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Percy Lazon De La Jara, Fabian Conrad, Padmaja R. Sankaridurg, Darrin Falk, Arthur Ho; Influence of Contact Lens-Induced Optical Defocus on Peripheral Visual Acuity and Contrast Sensitivity. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1901. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the influence of defocus induced by soft contact lenses (SCL) on contrast sensitivity (PCS) and visual acuity (PVA) in the peripheral visual field.
Two novel designs of SCL (Lotrafilcon B, CIBA Vision, USA) were tested: a higher (HD) and a lower (LD) design that introduce positive peripheral powers relative to on-axis power. Myopic participants wore the HD SCL with a relative peripheral power of +7.50D (n=14) and the LD SCL with a relative peripheral power of +4.00D (n=13). All participants wore a commercially-available single vision SCL (Lotrafilcon B, CIBA VISION, USA) as a control. Central and peripheral refraction were measured using a modified Shin-Nippon NVision K5001 autorefractor. PCS and PVA were assessed at the 30° temporal (TF) and nasal (NF) visual field using a computer-based test; sinusoidal gradation annuli of 2 cycles per degree for PCS (tandem pairs); Landolt C for PVA; both stimuli were presented tachistoscopically (200 ms) and a staircase procedure (1-up-3-down) was used to determine threshold. Paired t-tests were used to test for differences between lenses and retinal visual fields.
Both novel SCLs showed a significant increase in relative myopic defocus at the NF and TF at 30° field compared to the control (p<0.05). There was nasal-temporal asymmetry, the induced myopic defocus (M) being greater in the NF (LD -2.25±2.00D, HD -3.85±1.23D) than the TF (LD -0.45±1.01D, HD -1.13±1.18D). The nasal retina (TF) has greater PCS irrespective of which lens was worn (p<0.05), however for PVA this effect was not observed with the novel lenses. Compared to the control, the HD design decreased PCS in both peripheral locations (p<0.05) whereas PVA was not affected in NF and the LD design decreased PCS only in the nasal field, PCS in the temporal field and PVA remained unaffected (p>0.05).
PCS is sensitive to peripheral defocus induced by SCL. To a lesser extent, PVA in the TF is also influenced by SCL-induced defocus. In agreement with previous findings, the nasal retina has greater PCS than the temporal retina. The refractive status at 30° field influences peripheral visual performance.
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