Refractive Status Research Articles

Vision impairment in boys recruited to the iREAD study

BackgroundUncorrected refractive error is reported to be the most common cause globally of vision impairment in school age children. However, little is known about the extent of uncorrected refractive error in Israel. The purpose of this study was to investigate the prevalence of vision impairment in schoolchildren recruited for the Israel Refraction, Environment, And Devices (iREAD) Study.MethodsHealthy boys, ages 5–13 years, were recruited to participate in the iREAD Study. Parents first answered a questionnaire to exclude children with a known history of amblyopia, strabismus, or hyperopia. A comprehensive eye exam was then performed. Presenting visual acuity < 6/12 was defined as vision impairment. Myopia and hyperopia were defined as cycloplegic spherical equivalent refraction ≤ − 0.50 D, and ≥ + 0.50 D, respectively, and astigmatism as ≤ − 0.75 D. Amblyopia was defined as best corrected visual acuity ≤ 6/12 in at least one eye in the absence of any ocular pathology. Descriptive statistics were used to calculate the prevalence of each refractive error and amblyopia.ResultsTwo hundred five boys (average age 8.8 ± 1.7 years) presented for a comprehensive eye exam. The prevalence of vision impairment at initial presentation was 22.9% (N = 47), with 16.1% (N = 33) and 6.8% (N = 14) for both eyes and one eye, respectively. Of the children with vision impairment, 36.2% (N = 17) were wearing habitual correction. Of the children with vision impairment, 97.9% (N = 46) had refractive error, with 85.1% (N = 40) being myopic and 12.8% (N = 6) being hyperopic. In addition, 36.2% (N = 17) with vision impairment had astigmatism. Most children with vision impairment (N = 43) achieved good vision with refractive correction. However, amblyopia was observed in 2.0% (N = 4) of the children.ConclusionsA high prevalence of vision impairment was observed, primarily due to uncorrected or undercorrected refractive error. Children with amblyopia and/or hyperopia presented despite a parent questionnaire to exclude children with these conditions. Findings suggest that many parents are unaware of their children’s visual and refractive status, even for children who already have glasses. In conclusion, improvements to the current system in Israel of vision screenings in first grade should be made to help insure children in need receive adequate follow-up throughout their education.

Prevalence of Ishihara Test Failures in a Large Cohort of Military Conscripts.

Color vision deficiency (CVD) is a common vision disorder. It is predominantly caused by inherited photopigment abnormalities in the retina. The absolute number of cases with CVD is expected to increase worldwide with the growing population. Data from male military conscripts for the recruitment period of 2008 to 2017 were retrospectively analyzed. Year of recruitment, conscripts' birth year, visual acuity, refractive status (spherical equivalent), and color vision status (normal Ishihara pseudoisochromatic plates test yes/no) were available. The dataset comprised data on a total of 355 657 male conscripts who had undergone recruitment between the years 2008 to 2017. The mean number of conscripts per year was 35 566 (MD = 35 440, SD = 1 249), reaching a minimum count of 33 998 conscripts in 2017 and a maximum of 37 594 in 2011. The mean age at recruitment was 19.7 years (MD = 19.0 y, SD = 1.1 y). Among the conscripts, 337 422 (94.9%) successfully passed the Ishihara test, while 18 235 (5.1%) were found to have CVD. The overall prevalence of CVD in our male cohort was 5.1%. This figure is slightly lower than that reported for a European Caucasian population.

Stability of small incision lenticule extraction over laser in situ keratomileusis at an altitude of 3874 m

The purpose of this study was to evaluate the stability of small-incision lenticule extraction (SMILE) and laser in situ keratomileusis (LASIK) when ascending from near sea level to an altitude of 3874 m. The visual acuity (VA), intraocular pressure (IOP), spherical equivalent refraction (SER) and biometric parameters of 20 normal subjects (40 eyes, controls) and 36 subjects who underwent corneal refractive surgery (35 eyes with SMILE and 36 eyes with LASIK) were examined in Chongqing (C, 500 m above sea level) and 7–10 days after a collective travel to Shigatse (S, 3874 m above sea level). SER and corneal thickness (CT) were choosed as main indicators of the stability of corneal refractive surgery at high altitude. The IOP decreased and CT increased from C to S, while VA and SER did not significantly change in the control subjects. The VA and IOP of both the SMILE and LASIK subjects did not significantly change at an altitude of 3874 m. At high altitudes, no significant difference in the SER was found among the SMILE subjects, while a significant myopic shift was found among the LASIK subjects. With an increase in the altitude of 3874 m in S, an obvious increase in CT was observed in subjects who underwent corneal refraction surgery. The increase in CT in the SMILE group was significantly less than the increase in CT in the LASIK group. In addition, the biometric parameters of the SMILE and LASIK subjects showed the same minor changes as those of the control subjects when exposed to high altitude. The VA, IOP and biometric parameters of the subjects who underwent SMILE and LASIK remained stable at an altitude of 3874 m. SMILE shows better stability than LASIK in the refractive state and CT when exposed to high altitude.Trial registration: This study was approved by the Ethics Committee of The Second Affiliated Hospital of Army Medical University (ID: 2022-No.084-1) and adhered to the principles of the Declaration of Helsinki. The study was registered at http://www.chictr.org.cn (Study NO. ChiCTR2200059833) on 12/5/2022.

Refractive error maps: A predictive tool for refractive error progression.

To investigate the influence of axial length on different ocular parameters and create a predictive tool for refractive error progression. Two eye models were used to simulate refractive errors, namely the Liou-Brennan and the Goncharov-Dainty. Both models were simulated using Zemax OpticStudio. Simulations were made by varying axial length and central corneal radii of curvature, with values ranging from 21.5 to 28.5 mm and 7.0 to 8.5 mm, respectively. Additionally, simulations of different lens parameters were included. Refractive error maps were produced for different ethnicities and a comparison with experimental results was undertaken. These showed the relationships between axial length and crystalline lens thickness, refractive index and curvatures of the cornea and lens. The concept of refractive error maps may provide more insight into the refractive state of individuals and groups with provision for a comparative analysis. With further experimental data added, such refractive error maps could be used as a predictive tool.

Corneal Biomechanical Characteristics and Correlation Analysis in Children With Different Refractive States.

Purpose: To investigate the correlation between corneal biomechanical characteristics and refractive status in adolescents aged 5-13 years. Methods: A cross-sectional study involved 339 children aged 5-13 with a spherical equivalent (SE) range from -6.00 to +2.00 diopters. Axial length (AL) was measured by IOL Master, corneal biomechanical parameters by Corvis ST, and anterior segment parameters by Pentacam. According to SE of right eye, the subjects were divided into moderate myopia, mild myopia, and emmetropia group. The correlation between AL and SE and corneal biomechanical parameters was analyzed. The corneal biomechanical parameters of the three groups were also compared. Results: The A2V value in the moderate myopia group was significantly lower than that in both the mild group and emmetropia group (p < 0.001). PD in the moderate group was higher than that in the mild group (p < 0.05), while PD in mild myopia was higher than that in emmetropia (p < 0.05). The SSI in the emmetropia group was significantly higher than that in the other two groups (all p < 0.001), and the SSI in the mild group was higher than that in the moderate group (p < 0.01). The A2V value in the 11-13 years old group was lower than that in the 5-7 years old group (p < 0.001) and 8-10 years old group (p < 0.01). PD in the 11-13 years old group was significantly higher than that in the 8-10 years old group (p < 0.001), and PD in the 8-10 years old group was significantly higher than that in the 5-7 years old group (p < 0.01). The SSI in the 5-7 years old group was significantly higher than that in the 8-10 years old group (p < 0.001), and the SSI in the 8-10 years old group was significantly higher than that in the 11-13 years old group (p < 0.05). AL was positively correlated with PD and negatively correlated with SSI and A2V. SE was positively correlated with A2V and SSI and negatively correlated with PD. Conclusions: Corneal stiffness seems to decrease with the increase of SE. The changes of SSI, PD, and A2V were statistically significant and can be predictors of myopia progression in adolescents aged 5-13 years.

Femtosecond laser assisted phacoemulsification plus IOL implant: Toric IOL vs astigmatism keratotomy

Aims/Purpose: This study aimed at comparing the clinical outcomes of femtosecond laser‐assisted cataract surgery (FSACS) performing astigmatic keratotomy (AK) and toric intraocular lens (IOLt) implantation for astigmatism correction.Methods: Based on autorefractor and corneal topography, all patients underwent pre‐operative and postoperative examinations including comparatively assessing refractive astigmatism, best corrected visual acuity and corneal high order aberrations.Results: This retrospective case series comprised a total of 20 eyes (IOLt: AK = 10: 10) of 16 patients (mean age: 62.70 ± 1.89 years). Refraction status was 1.98 ± 0.22 in IOLt (0.75~3.00 D) vs 1.95 ± 0.23 in AK (0.55~3.08 D). The follow‐up periods 9.63 ± 1.15 months after surgery.Total corneal astigmatism (CAtot) were 1.73 ± 0.20 D in IOLt/2.28 ± 0.23 D in AK preoperatively and significantly (p &lt; 0.01/p &lt; 0.001) reduced to 0.80 ± 0.17 D in IOLt/1.13 ± 0.07 D in AK. The pre‐operative and postoperative reduction in astigmatism between IOLt (0.93 ± 0.32 D) and AK (1.15 ± 0.21) was not significantly (p = 0.56) different. However, anterior corneal astigmatism (CAant) were 1.99 ± 0.21 D in IOLt/1.95 ± 0.23 in AK preoperatively and not significantly/significantly (p = 0.36/p &lt; 0.05) reduced to 1.73 ± 0.18 D in IOLt/1.10 ± 0.18 D in AK. Regarding CAant, the pre‐operative and postoperative reduction in astigmatism between IOLt (0.36 ± 0.25 D) and AK (0.69 ± 0.21 D) was not significantly (p = 0.3) different.Pre‐FSACS IOLt total corneal HOAs (0.47 ± 0.15) decreased, but not significantly, after FSACS IOLt (0.41 ± 0.11; p = 0.76). However, pre‐FSACS AK total corneal HOAs (0.19 ± 0.02) significantly increased after FSACS AK (0.29 ± 0.03; p &lt; 0.01). Furthermore, the pre‐operative and postoperative changes in total corneal HOAs between IOLt (‐0.06 ± 0.04) and AK (0.10 ± 0.02 D) were significantly (p &lt; 0.01) different.Best corrected visual acuity (Snellen E) was preoperatively 0.42 ± 0.02 in IOLt/0.38 ± 0.02 in AK and significantly (p &lt; 0.001) increased to 0.82 ± 0.06 in IOLt/0.74 ± 0.07 in AK postoperatively. The preoperative and postoperative BCVA alteration was not significant between two groups (IOLt vs AK: 0.40 ± 0.04 vs 0.36 ± 0.07; p = 0.64).Conclusions: IOLt implantation efficient and harmless for correcting preoperative astigmatism in FSACS in a short period.

Reply Re: “Modified Conjoint Fascial Sheath and Levator Muscle Complex Suspension for the Correction of Simple Severe Congenital Ptosis in Pediatrics and the Effect on Refractive Status”

Reply Re: “Modified Conjoint Fascial Sheath and Levator Muscle Complex Suspension for the Correction of Simple Severe Congenital Ptosis in Pediatrics and the Effect on Refractive Status”

Actual lens position of three intraocular lenses in highly myopic eyes: An ultrasound biomicroscopy‐based study

Aims/Purpose: To evaluate the actual lens positions (ALPs) of three intraocular lenses (IOLs) in highly myopic eyes and to identify relevant factors using ultrasound biomicroscopy (UBM).Methods: Ninety‐three highly myopic eyes (93 patients) that underwent uneventful cataract surgery were included: 36 eyes were implanted with Zeiss 409MP IOLs, 27 with Rayner 920H IOLs, and 30 with HumanOptics MCX11 IOLs. The prediction error (PE), ALP determined by UBM, and the factors associated with ALP at 3 months after surgery were evaluated.Results: The eyes in the MCX11 IOL group had a more hyperopic PE (0.67 ± 0.45 diopters [D]) and greater ALP (4.86 ± 0.39 mm) than those in the 409MP and 920H IOL groups at 3 months after surgery (PE: −0.25 ± 0.54 and −0.16 ± 0.65 D, respectively; ALP: 4.34 ± 0.26 and 4.14 ± 0.32 mm, respectively). The MCX11 IOLs showed more backward bending deformation after surgery than 409MP and 920H IOLs. The radius of curvature of the IOL was negatively correlated with ALP (r = −0.532, p = 0.002) in the MCX11 IOL group, but not in the other two groups. Multivariate analysis showed that MCX11 IOLs were more prone to bending in highly myopic eyes with a smaller anterior capsular opening (β = 0.236, p = 0.023) and lower implanted power (β = 0.542, p = 0.001).Conclusions: In highly myopic eyes, IOLs with good capsular support show less backward bending, which result in a more stable lens position and refractive status postoperatively. Severe capsular contraction and low implanted power are risk factors for bending of certain IOLs.

Actual lens position of three intraocular lenses in highly myopic eyes: an ultrasound biomicroscopy‐based study

Aims/Purpose: To evaluate the actual lens positions (ALPs) of three intraocular lenses (IOLs) in highly myopic eyes and to identify relevant factors using ultrasound biomicroscopy (UBM).Methods: Ninety‐three highly myopic eyes (93 patients) that underwent uneventful cataract surgery were included: 36 eyes were implanted with Zeiss 409MP IOLs, 27 with Rayner 920H IOLs, and 30 with HumanOptics MCX11 IOLs. The prediction error (PE), ALP determined by UBM, and the factors associated with ALP at 3 months after surgery were evaluated.Results: The eyes in the MCX11 IOL group had a more hyperopic PE (0.67 ± 0.45 diopters [D]) and greater ALP (4.86 ± 0.39 mm) than those in the 409MP and 920H IOL groups at 3 months after surgery (PE: −0.25 ± 0.54 and −0.16 ± 0.65 D, respectively; ALP: 4.34 ± 0.26 and 4.14 ± 0.32 mm, respectively). The MCX11 IOLs showed more backward bending deformation after surgery than 409MP and 920H IOLs. The radius of curvature of the IOL was negatively correlated with ALP (r=−0.532, p = 0.002) in the MCX11 IOL group, but not in the other two groups. Multivariate analysis showed that MCX11 IOLs were more prone to bending in highly myopic eyes with a smaller anterior capsular opening (β=0.236, p = 0.023) and lower implanted power (β=0.542, p = 0.001).Conclusions: In highly myopic eyes, IOLs with good capsular support show less backward bending, which result in a more stable lens position and refractive status postoperatively. Severe capsular contraction and low implanted power are risk factors for bending of certain IOLs.

Photoreceptor layer elevation due to subretinal fluid: Impact on visual acuity measurements and simulation from biometrics.

Visual acuity (VA) is a primary outcome measure that defines the success of clinical interventions for retinal diseases such as age-related macular degeneration (AMD) or diabetic macular oedema (DME). These conditions can lead to the presence of subretinal fluid, causing substantial photoreceptor layer elevation. Hyperopic defocus then occurs, affecting the VA measurements. In this study, we simulated the induced hyperopic shift for real-world values of photoreceptor layer elevation and measured the effect on VA measurements. To simulate the hyperopic shift, we used a four-surface eye model. To measure the effect of defocus on VA, normally sighted adults (N = 44, mean [SD] age = 32 [13.0] year, range: 21-71 year) performed four test conditions, that is, defocus of 0.00, +0.75, +1.50 and +2.25 D. For each subject, mean VA and SD obtained from a cumulative normal fit to the VA data provided the coefficient of variation (CV) and 95% confidence interval (CI). Refractive error induced by photoreceptor layer elevation was maximum for hyperopic error conditions, followed by emmetropic and myopic refractive error conditions. The 76% threshold VA worsened with increasing defocus conditions. The 95% CI was significantly larger for +0.75, +1.50 and +2.25 D defocus compared to no defocus (p = 0.04, 0.02 and 0.01, respectively). The CI for the +2.25 D defocus condition was larger (3-10 letters) compared with no defocus (3-6 letters). Photoreceptor layer elevation causes a hyperopic shift sufficient for clinically meaningful changes: worse VA and more variable measurements.

Intraoperative aberrometry-assisted refractive optimization of SFIOL.

Scleral-fixated intraocular lens (SFIOL) is a widely used technique for IOL implantation in patients where capsular support is insufficient. Most surgeons have shifted away from sutured to sutureless SFIOL techniques where haptics of a multifocal IOL are inserted in scleral tunnels/flaps. Large-scale publications have shown wide variation in the refractive status of eyes post-SFIOL even in the best of the hands. This is because even slight variations in the site of scleral flap/tunnel formation and tension on haptics due to the variable length of haptics placed in scleral flaps/tunnels can alter the effective lens position and induce significant residual refractive error, especially cylindrical astigmatism due to IOL tilt. Our technique aims to reduce residual refractive error after SFIOL implantation. This is achieved by using intraoperative aberrometry and adjusting haptics accordingly to achieve minimal refractive error intraoperatively.

Ocular biometric parameters in Chinese preschool children and physiological axial length growth prediction using machine learning algorithms: a retrospective cross-sectional study

ObjectivesTo examine the ocular biometric parameters and predict the annual growth rate of the physiological axial length (AL) in Chinese preschool children aged 4–6 years old.MethodsThis retrospective cross-sectional study included...

Refraction difference value variations in children and adolescents with different refractive errors.

To evaluate the refraction difference value (RDV) variations in children and adolescents with different refractive errors and analyze its correlation with refractive development. Participants aged 4-16y with different refractive statuses (hyperopia, emmetropia, myopia) underwent comprehensive eye examinations, including spherical equivalent (SE) refraction, axial length (AL), total RDV (TRDV), and RDVs at various eccentricities (0°-15°, 15°-30°, 30°-45°) and quadrants (inferior, superior, nasal, temporal). Statistical analysis involved one-way ANOVA for group comparisons and Pearson correlation for examining relationships between SE/AL and RDVs. Paired t-tests compared quadrant-specific RDVs within groups. Significant difference was found in TRDV (P<0.001), RDV15°-30° (P=0.033), RDV30°-45° (P<0.001), RDV-inferior (RDV-I, P<0.001) and RDV-temporal (RDV-T, P<0.001) among hyperopia, emmetropia and myopia group. Pearson correlation analysis revealed a negative correlation of SE with TRDV (P=0.001), RDV30°-45° (P=0.004), RDV-I (P=0.047), and RDV-T (P<0.001). The differences between RDV-superior (RDV-S) and RDV-I were statistically significant in all groups (P<0.001 for all) and between RDV-T and RDV-nasal (RDV-N) were statistically significant in hyperopia group (P<0.001). Within the pre-myopic group, the analysis revealed a negative correlation of SE with RDV-I (P=0.009). Pearson correlation analysis revealed a positive correlation of AL with TRDV (P=0.036), RDV15°-30° (P=0.004), RDV30°-45° (P<0.001), RDV-S (P=0.003), RDV-I (P<0.001), RDV-T (P<0.001), RDV-N (P=0.022), while revealed a negative correlation of AL with RDV0-15° (P=0.018). Our study indicates TRDV, RDV30°-45°, RDV-I, RDV-T may relate to refractive development, and a negative correlation between SE and RDV-I in pre-myopic children.

Prevalence of refractive errors in school-aged and preadolescent children in Colombia.

To describe the distribution of refractive errors by age and sex among schoolchildren in Soacha, Colombia. This was an observational cross-sectional study conducted in five urban public schools in the municipality of Soacha. A total of 1161 school-aged and pre-adolescent children, aged 5-12y were examined during the school year 2021-2022. Examinations included visual acuity and static refraction. Spherical equivalent (SE) was analysed as follows: myopia SE≤-0.50 D and uncorrected visual acuity of 20/25 or worse; high myopia SE≤-6.00 D; hyperopia SE≥+1.00 D (≥7y) or SE≥+2.00 D (5-6y); significant hyperopia SE≥+3.00 D. Astigmatism was defined as a cylinder in at least one eye ≥1.00 D (≥7y) or ≥1.75 D (5-6y). If at least one eye was ametropic, children were classified according to the refractive error found. Of the 1139 schoolchildren included, 50.6% were male, 58.8% were aged between 5 and 9y, and 12.1% were already using optical correction. The most common refractive error was astigmatism (31.1%), followed by myopia (20.8%) and hyperopia (13.1%). There was no significant relationship between refractive error and sex. There was a significant increase in astigmatism (P<0.001) and myopia (P<0.0001) with age. Astigmatism is the most common refractive error in children in an urban area of Colombia. Emmetropia decreased and myopia increased with age.

Kirigami Design Smart Contact Lens for Highly Sensitive Eyelid Pressure Measurement.

Eyelid pressure is a crucial biomechanical parameter for ocular health and refractive status, yet measuring it poses challenges related to flexibility, sensitivity, and regional specificity. This study introduces a novel smart contact lens that incorporates kirigami designs and an iontronic capacitive sensing array to enhance flexibility and conformability. The unique structural composition of this device allows for precise and simultaneous monitoring of eyelid pressure in multiple regions with a high sensitivity and seamlessly fit across corneal curvatures. The efficacy of the sensor has been thoroughly confirmed through comprehensive evaluations in rabbits and porcine eyes, demonstrating improved conformity and sensitivity compared to conventional single-point sensors. Assessments have been conducted in various conditions, including under anesthesia and in awake states, as well as the deliberate alteration of intraocular pressure fluctuations, all affirming the exceptional accuracy in detecting eyelid pressure. We envision that the smart contact lens has the potential to revolutionize diagnosis and management of eyelid-related ocular diseases.

Types of refractive errors in a sample of Iraqi children with Intermittent exotropia

Background One of the most common strabismus types in children is intermittent exotropia, which predominantly occurs in children between the ages of 2 to 4 years. It may affect visual development and often coexists with refractive errors. Unlike esotropia, which usually links to hyperopia, intermittent exotropia might have a different relationship with refractive errors and thus lead to myopia. Methods In this cross-sectional retrospective study from August 2021 to December 2023, 179 patients diagnosed with intermittent exotropia were recruited via an outpatient clinic of Najah Al-Quraishi, Baghdad, Iraq. The refractive errors were compared by autorefractometry and retinoscopy after cycloplegic dilation. Data analysis was constructed under the use of IBM SPSS V.26 for the determination of emmetropia, myopia, and hyperopia prevalence. Results Among the 179 patients, emmetropia was the most commonly observed refractive status, present in 68 patients (38%). Low hyperopia and low myopia were also common, with 64 and 40, respectively. A limited number of patients had moderate/high myopia and moderate/high hyperopia; in detail, the prevalence was following: 5% of patients had moderate myopia, while 0.5% of patients suffered from high myopia; symmetrically, 5% were moderate to high hyperopia. From the data collected, a trend emerged for a low refractive error and symmetric refractive error in both eyes. Conclusion Contrasted to prior conventional wisdom about refractive error in strabismus, it established the greater incidence of emmetropia in patients with intermittent exotropia. The findings call for specific management strategies to be applied in this population.

Effects of Stage Lighting on Visual Comfort at Summer Festivals: A Study in Portugal.

Background: The primary objective of this study was to assess the visual comfort and health impacts of stage lighting on attendees at summer festivals. Specifically, the study aimed to evaluate the effects of different types of lighting, including natural, artificial, and stage lighting, on symptoms such as glare, eye strain, tearing, and temporary vision loss. Methods: A survey was conducted among attendees of various summer festivals in Portugal. Participants were asked about their perceptions of lighting conditions and the related visual symptoms they experienced. The survey addressed sensitivity to different types of lighting, the impact of smoke on eye discomfort, and potential strategies for improving visual comfort. Data analysis was performed using IBM SPSS® v.27 to explore trends and correlations. Results: The findings indicated that cooler stage lighting was associated with a higher incidence of glare, with male participants reporting greater discomfort than females. However, there were no significant differences between gender, age, or refractive status when examining the effects of smoke on symptoms like dry eyes and tearing. Notably, participants aged 19-25 experienced more frequent tearing under stage lighting. Key recommendations included the use of high-quality LED lighting, supported by 44.81% of respondents, and the provision of low-light areas for visual rest, which 37.66% of participants deemed essential. Additional suggestions included minimizing intermittent lights and increasing the awareness of vision protection to improve visual comfort. Conclusions: This study highlights the importance of optimizing stage lighting to enhance visual comfort at summer festivals. Festival organizers are encouraged to implement high-quality LED lighting and directional lighting technologies, as well as to create low-light zones for visual rest. Reducing the use of flashing or intermittent lights and providing eye protection information to attendees are also crucial steps to improve the overall visual experience and safeguard eye health at large-scale events.

Relationship between genotype, phenotype, and refractive status in patients of inherited retinal degeneration.

To elucidate the relationship between inherited retinal disease, visual acuity and refractive error development in Asian patients. Five hundred phakic eyes with refractive data were analysed in this retrospective cohort. Diseases were categorized by clinical phenotypes, and the prevalent genotypes identified in the Taiwan Inherited Retinal Degeneration Project were analysed. Consecutive surveys in Taiwan have provided the rates of myopia in the general population. No differences were observed among the disease phenotypes with respect to myopia (P = 0.098) and high myopia rates (P = 0.037). The comparison of refractive error between retinitis pigmentosa and diseases mainly affecting the central retina showed no difference, and the refraction analyses in diseases of different onset ages yielded no significance. Moreover, there was no difference in the myopia rate between the diseases and general population. Among the genotypes, a higher spherical equivalent was seen in RPGR and PROM1-related patients and emmetropic trends were observed in patients with CRB1 and PRPF31 mutations. Furthermore, significantly poorer visual acuity was found in ABCA4, CRB1 and PROM1-related patients, and more preserved visual acuity was seen in patients with EYS, USH2A, and RDH12 mutations. No significant differences were observed in visual acuity, refractive state and myopia rate between patients with inherited retinal disease and the general population, and different subtypes of inherited retinal disease shared similar refractive state, except for higher cylindrical dioptres found in patients with Leber's congenital amaurosis. The heterogeneity of disease-causing genes in Asian patients may lead to variable refractive state.

Effect of school entrance age on myopia among primary schoolchildren using mixed-effect model: The Shantou Myopia Study (SMS).

To investigate the association between children's school entrance age and refractive status and prevalence of myopia in southern China. Population-based Cross-sectional study was conducted from September 2020 to June 2021 in Shantou, southern China, enrolling primary schoolchildren in the city. The school entrance age was calculated as the months from the birth date to the entrance date, divided by 12. Non-cycloplegic refraction and uncorrected visual acuity test were conducted. Myopia was defined as spherical equivalent refraction (SER) < -0.50D with an uncorrected distant visual acuity < Snellen 20/20. We explored the association between the SER and the school entrance age, with the clustering effect within schools adjusted by the linear mixed-model. We enrolled 410,080 primary schoolchildren, with a mean age of 9.8 ± 1.6 years. The overall prevalence of myopia was 42.04 %. The mean SER of myopic children was - 2.15 ± 1.70 D. The mixed-effects model revealed a significant correlation between the school entrance age and the SER and the prevalence of myopia. One year later for school entrance age would independently result in a less myopic SER of 0.352 D, and significantly decrease the prevalence of myopia. Children born before September 1st had significantly more myopic SER than those born after September 1st. Early school entrance, rather than age or prolonged exposure to schooling, was an independent risk factor for myopia. It is important to put forward some scientific and effective measures, preventing children from early exposure to task-heavy school life and near work.

The potential role of fixation eye movements in the development of myopia

Myopia, a globally public health problem, referring to an abnormal refractive state in which the focus falls in front of retina due to extended axial length, is always regarded as an excessive emmetropia process and extreme ocular growth. Fixation eye movements (FEMs), small eye movements occurring incessantly during our gazes to maintain continuous attention and keep clear vision, have been considered to participate in the emmetropization process, yet their role in relation to myopia development has not been clearly demonstrated. It is possible that abnormal fixation eye movements could contribute to the onset and progression of myopia. Although the role of fixation eye movements (FEMs) in the setting of myopia has not yet been investigated, previous researches have demonstrated that patients with myopic refractive error performed significantly abnormal FEMs characteristics, suggesting the potential association between FEMs and myopia development. In this article we hypothesized that abnormal fixation movements would result in disturbed spatiotemporal and defocus visual signal, abnormal longitudinal chromatic aberration, amplified eye-growth signal and extraocular muscle pressure, thereby inducing myopia development. In order to dissect any association between FEMs and myopia, further work is required to prospectively investigate the characteristics of FEMs during development and/or in populations affected by myopia or hyperopia. Future studies will be needed to update new understanding of myopia mechanism and propose suggestive prevention measures.