Relative peripheral refraction and its role in myopia onset in teenage students.

To test the hypothesis that relative peripheral hyperopia predicts development and progression of myopia. Refraction along the horizontal visual field was measured under cycloplegia at visual field angles of 0°, ±15°, and ±30° at baseline, 1 and 2 years in over 1700 initially 7-year-old Chinese children, and at baseline and 1 year in over 1000 initially 14-year olds. One refraction classification for central refraction was "nonmyopia, myopia" (nM, M), consisting of nM greater than -0.50 diopters (D; spherical equivalent) and M less than or equal to -0.50 D. A second classification was "hyperopia, emmetropia, low myopia, and moderate/high myopia" (H, E, LM, MM) with H greater than or equal to +1.00 D, E, -0.49 to +0.99 D, LM, -2.99 to -0.50 D, and MM less than or equal to -3.00 D. Subclassifications were made on the basis of development and progression of myopia over the 2 years. Changes in central refraction over time were determined for different groups, and relative peripheral refraction over time was compared between different subgroups. Simple linear regression of central refraction as a function of relative peripheral refraction did not predict myopia progression as relative peripheral refraction became more hyperopic: relative peripheral hyperopia and relative peripheral myopia predicted significant myopia progression for 0% and 35% of group/visual field angle combinations, respectively. Subgroups who developed myopia did not have more initial relative peripheral hyperopia than subgroups who did not develop myopia. Relative peripheral hyperopia does not predict development nor progression of myopia in children. This calls into question the efficacy of treatments that aim to slow progression of myopia in children by "treating" relative peripheral hyperopia.

To determine the peripheral refraction of children with different types of ametropias and to evaluate the relationship between central refractive changes, baseline relative peripheral refraction (RPR) and changes in RPR over a 12-month monitoring period. Cycloplegic central and peripheral refraction were performed biannually on the right eyes of children aged 6-9 for 12 months, using an open-view autorefractor. Peripheral refraction were measured along 10°, 20° and 30° from central fixation in both nasal and temporal fields. Refractive data were transposed into M, J0 and J45 vectors for analyses. RPR was determined by subtracting the central measurement from each peripheral measurement. Hyperopic eyes showed relative peripheral myopia while myopic eyes had relative hyperopia across the central 60° horizontal field at baseline. Emmetropic eyes had relative myopia within but showed relative hyperopia beyond the central 30° field. However, there was no significant correlation between central refractive changes and baseline RPR or between changes in central refraction and RPR over twelve months in any refractive groups. Correlations between changes in PR and central myopic shift were found mainly in the nasal field in different groups. In the subgroup analysis on the initially emmetropic and the initially myopic groups, the subgroups with faster myopic progression did not have significantly different RPR from the subgroups with slower progression. The RPR pattern of the initially emmetropic and the initially myopic groups became more asymmetric at the end of the study period with a larger increase in relative hyperopia in the temporal field. RPR patterns were different among hyperopic, emmetropic and myopic eyes. However, baseline RPR and changes in RPR cannot predict changes in central refraction over time. Our results did not provide evidence to support the hypothesis of RPR as a causative factor for myopic central refractive changes in children.

The investigation of peripheral refraction profiles in Indian myopes showed relative peripheral hyperopic refraction in temporal retina and possible dominant role of hyperopic defocus signals from temporal retina in the development of myopia. Considering that the peripheral refraction profiles were extensively reported to be associated with the central refractive error and vary among different ethnicities, we investigated the peripheral refraction profiles in Indians. A total of 161 participants aged between 18 and 33 years were included in the study. All of the eligible participants underwent a comprehensive eye examination. Central and peripheral refractions were determined using an open-field autorefractor in 10° intervals up to ±30° in the horizontal meridian, and in 5° intervals up to ±15° in the vertical meridian. Axial length and central corneal radius were measured using a non-contact optical biometer. Peripheral refraction was compared between the different refractive error groups and myopic subgroups. Myopes showed a significant asymmetrical peripheral refraction profile along horizontal meridian with relative peripheral myopia at nasal 30° and relative peripheral hyperopia at temporal 30° (mean ± standard error at N30°: -0.37 ± 0.13 D vs. T30°: +0.56 ± 0.11 D, P < .05). Emmetropes and hyperopes showed relative peripheral myopia both in nasal and temporal eccentricities. Relative peripheral refraction was significantly different between the refractive groups and myopic subgroups along the temporal retinal eccentricities only (P < .05). Along the vertical meridian, relative peripheral myopia was seen among the three refractive error groups (P < .05). J0 and J45 significantly changed with retinal eccentricity along both the meridians in all the refractive error groups (P < .05). Myopes showed an asymmetric type of peripheral refraction with relative hyperopic defocus in temporal retina and myopic defocus in the nasal retina. Possible role of retinal hyperopic defocus along temporal retina in myopiogenesis needs to be explored.

The change in refraction caused by accommodation inevitably affects the peripheral defocus state and thus may influence the effect of retinal peripheral myopic defocus measures in myopia control. This study investigated accommodation changes in different peripheral retinas under cycloplegia to help improve myopia control. Fifty-six eyes of fifty-six myopic subjects were recruited for this prospective study. The center and peripheral retina refractions were measured using multispectral refractive topography. The subjects were divided into low-to-moderate myopia group (range: -1.25 D to -6.00 D) and high myopia group (range: -6.25 D to -9.75 D) according to spherical equivalent (SE). The compound tropicamide (0.5% tropicamide and 0.5% phenylephrine) was used to relax the accommodation. The difference between cycloplegia and non-cycloplegia peripheral retinal refraction was analyzed using the t-test. The correlation between eccentricity and changes in peripheral refraction was analyzed using Pearson's correlation analysis. The manifest refraction of the retina significantly decreased with an increase in eccentricity after cycloplegia. The annular refraction difference value at 50°-53° (ARDV 50-53) showed the largest refraction decrease of 1.31 D compared with the central retinal refraction decrease of 0.84 D. The inferior quadrantal refraction difference value had the least change compared to the other quadrants. The relative peripheral refraction (RPR) changes in refraction difference value (RDV) at 15° (RDV-15), RDV-30, and RDV-45 were less than 0.15 D. When the range of annulus narrowed to 5°, the narrower annulus showed faster change with eccentricity increase in ARDV 30-35, ARDV 35-40, ARDV 40-45, ARDV 45-50, and ARDV 50-53. The RPR was highly correlated with eccentricity (R = 0.938 and P < 0.001). The high myopia group had a greater hyperopic shift in the periphery than the low-to-moderate group after cycloplegia. Peripheral refraction showed a significant hyperopic shift after cycloplegia with an increase in eccentricity. The RPR became more hyperopic than the central refraction. The high myopia group showed more hyperopic shifts in the peripheral region. Accommodation should be taken into consideration in peripheral defocus treatment.

Optical solutions that create peripheral myopic defocus in the presence of a clear central image have shown to be effective as myopia treatment. This study investigates whether peripheral refraction measured via MRI and ray tracing can predict myopia progression in children. A total of 1635 children from the Generation R Study, a population-based birth cohort in Rotterdam, the Netherlands, underwent T2 weighted MRI scanning at age 9 years. At both ages 9 and 14 years, ocular biometry, and cycloplegic autorefraction were assessed. Retinal curvature radii were computed from MRI segmentations using semi-automated, customized image processing algorithms. Individual peripheral refraction profiles were modelled through ray tracing. Horizontal and vertical peripheral refraction was analysed at 50-degrees eccentricity. Relative peripheral refraction (RPR) was calculated by subtracting peripheral refraction from central cycloplegic refraction. Yearly myopia progression was calculated and stratified into quantiles (∆AL), and the effect of RPR on the quantile outcomes was examined using ordinal regression analyses. Predictive performance of RPR on development of myopia was evaluated using ROC-analysis (fast vs slow progressors) and a logistic regression (incident myopia). At age 9 years, 207/1635 (13%) children had developed myopia. Myopic children had a significantly more hyperopic RPR compared to emmetropic children at all horizontal eccentricities (-1.8 ± 1.8D vs. 0.2 ± 2.1D) and vertical eccentricities (-1.0 ± 1.9D vs. 0.8 ± 2.2D). Higher vertical (OR: 1.08, CI: 1.02-1.14) and horizontal RPR (OR: 1.16, CI: 1.10-1.22) was associated with faster AL progression. Each diopter increase in vertical RPR (OR: 1.10, CI: 1.01-1.20) and horizontal RPR (OR: 1.23, CI: 1.13-1.35) was associated with an increased risk of incident myopia. ROC analysis indicated that RPR had a maximum predictive AUC of 0.77 for identifying fast progressors. Furthermore, MRI data revealed significant interindividual variations in retinal curvature (SD 1 mm), which resulted in clinically relevant peripheral refractive differences exceeding 8D among children with similar axial length and central SE, suggesting that standard defocus strategies may require individualization. Using this novel approach to calculate peripheral refraction, we provide evidence based on eye shape that peripheral hyperopic refractive error is more pronounced in myopic children and is strongly associated with myopia progression. The significant anatomical variability in retinal radii underscores the need for personalized treatment strategies, which may enhance the efficacy of optical interventions for myopia management.

BackgroundTo determine the peripheral refraction characteristics related to 18-month changes in refraction in Caucasian (Mediterranean) children.MethodsNon-cycloplegic peripheral refraction at 10° intervals over the central ±30° of horizontal visual field over 18 months (baseline, 12 months, and 18 months of follow-up) was conducted in 50 healthy children who were 8 years old. Axial length (AL) was also recorded. Relative peripheral refraction (RPR) was calculated and eyes were divided into three study groups: non-myopic eyes, myopic eyes, and eyes that develop myopia.ResultsMyopic eyes showed hyperopic RPR and emetropic and hyperopic eyes showed myopic RPR. Univariate analysis of variance did not find any statistically significant effect of peripheral refraction (F36=0.13; P=1.00) and RPR (F36=0.79; P=0.80) on myopia onset (eyes that developed myopia along the study). All the studied groups showed an increase of AL, without statistically significant differences between the studied groups (F6=0.09; P=0.99).ConclusionHyperopic relative peripheral shift change in eyes that develop myopia has been found with differences in RPR between myopic (hyperopic RPR) and hyperopic or emmetropic eyes (with myopic RPR). The results suggest that RPR cannot predict development or progression of myopia in Caucasian (Mediterranean) children and the efficacy in slowing myopia progression obtained with treatments that manipulate the peripheral refraction is not just driven with RPR.

Peripheral refraction is believed to be involved in the development of myopia. The aim of this study was to compare the relative peripheral refraction (RPR) at four different levels of illuminance, ranging from photopic conditions to complete darkness, using an open-field autorefraction method. The RPRwas calculated for each eccentricity by subtracting central from peripheral autorefraction measurements. The study included 114 myopic eyes from 114 subjects (mean age of 21.81 ± 1.91 years) and the mean difference in RPRbetween scotopic and photopic conditions (0 and 300 lux, respectively) was +0.32 D at 30° temporal and +0.37 D at 30° in the nasal visual field (NVF). Statistically significant differences were observed between 0 and 300 lux at 30° in the temporal visual field and at 30° and 20° in the NVF. Our results revealed a significant increase in relative peripheral hyperopia with increasing visual field eccentricity along the horizontal visual field in myopic eyes of young adults. Furthermore, this relative peripheral hyperopia increased as illumination decreased. These findings suggest that an increase in peripheral illuminance may protect against myopic eye growth.

On average, myopic eyes present a relative hyperopia in the peripheral retina. This has been associated with the possibility that by modifying the peripheral refraction, the progression of central myopia could be controlled. The authors explored how refractive errors and optical aberrations interact in the formation of the retinal image in the periphery, in eyes with different central refractions. The authors used a fast and high-angular resolution scanning wavefront sensor to measure the optical image quality of the eye in the horizontal meridian (± 40°) in 202 eyes of 101 subjects, 54 males and 47 females with an average age (std) of 27.5 (± 7.2) years and an average foveal refraction (std) of -0.8 (± 1.3 D) of which 64 were non-myopes (refraction ± std: 0.01 ± 0.46 D) and 37 myopes (-2.12 ± 1.08 D). They evaluated the relationship between peripheral optical properties and central refraction using different metrics. The authors observed a significant tendency to a relative hyperopia in the periphery of the myopic eyes. The relative peripheral refraction (RPR) was significantly different between the emmetropic and myopic eyes from 15°-40° temporal retina and from 20°-40° nasal retina. The mean RPR metric correlated with the central refraction of the subject (r = -0.552 / -0.560 [OD / OS]). The image quality presented only minor differences between the various refractive groups at angles of 30°-40° when the central refraction was corrected. Peripheral overall blur is mostly influenced by the interaction of defocus and oblique astigmatism, and at larger eccentricities is similar for the different refractive groups. This could argue against the hypothesis that a relative peripheral hyperopia could drive eyes toward myopia.

The aim of this study was to determine the relationship between relative peripheral refraction and retinal shape by 2-D magnetic resonance imaging in high myopes. Thirty-five young adults aged 20 to 30 years participated in this study with 16 high myopes (spherical equivalent < −6.00 D) and 19 emmetropes (+0.50 to −0.50 D). An open field autorefractor was used to measure refractions from the center out to 60° in the horizontal meridian and out to around 20° in the vertical meridian, with a step of 3 degrees. Axial length was measured by using A-scan ultrasonography. In addition, images of axial, sagittal, and tangential sections were obtained using 2-D magnetic resonance imaging. The highly myopic group had a significantly relative peripheral hyperopic refraction and showed a prolate ocular shape compared to the emmetropic group. The highly myopic group had relative peripheral hyperopic refraction and showed a prolate ocular form. Significant differences in the ratios of height/axial (1.01 ± 0.02 vs. 0.94 ± 0.03) and width/axial (0.99 ± 0.17 vs. 0.93 ± 0.04) were found from the MRI images between the emmetropic and the highly myopic eyes (p < 0.001). There was a negative correlation between the retina’s curvature and relative peripheral refraction for both temporal (Pearson r = −0.459; p < 0.01) and nasal (Pearson r = −0.277; p = 0.011) retina. For the highly myopic eyes, the amount of peripheral hyperopic defocus is correlated to its ocular shape deformation. This could be the first study investigating the relationship between peripheral refraction and ocular dimension in high myopes, and it is hoped to provide useful knowledge of how the development of myopia changes human eye shape.

Considering the potential role of the peripheral retina in refractive development and giventhat peripheral refraction varies significantly with increasing eccentricity from the fovea, we investigated the association between relative peripheral refraction (RPR) and corresponding relative peripheral multifocal electroretinogram (mfERG) responses (electro-retinal signals) from the central to the peripheral retina in young adults. Central and peripheral refraction using an open-field autorefractor and mfERG responses using an electrophysiology stimulator were recorded from the right eyes of 17 non-myopes and 24 myopes aged 20-27 years. The relative mfERG N1, P1 and N2 components (amplitude density and implicit time) of a mfERG waveform were compared with the corresponding RPR measurements at the best-matched eccentricities along the principal meridians, that isatthe fovea (0°), horizontal (±5°, ±10° and ± 25°) and vertical meridians (±10° and ± 15°). The mean absolute mfERG N1, P1 and N2 amplitude densities (nV/deg2 ) were maximum at the fovea in both non-myopes (N1: 57.29 ± 14.70 nV/deg2 , P1: 106.29 ± 24.46 nV/deg2 , N2: 116.41 ± 27.96 nV/deg2 ) and myopes (N1: 56.25 ± 15.79 nV/deg2 , P1: 100.79 ± 30.81 nV/deg2 , N2: 105.75 ± 37.91 nV/deg2 ), which significantly reduced with increasing retinal eccentricity (p < 0.01). No significant association was reported between the RPR and corresponding relative mfERG amplitudes at each retinal eccentricity (overall Pearson's correlation, r=-0.25 to 0.26, p ≥ 0.09). In addition, the presence of relative peripheral myopia or hyperopia at extreme peripheral retinal eccentricities did not differentially influence the corresponding relative peripheral mfERG amplitudes (p ≥ 0.24). Relative peripheral mfERG signals are not associated with corresponding RPR in young adults. It is plausible that the electro-retinal signals may respond to the presence of absolute hyperopia (and not relative peripheral hyperopia), which requires further investigation.

Background The relationship between the relative peripheral refraction (RPR) of retina and the development of myopia has recently become the concerns for researchers.However, there have been few data on the RPR and the astigmatic vector patterns in myopic populations.It is needed to study the RPR and the astigmatic vector patterns in the Chinese young myopic subjects. Objective The RPR and astigmatic vector patterns were determined in Chinese young myopic subjects. Methods This prospective study comprised 301 Chinese young myopic subjects who visited ophthalmology department of Peking University People's Hospital from June 2014 to October 2015.Horizontal peripheral refractions were measured in 5° steps out to 30° eccentricity in both the nasal and temporal visual fields using Grand Seiko WAM-5500 autorefractor.Only data from the right eyes were used for analyses.Spherical equivalent refractions (SER) at each angular position were calculated and the relative peripheral refractive errors (expressed as defocus) were determined by subtracting the peripheral SER from the central SER.The RPR was categorized based on the shapes of peripheral refractive curves and the relative positions in the nasal or temporal retinal regions.Astigmatism at each angle was decomposed into J0 and J45 vectors based on Fourier decomposition and the curve patterns for the astigmatic vectors were examined.This study adhered to the tenets of the Declaration of Helsinki and was approved by the Human Research Ethics Committee of Peking University People's Hospital. Results Seven types of relative peripheral refractive curves were identified (retinal regions)∶ negative defocus, temporal positive defocus and nasal flatness, temporal positive and nasal negative defocus, temporal flatness and nasal negative defocus, flatness in both temporal and nasal retina, temporal negative defocus and nasal flatness, and positive defocus.Patterns of astigmatic vector J0 and J45 were divided into 9 categories.The rate of type Ⅰ RPR was significantly greater in the moderate and high myopia group than that in the low myopia group (χ2=26.770, P<0.05). The rate of type Ⅲ was significantly greater in the low myopia group than that in the moderate and high myopia group (χ2=12.500, P<0.05). Conclusions The distributions of RPR were significantly different between low myopia group and moderate and high myopia group.There were nasal-temporal asymmetries for the absolute values of astigmatism along peripheral horizontal meridian.The absolute values of astigmatism in the nasal retinal regions were increased with the increase of fixation angles (except for the value at nasal 10°). Key words: Relative peripheral refraction; Myopia; Peripheral defocus

PurposeRefraction in the peripheral visual field is believed to play an important role in the development of myopia. The purpose of this study was to investigate the differences in peripheral refraction among anisomyopia, isomyopia, and isoemmetropia for schoolchildren.MethodsThirty-eight anisomyopic children were recruited and divided into two groups: (1) both eyes were myopic (anisomyopic group, AM group) and (2) one eye was myopic and the contralateral eye was emmetropic (emmetropic anisomyopic group, EAM group). As controls, 45 isomyopic and isoemmetropic children were also recruited with age and central spherical equivalent (SE) matched to those of the AM and EAM groups. The controls were divided into three groups: (1) intermediate myopia group (SE matched to the more myopic eye of AM group), (2) low myopia group (SE matched to the less myopic eye of AM group and the more myopic eye of EAM group), and (3) emmetropia group (SE matched to the less myopic eye of EAM group). Peripheral refraction at 7 points across the central ±30° on the horizontal visual field with a 10° interval was measured with an autorefractor. Axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were also determined by using the Zeiss IOL-Master.ResultsThe relative peripheral spherical equivalent [RPR(M)] and relative peripheral spherical value [RPR(S)] of the more myopic eye was shifted more hyperopically than the contralateral eye in both the AM and the EAM groups (both p<0.0001). The RPR(M, S) of the less myopic eyes in the AM and EAM groups showed a relatively flat trend across the visual field and were not significantly different from the emmetropia group. The RPR(M, S) of less myopic eyes in the AM group were shifted less hyperopically than in the isomyopic low myopia group and the more myopic eye of the EAM group [RPR(M), p = 0.007; RPR(S), p = 0.001], although the central SEs of the three groups were not significantly different from each other. However, RPR(M, S) of the more myopic eyes were not different from the corresponding isomyopic groups. There was also no significant difference in the relative peripheral astigmatism [RPR(J0, J45)] between the more and the less myopic eyes in either the AM or the EAM group.ConclusionRefraction of anisomyopia differs between the two eyes not only at the central visual field but also at the off-axis periphery. The relative peripheral refraction of the more myopic eye of anisomyopia was shifted hyperopically, as occurs in isomyopia with similar central subjective SE values. Less myopic eyes were much less hyperopically shifted in relative peripheral refraction than the corresponding isomyopic eyes, but are comparable to emmetropic eyes. This emmetropia-like relative peripheral refraction in less myopic eyes might be a factor responsible for slowing down the progression of myopia.

To investigate changes in peripheral refraction with under-, full, and over-correction of central refraction with commercially available single vision soft contact lenses (SCLs) in young myopic adults. Thirty-four myopic adult subjects were fitted with Proclear Sphere SCLs to under-correct (+0.75 DS), fully correct, and over-correct (-0.75 DS) their manifest central refractive error. Central and peripheral refraction were measured with no lens wear and subsequently with different levels of SCL central refractive error correction. The uncorrected refractive error was myopic at all locations along the horizontal meridian. Peripheral refraction was relatively hyperopic compared to center at 30 and 35° in the temporal visual field (VF) in low myopes and at 30 and 35° in the temporal VF and 10, 30, and 35° in the nasal VF in moderate myopes. All levels of SCL correction caused a hyperopic shift in refraction at all locations in the horizontal VF. The smallest hyperopic shift was demonstrated with under-correction followed by full correction and then by over-correction of central refractive error. An increase in relative peripheral hyperopia was measured with full correction SCLs compared with no correction in both low and moderate myopes. However, no difference in relative peripheral refraction profiles were found between under-, full, and over-correction. Under-, full, and over-correction of central refractive error with single vision SCLs caused a hyperopic shift in both central and peripheral refraction at all positions in the horizontal meridian. All levels of SCL correction caused the peripheral retina, which initially experienced absolute myopic defocus at baseline with no correction, to experience absolute hyperopic defocus. This peripheral hyperopia may be a possible cause of myopia progression reported with different types and levels of myopia correction.

Analysis of the peripheral refraction in myopic adults using a novel multispectral refraction topography

To observe the changes in peripheral refraction in myopic adolescents after overnight orthokeratology and its influencing factors. This was a prospective study among young myopic adolescents aged 8-14 years (n = 21). The peripheral refraction of the subjects was measured at 5, 10, 15, 20, 25, and 30° from the nasal and temporal side to the central fixation by WAM-5500 Open-field refractometer. The axial length, baseline spherical equivalent refraction, and other parameters were measured. The data were measured at baseline and 1, 3, and 12 months after wearing orthokeratology lenses. The relative peripheral refraction at the nasal and temporal side from central to 30° eccentricity revealed relative hyperopic defocus in all subjects at baseline measurement. One month after wearing the orthokeratology lenses, the relative peripheral refraction changed to myopic defocus, the nasal-temporal relative peripheral refraction was asymmetric, and the observed difference was statistically significant. Positive correlations were found between the change amount of nasal relative peripheral refraction and baseline spherical equivalent refraction, the baseline nasal relative peripheral refraction was higher than that on the temporal side, and after orthokeratology, the value of nasal relative peripheral refraction was lower than that on the temporal side. The changes at 30° on both sides were correlated to the axial elongation (rNasal = 0.565, rTemporal = 0.526, p < 0.05). This study demonstrated that after orthokeratology, relative peripheral hyperopia in the myopic patients turned into relative peripheral myopia, and the nasal-temporal asymmetry changed significantly after orthokeratology, which was correlated with the baseline refractive state.