Changes In Peripheral Refraction Research Articles

Study of peripheral blur in retinal electrical activity

Aims/Purpose: The aim of this study was to evaluate changes in peripheral refraction by the use of a contact lens to control the progression of myopia. In addition, the response of electrophysiological activity in different areas of the retina with and without contact lens was also determined.Methods: We recruited 7 myopic individuals (23.71 ± 5.41 years) with refraction up to −4.50D (spherical equivalent), without eye pathologies and surgeries. Visual acuity was recorded, high and low contrast, with the updated refraction and with the Misight 1 Day contact lens. Peripheral refraction measurements were obtained using an open‐field autorefractometer. Multifocal electrophysiology measurements were performed binocularly with and without contact lens, with dilated pupil. Topography and aberrometry values were also recorded.Results: lens, peripheral refractions become significantly more myopic. The change in peripheral refraction induced at 30° Nasal is −0.66D. High Contrast Visual Acuity was always superior to Low Contrast VA in both conditions. The Misight 1 Day contact lens manifests a different behaviour along the anterior surface of the cornea. LC induces a significant increase in high‐order aberrations, especially in comatic aberrations, which increase three times their initial value.Conclusions: Regarding the electrophysiological response of the retina, with the use of the LC Misight 1 Day, it presented a greater implicit time and amplitude of the P1 component, in the superior temporal retina, these differences being statistically significant. The implicit time of the P2 component increased in the temporal retina and in the retinal area delimited by Rings 3, 4 and 5.

The Influence of Accommodation on Retinal Peripheral Refraction Changes in Different Measurement Areas.

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.

Nasal-temporal asymmetric changes in retinal peripheral refractive error in myopic adolescents induced by overnight orthokeratology lenses.

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.

Peripheral Refraction With Toric Orthokeratology and Soft Toric Multifocal Contact Lenses in Myopic Astigmatic Eyes.

PurposeThere has been little research on myopia management options for patients with astigmatism. This study quantified changes in peripheral refraction induced by toric orthokeratology (TOK) and soft toric multifocal (STM) contact lenses.MethodsThirty adults with refractive error of plano to −5.00 D (sphere) and −1.25 to −3.50 D (cylinder) were enrolled. Cycloplegic autorefraction was measured centrally, ±20 degrees, and ±30 degrees from the line of sight nasally (N) and temporally (T) on the retina. Measurements were made at baseline, after 10 ± 2 days of TOK wear (without lenses on eye), and after 10 ± 2 days of STM wear (with lenses on the eyes) and compared with repeated-measures analysis of variance.ResultsCompared to baseline, TOK induced a myopic shift in defocus (M) at all locations (all P < 0.01), but STM only induced a myopic shift at 20 T in both eyes and 30 N/T in the left eye (all P < 0.01). TOK resulted in more myopic defocus than STM at all locations (all P < 0.05) except 20 T in the left eye. TOK induced more J0 astigmatism at all locations (all P < 0.02), except 20 N in the right eye; J0 with STM was different than baseline at 20 N in both eyes and 30 N in the right eye (all P < 0.02). TOK induced more J0 astigmatism than STM at all locations (all P < 0.01), except 20 T in the left eye. Differences in J45 astigmatism, when significant, were clinically small.ConclusionsGreater amounts of peripheral myopic defocus and J0 astigmatism were induced by TOK compared to STM, which may influence efficacy for myopia management.

Power profiles of centre-distance multifocal soft contact lenses.

Centre-distance multifocal contact lenses (MFCLs) for myopia control are thought to slow myopia progression by providing both clear foveal vision and myopic defocus. Characterising the power profile of lenses is important to understanding their possible effects on retinal defocus when worn. The power profiles of three commercially available MFCLs were determined. Three centre-distance MFCL designs were studied: Biofinity Multifocal D +2.50 add (comfilcon A), Proclear Multifocal D +2.50 add (omafilcon A), and NaturalVue Multifocal (etafilcon A). Two lenses each in power from -1.00D to -6.00D in 1D steps were stored in ISO 18369-3:2017 standard phosphate buffered saline for 24h. Optical power profiles were measured in a wet cell with the SHSOphthalmic profiler accounting for centre thickness and manufacturer-reported material refractive index. Sagittal power maps from the SHSOphthalmic were exported, and custom MATLAB code was used to generate power profiles by averaging along the vertical and horizontal meridians. One-way anova with Tukey's HSD post-hoc t-tests were used to analyse maximum add power by lens design. Plus power increased out from the lens centre for all three MFCLs. Power profiles of Biofinity D and Proclear D MFCLs show three distinct areas within the optic zone; the distance zone (from lens centre to about 1.6mm radius), intermediate zone (about 1.6mm radius to 2.1mm) and near zone (about 2mm radius to 4mm). For NaturalVue MFCLs, plus power starts increasing almost immediately from the lens centre, reaching maximum measured mean plus power at a radius of 2.7mm. From 2.7mm to 3.0mm, there was a decrease in plus power, which was then generally maintained out to the optic zone edge. Across all lens powers, maximum add power was highest with the NaturalVue MFCL (+3.32±0.44D), then Proclear D (+1.84±0.28D) and Biofinity D (+1.47±0.34D) MFCLs (all p<0.04). Add power peaked at different locations for different lens powers and designs. Power profiles of MFCLs vary based on lens design and power. These power profiles are consistent with reported myopic and hyperopic changes in peripheral refraction with MFCLs and provide some explanation for reported differences in peripheral refraction with these MFCLs. Further work is needed to determine whether these power profile differences influence myopia progression.

Различия профиля периферического дефокуса после ортокератологической и эксимерлазерной коррекции миопии

A variety of factors that change the topography of the cornea may also induce changes in peripheral refraction. Purpose. The paper is aimed at assessing the peripheral refraction and retinal contour of myopic eyes after FS-LASIK and orthokeratological (Ortho-k) correction. Materials and methods. We examined a total of 30 patients (60 eyes) aging from 28.86 ±2.83 years which included 12 patients (24 eyes) with myopia of -5.11 ± 0.5 D and with an axial length (AL) of 25.04 ±0.33 mm before and 1 month after FS-LASIK surgery, and also included 18 patients (36 eyes) with myopia of -5.4 ± 0.24 D and AL of 25.78 ± 0.2 mm who wore ESA-DL Ortho-k lenses. The peripheral refraction of all the patients was measured using the Grand Seiko Open-field binocular autoref/keratometer and the peripheral eye length was measured using the IOL Master 500 (Carl Zeiss) at 15° and 30o nasally (N) and temporally (T), respectively, from the center of fovea. Results. The peripheral eye length measured before and after FS-LASIK as well as after Ortho-k correction was less in all peripheral zones than in the center, which corresponds to characteristics observed in hyperopic peripheral defocus. Refraction measured after FS-LASIK showed the formation of myopic defocus with a maximum at 30° from the following results: -2.49 D at T15°, -2.5 D at N15°, -6.73 D at T30°, and -7.8 D at N30°. The maximal myopic defocus after Ortho-k correction was detected in the middle periphery from these following results: -4.89 D at T15°, -5.51 D at N15°, -2.92 D at T30° and -2.4 D at N30°. Conclusions. Both procedures induced a significant peripheral myopic defocus. In the first case, the maximum values of defocus were detected in the peripheral zone (30° from the center of the fovea); in the second case, the maximal effect on the middle periphery was identified 15° from the center. Such patterns of peripheral refraction fully coincided with the specific changes in corneal topography after the two procedures. The retinal contour within 30° from the center retained the relative hyperopic defocus characteristic of intact myopic eyes // Russian Ophthalmological Journal, 2017; 1: 31-5. doi: 10.21516/2072-0076-2017-10-1-31-35.

Changes in Peripheral Refraction, Higher-Order Aberrations, and Accommodative Lag With a Radial Refractive Gradient Contact Lens in Young Myopes.

To evaluate changes in the peripheral refraction (PR), visual quality, and accommodative lag with a novel soft radial refractive gradient (SRRG) experimental contact lens that produces peripheral myopic defocus. 59 myopic right eyes were fitted with the lens. The PR was measured up to 30° in the nasal and temporal horizontal visual fields and compared with values obtained without the lens. The accommodative lag was measured monocularly using the distance-induced condition method at 40 cm, and the higher-order aberrations (HOAs) of the entire eye were obtained for 3- and 5-mm pupils by aberrometry. Visual performance was assessed through contrast sensitivity function (CSF). With the lens, the relative PR became significantly less hyperopic from 30° to 15° temporally and 30° nasally in the M and J0 refractive components (P<0.05). Cylinder foci showed significant myopization from 30° to 15° temporally and 30° to 25° nasally (P<0.05). The HOAs increased significantly, the CSF decreased slightly but reached statistical significance for 6 and 12 cycles per degree (P<0.05), and the accommodative lag decreased significantly with the SRRG lens (P=0.0001). There was a moderate correlation between HOAs and CSF at medium and high spatial frequencies. The SRRG lens induced a significant change in PR, particularly in the temporal retina. Tangential and sagittal foci changed significantly in the peripheral nasal and temporal retina. The decreased accommodative lag and increased HOAs particularly in coma-like aberration may positively affect myopia control. A longitudinal study is needed to confirm this potential.

Abstracts from the 15th International Myopia Conference

Table of contentsO1 Changes in peripheral refraction associated with decreased ocular axial growth rate in marmosetsAlexandra Benavente-Perez, Ann Nour, Tobin Ansel, Kathleen Abarr, Luying Yan, Keisha Roden, David TroiloO2 PPARα activation suppresses myopia development by increasing scleral collagen synthesis--a new drug target to suppress myopia developmentChanyi Lu, Miaozhen Pan, Min Zheng, Jia Qu, Xiangtian ZhouO3 Evidence and possibilities for local ocular growth regulating signal pathwaysChristine F WildsoetO4 Myopia researches at Eye Hospital of Wenzhou Medical UniversityFan Lu, Xiangtian Zhou, Jie Chen, Jinhua Bao, Liang Hu, Qinmei Wang, Zibing Jin, Jia QuO5 Color, temporal contrast and myopiaFrances Rucker, Stephanie Britton, Stephan Hanowsky, Molly SpatcherO6 The impact of atropine usage on visual function and reading performance in myopic school children in TaiwanHui-Ying Kuo, Ching-Hsiu Ke, I-Hsin Kuo, Chien-Chun Peng, Han-Yin SunO7 Increased time outdoors prevents the onset of myopia: evidence from randomised clinical trialsIan G MorganO8 Environmental risk factors and gene-environment interactions for myopia in the ALSPAC cohortJeremy A. Guggenheim, Rupal L. Shah, Cathy WilliamsO9 Retinal metabolic profiling identifies declines in FP receptor-linked signaling as contributors to form-deprived myopic development in guinea pigsJinglei Yang, Peter S. Reinach, Sen Zhang, Miaozhen Pan, Wenfeng Sun, Bo Liu, Xiangtian ZhouO10 The study of peripheral refraction in moderate and high myopes after one month of wearing orthokeratology lensJun Jiang, Haoran Wu, Fan LuO11 Axial length of school children around the earth’s equatorial area and factors affecting the axial lengthKazuo Tsubota, Hiroko Ozawa, Hidemasa Torii, Shigemasa Takamizawa, Toshihide Kurihara, Kazuno NegishiO12 Processing of defocus in the chicken retina by retinal ganglion cellsKlaus Graef, Daniel Rathbun, Frank SchaeffelO13 Blue SAD light protects against form deprivation myopia in chickens, by local signaling within the retinaLadan Ghodsi, William K. StellO14 Contributions of ON and OFF pathways to emmetropization and form deprivation myopia in miceMachelle T. Pardue, Ranjay Chakraborty, Han na Park, Curran S. Sidhu, P. Michael IuvoneO15 Response of the human choroid to defocusMichael J CollinsO16 What can RNA sequencing tell us about myopic sclera?Nethrajeith Srinvasalu, Sally A McFadden, Paul N BairdO17 Overview of dopamine, retinal function, and myopiaP. Michael IuvoneO18 The eye as a "robust" optical system and myopiaPablo ArtalO19 Effect of discontinuation of orthokeratology lens wear on axial elongation in childrenPauline Cho, SW CheungO20 Myopia prevention in TaiwanPei-Chang WuO21 Alternatives to ultraviolet light and riboflavin for in vivo crosslinking of scleral collagenQuan V. Hoang, Sally A. McFaddenO22 Absence of intrinsically photosensitive retinal ganglion cells (ipRGC) alters normal refractive development in miceRanjay Chakraborty, Duk C. Lee, Erica G. Landis, Michael A. Bergen, Curran Sidhu, Samer Hattar, P. Michael Iuvone, Richard A. Stone, Machelle T. PardueO23 Scleral micro-RNAs in myopia development and their potential as therapeutic targetsRavi MetlapallyO24 Effects of the long-wavelength filtered continuous spectrum on emmetropization in juvenile guinea pigsRuiqin Li, Qinglin Xu, Hong Zhon, Chenglin Pan, Weizhon Lan, Xiaoning Li, Ling Chen, Zhikuan YangO25 Ocular and environmental factors associated with eye growth in childhoodScott A. ReadO26 Overview- prevention and prediction of myopia and pathologic myopiaSeang-Mei SawO27 New insights into the roles of retinal dopamine in form-deprivation myopia and refractive development in C57BL/6 miceShi-Jun Weng, Xiao-Hua Wu, Kang-Wei Qian, Yun-Yun Li, Guo-Zhong Xu, Furong Huang, Xiangtian Zhou, Jia Qu, Xiong-Li Yang, Yong-Mei ZhongO28 The effects of the adenosine antagonist, 7-methylxanthine, on refractive development in rhesus monkeysEarl L Smith III, Baskar Arumugam, Li-Fang Hung, Lisa A. Ostrin, Klaus Trier, Monica Jong, Brien A. HoldenO29 Application of SWATH™ based next generation proteomics (NGP) in studying eye growth: opportunities and challengesThomas Chuen Lam, Bing Zuo, Samantha Shan, Sally A. McFadden, Dennis Yan-yin Tse, Jingfang Bian, King-Kit Li, Quan Liu, Chi-ho ToO30 How could emmetropization make use of longitudinal chromatic aberration?Timothy J. Gawne, John T. Siegwart Jr., Alexander H. Ward, Thomas T. NortonO31 Balance effect of dopamine D1 and D2 receptor subtype activation on refraction developmentXiangtian ZhouO32 BMP gene expression changes in chick rpe in response to visual manipulationsYan Zhang, Yue Liu, Carol Ho, Eileen Phan, Abraham Hang, Emily Eng, Christine Wildsoet

Peripheral refraction and retinal contour after FS‐LASIK and orthokeratology

PurposeA variety of factors that change the topography of the cornea may also induce changes in peripheral refraction. The paper is aimed at assessing the peripheral refraction and retinal contour of myopic eyes after FS‐LASIK and orthokeratological (OK) correction.MethodsWe examined 30 patients (60 eyes) including 12 patients (24 eyes) aged 28.86 ± 2.83 years with myopia of −5.11 ± 05 D on average, and axial length (AL) = 25.04 ± 0.33 mm before FS‐LASIK and 1 month after it and 18 patients (36 eyes) with myopia of −5.4 ± 0.24 D on average, AL = 25.78 ± 0.2 mm who wore ESA‐DL OK‐lenses. All patients were tested for peripheral refraction on Grand Seiko Open‐field binocular autoref/keratometer and had their peripheral eye length measured on IOL Master 500 (Carl Zeiss) at 15° and 30° nasally (N) and temporally (T) from the center of fovea.ResultsThe peripheral eye length measured before and after FS‐LASIK as well as after OK‐correction was less in all peripheral zones than the central length, which corresponds to hyperopic peripheral defocus. Refraction measured after FS‐LASIK showed the formation of myopic defocus with a maximum at 30°: T15° ‐2.49 D, N15° ‐2.5 D, T30° ‐6.73 D and N30° ‐7.8 D. The maximal myopic defocus after OK‐correction is detected in the middle periphery: −4.89 D at T15°, −5.51 D at N15°, −2.92 D at T30° and 2.4 D at N30°.ConclusionsBoth procedures induce a significant peripheral myopic defocus. In the first case, the maximum values of defocus is detected in the peripheral zone (at 30° from the center of the fovea), in the second case it affects the middle periphery (15° from the center) most of all. Such patterns of peripheral refraction fully coincide with the specific changes in corneal topography after the two procedures. The retinal contour within 30° from the center retains the relative hyperopic defocus characteristic of intact myopic eyes.

The Influence of Different OK Lens Designs on Peripheral Refraction.

To compare peripheral refraction changes along the horizontal and vertical meridians induced by three different orthokeratology (OK) lens designs: BE, Paragon CRT, and Contex lenses. Nineteen subjects (6M, 13F, mean age 28 ± 7 years) were initially fitted with BE OK lenses in both eyes which were worn overnight for 14 days. Central and peripheral refraction and corneal topography were measured at baseline and after 14 nights of lens wear. After a minimum 2-week washout period, one randomly selected eye was re-fitted with a Paragon CRT lens and the other eye with a Contex OK lens. Measurements were repeated before and after 14 nights of lens wear. The three different OK lenses caused significant changes in peripheral refraction along both the horizontal and vertical visual fields (VFs). BE and Paragon CRT lenses induced a significant hyperopic shift within the central ±20° along the horizontal VF and at all positions along the vertical meridian except at 30° in the superior VF. There were no significant differences in peripheral refraction changes induced between BE and Paragon CRT lenses. When comparing BE and Contex OK lens designs, BE caused greater hyperopic shifts at 10° and 30° in the temporal VF and at center, 10°, and 20° in the superior VF along the vertical meridian. Furthermore, BE lenses caused greater reduction in Flat and Steep K values compared to Contex OK. OK lenses induced significant changes in peripheral refraction along the horizontal and vertical meridians. Despite the clinically significant difference in central corneal flattening induced by BE and Contex OK lenses, relative peripheral refraction changes differed minimally between the three OK lens designs. If the peripheral retina influences refractive error development, these results suggest that myopia control effects are likely to be similar between different OK lens designs.

New Perspective on Myopia Control with Orthokeratology.

To compare peripheral refraction along both the horizontal and vertical retinal meridians before and after orthokeratology (OK) lens wear. Nineteen young adult myopic subjects (mean age, 28 ± 7 years) were fitted with OK lenses in both eyes. Central and peripheral refraction and corneal topography measurements were taken before and after 14 nights of OK. All measurements were taken with no correction or OK lens in place. At baseline before OK, peripheral spherical equivalent refraction (M) across the horizontal meridian did not vary significantly from center. M across the vertical meridian was more myopic than the center (p < 0.05). After OK, there was a significant hyperopic shift in M (p < 0.001); both meridians now experienced myopic peripheral refraction. At baseline, J180 across the horizontal meridian was more negative than the center, and along the vertical meridian, it was more positive than the center (all p < 0.05). At baseline, J45 was more positive than center with increased eccentricity in the temporal and inferior retina and more negative than center with increased eccentricity in the nasal and superior retina. Orthokeratology caused greater rate of change of peripheral J180 across both retinal meridians (p < 0.001). Furthermore, compared with baseline, J45 became more positive in the nasal and superior retina and more negative in the temporal and inferior retina (all p < 0.05). Orthokeratology lenses induced significant changes in peripheral refraction along the horizontal and vertical meridians. As peripheral myopia was measured at baseline along the vertical meridian, the results of our study suggest that inducing greater degrees of myopic defocus on to the peripheral retina, more than habitually experienced, may be required for effective myopia control. Further investigation into the critical threshold of retinal area receiving myopic defocus and the impact of duration of exposure is necessary to improve the efficacy of current myopia control treatments.

The BHVI-EyeMapper: peripheral refraction and aberration profiles.

ABSTRACTPurposeThe aim of this article was to present the optical design of a new instrument (BHVI-EyeMapper, EM), which is dedicated to rapid peripheral wavefront measurements across the visual field for distance and near, and to compare the peripheral refraction and higher-order aberration profiles obtained in myopic eyes with and without accommodation.MethodsCentral and peripheral refractive errors (M, J180, and J45) and higher-order aberrations (C[3, 1], C[3, 3], and C[4, 0]) were measured in 26 myopic participants (mean [±SD] age, 20.9 [±2.0] years; mean [±SD] spherical equivalent, −3.00 [±0.90] diopters [D]) corrected for distance. Measurements were performed along the horizontal visual field with (−2.00 to −5.00 D) and without (+1.00 D fogging) accommodation. Changes as a function of accommodation were compared using tilt and curvature coefficients of peripheral refraction and aberration profiles.ResultsAs accommodation increased, the relative peripheral refraction profiles of M and J180 became significantly (p < 0.05) more negative and the profile of M became significantly (p < 0.05) more asymmetric. No significant differences were found for the J45 profiles (p > 0.05). The peripheral aberration profiles of C[3, 1], C[3, 3], and C[4, 0] became significantly (p < 0.05) less asymmetric as accommodation increased, but no differences were found in the curvature.ConclusionsThe current study showed that significant changes in peripheral refraction and higher-order aberration profiles occurred during accommodation in myopic eyes. With its extended measurement capabilities, that is, permitting rapid peripheral refraction and higher-order aberration measurements up to visual field angles of ±50 degrees for distance and near (up to −5.00 D), the EM is a new advanced instrument that may provide additional insights in the ongoing quest to understand and monitor myopia development.

Can Manipulation of Orthokeratology Lens Parameters Modify Peripheral Refraction?

To investigate changes in peripheral refraction, corneal topography, and aberrations induced by changes in orthokeratology (OK) lens parameters in myopes. Subjects were fitted with standard OK lenses that were worn overnight for 2 weeks. Peripheral refraction, corneal topography, and corneal surface aberrations were measured at baseline and after 14 nights of OK lens wear. Subsequent to a 2-week washout period, subjects were refitted with another set of lenses where one eye was randomly assigned to wear an OK lens with a smaller optic zone diameter (OZD) and the other eye with a steeper peripheral tangent. Measurements were taken again at a second baseline and after 14 days of overnight wear of the second OK lens set. Standard OK lenses with a 6-mm OZD and 1/4 peripheral tangent caused significant changes in both peripheral refraction and corneal topography. Significant hyperopic shift occurred in the central visual field (VF) while a myopic shift was found at 35 degrees in the nasal VF. OK induced significant reductions in corneal power at all positions along the horizontal corneal chord except at 2.4 mm nasal where there was no significant change and at 2.8 mm nasal where there was an increase in corneal refractive power. A positive shift in spherical aberration was induced for all investigated lens designs except for the 1/2 tangent design when calculated over a 4-mm pupil. Reducing OZD and steepening the peripheral tangent did not cause significant changes in peripheral refraction or corneal topography profiles across the horizontal meridian. OK lenses caused significant changes in peripheral refraction, corneal topography, and corneal surface aberrations. Modifying OZD and peripheral tangent made no significant difference to the peripheral refraction or corneal topography profile. Attempting to customize refraction and topography changes through manipulation of OK lens parameters appears to be a difficult task.

The Effect of Multifocal Soft Contact Lenses on Peripheral Refraction

To compare changes in peripheral refraction with single-vision (SV) and multifocal (MF) correction of distance central refraction with commercially available SV and MF soft contact lenses (SCLs) in young myopic adults. Thirty-four myopic adult subjects were fitted with Proclear Sphere and Proclear Multifocal SCLs to correct their manifest central refractive error. Central and peripheral refraction were measured with no lens wear and subsequently with the two different types of SCL correction. At baseline, refraction was myopic at all locations along the horizontal meridian. Peripheral refraction was relatively hyperopic compared with center at 30 and 35 degrees in the temporal visual field (VF) in low myopes, and at 30 and 35 degrees in the temporal VF, and 10, 30, and 35 degrees in the nasal VF in moderate myopes. Single-vision and MF distance correction with Proclear Sphere and Proclear Multifocal SCLs, respectively, caused a hyperopic shift in refraction at all locations in the horizontal VF. Compared with SV correction, MF SCL correction caused a significant relative myopic shift at all locations in the nasal VF in both low and moderate myopes and also at 35 degrees in the temporal VF in moderate myopes. Correction of central refractive error with SV and MF SCLs caused a hyperopic shift in both central and peripheral refraction at all positions in the horizontal meridian. Single-vision SCL correction caused the peripheral retina, which initially experienced absolute myopic defocus at baseline with no correction to experience an absolute hyperopic defocus. Multifocal SCL correction resulted in a relative myopic shift in peripheral refraction compared with SV SCL correction. This myopic shift may explain recent reports of reduced myopia progression rates with MF SCL correction.

Time course of the effects of orthokeratology on peripheral refraction and corneal topography

To describe the time course of changes in both peripheral refraction and corneal topography in myopic adults wearing myopic orthokeratology (OK) lenses. Nineteen adult myopes were fitted with OK lenses in both eyes for overnight wear. Central and peripheral refraction and corneal topography were measured along the horizontal meridian at baseline and after 1, 4, 7 and 14 nights of lens wear. At baseline, refraction was myopic at all positions along the horizontal meridian. Two weeks of OK lens wear caused a significant change in refraction where the general trend was a hyperopic shift in spherical equivalent (M) except at 35° in the nasal visual field where there was instead a myopic shift in M. The most significant change in M occurred between baseline and after 1 night of OK lens wear and the effect became less dramatic across subsequent days of OK treatment. Similarly, OK caused significant change in corneal refractive power at all positions along the horizontal corneal chord. There was a reduction in corneal power or flattening of the cornea at all positions except at 2.4 mm and 2.8 mm on the nasal cornea where there was an increase in corneal refractive power or steepening of the cornea. This change was most apparent after 1 night of OK lens wear and, similar to changes in peripheral refraction, changes in corneal refractive power on subsequent days of OK treatment became less marked. Orthokeratology caused significant changes in both peripheral refraction and corneal topography. The greatest change in refraction and corneal refractive power across the horizontal corneal meridian occurred during the first night of OK lens wear. Subsequent changes in both peripheral refraction and corneal topography were less dramatic, in the same manner as reported changes in apical radius and central refraction after OK. This study confirms that with OK treatment, the peripheral retina experiences myopic defocus, which is conjectured to underlie the observed slowing of myopia progression.

Effect of Single Vision Soft Contact Lenses on Peripheral Refraction

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.

Peripheral Refraction in Myopic Children Wearing Orthokeratology and Gas-Permeable Lenses

To investigate changes in peripheral refraction after orthokeratology (OK) and rigid gas-permeable (GP) lens wear in progressing myopic children and to compare these peripheral defocus changes with reported changes in adults wearing OK. Sixteen myopic children subjects were fitted with an OK lens in one eye for overnight wear and a GP lens in the other eye for daily wear. Central and peripheral refraction were measured at baseline and then after 3 mo of lens wear. At baseline, myopic children showed relative peripheral hyperopia compared with central refraction at and beyond 20° in the temporal visual field (VF) and 30° in the nasal VF. Three months of OK lens wear produced hyperopic shifts in refraction between 30° in the temporal VF and 20° in the nasal VF. Peripheral refraction was similar to center at all positions in the temporal VF while remaining significantly myopic at all locations in the nasal VF. No change in either central or peripheral refraction was found after 3 mo in the eye assigned for GP lens wear. OK significantly reduced myopia in the central 20° VF in myopic children, converting relative peripheral hyperopia measured at baseline to relative peripheral myopia. These changes in children are similar to changes reported in myopic adults wearing OK lenses. No change in either central or peripheral refraction was found after 3 mo of daily GP lens wear. OK lenses can be used to induce myopic defocus in the periphery in myopic children and may thus provide a potential mechanism for myopia control.

Aberrations of emmetropic subjects at different ages

We made on-axis aberrations and horizontal peripheral refraction measurements of emmetropic subjects (spherical equivalent −0.88 D to +0.75 D) aged between 19 and 70 years. We found smaller changes in on-axis aberrations with age than has previously been reported, possibly because of the small refractive error range of our subject group. Higher order root-mean-squared aberrations increased by 26% across the age range (5 mm pupils), with significant age related changes in 4th- and 6th-order aberrations. The only aberration co-efficient to change significantly was horizontal coma co-efficient C(3, 1). Several aberration co-efficients were significantly different from zero across the group of subjects. The only changes in peripheral refraction with increase in age were shifts in the turning points of the spherical equivalent and horizontal/vertical astigmatism towards less temporal visual field angles.

Peripheral refraction for distance and near vision in emmetropes and myopes

We investigated the relationship between myopia and peripheral refraction for distance and near vision by measuring peripheral refractive errors in 10 myopic and 10 emmetropic participants at viewing distances of 2.5 and 0.4 m. Measurements were made at the fovea, and at eccentricities of 10 degrees , 20 degrees and 30 degrees in the temporal and nasal hemispheres of the horizontal visual field. Our results showed that peripheral astigmatism increased with increasing eccentricity, but there was no significant difference between refractive error groups except at 30 degrees eccentricity in the temporal retina. Considering the Mean Spherical Equivalent errors, emmetropes became relatively myopic at peripheral eccentricities, but there was little change in myopes. The effect of viewing distance on astigmatism or Mean Spherical Equivalent error was not significant. Our results do not support the view that myopia is associated with changes in peripheral refraction during distance or near vision.

Longitudinal changes in peripheral refraction with age

The changes in the patterns of refraction (skiagrams) over the central +/-35 degrees of the horizontal field of 3 originally near-emmetropic eyes of 2 subjects were determined over a time interval of 26 years. The subjects were aged 32 and 40 years at the time of the first measurements. The central refractions shifted in the expected hyperopic direction, while the radial and tangential image fields in the periphery became more myopic. These longitudinal results agree with recent transverse studies, provided that allowance is made for the change in central refraction: the reported loss with age in peripheral visual performance does not seem to be attributable to markedly increased peripheral astigmatism.