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简介 f(~N+2} )E>yoUhN 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。 U$& '> %# e(|Z<6 模型 83t/\x,Q P~=yTW 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。 /:(A9b-B 7H< IO` Table 1. AZ眼睛模型的定义 !3Pmjip 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. 'o#oRK{# p'2IlQ\ 光源 jga \Ry=nw Bps%>P~. 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。 mY4pvpZw8 v
x/YWZ :,Y1#_\ 图1. 光源和提示信息使用 d8w3Oz54 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。 !W@mW
5J| 3-{BXht) 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。 PRaVe,5a `Y4K w 图2. 字母F光源的设定方法光 72Y6gcg xwof[BnEZ 图3. 字母F在视网膜上位置点列图 <%S)6cw(3 视网膜的散射 D^US2B kF~(B]W( 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。 8TeOh1\ .
c+m(Pk 7`;sX?R 图4. 视网膜朗伯散射设定 *kFd#b+xB 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。 2WFZ6 9AX}V6\+ @GQfBV|3 图5. 视网膜重点采样规格设定 :1j8!R5 脚本 zH}3J} hDJG.,r 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: P7XZ|Td4* ra T9 图6. 用户对话框的创建与编辑 yT@Aj;X0v 图7. 用户对话框编辑器 &3Zb? 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。 -?)^
hbr 余下的脚本计算与屈光度有关的所有参数。 {jB>]7 nWIZ0Nde' 分析 /h+ W L |du%c`wl 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 3u/JcU-< $e7%>*?m 图7. 字母F在视网膜上颜色分析 _)
x{TnK 脚本代码 P|$n U`qC.s(L Option Explicit 'Remove this to enable non-dimensioned variables to be used. g&xj(SMj-$ 6-_g1vq Dim entity As T_ENTITY %%s)D4sW Dim op As T_OPERATION h2Nt@ Dim mat As T_MODELMATERIAL y%i9 b&gDd Dim A As Double EyA
ny\" Dim pupilDiam As Double H@1'El\9 Dim eID As Long 3&^hf^yg Dim parID As Long 8Re[]bE Dim count As Integer \+R %KA/F Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double Q/4-7 Dim tlens As Double, nlens As Double >S7t Dim curv As Double, conic As Double cj>UxU][eS Dim ok As Long QX<n^W BJux5Nh Sub Main . fja;aG Z&Ob,Ru '用户输入对话框 A
r]*?:4y[ Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 ]{6/6jl TextBox 220,21,40,21,.TextBox1 'default: 0 1DB{"8ov Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ):G%o OKButton 40,91,90,21 =\%ER/ CancelButton 190,91,90,21 mxgT}L0i Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 6
H P66B TextBox 220,49,40,21,.TextBox2 'default: 4 (NLw#)? End Dialog `&D#P% Dim dlg As UserDialog r89AX{: @\ y{q; ok = Dialog (dlg) Z8$BgP _gqqPny4$ If ok=0 Then 'cancel button was pressed 47Z3nl? Print "Execution cancelled." ]!{S2x&" End 0 MK} End If u?`{s88_mF =l43RawAmu 'Assign accommodation and pupil diameter & use defaults if field left empty %jjPs. If dlg.TextBox1 = "" Then u4~+Bc_GL A = 0 'Default accommodation )\Q(=: Else tC'E#2 A = CDbl(dlg.TextBox1) S<i1t[E@W End If 6AJk6W^Z ^5E9p@d"J If dlg.TextBox2 = "" Then IrL%0&*hS pupilDiam = 4 'Default pupil diameter 6NX#=A Else (BLxK)0<" pupilDiam = CDbl(dlg.TextBox2) / rc[HbNg. End If %cSx`^`6j y{@\8B] Print " " ?0t^7HMP Print "Accommodation = " & A & " Diopters" c},pu[nL Print "Pupil Diameter = " & pupilDiam & " mm" (Y)2[j S3Y.+. 0U ' Calculate new parameters with accommodation Wz'!stcp taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness {jO+N+Ez9 (U& Rant = 12.0 - 0.4*A 'Radius of anterior lens <rE>?zvm CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens ]_h3 > mO*.' Gm Rpost = -5.224557 + 0.2*A 'Radius of posterior lens VH]}{i"` CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens kAEq +{h !4a fU: tlens = 3.767 + 0.04*A 'Lens thickness %N-aLw\ &qS%~h%2 nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction CO`)XB6W i1uoYb?4(I 'Adjust parameters to account for accommodation $97O7j@ \~*<[.8~ '************************************************************************* LXo$\~M8G8 'Aqueous thickness (Position of Lens) S&}7XjY '************************************************************************* R)66qRf eID = FindFullName( "Geometry.Arizona Eye.Lens" ) C^"zU>W_ GetCustomElement eID, entity T$lV+[7 ikc1,o parID = FindFullName( "Geometry.Arizona Eye" ) N-upNuv gFp3=s0~ ' Delete any shift(s) in z G~5pMyOR count = 0 Sh!c]r>\Q While GetOperationCount(eID)>count !=:>y WQ GetOperation eID, count, op Ts
!g=F If op.Type="ShiftZ" Then 44*#qLN DeleteOperation eID,count }%Mdf6LS64 count=count-1 !s-A`}
s+ End If eP]y\S*P count=count+1 #S?^?3d Wend by>%}#M C<J*C0vQO 'Set new shift in /GGyM]k3 op.Type = "ShiftZ" O z0-cM8t op.val1 = taq u9@B& op.parent = parID X6
BIZ AddOperation eID, op vSnVq>-q& Print "Set aqueous humor thickness = " & taq-0.55 A.r7 ks &'/"=lK '************************************************************************* U*a#{C7" 'Radius and conic constant of anterior lens h7+"*fN '************************************************************************* ura&9~ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) F[}#7}xjA GetConic eID, entity, curv, conic s-rc0:I &5-1Cd E SetConic eID, entity, 1/Rant, CCant 73X*|g[O Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant n0 l|7:Mk vE)N6Ss '************************************************************************* xK6`|/e 'Radius and conic constant of posterior lens +
-Rf@ '************************************************************************* P{)D_Bi eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) )(G<(eiD GetConic eID, entity, curv, conic @]n8*n m[=SCH-; SetConic eID, entity, 1/Rpost, CCpost #[M^Q
h Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost n3$=& zY\u"
'4 '************************************************************************* }SWfP5D@ 'Lens thickness (Position of posterior lens surface) vy~6]hH '************************************************************************* 5Yv*f: G@DNV3Cc parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ZOfv\(iJ; AHs%?5YTY; ' Delete any z-shift(s) 4|_xz;i count = 0 HVA:|Z19 While GetOperationCount(eID)>count p'LLzc## GetOperation eID, count, op 3q4Zwv0z20 If op.Type="ShiftZ" Then Xd:{.AXW DeleteOperation eID,count &C
MBTY#u count=count-1 ,5zY1C==Ut End If Cl3vp_ count=count+1 R7rM$|n=o Wend Y[L,rc/j CfW#Wk:8J 'Set new z-shift BaIpX<$T op.Type = "ShiftZ" 2T*kmDp op.val1 = tlens kI`HD op.parent = parID SHYekX AddOperation eID, op g"sb0d9 Print "Set lens thickness = " & tlens #tZ!D^GQHq 9)+!*(D '************************************************************************* qGag{E5! 'Lens index of refraction tiGH#~? '************************************************************************* LNJKf6: eID = FindMaterial( "Lens" ) 7a9">:~ GetModelMaterial eID, mat 9K}DmS vVtkB$]L mat.Nd = nlens ,9G'1%z, SetModelMaterial eID, mat Ydsnu Print "Set lens index of refraction = " & nlens Bs0~P 4^ B>E4," '************************************************************************* }2LG9B% 'Pupil diameter H%n/;DW '************************************************************************* 0>j0L8#^p eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) C4E}.``Hm !Yo2P" 'Adjust pupil diameter (trimming volume inner hole) DA=LR pqs!kSJV SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" NUiv"tAY 2A ' Adjust pupil location to just in front of the lens ^4WZ%J#g parID = FindFullName( "Geometry.Arizona Eye" ) Q-h< av9 eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) IrRy1][Qr count = 0 I SZEP8w While GetOperationCount(eID)>count J",Cwk\ GetOperation eID, count, op /b{@'] If op.Type="ShiftZ" Then
rY Puo DeleteOperation eID,count |7|'JTy count=count-1 GKg #nXS End If 9Q(Lnu count=count+1 _Rjbm'kC Wend
XU"G op.Type = "ShiftZ" Y_$!XIJ4 op.val1 = taq-0.01 IH*G7; op.parent = parID g#{7qmM AddOperation eID, op ~yN>9f U g NE"z Print "Set pupil diameter = " & pupilDiam 1 h(n}u pPs TgGai 'Update AZ Eye subassembly Description [D|Uwq eID = FindFullName( "Geometry.Arizona Eye" ) # .&t'"u GetEntity eID, entity )sIzBC entity.Description = "Accommodation = " & A & "D" .gNJY7`b SetEntity eID, entity c;b<z|}z {3os9r, Update 4Vj]bm Print "DONE!" kazgI>"Q8 ,|+{C~Ojx End Sub sn[<Lq \RVfgfe 如果屈光度是4,光瞳直径是4,则会输出如下数据: 3KD:JKn^ r^s$U,e#~ Accommodation = 4 Diopters @(/$;I, Pupil Diameter = 4 mm 1(aib^!B Set aqueous humor thickness = 2.81 ,!AYeVq Set anterior lens radius = 10.4 and conic constant = -2.375869
e'|P^G>g Set posterior lens radius = -4.424557 and conic constant = -3.081019 }+NlYD:qF Set lens thickness = 3.927 _B4N2t$ Set lens index of refraction = 1.42672 ?)qm=mebY Set pupil diameter = 4 B_c-@kl DONE! L!5="s[}
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