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简介 )!=X?fz,O )H*BTfmt 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。 kSjvY&n% ]l=iKl 模型 4{ED~w|
4{D^ 4G 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。 W!b'nRkq tAS[T9B Table 1. AZ眼睛模型的定义 rCdTn+O2 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. \|R\pS}4 _j\8u`^n 光源 7k#0EhN 1> 6oq/\D$6~ 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。 s[u*~A nm@.]
"/ -dH]_ 图1. 光源和提示信息使用 Ak@y"!wnM 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。 BBRZlx F Xp_`9.zH 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。 ^J&}C $8NM[R.8^4 图2. 字母F光源的设定方法光 O?qM=W OC Wyp 图3. 字母F在视网膜上位置点列图 |DXi~ 视网膜的散射 tx}=c5 ~4`3p=$ 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。 *XluVochrb 7m;<b$ NrfAr}v'E 图4. 视网膜朗伯散射设定 8:"s3xaO3 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。 c#8@>; I\$?'q> 'F Cmbry 图5. 视网膜重点采样规格设定 x8RiYi+ 脚本 /*m6-DC ST[E$XL6 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: 2%~+c|TH.) pw=o}-P{ 图6. 用户对话框的创建与编辑 .-.b:gdO( 图7. 用户对话框编辑器 /3qKsv# 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。 XOPiwrg%p 余下的脚本计算与屈光度有关的所有参数。 kFQx7m 7G
3e 分析 QT[4\) wo\O0?d3{ 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 \kC'y9k lLNI5C 图7. 字母F在视网膜上颜色分析 9mB] \{^ 脚本代码 He}"e&K v=x)]<E"_ Option Explicit 'Remove this to enable non-dimensioned variables to be used. F&D,y-CQ LCok4N$o Dim entity As T_ENTITY :Oi}X7\ Dim op As T_OPERATION B1z7r0Rm, Dim mat As T_MODELMATERIAL eY3<LVAX Dim A As Double 4+F@BxpB Dim pupilDiam As Double C@9K`N[* Dim eID As Long !>6`+$=U Dim parID As Long !s[gv1 Dim count As Integer km6O3>p5r Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double qDjH^f Dim tlens As Double, nlens As Double G(#EW+ Dim curv As Double, conic As Double sxPvi0> Dim ok As Long
`6pz9j] @4P_Yfn Sub Main a#+;BH1 .8]=yPm '用户输入对话框 e
J:#vX86 Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 DN|+d{^lN TextBox 220,21,40,21,.TextBox1 'default: 0 Nd**":i$ Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 c"NGE OKButton 40,91,90,21 @Qd5a(5W M CancelButton 190,91,90,21 -z>m]YDH Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 cp4~`X TextBox 220,49,40,21,.TextBox2 'default: 4 ,-1d2y End Dialog ^[1Xl7)` Dim dlg As UserDialog MG3xX;
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vW{1 ok = Dialog (dlg) "tmr
s_~ pm:#@sl If ok=0 Then 'cancel button was pressed L^L.;1 Print "Execution cancelled." j/hm)*\io End K9S(Xip End If JUTlJyx8 ^*WO*f>y 'Assign accommodation and pupil diameter & use defaults if field left empty gX/? If dlg.TextBox1 = "" Then 0t)5K O A = 0 'Default accommodation j]6YLM@5$ Else z<8WN[fB A = CDbl(dlg.TextBox1) 10m`LG End If CjLiLB
W(PNw2 If dlg.TextBox2 = "" Then [V41 Gk pupilDiam = 4 'Default pupil diameter ~oeX0l>F Else c1g'l.XL
3 pupilDiam = CDbl(dlg.TextBox2) 2.&%mSN End If k<%y+v (o1o);AO Print " " Gvc/o$_ Print "Accommodation = " & A & " Diopters" `&SBp }W} Print "Pupil Diameter = " & pupilDiam & " mm" *%2,=
p VQn]"G(` ' Calculate new parameters with accommodation ,ydn]0SS taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness /^, /o ;i&t|5y~ Rant = 12.0 - 0.4*A 'Radius of anterior lens I6[=tB CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens *NQsD C.J^ =${ImMwj Rpost = -5.224557 + 0.2*A 'Radius of posterior lens Z xR CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens LO)p2[5#R .a}!!\@ tlens = 3.767 + 0.04*A 'Lens thickness (sEZNo5 n 5hp)Z7 nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction 10r9sR ~uEI}z 'Adjust parameters to account for accommodation +aRHMH r[AqA '************************************************************************* i{k v$ir! 'Aqueous thickness (Position of Lens) QE`u~ '************************************************************************* %?!TqJT?{ eID = FindFullName( "Geometry.Arizona Eye.Lens" ) l"9$lF} GetCustomElement eID, entity -FQS5Zb.! _&PF (/w parID = FindFullName( "Geometry.Arizona Eye" ) 5} 1qo7; tj[-|h ' Delete any shift(s) in z CMHg]la count = 0 0]l9x} While GetOperationCount(eID)>count t&rr;W] GetOperation eID, count, op h($Jo If op.Type="ShiftZ" Then #v:A-u DeleteOperation eID,count <}1GYeP count=count-1 l# |M.V6G End If | @p count=count+1 Px?0)^"2 Wend 2G}@s.iE .
"`f~s\G 'Set new shift in G3de<?K.[V op.Type = "ShiftZ" AI3\eH+ op.val1 = taq c.h_&~0qf op.parent = parID $TavvO%# AddOperation eID, op pcPRkYT[M Print "Set aqueous humor thickness = " & taq-0.55 $>=w<=r|;
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'************************************************************************* Y,d|b V*FH 'Radius and conic constant of anterior lens o.>Yj)U '************************************************************************* PsI{y&. eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) KZwzQ" Hl GetConic eID, entity, curv, conic ^tl&FWF @D@'S:3 SetConic eID, entity, 1/Rant, CCant &%@>S. Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant A9M/n^61 Kg#s<# h '************************************************************************* DWu~%U8 'Radius and conic constant of posterior lens q4ej7T8 '************************************************************************* qgsw8O& eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) s:Z1
ZAxv GetConic eID, entity, curv, conic u|\K kk r%^XOw<' SetConic eID, entity, 1/Rpost, CCpost No(S#,vJ; Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost mcSZ1d~,( hVu~[ 'Me '************************************************************************* ^j]"5@f 'Lens thickness (Position of posterior lens surface) =8x-+u5}rK '************************************************************************* ]8EkZC |sV@j_TX parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ((tWgSZ3 q@iZo,Yk ' Delete any z-shift(s) *uMtl' count = 0 lK #~lC While GetOperationCount(eID)>count 2T}FX4' GetOperation eID, count, op Z n]e2 If op.Type="ShiftZ" Then a|@1RH>7H DeleteOperation eID,count WvHy}1W count=count-1 <^B!.zQ End If JL&ni]m count=count+1 dF0:'y Wend jX
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iU~p 'Set new z-shift "aeKrMgc6V op.Type = "ShiftZ" ? p^ ':@= op.val1 = tlens &6@e9ff0 op.parent = parID }}~ t!/x AddOperation eID, op p|R]/C0f Print "Set lens thickness = " & tlens DqlspT {$^Lb4O[V '************************************************************************* wq`\p['Q, 'Lens index of refraction 'C\knQ '************************************************************************* bL18G(5 eID = FindMaterial( "Lens" ) D_Cd^;b GetModelMaterial eID, mat C$fQ[@ m4kUA"n5 mat.Nd = nlens 4p_@f^v~QH SetModelMaterial eID, mat [[d@P%X& Print "Set lens index of refraction = " & nlens E9n7P'8 &1,qC,:! '************************************************************************* 3W}xYYs]^ 'Pupil diameter Wy,Tf*[ '************************************************************************* vCtag]H2@ eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ShRkL< h5R5FzY0& 'Adjust pupil diameter (trimming volume inner hole) NuKx{y}P RBM4_L SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" OL)M`eVQ' b-,]21 ' Adjust pupil location to just in front of the lens h; sdm/ parID = FindFullName( "Geometry.Arizona Eye" ) B|n<{g[-cM eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 'Z(4Wuwb count = 0 9:jZ3U While GetOperationCount(eID)>count \m;"KyP+ GetOperation eID, count, op [!E~pW%|n If op.Type="ShiftZ" Then *FEY"W+bY DeleteOperation eID,count >VWH
bo count=count-1 haMt2S2_B: End If dLI`\e<r&[ count=count+1 _w>9Z>PR Wend J#'+&DH op.Type = "ShiftZ" Gr?[s'Ze op.val1 = taq-0.01 1ssEJ;#s op.parent = parID h*-j
AddOperation eID, op fr<, LC.
[{!5{k! Print "Set pupil diameter = " & pupilDiam A1,- qv1s m]NyEMYg 'Update AZ Eye subassembly Description b bO1`b- eID = FindFullName( "Geometry.Arizona Eye" ) B?tO&$s GetEntity eID, entity y-c2tF@'v entity.Description = "Accommodation = " & A & "D" 7T3ub3\ SetEntity eID, entity /^z5;aG *qm@;!C Update saaN$tU7 Print "DONE!" /N&)r wc <C9_5Ce~ End Sub Hc{0O7 )gR !G]Y 如果屈光度是4,光瞳直径是4,则会输出如下数据: ;eRYgC va/$dD9 Accommodation = 4 Diopters 7}<057Xn' Pupil Diameter = 4 mm 9}2E+ Set aqueous humor thickness = 2.81 *0`oFTJ Set anterior lens radius = 10.4 and conic constant = -2.375869 4W''j[Y/ Set posterior lens radius = -4.424557 and conic constant = -3.081019 Ih.6"ISK} Set lens thickness = 3.927 a jCx"J Set lens index of refraction = 1.42672 ;9hi2_luV Set pupil diameter = 4 C%csQ m DONE! DEw_dOJ(
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