Onset Of Myopia Research Articles

Clinical management of progressive myopia.

Myopia has been increasing in prevalence throughout the world, reaching over 90% in some East Asian populations. There is increasing evidence that whereas genetics clearly have an important role, the type of visual environment to which one is exposed to likely influences the onset, progression, and cessation of myopia. Consequently, attempts to either modify the environment or to reduce the exposure of the eye to various environmental stimuli to eye growth through the use of various optical devices are well under way at research centers around the globe. The most promising of current treatments include low-percentage atropine, bifocal soft contact lenses, orthokeratology, and multifocal spectacles. These methods are discussed briefly and are then categorized in terms of their expected degree of myopia progression control. A clinical strategy is presented for selecting the most effective treatment for the appropriate type of patient at the optimal stage of refractive development to achieve the maximum control of myopia progression.

Re: Wu et al.: Outdoor Activity during Class Recess Reduces Myopia Onset and Progression in School Children (Ophthalmology 2013;120:1080-1085)

Re: Wu et al.: Outdoor Activity during Class Recess Reduces Myopia Onset and Progression in School Children (Ophthalmology 2013;120:1080-1085)

Effect of correction of aberration dynamics on chaos in human ocular accommodation

We used adaptive optics to determine the effect of monochromatic aberration dynamics on the level of chaos in the accommodation control system. Four participants viewed a stationary target while the dynamics of their aberrations were either left uncorrected, defocus was corrected, or all aberrations except defocus were corrected. Chaos theory analysis was used to discern changes in the accommodative microfluctuations. We found a statistically significant reduction in the chaotic nature of the accommodation microfluctuations during correction of defocus, but not when all aberrations except defocus were corrected. The Lyapunov exponent decreased from 0.71 ± 0.07 D/s (baseline) to 0.55 ± 0.03 D/s (correction of defocus fluctuations). As the reduction of chaos in physiological signals is indicative of stress to the system, the results indicate that for the participants included in this study, fluctuations in defocus have a more profound effect than those of the other aberrations. There were no changes in the power spectrum between experimental conditions. Hence chaos theory analysis is a more subtle marker of changes in the accommodation control system and will be of value in the study of myopia onset and progression.

Spherical Aberration and the Sign of Defocus

Visual sensing of the sign of defocus is important not only for the rapid control of accommodation but also for regulating the slower long-term growth of the eye. We examined the possibility that ocular spherical aberration (SA) elicits a sign of defocus by optical modeling of image formation using the principles of physical optics. Retinal image contrast, as measured by the area under the visually weighted modulation-transfer function, depends on both the magnitude and the sign of defocus relative to the sign of the SA. Image contrast is greater for hyperopic blur than for myopic blur when SA is positive and vice versa when SA is negative. When coupled with Wallman's hypothesis that retinal activity caused by image contrast inhibits eye growth, these results provide a testable hypothesis to account for myopia progression. For example, we suggest that hyperopic blur is a risk factor for myopia progression only when the eye has a negative SA because that is the combination leading to relatively low contrast in the defocused retinal image. Because the likelihood of a negative SA increases with accommodation, avoiding long hours of near work in the presence of accommodative lag may help prevent the onset and progression of myopia.

Factors Preventing Myopia Progression with Orthokeratology Correction

To examine which baseline measurements constitute predictive factors for axial length growth over 2 years in children wearing orthokeratology contact lenses (OK) and single-vision spectacles (SV). Sixty-one children were prospectively assigned to wear either OK (n = 31) or SV (n = 30) for 2 years. The primary outcome measure (dependent variable) was axial length change at 2 years relative to baseline. Other measurements (independent variables) were age, age of myopia onset, gender, myopia progression 2 years before baseline and baseline myopia, anterior chamber depth, corneal power and shape (p value), and iris and pupil diameters as well as parental refraction. The contribution of all independent variables to the 2-year change in axial length was assessed using univariate and multivariate regression analyses. After univariate analyses, smaller increases in axial length were found in the OK group compared to the SV group in children who were older, had earlier onset of myopia, were female, had lower rate of myopia progression before baseline, had less myopia at baseline, had longer anterior chamber depth, had greater corneal power, had more prolate corneal shape, had larger iris diameter, had larger pupil sizes, and had lower levels of parental myopia (all p < 0.05). In multivariate analyses, older age and greater corneal power were associated with smaller increases in axial length in the OK group (both p < 0.05), whereas in SV wearers, smaller iris diameter was associated with smaller increases in axial length (p = 0.021). Orthokeratology is a successful treatment option in controlling axial elongation compared to SV in children of older age, had earlier onset of myopia, were female, had lower rate of myopia progression before baseline, had lower myopia at baseline, had longer anterior chamber depth, had greater corneal power, had more prolate corneal shape, had larger iris and pupil diameters, and had lower levels of parental myopia.

Astigmatism and Myopia in Tohono O’odham Native American Children

To describe change in spherical equivalent (M) in a longitudinal sample of Tohono O'odham students ages 3 to 18 years and to test the hypothesis that astigmatism creates complex cues to emmetropization, resulting in increased change in M in the direction of increasing myopia and increased occurrence of myopia. Subjects were 777 Tohono O'odham Native American children on whom cycloplegic right eye autorefraction was measured on at least two study encounters between ages 3 and 18 years (first encounter prior to age 5.5 years, final encounter ≥3 years later). Regression lines were fit to individual subjects' longitudinal M data to estimate rate of change in M (regression slope, D/yr). Regression was also used to predict if a subject would be myopic (≤-0.75 D M) by age 18 years. Analysis of covariance was used to assess the relation between M slope and magnitude of baseline M and astigmatism. Chi-square analyses were used to assess the relation between predicted myopia onset and magnitude of baseline M and astigmatism. Mean M slope was significantly more negative for hyperopes (M ≥ +2.00) than for myopes (M ≤ -0.75) or for subjects neither hyperopic nor myopic (NHM, M > -0.75 and < +2.00), but there was no significant difference between the myopic and NHM groups. Chi-square analysis indicated that final myopia status varied across level of baseline astigmatism. Subjects with high astigmatism were more likely to be predicted to have significant myopia by age 18 years. The association between greater shift in M towards myopia with age in subjects who were hyperopic at baseline is consistent with continued emmetropization in the school years. Results regarding predicted myopia development imply that degradation of image quality due to refractive astigmatism creates complex cues to emmetropization, resulting in increased occurrence of myopia.

Myopia onset and progression: can it be prevented?

Myopia is the commonest ocular abnormality and the high and growing prevalence of myopia, especially but not only in Asian populations, as well as its progressive nature in children, has contributed to a recent surge in interest. Such worldwide growing prevalence seems to be associated with increasing educational pressures, combined with life-style changes, which have reduced the time that children spend outdoors. Highly nearsighted people are at greater risk for several vision-threatening problems such as retinal detachments, choroidal neovascularization, cataracts and glaucoma, thus the potential benefits of interventions that can limit or prevent myopia progression would be of remarkable social impact. Our understanding of the regulatory processes that lead an eye to refractive errors is undoubtedly incomplete but has grown enormously in the last decades thanks to the animal studies, observational clinical studies, and randomized clinical trials recently published. In this review we assess the effects of several types of life-style and interventions, including outdoor activities, eye drops, undercorrection of myopia, multifocal spectacles, contact lenses, and refractive surgery on the onset and progression of nearsightedness.

The relationship between anisometropia and amblyopia

This review aims to disentangle cause and effect in the relationship between anisometropia and amblyopia. Specifically, we examine the literature for evidence to support different possible developmental sequences that could ultimately lead to the presentation of both conditions. The prevalence of anisometropia is around 20% for an inter-ocular difference of 0.5D or greater in spherical equivalent refraction, falling to 2-3%, for an inter-ocular difference of 3D or above. Anisometropia prevalence is relatively high in the weeks following birth, in the teenage years coinciding with the onset of myopia and, most notably, in older adults starting after the onset of presbyopia. It has about one-third the prevalence of bilateral refractive errors of the same magnitude. Importantly, the prevalence of anisometropia is higher in highly ametropic groups, suggesting that emmetropization failures underlying ametropia and anisometropia may be similar. Amblyopia is present in 1-3% of humans and around one-half to two-thirds of amblyopes have anisometropia either alone or in combination with strabismus. The frequent co-existence of amblyopia and anisometropia at a child's first clinical examination promotes the belief that the anisometropia has caused the amblyopia, as has been demonstrated in animal models of the condition. In reviewing the human and monkey literature however it is clear that there are additional paths beyond this classic hypothesis to the co-occurrence of anisometropia and amblyopia. For example, after the emergence of amblyopia secondary to either deprivation or strabismus, anisometropia often follows. In cases of anisometropia with no apparent deprivation or strabismus, questions remain about the failure of the emmetropization mechanism that routinely eliminates infantile anisometropia. Also, the chronology of amblyopia development is poorly documented in cases of 'pure' anisometropic amblyopia. Although indirect, the therapeutic impact of refractive correction on anisometropic amblyopia provides strong support for the hypothesis that the anisometropia caused the amblyopia. Direct evidence for the aetiology of anisometropic amblyopia will require longitudinal tracking of at-risk infants, which poses numerous methodological and ethical challenges. However, if we are to prevent this condition, we must understand the factors that cause it to develop.

Age of myopia onset in a British population‐based twin cohort

School-age myopia is becoming more common in Asia and North America; data from the United Kingdom has suggested a significant amount of myopia develops after the age of 17 years. Age of spectacle wear has been used as a proxy of myopia severity in a recent large genome-wide association study. The purpose of this study was to examine the age of onset of spectacle wear in a large British twin cohort, to examine the reliability and reproducibility of self-reported age of onset as a proxy measure of myopia severity, and to see if there is evidence in the UK of a rising prevalence of myopia. Non-cycloplegic autorefraction was performed on over 6000 subjects from the Twins UK cohort, a large, well-characterized volunteer cohort of British, predominantly Caucasian female twins, between 1998 and 2010. Questionnaires asking age of first spectacle wear were conducted in 2003 and 2008. Myopia was defined as worse than or equal to -1.00 Dioptres, and adult onset myopia as occurring on or after the age of 17 years. Autorefractive data was available on 6097 participants at a mean age of 53 years. The mean S.E. was -0.36 D (S.D. 2.67, range -25.13 to +9.38). 1705 subjects (28%) were myopic with a mean refractive error of -3.54 (S.D. 2.51, range -25.13 to -1.00) and the median age of first glasses wear was 15 years (mean 18.4 years, S.D. 12.24, range 0-74). Of those who provided an age at which they first wore glasses in both questionnaire sources (n = 628), there was median difference in response of 0 years (S.D. 7.18, mean 0.7, maximum 53). A statistically significant cohort effect for increased myopia prevalence across a range of age groups between 1998-1999 and 2008-2010 was identified, with myopia prevalence increasing from 27% to 34% in those aged 50-54 and from 16% to 32% in those aged 55-59. Almost half the myopes in this UK-based population wore glasses after the age of 17; further research into adult-onset myopia is required. Although self-reported age of glasses is reproducible and reflects severity, it only explains approximately 15% of the variance of spherical equivalent, so is a rough proxy of refractive error, but still may be useful in large-scale population studies without access to refraction. We have demonstrated a significant cohort effect for increased myopia prevalence in the UK population over a 10-year period.

Genome-Wide Analysis Points to Roles for Extracellular Matrix Remodeling, the Visual Cycle, and Neuronal Development in Myopia

Myopia, or nearsightedness, is the most common eye disorder, resulting primarily from excess elongation of the eye. The etiology of myopia, although known to be complex, is poorly understood. Here we report the largest ever genome-wide association study (45,771 participants) on myopia in Europeans. We performed a survival analysis on age of myopia onset and identified 22 significant associations (), two of which are replications of earlier associations with refractive error. Ten of the 20 novel associations identified replicate in a separate cohort of 8,323 participants who reported if they had developed myopia before age 10. These 22 associations in total explain 2.9% of the variance in myopia age of onset and point toward a number of different mechanisms behind the development of myopia. One association is in the gene PRSS56, which has previously been linked to abnormally small eyes; one is in a gene that forms part of the extracellular matrix (LAMA2); two are in or near genes involved in the regeneration of 11-cis-retinal (RGR and RDH5); two are near genes known to be involved in the growth and guidance of retinal ganglion cells (ZIC2, SFRP1); and five are in or near genes involved in neuronal signaling or development. These novel findings point toward multiple genetic factors involved in the development of myopia and suggest that complex interactions between extracellular matrix remodeling, neuronal development, and visual signals from the retina may underlie the development of myopia in humans.

Outdoor Activity during Class Recess Reduces Myopia Onset and Progression in School Children

The aim of this study was to investigate the effect of outdoor activity during class recess on myopia changes among elementary school students in a suburban area of Taiwan. Prospective, comparative, consecutive, interventional study. Elementary school students 7 to 11 years of age recruited from 2 nearby schools located in a suburban area of southern Taiwan. The children of one school participated in the interventions, whereas those from the other school served as the control group. The interventions consisted of performing a recess outside the classroom (ROC) program that encouraged children to go outside for outdoor activities during recess. The control school did not have any special programs during recess. Data were obtained by means of a parent questionnaire and ocular evaluations that included axial length and cycloplegic autorefraction at the beginning and after 1 year. Five hundred seventy-one students were recruited for this study, of whom 333 students participated in the interventional program, and 238 students were in the control school. At the beginning of the study, there were no significant differences between these 2 schools with regard to age, gender, baseline refraction, and myopia prevalence (47.75% vs. 49.16%). After 1 year, new onset of myopia was significantly lower in the ROC group than in the control group (8.41% vs. 17.65%; P<0.001). There was also significantly lower myopic shift in the ROC group compared with the control group (-0.25 diopter [D]/year vs. -0.38 D/year; P = 0.029). The multivariate analysis demonstrated that the variables of intervention of the ROC program and higher school year proved to be a protective factor against myopia shift in nonmyopic subjects (P = 0.020 and P = 0.017, respectively). For myopic subjects, school year was the only variable significantly associated with myopia progression (P = 0.006). Outdoor activities during class recess in school have a significant effect on myopia onset and myopic shift. Such activities have a prominent effect on the control of myopia shift, especially in nonmyopic children. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Acute onset myopia as a presenting feature of systemic lupus erythematosus

Acute onset myopia as a presenting feature of systemic lupus erythematosus

Full correction and Undercorrection of Myopia Evaluation Trial: design and baseline data of a randomized, controlled, double‐blind trial

To determine the difference in the rate of myopic progression between children wearing single vision lenses with undercorrection of +0.50 D and children whose myopia is fully corrected, and to explore the factors that may influence the process. Randomized, controlled, double-blind trial. Two hundred children aged 7-15 years with low-to-moderate myopia (-1.5 D to -6.0 D), astigmatism <-1.5 D and anisometropia <1.0 D. The children were randomly allocated to wear single vision lenses with full correction or undercorrection by +0.50 D. Ocular examinations and questionnaire surveys for myopia-related factors will be performed every 6 months. Cycloplegic autorefraction and axial length. Of 200 children, 100 (50%) were girls, 41 (21%) esophoric and 82 (42%) exophoric at near. The characteristics of gender, age, age of myopia onset, phoria, eye dominance, parental myopia, refractive error, axial length, corneal curvature, mean time spent in near work and outdoor activities between the two groups were not significantly different. The accommodative responses at 33 cm, the accommodative demands and lags at infinity were significantly different in the two groups as they were measured with full correction in one group and undercorrection in the other. Full correction and Undercorrection of Myopia Evaluation Trial is a clinical trial designed to determine the effectiveness of undercorrection of myopia by +0.5 D on myopic progression in a population of school-aged children known to be susceptible to myopia and to identify the factors influencing the process.

Accommodative response and nearwork-induced transient myopia induced by simplified and traditional Chinese characters

Background Epidemiologic studies found that the incidence of myopia is higher in Hong Kong and Taiwan regions of China than that of the mainland.So whether the general reading words with traditional Chinese characters and simplified characters is associated with myopia deserves attention.Objective This study was to test the accommodative responses and the regression levels of nearwork-induced transient myopia (NITM) induced by traditional complex Chinese characters and modern simplified ones in the same size,and to explore the differences and inherent relationship of the accommodative regulations based on the structures of the two types of Chinese character in causing reading triggered myopia.Methods Twenty two volunteers aged 24-29 years were included in this study with informed consent.The corrected vision of both eyes from each subject was ≥ 1.0 with a mean spherical equivalence of (-1.86±2.34)D.Accommodative response was tested with 4 different reading texts using the rapid sequence visual presenting model with the GRAND SEIKO-WV5500 infrared autorefractor,and this procedure was performed after full correction of refractive error.An initial test of looking at a certain distance was performed (as baseline),and then the subjects read intensively at the targets for 10 minutes at 33 cm to calculate the accommodative responses.After a 10 second pause,the ocular refractive status was obtained exactly at 15 seconds,20 seconds.The one-way ANOVA method was used to determine the effects of the different font types and sizes on the adjustive responses and the causation of NITM.Results Accommodative response induced by simplified and traditional Chinese characters showed an accommodative lag of (1.11 ±0.38),(0.95 ±0.43),(1.18 ±0.33) and (1.06±0.28) D,showing a significant difference among the 9 pt and 12 pt simplified and traditional Chinese characters (F =1.62,P =0.19),and significantly different accommodative lag values between 12 pt simplified characters and 9 pt traditional characters was found (t =5.56,P =0.02).NITM induced by the four different targets were (-0.45 ±0.45),(-0.47 ±0.46),(0.45 ±0.82) and (-0.46±0.78) D in the 4 types of characters,without a significant difference among them (F=0.01,P =0.99).Conclusions Near-distance reading causes accommodative lag regardless of the type of reading texts.The target demonstrated stimuli spatial frequency and font size play an impact on accommodative responses.NITM appears when one reads simplified or traditional Chinese for 10 minutes.The accommodative lag and NITM trend might be responsible for the onset or regression of myopia,yet it is not supportive for the hypothesis that reading traditional Chinese causes more strain since there is no difference between the two. Key words: Myopia; Accommodative response; Nearwork-induced transient myopia; Chinese character/simplified, traditional

The Relationship between Growth Spurts and Myopia in Singapore Children

We aimed to determine the relationship between puberty and growth spurts with peak spherical equivalent (SE) or axial length (AL) velocity in Singapore schoolchildren. In the Singapore Cohort Study of the Risk Factors for Myopia of 1779 schoolchildren, the longitudinal refractive and pubertal status of 892 boys and 887 girls from ages 6 to 14 years were assessed. The study sample included 1329 Chinese, 316 Malays, 114 Indians, and 20 children of other races. Information regarding puberty parameters, age of peak height velocity, age of menarche, and break of voice (BOV) was obtained. Peak velocity was defined as the greatest change in measurements over a period of 1 year. Tanner stage 1 for pubic hair or breast development, in boys and girls, respectively, at age 12 was categorized as "later puberty," whereas stages 2 to 5 corresponded to "earlier puberty." Refractive error was determined by cycloplegic autorefraction using the Canon RK-F5, and AL was measured using the A-scan biometry machine. The children were examined annually, and the mean number of visits was 5.7 ± 1.3. Age of peak height velocity occurred earlier in girls than in boys (11.0 ± 1.2 vs. 12.0 ± 1.7 years, P < 0.001). Girls with earlier peak height velocity experienced peak AL velocity and peak SE velocity approximately half a year earlier than those with later puberty (mean age of 10.3 ± 1.6 vs. 10.8 ± 1.7 years, P < 0.001; and 10.0 ± 1.5 vs. 10.6 ± 1.25 years, P < 0.001, respectively). Similarly, boys who had earlier peak height velocity also achieved peak AL and peak SE velocity earlier than those who experienced later peak height velocity (mean age of 10.4 ± 1.6 vs. 11.1 ± 1.8 years, P < 0.001; and 10.1 ± 1.5 vs. 10.6 ± 1.7 years, P = 0.01). Both girls and boys who had early peak height velocity had earlier age of onset of myopia than those with later peak height velocity (9.7 ± 1.4 vs. 10.1 ± 1.5 years for girls, P = 0.04; and 9.9 ± 1.5 vs. 10.4 ± 1.6 years for boys, P = 0.03). Myopia progression, in terms of AL velocity, also occurred earlier in boys and girls with earlier peak height velocity (10.2 ± 1.5 vs. 11.0 ± 1.9 for boys, P < 0.001; and 10.2 ± 1.5 vs. 10.7 ± 1.7 for girls, P = 0.004, respectively). The associations were not significant when Tanner staging, age of menarche, or BOV was used to determine stage of puberty. Boys and girls with earlier peak height velocity experienced earlier peak SE and AL velocity, and age of myopia onset. Thus, variations in the onset and peak progression of myopia may be associated with height spurts.

Time Outdoors, Visual Activity, and Myopia Progression in Juvenile-Onset Myopes

To investigate the association between myopia progression and time spent outdoors and in various visual activities. Subjects were 835 myopes (both principal meridians -0.75 diopters [D] or more myopia by cycloplegic autorefraction) in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study with both progression data and at least one measure of activity associated with a progression interval. Activity data were collected by parental survey. Average activity level (mean of the activity at the beginning and the end of a 1-year progression interval) was the primary predictor in a repeated-measures mixed model. The model controlled for age, sex, ethnicity, refractive error at the beginning of the progression interval, clinic site, and type of autorefractor used. Effects were scaled based on performing an additional 10 hours per week of an activity. In the multivariate model, the number of hours of reading for pleasure per week was not significantly associated with annual myopia progression at an a priori level of P ≤ 0.01, nor were the other near activities, the near-work composite variable diopter-hours, or outdoor/sports activity. The magnitude of effects was clinically small. For example, the largest multivariate effect was that each additional 10 hours of reading for pleasure per week at the end of a progression interval was associated with an increase in average annual progression by -0.08 D. Despite protective associations previously reported for time outdoors reducing the risk of myopia onset, outdoor/sports activity was not associated with less myopia progression following onset. Near work also had little meaningful effect on the rate of myopia progression.

Changes in Lens Power in Singapore Chinese Children during Refractive Development

To examine changes in lens power during refractive development in Singapore Chinese children. Children aged six to nine years from three Singapore schools were invited to participate in the Singapore Cohort study Of the Risk factors for Myopia (SCORM) study. Cycloplegic refractions and biometry were measured annually in the schools over a five year period from 1999. Children were classified into five refractive error groups: persistent hyperopia, emmetropizing hyperopia, persistent emmetropia, newly developed myopia, or persistent myopia. Crystalline lens power was calculated using Bennett's formula. The rate of change per year across the refractive groups was adjusted for age and sex using General Linear Models. There were 1747 children with at least three sets of measurements for lens power calculations. The mean age at baseline was 7.94 ± 0.84 years and the mean spherical equivalent refraction was -0.41 ± 1.71 diopters (D). Lower lens power and lower lens thickness were associated with persistent myopia. As expected, the newly developed myopes and the persistent myopes showed the largest changes in axial length (AL). Changes in lens power and thickness at follow-up were similar in all refractive groups, except for the newly developed myopes, who showed significantly greater decreases in lens power (0.36 vs. 0.29 D/year; P < 0.001) and lens thickness (0.015 vs. 0.0003 mm/year; P < 0.001) than the persistently emmetropic group. Newly developed myopes showed a significantly greater decrease in lens power than other refractive groups, which may be linked to rapid changes in AL and refraction that occur around the onset of myopia.

Whole globe inflation testing of exogenously crosslinked sclera using genipin and methylglyoxal

Exogenous collagen cross-linking has been investigated as method of reinforcing scleral biomechanics, with the goal of counteracting scleral weakening that occurs at the onset of myopia. This study uses whole globe inflation testing to investigate the biomechanical effect of treating posterior sclera with the collagen cross-linking agents methylglyoxal and genipin. Pairs of porcine eyes were treated in four ways. Three groups involved 1% methylglyoxal: two-hour (Group I) or thirty-minute (Group II) incubation of the whole globe, and thirty-minute incubation of only the posterior sclera of the intact eye (Group III). Group IV consisted of a thirty-minute incubation of the posterior sclera in 1% genipin. Following treatment, each eye was subjected to inflation testing under physiological pressure levels (0–150 mmHg); four strain markers on the posterior pole were tracked, providing displacement measurements in two directions. Results were used to derive load versus deformation behavior and to calculate stiffness at 0.25% strain (toe stiffness) and at peak strain (peak stiffness). Toe stiffness of Group I was 4.8 and 1.3 times greater than controls (sagittal and transverse directions, respectively: 5.23 ± 0.39 vs. 0.90 ± 0.08 mHg, P < 0.001; and 3.41 ± 0.19 vs. 1.51 ± 0.22 mHg, P < 0.01; values in mean ± SE). Group II was 7.4 and 4.3 times stiffer than controls (sagittal and transverse directions, respectively: 5.26 ± 0.49 vs. 0.63 ± 0.10 mHg, P < 0.02; and 3.44 ± 0.44 vs. 0.65 ± 0.07 mHg, P < 0.003). Group III was 3.6 and 3.4 times stiffer than controls (sagittal and transverse directions, respectively: 5.21 ± 0.39 vs. 1.13 ± 0.31 mHg, P < 0.01; and 4.94 ± 1.48 vs. 1.13 ± 0.25, P < 0.01), while Group IV was 8.2 and 2.8 times stiffer than controls (sagittal and transverse: 12.36 ± 1.96 vs. 1.35 ± 0.14 mHg, P < 0.01; and 12.45 ± 1.34 vs. 3.27 ± 0.50 mHg, P < 0.05). In all groups, there was no significant difference in peak stiffness after scleral cross-linking (SXL). At low strain, the posterior sclera was stiffer in both measured directions following methylglyoxal and genipin treatments, however at peak strain the treated sclera was not stiffer. Additionally, the saturation level of scleral stiffening by methylglyoxal can be reached within thirty minutes of treatment.

Macular folds: an unusual association in topiramate toxicity

We report two uncommon cases of acute onset myopia with macular folds following use of topiramate. A 25‐year‐old woman, with no prior history of glasses, taking topiramate for recurrent headaches, presented with decreased vision. On examination, she was found to have a refractive error of ‐5.00-DS in both eyes and intraocular pressure of 10-mmHg and 6-mmHg in the right and left eyes, respectively. She had closed angles on gonioscopy, ciliary effusion on ultrasonic biomicroscopy with inner limiting membrane folds in the macula in both eyes. She was on anti‐glaucoma medication when she presented to us.A 20‐year‐old woman presented with acute headache and decreased vision following use of topiramate for treatment of migraine. On examination, her intraocular pressure was 25-mmHg in both eyes with closed angles on gonioscopy, a refractive error of ‐4.50-DS and prominent macular folds with no fluid in both eyes.There was complete resolution of macular folds and angle‐closure attack after discontinuation of topiramate and conservative treatment with topical steroids and cycloplegics in both eyes.Topiramate toxicity may present with macular folds associated with angle‐closure glaucoma. Folds in the inner limiting membrane might give a clue to choroidal effusion as the cause for this presentation. The symptoms resolved on the discontinuation of topiramate.

Annual Changes in Refractive Errors and Ocular Components before and after the Onset of Myopia in Chinese Children

To examine annual changes in refraction and ocular components around the onset of myopia in Chinese children. Longitudinal study. Twins aged 7 to 15 years in 2006 from the Guangzhou Twin Registry. Participants underwent eye examinations annually from 2006 to 2010. Years were defined (+1 or -1) relative to the examination at which the onset of myopia was first identified. Annual change in spherical equivalent refraction (SER) and ocular biometry. Children who were not myopic at the first examination and myopic in at least 1 subsequent examination from 2006 to 2010 were included in the analysis. Annual change in SER increased slowly from 4 years before the first detection of myopia to 2 years before myopia onset (-0.25 to -0.4 diopter [D]). The rate of progression was the highest during the year of onset (-0.92 D). After the first detection of myopia, the rate of progression decreased to -0.71 D in the following year and kept decreasing. Annual change in axial length showed a similar, but inverse, shape to that of SER. Annual change in lens power did not change significantly around the onset of myopia. Before the onset of myopia, axial elongation and progression accelerate. After a myopic refraction is established, axial elongation and progression decrease. We suggest that the increases before myopia may be due to increased intensity of study and decreased time outdoors. In contrast, the rapid slowing after the onset of myopia may represent an inhibitory effect of myopic defocus on eye growth.