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Nadine Solaka, Hilary Gaiser, Joshua Silver, Bruce Moore; Assessing the Quality of Functional Vision through AdSpecs.. Invest. Ophthalmol. Vis. Sci. 2013;54(15):580. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
According to the RESC Studies, at least 10% of children in the developing world could benefit from refractive correction. Lack of professional eyecare limits access to refractive correction. Adjustable glasses (AdSpecs) both measure and correct refractive error. A previously published study showed that AdSpecs provide clear vision when adjusted by myopic children. However, it remained uncertain whether this complex lens system may adversely effect visual function, especially at near. The purpose of this study was to assess near visual function through AdSpecs.
30 myopic adults 21-41 years of age were recruited from New England College of Optometry. Near VA was measured in M-units using a Good-Lite (#251000) near card at 40 cm. Contrast sensitivity (CS) was measured using a Mars Test (mars perceptrix) at 50 cm. Lateral and vertical phoria were measured with Modified Thorington at 40 cm. All tests were done in down gaze (45° from primary gaze) with both AdSpecs and habitual correction (HC). Inclusion criteria were: Hyperopia +1.50 to +4.50 D, Myopia -0.75 to -6.00 D, Astigmatism <2.00 D, Anisometropia <1.00 D and VAcc ≥20/25 in each eye.
Near VA mean for OD was 1.08M ± 0.16M with HC and 0.99M ± 0.20M with AdSpecs (mean diff.: 0.09M, p-value: 0.02). CS mean for OD was 1.76 ±0.07 with HC and 1.77 ±0.05 with AdSpecs (mean diff.: -0.01, p-value: 0.62). Lateral phoria mean was -3.57PD (Exo) ±4.74PD with HC and -3.48PD (Exo) ±5.15PD with AdSpecs (mean diff.: -0.09PD (Exo), p-value: 0.79). Vertical phoria mean was 0.02PD (RHyper) ±0.43PD with HC and -0.08PD (RHypo) ±0.47PD with AdSpecs (mean diff.: 0.1PD (RHyper), p-value: 0.25).
Near VA was slightly reduced through AdSpecs. This may be due to the AdSpec's complex lens design. Multiple lens surfaces result in reflection and reduced light transmission. CS and phoria were similar between AdSpecs and HC . The small difference in phoria is likely due to the preset pupillary distance on the AdSpecs, resulting in some subjects with induced prismatic effect exacerbated by the complex lens system. Future designs with reduced lens thickness are underway. Despite small statistical differences, the overall results of each of the variables (near VA, contrast sensitivity and phoria) were not clinically significantly different between the AdSpecs and HC. These results help answer the question about the quality of functional vision through these adjustable glasses.
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