Refractive Change Research Articles

Refractive Changes and Corneal Thickness in Healthy Mountaineers at High Altitude: The Korzhenevskoi Experience (7105 m).

The purpose of this study was to investigate the effect of hypoxia and hypobaric conditions on refraction and central corneal thickness on healthy corneas during an ascent without oxygen supplementation above 7000 m (23 000 ft). Twelve multinational mountaineers were included in a prospective observational cohort study during an expedition to the Korzhenevskoi Peak (7105 m). The two patients excluded from the study had a history with keratoconus or were current wearers of rigid contact lenses. None had a history of refractive surgery or ocular disease. The central corneal thickness (CCT), the oxygen saturation, and the refraction have been recorded for each patient using portable equipment. The highest measurement has been taken at 6356 m of altitude which is the highest ophthalmologic measurement ever done. Longitudinal analysis revealed a significant increase of CCT during altitude exposure (CCTbaseline = 542± 36 μm; CCTC3 = 633 ± 30 μm) due to stromal edema reversible upon descent. The amount of decrease in oxygen saturation paralleled the increase in CCT. The refraction measurements showed a myopic shift (-1.14D) with the altitude (RBaseline = -0.41 ±2.25D; RC3 = -1.55 ± 2.41D P < 0.05). Significant stromal edema was found during exposure to high altitude in healthy mountaineers. This is due to hypoxia and decreased atmospheric pressure leading to a deficiency of adenosine triphosphate. A significant and clinically relevant myopic shift, due to the stroma edema, appears above 6500 m which can explained the blurry far vision in high altitude for mountaineers without oxygen supplementation.

Efficacy and Safety of Different Atropine Regimens for the Treatment of Myopia in Children

Additional data are required regarding atropine treatment regimens for control of myopia progression. To investigate the efficacy and safety of different atropine regimens for myopia in children. This was a secondary analysis of the 3-year results of the 24-Month Myopia Outcome Study of Atropine in Children (MOSAIC) trial, called the MOSAIC2 trial. The MOSAIC trial was an investigator-led, double-masked, randomized clinical trial of different atropine concentrations and regimens. The MOSAIC2 study took place at the Centre for Eye Research Ireland, in Dublin, Ireland, and included children and adolescents with myopia from the MOSAIC trial. Data analysis was conducted from November 2023 to February 2024. Participants were randomly assigned to the following cohorts: group 1, nightly placebo for 2 years then 0.05% atropine eye drops for 1 year and group 2, nightly 0.01% atropine eye drops for 2 years then rerandomization to placebo nightly, tapering placebo, or tapering of 0.01% atropine eye drops for 1 year. Observed changes in cycloplegic spherical equivalent refraction and axial length from month 24, or baseline, to month 36. A total of 199 children with myopia (mean [SD] age, 13.9 [2.4] years; 121 female [60.8%]) of the 250 children and adolescents from the MOSAIC trial were included in the MOSAIC2 trial analysis. Of 83 participants assigned to group 1, 66 (79.5%) reconsented to year 3, and 61 (73.5%) completed the trial. Of 167 participants assigned to group 2, 133 (79.6%) continued to year 3, and 121 (72.5%) completed the trial (0.01% atropine, then nightly placebo: n = 31 and n = 29 [93.5%]; 0.01% atropine, then tapering placebo: n = 29 and n = 25 [86.2%]; 0.01% atropine then tapering 0.01% atropine: n = 73 and n = 67 [91.8%], respectively). Compared with the group taking placebo then 0.05% atropine, the combined atropine then placebo groups had more spherical equivalent progression (adjusted difference, -0.13 diopters [D]; 95% CI, -0.22 to -0.04 D; P = .01) and axial elongation (adjusted difference, 0.06 mm; 95% CI, 0.02-0.09 mm; P = .008), and the group taking 0.01% atropine then tapering 0.01% atropine had more axial elongation (adjusted difference, 0.04 mm; 95% CI, 0.009-0.07 mm; P = .04). In the group taking placebo then 0.05% atropine, 15% (n = 10) and 8% (n = 5) reported blurred near vision and photophobia, respectively, during year 3, compared with 3% (n = 2) and 0%, respectively, in the group taking 0.01% atropine then tapering 0.01% atropine, and no reports in both placebo groups. Despite more adverse events, participants using 0.05% atropine during year 3 had no differences in treatment completion rates and exhibited 0.13-D less myopia progression and 0.06-mm less axial elongation, compared with participants using placebo, supporting consideration of treatment as given to the group taking 0.05% atropine in this European population. isrctn.org Identifier: ISRCTN36732601.

Evaluation of Auricular Acupressure on Myopia Prevention among Children Aged 6–12 Years with Pre-Myopia in China: Study Protocol of a Prospective Multi-Center Randomized Controlled Trial

Background: The increasing prevalence of myopia among Chinese children and adolescents, especially at younger ages, has emerged as a significant concern in recent years. Pre-myopia is a key period for myopia prevention and control in children and adolescents. Previous studies suggested auricular acupressure (AA) therapy might offer a viable approach to prevent and slow down myopia progression. Nonetheless, these studies lack robust, high-quality, large-scale, multi-center evidence to conclusively support such assertions. The purpose of this research is to evaluate the efficacy, safety, and economic benefits of AA therapy in preventing myopia in Chinese children aged 6–12 years with pre-myopia. Methods: The single-blind, multi-center, parallel-group, randomized controlled trial will involve 318 pre-myopic children from 20 different centers across China. After recruitment, these participants will be randomly assigned to two groups (the AA group and the control group) at a 1:1 ratio. The AA group will receive auricular point sticking therapy along with health education for a period of 24 weeks, while the control group will be provided the sham AA treatment and routine health education. The assessments of outcomes will be conducted at the start of this study, and then after 4, 8, 12, and 24 weeks. The primary outcome is the change in spherical equivalent refraction at various follow-up times. The secondary outcomes include the number of myopia cases, uncorrected visual acuity, axial length, corneal curvature radius, accommodation amplitude, retinal and choroidal thickness, and eye behavior management. In addition, the cost-effectiveness analysis will be used as the evaluation index for economic assessment. Discussion: The results of this research will provide evidence on the efficacy, safety, and economic benefits of AA therapy in preventing myopia among children aged 6–12 years with pre-myopia in China.

Real-world outcomes on myopia management efficacy of diverse segmented defocus optics (DSDO) and defocus incorporated multiple segments (DIMS) spectacle lenses in Chinese children: An initial 12-month prospective clinical study.

To investigate the 12-month effectiveness of Diverse Segmented Defocus Optics (DSDO) and Defocus Incorporated Multiple Segments (DIMS) spectacle lenses in a real-world clinical population in myopic and pre-myopic Chinese children. About 364 subjects prescribed DSDO or DIMS were enrolled. Axial length (AL) and cycloplegic spherical equivalent refraction (SER) changes over 12 months were measured. The subjects were further divided into age sub-group (6-9; 10-14) and SER sub-group (+0.75D≤SER<-0.50D; -0.50D≤SER<-2.00D; -2.00D≤SER<-4.00D; SER≤-4.0D). Contrast sensitivity and visual experience were also reported. The rate of myopia progression was compared with historical single-vision spectacles (SVS) lenses data to evaluate the effectiveness of the regime. 317 subjects were analyzed. At 12-month, AL changes in the DSDO and DIMS group were 0.16±0.16 mm and 0.21±0.22 mm, respectively (P = 0.0202). DSDO spectacle lenses had better control effect in +0.75D≤SER<-0.50D and SER≤-2.0D sub-groups. The proportion of participants had no greater than 0.20 mm AL elongation was 65.00% and 55.41% of in DSDO and DIMS group separately. Myopia control effect in DSDO group was 47%-69% and 33%-62% in DIMS group compared to historical SVS lenses. Both DSDO and DIMS spectacle lenses retarded AL elongation. DSDO showed more stable myopia control effect comparing to DIMS, especially in groups of SER≤-2.0D sub-groups and older patients. DSDO showed initial potential myopia prevention effect in pre-myopic children compared with historical SVS lenses data. However, the small sample and no control group in pre-myopes of this study are key limitations. Further research is needed to confirm and understand DSDO's role for pre-myopic children.

Effects of strabismus surgery on cornea

Background Strabismus is a common disorder that is mostly treated surgically. Extraocular muscle surgery may induce refractive and corneal topographic changes. Aim To study the effect of horizontal strabismus surgery on corneal topography Patients and methods This prospective interventional randomized study was carried out on 20 patients aged from 5 to 30 years old diagnosed with horizontal strabismus who did not undergo any ocular surgery before. They were divided into four groups. We did lateral rectus recession in the first group, lateral rectus resection in the second group, medial rectus resection in the third group, and medial rectus recession in the fourth one. We compared the spherical equivalent and the corneal topographic parameters (K1, K2, the power and the axis of the astigmatism) preoperative, at 1 month postoperative, and at 6 month postoperative. Results There was myopic shift in the spherical equivalent in all groups and it was more significant after recession surgery. There was a statistically significant change in K1, K2, and astigmatism power after recession of medial and lateral recti muscles which persisted till the postoperative sixth month. The change after resection of medial and lateral recti muscles was insignificant. The change in the axis was insignificant in all groups. Conclusions Recession surgery of medial or lateral recti has more effect on refraction and corneal topography than resection. Horizontal strabismus surgeries induce a significant myopic shift in the spherical equivalent and do not induce a significant change in the axis.

Changes in relative peripheral refraction after implantable collamer lenses implantation.

This study aimed to measure the changes in refraction difference value (RDV) in different parts of the retina before and after implantable collamer lenses (ICL) surgery. Prospective study. This study included 40 eyes of 40 patients who underwent ICL implantation for myopia. RDV measurements were taken across several ranges: 0°-15°, 15°-30°, 30°-45°, and 45°-53°, and categorized into four sectors: superior (RDV-S), inferior (RDV-I), temporal (RDV-T), and nasal (RDV-N), along with total RDV (TRDV). Measurements were taken preoperatively, and at one week and one month postoperatively. TRDV, RDV beyond 15° eccentricity, and RDV-S, RDV-I, RDV-T, and RDV-N were significantly increased postoperatively. The one-week and one-month follow-up of RDVs had no significant differences. Significant differences in the increments were observed among RDV-15, RDV-15-30, RDV-30-45, and RDV-45-53 both at one-week and one-month follow-up. Similarly, there were significant differences in the increments among RDV-S, RDV-I, RDV-T, and RDV-N both at one-week and one-month follow-up. TRDV, RDV-30-45, RDV-45-53, RDV-S, RDV-T, and RDV-N showed significant differences in the variation preoperatively and postoperatively between the high (SE > -9.00 D) and ultra-high (SE ≤ -9.00 D) myopia groups. Peripheral refraction showed a hyperopic defocused state that can stabilize in the early postoperative period after ICL implantation. The variation in the hyperopic defocused shift in peripheral refraction increased more in the regions farther from the central retina. The temporal regions exhibited the most changes. WHAT IS KNOWN : Myopia is generally believed to stabilize after adulthood, but some individuals continue to experience myopia progression, accompanied by axial length elongation. Traditional spectacle lenses correct myopia by focusing light on the fovea but may introduce peripheral hyperopic defocus, which is thought to contribute to myopia progression. ICL surgery effectively corrects high degrees of myopia and astigmatism. Previous studies have demonstrated the safety and efficacy of ICL in addressing central refractive errors, but peripheral refraction changes post-surgery have not been well-explored. ICL surgery increased peripheral hyperopic defocus while correcting central refractive error, with significant changes in peripheral refraction observed from the preoperative to postoperative one-week and one-month.. After ICL implantation, a hyperopic shift was observed in peripheral areas, with RDV values within 15° of the central retina appearing emmetropic and increasing hyperopic defocus noted moving away from the posterior pole. Peripheral refraction stabilized approximately one week after ICL surgery, with no significant differences observed between the one-week and one-month follow-ups, indicating that stability in peripheral refraction is typically achieved within this timeframe.

Quantitative analysis of retinal vascular parameters changes in school-age children with refractive error using artificial intelligence.

To quantitatively analyze the relationship between spherical equivalent refraction (SER) and retinal vascular changes in school-age children with refractive error by applying fundus photography combined with artificial intelligence (AI) technology and explore the structural changes in retinal vasculature in these children. We conducted a retrospective case-control study, collecting data on 113 cases involving 226 eyes of schoolchildren aged 6-12 years who attended outpatient clinics in our hospital between October 2021 and May 2022. Based on the refractive spherical equivalent refraction, we categorized the participants into four groups: 66 eyes in the low myopia group, 60 eyes in the intermediate myopia group, 50 eyes in the high myopia group, and 50 eyes in the control group. All participants underwent a series of examinations, including naked-eye and best-corrected visual acuity, cycloplegic spherical equivalent refraction, intraocular pressure measurement, ocular axial measurement (AL), and color fundus photography. Using fundus photography, we quantitatively analyzed changes in the retinal vascular arteriovenous ratio (AVR), average curvature, and vascular density with AI technology. Data were analyzed using the χ2 test and one-way analysis of variance. The AVR in the low myopia group, moderate myopia group, high myopia group, and control group were 0.80 ± 0.05, 0.80 ± 0.04, 0.76 ± 0.04, and 0.79 ± 0.04, respectively, and the vessel densities were 0.1024 ± 0.0076, 0.1024 ± 0.0074, 0.0880 ± 0.0126, and 0.1037 ± 0.0143, respectively The difference between the AVR and vascular density in the high myopia group was statistically significant compared to the other three groups (p < 0.05). Linear correlation analysis showed a strong negative correlation between the spherical equivalent refraction and the ocular axis (r = -0.874, p < 0001), a moderate positive correlation between the spherical equivalent refraction and the vascular density (r = 0.527, p < 0001), and a moderate negative correlation between the ocular axis and the vascular density (r = -0.452, p < 0001). Schoolchildren with high myopia showed a decreased AVR and decreased vascular density in the retinal vasculature. The AVR and vascular density may be early predictors of myopia progression.

Postoperative corneal remodeling after corneal allograft intrastromal ring segment (CAIRS) implantation for keratoconus: An OCT study.

To demonstrate corneal remodeling after corneal allograft intrastromal ring segment (CAIRS) with an anterior-segment optical coherence tomography (AS-OCT). A prospective observational single-center study. This observational study included keratoconus patients who underwent CAIRS implantation into a stromal tunnel. Topographical, refractive, and visual changes were obtained from the patient records. Epithelial thickness (ET), anterior stromal thickness (AST), allograft corneal ring thickness (ACRT), and posterior stromal thickness (PST) were measured on the first day and 1, 3, 6, and 12 months postoperatively using AS-OCT. The study included 35 eyes of 27 patients with advanced keratoconus. The mean keratometry decreased from 48.26 ± 4.78 D to 44.50 ± 4.42 D at 1-year postoperatively (P = 0.004), mean corrected distance visual acuity increased from 0.29 ± 0.18 to 0.70 ± 0.24 (P < 0.001), and spherical equivalent (SE) decreased from -6.94 ± 4.32 D to -1.44 ± 4.44 D (P < 0.001). The mean AST decreased by 17.39 ± 5.78 μm in the postoperative 1st month compared to 1st day after surgery (P = 0.040). No statistically significant variations were observed in AST after the first month. There was no statistically significant difference in the mean ET, ACRT, and PST measurements between follow-up times. Significant negative correlations were found between SE change and ET (r = -0.543, P = 0.023) and between K1 change and ACRT (r = -0.548, P = 0.008). CAIRS is an effective treatment method to improve visual acuity and keratometry measurements and does not cause significant changes in graft thickness or recipient corneal epithelial and stromal thicknesses during the 1-year follow-up period. The observed correlations between SE, keratometry, and corneal thickness suggest that epithelial and stromal remodeling play crucial roles in postoperative outcomes of CAIRS.

Refractive Astigmatism Consistency Pre- and Post-Cycloplegia in Pediatric Population

Background: Cycloplegic refraction is crucial in pediatric eye assessments. While spherical refraction changes due to cycloplegia are well-documented, astigmatic alterations remain unclear. This study assessed the agreement between spherical and astigmatic refraction pre- and post-cycloplegia. Methods: We enrolled 96 patients (mean age: 12.5 ± 2.4 years), including 35 myopes, 30 emmetropes, and 31 hyperopes. Pre- and post-cycloplegia autorefraction and keratometry (Myopia Master) were conducted using 1% cyclopentolate. Ocular residual astigmatism (ORA) was calculated as the difference between refractive and keratometric astigmatism. Astigmatism was analyzed using Fourier analysis (J0 and J45). Results: Cycloplegia resulted in a more positive spherical equivalent (SE) (+0.80 D), with myopes showing the smallest (+0.38 D) and hyperopes showing the highest variation (+1.47 D) in SE. With-the-rule (WTR) astigmatism predominated in the refractive and keratometric measurements, while ORA was against-the-rule (ATR). Cycloplegia shifted the refractive J0 (+0.06 D) towards more WTR and decreased ORA J0 (+0.05 D). No effect was observed in the J45 component. About 25% of patients exhibited astigmatism changes above 0.25 D, with refractive J0 variation being positively correlated with accommodation relaxation (0.044 D per D of relaxation). Conclusion: Cycloplegia induces clinically significant changes in the spherical component, but minimal variations in astigmatic components, predominantly in hyperopic eyes, likely reflecting alterations in crystalline lens anatomy.

Efficacy of spectacle lenses specifically designed for myopia control: systematic review and meta-analysis.

To investigate the efficacy of spectacle lenses designed to control myopia progression in individuals under 18 years old, focusing on changes in spherical equivalent refraction (SER), axial length (AL) and relative peripheral refraction (RPR). A systematic review was conducted according to Prisma guidelines. Databases searched included PubMed, Embase, and Scopus, covering studies from the last six years without language restrictions. Studies were included based on specific criteria, and data were extracted and analysed using the metafor package in R. Separate meta-analyses were conducted for SER and AL at 12- and 24-month follow-ups, using random-effects models. RPR information was synthesized without meta-analysis. Out of the 796 studies screened, 21 were included in the review, with 17 selected for the meta-analysis, comprising a total of 6,175 patients. At 12 months, the intervention group showed a significant reduction in SER (d+ = -0.281, p < .0001) and AL (d+ = -0.155, p < .0001) compared to the control group, where d + is the pooled mean effect size estimate. However, at 24 months, no significant differences were observed in SER (d+ = -0.385, p = .067) or AL (d+ = -0.272, p = .137) between groups. Sensitivity analyses confirmed these findings, and publication bias was minimal. Regarding RPR, the results are limited and differ among model lenses. Spectacle lenses designed to control myopia progression show short-term benefits, significantly reducing SER and AL at 12 months. However, their long-term efficacy remains uncertain, with no significant differences observed at 24 months. Further research is needed to understand treatment response factors and evaluate the long-term efficacy and safety of these lenses in myopia management.

Effect of bifocal soft contact lenses in combination with instillations of the combined drug (Phenylephrine 5% and Tropicamide 0.8%) on the anatomical and functional parameters of the eyes and progression of myopia in pediatric patients

AIM: The study aimed to assess the influence of combined optical and pharmacological effects on the anatomical and functional parameters of the eyes and changes in refraction in pediatric patients with progressive myopia. MATERIAL AND METHODS: Bifocal soft contact lenses (BSCL) Prima BIO Bifocal were prescribed to 43 pediatric patients. At the start of the study, the average age of the children was 10.42±0.26 years, and the average myopia was 3.43±0.19 D. The effect of a combination of optical and medicinal products on the visual apparatus of children was evaluated, namely, bifocal SCLs that form peripheral myopic defocus and instillations of a combined drug containing 0.8% tropicamide and 5% phenylephrine. The combined eye drops, which contained 0.8% tropicamide and 5% phenylephrine, was prescribed once a day at night for 1 month to 23 pediatric patients after wearing the lenses for 1 month (group 1). In group 2 (n=20), patients did not receive any additional treatment, except for optical exposure. RESULTS: The habitual tone of accommodation (HTA) slightly increased after 1 month of using BSCL. In group 1, the HTA decreased to the initial level after 6 and 12 months, whereas it remained high in group 2. Over the year, refraction increased by 0.39 D in group 1 and 0.18 D in group 2 (p 0.05). The annual progression gradient decreased by 2.3 times in group 1 and 5.2 times in group 2. Over the year, the anteroposterior axis increased by 0.13 mm in group 1 and 0.05 mm in group 2. Choroidal thickness increased by 19.09 and 24.77 µm, relative accommodation reserve increased by 0.98 and 1.24 D, and the accommodation amplitude increased by 1.28 and 1.05 D, respectively. CONCLUSION: BSCLs contribute to the reduction of the annual gradient of progression (AGP) and increase in accommodation and choroidal thickness. Instillations of the drug while using BSCL help reduce the habitual tone of accommodation (HTA).

Phacovitrectomy vs. consecutive vitrectomy for idiopathic macular holes: short and long-term outcomes and OCT image quality assessment

PurposeTo compare short- and long-term anatomical, functional, and refractive outcomes between combined phacovitrectomy (PVS) and consecutive vitrectomy (CVS) for idiopathic macular holes (MHs). Also, to evaluate the role of preoperative optical coherence tomography (OCT) image quality in guiding surgical selection.MethodsThis retrospective study analyzed 183 phakic MH eyes operated between 2012 and 23, with patients divided into PVS and CVS groups. Demographic and ocular data, MH features, visual acuity (VA), refraction changes and postoperative outcomes, and follow-up details were collected. Pre- and post-operative OCT scans were evaluated for MH characteristics, OCT image quality, and surgical outcomes at short-term (≤ 3 months) and long-term (≥ 5 years) intervals.ResultsThe study included 144 eyes in PVS group and 39 in CVS group. Median follow-up duration was 16 months for PVS group and 72 months for CVS group (p < 0.001). Both groups showed significant VA improvements and comparable MH closure rates at short-term follow-up. However, CVS group had significantly better postoperative VA at short-term (p = 0.001) and long-term (p = 0.017) intervals. The preoperative OCT quality index did not significantly differ between groups and was ineffective in assessing cataract grade or guiding surgical decisions. Both groups experienced a myopic refractive shift, with a higher magnitude in the PVS group (p = 0.04). Postoperative complications were similar between the groups.ConclusionCVS achieves better long-term VA than PVS following MH repair, despite similar anatomical outcomes. Preoperative OCT quality index is not effective for guiding surgical decisions, and careful refractive planning is essential, especially for PVS patients, to address postoperative myopic shifts.Clinical trial registration numberNot applicable.

Refractive change at 5 years in the Toddler Aphakia and Pseudophakia Study (TAPS).

To report refractive change at age 5 years in pseudophakic eyes operated before 2 years of age. Retrospective case series at 10 Infant Aphakia Treatment Study (IATS) sites. Children who underwent cataract surgery with primary intraocular lens placement during the IATS enrollment years, including infants 1 to <7 months of age with bilateral cataract and all children 7-24 months of age, regardless of laterality. Change in spherical equivalent refractive error (diopters[D]) was calculated from 1-month postoperatively to 5 years of age and compared for unilateral and bilateral (first eye only) cases, and for 1 to <7 vs 7-24 months at surgery. Refractive change (D) from surgery to age 5 years. 96 children were included: 50 unilateral (surgery 7-24 months of age); 46 bilateral (n=20, surgery at 1 to <7 months of age; n=26, at 7-24 months). Median refractive change was significantly greater for bilateral pseudophakic eyes operated at 1 to <7 months (7.50 D, range 2.5 to 15 D) vs. 7-24 months (1.94 D, range -1.88 to 7.75 D; P<0.001). For children aged 7-24 months at lensectomy, median change was similar between unilateral (3.25D, range -1.75 to 13.5 D) vs. bilateral cases (1.94D, range 1.88 to 7.75 D; P=0.053). By age 5 years, none of the pseudophakic eyes 1 to <7 months at surgery had <2.5D myopic shift, but 55% of bilateral and 25% of unilateral cases 7-24 months at surgery had < 2.5D myopic shift. Greater magnitude and variability in refractive change was found in pseudophakic eyes operated at 1 to <7 months and for unilateral cases, which should be considered when choosing IOL power and initial post-operative target refraction for infants and toddlers.

Dynamics of Myopia Progression in Ghana-Evidence From Clinical Practice: A Retrospective Cohort Study.

To investigate the pattern of progression of myopia among a Ghanaian clinical cohort. A retrospective cohort analysis of a clinical data set of all healthy myopic participants attending a tertiary eye care center was performed. Participants' biennial refraction examinations were tracked for refractive changes 4 years after the date of the first visit. This covered the period from January 2015 to December 2019. Myopia progression was defined as a difference in spherical equivalent between consecutive biennial visits equal to, or greater than -0.50 D of myopia. The medical records of 169 myopic participants were reviewed, with the majority (53.8%) being female. Most of the participants (51.4%) were younger than 36 years, and at the end of the study period, 96 participants (56.8%), who made up the majority, showed progression of myopia Univariate regression revealed that the 36-59-year-old age range is associated with a 60% [cOR = 0.40, 95% CI: -0.17, 0.97; p = 0.04] reduced likelihood compared to those belonging to the 0-17-year-old age group, and the Mole-Dagbon ethnicity is associated with an almost fourfold [cOR = 3.80; 95% CI: -1.40, 10.316; p = 0.01] increased likelihood of experiencing myopia progression compared to those of Ga-Adangbe ethnicity. Multivariate regression revealed that the Mole-Dagbon ethnicity is associated with an increased likelihood of experiencing myopia progression 4 years after their initial visit [aOR = 3.49; 95% CI: -1.27, 9.63; p = 0.02] compared to those of Ga-Adangbe ethnicity. Our study provides important insights into myopia progression in Ghana, with findings that are consistent with global trends. The association of myopia progression with age, place of residence, degree of myopia, and ethnicity highlights the need for tailored interventions to manage this growing public health concern in African populations.

Retrieval of refractivity fields from GNSS tropospheric delays: theoretical and data-based evaluation of collocation methods and comparisons with GNSS tomography

This paper focuses on the retrieval of refractivity fields from GNSS measurements by means of least-squares collocation. Collocation adjustment estimates parameters that relate delays and refractivity without relying on a grid. It contains functional and stochastic models that define the characteristics of the retrieved refractivity fields. This work aims at emphasizing the capabilities and limitations of the collocation method in modeling refractivity and to present it as a valuable alternative to GNSS tomography. Initially, we analyze the stochastic models in collocation and compare the theoretical errors of collocation with those of tomography. We emphasize the low variability of collocation formal variances/covariances compared to tomography and its lower dependence on a-priori fields. Then, based on real and simulated data, we investigate the importance of station resolution and station heights for collocation. Increasing the network resolution, for example, from 10 to 2 km, results in improved a-posteriori statistics, including a 10% reduction in the error statistic for the retrieved refractivity up to 6 km. In addition, using additional stations at higher altitudes has an impact on the retrieved refractivity fields of about 1 ppm in terms of standard deviation up to 6 km, and a bias reduction of more than 3 ppm up to 3 km. Furthermore, we compare refractivity fields retrieved through tomography and collocation, where data of the COSMO weather model are utilized in a closed-loop validation mode to simulate tropospheric delays and validate the retrieved profiles. While tomography estimates are less biased, collocation captures relative changes in refractivity more effectively among the voxels within one height level. Finally, we apply tomography and collocation to test their capabilities to detect an approaching weather front. Both methods can sense the weather front, but their atmospheric structures appear more similar when the GNSS network has a well-distributed height coverage.

Refractive changes in children in the Chicago area during the COVID-19 pandemic: a retrospective observational study

BackgroundRemote learning during the COVID-19 pandemic caused behavioural changes such as increased screen time and decreased outdoor time. This study aimed to investigate myopia progression in children during the COVID-19...

Correlation between repeated low-level red light-induced afterimage and axial changes in myopia control

PurposeTo explore the correlation between afterimages induced by repeated low-level red light (RLRL) and changes in refraction. MethodPatients who used RLRL for myopia control from 2023.02 to 2024.06 were included in this study. The afterimage appeared on a gray background (RGB 217,217,217; Lab 87,0,0). Afterimage color was recorded with CIELAB nomenclature (R, G, B; L, a, b), and afterimage duration (T) was recorded in seconds. Axial length (AL) and axial length-to-corneal radius ratio (AL/CR) were followed up at 1-, and 3-month. Participants were divided into groups based on a = 0 for GroupR (a>0,red bias in afterimage) and GroupG (a<0,green bias in afterimage); b = 0 for GroupY (b>0,yellow bias in afterimage) and GroupB (b<0,blue bias in afterimage), and T = 50.50 for GroupS (T<50.50,shorter afterimage duration) and GroupL (T>50.50,longer afterimage duration). ResultsA total of 52 participants were included in this study, with an age of 9.25 (1.75) years, 27 (51.92 %) males. The T median (P25, P75) was 50.50 (31.25,85.50) s. After RLRL treatment, divided by a = 0, GroupG showed significantly more shortening in the AL changes than GroupR at 1month and 3months (both P<0.05) and the AL/CR changes difference was not significant. Divided by T = 50.50, GroupS showed significantly greater shortening in the AL changes than GroupL at only 1month (P<0.05) and the AL/CR changes difference was not significant. Divided by b = 0, the difference between GroupY and GroupB was not statistically significant (P>0.05). ConclusionThe change of AL after RLRL treatment showed a correlation to the afterimage. Patients with green afterimage and shorter afterimage duration have a better AL shortening after RLRL treatment. Afterimage may serve as a biomarker for more effective myopia control.

POSSIBILITIES OF AUTOREFKERATOMETRY

In modern ophthalmology, autorefkeratometry has long become a routine diagnostic study, without which it is impossible to imagine any examination. Computerized autorefkeratometers allow you to obtain a huge amount of information about the condition of the patient’s eye in a short time. At the same time, the information obtained is not always subjected to in-depth analysis.Refractometry data should be compared with keratometry data, compared with the indicators of the paired eye, and evaluate, if possible, the dynamics of changes and their tendency. Comparison of the obtained parameters with the average statistical indicators and the age norm make it possible to establish the presence of pathology that does not belong to the field of refractive errors. Thus, the occurrence of anisometropia with similar keratometry parameters suggests opacity of the lens or vitreous pathology. Direct astigmatism is typical for young people, and oblique or reverse astigmatism is typical for patients 65+. A shift in the irido-lens diaphragm is always accompanied by a change in refraction and its instability. Keratectasias are characterized by high variability in refraction and keratometry data, while sometimes maintaining high visual acuity that does not correspond to changes in optical power. Diopter syndrome is manifested by refractive transformations in accordance with changes in the anterior-posterior axis of the eye due to retinal edema. Dry eye syndrome can be manifested by noticeable refractive instability and errors in determining keratometric parameters.High-quality performance of autorefkeratometry, taking into account the nuances, and an in-depth analysis of the data obtained are necessary for making a diagnosis and assessing the dynamics of treatment of ocular pathology.

Statistical Analysis of Atmospheric Delay Gradient and Rainfall Prediction in a Tropical Region

In recent years, precipitable water vapor has emerged as a key atmospheric parameter in weather prediction research. However, relying on only one parameter does not always accurately predict rainfall, as other atmospheric parameters also contribute to initiating rain events. In our previous study, we explored a methodology for rainfall forecasting based on the atmospheric delay gradient at an individual station in the tropical region. Commonly referred to as the atmospheric gradient, it accounts for the delay in GNSS signals due to changes in horizontal refractivity while propagating through the troposphere to the ground station. This paper discusses the spatial and temporal correlation of the gradient with precipitation occurring over a region. We have investigated different features, such as gradient magnitude, gradient convergence, and the flux of the atmospheric gradient, to propose potential nowcasting criteria for precipitation in the tropical climatic zone. The atmospheric gradient in the surrounding region orients toward the area of precipitation as the rain event approaches. This gradient gradually alters its orientation and converges toward the region of rainfall at the time of precipitation, introducing the concept of gradient convergence. This phenomenon results in an inward gradient flux at the time of the downpour, which presents a potential parameter for rainfall prediction over an area. We also proposed investigating area sizes of 4° × 4° or 8° × 8°, depending on the gradient feature, to establish a forecasting methodology for rainfall. The weather front in the tropical region begins to initiate 12 h before the actual time of occurrence and advances toward the area where it will have an impact from a more distant location. This article presents a detailed investigation of various features of the atmospheric gradient and its potential to nowcast rainfall for a region, as well as proposes the lead time for long-term weather predictions. Furthermore, a deep neural network has been employed to predict rainfall events for the next 6 h over an area in the tropical region.

Comparison of different concentrations atropine in controlling children and adolescent myopia: an umbrella review of systematic reviews and meta-analyses.

To evaluate the myopia control effect of different concentrations atropine in children and adolescent. Meta-analyses and systematic reviews available in the Pubmed, Embase, and Cochrane Library databases from the databases' inception to August 2023 were searched to evaluate the efficacy and tolerability of different concentrations' atropine in controlling myopia progression. Overall effects were performed using random-effects model. AMSTAR 2 tool was used to assess the quality of included studies. Prespecified outcomes were weight mean difference (WMD) with 95% credible interval (95% CI) of annual spherical equivalent refraction (SER) changes and annual axial length (AL) changes. 19 systematic reviews/meta-analyses of different atropine concentrations were included in the analysis. 14 studies reported SER changes, and 17 reported AL changes. In terms of the studies' overall methodological quality level (measured using AMSTAR 2), 1 study was rated high, 7 moderate, 7 low, and 4 critically low. The 0.01% atropine was found to have statistically significance (annual SER change WMD 0.27 [95% CI 0.21 - 0.34] D/year; annual AL change WMD -0.09 [95% CI -0.1 to -0.07]) mm/year), 0.05% atropine was preferred considering efficacy and tolerability (annual SER change WMD 0.54 [95% CI 0.49 - 0.58] D/year; annual AL change WMD -0.21 [95% CI -0.12 to -0.02]) mm/year). Different atropine concentrations alleviated children and adolescent myopia progression. However, higher-quality evidence and further investigation are needed to clarify the dose-response relationship, and practical guidelines must be developed to determine myopia control efficacy.