and myopia control

Background/aimsTo compare the effects of repeated low-level red light (RLRL) treatment on axial length growth and refractive error changes in myopic and premyopic children.MethodsSubjects were assigned randomly to four subgroups:...

Longitudinal Changes in Refractive Development in Highly Hyperopic Children: A 2.6-11.2 Year Follow-up of Preschoolers Diagnosed with High Hyperopia

Purpose This study aims to elucidate the longitudinal refractive and ocular biometric alterations in preschool children with high hyperopia who underwent early interventions. Methods We conducted a retrospective analysis of preschool children diagnosed with high hyperopia at Tianjin Medical University Eye Hospital between 2011 and 2023. Inclusion criteria required an initial examination with cycloplegic refraction, bilateral spherical equivalent power (SE) ≥ +5.00D with a difference <1.00D, a minimum two-year follow-up, and at least three ocular biometric measurements. The annual axial growth rate evaluated emmetropization in highly hyperopic children. We applied Restricted Cubic Spline (RCS) models to explore potential nonlinear relationships between age and spherical equivalent, axial length, corneal curvature, and axial length-to-corneal curvature ratio. Additionally, Mixed-effects models were employed to investigate factors associated with changes in refractive error and axial length. Results The study enrolled 60 eligible subjects, with a median initial diagnosis age of 3.5 years (IQR, 2.8-4.9 years) and a median last visit age of 9.3 years (IQR, 8.1-10.8 years). The average follow-up duration was 5.7 years. RCS analysis revealed notable nonlinear changes in spherical equivalent power, axial length, and axial length-to-corneal curvature ratio, although corneal curvature displayed no statistically significant nonlinear trend. Factors affecting SE changes included the presence of strabismus, the use of cycloplegia, baseline SE, and age. Conversely, changes in axial length solely correlated with baseline axial length and age. Conclusion Highly hyperopic preschool children undergoing early intervention display a marked emmetropization tendency, though most still remain moderately to highly hyperopic, with the progression of refractive changes showing non-uniform patterns with respect to age.

Following prevalence of myopia in a large Swiss military cohort over the last decade: where is the European “myopia boom”?

PurposeMyopia prevalence is increasing globally, with the highest rates found in Asia. Data from European countries is scarce. We aimed to investigate whether the prevalence of myopia is rising in our meridians.MethodsData from male military conscripts for the recruitment period of 2008–2017 were retrospectively analyzed. Year of recruitment, conscripts’ birth year, visual acuity, refractive status (spherical equivalent), and spectacle wear (yes/no) were available.ResultsThe dataset contained data of a total of 355,657 male conscripts, who had been recruited in the years 2008 to 2017. The mean number of conscripts per year was 35,566 (MD = 35,440, SD = 1249), reaching a minimum number of 33,998 conscripts in 2017 and a maximum of 37,594 in 2011. Mean age at recruitment was 19.7 years (MD = 19.0 years, SD = 1.1 years). Overall, the number of conscripts wearing spectacles remained stable over the observation time; on average 29.6% (n = 10,540; MD = 10,472; SD = 492) of conscripts wore glasses at recruitment. Of 21.8% (n = 77,698) of conscripts, data on the refractive status was available: The mean spherical equivalent for both right and left eyes was -2.3D (MD = -2 D, SD = 2.4 D). No decrease in mean spherical equivalent per recruitment year was noted over the observation period. Estimated myopia prevalence reached an average of 27.5% (SD = 0.8%) and did not increase during the observation period.ConclusionIn summary, no change in spherical equivalent refractive errors of male Swiss army conscripts was found for the years 2008–2017. Equally, the percentage of spectacle wearers (MN = 29.6%) and estimated myopia prevalence (MN = 27.5%) did not significantly increase during the observation time.Trial registration: BASEC 2019-00060 (18/01/2019)

Refractive Error Change and Overminus Lens Therapy for Childhood Intermittent Exotropia

Increased myopic shift was found to be associated with 1 year of overminus spectacle treatment for children with intermittent exotropia (IXT). Persistence of myopic shift after discontinuing overminus spectacles is unknown. To compare refractive error change over 3 years in children with IXT originally treated with overminus vs nonoverminus spectacles. This study was an 18-month extension of the Trial of Overminus Spectacle Therapy for Intermittent Exotropia cohort, which previously randomized children aged 3 to 10 years with IXT and baseline spherical equivalent refractive error (SER) between -6.00 diopters (D) and 1.00 D to overminus spectacles (-2.50 D for 12 months, -1.25 D for 3 months, and nonoverminus for 3 months) or nonoverminus spectacles. Children were recruited from 56 sites from July 2010 to February 2022. Data were analyzed from February 2022 to January 2024. After trial completion at 18 months, participants were followed up at 24 and 36 months. Treatment was at investigator discretion from 18 to 36 months. Change in SER (cycloplegic retinoscopy) from baseline to 36 months. Of 386 children in the Trial of Overminus Spectacle Therapy for Intermittent Exotropia, 223 (57.8%) consented to 18 months of additional follow-up, including 124 of 196 (63.3%) in the overminus treatment group and 99 of 190 (52.1%) in the nonoverminus treatment group. Of 205 children who completed 36-month follow-up, 116 (56.6%) were female, and the mean (SD) age at randomization was 6.2 (2.1) years. Mean (SD) SER change from baseline to 36 months was greater in the overminus group (-0.74 [1.00] D) compared with the nonoverminus group (-0.44 [0.85] D; adjusted difference, -0.36 D; 95% CI, -0.59 to -0.12; P = .003), with 30 of 112 (26.8%) in the overminus group having more than 1 D of myopic shift compared with 14 of 91 (15%) in the nonoverminus group (risk ratio, 1.8; 95% CI, 1.0-3.0). From 12 to 36 months, mean (SD) myopic shift was -0.34 (0.67) D and -0.36 (0.66) D in the overminus and nonoverminus groups, respectively (adjusted difference, -0.001 D; 95% CI, -0.18 to 0.18; P = .99). The greater myopic shift observed after 1 year of -2.50-D overminus lens treatment remained at 3 years. Both groups had similar myopic shift during the 2-year period after treatment weaning and cessation. The risk of myopic shift should be discussed with parents when considering overminus lens treatment. ClinicalTrials.gov Identifier: NCT02807350.

Altering optical zone diameter, reverse curve width, and compression factor: impacts on visual performance and axial elongation in orthokeratology

PurposeTo investigate the effects of modifications in back optical zone diameter (BOZD), reverse curve width (RCW), and compression factor (CF) on refractive error changes and axial elongation in myopic children undergoing orthokeratology (ortho-k) over a 12-month period. MethodIn this retrospective study, data from 126 myopic children undergoing ortho-k fitting were analyzed. Subjects were categorized into four distinct groups based on lens design parameters: Group A (BOZD 6.0 mm, RCW 0.6 mm, CF 0.75 D); Group B (BOZD 6.0 mm, RCW 0.6 mm, CF 1.25 D); Group C (BOZD 5.4 mm, RCW 0.9 mm, CF 1.25 D); and Group D (BOZD 5.0 mm, RCW 1.1 mm, CF 1.25 D). The study evaluated uncorrected visual acuity (UCVA), corneal topography, and axial length (AL) at intervals, using Linear Mixed Models (LMMs) for time-based changes, and ANOVA or Kruskal-Wallis tests for group differences in AL elongation. A multivariable regression analysis identified factors independently associated with AL elongation. ResultsWithin the first day and week, all four groups displayed significant improvements in UCVA and alterations in corneal curvature, which subsequently stabilized. Although UCVA variations between groups were subtle, Group D had less corneal curvature change than Groups A and B initially and exhibited significantly less AL elongation after one year. No significant difference in corneal curvature change or AL elongation was observed between Group C and the other groups. Multiple regression analysis indicated that older baseline age, greater baseline spherical equivalent refractive error, and smaller BOZD were associated with less AL elongation. ConclusionThe study reveals a positive correlation between BOZD and axial length growth over the 12-month period. A pure 0.5 D CF increment demonstrates a nonsignificant impact. This study provides new ideas into optimizing the parameters of ortho-k lenses.

Prescription eyeglasses as a forensic physical evidence: Prediction of age based on refractive error measures using machine learning algorithm.

Refractive errors (RE) are commonly reported visual impairment problems worldwide. Previous clinical studies demonstrated age-related changes in human eyes. We hypothesized that the binocular RE metrics including sphere and cylinder power, axis orientation, and interpupillary distance (IPD) can be used for forensic age estimation of an unknown individual. RE data of both eyes were collected from the clinical optometric exams and prescription glasses of 2027 Egyptian individuals aged between 2 to 93 years. The differences between age groups as well as sides, and sexual dimorphism were explored. Two modeling methods were compared: multiple and stepwise linear regression (LR) versus machine learning Regression Forest (RFM). Data were apportioned into training and test datasets with a ratio of 80/20. The results showed significant differences among the age groups in each eye for all variables. Stepwise LR improved the results over models based on the one-sided lens due to selection of IPD in addition to the left and right axis, and left sphere as independent variables. For the RFM, the left axis and IPD were the most important features. RFM outperformed LR in terms of accuracy and root mean squared error (RMSE). The estimated age within ±10 years showed 81.4% accuracy rate and RMSE = 8.9 years versus 38.5% accuracy rate and RMSE = 17.99 years using RFM and stepwise LR, respectively, in the test set. The current study upholds the significance of the age-related changes of refractive error in formulating alternative forensic age estimation models when standard methods are unavailable.

Synchronous myopia development induced by bilateral form deprivation in chicks

Form deprivation (FD) is a widely employed experimental paradigm, typically used to induce unilateral myopia in animal models. This model is weakened by potential influence upon the FD eye from vision in the freely-viewing contralateral eye, which could be eliminated by imposing FD in both eyes; but while a few previous studies have explored the feasibility of inducing bilateral FD in chicks, substantial discrepancies in treatment outcomes were noted. Consequently, this study aimed to establish a bilateral FD myopia model in chicks, with validation by investigating the associated ocular growth patterns, feeding, and social behavior. Six-day-old chicks were treated with bilateral (n = 21) or unilateral (n = 10) FD for 12 days; the fellow untreated eyes in the unilateral FD group served as controls. Refractive error, corneal power, and ocular axial dimensions were measured at 4-day intervals after the onset of form deprivation, with a Hartinger refractometer, a custom-made videokeratography system, and a high-resolution A-scan ultrasonographer, respectively. Body weight was monitored to assess the chick's physical development. Our results showed that birds treated with bilateral FD grew as robustly as the unilaterally form-deprived chicks, with similar or slightly heavier body weights and mortalities. Unilateral FD induced significantly higher myopia in the treated eye, with stronger corneal power, deeper anterior and vitreous chambers, and longer axial length. Moreover, either bilaterally or unilaterally FD eyes developed similar refractive error (bilateral FD, left: −28.03 ± 9.06 D, right: −28.44 ± 9.45 D; unilateral FD: −29.48 ± 8.26 D) and ocular biometric changes; but choroidal thickness was thicker in bilaterally FD eyes, rather than thinner as in unilaterally FD eyes. In addition to the highly synchronized (symmetrical, parallel) development reported previously in bilateral FD, we found in this study that the correlations between bilaterally form-deprived eyes were highest for ocular biometric parameters directly contributing to myopia development, including corneal power (r = 0.74 to 0.93), anterior chamber depth (r = 0.60 to 0.85), vitreous chamber depth (r = 0.92 to 0.94), and axial length (r = 0.90 to 0.96). The remarkably synchronized growth pattern confirmed the feasibility of the bilateral FD paradigm for future research on myopia.