單眼低度未矯正散光對雙眼視覺的影響

一般在低度散光要配眼鏡或隱形眼鏡時，有時會用等值球面來配。
也就是散光不配，並將散光的一半加到球面度
例如，近視-1.00D散光-0.50D，就配近視-1.25D


以下論文討論當單眼採此種配法時對雙眼視覺的影響
結果是並不會有影響。
http://www.ncbi.nlm.nih.gov/pubmed/22107117


當單眼採用此配法時，視力將較為模糊
1D的未矯正散光將使視力從6/6(1.0)降到6/8(0.67)
此研究設計將已矯正患者戴上散光試鏡架，模擬出-0.75D 與 -1.25D 在 90度與45度軸
測量雙眼的固視偏差(兩眼同視時的偏差)，結果並無明顯差異。
這可以提供在低度散光配隱形眼鏡時的參考。


但這邊我有一點問題是為何不選擇一般人常見的散光軸180度?
再來雖然對雙眼視覺的影響不大，但對視力的影響就要看個人情況了。

Strabismus. 2011 Dec;19(4):138-41.

The influence of unilateral uncorrected astigmatism on binocular vision and fixation disparity.

Nilsson A, Nilsson M, Stevenson SB, Brautaset RL.

Source

Unit of Optometry, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden.

Abstract

Purpose: It is accepted practice to use a spherical equivalent power as an alternative contact lens correction for those patients with lower amounts of astigmatism, allowing for an easier fit, but the blur caused by one diopter of uncorrected astigmatism can reduce acuity of 6/6 to that of about 6/8. This is usually deemed acceptable monocularly, often retaining a good binocular acuity. The purpose of this study is to explore how monocular astigmatic blur may also affect the patient's binocular vision function. Methods: A trial frame was outfitted with full correction for 20 healthy subjects (mean age 25.5 years, range 19-36 years) and a baseline horizontal fixation disparity was measured at a distance of 1 m. Thereafter, fixation disparity was measured with induced monocular astigmatic blur in the right eye, creating an astigmatic error in the amounts of -0.75 and -1.25 in axis 90 and axis 45. Results: It was determined that the differences among full correction and the 4 different types of astigmatic blur were not significant when analyzed as one group (P = 0.5445), nor when separated into groups according to whether the subject had naturally occurring astigmatism or not, (astigmatic group, P = 0.3801; non-astigmatic group, P = 0.5899). Conclusions: Monocular astigmatic blur in the amounts of -0.75 and -1.25 did not have a significant effect on tested subjects with regard to the amount of blur or axis orientation. This low amount of blur is likely within the range of compensation for the subjects, proving that spherical equivalent contact lenses are a viable option for low amounts of astigmatic error.

PMID:

 

22107117

 

[PubMed - in process]