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简介 T,5]EHea f BukrPsV 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。 ](B+ilr
7hQrL+%q8 模型 <AzvVSA, p'!cGJL 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。 3g)pLW Hh,q)(Wo Table 1. AZ眼睛模型的定义 s)\%%CM 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.
>.0B% 4OC^IS 光源 y&UcTE2;%( Q. @9"&)t 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。 <-FAF:6$@@ 8L^5bJ MoavA
3` 图1. 光源和提示信息使用 '4ftclzL 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 F0qGkMs|f QT&2&#Z 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 R8sj>.I9j g>cp;co9g 图2. 字母F光源的设定方法光 X`ee}C.D_ EH=[!iW ; 图3. 字母F在视网膜上位置点列图 5PqL#Eu`! 视网膜的散射 1=}+NK! u%}zLwMH 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 !Qy%sY wL\OAM6R zT
9"B 图4. 视网膜朗伯散射设定 JgEPzHgx 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 !#Ub*qY1Z 'H0uvvhOp *?:V)!.2z 图5. 视网膜重点采样规格设定 tZB"(\ 脚本 -XRn%4EX? \oA>%+]5 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: B<%cqz@ N2#Wyt8MC 图6. 用户对话框的创建与编辑 GHWi,' mr 图7. 用户对话框编辑器 V:s$V.{! 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。 AY<(`J{ 余下的脚本计算与屈光度有关的所有参数。 MAb*4e# >g+yw1nC 分析 VKqIFM1b 6#hDj_(, 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 g0O~5.f P;4Y%Dq~Qo 图7. 字母F在视网膜上颜色分析 XYj!nx{k, 脚本代码 Se{x-vn?p `\ _>P@qz Option Explicit 'Remove this to enable non-dimensioned variables to be used. :7>oFz GJS3O;2* Dim entity As T_ENTITY |Tv}leJF Dim op As T_OPERATION 'guXdX]Gu Dim mat As T_MODELMATERIAL uGt}H n Dim A As Double
!?)ky `S3 Dim pupilDiam As Double >>bsr#aJ Dim eID As Long ",O |uL Dim parID As Long oN({X/P2j Dim count As Integer v]{F.N Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double VW&EdrR,S Dim tlens As Double, nlens As Double 6Ft?9
B(F: Dim curv As Double, conic As Double }$%j} F{ Dim ok As Long EmG':K( lDsT?yHS`Z Sub Main C-)mP- |8 ad)jw:n '用户输入对话框 (w[#h9j Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 b'r</ncZ TextBox 220,21,40,21,.TextBox1 'default: 0 2i0 .x Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 C fs2tN OKButton 40,91,90,21 UlP2VKM1& CancelButton 190,91,90,21 00SYNG! Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 ^#( B4l! TextBox 220,49,40,21,.TextBox2 'default: 4 8FT]B/^&m End Dialog A:b(@'h Dim dlg As UserDialog f |%II,!3 R`5g# ok = Dialog (dlg) :Oiz|b( cV$an If ok=0 Then 'cancel button was pressed (fA>@5n Print "Execution cancelled." #)r^ZA&E End Sy@)Q[A End If [g<Y,0,J YuXCRw9p; 'Assign accommodation and pupil diameter & use defaults if field left empty lQl!TW"aO If dlg.TextBox1 = "" Then =Gv*yR*]t A = 0 'Default accommodation ~7=eHU.@ Else zsM2R"[X A = CDbl(dlg.TextBox1) ThvgYv--B End If /
f5q9sp8 g?.y7!m If dlg.TextBox2 = "" Then 9epMw-)k pupilDiam = 4 'Default pupil diameter e j,)<* Else mO=A50_&,Q pupilDiam = CDbl(dlg.TextBox2) q@Aw]Kh End If \E(^<Af NiH =T Print " "
?kIyo Print "Accommodation = " & A & " Diopters" )-\C{> Print "Pupil Diameter = " & pupilDiam & " mm" x{O) n FMOO ' Calculate new parameters with accommodation 4aP 96 taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness m]+~F_/ %}IrZrh Rant = 12.0 - 0.4*A 'Radius of anterior lens T>hrKn.!D: CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens tVv/G~( de/oK c Rpost = -5.224557 + 0.2*A 'Radius of posterior lens bN\;m^xfu CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens A`~R\j 2$OV`qy@? tlens = 3.767 + 0.04*A 'Lens thickness v,'k2H w/z o nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction 2YDD`:R
pwH*&YU 'Adjust parameters to account for accommodation =Vm3f^ t`1M}}. '************************************************************************* a&Qr7tTY" 'Aqueous thickness (Position of Lens) =2t=Zyp0Y '************************************************************************* p*j>s\ eID = FindFullName( "Geometry.Arizona Eye.Lens" ) 7W'&v+\ GetCustomElement eID, entity ZO!h!2* %[, R Q">v parID = FindFullName( "Geometry.Arizona Eye" ) -5oYGLS$y3 /X]gm\x7s ' Delete any shift(s) in z 7Ll?#eun count = 0 -%Rw2@vU While GetOperationCount(eID)>count 6B|OKwL GetOperation eID, count, op o~<jayqU If op.Type="ShiftZ" Then IL`LIJ:O DeleteOperation eID,count znB+RiV8 count=count-1 \gu8 ~zK End If
7 }I';>QH count=count+1 :>}7^1I Wend 6oa>\PDy 1Ys)b[: 'Set new shift in (*M0'5 op.Type = "ShiftZ" w~_ycY.e op.val1 = taq b<!' WpY- op.parent = parID \2!. AddOperation eID, op qnHjw Mi Print "Set aqueous humor thickness = " & taq-0.55 cTz@ga;!mI IL:[0q '************************************************************************* oxBTm|j7 'Radius and conic constant of anterior lens YZ]}l%e '************************************************************************* 8[.&ca/[ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) S}fQis GetConic eID, entity, curv, conic S\]9mHJI );T&pm:C> SetConic eID, entity, 1/Rant, CCant (t){o>l Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant ;HBKOe_3 zB`J+r;LU '*************************************************************************
:f:&B8 'Radius and conic constant of posterior lens HE{UgU:tY '************************************************************************* dWi<U4 eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) yZ!~m3Q GetConic eID, entity, curv, conic _k :BY $vK,Gugcx SetConic eID, entity, 1/Rpost, CCpost +1I7K|M Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost [ #ih
o(/ 7NT0]j(w- '************************************************************************* 3-E-\5I 'Lens thickness (Position of posterior lens surface) r;)31Tg '************************************************************************* |Eh2#K0x4G AOkG.u-k parID = FindFullName( "Geometry.Arizona Eye.Lens" ) ~3-"1E>Rgy @-L\c>rqT ' Delete any z-shift(s) W}N7jPO} count = 0 *P5\T4!+d While GetOperationCount(eID)>count k]C k%[d GetOperation eID, count, op 8KN3|) If op.Type="ShiftZ" Then s?s,wdp DeleteOperation eID,count .%dGSDru count=count-1 `\|@w@f|; End If l]~9BPsR count=count+1 x4PzP Wend }A]eC
%sPze] 'Set new z-shift N34-z|"q op.Type = "ShiftZ" WVsj op.val1 = tlens ~NPhVlT op.parent = parID e v0>j4Q AddOperation eID, op IA&V?{OE@I Print "Set lens thickness = " & tlens qdy(C^(fa $m~&| s '************************************************************************* *59| 'Lens index of refraction `1n^~ '************************************************************************* Z m%,L$F*L eID = FindMaterial( "Lens" ) gvc/Z <Y GetModelMaterial eID, mat d>mT+{3 oH&@F@r:+ mat.Nd = nlens @)0 SetModelMaterial eID, mat { `Z~T&}~T Print "Set lens index of refraction = " & nlens -"S94<Y h)fsLzn]Tf '************************************************************************* y$bY
8L 'Pupil diameter 5-ED\- '************************************************************************* ;du},>T$n eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) u{va2n/ d(XOZF 'Adjust pupil diameter (trimming volume inner hole) l`l6Y>c*] CshME\/ SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" [0105l5 !;mn]wR>a ' Adjust pupil location to just in front of the lens N$#~& parID = FindFullName( "Geometry.Arizona Eye" ) t2vm&jk eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) 2}XRqa.| count = 0 Cse`MP While GetOperationCount(eID)>count fMUh\u3 GetOperation eID, count, op ! [1aP, If op.Type="ShiftZ" Then *k; bkd4x DeleteOperation eID,count P7zUf count=count-1 +TA~RCd End If @[?ZwzY:9 count=count+1 vf@j d}? Wend !W8=\:D[ op.Type = "ShiftZ" kr~n5WiAZ op.val1 = taq-0.01 64#Ri!RR} op.parent = parID E9>z.vV
AddOperation eID, op u-y?i` ~E((n Print "Set pupil diameter = " & pupilDiam n"aF#HR?0d XEbVsw 'Update AZ Eye subassembly Description kvbW^pl eID = FindFullName( "Geometry.Arizona Eye" ) mD.6cV GetEntity eID, entity T fkGkVR entity.Description = "Accommodation = " & A & "D" vV$t`PEY SetEntity eID, entity 8x)i{>#i %AtT(G(n Update 6;:D!},'c Print "DONE!" I}o}
#OJ Z2yO /$< End Sub 0Fon`3(^\ CmbgEGIh[a 如果屈光度是4,光瞳直径是4,则会输出如下数据: 4U}J?EB?K 6,jCO@!
Accommodation = 4 Diopters %{4U\4d@' Pupil Diameter = 4 mm 4Eu'_>"a Set aqueous humor thickness = 2.81 Q|{b8K Set anterior lens radius = 10.4 and conic constant = -2.375869 "=
%"@"<) Set posterior lens radius = -4.424557 and conic constant = -3.081019 gg rYf* Set lens thickness = 3.927 F)X`CG ;t Set lens index of refraction = 1.42672 Kw;gQk~R! Set pupil diameter = 4 <z2.A/L DONE! / [49iIzC
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