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简介 <eG8xC Q[N6# C:(4 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。 HX:rVHY 9hIcnPu 模型 #97w6,P+ ^8r4tX 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。 :3Hr:~ X"qC&oZmf Table 1. AZ眼睛模型的定义 .I&]G 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. 6?v)Hb}J%d i@}/KT 光源
W{2(fb Lg[_9`\ 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。 Z6I^HG{: 3<nd;@:- #(G#O1+ 图1. 光源和提示信息使用
_A %8oYS 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。 REvY`
l|P(S(ikh 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。 H%:~&_D sOBy)vq?\ 图2. 字母F光源的设定方法光 m# ]VdO'f J9
iQ W 图3. 字母F在视网膜上位置点列图 f._FwD 视网膜的散射 ovn)lIs ,U#$Qb 12 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 h)qapC5z, O67.DEu^ ^Pk-<b4} 图4. 视网膜朗伯散射设定 71?>~PnbH} 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 HJ2r~KIw b4$-?f?V H1FSN6' 图5. 视网膜重点采样规格设定 Gdd lB2L)x 脚本 dfBTx6/F ]#N~r&hmQ 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: pZ,P_? Nn],sEs 图6. 用户对话框的创建与编辑 "&ElKy
7j 图7. 用户对话框编辑器 a0oM KGW: 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。 `4'['x 余下的脚本计算与屈光度有关的所有参数。 i#M$i*H*A H *gF>1 分析 csV.AN'obq :b&O{>M]Y 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 B|-E3v:f4 mV0.9pxS 图7. 字母F在视网膜上颜色分析 ^y,%Tv> 脚本代码 j`Xe0U< p<\yp<g Option Explicit 'Remove this to enable non-dimensioned variables to be used. Wv]NFHe# 4A_}:nU Dim entity As T_ENTITY _[8BAm Dim op As T_OPERATION , wT$L3 Dim mat As T_MODELMATERIAL +IiL(\ew Dim A As Double OYEL` !Q Dim pupilDiam As Double *OT6)]|k Dim eID As Long 1YmB2h[Z Dim parID As Long {BBL`tg60 Dim count As Integer vt3yCS Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double 1)8;9
Ba: Dim tlens As Double, nlens As Double Htseu`>_$ Dim curv As Double, conic As Double ,nJYYM
Dim ok As Long g_\U-pzr );*A$C9RA Sub Main ON{&- er Cl@sq '用户输入对话框 jOppru5U Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 "Ldi<xq%xl TextBox 220,21,40,21,.TextBox1 'default: 0 t'bzhPQO)f Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 GVT+c@Gx
OKButton 40,91,90,21 ]~:9b[G2 CancelButton 190,91,90,21 f>Mg.9gJ( Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 DS,"^K TextBox 220,49,40,21,.TextBox2 'default: 4 $2=-Q/lM End Dialog )vB,eZq Dim dlg As UserDialog 8}FZ1h2
4 =IH z@CU ok = Dialog (dlg) m"P"iK/Av( n%lY7.z8d If ok=0 Then 'cancel button was pressed >qj Q;z[ Print "Execution cancelled." Tti]H9g_ End IG?044Y End If Re3vW re vDgf} 'Assign accommodation and pupil diameter & use defaults if field left empty LEoL6ga If dlg.TextBox1 = "" Then __\Tv>Y A = 0 'Default accommodation LHjGlBy Else 6mr5`5~w A = CDbl(dlg.TextBox1) )x1LOMe End If /xmUu0H$R v%|^\A"V If dlg.TextBox2 = "" Then XOQj?Q7)U pupilDiam = 4 'Default pupil diameter &BnK[Q8X Else lLy^@s pupilDiam = CDbl(dlg.TextBox2) c!Gnd*!?- End If u?[dy
n FI1R7A Print " " 2)DrZI Print "Accommodation = " & A & " Diopters" " >QNiR! Print "Pupil Diameter = " & pupilDiam & " mm" JTw\5j KUG\C\z6= ' Calculate new parameters with accommodation Ti`H?9t taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness './j<2|;U !ydJ{\; Rant = 12.0 - 0.4*A 'Radius of anterior lens )v&r^DR_ CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens ob=GB71j55 Np>[mNmga Rpost = -5.224557 + 0.2*A 'Radius of posterior lens , &S:(b[D CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens : E`N0UA <^?64 tlens = 3.767 + 0.04*A 'Lens thickness l?:!G7ie Fw!CssW nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction (J(JB}[X, V
QE *B 'Adjust parameters to account for accommodation >'3J. FY &KC^Vn3Nj '************************************************************************* LyM" 'Aqueous thickness (Position of Lens) qP<wf=wY '************************************************************************* HMbF#!E eID = FindFullName( "Geometry.Arizona Eye.Lens" ) FCv3ZF?K GetCustomElement eID, entity Y_n^6 ; g6:S"Em parID = FindFullName( "Geometry.Arizona Eye" ) 0\f3L a qSh^|;2?R ' Delete any shift(s) in z V3&_ST count = 0 ;C=C`$Q While GetOperationCount(eID)>count hO3>Gl5< GetOperation eID, count, op 1*aw~nY0 If op.Type="ShiftZ" Then @l~zn%!X DeleteOperation eID,count *C*n (the count=count-1 )8Defuxk End If MY11 5% count=count+1 '&{`^l/MH Wend =ja(;uC Id3i qAL 'Set new shift in J8[N!qDCj op.Type = "ShiftZ" ~Aul 7[IH op.val1 = taq /*DC`,q op.parent = parID Tl9KL%9 AddOperation eID, op q1QrtJFPG Print "Set aqueous humor thickness = " & taq-0.55 z>$AZ>t%J$ *I7$\0Q '************************************************************************* A7!!kR": 'Radius and conic constant of anterior lens A;E7~qOG '************************************************************************* _h1n]@
d5 eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) N<V,5 GetConic eID, entity, curv, conic Yhu
6QyRV Ym~*5| SetConic eID, entity, 1/Rant, CCant "I.PV$Rxl Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 5(kRFb'31F hawE2k0p( '************************************************************************* |U}al[ 'Radius and conic constant of posterior lens / 0Z_$Q&e '************************************************************************* A%S6&!I:( eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 4OLq GetConic eID, entity, curv, conic qE73M5L& H2oAek( SetConic eID, entity, 1/Rpost, CCpost ][R#Q;y< Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 3(|8gWQ `* !t<?$i '************************************************************************* alM
^
X 'Lens thickness (Position of posterior lens surface) $agd9z,&m '************************************************************************* -s
Iji)t yeQ6\yi parID = FindFullName( "Geometry.Arizona Eye.Lens" ) 8':^tMd ,1+AfI ' Delete any z-shift(s) u'"VbW3u n count = 0 595P04 While GetOperationCount(eID)>count |1vikG8 GetOperation eID, count, op )sg@HFhY' If op.Type="ShiftZ" Then Qx,jUL#2 DeleteOperation eID,count Zr`pOUk!4 count=count-1 {L 7O{:J End If :BFecS&i5 count=count+1 lc%2fVG-e Wend i^LLKx7M& 0_7A
< 'Set new z-shift }r`m(z$z op.Type = "ShiftZ" (9bFIvMc op.val1 = tlens 5[\mwUA op.parent = parID rap`[O|l= AddOperation eID, op zX+NhTTB Print "Set lens thickness = " & tlens ~5e)h_y mouLjT&p '************************************************************************* OmO/x 'Lens index of refraction *^]Hqf(` '************************************************************************* bnS"@^M eID = FindMaterial( "Lens" ) E;7vGGf] GetModelMaterial eID, mat D;%(Z! at_~b Ox6X mat.Nd = nlens XI#1) SetModelMaterial eID, mat O=c^Ak Print "Set lens index of refraction = " & nlens 7;H!F!K] Nrp0z: '************************************************************************* RtZK2 'Pupil diameter ~4HS
2\ '************************************************************************* u;$g13 eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) WVPnyVDc CT1)tRN 'Adjust pupil diameter (trimming volume inner hole) L[4Su;D 8sm8L\- SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" ZuV/!9qU 1+\ZLy!5: ' Adjust pupil location to just in front of the lens 5.st!Lp1 parID = FindFullName( "Geometry.Arizona Eye" ) i@7b eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) rSGp]W| count = 0 o /uA_19 While GetOperationCount(eID)>count <[9{Lg*D GetOperation eID, count, op \-A=??@H If op.Type="ShiftZ" Then k)+2+hX&> DeleteOperation eID,count ZMs$C3 count=count-1 ,dhSc<:LT End If R7xKVS_MP count=count+1 iC]=S} Wend {<f_,Nlc op.Type = "ShiftZ" e))fbv&V op.val1 = taq-0.01 Qs24b
op.parent = parID Q2wEt
>0a AddOperation eID, op DQ'yFPE .QRa{l_) Print "Set pupil diameter = " & pupilDiam cB~D3a0Th [~cb&6|M 'Update AZ Eye subassembly Description ;9w:%c1 eID = FindFullName( "Geometry.Arizona Eye" ) ".Lwq_ GetEntity eID, entity ~&bn}
M>W entity.Description = "Accommodation = " & A & "D" ` drds SetEntity eID, entity eJWcrVpn 5#Z> }@/ Update fJ
\bm Print "DONE!" +:@lde]/p obYXDj2 End Sub =7&2-'(@ Hggp*(AQK 如果屈光度是4,光瞳直径是4,则会输出如下数据: fB~BVYi {.vU; Accommodation = 4 Diopters r`? bYoz Pupil Diameter = 4 mm ^Fmp"[q Set aqueous humor thickness = 2.81 d@o1<Q Set anterior lens radius = 10.4 and conic constant = -2.375869 v;=F$3 Set posterior lens radius = -4.424557 and conic constant = -3.081019 zoFCHsr Set lens thickness = 3.927 E1p?v! Set lens index of refraction = 1.42672 +&t`"lRl& Set pupil diameter = 4 UPs7{We W DONE! U-uBz4Gha
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