|
KMID : 1011420170220020167
|
|
Journal of Korean Ophthalmic Optics Society
2017 Volume.22 No. 2 p.167 ~ p.173
|
|
|
Influence of Dissociating Prism on Lateral Phoria in Von Graefe Test
|
|
Oh Kwang-Keun
Cho Hyun-Gug
Moon Byeong-Yeon
Kim Sang-Yeob
Yu Dong-Sik
|
|
|
Abstract
|
|
|
Purpose: To evaluate the influence of the amount of prism diopters for dissociating prism on lateral phoria in von Graefe test.
Methods: Forty subjects (mean age 22.10±2.24 years) were conducted subjective refraction and phoria test. Lateral phoria using the von Graefe method was measured with measuring prism of 12 Δ base-in (BI) in front of right eye and dissociating prisms of 0, 2, 4, 6, 8 and 10 Δ base-up (BU) in front of left eye respectively, selected in random order. The influence of the dissociating prism was analyzed according to vertical phoria and cyclophoria groups.
Results: The amount of prism to dissociate targets for phoria test was greater than or equal to 6 Δ BU at both distance and near. Lateral phoria was significantly decreased with increasing the amount of dissociating prism at distance (0.37?0.88 Δ decrease in exophoria, p<0.001), but no significant at near (p = 0.793). In left hyperphoria group at distance, lateral phoria was decreased (0.19?0.91 Δ decrease in exophoria, p = 0.038) with increasing the dissociating prism, but no statistical significant change in left hypophoria and orthophoria group at distance, and in all groups at near. In cyclophoria and non-cyclophoria group, distance lateral phoria was decreased with increase of the dissociating prism (0.33?1.02 Δ in exophoria, p = 0.001; 0.40?0.80 Δ in exophoria, p = 0.014), but not significantly changes in all groups at near.
Conclusions: The amount of dissociating prism in von Graefe test has an influence on distance lateral phoria. The influence was better represented when the prism is placed on side of hyperphoria or cyclophoria. With a vertical phoria or a cyclophoria, lateral phoria could be different depending on the placement of dissociating prism. To improve the reliability of the von Graefe, we suggest that the dissociating prism of BU is placed in the front of eye with hypophoria or vertical prism has to compensate before lateral phoria test.
|
|
|
KEYWORD
|
|
|
Phoria, Lateral phoria, Vertical phoria, Cyclophoria, Dissociating prism, Von Graefe, Exophoria
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|