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简介 y8|?J\eRy RJO40&Z<Z 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。 WZ]f \S 2!E@Gbhm5 模型 csNB
\ sfwlv^ 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] =q>p ^;=L|{Xl Table 1. AZ眼睛模型的定义 /swNhDQ"o 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. OPP^n-iPr 8,m3]Lg 光源 `R+I(Cb @.SuHd 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。 ]31UA>/TI _)6 N&u8 D<:J6W7] 图1. 光源和提示信息使用 `7mRUDz 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。 #FQkwX'g H 6~6hg 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。 n%Df6zQ<@s N+M^e`H 图2. 字母F光源的设定方法光 Obb"#W@3 y_e$W3bON, 图3. 字母F在视网膜上位置点列图 wSwDhOX= 视网膜的散射 xJSK" D8S3YdJ 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 XwNJHOaF KqNbIw*sR yl'@p5n 图4. 视网膜朗伯散射设定 &3t[p= 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 ,9@JBV%_ A;\1`_i0 dW`!/OaQD 图5. 视网膜重点采样规格设定 n^P~]1i 脚本 |1[3RnGS ]/klKqz 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: 4`M7
3k0 wTw)GV4 图6. 用户对话框的创建与编辑 *eLKD_D`!C 图7. 用户对话框编辑器 AZgeu$:7p< 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。 ccPTJ/%$ 余下的脚本计算与屈光度有关的所有参数。 jF r[T Zl4X,9Wt 分析 Or9"T ]z O7of9F~" 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 k(bDj[0q^ _hz}I>G@B 图7. 字母F在视网膜上颜色分析 Uzzt+Iwm 脚本代码 B2/d%B #FNSE*Y Option Explicit 'Remove this to enable non-dimensioned variables to be used. v%2 @M E@(nKe&6T_ Dim entity As T_ENTITY ?Xq"Q^o4#e Dim op As T_OPERATION xxS>O% Dim mat As T_MODELMATERIAL CNkI9>L=W` Dim A As Double Vhi4_~W3j] Dim pupilDiam As Double )A1u uW ( Dim eID As Long )4tOTi[ Dim parID As Long G3wkqd Dim count As Integer Nm.G,6<J Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double aF!Im} Dim tlens As Double, nlens As Double &Fg|52 Dim curv As Double, conic As Double wdo(K.m Dim ok As Long ZCC T hq|I%>y Sub Main {IgLH`@ |mp~d<& '用户输入对话框 [0M`uf/u Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 92 oUQ EK TextBox 220,21,40,21,.TextBox1 'default: 0 y`Nprwb Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 CAT{)*xc OKButton 40,91,90,21 JV`"kk/ CancelButton 190,91,90,21 FD[o94`% Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ,%X"Caz TextBox 220,49,40,21,.TextBox2 'default: 4 Zb4+zps^- End Dialog ]p-xds#d Dim dlg As UserDialog >.o<}!FW iz-B)^8. ok = Dialog (dlg) o^8Z cN> fG_<HJS(~ If ok=0 Then 'cancel button was pressed ^(+@uuBx Print "Execution cancelled." B{hV|2 End 3n3$? oV End If Z(Z$>P&4 9@^N*
E+ 'Assign accommodation and pupil diameter & use defaults if field left empty N#<X"&-_# If dlg.TextBox1 = "" Then F"| ; A = 0 'Default accommodation Qu_=K_W Else 0 H0U%x8 A = CDbl(dlg.TextBox1) 9cXL4 End If K0'= O w/,A@fLL If dlg.TextBox2 = "" Then *ORa@x pupilDiam = 4 'Default pupil diameter $g&_7SJ@ Else ZU68\cL pupilDiam = CDbl(dlg.TextBox2) <0btwsv} End If vtw97G k!0vpps Print " " @>q4hYF Print "Accommodation = " & A & " Diopters" .Mxt
F\ Print "Pupil Diameter = " & pupilDiam & " mm" 8'-E>+L ">v-CSHY ' Calculate new parameters with accommodation =:=s taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness :/\KVz'fw} gHox>r6.A Rant = 12.0 - 0.4*A 'Radius of anterior lens )u=46EU_ CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens '>:%n `1i\8s&O6@ Rpost = -5.224557 + 0.2*A 'Radius of posterior lens ;-quK%VO! CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens 4&<zkAMR lFV\Go tlens = 3.767 + 0.04*A 'Lens thickness $VJE&b X&gXhr#dL\ nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction p?'
F$Wz j)mi~i*U 'Adjust parameters to account for accommodation ZK`x(h{p) p?#xd!tc2N '************************************************************************* 1[]V @P^ 'Aqueous thickness (Position of Lens) Mi<}q@]e '************************************************************************* S #C;"se eID = FindFullName( "Geometry.Arizona Eye.Lens" ) ')Qb,#/,% GetCustomElement eID, entity 5|g#>sx>`q asJ t6C parID = FindFullName( "Geometry.Arizona Eye" ) GXwQ
)P5] tN_~zP ' Delete any shift(s) in z fiQ/ &]|5 count = 0 $%zM Z While GetOperationCount(eID)>count 2#Y5*r's\ GetOperation eID, count, op X<uH [ If op.Type="ShiftZ" Then uz@lz + DeleteOperation eID,count 7
aN}lQM count=count-1 bJB*w End If oRHWb_$" count=count+1 \ocC'FmE Wend S~\u]j^%y eo<=Q|nI& 'Set new shift in 7!q.MOYm op.Type = "ShiftZ" mU;\,96# op.val1 = taq `r+`vJ$ op.parent = parID e$4l[&kH_ AddOperation eID, op Z`yW2ON$' Print "Set aqueous humor thickness = " & taq-0.55 ;|.IUXEgcF @\Yu?_a '************************************************************************* [p96H)8YU 'Radius and conic constant of anterior lens =%0r_#F%= '************************************************************************* Ombvp; eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 2^fSC`! GetConic eID, entity, curv, conic ~c|{PZ9U D1~3 3; SetConic eID, entity, 1/Rant, CCant c59l/qoz Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant p}
i5z_tS !po29w:S '************************************************************************* )5l9!1j 'Radius and conic constant of posterior lens \"Aw
ATQ '************************************************************************* bEl)/z*gy/ eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) ?q hme GetConic eID, entity, curv, conic (\ Gs7 fMIKA72>{ SetConic eID, entity, 1/Rpost, CCpost Q);^gV Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 22"/|S Gu\lV c '************************************************************************* X-J<gI(Y 'Lens thickness (Position of posterior lens surface) QiQO>r '************************************************************************* Z{
b($po >@StKj parID = FindFullName( "Geometry.Arizona Eye.Lens" ) zP#%ya:I |d=MX>i|G ' Delete any z-shift(s) )Tj\ym-Vl count = 0 @(s"5i.`) While GetOperationCount(eID)>count ,XmyC7y< GetOperation eID, count, op a[Oi If op.Type="ShiftZ" Then H8?Kgaj~vf DeleteOperation eID,count :EZ"D#>y~ count=count-1 }|4dEao\ End If CDgu`jj%] count=count+1 Qh@A7N/L Wend J(%kcueb
%)G]rta# 'Set new z-shift \k)(:[^FY op.Type = "ShiftZ" XV*uu "F op.val1 = tlens b+ J) op.parent = parID mqb6 MnK - AddOperation eID, op V-%Am Print "Set lens thickness = " & tlens d`&F )gP0+W!u '************************************************************************* cQldBc 'Lens index of refraction i-_ * 5%A '************************************************************************* XhxCOpO eID = FindMaterial( "Lens" ) RE}$(T= GetModelMaterial eID, mat 'hl4cHk14 WZJ}HHePr mat.Nd = nlens 1b-_![&]1 SetModelMaterial eID, mat #jNN?,ZK Print "Set lens index of refraction = " & nlens `+O7IyTMA yZ]u{LJS '************************************************************************* o$-!E(p 'Pupil diameter L.) 0!1 '************************************************************************* ]:vo"{*C eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) ^z\*;
f \%+5p"Z< 'Adjust pupil diameter (trimming volume inner hole) p!xCNZ(m OFe?T\dQn SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" +>wBGVvS XUp'wP ' Adjust pupil location to just in front of the lens =vZF/r parID = FindFullName( "Geometry.Arizona Eye" ) ~i y]X:U eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) X,"(G}KUA count = 0 x[5uz)) While GetOperationCount(eID)>count &KS*rHgt? GetOperation eID, count, op u+Q<>>lU If op.Type="ShiftZ" Then eAD uk!Iq DeleteOperation eID,count
@fSBW+ count=count-1 7r4|>F End If mE}@}@( count=count+1 d`+@
_)ea Wend ^*=.Vuqy op.Type = "ShiftZ" 1||\3L/ op.val1 = taq-0.01 lEe<!B$d" op.parent = parID wjeuZNYf AddOperation eID, op x<es1A'u6 8A ;)5! Print "Set pupil diameter = " & pupilDiam gLL8-T[9 c/Ykk7T9-- 'Update AZ Eye subassembly Description zZax![Z eID = FindFullName( "Geometry.Arizona Eye" ) [R~`6 GetEntity eID, entity Btgxzf entity.Description = "Accommodation = " & A & "D" %!X|X,b^O SetEntity eID, entity L d;))e ^Voi4; Update iYk4=l
Print "DONE!" Lm{qFu gx',~ End Sub
:ENdF `nC dRD t.U!T 如果屈光度是4,光瞳直径是4,则会输出如下数据: WQ1~9# o'SZsG Accommodation = 4 Diopters ,p\:Z3{ZH Pupil Diameter = 4 mm [,)G\ Set aqueous humor thickness = 2.81 <X b B; Set anterior lens radius = 10.4 and conic constant = -2.375869 d~F4 Set posterior lens radius = -4.424557 and conic constant = -3.081019 ;"K;D@xzh] Set lens thickness = 3.927 i l5Qo Set lens index of refraction = 1.42672 hE|W%~Jx Set pupil diameter = 4 3\B28m DONE! -0>gq$/N=^
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