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简介 egG<"e*W}N V+lF|CZb5 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。 ML\>TDt Rb0I7~Z%'d 模型 lcm[l `wt so 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。 1]~w?)..' A|+QUPD Table 1. AZ眼睛模型的定义 L0!CHP/nRS 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. RhHm[aN =8?Kn@nMN 光源 lh"*$.j- \_8wU'7 多个光源定义来分析该模型的不同特性。图1显示了所以的光源和提示信息告诉您他们可以用来做什么。 w90YlWS# b),fz v}Ju2 }IK 图1. 光源和提示信息使用 z.SC^/\o| 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 PZusYeV8b _#:/ ~Jp 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 l^Rb%?4Z y')OmR2h 图2. 字母F光源的设定方法光 E(PBV 87 s *lS 图3. 字母F在视网膜上位置点列图 PT6]qS'1 视网膜的散射 <R /\nY Xz b[<RcM{r} 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。
jhm??Af !&rd#ZBn l,4O 图4. 视网膜朗伯散射设定 -U=Ci 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 yk`qF'4] ]oB~8d )?$[iu7 s 图5. 视网膜重点采样规格设定 r!2U#rz 脚本 z~ C8JY: \c:$eF 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: 9aJIq{ `E E7MSoBX9M 图6. 用户对话框的创建与编辑 cQK-Euum 图7. 用户对话框编辑器 W}CM;~*L 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 ;2<5^hgk 余下的脚本计算与屈光度有关的所有参数。 IA@>'O tR|dnC4U 分析 Ku75YFO,5 /D&&7;jJ 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 H&)}Z6C" Db,"Gl 图7. 字母F在视网膜上颜色分析 ?q:|vt 脚本代码 IW0S*mO$ yWi-ic
[n Option Explicit 'Remove this to enable non-dimensioned variables to be used. 4#B'pJMw9 S<"Fp1#"l Dim entity As T_ENTITY q<dG}aj Dim op As T_OPERATION OM*c7& Dim mat As T_MODELMATERIAL B{nwQC b Dim A As Double KC6Cg?y^ Dim pupilDiam As Double gc.Lh~ Dim eID As Long r=H?fTY<3E Dim parID As Long K oJ=0jM# Dim count As Integer @AEH?gOX Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double aOwjYl[?p Dim tlens As Double, nlens As Double vk92j? Dim curv As Double, conic As Double Ek_5% n Dim ok As Long l-+=Yk!X h1w({<q*ov Sub Main {o}U"b<+Ra $4nAb^/ '用户输入对话框 @8|*Ndx2 Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 bv[#|^/ TextBox 220,21,40,21,.TextBox1 'default: 0 AE0uBv Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ]vvYPRV76 OKButton 40,91,90,21 }/cReX,so CancelButton 190,91,90,21 =-h^j Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 [.gk{> # TextBox 220,49,40,21,.TextBox2 'default: 4 7IX8ck[D End Dialog D=0YLQ*rP Dim dlg As UserDialog srGOIK. ?=? _32O ok = Dialog (dlg) `q?3ux XX8HSw!w If ok=0 Then 'cancel button was pressed xZ'fer`& Print "Execution cancelled." TN(Vzs% End iW5cEI%tb End If \}Jznzx; EeW
,-I 'Assign accommodation and pupil diameter & use defaults if field left empty X1Yw=t~a If dlg.TextBox1 = "" Then DrK]U}3fh" A = 0 'Default accommodation Z0,jg)sA4 Else x-BU$bx5 A = CDbl(dlg.TextBox1) o(*\MTt? End If 2S?7j[@%i` vO}r(kNJ If dlg.TextBox2 = "" Then %{u@{uG0'3 pupilDiam = 4 'Default pupil diameter F9fLJol Else $.PRav pupilDiam = CDbl(dlg.TextBox2) e\%,\uV} End If K:,V>DL (` *BZ_ Print " " \|HEe{nA Print "Accommodation = " & A & " Diopters" #Rw!a#CX. Print "Pupil Diameter = " & pupilDiam & " mm" wQhNQ(H~\ AV5={KK ' Calculate new parameters with accommodation p='j/= taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness \ruQx)5M Xw?DN*`L Rant = 12.0 - 0.4*A 'Radius of anterior lens ]o6ZZK CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens g)Lf^ mY"7/dw<v Rpost = -5.224557 + 0.2*A 'Radius of posterior lens EXDDUqZ5\ CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens ;wn9
21r %'Cj~An tlens = 3.767 + 0.04*A 'Lens thickness /2tA
n #])"1fk nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction }]x \ `}o HpnF,4A> 'Adjust parameters to account for accommodation j4~(6Imm L'+bVP{L '************************************************************************* n7[nl43 'Aqueous thickness (Position of Lens) `"5Ub,~ '************************************************************************* gRLt0&Q~ eID = FindFullName( "Geometry.Arizona Eye.Lens" ) tFmB`*!% GetCustomElement eID, entity N!+=5! uNyU]@R<W parID = FindFullName( "Geometry.Arizona Eye" ) w1/QnV \<7Bx[/D4 ' Delete any shift(s) in z -S sgW count = 0 Lq(=0U\"P While GetOperationCount(eID)>count ?P
kJG,~ GetOperation eID, count, op f:>y'#P If op.Type="ShiftZ" Then >h7(kj: DeleteOperation eID,count AyE*1 FD count=count-1 C QkY6 End If Q]WBH_j count=count+1 ynIe4b Wend <ToS& qc8Ge\3s 'Set new shift in jSI1tW8 op.Type = "ShiftZ" (?z?/4>7< op.val1 = taq `B%%2p& op.parent = parID Mu3G/|t( AddOperation eID, op 4.O) /0sU Print "Set aqueous humor thickness = " & taq-0.55 )N.3Q1g- s)-An(Uw '************************************************************************* )D8op;Fn 'Radius and conic constant of anterior lens 1Lb)S@Q`*R '************************************************************************* g}_2T\$k eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) q5f QTV GetConic eID, entity, curv, conic j7}mh ;4 ;gaf SetConic eID, entity, 1/Rant, CCant *AH`ob} Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ?C|'GkT '2^}de!E '************************************************************************* lNX*s
E
. 'Radius and conic constant of posterior lens #}7T$Va '************************************************************************* $kUB%\` eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) q{w|`vIb GetConic eID, entity, curv, conic !tq]kKJ3: <B6md
i'R SetConic eID, entity, 1/Rpost, CCpost ;[y( 14g Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost rJiF2 W PQaTS*0SXJ '************************************************************************* 7y
Cf3 'Lens thickness (Position of posterior lens surface) SeHrj&5U '************************************************************************* L^qCE-[ 13?:a[~=Y parID = FindFullName( "Geometry.Arizona Eye.Lens" ) Xu-~j! byM%D$R ' Delete any z-shift(s) /stvNIEa count = 0 ]]|#+$ ~ While GetOperationCount(eID)>count d+DO}=] GetOperation eID, count, op gC$_yd6m
L If op.Type="ShiftZ" Then ]L3U2H`7 DeleteOperation eID,count "Q@m7j)( count=count-1 .gO|=E" End If @Ou
H=<YN count=count+1 =z. hJu Wend _hY6NMw -6)n QNj| 'Set new z-shift %bw+>:Tr op.Type = "ShiftZ" uH\EV`@' op.val1 = tlens #$UwJ B]_D op.parent = parID )>~jjR AddOperation eID, op ;1&"]N% Print "Set lens thickness = " & tlens V Rv4p5 4U dk# '************************************************************************* !Q\*a-C 'Lens index of refraction L}
R"1O '************************************************************************* 4b<|jVl\ eID = FindMaterial( "Lens" ) M6wH$!zRa GetModelMaterial eID, mat Q0xGd(\ `)cI^! mat.Nd = nlens +2MF#{ tS SetModelMaterial eID, mat X3sAy(q Print "Set lens index of refraction = " & nlens j \rGU){
nc1~5eo '************************************************************************* k[ *9b:~ 'Pupil diameter dOv\] '************************************************************************* zU1D@ eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 7 7bwYKIn (?Ko:0+* 'Adjust pupil diameter (trimming volume inner hole) g=mKTk /)[-5n{ SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" i6yA>#^ < }K9 50 ' Adjust pupil location to just in front of the lens bIm4s parID = FindFullName( "Geometry.Arizona Eye" ) T;DKDga eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) eFsl count = 0 h GA2.{ While GetOperationCount(eID)>count 'jO2pH/% GetOperation eID, count, op 0j8fU7~6S If op.Type="ShiftZ" Then EY]H*WJJ DeleteOperation eID,count <Y6Vfee,& count=count-1
kb 74: End If d>u^7: count=count+1 y)K Iz Wend o|>=<l op.Type = "ShiftZ" 0WzoI2Q op.val1 = taq-0.01 f\5w@nX op.parent = parID Mq~E'g4# AddOperation eID, op MR|A_e^x i'<hT
q4 Print "Set pupil diameter = " & pupilDiam }t#|+T2f Pfs_tu 'Update AZ Eye subassembly Description 2XL^A[? eID = FindFullName( "Geometry.Arizona Eye" ) &'`C#-e@ GetEntity eID, entity Sm[#L`eqW entity.Description = "Accommodation = " & A & "D" {
1~]}K2 SetEntity eID, entity [? "hmSJ }c||$ Update 3B;Gm<fJ9N Print "DONE!" Yt*NIwWr MMk9rBf End Sub V=fu[#<@Ig 1<~n2} 如果屈光度是4,光瞳直径是4,则会输出如下数据: ^XeJZkLEB {8mJ<b>VA Accommodation = 4 Diopters ()j)}F#Z` Pupil Diameter = 4 mm ts&\JbL Set aqueous humor thickness = 2.81 &LI q? Set anterior lens radius = 10.4 and conic constant = -2.375869 47Vt8oyh% Set posterior lens radius = -4.424557 and conic constant = -3.081019 (]sm9PO Set lens thickness = 3.927 <zY#qFQ2 Set lens index of refraction = 1.42672 (XR}U6^v] Set pupil diameter = 4 /V0Put DONE! =mQY%l y}FG5'5$13 $'}| /D QQ:2987619807 GR(m+%Vw!
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