Utility of retinoscopy to examine peripheral refraction

Purpose: This study explored whether retinoscopy (RET) provides comparable results of relative peripheral refraction (RPR) to open–field autorefractometry (AR) in myopic subjects.Methods: Peripheral refraction was measured in 20 myopic and 20 control adult subjects. Both central and peripheral refraction (20° nasal and temporal eccentricity) were measured using RET and open-field AR. Differences in the median central spherical equivalent (SE), median RPR, and median J45/J180 power vectors between the RET and AR techniques were analyzed. Moreover, Bland – Altman plots were used to assess the agreement between RET and AR methods for RPR measurements in MG. Results: For MG, the median RPR values were positive (hyperopic shift), and no significant differences were observed between the RET and AR techniques with respect to RPR measurement. In addition, we did not observe any significant differences in the RPR values between the nasal and temporal eccentricities for either the RET or AR technique for myopic subjects. There was also a significant correlation and agreement between the RET and AR technique for RPR measurements. With respect to central refraction, the median SE was slightly more positive for the RET than for the AR technique. Inside the CG, we also found significant correlation between the RET and AR technique for RPR measurements, and we observed a myopic shift in peripheral eccentricities. Conclusion: Our results show that retinoscopy may be a useful tool for objective measurements of RPR in myopic subjects and may be used interchangeably with the open-field AR method in everyday clinical practice. (AU)

Effect of exogenous calcitriol on myopia development and axial length in guinea pigs with form deprivation myopia.

The annual increase in myopia prevalence poses a significant economic and health challenge. Our study investigated the effect of calcitriol role in myopia by inducing the condition in guinea pigs through form deprivation for four weeks. Untargeted metabolomics methods were used to analyze the differences in metabolites in the vitreous body, and the expression of vitamin D receptor (VDR) in the retina was detected. Following form deprivation, the guinea pigs received intraperitoneal injections of calcitriol at different concentrations. We assessed myopia progression using diopter measurements and biometric analysis after four weeks. Results indicated that form deprivation led to a pronounced shift towards myopia, characterized by reduced choroidal and scleral thickness, disorganized collagen fibers, and decreased scleral collagen fiber diameter. Notably, a reduction in calcitriol expression in vitreous body, diminished vitamin D and calcitriol levels in the blood, and decreased VDR protein expression in retinal tissues were observed in myopic guinea pigs. Calcitriol administration effectively slowed myopia progression, preserved choroidal and scleral thickness, and prevented the reduction of scleral collagen fiber diameter. Our findings highlight a significant decrease in calcitriol and VDR expressions in myopic guinea pigs and demonstrate that exogenous calcitriol supplementation can halt myopia development, enhancing choroidal and scleral thickness and scleral collagen fiber diameter.

Outcomes of cataract surgery in eyes with axial length > 33 mm.

PURPOSE: To evaluate the visual outcomes and perioperative complications for cataract surgery in eyes with axial length (AL) > 33.0 mm. DESIGN: Prospective clinical cohort study. METHODS: One hundred and twenty-two eyes with moderate high myopia (26.0 mm ≤ AL<28.0 mm, control group), and 118 eyes with extreme high myopia (AL > 33.0 mm, EHM group) were followed up after cataract surgery (one week and one year post-op). Myopic maculopathy grading according to ATN system, best-corrected visual acuity (BCVA), and complications were compared. RESULTS: Postoperatively, BCVA in the EHM group improved significantly at both visits (both P < 0.001), despite being worse than that of the control group (both P < 0.05). The EHM group exhibited greater hyperopic refractive errors (P < 0.001), which were found to be associated with more severe T grade, longer AL, poorer second follow-up BCVA, and smaller anterior capsular opening (ACO) area. A higher incidence of retinal detachment and a more constricted ACO were observed in the EHM group (P = 0.030 and < 0.001, respectively), with the latter being significantly associated with longer AL and the absence of capsular tension ring (both P < 0.05). No difference in BCVA was found between the aphakic and pseudophakic eyes in the EHM group at both visits (both P > 0.05). CONCLUSION: Cataract surgery improves vision of eyes with AL > 33 mm, yet the increased risk of perioperative complications requires attention. Leaving these eyes aphakic might be effective and safe in the long term.

Corrigendum: Establishment of noncycloplegic methods for screening myopia and pre-myopia in preschool children.

[This corrects the article DOI: 10.3389/fmed.2023.1291387.].

Unveiling the gut microbiota and metabolite profiles in guinea pigs with form deprivation myopia through 16S rRNA gene sequencing and untargeted metabolomics.

Aim: The aim of this study was to confirm the presence of the form deprivation myopia (FDM) guinea pig eye-gut axis and investigate the relationship between serum vasoactive intestinal peptide (VIP), lipopolysaccharides (LPS), specific gut microbiota and their metabolites. Method: 20 specific-pathogen-free (SPF) guinea pigs were divided into the FDM and the control(Con) group. Following model induction, serum levels of VIP and LPS were quantified. A combination of 16S ribosomal ribosomal Ribonucleic Acid (rRNA) gene sequencing, non-targeted metabolomics and bioinformatics analysis were employed to identify disparities in gut microbiota and metabolites between the two groups of guinea pigs. Result: Compared to the control group, FDM guinea pigs exhibited a significant trend towards myopia, along with significantly elevated concentrations of LPS and VIP (p < 0.0001). Furthermore, Ruminococcus_albus emerged as the predominant bacterial community enriched in FDM (p < 0.05), and demonstrated positive correlations with 10 metabolites, including l-Glutamic acid, Additionally, Ruminococcus_albus exhibited positive correlations with VIP and LPS levels (p < 0.05). Conclusion: The findings suggest that the Ruminococcus_Albus and glutamate metabolic pathways play a significant role in myopia development, leading to concurrent alterations in serum VIP and LPS levels in FDM guinea pigs. This underscores the potential of specific gut microbiota and their metabolites as pivotal biomarkers involved in the pathogenesis of myopia.

POU6F2, a risk factor for glaucoma, myopia and dyslexia, labels specific populations of retinal ganglion cells.

Pou6f2 is a genetic connection between central corneal thickness (CCT) in the mouse and a risk factor for developing primary open-angle glaucoma. POU6F2 is also a risk factor for several conditions in humans, including glaucoma, myopia, and dyslexia. Recent findings demonstrate that POU6F2-positive retinal ganglion cells (RGCs) comprise a number of RGC subtypes in the mouse, some of which also co-stain for Cdh6 and Hoxd10. These POU6F2-positive RGCs appear to be novel of ON-OFF directionally selective ganglion cells (ooDSGCs) that do not co-stain with CART or SATB2 (typical ooDSGCs markers). These POU6F2-positive cells are sensitive to damage caused by elevated intraocular pressure. In the DBA/2J mouse glaucoma model, heavily-labeled POU6F2 RGCs decrease by 73% at 8 months of age compared to only 22% loss of total RGCs (labeled with RBPMS). Additionally, Pou6f2-/- mice suffer a significant loss of acuity and spatial contrast sensitivity along with an 11.4% loss of total RGCs. In the rhesus macaque retina, POU6F2 labels the large parasol ganglion cells that form the magnocellular (M) pathway. The association of POU6F2 with the M-pathway may reveal in part its role in human glaucoma, myopia, and dyslexia.

Ten-year observation of corneal densitometry and associated factors following small incision lenticule extraction.

AIM: To investigate the long-term changes of corneal densitometry (CD) and its contributing elements after small incision lenticule extraction (SMILE). METHODS: Totally 31 eyes of 31 patients with mean spherical equivalent of -6.46±1.50 D and mean age 28.23±7.38y were enrolled. Full-scale examinations were conducted on all patients preoperatively and during follow-up. Visual acuity, manifest refraction, axial length, corneal thickness, corneal higher-order aberrations, and CD were evaluated. RESULTS: All surgeries were completed successfully without complications or adverse events. Ten-year safety index was 1.17±0.20 and efficacy 1.04±0.28. CD value of 0-6 mm zones in central layer was statistically significantly lower 10y postoperatively, compared with preoperative values (0-2 mmΔ=-1.62, 2-6 mmΔ=-1.24, P<0.01). There were no correlations between CD values and factors evaluated. CONCLUSION: SMILE is a safe and efficient procedure for myopia on a long-term basis. CD values get lower 10y postoperatively, whose mechanism is to be further discussed.

Changes in posterior corneal elevation after small incision lenticule extraction for different myopic diopters.

AIM: To study the changes and effect factors of posterior corneal surface after small incision lenticule extraction (SMILE) with different myopic diopters. METHODS: Ninety eyes of 90 patients who underwent SMILE were included in this retrospective study. Patients were allocated into three groups based on the preoperative spherical equivalent (SE): low myopia (SE≥-3.00 D), moderate myopia (-3.00 D>SE>-6.00 D) and high myopia (SE≤-6.00 D). Posterior corneal surfaces were measured by a Scheimpflug camera preoperatively and different postoperative times (1wk, 1, 3, 6mo, and 1y). Posterior mean elevation (PME) at 25 predetermined points of 3 concentric circles (2-, 4-, and 6-mm diameter) above the best fit sphere was analyzed. RESULTS: All surgeries were completed uneventfully and no ectasia was found through the observation. The difference of myopia group was significant at the 2-mm ring at 1 and 3mo postoperatively (1mo: P=0.017; 3mo: P=0.018). The effect of time on ΔPME was statistically significant (2-mm ring: P=0.001; 4-mm ring: P<0.001; 6-mm ring: P<0.001). The effect of different corneal locations on ΔPME was significant except 1wk postoperatively (1mo: P=0.000; 3mo: P=0.000; 6mo: P=0.001; 1y: P=0.001). Posterior corneal stability was linearly correlated with SE, central corneal thickness, ablation depth, residual bed thickness, percent ablation depth and percent stromal bed thickness. CONCLUSION: The posterior corneal surface changes dynamically after SMILE. No protrusion is observed on the posterior corneal surface in patients with different degrees of myopia within one year after surgery. SMILE has good stability, accuracy, safety and predictability.

Effectivity and safety of trifocal intraocular lenses and capsular tension rings implantation for cataract patients with axial high myopia.

AIM: To assess effectivity and safety of trifocal intraocular lenses (IOLs) and capsular tension rings in treating cataract patients with axial high myopia. METHODS: A prospective nonrandomized controlled clinical trial was conducted. Totally 98 eyes (74 patients) who underwent femtosecond laser-assisted cataract surgery (FLACS) with trifocal IOLs were enrolled in the study and followed up for 2y after surgery: 46 eyes (33 patients) with capsular tension ring implantation in the long axial lengths (AL) group (260.05). The dysfunctional lens index and total modulation transfer function (MTF) average height were similar between the two groups. The postoperative internal coma aberrations in the axial high myopia eyes were significantly higher than that in the normal AL group (P<0.05). The total satisfaction score in the long AL group (91.32±2.76) was slightly higher than that in the normal AL group (90.36±3.47), but there was no difference (P=0.136). A statistically negative correlation was found between corrected distance visual acuity (CDVA) and dysfunctional lens index (r=-0.382, P=0.009), and between CDVA and the total MTF average height (r=-0.374, P=0.01). But there was no significant correlation between CDVA and total satisfaction score (r=0.059, P=0.696). Postoperative complications mainly presented as posterior capsular opacity (PCO), retinal detachment and cystoid macular edema. There was no difference in the incidence of fundus disease (6.5% vs 3.8%, P=0.663) or PCO (17.4% vs 7.7%, P=0.217) between the two groups at two years. CONCLUSION: The utilization of trifocal IOL and capsular tension ring implantation is beneficial for cataract patients with axial high myopia undergoing FLACS. This approach not only ensures excellent subjective feelings and objective visual quality, but also does not increase the incidence of postoperative complications.

Refraction and ocular biometric parameters in 3-to 6-year-old preschool children : a large-scale population-based study in Chengdu, China.

PURPOSE: To understand the ocular biometric parameters characteristics and refractive errors in 3-to 6-year-old preschool children in Chengdu, China, and to investigate the prevalence of refractive errors. METHOD: A school-based cross-sectional study was conducted in Chengdu from 2020 to2022 with a total of 666 kindergartens. All children were measured by non-cycloplegic autorefraction and uncorrected visual acuity (UCVA) and ocular biometric parameters. Finally, univariate linear regression models were used to analyze the relationship between ocular biometric parameters and refraction. RESULTS: A total of 108,578 preschool children aged 3-6 underwent examinations, revealing a myopia prevalence of 6.1%. The mean axial length (AL), keratometry (K), corneal radius (CR), axial length/corneal radius (AL/CR) Ratio, central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), and vitreous chamber depth (VCD) were 22.35 ± 0.69 mm, 43.35 ± 1.58 D, 7.80 ± 0.28 mm, 2.87 ± 0.08, 533.31 ± 32.51 µm, 2.70 ± 0.28 mm, 3.91 ± 0.27 mm, and 15.20 ± 0.68 mm, respectively. With increasing age, AL, CR, AL/CR ratio, CCT, ACD, LT, and VCD also increased. Regardless of age, males consistently exhibited longer AL, flatter corneal curvature, shallower ACD, thicker CCT, thinner LT, and longer VCD compared to females. AL, K, CR, LT, and VCD all showed significant linear relationships with SE (all P < 0.001) in univariate linear regression analysis after adjusting for gender and age. CONCLUSION: The prevalence of myopia among preschool children aged 3-6 in Chengdu is relatively low. Ocular biometric parameters affecting refractive errors include AL, K, CR, LT, and VCD. The preschool period serves as a critical phase for myopia prevention and control.

Multimodal imaging of optic nerve head abnormalities in high myopia.

Highly myopic optic nerve head (ONH) abnormalities encompass a series of complications resulting from the stretching of papillary and peripapillary structures during significant axial elongation. The morphological changes in the ONH typically initiate with disk tilting or rotation, progressing to PHOMS and PPA. Tissue defects in each layer manifest as focal lamina cribrosa defects (FLDs), peripapillary intrachoroidal cavitations (PICCs), and acquired pits of the optic nerve (APON). Anterior vitreous/vascular traction and posterior scleral protrusion may lead to prelaminar schisis as well as paravascular cysts and holes, which can potentially develop into retinoschisis. Traditional color fundus photography (CFP) is often insufficient for visualizing most of these lesions, yet their description and quantification benefit significantly from the advancements in optical coherence tomography (OCT) and OCT angiography (OCTA), complemented by fundus autofluorescence (FAF), indocyanine green angiography (ICGA), and three-dimensional imaging. The effective diagnosis and classification of ONH abnormalities heavily rely on a comprehensive understanding of their multimodal imaging features, as outlined in this review. These findings provide valuable insights into optic neuropathy in high myopia, establishing a solid foundation for future endeavors in disease monitoring and treatment guidance.

Effect of 0.01% atropine combined with orthokeratology lens on axial elongation: a 2-year randomized, double-masked, placebo-controlled, cross-over trial.

Purpose: To evaluate the effect of 0.01% atropine combined with orthokeratology (OK) lens on axial elongation in schoolchildren with myopia. Methods: Sixty children aged 8-12 years with spherical equivalent refraction (SER) from -1.00D to -4.00D in both eyes were enrolled in this randomized, double-masked, placebo-controlled, cross-over trial. Children who had been wearing OK lenses for 2 months were randomly assigned into combination group (combination of OK lens and 0.01% atropine) for 1 year followed by control group (combination of OK lens and placebo) for another 1 year or vice versa. This trial was registered in the Chinese Clinical Trial Registry (Number: ChiCTR2000033904, 16/06/2020). The primary outcome was changes in axial length (AL). Data of right eyes were analyzed. Results: There were statistically significant differences in the changes in AL between combination and control groups after generalized estimating equation model adjusting for age and baseline SER (p = 0.001). The mean axial elongation difference between combination and control groups was 0.10 mm in the first year (0.10 ± 0.13 mm vs. 0.20 ±0.15 mm; p = 0.01), and 0.09 mm in the second year (0.22 ± 0.10 mm vs. 0.13 ± 0.14 mm; p = 0.01), respectively. The mean axial elongation difference of two groups in the first year was similar to that in the second year during the cross-over treatment. Conclusion: In central Mainland China in myopic children, the treatment of combination therapy is more effective than single OK lens in controlling axial elongation.

Observation of structural and vascular features of retina and choroid in myopia using ultra-widefield SS-OCTA.

BACKGROUND: To find the relationship between the changes of retinal and choriodal structure/ vascular densities (VD) and the myopia progress. METHODS: 126 eyes of 126 age-matched young participants were divided into three groups: Emmetropia and Low Myopia (EaLM) (33 eyes), Moderate Myopia (MM) (39 eyes), and High Myopia (HM) (54 eyes). Fundus images measuring 12 × 12 mm were captured using ultra-widefield swept-source optical coherence tomography angiography (SS-OCTA). Each image was uniformly divided into nine regions: supra-temporal (ST), temporal (T), infra-temporal (IT), superior (S), central macular area (C), inferior (I), supra-nasal (SN), nasal (N), and infra-nasal (IN). Various structural parameters, including inner retina thickness (IRT), outer retina thickness (ORT), and choroid thickness (CT), were assessed, and the VD of the superficial capillary plexus (SCP), deep capillary plexus (DCP), choriocapillaries (CC), and choroid vessels (ChdV) were quantified. RESULTS: CT in upper fundus exhibited a significant reduction from EaLM to MM. Additionally, ORT (ST, S. SN, C, N, IT, I, IN), CT (ST, S, SN, T, C, N, IT, I, IN) and VDs of SCP (ST, S, C, I, IN), DCP (ST, S, T, C, I) and ChdV (T, N, I, IN) were statistically diminished in EaLM compared to HM. Furthermore, IRT (N), ORT (N, IN), CT (S, SN, T, C, IT, I) and VDs of SCP (I, IN) and DCP (I) exhibited significant decreases as MM progressed towards HM. Intriguingly, there was a notable increase in the VD of CC (ST, S, T, C, N) as myopia progressed from MM to HM. CONCLUSION: Significant changes in retinal and choroid structure and vascular density occur as moderate myopia advances to high myopia. Efforts to curb myopia progression to this stage are essential, as the failure to do so may lead to the development of corresponding retinopathy.

Evaluation of Lag of Accommodation with Full-Field Diffusion Optics Technology™ (DOT) Contrast Management Spectacle Lenses in Emmetropic Children.

Purpose: To evaluate the impact on the lag of accommodation (LOA) in emmetropic children after short-term wear of full-field Diffusion Optics TechnologyTM (DOT) spectacle lenses, designed to modulate retinal contrast to control myopia progression. Patients and Methods: This was a single-visit, prospective, randomized, subject-masked study of emmetropes (ametropes ±1.00D or less in each meridian) with no history of myopia control treatment. Unaided logMAR visual acuity was measured, and ocular dominance was determined using the sighting method. In a randomized order, participants wore plano full-field contrast management (DOT) spectacles (no clear central aperture) or control spectacles (standard single vision spectacle lenses). Each participant was given 5 minutes for adaptation to the respective lenses before open field autorefraction measurements were taken at 6 meters and 40 cm. Ten measurements were taken for each eye. Data were evaluated from the right eye and the dominant eye separately. Results: A total of 30 participants (20 females and 10 males) with a mean age of 10.4 ± 2.8 (7 to 17) years completed the study. There was no significant difference in right eye mean LOA with contrast management spectacles 0.57 ± 0.39D versus control spectacles 0.62 ± 0.34D; Wilcoxon test, p = 0.37. For dominant eyes, LOA values were 0.60 ± 0.40D and 0.68 ± 0.33D with contrast management spectacles and control spectacles, respectively (p = 0.14). Additionally, no significant difference was observed in mean LOA between males and females or between age groups (7-11 years vs 12-17 years) for either right or dominant eyes with contrast management or control spectacles (all p > 0.05). Conclusion: Full-field contrast management spectacle lenses had no significant effect on LOA compared to standard single vision spectacle lenses, indicating no differential impact on accommodative response over the short period of lens wear tested.

Accuracy of Modern Intraocular Lens Formulas in Highly Myopic Eyes Implanted with Plate-Haptic Intraocular Lenses.

PURPOSE: To evaluate the predictive accuracy of modern intraocular lens (IOL) formulas and axial length (AL) adjusted traditional IOL formulas, including Wang-Koch and Cooke-modified AL (CMAL) method, in long eyes with plate-haptic IOLs, and to compare refractive prediction error variances with C-loop IOLs. DESIGN: Retrospective consecutive case series study. METHODS: Data from 391 eyes with Zeiss 509M and 302 eyes with Alcon SN6CWS implants in highly myopic patients, following cataract surgery from January 2019 to November 2023, were collected. One eye per patient was selected. Predictive outcomes of 15 modern formulas (Barrett Universal II (BU II), Cooke K6 (K6), Emmetropia Verifying Optical (EVO) 2.0, Hoffer-QST, Kane, Karmona, Ladas AI, Naeser 2, Olsen, Pearl-DGS, Radial Basis Function (RBF) 3.0, T2, VRF-G, Zhu-Lu, and Z-Calc) and 4 traditional IOL formulas (Haigis, Hoffer Q, Holladay 1, and SRK/T) with AL adjusted methods, were evaluated. The mean prediction error, mean absolute prediction error (MAE), root-mean-square absolute prediction error (RMSAE) and the proportions of eyes with PEs within ±0.25 Diopter (D), ±0.50 D, ±0.75 D and ±1.00 D were analyzed. Top 10 RMSAE-ranked formulas underwent further subgroup analysis based on AL, anterior chamber depth (ACD), and keratometry (K). RESULTS: For the 509M group, RMSAE ranking for the top 10 IOL formulas were the RBF 3.0 (0.432), Zhu-Lu (0.436), Olsen (0.436), EVO 2.0 (0.437), Pearl-DGS (0.447), K6 (0.452), VRF-G (0.454), Naeser 2 (0.464), Haigis-CMAL (0.465) and Karmona (0.477). Karmona and Naeser 2 showed poorer performance in the extremely long AL and steep K subgroups, respectively (p≤0.042). Haigis-CMAL accuracy was significantly lower in shallow ACD and flat K subgroups (p≤0.045). The SN6CWS group showed significantly lower MAE and RMSAE compared to the 509M group for the BU II, EVO 2.0, Hoffer-QST, Kane, Pearl-DGS, and Zhu-Lu formulas (p≤0.024). CONCLUSIONS: In long eyes with plate-haptic IOLs, RBF 3.0 performed best, closely followed by Zhu-Lu, Olsen, and EVO 2.0; Karmona and Naeser 2 are discouraged for extreme AL and steep K conditions, respectively; Haigis-CMAL is not suggested for shallow ACD and flat K cases. Refractive outcomes in eyes implanted with a C-loop design IOL were more accurate than for those implanted with a plate-haptic design, for most tested formulas.

Analysis of risk factors associated with pre-myopia among primary school students in the Mianyang Science City.

Objectives To find out the prevalence rate of pre-myopia among primary school students in the Mianyang Science City Area, analyze its related risk factors, and thus provide a reference for local authorities to formulate policies on the prevention and control of myopia for primary school students. Methods From September to October 2021, Cluster sampling was adopted by our research group to obtain the vision levels of primary school students employing a diopter test in the Science City Area. In addition, questionnaires were distributed to help us find the risk factors associated with pre-myopia. Through the statistical analysis, we identify the main risk factors for pre-myopia and propose appropriate interventions. Results The prevalence rate of pre-myopia among primary school students in the Science City Area was 45.27% (1020/2253), of which 43.82% were boys and 46.92% were girls, with no statistically significant difference in the prevalence rate of myopia between boys and girls (2 =2.171, P=0.141). The results of the linear trend test showed that the prevalence rate of pre-myopia tends to decrease with increasing age (Z=296.521, P=0.000). Logistic regression analysis demonstrated that the main risk factors for pre-myopia were having at least one parent with myopia, spending less than 2 hours a day outdoors, using the eyes continuously for more than 1 hour, looking at electronic screens for more than 2 hours, and having an improper reading and writing posture. Conclusion The Science City Area has a high prevalence rate of pre-myopia among primary school students. It is proposed that students, schools, families, and local authorities work together to increase the time spent outdoors, reduce digital screens and develop scientific use of eye habits.

Peripheral myopic defocus signal affects the efficiency of visual information processing in myopic children.

PURPOSE: Spectacle lenses with peripheral lenslets have shown promise for myopia control by providing peripheral myopic defocus signals. Here, we aimed to investigate the impact of prolonged exposure (>6 months) to peripheral myopic defocus on visual information processing in myopic children. METHODS: The study included 30 myopic children who habitually wore spectacle lenses with highly aspherical lenslets (HAL group) and 34 children who habitually wore single-vision (SV group) spectacles. The quick contrast sensitivity function (qCSF) was used to measure contrast sensitivity (CS) under conditions of no or high noise. Both groups were tested with HAL and SV lenses. The perceptual template model was utilised to fit the contrast sensitivity function (CSF) and determine differences in information processing efficiency through internal additive noise ( N add $$ {N}_{\mathrm{add}} $$ ) and perceptual template gain (ß). RESULTS: The areas under the log CSF in the SV group were significantly higher than for the HAL group in both zero-noise conditions with the SV test lens (p = 0.03) and high-noise conditions with the HAL test lens (p = 0.02). For 2 cycle per degree (cpd) stimuli, ß was significantly higher in the SV group with the HAL test lens than in the HAL group (p = 0.02), while there was a trend towards a significant difference in ß for 6 cpd stimuli (p = 0.07). However, there were no significant differences in N add $$ {N}_{\mathrm{add}} $$ between the two groups, with or without noise interference. CONCLUSION: The reduced CS observed in myopic children wearing HAL lenses for 6 months or more may be due to decreased ß. This suggests that prolonged use of spectacle lenses with peripheral myopic defocus signals may compromise the central visual system's ability to process additional external noise, resulting in decreased efficiency in visual information processing.

Mechanisms of emmetropization and what might go wrong in myopia.

Studies in animal models and humans have shown that refractive state is optimized during postnatal development by a closed-loop negative feedback system that uses retinal image defocus as an error signal, a mechanism called emmetropization. The sensor to detect defocus and its sign resides in the retina itself. The retina and/or the retinal pigment epithelium (RPE) presumably releases biochemical messengers to change choroidal thickness and modulate the growth rates of the underlying sclera. A central question arises: if emmetropization operates as a closed-loop system, why does it not stop myopia development? Recent experiments in young human subjects have shown that (1) the emmetropic retina can perfectly distinguish between real positive defocus and simulated defocus, and trigger transient axial eye shortening or elongation, respectively. (2) Strikingly, the myopic retina has reduced ability to inhibit eye growth when positive defocus is imposed. (3) The bi-directional response of the emmetropic retina is elicited with low spatial frequency information below 8 cyc/deg, which makes it unlikely that optical higher-order aberrations play a role. (4) The retinal mechanism for the detection of the sign of defocus involves a comparison of defocus blur in the blue (S-cone) and red end of the spectrum (L + M-cones) but, again, the myopic retina is not responsive, at least not in short-term experiments. This suggests that it cannot fully trigger the inhibitory arm of the emmetropization feedback loop. As a result, with an open feedback loop, myopia development becomes "open-loop".

Clinical and genetic characteristics and natural history of Finnish families with familial exudative vitreoretinopathy due to pathogenic FZD4 variants.

PURPOSE: To report clinical and genetic characteristics of familial exudative vitreoretinopathy (FEVR) in the Finnish population. METHODS: Detailed clinical and genetic data of 35 individuals with heterozygous pathogenic variants in FZD4 were gathered and analysed. RESULTS: Thirty-two individuals with FZD4 c.313A>G variant and three individuals with FZD4 c.40_49del were included in the study. The clinical phenotype was variable even among family members with the same FZD4 variant. Only 34% (N = 12/35) of variant-positive individuals had been clinically diagnosed with FEVR. The median age of the onset of symptoms was 2.3 years, ranging between 0 to 25 years. Median visual acuity was 0.1 logMAR (0.8 Snellen decimal), ranging between light perception and -0.1 logMAR (1.25 Snellen decimal). Most (N = 33/35, 94%) were classified as not visually impaired. Despite unilateral visual loss present in some, they did not meet the criteria of visual impairment according to the WHO classification. Two study patients (N = 2/35, 6%) had severe visual impairment. The most common FEVR stage in study patient's eyes (N = 28/70 eyes, 40%) was FEVR stage 1, that is, avascular periphery or abnormal vascularisation. Most of FZD4-variant-positive study patient's eyes (N = 31/50 eyes, 62%) were myopic. Two individuals presented with persistent hyperplastic primary vitreous expanding the phenotypic spectrum of FEVR. Shared haplotypes extending approximately 0.9 Mb around the recurrent FZD4 c.313A>G variant were identified. CONCLUSION: Most study patients were unaffected or had mild clinical manifestations by FEVR. Myopia seemed to be overly common in FZD4-variant-positive individuals.

Low-level red-light therapy for myopia control in children: A systematic review and meta-analysis.

INTRODUCTION: Low-Level Red-Light (LLRL) Therapy is a safe and natural way to promote healing and reduce inflammation in the body. When it comes to treating myopia in children, LLRL therapy is recent, and its efficacy and safety still are not clear. METHODS: A systematic review and meta-analysis of the literature for LLRL was conducted in accordance with the PRISMA guidelines on November 5, 2022. Databases, including PUBMED, Cochrane Library, Web of Science, and Embase were queried. A meta-analysis of random effects was conducted. Inclusion criteria included Randomized Controlled Trials (RCTs) or observational studies where LLRL therapy was used in children (3‒15 years old) with myopia. Exclusion criteria were studies with other ocular abnormalities. Efficacy was evaluated through the mean change in Axial Length (AL) and cycloplegic Spherical Equivalent Error (SER), while safety was evaluated by monitoring adverse effects. RESULTS: A total of 5 final studies were included (4 RCTs, and 1 observational), in which 685 total patients were analyzed. The mean age was 9.7 ± 0.66 years, with 48,2% female patients. The number of eyes in the LRLL arm is 714 and, in the control, arm is 656. LLRL showed better results in SER and AL mean change (OR = 0.58; 95% CI 0.33 to 0.83; p < 0.00001, and MD -0.33; 95% CI -0.52 to -0.13; p = 0.001, respectively), in comparison to the control group. There was no significant difference in adverse effects between groups (MD = 5.76; 95% CI 0.66 to 50.14; p = 0.11). CONCLUSION: LLRL therapy is a non-invasive, effective, and safe short-term treatment option; however, long-term evaluation, particularly in comparison to other therapies, requires additional investigation.