Myopic progression and dark focus variation in optometric students during the first academic year

Background : The aim of this research was to investigate the change in refractive error (RE) of optometric students during their first academic year and whether these changes relate to changes in their dark focus (DF). Method : The RE and DF of 64 students were measured objectively every three months during the first academic year, a total of four times, using a Canon R‐1 infrared optometer. Thirty‐five of the 64 students had an additional RE and DF measurement three weeks immediately after their Summer vacation. Students completed a survey regarding the near work demands they experienced during the Winter break and the teaching semesters. Results : Over nine months, the average RE of the students changed significantly from ?2.22 ± 1.93 (SD) D to ?2.50 ± 2.05 D (p = 0.0002). The rate of myopic progression averaged ?0.37 dioptres per year. Inclusion of measurements taken on 35 students immediately after the Summer vacation showed that their change in RE during the Summer vacation was not significant (p = 0.79). For these subjects, the DF measured immediately after the vacation was significantly lower than the DF measured before the vacation (p = 0.007). The reduction in the DF after the vacations corresponded to a period of relative myopic stability in these subjects. Conclusions : The results of this study suggest that optometric students performing extensive near work are at risk of developing myopia. The variation of their DF values indicates the changing demand for near work during different periods of the year. After Winter and Summer vacations, the DF was lower and the myopic progression was suspended. These findings further support the notion that myopic progression is related to high near work demands and suggest that this progression can be slowed by a period of reduced near work, for example, vacation periods.     

The autonomic control of accommodation and implications for human myopia development: a review

Prolonged nearwork has long been associated with myopia development, however, there is no well described linking mechanism. One theory suggests that if accommodation accuracy during nearwork is not maintained, the defocused retinal image leads to myopia development. Here we review the findings of research aimed at determining whether the autonomic inputs to the ciliary smooth muscle are involved in this type of environmental myopia. We examine whether an autonomic imbalance could be a precursor to axial elongation and the resulting myopia. Accommodation responses, such as tonic accommodation and nearwork-induced accommodative adaptation, as a function of refractive error, are described in relation to an autonomic imbalance model. The collective results of this research point to anomalous accommodation responses, possibly as a result of underlying anomalous autonomic input to the ciliary muscle, being involved in myopia development and progression.     

Ocular biometry and determinants of refractive error in a founder population of European ancestry

Background: The prevalence of myopia is increasing worldwide. Previous studies have found a positive association between myopia, education, and near activities, while others have noted a negative association with outdoor exposure. This study reports refractive error and biometry in a founder population of European ancestry, the Hutterites, and discusses risk factors contributing to myopia.

Methods: Cross-sectional study, including complete eye exams with retinoscopy and biometry.

Results: 939 study participants, ages 6 to 89, were examined. Females were significantly more myopic than males (SE ?0.87 ± 2.07 and ?0.40 ± 1.49 in females and males, respectively, p < 0.0001). Males had significantly longer axial lengths. Females had steeper corneas. This is the first epidemiological report of refractive error among the Hutterites.

Discussion: As a genetically isolated population with a communal lifestyle, the Hutterites present a unique opportunity to study risk factors for myopia. Hutterite females are more myopic than males, a finding which has only been reported in a few other populations. Hutterite children complete compulsory education through the 8th grade, after which women and men assume gender-specific occupational tasks. Men often work outside on the farm, while women engage in more domestic activities inside. These occupational differences likely contribute to the increased myopia comparing females to males, and their uniform lifestyle reduces the impact of potential confounding factors, such as education and income.

Conclusions: The Hutterites are more myopic than most other North American and European populations. Greater time spent doing near work and less time spent outdoors likely explain the increased myopia comparing females to males.     

Physical activity,time spent outdoors,and near work in relation to myopia prevalence,incidence, and progression: An overview of systematic reviews and meta-analyses

Myopia has reached epidemic levels in recent years. Stopping the development and progression of myopia is critical, as high myopia is a major cause of blindness worldwide. This overview aims at finding the association of time spent outdoors (TSO), near work (NW), and physical activity (PA) with the incidence, prevalence, and progression of myopia in children. Literature search was conducted in PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature, Cochrane Database of Systematic Reviews, ProQuest, and Web of Science databases. Systematic reviews (SR) and meta-analyses (MA) on the TSO, NW, and PA in relation to myopia were reviewed. Methodological nature of qualified studies were evaluated utilizing the Risk of Bias in Systematic Review tool. We identified four SRs out of which three had MA, which included 62 unique studies, involving >1,00,000 children. This overview found a protective trend toward TSO with a pooled odds ratio (OR) of 0.982 (95% confidence interval (CI) 0.979–0.985, I² = 93.5%, P < 0.001) per extra hour of TSO every week. A pooled OR 1.14 (95% CI 1.08–1.20) suggested NW to be related to risk of myopia. However, studies associating myopia with NW activities are not necessarily a causality as the effect of myopia might force children to indoor confinement with more NW and less TSO. PA presented no effect on myopia. Though the strength of evidence is less because of high heterogeneity and lack of clinical trials with clear definition, increased TSO and reduced NW are protective against myopia development among nonmyopes.     

Myopia and visual acuity impairment: a comparative study of Greek and Bulgarian school children

Purpose:  To compare the proportions of school children with myopia and impaired visual acuity in Greece and Bulgaria.
Methods:  A sample of 898 children, aged 10–15 years, was selected from two primary and two secondary schools in a Greek city (Heraklion), and one primary and secondary school in a Bulgarian city (Stara Zagora). Five hundred and eighty eight children were Greek (65.5%, mean age 12.5 ± 0.08 years) and 310 Bulgarian (34.5%, age 12.4 ± 0.07 years). VA was assessed with the habitual refractive correction. Refractive error was measured in the absence of cycloplegia using an auto-refractor.
Results:  The percentage of children, tested with their habitual refractive correction, with decimal VA <0.5 in at least one eye was 11.7% (95% CI 9.1–14.3%) for Greek and 5.2% (95% CI 2.7–7.6%) for Bulgarian pupils. The percentage of myopic children also differed between the two countries with the proportion with myopic refractive error ≤−0.75 D and decimal VA <0.8 at primary school level being 14.1% and 28.9% in Stara Zagora and Heraklion respectively and 13.0% and 46.9% (95% CI 18.2–29.2%, p  < 0.0001) at secondary school level. Among the myopic pupils only 35.8% used corrective spectacles in Stara Zagora, compared to 70.7% of the children in Heraklion. Finally, myopia appeared more prevalent in female adolescents with the effect being statistically significant only for Greek children (55% vs 40% of males, p  = 0.015).
Conclusions:  The increased proportion of myopic children in Heraklion, compared to Stara Zagora, may arise from a number of environmental and socio-economic factors, which need to be further investigated in order to understand the differences observed among European populations.     

Accommodation function comparison following use of contact lens for orthokeratology and spectacle use in myopic children: a prospective controlled trial

AIM: To study effects of orthokeratology (Ortho-k) on accommodation function in myopic children. METHODS: A prospective, non-randomized, case-control study was performed from September to October 2016. Eighty-three children with myopia were divided into two groups. One group was treated with the rigid contact lens for overnight Ortho-k, and the other was treated with single-vision spectacle lens (SVL). Accommodation function were assessed by accommodative amplitude (AA), accommodative sensitivity (AS), accommodative lag (Lag), negative relative accommodation (NRA), and positive relative accommodation (PRA) before and 1, 3, 6 and 12mo after treated. RESULTS: Totally 72 myopic children were finished the follow-up: 37 in Ortho-k group and 35 in SVL group. Wearing time had a significant effect on AA, AS, Lag, and NRA of myopic children in two groups (all P<0.05). Meanwhile, there was an interaction effect between wearing time and wearing types (FAA=5.3, FAS=45.5, FLag=7.0, FNRA=3.7, all P<0.05). However, the between-group difference of AA (F=0.1), AS (F=3.2), Lag (F=1.1), NRA (F=0.3), and PRA (F=0.1) showed no significance. AA, AS, NRA, Lag and PRA were improved significantly in Ortho-k group within 1 to 6mo after wearing. CONCLUSION: Wearing Ortho-k can improve the accommodation function of myopic children, which might be one of the mechanisms for myopia control.     

Refractive, biometric and topographic changes among Portuguese university science students: a 3-year longitudinal study

PURPOSE: The aim of this study was to investigate the changes in refractive, biometric and topographic ocular parameters among university students in Portugal during a 3-year period. METHODS: A 3-year longitudinal study comprised 118 Portuguese university students from the School of Science (34 males and 84 females; mean age 20.6 +/- 2.3 years). Ocular refraction, corneal curvature (CR) and eccentricity, and A-scan biometry were conducted under cycloplegia. The sphero-cylindrical refractive results were converted into vector representations (M, J(0) and J(45)) for statistical analysis. Myopia was defined as M < or = -0.50 D, emmetropia as M > -0.50 D and < +0.50 D and hyperopia as M > or = +0.50 D. RESULTS: At the beginning of the study sphero-cylindrical refraction (M) ranged from -6.75 to +3.00 D, with a mean value of 0.23 +/- 1.46 D [mean +/- standard deviation (S.D.)]. Eighty-three students presented astigmatism with a mean value (+/-S.D.) of -0.52 +/- 0.41 D, and a maximum of -2.25 D. After 3 years the mean refractive change for the M component was -0.29 +/- 0.38 D (p < 0.001) and non-significant changes of 0.02 +/- 0.16 D (p = 0.281) for the J(0) component and 0.01 +/- 0.09 D (p = 0.784) for the J(45) component. Prevalence of myopia increased by 5.1%, while the prevalence of hyperopia decreased by 9.4%. Myopia progression > or =0.5 D was observed in 22% of the population. Axial length, vitreous chamber depth and lens thickness increased significantly while anterior chamber depth and central CR did not change significantly. CONCLUSIONS: This study shows a change in refraction towards myopia accompanied by a vitreous chamber elongation in a Portuguese population comprising science students during the first three years of their university course. Younger students were more likely to show clinically significant myopia progression.     

Femtosecond (FS) laser vision correction procedure for moderate to high myopia: a prospective study of ReLEx® flex and comparison with a retrospective study of FS‐laser in situ keratomileusis

Purpose: To present our initial clinical experience with ReLEx^® flex (ReLEx) for moderate to high myopia. We compare efficacy, safety and corneal higher‐order aberrations after ReLEx with femtosecond laser in situ keratomileusis (FS‐LASIK). Methods: Prospective study of ReLEx compared with a retrospective study of FS‐LASIK. ReLEx is a new keratorefractive procedure, where a stromal lenticule is cut by a femtosecond laser and manually extracted. Forty patients were treated with ReLEx on both eyes. A comparable group of 41 FS‐LASIK patients were retrospectively identified. Visual acuity, spherical equivalent (SE) and corneal tomography were measured before and 3 months after surgery. Results: Preoperative SE averaged ?7.50 ± 1.16 D (ReLEx) and ?7.32 ± 1.09 D (FS‐LASIK). For all eyes, mean corrected distance visual acuity remained unchanged in both groups. For eyes with emmetropia as target refraction, 41% of ReLEx and 61% of FS‐LASIK eyes had an uncorrected distance visual acuity of logMAR ≤ 0.10 at day 1 after surgery, increasing to, respectively, 88% and 69% at 3 months. Mean SE was ?0.06 ± 0.35 D 3 months after ReLEx and ?0.53 ± 0.60 D after FS‐LASIK. The proportion of eyes within ±1.00 D after 3 months was 100% (ReLEx) and 85% (FS‐LASIK). For a 6.0‐mm pupil, corneal spherical aberrations increased significantly less in ReLEx than FS‐LASIK eyes. Conclusions: ReLEx is an all‐in‐one femtosecond laser refractive procedure, and in this study, results were comparable to FS‐LASIK. Refractive predictability and corneal aberrations at 3 months seemed better than or equal to FS‐LASIK, whereas visual recovery after ReLEx was slower.     

Efficacy and safety of atropine at different concentrations in prevention of myopia progression in Asian children: a systematic review and Meta-analysis of randomized clinical trials

AIM: To assess the efficacy versus the adverse effects of various concentrations of atropine in the prevention of myopia in Asian children. METHODS: Databases (PubMed, EMBASE, the Cochrane Library and Web of science) were comprehensively searched from inception to April 2022. Types of studies included were randomized clinical trials (RCTs). The published languages were limited to English. Two researchers assessed the quality of included studies independently using Cochrane risk of bias tool based on the Cochrane Handbook for Systematic Reviews of Interventions. Funnel plots and Egger’s test were used for detection of publication bias. Meta-analyses were conducted using STATA (version 15.0; StataCorp). RESULTS: A total of 15 RCTs involving 2268 patients were included in the study. In the atropine group, spherical equivalent progressed at a significantly lower rate [weighted mean difference (WMD)=0.39, 95% confidence interval (CI): 0.23, 0.54] than in the control group. A WMD of 0.15 mm was associated with less axial elongation (95%CI -0.19, -0.10). Different doses showed statistically significant differences (P<0.05) and an improved effect could result from a higher concentration. Changes in photopic pupil size and mesopic pupil size in atropine group is 0.70 mm (95%CI: 0.33, 1.06) and 0.38 mm (95%CI: 0.22, 0.54) more than the control group. In the present Meta-analysis, no changes in accommodative amplitude (AA) were associated with atropine administration. Atropine administration increased the risk of adverse effects by 1.37 times. CONCLUSION: Concentrations of less than 1% atropine are able to effectively retard diopter and axis growth of myopia in Asian children in a dose-dependent manner. Meanwhile, it caused pupil enlargement, but induced no change in the AA within this range. Further study is required to determine the dosage needed to achieve maximum efficacy and minimal side effects.     

Relationship between higher-order aberrations and myopia progression in schoolchildren:a retrospective study

AIM:To investigate the relationship between higher-order aberration (HOA) and myopic progression in school children.METHODS:Between April 23, 2011 and August 29, 2011 in the children’s myopia outpatient clinic of the West China Hospital of Sichuan University, 148 eyes of 74 schoolchildren were reviewed. HOAs for a 6-mm pupil were measured with an aberrometer. Myopic progression rate was defined according to the change in spherical equivalent refraction (SER) divided by the time span (years). Subjects with myopic progression rate of ≥0.50 diopters (D) were classified as the ‘fast’ group and the subjects with myopic progression rate of <0.50D were classified as the ‘slow’ group. A retrospective study was conducted to compare HOA between the two groups, using root mean square (RMS) values and Zernike coefficients.RESULTS: The RMS values of HOA (t=2.316, P=0.02), HOA without Z4⁰ (t=2.224, P=0.03), third-order aberrations (t’=2.62, P=0.01), and coma (t’=2.49, P=0.01) were significantly higher in the fast group than those in the slow group. The individual Zernike coefficients of Z3^-1 (t=-2.072, P=0.04) and Z5¹ (Z =-2.627, P=0.01) displayed statistically significant differences between the two groups. Significant correlations were found between the RMS values of HOA (r=0.193, P=0.019), RMS values of HOA without Z4⁰ (r=0.23, P =0.005), RMS values of coma (r=0.235, P=0.004), RMS values of third-order aberrations (r=0.243, P =0.003), and the progression rate.CONCLUSION:Our results provide evidence of a relationship between HOA and myopic progression. In a future prospective longitudinal study, we aim to verify whether HOA is a risk factor for myopic progression.     

Prevalences and causes of vision impairment in elderly Chinese: a socioeconomic perspective of a comparative report nested in Jiangsu Eye Study

AIM: To survey the prevalence and causes of visual impairment/blindness among elderly Chinese from different socioeconomic status in community-based design. METHODS: Cluster-sampling randomly selected residents from Binhu and Funing District, two areas representing different socioeconomic levels in China with Binhu in an advanced status and Funing in less-developed area. The participants subjected to ophthalmic examination. The presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) were recorded. Visual impairment and blindness were defined according to World Health Organization criteria. The causes of visual impairment/blindness were identified by ophthalmic examination and/or questionnaire. The socioeconomic status included the per capita gross domestic product, numbers of hospital with ophthalmic service and the number of ophthalmologists per 1 million residents. RESULTS: We successfully included 12 867 participants form 2 areas in this study. The prevalence of PVA impairment (<20/63 to ≥20/400) in the better eye was 5.4% in Binhu and 23.6% in Funing, while the prevalence of blindness (<20/400) was 0.9% in Binhu and 2.3% in Funing. With BCVA, the prevalence of visual impairment was 2.4% in Binhu and 6.4% in Funing, while the prevalence of blindness was 0.8% in Binhu and 1.6% in Funing. The participants with older age and female gender had higher prevalence in visual impairment and blindness. The highest prevalences of vision impairment and blindness evaluated by BCVA at >80y age group reached 20.4% and 6.3% respectively. The prevalences of vision impairment and blindness evaluated by BCVA were 3.5% and 1.0% in male and 5.0% and 1.3% in female. The above differences were statistically significant (P<0.05). The predominant causes of visual impairment and blindness were cataract, retinal disorders and uncorrected refractive error in both areas. The socioeconomic status was associated with visual impairment and blindness. CONCLUSION: This community-based study build a sufficient sample size for an ophthalmic survey. Our data show the disparities on socioeconomic development and genders in visual impairment and blindness in China. Special emphasis of ophthalmic service should be placed on females and less-developed area.     

Loss of chromatic sensitivity in AMD and diabetes: a comparative study

Background: Abnormalities in rod and cone photoreceptor morphology have been reported in normal aging retinas in the absence of known pathology and have been taken as an indicator of susceptibility to retinal disease. Some loss of visual performance may therefore precede retinal structural changes that can be detected reliably using conventional fundus imaging techniques. Red/green (RG) and yellow/blue (YB) colour discrimination thresholds are sensitive measures of normal retinal function and poor YB discrimination is often taken as an indicator of retinal disease, though it is generally acknowledged that RG loss is also present in most cases of acquired deficiency. Although structural changes in age‐related macular degeneration (AMD) and diabetes share some similarities, significant differences remain and this may result in different patterns of RG and YB loss. Aim: The aim of this study was to quantify and compare the severity of RG and YB loss of chromatic sensitivity in patients with AMD and diabetes. Methods: Patients with varying severity of AMD and diabetes and normal subjects of similar age were recruited for the study. RG and YB colour detection thresholds were measured in the two groups of patients and the control group, using the Colour Assessment and Diagnosis (CAD) test. Results: Each AMD subject investigated showed significant, but unequal loss of YB and RG chromatic sensitivity, with YB discrimination showing the greatest loss. Diabetic subjects also exhibited reduced chromatic sensitivity, but with almost equal and highly correlated RG and YB thresholds (R² = 0.99). The severity of colour vision loss measured with the CAD test also correlates well with a clinical classification index of disease progression in AMD, and with the level of hyperglycaemic control in diabetes. Conclusions: These findings suggest that accurate measurements of RG and YB colour thresholds can provide a sensitive measure of functional change in diseases of the retina with patterns of loss that differ significantly in AMD and diabetes.