|
KMID : 1159320190210020181
|
|
Korean Journal of Vision Science
2019 Volume.21 No. 2 p.181 ~ p.191
|
|
|
Change in Refractive Power When Viewing through the Periphery of Plus Lens
|
|
Sa Jong-Hwan
Yu Dong-Sik
Cho Hyun-Gug
Kim Sang-Yeob
Moon Byeong-Yeon
|
|
|
Abstract
|
|
|
Purpose : The aim of this study was to investigate the changes of refractive power when an eye looks through periphery of a spectacle plus lens with gaze angles.
Methods : In order to measure the changes in refraction when viewing through the periphery of the plus lens with a gaze angle, the refractive power was measured using digital lensmeter while the optical axis of lens was tilted by gaze angle around a pivot which was placed 25 mm below from lens support of lensmeter. The effects on the refraction caused by changes of lens thickness and vertex distance with increase of gaze angle were also examined.
Results : The thickness of plus lens was decreased and vertex distance was increased rapidly according to increase of gaze angle. The change in correction power by the varied thickness was less than 0.03 D and was negligible in refractive effect when +6.00 D lens was used with 30? gaze angle. As the gaze angle increases, the vertex distance became longer, and the (+) refractive power should be reduced so that the overcorrection does not occur. However, the measured refractive power tended to increase and for glasses wearer, the refractive power may be shown a weighted effect. The most significant effect was the change in refractive power due to astigmatism. It is thought that the wearer will feel discomfort due to the increase of the minimum refractive power and the cylindrical power at the gaze angle of 15? or more.
Conclusion : The changes in refraction due to vertex distance and cylindrical power due to astigmatism should be considered when using peripheral area of spectacle lenses. Fitting process of face form angle can be helpful to reduce the perceptual changes when looking through peripheral area of lens.
|
|
|
KEYWORD
|
|
|
Astigmatism, Gaze angle, Refractive power, Thickness of lens, Vertex distance
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|