Nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control contact lens

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Purpose To evaluate the refractive impact of dual‐focus (DF) myopia control contact lenses (CLs) on accommodating young myopic adults. Methods Phase 1: accommodative accuracy was assessed in 40 myopic participants. Phase 2: a subset of four subjects who demonstrated accurate accommodation and six who chronically underaccommodated were fitted with single vision (SV, Proclear 1 day) and centre‐distance DF myopia control CLs (MiSight 1 day) with approximately +2.00 D of additional power in two surrounding annular zones. While binocularly viewing high contrast characters at 4.00, 1.00, 0.50, 0.33, 0.25 and 0.20 m, aberrometry data were captured across the central ±30° of the horizontal retina. Local refractive errors were pooled for each area of the pupil covered by the central distance or first annular defocus zone of the DF CLs. Results In the “good” accommodator group fitted with SV CLs, accommodative lags were generally absent except at the closest viewing distance (mean errors: −0.09 ± 0.22 D, −0.12 ± 0.26 D, −0.05 ± 0.37 D and +0.38 ± 0.54 D for −2.00, −3.00, −4.00 and −5.00 D target vergences, respectively) but significantly larger in the “poor” accommodating participants (+0.81 ± 0.21 D, +0.97 ± 0.27 D, +1.18 ± 0.39 D, +1.47 ± 0.55 D). For most viewing distances, hyperopic defocus observed in the region of the pupil covered by the first annular zone was replaced with myopic defocus when fitted with the DF CLs. Myopic defocus created by the first annular region was present across the central 30° of the retina. Conclusions Some young adult myopes chronically experience high levels of hyperopic defocus when viewing near targets, which was replaced by myopic defocus in the annular part of the pupil covered by the treatment zones when fitted with a centre‐distance myopia control DF CL.

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Retinal defocus in myopes wearing dual‐focus zonal contact lenses

Singh

Meyer

Jaskulski

et al. 2021

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“…Four commercially available MFCL lens types were used: MiSight concentric (+2.00 D add) (MS), Biofinity centre distance, continuous aspheric periphery with a +1.50 D (CD1) and a +2.50 D (CD2) add (all Coopervision, coopervision.com) and NaturalVue aspheric (Visioneering Technologies, vtivision.com) (NVue) which is reported by the manufacturers to be a ‘single high add’ and reaches a maximum relative plus power of +3 D to 5 D by 2.75 mm to 2.9 mm semi‐diameter ( Figure ) 29,30 . Each MFCL lens has a single base curve and single diameter, and all have been investigated for myopia control efficacy in children 8,31–34 .…”

Section: Methodsmentioning

confidence: 99%

“…com) and NaturalVue aspheric (Visioneering Technologies, vtivision.com) (NVue) which is reported by the manufacturers to be a 'single high add' and reaches a maximum relative plus power of +3 D to 5 D by 2.75 mm to 2.9 mm semi-diameter (Figure 1). 29,30 Each MFCL lens has a single base curve and single diameter, and all have been investigated for myopia control efficacy in children. 8,[31][32][33][34] One SVD CL was used for comparison purposes: Proclear lens (Coopervision) (SV).…”

Section: Lensesmentioning

confidence: 99%

Multifocal contact lens design, not addition power, affects accommodation responses in young adult myopes

Gifford

Schmid

Collins

et al. 2021

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Purpose Prolonged nearwork has been implicated in myopia progression. Accommodation responses of young‐adult myopes wearing different multifocal contact lenses were compared. Methods Twenty adults, 18–25 years, with myopia (spherical equivalent refraction −0.50 to −5.50 D, mean −2.1 ± 1.6 D) wore five lens types in random order: Proclear single vision distance (SV), MiSight concentric dual‐focus +2.00 D Add (MS), Biofinity aspheric centre distance +1.50 D Add (CD1) and +2.50 D Add (CD2) (all Coopervision), and NaturalVue aspheric (Visioneering Technologies) (NVue). Using a Grand‐Seiko WAN‐5500 autorefractor with binocular correction and viewing right eye accommodative responses were measured after a 10 min adaptation period at 4.0, 1.0, 0.5, 0.33 and 0.25 m distances. Dynamic measurements were taken for 4 s at 6 Hz. Accommodative stimuli and responses were referenced to 4 m (i.e., refraction differences between 4 m and nearer distances). Accommodation lags and refraction instabilities (standard deviations of dynamic responses) were determined. For comparison, results were obtained for an absolute presbyopic eye, where trial lenses counteracted the accommodation stimulus. Results For SV and MS, accommodation responses were similar to the stimulus values. For aspheric lenses CD1, CD2 and NVue, accommodation responses were approximately 1.0 D lower across the stimulus range than with SV and MS, and rates of change were approximately 0.84 D per 1 D stimulus change. MS produced greater refraction instabilities than other lenses. For the presbyope, changes in refraction matched the trial lenses, indicating that corrections due to measurement through the different lenses were not needed. Conclusion Reductions in accommodation response occurred in young myopes wearing aspheric multifocal contact lenses independent of the labelled ‘add’ power. The concentric dual‐focus MS lens produced minimal lags but had greater instability than the other lenses. The results indicate that the mechanism of multifocal contact lenses slowing myopia progression is unlikely to be through relaxing accommodation, at least in young adults.

“…The lens was based on the NaturalVue contact lens (VTI, vtivision.com) which has an increase in sagittal power by approximately 4 D at a diameter of 6 mm. 20,21 It has a front surface with a central zone apical radius of curvature of 7.72 mm, matching that of the Navarro anterior cornea, but with conic asphericity Q = +0.753. A peripheral zone beyond a 6 mm diameter was continuous with the central zone, but was spherical with a 7.72 mm radius of curvature.…”

Section: Modelling and Raytrace Simulationsmentioning

confidence: 97%

The use of autorefractors using the image‐size principle in determining on‐axis and off‐axis refraction. Part 2: Theoretical study of peripheral refraction with the Grand Seiko AutoRef/Keratometer WAM‐5500

Atchison

Suheimat

Zacharovas

et al. 2021

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Purpose: To determine, through simulations, the likely validity of Grand-Seiko autorefractors with annular targets in peripheral refraction.Methods: Using a physical model eye, the distance inside the eye to which the Grand Seiko AutoRef/Keratometer WAM-5500 beam was converging and the effective size of its outer diameter at the cornea were determined. Grand-Seiko refraction was calculated from R x = (θ + α)/h 1 , where θ is the angle of the ingoing radiation beam, h 1 is the height of the beam at the anterior cornea and α is the angle of the beam emerging from the eye following reflection at the retina. Two eye models were used: a Navarro schematic eye and a Navarro schematic eye with a contact lens having a highly positive aspheric front surface. Results:The instrument beam was determined to be converging towards the eye to a distance of 24.4 mm behind the corneal vertex, with a 2.46 mm effective size outer diameter of the beam at the anterior cornea. The Grand-Seiko refractions provided accurate estimates of peripheral refraction for the model eyes.The results were closer to Zernike refractions than to Zernike paraxial refraction. Spherical aberration influenced refraction by up to 0.5 D, and peripheral coma had limited influence. Conclusion:Grand-Seiko autorefractors in current use, and having a circular annulus with an ingoing effective outer diameter at the front of the eye of about 2.4 mm, are likely to give valid peripheral refractions.