Myopia onset and progression: can it be prevented?

The Effect of Low-Dose Atropine on Alpha Ganglion Cell Signaling in the Mouse Retina

Low-dose atropine helps to control myopia progression with few side effects. However, the impact of atropine, a non-selective muscarinic Acetylcholine (ACh) receptor antagonist, on retinal ganglion cells (RGCs) remains unclear. After immersing the cornea and adjacent conjunctiva of enucleated eyes in 0.05% (approximately 800 μM) atropine solution for 30 min, the atropine concentration reached in the retina was below 2 μM. After direct superfusion of the retina with 1 μM atropine (considering that the clinical application of 0.05% atropine eye drops will be diluted over time due to tear flow for 30 min), no noticeable changes in the morphology of ON and OFF alpha RGCs (αRGCs) were observed. Atropine affected the light-evoked responses of ON and OFF αRGCs in a dose- and time-dependent fashion. Direct application of less than 100 μM atropine on the retina did not affect light-evoked responses. The time latency of light-induced responses of ON or OFF αRGCs did not change after the application of 0.05–100 μM atropine for 5 min. However, 50 μM atropine extended the threshold of joint inter-spike interval (ISI) distribution of the RGCs. These results indicated that low-dose atropine (<0.5 μM; equal to 1% atropine topical application) did not interfere with spike frequency, the pattern of synchronized firing between OFF αRGCs, or the threshold of joint ISI distribution of αRGCs. The application of atropine unmasked inhibition to induce ON responses from certain OFF RGCs, possibly via the GABAergic pathway, potentially affecting visual information processing.

Proteomic analysis of Exosomes derived from the Aqueous Humor of Myopia Patients

Objectives: Myopia is the most common refractive vision disorder. In recent years, several studies have suggested that the alteration of the exosomal protein levels in the aqueous humor (AH) is associated with the development of several eye diseases. Therefore, we aimed to explore the exosomal protein profile of the AH from myopia patients. Methods: Exosomes were isolated from the AH. The quality, concentration, and size distribution of exosomes for each patient were measured using nanoparticle tracking analysis system. Then, the exosomal proteins were purified and digested by trypsin for liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Results: There was no significant difference observed between the myopia and control when comparing the concentration and size distribution of exosomes in the AH for each sample. Based on LC-MS/MS analysis, myopia patients had higher and more complex exosomal peptide content. We found two proteins that were common in AH exosomes and eight proteins that were highly expressed in the myopia group. Conclusions: Our results provide pioneering findings for the exploration of the exosomal protein profile in myopia development. Further studies may provide significant information for the diagnosis, clinical treatment, and prognosis of myopia.

Effects of scleral collagen crosslinking with different carbohydrate on chemical bond and ultrastructure of rabbit sclera: Future treatment for myopia progression

Background

Myopia is the most common ocular disorder and is mainly caused by axial elongation of the sclera. If the stiffness of sclera increased, it can inhibit myopia progression. The aim of this study is to compare the effect of the collagen crosslinking with different types and concentrations of carbohydrates on chemical bond and ultrastructural change of rabbit sclera.

Methods

Nine New Zealand white rabbits were treated with five, sequential sub-Tenon injections of 0.15 mL solutions of ribose, sucrose, and glycogen of 0.1, 0.2 and 0.4 M concentration at the right eye over 14 days. Ten weeks after the last injection, the rabbits were sacrificed and chemical bond and ultrastructural changes were compared with those of the untreated left sclera using Raman spectroscopy, atomic force microscopy (AFM), and histology.

Results

Raman spectroscopy of the control and cross-linked rabbit sclera tissue revealed different types of collagen interactions. Raman shift of 919 cm^-1 (C-C stretching and vibration of the proline ring in collagen) was the highest in ribose, followed by sucrose and glycogen. Total energy intensity was also highest in ribose, followed by sucrose and glycogen, and showed a tendency to increase at higher concentrations. AFM revealed interlocking arrangements of collagen fibrils. The collagen fibril diameter was 105.6 ± 21.2 nm, 109.4 ± 28.8 nm, 113.1 ± 30.8 nm and 137.6 ± 25.3 nm for control group, 0.4 M glycogen, sucrose, and ribose, respectively. Histology indicated increased density of the collagen bundle and no increase in inflammatory cell recruitment compared to control at high concentrations of ribose.

Conclusions

Scleral crosslinking using glycation increased the scleral biomechanical rigidity and these results were particularly pronounced in ribose. Scleral crosslinking using glycation may be a promising method for inhibiting high myopia progression.

Benefits of Outdoor Sports for Society. A Systematic Literature Review and Reflections on Evidence

The combination of physical activity and being in nature is recognized as providing a range of significant benefits. The objective of this literature review was to compile an overview of the social benefits and costs associated with outdoor sports within the academic literature and to reflect on the quality of underlying evidence that supports the relationship. A systematic review was carried out with seven partners from different European countries, including Bulgaria, France, Germany, United Kingdom, Italy, Portugal, and Spain. From a total of 17,560 studies identified, 133 studies were selected with relevant data extracted to standardized forms. The selected studies have been analyzed with qualitative research methods. A meta-analysis could not be conducted due to the heterogeneity of the study designs and outcome measures. As a result, the review gives an overview of the social impacts associated with outdoor sports which have been clustered to six broad categories: physical health, mental health and wellbeing, education and lifelong learning, active citizenship, crime reduction, and anti-social behavior, as well as additional benefits. The review furthermore revealed gaps in the evidence base which are especially notable in the long-term effects that outdoor sports can have on personal and social development.

Outdoor physical activity bears multiple benefits to health and society

INTRODUCTION

Cutting-edge technologies and the rapid urbanization have led to several advantages for mankind and society. However such benefits have been accompanied with the alarming diffusion of sedentary lifestyle disorders, metabolic diseases, major depression and socialization problems, affecting global economy dramatically. The pandemic expansion of chronic diseases is associated with physical inactivity. During the last decade, numerous cities and organizations worldwide have started to adopt strategies aimed at improving outdoor physical activity levels in city residents.

EVIDENCE ACQUISITION

A systematic review focusing on the effects of regular outdoor sports and physical activities across all ages was conducted through multiple databases, according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) standards.

EVIDENCE SYNTHESIS

Performing outdoor sports and physical activities may bear social, psychological and physiological benefits. Preventive effects are similarly documented in youth and seniors towards several morbid conditions: vitamin D deficiency, multiple sclerosis, osteoporosis and myopia.

CONCLUSIONS

Giving the beneficial effects of outdoor sports and physical activities, promotion strategies should be strongly advocated and developed nationally and globally. Likewise, dedicated research areas should inspire guidelines for the promotion of various outdoor activities - a good practice for the social scenario and the healthcare system.

Breastfeeding and myopia: A cross-sectional study of children aged 6-12 years in Tianjin, China

This study aimed to determine whether an association existed between breastfeeding and myopia in children aged 6-12 years in Tianjin, China, using a cross-sectional study of 527 children. The spherical equivalent refraction (SER) and axial length (AL) were determined by ocular examination, and information regarding the children's demographics, breastfeeding history and other myopia-related risk factors were investigated using a questionnaire. The myopia prevalence rate, mean SER, and mean AL were 53.9%, -0.99 ± 1.69 D, and 23.56 ± 1.11 mm, respectively. In total, 442 (83.9%) participants were breastfed; among the breastfed participants, 132 (29.9%) were breastfed <6 months. Children who were breastfed were less likely to have myopia (breastfeeding duration <6 months: OR = 0.399, P = 0.011; >6 months: OR = 0.502, P = 0.033, multiple logistical regression). The mean SER of children breastfed <6 months was 0.653 D more hyperopic than that of non-breastfed children (P = 0.008, multiple linear regression). No significant association was observed between breastfeeding and AL. In conclusion, breastfeeding was associated with a decreased risk of myopia among children aged 6-12 years in Tianjin. Breastfeeding during the first 6 months of infancy was associated with more hyperopic SER. Furthermore, breastfeeding was associated with myopic refraction and was not related to AL, and this association could exist in childhood.

Myopia Progression Risk: Seasonal and Lifestyle Variations in Axial Length Growth in Czech Children

The growth in the prevalence of myopia leads to the growth of socioeconomic stress in society. It is important to detect any potential risk factors leading to myopia onset and progression. Among the potential risk factors, the lack of natural daylight exposure and the lack of the physical activity together with excess of near-work activities in children are the most prevalent. In the study, the axial length growth depending on the season and the type of behaviour was measured. The assessment was performed in 12-year-old children, 398 eyes of whom were included and measured during the winter and summer period. The children were categorized by the amount of time spent on near-work, physical, and outdoor activity. Results. Statistically significantly higher (p < 0.0001) axial length growth was observed during the winter period. Statistically significantly (p < 0.0001) more frequently, the eyeball growth has been proved during the winter season. According to the way of spending leisure time, no statistically significant difference was reported within the individual subgroups in the development of the eyeball length during the observed period. However, statistically significant differences were ascertained in the eyeball initial length within various groups. Conclusion. The lack of daylight exposure may lead to myopia progression.

Factors related to axial length elongation and myopia progression in orthokeratology practice

Purpose

To investigate which baseline factors are predictive for axial length growth over an average period of 2.5 years in a group of children wearing orthokeratology (OK) contact lenses.

Methods

In this retrospective study, the clinical records of 249 new OK wearers between January 2012 and December 2013 from the contact lens clinic at the Eye and ENT Hospital of Fudan University were reviewed. The primary outcome measure was axial length change from baseline to the time of review (July-August 2015). Independent variables included baseline measures of age at initiation of OK wear, gender, refractive error (spherical equivalent), astigmatism, average keratometry, corneal toricity, central corneal thickness, white-to-white corneal diameter, pupil size, corneal topography eccentricity value (e-value), intraocular pressure (IOP) and total time in follow-up (months total). The contributions of all independent variables on axial length change at the time of review were assessed using univariate and multivariable regression analyses.

Results

Univariate analyses of the right eyes of 249 OK patients showed that smaller increases in axial length were associated with older age at the onset of OK lens wear, greater baseline spherical equivalent myopic refractive error, less time in follow-up and a smaller e-value. Multivariable analyses of the significant right eye variables showed that the factors associated with smaller axial length growth were older age at the onset of OK lens wear (p<0.0001), greater baseline spherical equivalent myopic refractive error (p = 0.0046) and less time in follow-up (p<0.0001).

Conclusions

The baseline factors demonstrating the greatest correlation with reduced axial length elongation during OK lens wear in myopic children included greater baseline spherical equivalent myopic refractive error and older age at the onset of OK lens wear.

Refractive plasticity of the developing chick eye: a summary and update

PURPOSE

To summarize the OPO 1992 Classic Paper: Refractive plasticity of the developing chick eye (12: 448-452) and discuss recent findings in refractive development.

SUMMARY AND RECENT FINDINGS

The classic paper shows that when lightweight plastic goggles with rigid contact lens inserts are applied to the eyes of newly hatched chicks, the eye responds accurately to defocus between -10 and +20 D, although hyperopia develops more rapidly. While the changes largely are due to change in axial length, high levels of hyperopia are associated with corneal flattening. Also, newly hatched chicks are better able to compensate for the induced defocus than chicks that are 9 days old. In addition, astigmatism of 2-6 D can be produced by applying 9 D toric inducing lenses on the day of hatching, and the most myopic meridian coincides with the power meridian of the inducing lens. This astigmatism appears to be primarily due to corneal toricity. Furthermore, the greatest magnitude was produced when the plano meridian of the inducing lens was placed 45° from the line of the palpebral fissure. Since our publication in 1992, it has been shown that similar results can be produced in a variety of species, including; tree shrews, marmosets, monkeys and fish. Considerable effort has been spent in trying to determine what the eye uses, if not the brain, as the signal to the sign of the defocus. Accommodation, chromatic aberration, diurnal variation, astigmatism and higher order monochromatic aberrations have all been considered. Choroidal thinning and thickening play a role in myopia and hyperopia development, respectively, in chicks. High light levels (15,000 lux) increase the rate at which chicks compensate for positive lenses and decrease the compensation rate for negative lenses. However these light levels do not prevent the eye from fully compensating for either type of lens. It has also been shown that brief periods of normal vision prevent the development of form deprivation myopia. Finally, the importance of the peripheral retina in refractive development has been explored and lenses designed to reduce relative peripheral hyperopia have resulted in variable effects as far as myopia control is concerned.

CONCLUSIONS

A growing body of evidence, from both animal models and human clinical trials indicates that the development of myopia is related both to genetics and environment / lifestyle. Nevertheless, we are far from understanding how this interaction takes place.

Five-Year Clinical Trial on Atropine for the Treatment of Myopia 2: Myopia Control with Atropine 0.01% Eyedrops

PURPOSE

To compare the safety and efficacy of different concentrations of atropine eyedrops in controlling myopia progression over 5 years.

DESIGN

Randomized, double-masked clinical trial.

PARTICIPANTS

A total of 400 children originally randomized to receive atropine 0.5%, 0.1%, or 0.01% once daily in both eyes in a 2:2:1 ratio.

METHODS

Children received atropine for 24 months (phase 1), after which medication was stopped for 12 months (phase 2). Children who had myopia progression (≥-0.50 diopters [D] in at least 1 eye) during phase 2 were restarted on atropine 0.01% for a further 24 months (phase 3).

MAIN OUTCOME MEASURES

Change in spherical equivalent and axial length over 5 years.

RESULTS

There was a dose-related response in phase 1 with a greater effect in higher doses, but an inverse dose-related increase in myopia during phase 2 (washout), resulting in atropine 0.01% being most effective in reducing myopia progression at 3 years. Some 24%, 59%, and 68% of children originally in the atropine 0.01%, 0.1%, and 0.5% groups, respectively, who progressed in phase 2 were restarted on atropine 0.01%. Younger children and those with greater myopic progression in year 1 were more likely to require re-treatment. The lower myopia progression in the 0.01% group persisted during phase 3, with overall myopia progression and change in axial elongation at the end of 5 years being lowest in this group (-1.38±0.98 D; 0.75±0.48 mm) compared with the 0.1% (-1.83±1.16 D, P = 0.003; 0.85±0.53 mm, P = 0.144) and 0.5% (-1.98±1.10 D, P < 0.001; 0.87±0.49 mm, P = 0.075) groups. Atropine 0.01% also caused minimal pupil dilation (0.8 mm), minimal loss of accommodation (2-3 D), and no near visual loss compared with higher doses.

CONCLUSIONS

Over 5 years, atropine 0.01% eyedrops were more effective in slowing myopia progression with less visual side effects compared with higher doses of atropine.

Tamponade or filling effect: changes of forces in myopic eyes

Myopia is the most common ocular abnormality. Its high and growing prevalence has contributed to a recent surge in surgical interest in the disorder, since retinal detachment in eyes with high myopia differs from that in emmetropic eyes or eyes with low myopia. The myopic eye, because of its specific anatomy, poses special challenges that need to be overcome to ensure the appropriate use of vitreous substitutes. However, intraocular tamponades have shown great potential for revolutionizing retinal detachment surgery and vitreomacular surgery in general in myopic eyes. We provide an updated review of the clinical use of vitreous substitutes in the myopic eye, paying particular attention to analyzing the ideal function of endotamponade agents and comparing the effects of these agents on the physical and biological properties of the eye.

Reducing visual deficits caused by refractive errors in school and preschool children: results of a pilot school program in the Andean region of Apurimac, Peru

Background

Refractive error is defined as the inability of the eye to bring parallel rays of light into focus on the retina, resulting in nearsightedness (myopia), farsightedness (Hyperopia) or astigmatism. Uncorrected refractive error in children is associated with increased morbidity and reduced educational opportunities. Vision screening (VS) is a method for identifying children with visual impairment or eye conditions likely to lead to visual impairment.

Objective

To analyze the utility of vision screening conducted by teachers and to contribute to a better estimation of the prevalence of childhood refractive errors in Apurimac, Peru.

Design

A pilot vision screening program in preschool (Group I) and elementary school children (Group II) was conducted with the participation of 26 trained teachers. Children whose visual acuity was<6/9 [20/30] (Group I) and≤6/9 (Group II) in one or both eyes, measured with the Snellen Tumbling E chart at 6 m, were referred for a comprehensive eye exam. Specificity and positive predictive value to detect refractive error were calculated against clinical examination. Program assessment with participants was conducted to evaluate outcomes and procedures.

Results

A total sample of 364 children aged 3–11 were screened; 45 children were examined at Centro Oftalmológico Monseñor Enrique Pelach (COMEP) Eye Hospital. Prevalence of refractive error was 6.2% (Group I) and 6.9% (Group II); specificity of teacher vision screening was 95.8% and 93.0%, while positive predictive value was 59.1% and 47.8% for each group, respectively. Aspects highlighted to improve the program included extending training, increasing parental involvement, and helping referred children to attend the hospital.

Conclusion

Prevalence of refractive error in children is significant in the region. Vision screening performed by trained teachers is a valid intervention for early detection of refractive error, including screening of preschool children. Program sustainability and improvements in education and quality of life resulting from childhood vision screening require further research.