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简介 ]\5@N7h _'<V<OjVM! 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。 =2uE\6Fl, !O
F#4N 模型 ?xh_qy; !t "uNlN 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。 -B:Z(]3#\ (1JZuR<?c Table 1. AZ眼睛模型的定义 j[NA3Vj1P 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. 2uFaAAT v'i"Q 光源 Hn)K;?H4 d,[.=Jqv[ 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。 X<@yt HBv ,Hh7'` nL!h hseH 图1. 光源和提示信息使用 S!.aBAW 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。 3S1V^C-eBx {:m5<6?x) 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。 0h!2--Aur h`+Gs{1qw 图2. 字母F光源的设定方法光 HRIf)n&~f MK9?81xd 图3. 字母F在视网膜上位置点列图 yq+<pfaqvK 视网膜的散射 ^(m`5]qr7J )?~3fb6^ 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。 #b\&Md|; ;y<)RM Hb'fEo r 图4. 视网膜朗伯散射设定 )|,-l^lC 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。 Ht?
u{\p@ +4\JY"oi ,e+.Q#r*Y 图5. 视网膜重点采样规格设定 b0X*+q 脚本 :Q2\3 Z)'jn8?P 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: _Ptf^+ +JZ<9,4 图6. 用户对话框的创建与编辑 ]_I<-}?; 图7. 用户对话框编辑器 V\ch0i
1 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。 q_>DX,A 余下的脚本计算与屈光度有关的所有参数。 \<|a>{`7]i AKx\U?ei7 分析 }D
dg ;hF >iw 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 s=#IoNh @dX0gHU[c 图7. 字母F在视网膜上颜色分析 asP>(Li 脚本代码 a8M.EFa: *{W5QEa Option Explicit 'Remove this to enable non-dimensioned variables to be used. S$W
*i@x? 7}Z.g9< Dim entity As T_ENTITY LW_Y Dim op As T_OPERATION ( f8g}2 Dim mat As T_MODELMATERIAL .Y'kDuUu Dim A As Double ;nLQ?eS\ Dim pupilDiam As Double o;FjpZ Dim eID As Long #[sC H Dim parID As Long V'c9DoSRI\ Dim count As Integer ;1S{xd*^N Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double <9-tA\`8N Dim tlens As Double, nlens As Double iJ42` 51 Dim curv As Double, conic As Double N\H{p%8 Dim ok As Long U"-mLv"| y[qW> Sub Main meR%);\ GEA@AD=^f '用户输入对话框 }llzO Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 l*_b)&CH TextBox 220,21,40,21,.TextBox1 'default: 0 )ty
*_@N0 Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ;Iw'TF OKButton 40,91,90,21 *[
Wh9 ,H CancelButton 190,91,90,21 ~J)4 (411 Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 )_+" TextBox 220,49,40,21,.TextBox2 'default: 4 v7O{8K+ End Dialog [KWF7GQi Dim dlg As UserDialog fouy?? S7aS Ut! ok = Dialog (dlg) wX#\\Jgi dcU|y%k% If ok=0 Then 'cancel button was pressed WSDNTfpI Print "Execution cancelled." f:7Y End F
xFK End If ~SM2W% (4ow0}1 'Assign accommodation and pupil diameter & use defaults if field left empty a9QaF s" If dlg.TextBox1 = "" Then PG<N\ A = 0 'Default accommodation :KX/` Else 1Od:I}@ A = CDbl(dlg.TextBox1) _?kf9 . End If q,u>`]} -rH4/Iby If dlg.TextBox2 = "" Then fhH* R*4 pupilDiam = 4 'Default pupil diameter 2:p2u1Q
O Else b${Kj3( pupilDiam = CDbl(dlg.TextBox2) pe,c End If DX$`\PA I_pA)P*Q(6 Print " " 42z9N\ f Print "Accommodation = " & A & " Diopters" k%In
Print "Pupil Diameter = " & pupilDiam & " mm" M*c\=( bs+KcY:N] ' Calculate new parameters with accommodation 7Fy^K;V" taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness Tj:+:B(HB J\;~(:
~ Rant = 12.0 - 0.4*A 'Radius of anterior lens v{% /aw CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens "a,Tc2xk 2vWkAC; Rpost = -5.224557 + 0.2*A 'Radius of posterior lens uT-WQ/id CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens MIR17%G }ZYK3F tlens = 3.767 + 0.04*A 'Lens thickness E\V>3rse ew`R=<mZ,7 nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction @~63%6r#4M 1>1|>% 'Adjust parameters to account for accommodation Ccc6 ko_ N_gjOE`x5 '************************************************************************* ~MhPzu&B 'Aqueous thickness (Position of Lens) m};_\Db` '************************************************************************* 3\(s=-vh eID = FindFullName( "Geometry.Arizona Eye.Lens" ) [MiD%FfcNH GetCustomElement eID, entity TfZO0GL$ B=Zo0p^ parID = FindFullName( "Geometry.Arizona Eye" ) !)\`U/.W
>_F&oA# ' Delete any shift(s) in z |23 }~c, count = 0 (nE$};c<b2 While GetOperationCount(eID)>count ZVGw@3 GetOperation eID, count, op H/, tE0ZV If op.Type="ShiftZ" Then fmSw%r|pT DeleteOperation eID,count /(}V!0\? count=count-1 TTOd0a End If U|
N`X54 count=count+1 6=')*_~/ Wend (g4g-"rc pt0H*quwI 'Set new shift in ;3?M?E/$s op.Type = "ShiftZ" d>AVUf<o~ op.val1 = taq vuAAaKz op.parent = parID 17
j7j@s) AddOperation eID, op F~DG:x~ Print "Set aqueous humor thickness = " & taq-0.55
JI*ikco- S`6'~g '************************************************************************* "QlCcH`g 'Radius and conic constant of anterior lens /kJ*WA?J '************************************************************************* \`XJz{Lm] eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) /60[T@Mz GetConic eID, entity, curv, conic =x^I 5Pn !t_,x= SetConic eID, entity, 1/Rant, CCant O]PfQ Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant n!N;WL3k UfkRY<H '************************************************************************* 9m'[52{o 'Radius and conic constant of posterior lens ivagS\Q '************************************************************************* @O3w4Zs eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) pDKJLa GetConic eID, entity, curv, conic E""/dC:B #mM&CscE SetConic eID, entity, 1/Rpost, CCpost _*;cwMne- Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost We4 FR4` q%y_<Fw#E '************************************************************************* Ke/P[fo 'Lens thickness (Position of posterior lens surface) rxz3Mqg '************************************************************************* +<q^[<pS )RkU='lB " parID = FindFullName( "Geometry.Arizona Eye.Lens" ) C )I"yeS. JDhA{VN6 ' Delete any z-shift(s) ^Qr
P.l#pZ count = 0 c]"B)I1L While GetOperationCount(eID)>count lLJb3[
e. GetOperation eID, count, op ,Utw!] If op.Type="ShiftZ" Then G|MDo|q] DeleteOperation eID,count 54;iLL count=count-1 bFVdv&
End If Mb9q<4 count=count+1 Z8 # I Wend $x)'_o}e m3XH3FgKz 'Set new z-shift )N6R# op.Type = "ShiftZ" mvL'l) op.val1 = tlens g SwG=e\ op.parent = parID w|Mj8Lc+ AddOperation eID, op (o:CxhV Print "Set lens thickness = " & tlens ?I0 i%nH !'gz&3B~h '************************************************************************* Nb8<8O
^ 'Lens index of refraction (gf\VYM-7 '************************************************************************* sogbD9Jc eID = FindMaterial( "Lens" ) #wd \& GetModelMaterial eID, mat B~aOs>1
S] x2B"%3th0 mat.Nd = nlens ]q3Kd{B SetModelMaterial eID, mat ?rOb?cu- Print "Set lens index of refraction = " & nlens 6P~"7k [!q&r(-K '************************************************************************* qB39\j 'Pupil diameter b
mm@oi '************************************************************************* $`Xx5Ts7 eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) VoyH: Y1'.m5E 'Adjust pupil diameter (trimming volume inner hole) StDmJ] 2%qn!+. SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" 'f}S,i +q d-<y'GYw
' Adjust pupil location to just in front of the lens )f!dG(\ parID = FindFullName( "Geometry.Arizona Eye" ) _%2Umy| eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) pjCWg4ya count = 0 )eFFtnu5 While GetOperationCount(eID)>count )[)]@e GetOperation eID, count, op G}-.xj] If op.Type="ShiftZ" Then #rpqt{ml DeleteOperation eID,count 9v
F2aLPk count=count-1 Ntnmd End If u/[]g+ count=count+1 GA_`C"mx Wend N.G*ii\ op.Type = "ShiftZ" SN{*:\>, op.val1 = taq-0.01 7
h1"8#X op.parent = parID s4gNS
eA AddOperation eID, op xs I/DW 9$,gTU_a Print "Set pupil diameter = " & pupilDiam /8MQqZ C Qkib;\2 'Update AZ Eye subassembly Description _o?(t\B9{ eID = FindFullName( "Geometry.Arizona Eye" ) ]Z-oUO
Z<k GetEntity eID, entity G; [AQ:Iy entity.Description = "Accommodation = " & A & "D" .lBY"W&{ SetEntity eID, entity M',D bQy%$7UmX, Update J=X%
xb Print "DONE!" =[K)<5,@ hu|hOr8 End Sub ]X~g@O{>_ .G_3blE; 如果屈光度是4,光瞳直径是4,则会输出如下数据: o w_y p}A4K#G Accommodation = 4 Diopters M91lV(Z Pupil Diameter = 4 mm unnx#e] Set aqueous humor thickness = 2.81 !NYM(6!( Set anterior lens radius = 10.4 and conic constant = -2.375869 iL_F*iK5 Set posterior lens radius = -4.424557 and conic constant = -3.081019 2]3HX3 Set lens thickness = 3.927 :dguQ|e Set lens index of refraction = 1.42672 E)O|16f|> Set pupil diameter = 4 9I\3T6&tr DONE! ZGpTw[5ql
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