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KMID : 1011420190240020109
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Journal of Korean Ophthalmic Optics Society
2019 Volume.24 No. 2 p.109 ~ p.115
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Effect of Soft Contact Lenses with a Hydrophilic Polymer on the Contrast Sensitivity Function
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Yun Kyung-Hee
Lee Jae-Chol
Seo Jae-Myoung
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Abstract
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Purpose: It is investigated whether the contrast sensitivity (CS) after wearing soft contact lenses (SCLs) is improved by the interpenetrating polymer networks (IPN) of polyvinylpyrrolidone (PVP) and polyethylene glycol (PEC).
Methods: Twenty subjects participated in the study to determine the average CS thresholds for SCLs with PVP K90 0.3% and for SCLs without PVP for comparison. The CS thresholds after the subjects wore the two different types of SCLs were measured for two different forced choice stair cases of 3 and 18 cycles per degree (cpd) static sinusoidal gratings for 88 ms and 518 ms within a circular aperture using the software program MorphonomeTM. The results were analyzed by Pearson correlation and a paired T-test.
Results: The group wearing the SCLs with PVP had an improved CS overall for 3 cpd compared with the group without the PVP. In particular, the contrast thresholds for 88 ms and 518 ms were 0.2 and 0.41 lower after 12h of wearing SCLs, respectively, which showed that the SCLs with PVP enhanced the CS despite the extended wearing time. However, the CS for 18 cpd varied according to the target exposure times. The experimental group had an improved CS for 88 ms, which was not significant, whereas the contrast threshold for 518 ms increased with wearing time 4h, 8h and 12 hours (1.02, 0.67 and 1.24, respectively).
Conclusions: The IPN technique with PVP improved the CS. However, the measurement of CS for higher spatial frequencies has to be taken into consideration.
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KEYWORD
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Hydrophilic polymer, Contact lens, Contrast sensitivity function, Contrast threshold, Spatial frequency, Interpenetrating polymer networks
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