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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。 Y7;=\/SV
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模型 T[MDjhv '
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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。 p!DOc8a.\e
Table 1. AZ眼睛模型的定义 zx@L sp
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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. \"w+ 4 }
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光源 2w fkXS=~6
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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。 tJmy}.t1
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图1. 光源和提示信息使用 }KT$J G?
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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。 Lcf?VV}
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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。 {a15s6'd
图2. 字母F光源的设定方法光 Y*IKPnPot2
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图3. 字母F在视网膜上位置点列图 u"m TS&
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视网膜的散射 (p] S
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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。 umCmxm r&
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图4. 视网膜朗伯散射设定 ,
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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。 YFW/
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图5. 视网膜重点采样规格设定 N-q6_
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脚本 ^ E.mG>
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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： lCTXl5J5
图6. 用户对话框的创建与编辑 e wWw
图7. 用户对话框编辑器 D Q9aq.;
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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。 uGHM ]"!)
余下的脚本计算与屈光度有关的所有参数。 yXqC
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分析 <PM.4B@
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屈光度为4，光瞳直径为4mm，字母F点在视网膜上所成的像。 ?* ZQ:jH
图7. 字母F在视网膜上颜色分析 2c Sc
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脚本代码 V]m}xZ'?^
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Option Explicit 'Remove this to enable non-dimensioned variables to be used. ,_s.amL3O{
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Dim entity As T_ENTITY _!Pi+l4p/}
Dim op As T_OPERATION J8ScKMUN2
Dim mat As T_MODELMATERIAL Cl3L)
Dim A As Double t=|}?lN<
Dim pupilDiam As Double _~*j=XR s
Dim eID As Long 72_+ b
Dim parID As Long y dj*Jy'
Dim count As Integer 5NhAb$q2Y
Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double W39J)~D^@
Dim tlens As Double, nlens As Double s,AJR
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Dim curv As Double, conic As Double _+H $Pa }?
Dim ok As Long f6nuh &!-
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Sub Main X*w;6 V
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'用户输入对话框 N eP
Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 4'`H H
TextBox 220,21,40,21,.TextBox1 'default: 0 E9Dy)f]#W
Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 E1dhj3+3
OKButton 40,91,90,21 9W_mSum
CancelButton 190,91,90,21 PgHmOs
Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 7=Pj}x)
TextBox 220,49,40,21,.TextBox2 'default: 4 BUV4L5(
End Dialog {d]B+'
Dim dlg As UserDialog 2oOos %0
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ok = Dialog (dlg) c5:0`~5Fn
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If ok=0 Then 'cancel button was pressed 33 wVP}e5
Print "Execution cancelled." fY?:SPR+
End 2(Yg',aMY-
End If &4 #%xg
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'Assign accommodation and pupil diameter & use defaults if field left empty TTbJ9O<43
If dlg.TextBox1 = "" Then dw!Xt@,[g{
A = 0 'Default accommodation i )$+#N
Else
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A = CDbl(dlg.TextBox1) [*I7^h%
End If jTZi<
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If dlg.TextBox2 = "" Then a/H5Y,b>
pupilDiam = 4 'Default pupil diameter 5wE6 gRJ
Else J>< hrZ
pupilDiam = CDbl(dlg.TextBox2) fe"w--v
End If Da!vGr
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Print " " B1s&2{L6K
Print "Accommodation = " & A & " Diopters" %e)vl[:}
Print "Pupil Diameter = " & pupilDiam & " mm" >Q ^ mR
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' Calculate new parameters with accommodation !0 |&f>y
taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness L; A#N9
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Rant = 12.0 - 0.4*A 'Radius of anterior lens z 4` :n.
CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens g\?07@Zd|
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Rpost = -5.224557 + 0.2*A 'Radius of posterior lens Eza^Tbq%j?
CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens ;-l^X%r
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tlens = 3.767 + 0.04*A 'Lens thickness 0(9gTxdB
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nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction e=IbEm{|
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'Adjust parameters to account for accommodation ,KF>@3f
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'************************************************************************* ZCb@!V}=
'Aqueous thickness (Position of Lens) zQt)>Qx_
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eID = FindFullName( "Geometry.Arizona Eye.Lens" ) mo= @Zt
GetCustomElement eID, entity ,?Vxcr
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parID = FindFullName( "Geometry.Arizona Eye" ) dS \n 2Qb
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' Delete any shift(s) in z .i*ja*
count = 0 ";jAH GbO
While GetOperationCount(eID)>count V~5vR`}
GetOperation eID, count, op 7~ZG"^k
If op.Type="ShiftZ" Then m7 XN6zX
DeleteOperation eID,count jGJf[:M&Pm
count=count-1 /X#OX 8gb]
End If RU=g|TL
count=count+1 EG8z&^O x
Wend ;ByCtVm2
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'Set new shift in e%{7CR'~TD
op.Type = "ShiftZ" P9Eh, j0_
op.val1 = taq {_z 6
op.parent = parID '-G,7!.,r%
AddOperation eID, op i12G\Ye
Print "Set aqueous humor thickness = " & taq-0.55 -GQ.B{%G
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'************************************************************************* 4"{g{8
'Radius and conic constant of anterior lens 2"P1 I
'************************************************************************* R iV]SgV 9
eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 73tjDO7d
GetConic eID, entity, curv, conic @cm[]]f'l
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SetConic eID, entity, 1/Rant, CCant Qt^6w}&
Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant w> Ft5"z
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'************************************************************************* !4t%\N6Ib
'Radius and conic constant of posterior lens `$3P@SO"
'************************************************************************* AP=SCq ;
eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) 09G]t1!,
GetConic eID, entity, curv, conic Z vyF"4QN
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SetConic eID, entity, 1/Rpost, CCpost I9U
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Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost dPgA~~
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'************************************************************************* HDu|KW$o1
'Lens thickness (Position of posterior lens surface) lb"T'} q
'************************************************************************* .Dr7YquW
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parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ~IQjQz?
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' Delete any z-shift(s) :b#5 cMUe
count = 0 aIWpgUd`
While GetOperationCount(eID)>count l?;ReK.r
GetOperation eID, count, op :n
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If op.Type="ShiftZ" Then nXxnyom,
DeleteOperation eID,count U2JxzHXZ
count=count-1 "DJ% Yo
End If J=n^&y
count=count+1 T16B2|C"Y
Wend xrJ0
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'Set new z-shift h 'is#X 6:
op.Type = "ShiftZ" O9p^P%U "
op.val1 = tlens lPl JL`e
op.parent = parID Mq6_Q07
AddOperation eID, op i'#%t/ u
Print "Set lens thickness = " & tlens x6 =tS
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'************************************************************************* % g4)f9>
'Lens index of refraction 6|%HCxWO
'************************************************************************* fK=vLcH
eID = FindMaterial( "Lens" ) $>%zNq-F
GetModelMaterial eID, mat |e3YTLsI
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mat.Nd = nlens HsK5 2<
SetModelMaterial eID, mat / pR,l5
Print "Set lens index of refraction = " & nlens 9x9E+DG#(
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'************************************************************************* %,) Xi
'Pupil diameter I]ol[
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'************************************************************************* xtp 5 5"g
eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) UX'tdB
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'Adjust pupil diameter (trimming volume inner hole) 'wTJ X>
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SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" a.AEF P4N
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' Adjust pupil location to just in front of the lens KhbbGdmfS$
parID = FindFullName( "Geometry.Arizona Eye" ) zPb "6%1B
eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) v8A{ q
count = 0 #Cz:l|\ i
While GetOperationCount(eID)>count 2{#=Ygb0
GetOperation eID, count, op hM`*- +Zb
If op.Type="ShiftZ" Then t]pJt
DeleteOperation eID,count .ZH5^Sv$vp
count=count-1 mHC36 ba
End If \Ng[lN
count=count+1 % w6lNl
Wend DZ|/#- k
op.Type = "ShiftZ" k8"[)lDc.
op.val1 = taq-0.01 o/\z4Ri)$
op.parent = parID ~bJ*LM?wOP
AddOperation eID, op YA^g [,
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Print "Set pupil diameter = " & pupilDiam 22m'+3I~Y
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'Update AZ Eye subassembly Description \[x4
eID = FindFullName( "Geometry.Arizona Eye" ) :~9F/Jx
GetEntity eID, entity & |o V\L
entity.Description = "Accommodation = " & A & "D" [ x| {VJ(h
SetEntity eID, entity 93#wU })
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Update h%@#jvh?4
Print "DONE!" V?cUQg hHg
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End Sub aA.TlG@zP
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如果屈光度是4，光瞳直径是4，则会输出如下数据： L"!BN/i_
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Accommodation = 4 Diopters "A9 c]
Pupil Diameter = 4 mm .c.#V:XZ#U
Set aqueous humor thickness = 2.81 x; *KRO
Set anterior lens radius = 10.4 and conic constant = -2.375869 _u`W$EG
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Set posterior lens radius = -4.424557 and conic constant = -3.081019 PK*
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Set lens thickness = 3.927 D<cHa |
Set lens index of refraction = 1.42672 I^6zUVH
Set pupil diameter = 4 Bhrp"l
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DONE! |
