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简介 x-27rGN z ntvKOIh 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。 ]nPfIBoS *nS}1(u] 模型 #J=^CE ASGV3r( 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。 7Z%EXDm4/c Q1f)uwh Table 1. AZ眼睛模型的定义 1i=lJmr 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. ^4MRG6G A c^hZ.qPz 光源 QIl=Ho"c )/4eT\ = 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。 CCoT qZQB"Q.* ?e=3G4N 图1. 光源和提示信息使用 m\*;Fx 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。 hA=.${uIO ;c tPe[5 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。 oZ]^zzoEcg t =LIkwD 图2. 字母F光源的设定方法光 hk*@<ff VT ikLuH 图3. 字母F在视网膜上位置点列图 7Eb |AR 视网膜的散射 pW4O[v` #*;G8yV 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。 (:Y0^ n[[2<s*YJ UP<B>Y1a 图4. 视网膜朗伯散射设定 ( JMk0H3u 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。 r4MPs-}oF DP@F-Q4 ZNfQM&<d 图5. 视网膜重点采样规格设定 y@XE! L 脚本 itYTV?bd cQzUR^oq, 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: G^1 5V'* DXF>#2E^+ 图6. 用户对话框的创建与编辑 Pk?M~{S 图7. 用户对话框编辑器 9 AWFjoXl" 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。 !l9i)6W 余下的脚本计算与屈光度有关的所有参数。 ^7Z#g0{^w _a]0<Vm C0 分析 }[;{@Zn
KP@bz 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 /Fj*sS8 tl6x@%\ 图7. 字母F在视网膜上颜色分析 c)`=wDi 脚本代码 F_I.=zQr yDapl( Option Explicit 'Remove this to enable non-dimensioned variables to be used. #i;y[dQ f|+aa6hN
Dim entity As T_ENTITY +b
sc3 Dim op As T_OPERATION E"<-To Dim mat As T_MODELMATERIAL SD_P=? Dim A As Double Q30TR Dim pupilDiam As Double Zdfruzl&` Dim eID As Long
A)9F_;BY Dim parID As Long ]mR!-Fqj Dim count As Integer 0n/+X[%Ti Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double 9Zj9e Dim tlens As Double, nlens As Double > I>=/i^ Dim curv As Double, conic As Double %n{ue9 Dim ok As Long j&-<e7O= c BcZ@e; Sub Main L3;cAb/ ugV/#v O '用户输入对话框 k0bDEz.X Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 s&d!+-\6_ TextBox 220,21,40,21,.TextBox1 'default: 0 dbG902dR Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 'T+v&M OKButton 40,91,90,21 Lk lD^AJA CancelButton 190,91,90,21 0'Uo3jAB Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 "'3QKeM1 TextBox 220,49,40,21,.TextBox2 'default: 4 *{!E`),FX End Dialog GZ1c~uAu Dim dlg As UserDialog RI2/hrW 7pO/!Lm ok = Dialog (dlg) X1XmaO%A GL-Pir If ok=0 Then 'cancel button was pressed E#n=aY~u- Print "Execution cancelled." N{&Hq4^c End v*JXrB&x End If yvCX
is K''2Jfm 'Assign accommodation and pupil diameter & use defaults if field left empty
QB5,Vfoux If dlg.TextBox1 = "" Then g3| 62uDF A = 0 'Default accommodation :h8-y&; Else [:M Fx6 A = CDbl(dlg.TextBox1) ;;
?OS End If EkpM'j= PiJ>gDx If dlg.TextBox2 = "" Then r7+Ytr pupilDiam = 4 'Default pupil diameter 9jI5bi) Else HhB&vi pupilDiam = CDbl(dlg.TextBox2) R4%}IT^%P End If D[0g0>K !BDJU Print " " =X3Rk)2r Print "Accommodation = " & A & " Diopters" UT%?3}*u" Print "Pupil Diameter = " & pupilDiam & " mm" T4Io+b8$ b *Ca*! ' Calculate new parameters with accommodation ?wVq5^ e taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness P?|>,
\t #k
t+
)> Rant = 12.0 - 0.4*A 'Radius of anterior lens ipD/dx. CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens 1StaQUB \:jJ{bl^A Rpost = -5.224557 + 0.2*A 'Radius of posterior lens dmYgv^t CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens H`OJN. <O3,b:vw tlens = 3.767 + 0.04*A 'Lens thickness oAF#bj_f 6&KcO:}- nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction Qe;R3D=T; 5Ve
T8/7Q 'Adjust parameters to account for accommodation vw*,_f ] p*Fq^ '************************************************************************* R6`,}<A]@ 'Aqueous thickness (Position of Lens) &~"e["gF= '************************************************************************* ,HwOMoP7 eID = FindFullName( "Geometry.Arizona Eye.Lens" ) rnP *} GetCustomElement eID, entity ' 1D1y' W3A9uk6 parID = FindFullName( "Geometry.Arizona Eye" ) r:5u(2 Yu:!l> ' Delete any shift(s) in z H{g&yo count = 0 s
>7(S%#N While GetOperationCount(eID)>count IzlmcP3 GetOperation eID, count, op m`xzvg If op.Type="ShiftZ" Then <KrfM DeleteOperation eID,count ^oDSU7j5, count=count-1 v5 I}a7 End If 2`pg0ciX ( count=count+1 2}6StmE } Wend _)MbvF QFU1l"(qGk 'Set new shift in Id=g!L| op.Type = "ShiftZ" HME`7 dw? op.val1 = taq z+]YB5zK% op.parent = parID B qcFbY AddOperation eID, op bj_oA
i Print "Set aqueous humor thickness = " & taq-0.55 cm`x;[e6l eVRjU '************************************************************************* ]dL#k>$0q 'Radius and conic constant of anterior lens ]]50c '************************************************************************* kz^?!l)X0 eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) oT*qMLdn GetConic eID, entity, curv, conic THmmf_w@ V%JG :'6L SetConic eID, entity, 1/Rant, CCant gUrXaD# Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant x%%OgO+> N _|tw '************************************************************************* 5^Ps(8VbS 'Radius and conic constant of posterior lens tB<|7 '************************************************************************* Y(C-o[-N eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) O_^;wey0}? GetConic eID, entity, curv, conic !T~C =,; oNp(GQ@0 SetConic eID, entity, 1/Rpost, CCpost JQH>{OB Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost 1(jDBP!8 LIfYpn6 '************************************************************************* kGW4kuh)/q 'Lens thickness (Position of posterior lens surface) T*rx5*:o '************************************************************************* s]2_d|Y N.?)s.D( parID = FindFullName( "Geometry.Arizona Eye.Lens" ) =v7%IRP5 []hC* ' Delete any z-shift(s) u9D#5NvGs count = 0 /7uAf{ While GetOperationCount(eID)>count x?RYt4 S GetOperation eID, count, op s'=w/os If op.Type="ShiftZ" Then ObSRd$M DeleteOperation eID,count 3oMhsQz~z count=count-1 $kd9^lj#[ End If |yVveJ count=count+1 { !NXu Wend 8"C[sRhz #?fKi$fS;L 'Set new z-shift WbGN
5?9Q op.Type = "ShiftZ" &z?:s op.val1 = tlens -p[!CI op.parent = parID ;CLOZ{ AddOperation eID, op # GOL%2X Print "Set lens thickness = " & tlens evGUl~</~ ,O`~ D~$ '************************************************************************* v6KRE3:V 'Lens index of refraction agj_l}=gO '************************************************************************* #T$yQ;eQ eID = FindMaterial( "Lens" ) mH/9J
GetModelMaterial eID, mat 'yNS(Bg= ;Miag'7 mat.Nd = nlens =>X" SetModelMaterial eID, mat m.w.h^f$& Print "Set lens index of refraction = " & nlens Uq^-km#a 89\DS!\x9 '************************************************************************* :4/37R(~l8 'Pupil diameter u:M)JG '************************************************************************* s_%KWkS eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) =_Ip0FfK! CZw]@2/JuQ 'Adjust pupil diameter (trimming volume inner hole) aM|;3j1p 2JL\1=k; SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" oe,yCdPs +MyXIWmD ' Adjust pupil location to just in front of the lens 6D/K=- parID = FindFullName( "Geometry.Arizona Eye" ) M6XpauR- eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) !dGSZ|YZ count = 0 ' ?uwUBi While GetOperationCount(eID)>count ^!rAT1(/_ GetOperation eID, count, op 3NSX(gC% If op.Type="ShiftZ" Then dzs(sM= DeleteOperation eID,count {8T/;K@ count=count-1 PgdHH:v) End If 1fqJtP6 count=count+1 cjwc:3
CM Wend bDjm:G op.Type = "ShiftZ" Sc9}WU op.val1 = taq-0.01 ZK5
wZU op.parent = parID &NH[b1NMr AddOperation eID, op <g1=jG:7k /q5!p0fH* Print "Set pupil diameter = " & pupilDiam uYCWsw/ .qS(-7< 'Update AZ Eye subassembly Description KZGy&u
>` eID = FindFullName( "Geometry.Arizona Eye" ) Y+ !z]S/x GetEntity eID, entity 8:fq!m entity.Description = "Accommodation = " & A & "D" c0QKx= SetEntity eID, entity Hv-f :P O ;VS$xnZ Update $[V-M\q Print "DONE!" T!Nv :%>TM/E N End Sub (O"-6`w[ d-`z1' 如果屈光度是4,光瞳直径是4,则会输出如下数据: dU&hM<.| \S0QZQbz/ Accommodation = 4 Diopters 7mA:~- .u Pupil Diameter = 4 mm Kp>fOe'KW Set aqueous humor thickness = 2.81 `y$@zT?j Set anterior lens radius = 10.4 and conic constant = -2.375869 J~|:Q.Rt` Set posterior lens radius = -4.424557 and conic constant = -3.081019 _~bG[lX ! Set lens thickness = 3.927 w5;d/r<q Set lens index of refraction = 1.42672 !OV+=Rwdx Set pupil diameter = 4 @ RP?)*8}& DONE! @1s
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