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简介 <xOv0B VJ1(|v{D4[ 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。 >_3+s~ 3KFw0(S/ 模型 'BY{]{SL *~b3FLzq 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。 7O6VnKl b'\a
4 Table 1. AZ眼睛模型的定义 sU>!sxW 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. 2,.%]U .yp"6S^b 光源 fAMJFHW WR'm<u 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。 c5~d^ fNz*E|]8& P} =eR 图1. 光源和提示信息使用 moO=TGG;F 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。 # 3{g6[Y nNe`?TS?f 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;"jl% -~z]ut<Z 图2. 字母F光源的设定方法光 -P!_<\q\l B/#tR^R 图3. 字母F在视网膜上位置点列图 s':fv[% 视网膜的散射 rN3i5.*/t 0fc]RkHs" 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。 4
I}xygV V,>_L Op] L#<&T 图4. 视网膜朗伯散射设定 z0ULB?*" 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。 U'IJwGRP q7id?F}3& EA )28]Y. 图5. 视网膜重点采样规格设定 ). +!/x 脚本 -OLXR c= [kc%+j<g 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: n ,<`.^ Mp;yvatO 图6. 用户对话框的创建与编辑 J:M)gh~# 图7. 用户对话框编辑器 ~r~~0|= 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。 \<ohe w 余下的脚本计算与屈光度有关的所有参数。 $)OUOv UloZo?
e` 分析 Iq&S6l <0 N7lWeF 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 -BWkPq! .HTX7mA3 图7. 字母F在视网膜上颜色分析 t(SSrM] 脚本代码 A=X2zm>9 C#]% Option Explicit 'Remove this to enable non-dimensioned variables to be used. xJ"CAg|B -"L)<J@gQ? Dim entity As T_ENTITY %I]?xe6 Dim op As T_OPERATION f3h&K}x Dim mat As T_MODELMATERIAL R#Z1+&=' Dim A As Double hv xvwV1 Dim pupilDiam As Double 5- Q`v/w; Dim eID As Long )N
QtjB$ Dim parID As Long a7G0 Dim count As Integer 4_,l[BhsQG Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double q?C)5( Dim tlens As Double, nlens As Double #UREFwSL Dim curv As Double, conic As Double -C$Z%I7 0 Dim ok As Long lu@#) Y=3:Q%X Sub Main W-Cf#o #&\hgsw/T '用户输入对话框 AR\?bB~`c Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 W%]sI n TextBox 220,21,40,21,.TextBox1 'default: 0 [woR 9azC Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 g0.D36 OKButton 40,91,90,21 \K 01F CancelButton 190,91,90,21 @URLFMFi Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 S EY TextBox 220,49,40,21,.TextBox2 'default: 4 ki6`d? End Dialog }I7/FqrD Dim dlg As UserDialog ?MhRdY Hk-)fl#dr ok = Dialog (dlg) 3mn0 n<:/ X tE If ok=0 Then 'cancel button was pressed ^o't& Print "Execution cancelled." +P6#7.p`Z End f}bUuQrH-! End If }+`W[ h&u MBCA%3z08 'Assign accommodation and pupil diameter & use defaults if field left empty Yt*M|0bL If dlg.TextBox1 = "" Then *?oQ6g(Nz A = 0 'Default accommodation 6wzF6]@O Else Yfy6o6*: A = CDbl(dlg.TextBox1) |0w'+HaE~N End If ]
K7>R0 k>{i_`* If dlg.TextBox2 = "" Then =ox#qg.5 pupilDiam = 4 'Default pupil diameter e4NT Else >
3JU pupilDiam = CDbl(dlg.TextBox2) H<`[,t End If <W,k$|w PK C``+Ki Print " " o]#Q6J Print "Accommodation = " & A & " Diopters" TMG:fg&E~ Print "Pupil Diameter = " & pupilDiam & " mm" G;Y,C<)0k c%)uG _ ' Calculate new parameters with accommodation ;:*o
P(9k taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness }eb%"ZH4| M@Q=!!tQ( Rant = 12.0 - 0.4*A 'Radius of anterior lens 6K P!o CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens VO(Ck\i} U6X~]| o Rpost = -5.224557 + 0.2*A 'Radius of posterior lens ^iubqtT] CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens S^)r,cC *D<S \6= tlens = 3.767 + 0.04*A 'Lens thickness H'I|tPs LH4-b- nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction !U>"H8}dv Xkl^!, 'Adjust parameters to account for accommodation J+\F)k>r O)Nt"k7
b '************************************************************************* sNvT0 'Aqueous thickness (Position of Lens) RYE::[O7 '************************************************************************* |[K7oa~# eID = FindFullName( "Geometry.Arizona Eye.Lens" ) QC <(rx GetCustomElement eID, entity QY+#Vp<` g8XGZW! parID = FindFullName( "Geometry.Arizona Eye" ) +nuv?QB/ ;~]&$2sk ' Delete any shift(s) in z 8tA.d.8 count = 0 NG'VlT While GetOperationCount(eID)>count o9wg<LP GetOperation eID, count, op CG9X3%xO% If op.Type="ShiftZ" Then lha)' DeleteOperation eID,count NH'RU`U) count=count-1 ` N(.10~ End If T|.Q81.NE count=count+1 10#!{].#x Wend ,zXL8T ]Jnf.3 'Set new shift in qsvUJU op.Type = "ShiftZ" h| UT/: op.val1 = taq |B` -chK op.parent = parID 18[f_0@ # AddOperation eID, op iqy}|xAU Print "Set aqueous humor thickness = " & taq-0.55 h!K
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'************************************************************************* e!4akKw4wD 'Radius and conic constant of anterior lens Qmn5umd=?\ '************************************************************************* >.{
..~"K eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) {Y/|7Cl0 GetConic eID, entity, curv, conic Ka_UVKwMro _D,8`na>K SetConic eID, entity, 1/Rant, CCant J+IW Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant $#RD3#=?u do[K-r '************************************************************************* ~|uCZ.;o 'Radius and conic constant of posterior lens On'3K+(_ '************************************************************************* J.<eX=< eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) i[\[xfk GetConic eID, entity, curv, conic xh-[]Jz( ='VIbE@qC SetConic eID, entity, 1/Rpost, CCpost _5`M( ;hL2 Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost :W1,s53 *<Ddn&_ '************************************************************************* )D[ypuM& 'Lens thickness (Position of posterior lens surface) V)@MM2, '************************************************************************* 5ef&Ih.3 =k$d8g
ez parID = FindFullName( "Geometry.Arizona Eye.Lens" ) tjd"05"@: q #p)E=$ ' Delete any z-shift(s) :.35pp,0 count = 0 $AXz/fGV While GetOperationCount(eID)>count {?!hUi+ GetOperation eID, count, op 19N:9;Ixz If op.Type="ShiftZ" Then b]JN23IS2 DeleteOperation eID,count P);Xke count=count-1 8^R>y End If L}21[ N~ky count=count+1 VuPET Wend <khx%<)P :mJM=FeJ 'Set new z-shift z9'0&G L
op.Type = "ShiftZ" <GNOT"z op.val1 = tlens _yoG<qI op.parent = parID QE #$bCw AddOperation eID, op (C3d<a\: Print "Set lens thickness = " & tlens O,>&w5 z5vryhX_Z '************************************************************************* UpIf t=@P 'Lens index of refraction 7S1!|*/
I '************************************************************************* Bjo& eID = FindMaterial( "Lens" ) CYn}wkz GetModelMaterial eID, mat b@X@5SJFW (mD]}{> mat.Nd = nlens %om7h$D=` SetModelMaterial eID, mat B_&PK7vA Print "Set lens index of refraction = " & nlens .lFSFJ ?? l3afuD: '************************************************************************* ua[\npz5 'Pupil diameter !<LS4s; '************************************************************************* qnS7z%H8 eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) z8!u6odu % i4pJIb 'Adjust pupil diameter (trimming volume inner hole) *Qf}4a0 YiJu48J SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" <R(2 9QN P
X0#X=$ ' Adjust pupil location to just in front of the lens 6wd]X-G++ parID = FindFullName( "Geometry.Arizona Eye" ) wMUnZHd{| eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) :I$2[K count = 0 G6,8Xwk While GetOperationCount(eID)>count 1CM1u+<iZ
GetOperation eID, count, op sWC"^ S o If op.Type="ShiftZ" Then ?qbp DeleteOperation eID,count CIDL{i8 count=count-1 KCT8Q!\ End If I;v`o{ count=count+1 V[mQ;:= Wend :A'!u r=\ op.Type = "ShiftZ" &f yFUg op.val1 = taq-0.01 bS'r} op.parent = parID a82mC r AddOperation eID, op xY S%dLE" UBVb#FNF Print "Set pupil diameter = " & pupilDiam ul?BKV+3E } 8P}L@q 'Update AZ Eye subassembly Description ?>y-5B[K/( eID = FindFullName( "Geometry.Arizona Eye" ) V~_nyjrJM GetEntity eID, entity )1vojp
4Za entity.Description = "Accommodation = " & A & "D" ~ YK<T+ SetEntity eID, entity #{M
-3 (*RybKoaA Update -!0LIr:" Print "DONE!" vO_quQ[ . N>R%0m<e End Sub p.9v<I%0 <J)A_Kx[57 如果屈光度是4,光瞳直径是4,则会输出如下数据: LU{Z X*"Kg Accommodation = 4 Diopters *r`Yz} Pupil Diameter = 4 mm 9^^#I~- Set aqueous humor thickness = 2.81 $dP)8_Z2 Set anterior lens radius = 10.4 and conic constant = -2.375869 %D
r?.e Set posterior lens radius = -4.424557 and conic constant = -3.081019 j0~3[dyqU Set lens thickness = 3.927 `X='g96C1 Set lens index of refraction = 1.42672 `0i3"06lr Set pupil diameter = 4 '-IT@} DONE! f}X8|GlBo
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