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简介 j_?cpm{~ml t0PQ~|H<KV 人眼光学模型可用来设计眼科用设备,光学系统注定了要与人眼一起使用。本文演示了这样一个模型:Arizona眼睛模型,在Jim Schwiegerling教授的书中有详细描述:《Field Guide to Visual and Ophthalmic Optics》。AZ眼睛模型达到了基于平均临床数据所决定的轴上和轴外像差等级。FRED文件包含了此眼睛模型及几个用来分析它的光源,并包括一个基于想要的屈光度来调整模型的内嵌脚本。 HW=xvA+ V'Y{v 模型 )Du-_Z ;i#LIHJ 模型的定义如表1种所示,由半径、圆锥常数、折射率、阿贝数、到下一面的距离等一系列表面组成。一些参数由屈光度(A)来决定。 go)p%}s juToO Table 1. AZ眼睛模型的定义 MBk"KF 在FRED中使用0屈光度来创建的,光瞳加在了透镜的前面。材料是创建一个新的材料并选择类型“Model Material”,输入的参数是nd和vd. nN`"z3o 7x.%hRk 光源 @kngI7=E r
-f 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 >3;^l/2c h"QbA" FN"rZWM 图1. 光源和提示信息使用 5!fSW2N 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 RagiV6c 67<CbQZoN3 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 n~z\?Y=* 4".J/I5u 图2. 字母F光源的设定方法光 #dJ 2Q_2 #t71U a 图3. 字母F在视网膜上位置点列图 `]2@_wa 视网膜的散射 [J\DB)V/ >.dHt\ 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 7{BnXN[ L@|#Bbmx \ 3NS>v[1 图4. 视网膜朗伯散射设定 MUof=EJg>u 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 \v`#|lT$ ;R1B9-, O4+F^+qN 图5. 视网膜重点采样规格设定 =mrY/:V 脚本 9EgP9up{6! uIP
iM8( 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: &zN@5m$k; q@ Kk\m 图6. 用户对话框的创建与编辑 j8HOc( 图7. 用户对话框编辑器 GfsBQY/ 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 n! .2aq 余下的脚本计算与屈光度有关的所有参数。 nTZ> |R) k8&FDz 分析 Vq}r_#!Q Z*bC#s? 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 (L#%!bd \.>.c g 图7. 字母F在视网膜上颜色分析 $v&C@l \ 脚本代码 *C_[jk@6 ^pcRW44K Option Explicit 'Remove this to enable non-dimensioned variables to be used. ?vu|o'$T, Zd<[=%d Dim entity As T_ENTITY nUqy1( Dim op As T_OPERATION VN|G5* Dim mat As T_MODELMATERIAL ]V<"(?,K Dim A As Double B
T7Id Dim pupilDiam As Double hPPB45^ Dim eID As Long V<-htV Dim parID As Long ;QidDi_s> Dim count As Integer ;5M<j3_* Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double A7'b Nd6f9 Dim tlens As Double, nlens As Double "-U3=+ Dim curv As Double, conic As Double ]31$KBC Dim ok As Long >-<F) Ygx,t|?7 Sub Main }N| \ oWD)+5.] '用户输入对话框 !Zj#.6c9 Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 6K//1U$ TextBox 220,21,40,21,.TextBox1 'default: 0 YKq0f=Ij Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 %]GV+!3S OKButton 40,91,90,21 ('HxHOh2 CancelButton 190,91,90,21 ;.0LRWcJ Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 q2Rf@nt TextBox 220,49,40,21,.TextBox2 'default: 4 =~",/I? End Dialog a>(~ C'(< Dim dlg As UserDialog BvI 0v: QRagz,c ok = Dialog (dlg) 'fl(N2t 28+HKbgK If ok=0 Then 'cancel button was pressed &E]"c]i+ Print "Execution cancelled." Bt6xV<jD End EOQaY End If ~*kK4]lP +{0=<2(EC 'Assign accommodation and pupil diameter & use defaults if field left empty =SL^>HS.fo If dlg.TextBox1 = "" Then I}ndRDz[ A = 0 'Default accommodation Cg*kN"8q Else }6@%((9E2 A = CDbl(dlg.TextBox1) (k#t}B[ End If %Y 2G D9G0k[D, If dlg.TextBox2 = "" Then n531rkK- pupilDiam = 4 'Default pupil diameter (ic@3:xR Else 5E.vje{U; pupilDiam = CDbl(dlg.TextBox2) Q6|@N~UeZ End If q!@c_o X$ PS(_M Print " " ]eD [4Y\#t Print "Accommodation = " & A & " Diopters"
\aB&{`iG Print "Pupil Diameter = " & pupilDiam & " mm" ja:\W\xhJ YOlH*cZtg ' Calculate new parameters with accommodation v<`$bvv? taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness 3m~U(yho P8u"T!G Rant = 12.0 - 0.4*A 'Radius of anterior lens BMF3XcH~G CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens r=|vad$ s1v{~xP Rpost = -5.224557 + 0.2*A 'Radius of posterior lens }R\B.2#M_@ CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens ~"\P~cg0J ]svw
CPu C tlens = 3.767 + 0.04*A 'Lens thickness Hj1k-Bs&'w ~(M*6b nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction 78gob&p? BHIM'24bp 'Adjust parameters to account for accommodation )biX8yqhR P0Aas)! '************************************************************************* '2j~WUEmg 'Aqueous thickness (Position of Lens) cUYX1a)8 '************************************************************************* z^"?sd eID = FindFullName( "Geometry.Arizona Eye.Lens" ) Km%8Yw0+ GetCustomElement eID, entity ayN*fiV] vDWr|M%``l parID = FindFullName( "Geometry.Arizona Eye" ) )~G8 L Z hg!x_Eq| ' Delete any shift(s) in z miWw6!() count = 0 5,Qy/t}K While GetOperationCount(eID)>count :E}6S GetOperation eID, count, op P%ye$SASd If op.Type="ShiftZ" Then
hgNY[, DeleteOperation eID,count e-1;dX HL count=count-1 z)r8?9u End If wX@H
&)<s count=count+1 _8Pmv$ Wend ?#x'_2 `AB~YX%( 'Set new shift in 5X#i65_- op.Type = "ShiftZ" hwc:@' op.val1 = taq 8U8P
g2 op.parent = parID .Ydr[ AddOperation eID, op oXvdR(Sb^ Print "Set aqueous humor thickness = " & taq-0.55 8a_ UxB ~>lOl/n 5 '************************************************************************* f;&` 9s| 1 'Radius and conic constant of anterior lens }3LBbG0Bw '************************************************************************* Fa6H(L3 eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) r{bgTG GetConic eID, entity, curv, conic '3IkPy1Uz $b&BH'*'~ SetConic eID, entity, 1/Rant, CCant &IIJKn|_ Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant VZAuUw+M x;<oaT$X '************************************************************************* f6@^Mg 'Radius and conic constant of posterior lens IY-(-
a8 '************************************************************************* dw@TbJ eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) h2im
sjf GetConic eID, entity, curv, conic >aNbp Cmp{F N"o SetConic eID, entity, 1/Rpost, CCpost ~5x4?2 Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost {Q}!NkF1 OaX HJ^k '************************************************************************* #JHy[!4 'Lens thickness (Position of posterior lens surface) IptB.bYc '************************************************************************* V.O<|tl. u<BHf@AI parID = FindFullName( "Geometry.Arizona Eye.Lens" ) $w 5#2Za V,99N'o~x ' Delete any z-shift(s) "H
wVK count = 0 ,<R>Hiwg/s While GetOperationCount(eID)>count |?4~T: GetOperation eID, count, op Nv}U/$$S If op.Type="ShiftZ" Then Uqb]e?@ DeleteOperation eID,count P]~N-xdV count=count-1 Z1XUYe62 End If (CKhY~,/u count=count+1 *
ePDc' Wend G~b`O20N :mCw.Jz<h 'Set new z-shift 5?#OR!N op.Type = "ShiftZ" FU [8:o62 op.val1 = tlens # CP9^R S op.parent = parID lq7 8gOg{ AddOperation eID, op bn^mL~ Print "Set lens thickness = " & tlens x9FLr}e uOivnJ? '************************************************************************* <-Kb@V3 'Lens index of refraction y@2vY[)3s '************************************************************************* &etL&s v eID = FindMaterial( "Lens" ) e
_SoM!; GetModelMaterial eID, mat %RfY`n llTQ\7zP mat.Nd = nlens VuJfo9 `E SetModelMaterial eID, mat 1Ovx$* Print "Set lens index of refraction = " & nlens tkm~KLWV&7 B` t6H '************************************************************************* wI1M0@}PV 'Pupil diameter 8.q13t!D '************************************************************************* , u8ZS|9 eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) xr7-[)3Q$ : pE-{3I 'Adjust pupil diameter (trimming volume inner hole) "G i+zkVm JN;TGtB^p SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" U#UVenp@ .&*
({UM ' Adjust pupil location to just in front of the lens ArEH%e parID = FindFullName( "Geometry.Arizona Eye" ) X$j|/)) eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) n;S0fg count = 0
Xv?
S While GetOperationCount(eID)>count gnKU\>2k GetOperation eID, count, op O|^6UH If op.Type="ShiftZ" Then @@&@}IQcR1 DeleteOperation eID,count On2Vf*G@| count=count-1 <.?^LT End If H$=h- count=count+1 C[J`x>-K Wend O;&yA< op.Type = "ShiftZ" i no7!T` op.val1 = taq-0.01 o%N0K op.parent = parID gOES2
4$2 AddOperation eID, op ]6i_d YDZ1@N}^B Print "Set pupil diameter = " & pupilDiam m\}\RnZu |RvpEy76 'Update AZ Eye subassembly Description fd,}YAiX eID = FindFullName( "Geometry.Arizona Eye" ) ;k63RNT,M& GetEntity eID, entity e5"-4udCn entity.Description = "Accommodation = " & A & "D" $J;=Ux)$ SetEntity eID, entity vt(}ga >m;|I/2@ Update Ekg N6S`} Print "DONE!" Rm[rQ}: ,Rr&. End Sub b/D9P~cE ~;O=
7 如果屈光度是4,光瞳直径是4,则会输出如下数据: :+Z>nHe ;03*qOYc Accommodation = 4 Diopters =%nqMV(y Pupil Diameter = 4 mm EiIFVP Set aqueous humor thickness = 2.81 ;>QK}#' Set anterior lens radius = 10.4 and conic constant = -2.375869 Lu#@~ Set posterior lens radius = -4.424557 and conic constant = -3.081019 m?kIa!GM= Set lens thickness = 3.927 lG[
)8!:+ Set lens index of refraction = 1.42672 Um0<I) Set pupil diameter = 4 vI:bl~ DONE! H?/cG_^y0 H $qdU!c 6Kv}2M')+ QQ:2987619807 &oK/]lub
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