Relative Peripheral Refraction Research Articles

Relative peripheral refraction in myopic children wearing orthokeratology lenses using a novel multispectral refraction topographer

ABSTRACT Clinical relevance Orthokeratology (OK) lens is commonly used to control myopia progression of children. Understanding the relationship between relative peripheral refraction (RPR) and the growth rate of axial length (AL) may assist in explaining myopic progression. Background The aim of this work is to investigate the RPR in myopic children wearing OK lenses, and to evaluate its relationship with the growth rate of AL. Methods RPRs of 31 children wearing OK lenses and 31 children wearing single-vision glasses were measured with multispectral refraction topography (MRT). MRT shows the total RPR (TRPR), RPR in the superior area (RPR-S), RPR in the inferior area (RPR-I), RPR in the temporal area (RPR-T) and RPR in the nasal area (RPR-N), respectively. It also shows RPR in the visual field of 15° (RPR-15), 30° (RPR-30) and 45° (RPR-45), respectively. RPRs in the visual field from 15° to 30°, 30° to 45° and 15° to 45° are recorded as RPR-(30–15), RPR-(45–30) and RPR-(45–15), respectively. According to the growth rate of AL, children wearing OK lenses were further divided into slow and fast growth groups. Results TRPR, RPR-I, RPR-T, RPR-N, RPR-15, RPR-30, RPR-45, RPR-(30–15), RPR-(45–30), and RPR-(45–15) of children in the OK lens group were significantly smaller than in the control group (all P < 0.05). TRPR, RPR-N, RPR-15, RPR-30, RPR-45, RPR-(30–15), and RPR-(45–15) of the slow growth group were significantly smaller than in the fast growth group (all P < 0.05). The growth rate of AL were positively correlated with TRPR (R = 0.383, P = 0.040), RPR-N (R = 0.395, P = 0.034), RPR-30 (R = 0.408, P = 0.028), RPR-45 (R = 0.377, P = 0.044), RPR-(30–15) (R = 0.390, P = 0.036). Conclusions RPRs of children show relative myopic defocus after wearing OK lenses. Furthermore, the growth rate of AL is smaller with more negative RPR.

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

To characterize peripheral refraction and its relationship with myopia development in a selected group of male teenage Chinese students. This 2-year prospective cohort study randomly enrolled 85 non-myopic boys (age, 14-16y) from the Experimental Class of Air Force in China. Cycloplegic peripheral refraction was examined at 0°, ±10°, and ±20° along the horizontal visual field in the right eye at the baseline and 2-year follow-up. The incidence of myopia at the 2-year follow-up was 15.29% (13/85). The baseline central refraction (CR) and peripheral refraction at ±10° were significantly lower in students who developed myopia than in those who did not (P<0.05). Relative peripheral refraction (RPR) did not differ between students with and without myopia (P>0.05). At the 2-year follow-up, the RPR at ±10° and 20° nasal was significantly more hyperopic in the myopic group than in the non-myopic group. Multiple linear regression analysis indicated that the change in CR was significantly correlated with the changes in RPR at 20° nasal, 10° nasal, and 20° temporal. Multivariate Logistic regression analysis indicated that the baseline CR [odds ratio (OR): 0.092, 95% confidence interval (CI): 0.012-0.688, P=0.020] and the baseline RPR at 10° nasal (OR: 0.182, 95%CI: 0.042-0.799, P=0.024) were significantly correlated with incident myopia (Omnibus test, χ 2=10.20, P=0.006). CR change is significantly correlated with changes in RPR, and students who develop myopia have more relative peripheral hyperopia. More baseline CR and relative peripheral hyperopia at 10° nasal are protective of myopia onset.

Myopia Control Effect Is Influenced by Baseline Relative Peripheral Refraction in Children Wearing Defocus Incorporated Multiple Segments (DIMS) Spectacle Lenses.

The aim of this study is to investigate if baseline relative peripheral refraction (RPR) influences the myopia control effects in Chinese myopic children wearing Defocus Incorporated Multiple Segments (DIMS) lenses. Peripheral refraction at 10°, 20°, and 30° nasal (10 N, 20 N, 30 N) and temporal (10 T, 20 T, 30 T) retina were measured at six-month intervals for children who participated in a 2-year randomized controlled trial. The relationship between the baseline peripheral refractions and myopia progression and axial length changes were analysed. A total of 79 children and 81 children in the DIMS and single vision (SV) group were investigated, respectively. In the DIMS group, more baseline myopic RPR spherical equivalent (SE) was associated with more myopic progression (10 N: r = 0.36, p = 0.001; 20 N: r = 0.35, p = 0.001) and greater axial elongation (10 N: r = −0.34, p = 0.001; 20 N: r = −0.29, p = 0.006) after adjusting for co-factors. In the SV group, baseline RPR had association with only myopia progression (10 N: r = 0.37, p = 0.001; 20 N: r = 0.36, p = 0.001; 30 N: r = 0.35, p = 0.002) but not with axial elongation after Bonferroni correction (p > 0.008). No statistically significant relationship was found between temporal retina and myopia progression or axial elongation in both groups. Children with baseline myopic RPR had statistically significant more myopia progression (mean difference around −0.40 D) and more axial elongation (mean difference 0.15 mm) when compared with the children having baseline hyperopic RPR in the DIMS group but not in the SV group. In conclusion, the baseline RPR profile may not influence future myopia progression or axial elongation for the SV lens wearers. However, DIMS lenses slowed down myopia progression and was better in myopia control for the children with baseline hyperopic RPR than the children with myopic RPR. This may partially explain why myopia control effects vary among myopic children. Customised myopic defocus for individuals may optimise myopia control effects, and further research to determine the optimal dosage, with consideration of peripheral retinal profile, is warranted.

Foveal and peripheral visual quality and accommodation with multifocal contact lenses.

Multifocal contact lenses are increasingly popular interventions for controlling myopia. This study presents the short-term effects of multifocal contact lenses on foveal and peripheral vision. The MiSight contact lenses designed to inhibit myopia progression and the 1-Day Acuvue Moist contact lenses designed for presbyopia were investigated. The MiSight produced similar foveal results to spectacles despite the increased astigmatism and coma. The MiSight also reduced the low-contrast resolution acuity in the periphery, despite no clear change in relative peripheral refraction. When compared with spectacles, Acuvue Moist decreased accommodative response and reduced foveal high- and low-contrast resolution acuity, whereas peripheral thresholds were more similar to those of spectacles. The most likely treatment property for myopia control by the MiSight is the contrast reduction in the peripheral visual field and the changed accommodation.

Comparative Study of Relative Peripheral Refraction in Children With Different Degrees of Myopia.

PurposeTo investigate the difference in the retinal refraction difference value (RDV) using multispectral refractive topography (MRT).MethodsNinety myopic participants, who met the enrolment requirements, were examined with an automatic optometer after mydriasis. According to the value of the spherical equivalent (SE), the participants were divided into Emmetropia group (E, +0.5D < SE < −0.5D), Low Myopia (LM, −0.5D < SE ≤ −3D), and Moderate and high Myopia (MM, −3D < SE ≤ −10D). The ocular biological parameters were detected by optical biometrics (Lenstar 900, Switzerland), including axial length (AL), lens thickness (LT), and keratometry (K1, K2). Furthermore, the MRT was used to measure the retinal RDV at three concentric areas, with 15-degree intervals from fovea into 45 degrees (RDV-15, RDV 15–30, and RDV 30–45), and four sectors, including RDV-S (RDV-Superior), RDV-I (RDV-Inferior), RDV-T (RDV-Temporal), and RDV-N (RDV-Nasal).ResultsIn the range of RDV-15, there was a significant difference in the value of RDV-15 between Group E (−0.007 ± 0.148) vs. Group LM (−0.212 ± 0.399), and Group E vs. Group MM (0.019 ± 0.106) (P < 0.05); In the range of RDV 15–30, there was a significant difference in the value of RDV 15–30 between Group E (0.114 ± 0.219) vs. Group LM (−0.106 ± 0.332), and Group LM vs. Group MM (0.177 ± 0.209; P < 0.05); In the range of RDV 30–45, there was a significant difference in the value of RDV 30–45 between Group E (0.366 ± 0.339) vs. Group LM (0.461 ± 0.304), and Group E vs. Group MM (0.845 ± 0.415; P < 0.05); In the RDV-S position, there was a significant difference in the value of RDV-S between Group LM (−0.038 ± 0.636) and Group MM (0.526 ± 0.540) (P < 0.05); In the RDV-I position, there was a significant difference in the value of RDV-I between Group E (0.276 ± 0.530) vs. Group LM (0.594 ± 0.513), and Group E vs. Group MM (0.679 ± 0.589; P < 0.05). In the RDV-T position, there was no significant difference in the value of RDV-T among the three groups. In the RDV-N position, there was a significant difference in the value of RDV-N between Group E (0.352 ± 0.623) vs. Group LM (0.464 ± 0.724), and Group E vs. Group MM (1.078 ± 0.627; P < 0.05). The RDV analysis in all directions among the three groups showed a significant difference between RDV-S and RDV-I in Group LM (P < 0.05). Moreover, the correlation analysis showed that SE negatively correlated with AL, RDV 30–45, RDV-S, RDV-I, and RDV-N.ConclusionsIn this study, there was a significant difference in the value of RDV among Group E, Group LM, and Group MM, and the value of RDV in Group MM was the highest on the whole. In the range of RDV 30–45, there was a growing trend with the increase in the degree of myopia among the three groups. Furthermore, the SE negatively correlated with AL, RDV 30–45, RDV-S, RDV-I, and RDV-N.

Asymmetric Peripheral Refraction Profile in Myopes along the Horizontal Meridian.

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.

Comparison of peripheral refraction and higher-order aberrations between orthokeratology and multifocal soft contact lens designed with highly addition

PurposeTo compare peripheral defocus, higher-order aberrations (HOAs), and contrast visual acuity (CVA) in myopic children wearing orthokeratology (OK) lenses and multifocal soft contact lenses (MSCLs) designed with highly addition.MethodsThis is a prospective, nonrandomized, controlled study. Subjects at 8 to 13 years of age with spherical equivalent refraction from − 1.00 to − 5.00 dioptres (D) were included in the OK group (n = 30) and MSCL group (n = 23). Relative peripheral corneal defocus (RPCD) and relative peripheral refraction (RPR) were measured before and after wearing lenses. HOAs including spherical aberration (SA), coma, trefoil, and total HOAs, and high (100%) and low (10%) CVA were compared between the groups. Axial length (AL) was measured before and after wearing the lenses for 1 year.ResultsAfter wearing the lenses, subjects in the MSCL group had RPCD and RPR values similar to the OK group at the paracentral (within 2 mm of the cornea or 20° of the retina, all p > 0.05) but larger than the OK group at the periphery (all p < 0.05). All HOAs increased after wearing the lenses except the trefoil in the MSCL group (all p < 0.05). HOAs increased more in the OK group (all p < 0.05). The 100% and 10% CVAs were worse in the MSCL group (p = 0.02 and p = 0.004). After 1 year, AL elongation was 0.37 mm (SD = 0.16) in the MSCL group and 0.28 mm (0.16) in the OK group (p = 0.06).ConclusionMSCL produced larger myopic defocus at the periphery, increased less HOAs and had worse CVA than OK lens. The high addition of this MSCL did not result in better myopia control efficacyTrial registrationChinese Clinical Trial Registry: ChiCTR1800018564. Registered 25 September 2018; retrospectively registered, http://www.chictr.org.cn/showproj.aspx?proj=31376

Relative peripheral refraction characteristics and their relationship with retinal microvasculature in young adults: Using a novel quantitative approach

AimTo analyze relative peripheral refraction (RPR) characteristics in young adults and to investigate the relationship between RPR and retinal microvasculature using multispectral refractive tomography (MRT), a novel quantitative approach. MethodsThis cross-sectional study included 278 eyes of 139 young adults. All eyes underwent complete ophthalmic examinations, including MRT, optical coherence tomography angiography (OCTA) and other ocular examinations. Refraction difference values (RDVs) among different rings/sectors were compared using one-way ANOVA in bilateral eyes. Stepwise multiple linear regression analyses were performed between ∆RDV in different rings and ∆density/thickness value in OCTA. ResultsAmong the different rings, the 30°-45°/45°-53° RDV was significantly greater than the inner rings in both eyes. Among the different sectors, RDV in the superior sector was most significantly reduced among all sectors, and RDV in the nasal sector was significantly greater than that in the temporal sector. In the stepwise multiple linear regression analyses, ∆RDV was negatively correlated with ∆radial peripapillary capillary plexus density and ∆macular thickness. ConclusionsMRT may be a useful tool in RPR quantitative assessment. RPR and some OCTA indexes might be closely correlated. Further research should be conducted to investigate the relationships among these indexes in young adults.

Extrinsic and Intrinsic Factors Regulating Juvenile Refractive Development and Eye Growth.

PurposePeripheral refraction and accommodation are intrinsic factors that were once hypothesized to trigger myopia but are now controversial. Previously, home nearwork environment (i.e., extrinsic factor) was reported to be associated with myopia progression. In this study, we aimed to evaluate the potential interaction between extrinsic and intrinsic factors with juvenile refractive development.MethodsNearwork environmental parameters were measured for 50 children (aged 9.3 ± 1.2 years), including net amount and dispersion of defocus. Refraction was measured at near distances and in central field (±30° horizontal) at 3m. The relative peripheral refraction (RPRE) was obtained and presented in a vectoral approach. The linear regression coefficient was extracted (mAcc) from the accommodative stimulus–response curve. RPRE was quadratically regressed against field eccentricity, and the first coefficients (aM, aJ0, aP90, and aP180) were extracted. Relationships between RPRE, baseline accommodation, and 1-year myopia progression (∆M), controlled for the nearwork environment, were evaluated.ResultsCoefficients of RPRE were independent of ∆M. However, additional nearwork environmental parameters significantly improved the variance in ∆M explained by aM and aP180 (P < 0.03). The relationship between intrinsic factor and ∆M was stronger when the extrinsic risk was low (P ≤ 0.01), whereas the relationship was abolished when extrinsic risk was high. For mAcc, it also significantly improved the variance in ∆M explained by nearwork environmental parameters.ConclusionsThe interaction between extrinsic (environment) and intrinsic (RPRE and accommodation) factors is speculated to contribute to juvenile myopia progression. Our findings may also explain the inconsistencies of such intrinsic factors in the literature.

Orthokeratology reshapes eyes to be less prolate and more symmetric

PurposeThis prospective study assessed the influence of wearing and then discontinuing orthokeratology (OK) lenses on retinal shape and peripheral refraction in myopic children. MethodsFifty-eight myopic children (age 8–12 years) were equally divided into an OK group and a single vision spectacles (SVS) group. After 12 months of OK, it was discontinued for 1 month. Peripheral eye length (PEL), relative peripheral refraction (RPR), and corneal parameters were measured in the right eye on the nasal and temporal retinal sides at baseline, 6 months, and 12 months (13 months in OK group) visits. ResultsIn the SVS group, faster elongation of the temporal side PEL made the eyes more asymmetric and prolate, developing a temporal pointed shape. In the OK group, the nasal retinal side PEL grew faster, the nasal RPR developed less hyperopic defocus, and the eye shape became more symmetric and less prolate. The central cornea became thinner and flattened, while the peripheral cornea became steeper. Changes in corneal thickness, relative peripheral corneal power, and K-values were no significant differences for the OK and SVS groups at 12 months. ConclusionsThe cornea reverted to be no difference with myopic children with SVS after 1 month discontinuation of OK. The retinal shape of SVS eyes became more asymmetric and prolate with myopia progression. OK remodelled retinal shape to be less asymmetric and less prolate.

Alterations in peripheral refraction with spectacles, soft contact lenses and orthokeratology during near viewing: implications for myopia control

ABSTRACT Clinical relevance The peripheral refraction profile in myopes with different corrective modalities varies significantly for both distance and near viewing and will have implications in managing myopia. Background This study investigated how the magnitude of peripheral myopic defocus induced by Ortho-K varies with and without accommodation, and how this compares to single vision spectacles and soft-contact-lenses (SCL). Methods Relative peripheral refraction (RPR) of 18 young adults (spherical equivalent −1.00 D to −4.50 D) was determined along the horizontal meridian (±10°, ±20°, ±25°) during distance (3-metres) and near viewing (0.2-metres), and along vertical meridian (±10°, ±15°) for distance viewing alone. Measurements were obtained in an uncorrected state and with single vision spectacles, soft contact lens and Ortho-K. Changes in RPR and astigmatic components were compared between distance and near viewing with all different modalities. Results A significant interaction (p = 0.02) between relative peripheral refraction and the target distance (distance and near viewing) was found among different refractive modalities. Single overnight Ortho-K lens wear alone led to relative peripheral myopia for both distance (mean RPR ± SE: −0.92 ± 0.21D and −1.04 ± 0.22D) and near viewing (−0.71 ± 0.17D and −0.76 ± 0.20D). Comparisons of relative peripheral refraction between different corrective modalities at each eccentricity indicated statistical significance of RPR at extreme locations along both temporal and nasal meridian (±20 and ±25°, p < 0.05). RPR with soft contact lenses and spectacles were similar for both distance and near viewing (p > 0.05). Conclusion Single overnight Ortho-K lens wear alone shifted the RPR in the myopic direction for both distance and near viewing in comparison with single vision spectacles and soft contact lenses. The Ortho-K lens designs that offer a large amount of mid-peripheral corneal steeping, in-turn leading to high relative peripheral myopia for both distance and near viewing and might offer beneficial effects on myopia control.

The Correlations between Horizontal and Vertical Peripheral Refractions and Human Eye Shape Using Magnetic Resonance Imaging in Highly Myopic Eyes.

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.

Manipulation of Front-Surface Profile of Scleral Contact Lenses to Alter Peripheral Refraction

The front optic zone diameter of scleral contact lenses was manipulated to mimic the central treatment zone induced by orthokeratology contact lens wear, to explore potential effects on the peripheral refraction profile. The purpose of this study was to investigate effects on the peripheral refraction profile of changing front optic zone diameters of scleral contact lenses. Twelve young adults were fitted with scleral contact lenses (diameter, 16.5 mm) with two front optic zone diameters (6 and 4 mm) on one eye only on 2 separate days. Both lenses were fabricated with front optic zone power of -3.00 D and plano power outside the optic zone to mimic the orthokeratology treatment effect. All lenses had the same spherical back-surface design with a toric lens periphery. Peripheral refraction was measured at 10° increments along horizontal (±35°) and vertical (±30°) meridians before lens insertion and after 10 minutes of lens wear. Mixed-model analysis and post hoc t tests with Bonferroni correction were performed. Compared with baseline, no significant change in relative spherical equivalent refraction M was observed with 6-mm optic zone lenses along the horizontal meridian. However, a significant difference in relative M profile was found with 4-mm optic zone lenses (P = .009). M became myopic at all locations in the nasal visual field (P < .05) except at 35°. In contrast, compared with baseline, no significant changes in relative M were found with either 6- or 4-mm optic zone lenses along the vertical meridian. The greater myopic shift in relative peripheral refraction with 4-mm compared with 6-mm front optic zone lenses suggests that a reduced treatment zone diameter in orthokeratology may induce more myopic peripheral refraction changes. This may guide us toward novel orthokeratology lens designs for more effective myopia control.

Peripheral Refraction in Myopic Children with and without Atropine Usage.

Purpose To compare the patterns of relative peripheral refractions of myopic children who were currently on atropine treatment for myopia control and myopic children who did not use atropine. Methods Chinese children (n = 209) aged 7 to 12 years participated in the study, 106 used atropine and 103 did not. Participants were also classified into three groups: emmetropes (SE: +0.50 to −0.50 D), low myopes (SE: −0.50 to −3.00 D), and moderate myopes (SE: −3.00 to −6.00 D). The central and peripheral refractions along the horizontal meridians (for both nasal and temporal fields) were measured in 10-degree steps to 30 degrees. Results There were no statistically significant differences in spherical equivalent and astigmatism of the three refractive groups in either the nasal or temporal retina. The atropine group showed a significant relative myopia in the temporal 30° field in spherical equivalent compared to the emmetropic group (t49 = 3.36, P=0.02). In eyes with low myopia, the atropine group had significant relative myopia in the nasal 30° and temporal 30° fields (t118 = 2.59, P=0.01; t118 = 2.06, P=0.04), and it is also observed at 20° and 30° of the nasal field for the moderate myopic group (t36 = 2.37, P=0.02; t2.84 = 2.84, P=0.01). Conclusion Significant differences in relative peripheral refraction were found between the atropine group and its controls. The findings suggested that the eyes that received atropine may have a less prolate shape and thus explain why using atropine is effective in controlling myopia progression.

Lower sensitivity to peripheral hypermetropic defocus due to higher order ocular aberrations.

Many myopia control interventions are designed to induce myopic relative peripheral refraction. However, myopes tend to show asymmetries in their sensitivity to defocus, seeing better with hypermetropic rather than myopic defocus. This study aims to determine the influence of chromatic aberrations (CA) and higher-order monochromatic aberrations (HOA) in the peripheral asymmetry to defocus. Peripheral (20° nasal visual field) low-contrast (10%) resolution acuity of nine subjects (four myopes, four emmetropes, one hypermetrope) was evaluated under induced myopic and hypermetropic defocus between ±5D, under four conditions: (a) Peripheral Best Sphere and Cylinder (BSC) correction in white light; (b) Peripheral BSC correction+CA elimination (green light); (c) Peripheral BSC correction+HOA correction in white light; and (d) Peripheral BSC correction+CA elimination+HOA correction. No cycloplegia was used, and all measurements were repeated three times. The slopes of the peripheral acuity as a function of positive and negative defocus differed, especially when the natural HOA and CA were present. This asymmetry was quantified as the average of the absolute sum of positive and negative defocus slopes for all subjects (AVS). The AVS was 0.081 and 0.063 logMAR/D for white and green light respectively, when the ocular HOA were present. With adaptive optics correction for HOA, the asymmetry reduced to 0.021 logMAR/D for white and 0.031 logMAR/D for green light, mainly because the sensitivity to hypermetropic defocus increased when HOA were corrected. The asymmetry was only slightly affected by the elimination of the CA of the eye, whereas adaptive optics correction for HOA reduced the asymmetry. The HOA mainly affected the sensitivity to hypermetropic defocus.

Stability of peripheral refraction changes in orthokeratology for myopia

PurposeOrthokeratology (OK) is known to alter relative peripheral refraction (RPR) with this presumed to be its key myopia control mechanism. A prospective, longitudinal study was performed to examine stability of OK-induced RPR changes in myopic children and young adults. MethodsRPR of twelve children (C)(8–16 years) and eight adults (A)(18–29 years) with spherical equivalent refraction of -0.75 to -5.00D were measured unaided and while wearing single vision soft contact lenses (SCL). Measurements were repeated after 1, 6 and 12 months of OK wear. RPR was measured using an open-field Shin Nippon SRW-5000 autorefractor at 10, 20 and 30 degrees nasally (N) and temporally (T), converted into power vectors M, J0 and J45. On-axis refractions and axial lengths (IOL Master) were also measured. ResultsCompared to the unaided state, 1-month of OK wear shifted the RPR in the myopic direction at 30 T (C: p = 0.023; A:, p = 0.002) and 30 N (C&A, p = 0.003) and was stable thereafter, with similar changes compared to SCL wear. J0 showed a myopic shift in comparison to both unaided and SCL correction in children but not adults, and J45 did not change in either group. The on-axis OK correction was predictive of the RPR shift in both children and adults at 30 T (C: r=−0.58, p = 0.029; A: r=−0.92, p < 0.001) and 30 N (C: r=−0.60, p = 0.024; A: r=−0.74, p = 0.013) with symmetry of RPR shifts (C: r = 0.67, p = 0.008; A: r = 0.85, p = 0.004). No relationships between changes in RPR and axial length were found after twelve months of OK wear; level of myopia was stable in both groups. ConclusionRelative to both unaided and single vision SCL correction, OK shifted the RPR in the myopic direction; the RPR was stable from 1 to 12 months. The RPR shift in OK wear varied with the degree of myopia but was not correlated with myopia progression.

Reducing treatment zone diameter in orthokeratology and its effect on peripheral ocular refraction

PurposeTo determine whether orthokeratology (OK) induced treatment zone (TZ) diameter can be reduced by altering OK lens design, and if so the impact of modifying TZ diameter on relative peripheral refraction (RPR). Methods16 subjects (mean age 23.4 ± 1.5 years; 8 female) completed the study. Standard (Control) OK lens design (PJ, Capricornia, Australia) or a modified version (Test) where the back optic zone diameter was reduced, and back optic zone asphericity and intermediate lens curves were altered, were worn overnight only for 7-nights in a randomised double masked order, with a minimum 1-week wash out (no lens wear) between lens designs. Full correction of refractive error was targeted. Refraction; best corrected visual acuity (BCVA); RPR (Shin-Nippon NVision-k 5001) along the horizontal and vertical meridians; and corneal topography (Medmont E300) were measured before starting lens wear and in the morning after lens removal after the seventh night of lens wear for both lens designs. TZ diameter and decentration was calculated from corneal topography. ResultsAfter 7-nights of wear both lens designs created -2.00D refraction effect with no significant difference in refractive effect or change to BCVA between the designs. The Test design created a significantly smaller horizontal (4.78 ± 0.37 vs 5.70 ± 0.37 mm, p < 0.001) and vertical (5.09 ± 0.51 vs 5.92 ± 0.51 mm p < 0.001) TZ diameter. The TZ was decentered inferior temporal with no significant difference between designs. There was no significant difference between the lens designs in RPR along the horizontal and vertical meridians at any measurement period. ConclusionsOK induced TZ diameter can be reliably reduced by altering OK lens design without detrimentally effecting lens centration or refractive effect. Reducing TZ diameter did not alter RPR, though measurement artifacts could be responsible for masking an effect. Longitudinal studies are needed to assess whether smaller TZ OK lens designs increase efficacy for slowing progression of myopia.

Two-dimensional Peripheral Refraction and Retinal Image Quality in Emmetropic Children

The relationship between the optical properties of the eye in the periphery and myopia development is still under debate. To further clarify this issue, we provide here baseline data of two-dimensional peripheral optics results in a group of emmetropic Chinese children. Peripheral aberrations were measured under cycloplegia by using an open-view Hartmann-Shack wavefront sensor (VPR, Voptica SL, Spain). This instrument allows to measure fast in the horizontal visual field from temporal 30° to nasal 30° every 1°. Two-dimensional (2D) maps were retrieved from a series of horizonal scans taken every 4° from 20° superior to 16° inferior covering a visual field of 60 × 36°. A relatively homogeneous pattern of the 2D relative peripheral refraction was found across all these emmetropic subjects. Using cluster analysis followed by manual visual refinement, the 2D maps were identified to fit into four categories. More than 70% of the subjects showed a nearly flat horizontal refraction with a slightly myopic shift in the superior retina. Peripheral astigmatism was quite constant across subjects and similar to that expected theoretically. Peripheral aberrations were also similar to those in the fovea for a large retinal area. These baseline data would offer an important reference to compare with the future evolution with time, as well as with other refractive or age groups of subjects, to better understand the role of peripheral optical properties in myopia development.

Effects of eye rotation and contact lens decentration on horizontal peripheral refraction.

Peripheral refraction is important in design of myopia control therapies. The aim was to investigate the influence of contact lens decentration associated with eye rotation on peripheral refraction in the horizontal visual field. Participants were 10 emmetropes and 10 myopes in good general and ocular health. Right eyes underwent cycloplegic peripheral refraction, using a Grand-Seiko WAM-5500 Autorefractor, in 5° steps to ±35° eccentricities along the horizontal visual field. Targets were fixated using eye rotation only or head rotation only. Refractions were measured without correction and with three types of contact lenses: single vision, a multifocal centre-distance aspheric with +2.50D add and NaturalVue aspheric. Photographs of eyes during lens wear were taken for each eye rotation. Effects of visual field angle, lens type and test method (head or eye rotation) on vector components of relative peripheral refraction were evaluated using repeated measures anovas. Test method for each visual field angle/lens combination were compared via paired t-tests. Horizontal decentration ranges across the visual field were 1.2±0.6mm for single vision and 1.2±0.4mm for multifocal lenses but smaller at 0.7±0.4mm for NaturalVue lenses. There were only two significant effects of test method across the visual field angle/lens type combinations (single vision: for emmetropes horizontal/vertical astigmatism component at 35° nasal with mean difference -0.38D and for myopes spherical equivalent refraction at 20° temporal with mean difference +0.24D). Upon eye rotation the contact lenses decentred on the eye, but not enough to affect peripheral refraction. For the types assessed and for the horizontal visual field out to ±35° when measurements were performed with the Grand-Seiko WAM-5500 autorefractor, it is valid to use eye rotations to investigate peripheral refraction.

Changes in relative peripheral refraction, HOAs and optical quality using a soft multifocal contact lens with different additions and optical zones

Purpose: The purpose of this study was to investigate the changes in relative peripheral refraction (RPR) and the effects on high order aberrations (HOAs) and objective optical quality induced by a CD soft multifocal CL, with different additions and central distant optical zones.