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简介 7WV"Wrl] D$hK 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。 M7DoAS{6e b#(QZ 模型 2Z(?pJyDM )x5w`N]lm 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。 V(G{_>> *{fZA;<R Table 1. AZ眼睛模型的定义 Ornm3%p+e 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. p,4S?cr>a gd)VL}k 光源 d.sn D)X N,)rrBD 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。 y_IF{%i &WbHM)_n 2 $Z4 >! 图1. 光源和提示信息使用 ,|O|gh$s 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。 m7,"M~\pX ?AQR\) P 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。 Y
Odwd}M neWx-O 图2. 字母F光源的设定方法光 .v) A|{:2 e~G IUwJ 图3. 字母F在视网膜上位置点列图 f+Bv8 g 视网膜的散射 r^d:Po ~\R+p~> 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。 (.M &nN'Ce bmC{d pr"q-S>E 图4. 视网膜朗伯散射设定 cTJG1'm 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。 ;>p{|^X0D H|N,nkhH} n\scOM)3 图5. 视网膜重点采样规格设定 6r5<uZ9w_X 脚本 0Q/BTT%X p6{8t} 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: 7baQ4QY?n i;<H^\% 图6. 用户对话框的创建与编辑 x8rp Z 图7. 用户对话框编辑器 k8sjW!2 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。 NSh~O!pX 余下的脚本计算与屈光度有关的所有参数。 "qY_O/Eg]] 5
.bU2C 分析 Gy[m4n~Z5 w#$Q?u ,G 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 [M.!7+$o "Kn%|\YL@4 图7. 字母F在视网膜上颜色分析 #c1c%27cmm 脚本代码 _E[)_yH'- OEgp!J Option Explicit 'Remove this to enable non-dimensioned variables to be used. I_h&35^t :'gX//b): Dim entity As T_ENTITY ~LN
{5zg Dim op As T_OPERATION uHO>FM, Dim mat As T_MODELMATERIAL 8DJoQl9 Dim A As Double |NWo.j>4- Dim pupilDiam As Double jUX0sRDk Dim eID As Long 7pz #%Hf Dim parID As Long }Ias7d?re Dim count As Integer r`CsR0[ Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double
lxD~[e Dim tlens As Double, nlens As Double k|
,F/: Dim curv As Double, conic As Double g~$cnU Dim ok As Long h>'Mh;+ L Z#SX5N Sub Main ],ISWb nx'D&,VX '用户输入对话框 .q(1 Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 v|u[BmA)*k TextBox 220,21,40,21,.TextBox1 'default: 0 CrI:TB>/" Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 n[`FoY OKButton 40,91,90,21 9TbRrS09 CancelButton 190,91,90,21 .~dNzonq Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 c'~6 1HA< TextBox 220,49,40,21,.TextBox2 'default: 4 uz;z+Bd^ End Dialog =?gB@vS Dim dlg As UserDialog 0T7""^'& 7gcJ.,Z. ok = Dialog (dlg) S+&Bf ~~D `Kq4z62V If ok=0 Then 'cancel button was pressed IX)\z Print "Execution cancelled." P+nd?:cz End uMe]].04 End If aaM76; o79EDPX 'Assign accommodation and pupil diameter & use defaults if field left empty ?#P@N4Uw}y If dlg.TextBox1 = "" Then JQ)w/@Vu= A = 0 'Default accommodation S
7 *LV; Else m_g2Cep A = CDbl(dlg.TextBox1) tjTnFP/= End If (7_}UT@w- &`IC3O5 If dlg.TextBox2 = "" Then }grel5lq pupilDiam = 4 'Default pupil diameter 0B?t:XU , Else P4S]bPIp pupilDiam = CDbl(dlg.TextBox2) G :JQ_w End If $,9A?' ^J-\s_)" Print " " iy\ 6e k1 Print "Accommodation = " & A & " Diopters" K/Qo~
Print "Pupil Diameter = " & pupilDiam & " mm" n6]8W^g (Ld,<!eN0 ' Calculate new parameters with accommodation #.^A5`k taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness soXIPf VuWBWb?0Q Rant = 12.0 - 0.4*A 'Radius of anterior lens <@z!kl CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens ^>ICycJ B
LI
9(@ Rpost = -5.224557 + 0.2*A 'Radius of posterior lens qlgo#[i CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens Yy3g7!K5E Ri mz~}+ tlens = 3.767 + 0.04*A 'Lens thickness dF<GuS;l5 jZ\a:K? nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction \hr2#! E+!A0!1 'Adjust parameters to account for accommodation 70BLd(? n3Q Rn^ '************************************************************************* nA?Ks!9T 'Aqueous thickness (Position of Lens) nWz7$O '************************************************************************* $]t3pAI[H0 eID = FindFullName( "Geometry.Arizona Eye.Lens" ) -L&%,% GetCustomElement eID, entity s7>a A5[iFT> parID = FindFullName( "Geometry.Arizona Eye" ) MGU%"7i'} 'V#$PZx ' Delete any shift(s) in z F2:nL`]b[ count = 0 'NYW`, While GetOperationCount(eID)>count $4ZjN N@ GetOperation eID, count, op *H({q`j33k If op.Type="ShiftZ" Then O-jpS?@ DeleteOperation eID,count l1I\khS count=count-1 [;RO= End If O=E?m=FR" count=count+1 Hru~Y}V Wend 0Mu6R=s h1AZ+9 'Set new shift in ly~tB LH} op.Type = "ShiftZ" Xdtyer% op.val1 = taq b[s=FH]#N op.parent = parID f~?4 AddOperation eID, op f5o##ia7: Print "Set aqueous humor thickness = " & taq-0.55 cy
@",z J[ 7Sf^r '************************************************************************* ,?/AIL]_ 'Radius and conic constant of anterior lens .TpM3b#r '************************************************************************* o<8SiVC2 eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) eRm 9LOp GetConic eID, entity, curv, conic yYN _]&ag &\>. j| SetConic eID, entity, 1/Rant, CCant Pof]9qE-y Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant *1c1XN<7 3K{G =WE$ '************************************************************************* G A+#'R
'Radius and conic constant of posterior lens Yx"un4 '************************************************************************* h=
Mmd eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 9L7jYy=A# GetConic eID, entity, curv, conic %s*F~E (F=q/lK$ SetConic eID, entity, 1/Rpost, CCpost "l[ c/q[ Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost -ztgirU XkRPD '*************************************************************************
YG K7b6
'Lens thickness (Position of posterior lens surface) h"ZR`?h '************************************************************************* bBg=X}9 B6J< parID = FindFullName( "Geometry.Arizona Eye.Lens" ) Ce`#J6lT @aY>pr5! ' Delete any z-shift(s) *wp>a?sG\ count = 0 VbfTdRD- While GetOperationCount(eID)>count 7;r Jr&.) GetOperation eID, count, op h;DLD8L If op.Type="ShiftZ" Then ,0\Pr DeleteOperation eID,count V_"UiN"o count=count-1
+
C'<* End If *Eg[@5;QA count=count+1 Q|7l!YTzVu Wend B
x-"<^< Zg=jDPt} 'Set new z-shift 6BH
P#B2j op.Type = "ShiftZ" oxZXY]$y op.val1 = tlens HA`qU
op.parent = parID JDP /vNq AddOperation eID, op B0$ge"FK9 Print "Set lens thickness = " & tlens 0'zX6% ;GV~MH-F '************************************************************************* Mem1X rBH 'Lens index of refraction Ju"K" '************************************************************************* ,%d?gi"& eID = FindMaterial( "Lens" ) [DD#YL\P GetModelMaterial eID, mat vR*p1Kq: .!Q*VTW mat.Nd = nlens (8Q*NZ SetModelMaterial eID, mat ;/ASl<t, Print "Set lens index of refraction = " & nlens [
~:wS@% L['g')g. '************************************************************************* 'bn$"A"{o 'Pupil diameter ~%?LFR' '************************************************************************* bwyj[:6l eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) BFvRU5&Sz vocWV/ 'Adjust pupil diameter (trimming volume inner hole) HyC826~-rI 'mYUAVmSC# SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" #u/5
nm FwwOp"[~t ' Adjust pupil location to just in front of the lens g]Z@_ parID = FindFullName( "Geometry.Arizona Eye" ) H6Q!~o\"H eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) ;5&=I|xqe count = 0 "@(Sw>*o While GetOperationCount(eID)>count +j(7.6ia GetOperation eID, count, op i%n9RuULh If op.Type="ShiftZ" Then xz3|m
_) DeleteOperation eID,count bx:j`5Uj` count=count-1 ,w%hD* End If su0q 2. count=count+1 QC<O=<$Q[ Wend q!y!=hI op.Type = "ShiftZ" X?++I4\ op.val1 = taq-0.01 L "5;< op.parent = parID tJII-\3" AddOperation eID, op =4#p|OZP (d*~Qpi{7 Print "Set pupil diameter = " & pupilDiam 7bY N O&evv8 6L 'Update AZ Eye subassembly Description vVf%wei^# eID = FindFullName( "Geometry.Arizona Eye" )
;(
[^+_/ GetEntity eID, entity cCv@fks entity.Description = "Accommodation = " & A & "D" e/R$Sfj] SetEntity eID, entity /3j3'~0 )-^[;:B\k" Update z8<" Print "DONE!" \pVNJy$`< Dd'J"|jF38 End Sub En{<
OMg KJi8LM 如果屈光度是4,光瞳直径是4,则会输出如下数据: }ws(:I^ -\~HAnh Accommodation = 4 Diopters ,qwVDYJ Pupil Diameter = 4 mm K$c?:?wmo Set aqueous humor thickness = 2.81 :aR_f`KMm Set anterior lens radius = 10.4 and conic constant = -2.375869 "Bl6)qw Set posterior lens radius = -4.424557 and conic constant = -3.081019 '}9 %12\^h Set lens thickness = 3.927 h3j`X' Set lens index of refraction = 1.42672 nG~^-c+ Set pupil diameter = 4 t/J|<Ooj? DONE! C&f{LpB` K>_~|ZN1C8 |Ge!;v QQ:2987619807 ?0?+~0sI
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