對於無斜視患者的稜鏡加入建議量 - 眼鏡

本篇文章用模形式推導說明:

(1)morgan與oep之相關異向補償融像運動極值測試數據，

遠用內集情況之模糊點為accomodation limit模糊狀態；

　 近用內集,遠用外散,近用外散情況之模糊點為vergence limit模糊狀態；


(2)Cmax < 25.5Δ #測量值為36Δ(morgan系統)，
Cmax < 22.2Δ #測量值為31.7Δ(OEP系統)
Cmin > -4.5Δ #測量值-6.4Δ (morgan系統)，
Cmin > -5.9Δ~-6.74Δ #測量值為-8.4Δ~-9.6Δ(OEP系統)


(3)sheard criterion和percival criterion必須在單眼mpmva處方下進行才有意義


(4)在遠用處方下，sheard criterion和percival criterion建議量值一致

兩者為等效準則..


(5)在近用處方下，對於外斜患者斜位量修正建議量

sheard criterion建議量 > percival criterion建議量

差異約 {0.5Δ+ [(6-A)/3]*(1/工作距離)}


(6)在近用處方下，對於內斜患者斜位量修正建議量

　 sheard criterion建議量 < percival criterion建議量

差異約 {- 0.5Δ- [(6-A)/3]*(1/工作距離)}


以上近用條件為工作距離設定為 16 inch

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相關實驗數據論文連結:http://www.opt.indiana.edu/IndJOpt/ijofall05.pdf

論文名稱:Comparison of Methods of Prescribing Lateral Prism Power in
Non-Strabismic Subjects

作者:David A. Goss, O.D., Ph.D.


摘錄:

Sheard's criterion and Percival's criterion results were also quite closely
related in this study.

Sheard's criterion, based on the dissociated phoria and the compensating
vergence, often yields more prism in symptomatic individuals with exophoria
than Percival's criterion, which is based on the balance between the vergences.

Percival's criterion often suggests more prism in symptomatic individuals
with esophoria than Sheard's criterion.


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Sheard criterion (外斜)

P = (2D - R) / 3

D = the magnitude of the dissociated phoria,

R = the base-in blur (break if no blur occurred) inesophoria
or the base-out blur (break if no blur) inexophoria,

P = Sheard's criterion prismamount.

A negative P value, indicating that Sheard's criterion was met, was included
in thedata analysis as a zero value because no prismwould be recommended
.
單眼所需稜鏡度 = (2/3) *斜位 – (1/3)單眼相關補償融像異向運動



example: pat 10 base out exo tropia，異向運動 12BO

需矯正量為 P = (2/3)*10 – (1/3)*12 = 2.64 (BI)

#此例子只是方便理解，並不代表此例子合乎實際

=========================================================================
Percival criterion (外斜)

P = (G - 2L) / 3

G = the greater of the two lateral fusional vergence limits (base-in or
base-out),

L = the lesser of the fusional vergence limits,

P = Percival's criterion prism amount.

A negative Pvalue, indicating that Percival's criterion was met,was considered
to be a zero value for analysisbecause no prism would be recommended..

單眼所需稜鏡度 = (1/3)較大單眼補償融像異向運動 – (2/3)較小單眼補償融像異向運動




example: pat ，異向運動 12BO,5BI

需矯正量為 P = (1/3)*12 – (2/3)*5 = 2 (BO)

#此例子只是方便理解，並不代表此例子合乎實際

==============================================================================

證明：

採用morgan與oep實驗數據，模型式推導出(1)與(2)
http://www.wretch.cc/blog/kramnik1/13654279


用模型式可以輕易推導出在雙眼mpmva情況下，
再使用稜鏡加入建議量公式是無意義的，推導出(3) #略


以上述推導結果為根基，可進一步推導出(4)
http://www.wretch.cc/blog/kramnik1/13674852


對於近用處方，可以推導出(5)與(6)
http://www.wretch.cc/blog/kramnik1/13674856


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附註:論文連結內文有提到，不論對於外斜還是內斜患者，
　　
大部分的視光師對於sheard criterion比較有信心..


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