Effect of multifocal spectacle lenses on accommodative errors over time: Possible implications for myopia control.

The study purpose was to improve understanding of how multifocal spectacle lenses affect accommodative errors and whether this changes over time. Fifty-two myopes aged 18 to 27 years were allocated randomly to one of two progressive addition lens (PAL) types with 1.50 D additions and different horizontal power gradients across the near-periphery boundary. Lags of accommodation were determined with a Grand Seiko WAM-5500 autorefractor and a COAS-HD aberrometer for several near distances with the distance correction and the near PAL correction. For the COAS-HD the neural sharpness (NS) metric was used. Measures were repeated at three-month intervals over 12 months. At the final visit, lags to booster addition powers of 0.25, 0.50, and 0.75 D were measured. Except at baseline, both PALs' data were combined for analysis. For the Grand Seiko autorefractor, both PALs reduced accommodative lag at baseline compared with SVLs (p < 0.05 and p < 0.01 at all distances for PAL 1 and PAL 2, respectively). For the COAS-HD, at baseline PAL 1 reduced accommodative lag at all near distances (p < 0.02), but PAL 2 only at 40 cm (p < 0.02). Lags measured with COAS-HD were greater for shorter target distances with PALs. After 12 months' wear, the PALs no longer reduced accommodative lags significantly, except at 40 cm distance, but 0.50 D and 0.75 D booster adds decreased the lags to those measured at baseline or less. In conclusion, for PALs to reduce accommodative lag effectively, addition power should be tailored to typical working distances and after the first year of wear should be boosted by at least 0.50 D to maintain efficacy.

Accommodation lags are higher in myopia than in emmetropia: Measurement methods and metrics matter.

PURPOSE: To determine whether accommodative errors in emmetropes and myopes are systematically different, and the effect of using different instruments and metrics. METHODS: Seventy-six adults aged 18-27 years comprising 24 emmetropes (spherical equivalent refraction of the dominant eye +0.04 ± 0.03 D) and 52 myopes (-2.73 ± 0.22 D) were included. Accommodation responses were measured with a Grand Seiko WAM-5500 and a Hartmann-Shack Complete Ophthalmic Analysis System aberrometer, using pupil plane (Zernike and Seidel refraction) and retinal image plane (neural sharpness-NS; and visual Strehl ratio for modulation transfer function-VSMTF) metrics at 40, 33 and 25 cm. Accommodation stimuli were presented to the corrected dominant eye, and responses, referenced to the corneal plane, were determined in the fellow eye. Linear mixed-effects models were used to determine influence of the refractive group, the measurement method, accommodation stimulus, age, race, parental myopia, gender and binocular measures of heterophoria, accommodative convergence/accommodation and convergence accommodation/convergence ratios. RESULTS: Lags of accommodation were affected significantly by the measurement method (p < 0.001), the refractive group (p = 0.003), near heterophoria (p = 0.002) and accommodative stimulus (p < 0.05), with significant interactions between some of these variables. Overall, emmetropes had smaller lags of accommodation than myopes with respective means ± standard errors of 0.31 ± 0.08 D and 0.61 ± 0.06 D (p = 0.003). Lags were largest for the Grand Seiko and Zernike defocus, intermediate for NS and VSMTF, and least for Seidel defocus. CONCLUSIONS: The mean lag of accommodation in emmetropes is approximately equal to the previously reported depth of focus. Myopes had larger (double) lags than emmetropes. Differences between methods and instruments could be as great as 0.50 D, and this must be considered when comparing studies and outcomes. Accommodative lag increased with the accommodation stimulus, but only for methods using a fixed small pupil diameter.

The Effect of Vertically Yoked Prisms on Binocular Vision and Accommodation.

SIGNIFICANCE: Vertically yoked prisms have been used in treatment of binocular vision dysfunction despite minimal supporting evidence. In people with normal binocular vision, the impact on phorias has been assessed but not the impact on accommodation, accommodation vergence interactions, or the horopter. We found that vertically yoked prisms have minor effects during short-term wear in young adults. PURPOSE: The purpose of this study was to determine effects of vertically yoked prisms on accommodative response and several binocular vision tasks. METHODS: There were 45 participants aged 18 to 24 years. The 23 myopes wore distance-corrected soft contact lenses. In a random arrangement, each person wore spectacles containing planopower lenses with either 8 Δ base-up, 4 Δ base-up, zero, 4 Δ base-down, and 8 Δ base-down prisms. Before spectacle wear, baseline measurements of near heterophoria, accommodation response, negative and positive relative accommodations, fusional vergence, and Nonius-horopter spatial perception were taken. Measurements were repeated after a 40-minute wear, spectacles were removed, and tests were performed 20 minutes later. On a 22-participant subset, on a separate occasion, measurements of heterophoria, accommodation response, and relative accommodation were made immediately after spectacles were fitted. RESULTS: Most changes relative to baseline were not significant. Where effects occurred, these were nearly all associated with prism presence rather than adaptation. There were significant effects on accommodation response, but these seem to be refraction effects produced by pantoscopic tilt-induced power changes rather than perceptual effects altering accommodation. There were statistically significant effects on negative relative accommodation (P < .01), with zero prism giving more negative relative accommodation than 8 Δ base-down prisms. Tendencies were noted for prisms to move horopter limits toward the observer. Effects were small and likely not of clinical relevance. CONCLUSIONS: Vertically yoked prisms have minor effects on accommodation and binocular vision, at least during short-term wear in young adults with normal binocular vision.

Effect of spectacle lenses designed to reduce relative peripheral hyperopia on myopia progression in Japanese children: a 2-year multicenter randomized controlled trial.

PURPOSE: Novel spectacle lenses (MyoVision, Carl Zeiss) designed to reduce relative peripheral hyperopia have been developed and reported to be effective for preventing myopia progression in a subgroup of Chinese children. In this study we examined the efficacy of MyoVision lenses in Japanese children. STUDY DESIGN: This was a multicenter prospective randomized double-blind placebo-controlled trial. METHOD: We enrolled 207 participants (aged 6-12 years) with spherical equivalent refractions (SERs) ranging from -1.5 to -4.5 diopters (D) and with at least 1 myopic parent. The participants were randomized to receive either single vision lenses (SVLs) or MyoVision lenses and were followed up every 6 months for 2 years. The primary outcome was myopia progression evaluated by cycloplegic autorefraction, and the secondary outcome was elongation of axial length. RESULTS: A total of 203 children (98.1%) completed the follow-up. The mean adjusted change in SER was -1.43 ± 0.10 D in the MyoVision group, which was not significantly different from that of the control group wearing SVLs (-1.39 ± 0.07 D) at the 24-month visit (P = .65). The adjusted axial length elongation was 0.73 ± 0.04 mm in the MyoVision group, which was not significantly different from that in the control group wearing SVLs (0.69 ± 0.03 mm) at the 24-month visit (P = .28). CONCLUSION: The results of this clinical trial could not verify the therapeutic effect of MyoVision for slowing down myopia progression in Japanese children. Additional studies are needed to design lenses that can reduce peripheral hyperopic defocus individually and to examine the effectiveness of these lenses in preventing myopia progression.

Peripheral Design of Progressive Addition Lenses and the Lag of Accommodation in Myopes.

Purpose: Insufficient accommodative response is assumed to result in myopia progression. We have investigated if the accommodative lag in myopes is different between a single vision lens (SVL) and the progressive addition lens PAL 2, clinically trialled for its ability to reduce progression of myopia, and if there exist differences in accommodative lag between PAL 2 and other PALs with the same addition power (+1.50 D). Methods: The influence of spherical SVL and four different designs of PALs that differ in the near zone width (PAL 1) or that have different signs and magnitude of horizontal gradients of mean power adjacent to their near vision zones (PAL 3 and PAL 4) on the accommodative response was investigated for different near viewing distances (40, 33, and 25 cm) in 31 subjects, aged 18 to 25 years. Results: The SVL correction resulted in insufficient accommodative response for the near object viewing distances tested. PAL 2 did significantly reduce accommodative lag for all near object distances tested. The PAL design with a more negative horizontal mean power gradient (PAL 4) provided a lower lag of accommodation when compared with PAL 2 at the shortest object distance of 25 cm (P = 0.03) and was able to reduce the lag of accommodation to a level below the depth of focus for the higher near working distances tested. Conclusions: Designs of PAL with more negative horizontal mean power gradients are the most effective in lowering the lag of accommodation in myopes. This could make them good test candidates for myopia control applications.

Accommodation stimulus and response determinations with autorefractors.

PURPOSE: To develop equations for accommodation stimulus and accommodation response with autorefractors when the accommodation stimulus is produced by combinations of object distances and lenses placed in front of eyes, and to give worked examples using these equations. METHODS: Simple ray tracing was used to determine stimulus and response equations, taking into account the reference positions for targets, for refraction, and for autorefractor readings. RESULTS: Several examples applying equations are provided. Features of these examples include evaluating approximate calculations that have been used previously, demonstrating which equations should be used in different circumstances, how to substitute numbers into equations, how to deal with discrepancies between subjective and objective refraction, and how to deal with astigmatism. Problems associated with measuring accommodation response by placing lenses in front of the eye are discussed. CONCLUSIONS: Accurate equations for accommodation stimulus and accommodation response for a range of accommodation stimuli in different setups have been developed.

Myopia control with positively aspherized progressive addition lenses: a 2-year, multicenter, randomized, controlled trial.

PURPOSE: To evaluate the effect of newly designed positively aspherized progressive addition lenses (PA-PALs), which reduce both lag of accommodation and hyperopic defocus on the peripheral retina, on the progression of early-onset myopia. METHODS: Positively aspherized-PALs have near addition and high positive distance zone aspherization comparable to the addition power. One hundred ninety-seven children were enrolled, 6 to 12 years of age, with spherical equivalent refraction from -1.00 to -4.50 diopters (D). The children were randomized to receive one of three lenses: single vision lenses (SVLs), PA-PALs with +1.0 D addition, or PA-PALs with +1.5 D addition. Follow-up visits occurred every 6 months for 2 years. The primary outcome was myopia progression evaluated by cycloplegic autorefraction. RESULTS: One hundred sixty-nine (86%) children completed the follow-up. Statistical analysis of adjusted progression rates showed a mean (±SE) progression of -1.39 ± 0.09 D in the control group wearing SVLs at the 24-month visit. Statistically significant (P = 0.017) retardation of myopia progression (0.27 ± 0.11 D during 24-month period or reduction ratio of 20%) by +1.5 D add PA-PALs relative to the SVLs was found, which was within the range of the percentage efficacy of myopia retardation by the conventional PALs in earlier trials over the same follow-up period. Nearly all retardation occurred in the first 12 months with no significant efficacy in the second year. Positively aspherized-PALs with +1.0 D addition showed negligible efficacy. CONCLUSIONS: To the extent that has been tested and that can be tolerated by wearers of spectacle lenses, the high positive aspherization of the distance zone added to PALs does not enhance their therapeutic efficacy in slowing myopia progression. (http://www.anzctr.org.au/ number, ACTRN12608000566336).

Visual performance with lenses correcting peripheral refractive errors.

PURPOSE: To design and manufacture lenses to correct peripheral refraction along the horizontal meridian and to determine whether these resulted in noticeable improvements in visual performance. METHODS: Subjective refraction of a low myope was determined on the basis of best peripheral detection acuity along the horizontal visual field out to ±30° for both horizontal and vertical gratings. Subjective refraction was compared to objective refractions using a COAS-HD aberrometer. Special lenses were made to correct peripheral refraction, based on designs optimized with and without smoothing across a 3-mm diameter square aperture. Grating detection was retested with these lenses. Contrast thresholds of 1.25-min arc spots were determined across the field for the conditions of best correction, on-axis correction, and the special lenses. RESULTS: The participant had high relative peripheral hyperopia, particularly in the temporal visual field (maximum, 2.9 D). There were differences >0.5 D between subjective and objective refractions at a few field angles. On-axis correction reduced peripheral detection acuity and increased peripheral contrast threshold in the peripheral visual field, relative to the best correction, by up to 0.4 and 0.5 log units, respectively. The special lenses restored most of the peripheral vision, although not all at angles to ±10°, and with the lens optimized with aperture smoothing possibly giving better vision than the lens optimized without aperture smoothing at some angles. CONCLUSIONS: It is possible to design and manufacture lenses to give near-optimum peripheral visual performance to at least ±30° along one visual field meridian. The benefit of such lenses is likely to be manifest only if a subject has a considerable relative peripheral refraction, for example, of the order of 2 D.