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简介 X'Q$v~/ < pI2} 人眼光学模型可用来设计眼科用设备,光学系统注定了要与人眼一起使用。本文演示了这样一个模型:Arizona眼睛模型,在Jim Schwiegerling教授的书中有详细描述:《Field Guide to Visual and Ophthalmic Optics》。AZ眼睛模型达到了基于平均临床数据所决定的轴上和轴外像差等级。FRED文件包含了此眼睛模型及几个用来分析它的光源,并包括一个基于想要的屈光度来调整模型的内嵌脚本。 ^~(vP: xA]CtB*o7 模型 Qvs}{h/ @(PYeXdV6& 模型的定义如表1种所示,由半径、圆锥常数、折射率、阿贝数、到下一面的距离等一系列表面组成。一些参数由屈光度(A)来决定。 `h12 } ab@Nd$ Table 1. AZ眼睛模型的定义 S pDVD 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. !<]%V]5[_ au2ieZZ[ 光源 R-J\c+C>W S2K_>kvG)~ 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。 =)m2u2c M d8Jy$,/`? ~fB: >ceD 图1. 光源和提示信息使用 6
k+FTDL 除了“Letter F”之外的所有光源的光线位置设定在了孔径光阑位置处,并增加了pre-propagation distance= -8。尽管光线在光瞳处创建,规定的传输方向相对于光线位置在pre-propagation distance之后。这意味着光束沿着Z轴在眼睛的前面以平行光入射,而不是在光瞳处入射。 ?"PUw3V3lB
wly#| 在往下看是内置的脚本用来修改屈光度,使其为4(250mm),光源“Letter F”在视网膜处生成一个字母为F的图像。绿色的光线聚焦的非常好而红色和蓝色光线有一点的模糊。使用Positions Spot Diagram分析工具来观察最为合适。 E\#hcvP j$^3 图2. 字母F光源的设定方法光 F{ J>=TC {gluK#Qm 图3. 字母F在视网膜上位置点列图 WV!qG6\W 视网膜的散射 }kI-UEn$EP ~WU _u,: 在散射文件中,有一个名为“Retina surface”的72%的反射型朗伯散射,它为视网膜的散射提供了一个粗略的近似。为了模拟来自视网膜的散射,改变自定义元件“Eye ball” 下的视网膜的表面从“halt all” 到”Allow All”。并使几何中“plane”可追迹。 X>EwJ"q# E#r6e+e1Q% *}Zd QJL 图4. 视网膜朗伯散射设定 v0 |A
N 注意在视网膜的表面有散射重点采样规格定义,在“Scatter”标签的底部可获取该信息。“toward pupil”指定散射光朝向光瞳,半角度10度。 ws
Lg6 eIK8J,- I\PhgFt@O 图5. 视网膜重点采样规格设定 V(1Ldl'a 脚本 vGO- a2Z (;P)oB"`C 内置脚本使用对话框显示屈光度和光瞳直径的数值设置。使用FRED Basic脚本创建和使用对话框非常容易。图6显示了如何获取用户自定义对话框,如下图所示: BKfcK>%g Bp6jF2 图6. 用户对话框的创建与编辑 ?`Qw=8]` 图7. 用户对话框编辑器 Z; Xg5 如果“OK”按钮按下,将会核对对话框下面的代码行,如果点击取消则脚本终止。然后输入的参数赋予变量,如果此处是保留为空白,则使用默认值。因此,如果没有值输入并点击“OK”按钮,则脚本是以屈光度为0,光瞳直径为4mm来运行的。 P%f],f 余下的脚本计算与屈光度有关的所有参数。 H1rge< }9t$Cs% 分析 wxVf6` {NXc<0a( 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 w-};\]I aB"W6[ 图7. 字母F在视网膜上颜色分析 LGKkT?fcSC 脚本代码 LEvdPG$) e~=fo#*2?@ Option Explicit 'Remove this to enable non-dimensioned variables to be used. /4+M0P l !YSAQi ;I Dim entity As T_ENTITY ~F^=7oq Dim op As T_OPERATION -}@3,G Dim mat As T_MODELMATERIAL 048BQ Dim A As Double [>::@[ Dim pupilDiam As Double d_gm' Dim eID As Long o0&jel1a Dim parID As Long L B1ui Dim count As Integer kM|akG Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double pbKDtqSnz Dim tlens As Double, nlens As Double :XEr{X Dim curv As Double, conic As Double CUfD[un2D Dim ok As Long YuSe~~F)j >/nS<y> Sub Main QgO@oV* S YOwo\'|= '用户输入对话框 "12.Bi.O"[ Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 S*Un$ngAh TextBox 220,21,40,21,.TextBox1 'default: 0 tKrr5SRb Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 ."l@aE=| OKButton 40,91,90,21 ;H/*%2 CancelButton 190,91,90,21 B5*{85p(u Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 `YAqR?Xj_< TextBox 220,49,40,21,.TextBox2 'default: 4 2-j+-B|i End Dialog J!O5`k*.C Dim dlg As UserDialog HiCNs;t GJai!$v ok = Dialog (dlg) Q\&FuU ]S<eO6z If ok=0 Then 'cancel button was pressed Brr{iBz*" Print "Execution cancelled." ZXljCiNn+\ End ^%-$8sV End If U(]a(k<r G$XvxJ 'Assign accommodation and pupil diameter & use defaults if field left empty Gp'rN}i^ If dlg.TextBox1 = "" Then ;X-~C.7k A = 0 'Default accommodation 1O*5>dkX;% Else yjvzA|(YC A = CDbl(dlg.TextBox1) >'wl)j$ End If "8%B
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5A &!]$# If dlg.TextBox2 = "" Then xCFk1%qf pupilDiam = 4 'Default pupil diameter ))|Wm} Else K#H}=Y A pupilDiam = CDbl(dlg.TextBox2) =i } End If \~d|MP}"F: {[hH:
\ Print " " 5:/
zbt\C Print "Accommodation = " & A & " Diopters" s$css{(ek Print "Pupil Diameter = " & pupilDiam & " mm" z(d@!Cd &$t BD@7 ' Calculate new parameters with accommodation K@Q_q/(%; taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness )(~4fA5j) mv|eEz)r Rant = 12.0 - 0.4*A 'Radius of anterior lens Wz}RJC7p CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens $D
+6=m[ _fha9` Rpost = -5.224557 + 0.2*A 'Radius of posterior lens l-xKfp` CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens J*$u >Lp^QP1gU tlens = 3.767 + 0.04*A 'Lens thickness zQM3n =y dqO!p6 nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction \c3zK|^ |E-/b6G 'Adjust parameters to account for accommodation +gqtW86 >;kCcfS3ct '************************************************************************* YMOy6C 'Aqueous thickness (Position of Lens) -jnx0{/ '************************************************************************* xZW6Hk_ eID = FindFullName( "Geometry.Arizona Eye.Lens" ) P1)f-:; GetCustomElement eID, entity [~9rp]< {i y[8eLg parID = FindFullName( "Geometry.Arizona Eye" ) pV{MW#e ,0%P3 ' Delete any shift(s) in z S/G6NBnbS count = 0 N|K,{
p^li While GetOperationCount(eID)>count L9nv05B GetOperation eID, count, op OY7\*wc: If op.Type="ShiftZ" Then 6*cG>I.Z DeleteOperation eID,count l{F^"_U count=count-1 sc'QNhrW End If u,e'5,`N count=count+1 Yn4c6K Wend Ac;rMwXk# c9imfA+e 'Set new shift in LWE[]1= op.Type = "ShiftZ" H6(kxpOI\ op.val1 = taq ^N}zePy0 op.parent = parID g3Q]W(F%$ AddOperation eID, op qawb9Iud0 Print "Set aqueous humor thickness = " & taq-0.55 }[XzM/t im{'PgiR '************************************************************************* H~E(~fl 'Radius and conic constant of anterior lens {WUW.(^]G '************************************************************************* .4Ob?ZS( eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) 1| "s_m>g GetConic eID, entity, curv, conic w='1uV<6 JR{3n* SetConic eID, entity, 1/Rant, CCant >(5*y=\i Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant Q<W9<&VZe @Aa$k:_ '************************************************************************* Z&FC:4!! 'Radius and conic constant of posterior lens %Z~,F? '************************************************************************* k%-_z}:3V eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) AujvKQ( GetConic eID, entity, curv, conic %"^$$$6% sW!pMkd_ SetConic eID, entity, 1/Rpost, CCpost U;Z6o1G Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost wLwAtjW) Li~(kw3 '************************************************************************* x)0g31 49 'Lens thickness (Position of posterior lens surface) csE 9Ns '************************************************************************* "+3p??h%Rq 'U
',9 parID = FindFullName( "Geometry.Arizona Eye.Lens" ) # D"TY-$.= |S48xsFvq ' Delete any z-shift(s) wHm{4 count = 0 !9=hUpRN While GetOperationCount(eID)>count `$oGgz6ZT GetOperation eID, count, op hZ|*=/3k If op.Type="ShiftZ" Then }M?\BH& DeleteOperation eID,count *O-1zIlp count=count-1 pOP`n3m0 End If N%N% count=count+1 UwOZBF< Wend ?8[,0l:| DpjiE/* 'Set new z-shift %7=B?c| op.Type = "ShiftZ" YW55iyM op.val1 = tlens z`UL)W op.parent = parID H_)\:gTG AddOperation eID, op RM\it"g Print "Set lens thickness = " & tlens K +n [tYly`F '************************************************************************* MMg"G6? 'Lens index of refraction /Am,5X. '************************************************************************* 0<*R 0 eID = FindMaterial( "Lens" ) Z$!>hiz2 GetModelMaterial eID, mat {^>dQ+S x7 {<0=y#@u mat.Nd = nlens &!>
)EHGV SetModelMaterial eID, mat X`bN/sI Print "Set lens index of refraction = " & nlens f)w>V3~w, O8:$sei$ '************************************************************************* am,UUJ+h> 'Pupil diameter )RA$E`!b '************************************************************************* <#AS[Q[N eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) 8CKN^8E OB"Ur-hJ0 'Adjust pupil diameter (trimming volume inner hole) xG sg' ut
z. SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" P2_UQ |9>?{
B\a ' Adjust pupil location to just in front of the lens
fp!Ba parID = FindFullName( "Geometry.Arizona Eye" ) #xL^S9P eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) ,ErJUv count = 0 8a{S* While GetOperationCount(eID)>count ?K,xxH GetOperation eID, count, op &K2J$(.t If op.Type="ShiftZ" Then y<r7_ysi DeleteOperation eID,count USF&; M3 count=count-1 %oVoE2T{@ End If bOR1V\Jr$q count=count+1 gP=(2EVE Wend <=WSX{_D op.Type = "ShiftZ" nXH U|5.I op.val1 = taq-0.01 {pJ{UJKv? op.parent = parID y4* }E AddOperation eID, op sOzmw^7
gC^4K9g Print "Set pupil diameter = " & pupilDiam [/_M!&zz2 <P&~k\BuF{ 'Update AZ Eye subassembly Description !V|i\O|Q2 eID = FindFullName( "Geometry.Arizona Eye" ) UeNa GetEntity eID, entity JU^{!u entity.Description = "Accommodation = " & A & "D" >C,=elM SetEntity eID, entity qK}4r5U "fWAp*nI3t Update N"-</kzV Print "DONE!" Y rq-( &h)G>Sqc End Sub ')C%CAYW cQ kH4>C~ 如果屈光度是4,光瞳直径是4,则会输出如下数据: #$q~ZKB ?VC[%sjwn Accommodation = 4 Diopters >y&Db Pupil Diameter = 4 mm Vgy}0pCl Set aqueous humor thickness = 2.81 s;oDwT1 Set anterior lens radius = 10.4 and conic constant = -2.375869 6zuWG0t Set posterior lens radius = -4.424557 and conic constant = -3.081019 -h=K]Y{` Set lens thickness = 3.927 EC[2rROn\ Set lens index of refraction = 1.42672 Z"spua5 Set pupil diameter = 4 &)F8i#M DONE! +E.}k!y q2Xm~uN`) $`7cs}# QQ:2987619807 P%#WeQ+
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