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简介 lt{lpH 1BQ0M{& 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。 sI&i{D ~u /aOd 模型 ;)(Sdf[P Xhcn] 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。 b
, juF2 CmEpir{}( Table 1. AZ眼睛模型的定义 DW/1 =3 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. R_Zv'y6 JEWL) 光源 |[S90Gw] k"xGA*B| 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。 2+?T66 g Fe!D%p Qv B7!<{i 图1. 光源和提示信息使用 d<Ggw#}:m 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。 %#~((m1 I=K!)X$ 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。 ;LCTCt` U|gpCy 图2. 字母F光源的设定方法光 `|$'g^eCL E7Ibp79}N 图3. 字母F在视网膜上位置点列图 ~xGoJrF\ 视网膜的散射 iI5+P`sE&J v" }WP34 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。 !^m%O0DT CuH2E>wz Ntb:en!X 图4. 视网膜朗伯散射设定 2w+U$6e C 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。 ^Ye\u1n4 l)4O . * vr=~M? 图5. 视网膜重点采样规格设定 |%
z^N* 脚本 !p9)CjQ " ! Tx&vtq 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: ~+yZfOcw *G9sy_ 图6. 用户对话框的创建与编辑 5%*w<6<_z 图7. 用户对话框编辑器 X) V7bVW 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。 m9in1RI% 余下的脚本计算与屈光度有关的所有参数。 zuSq+pxL@ 4({(i 分析 ,`k_|//}= $ a? 屈光度为4,光瞳直径为4mm,字母F点在视网膜上所成的像。 0}{'C5 :\XI0E 图7. 字母F在视网膜上颜色分析 A{# Nwd> 脚本代码 k1)%.pt% EIjI!0j Option Explicit 'Remove this to enable non-dimensioned variables to be used. zN#*G
i' ='Q{R*u Dim entity As T_ENTITY A /(lK q Dim op As T_OPERATION 'Gx$Bj Dim mat As T_MODELMATERIAL 98RKCc9h Dim A As Double a5@z:i Dim pupilDiam As Double F]UQuOR) Dim eID As Long 3iRA$C-p Dim parID As Long As~(7?]r Dim count As Integer xl(@C*.sC1 Dim taq As Double, Rant As Double, CCant As Double, Rpost As Double, CCpost As Double =pcF:D#+ Dim tlens As Double, nlens As Double G O{.9_2 Dim curv As Double, conic As Double ndink$ Dim ok As Long ~. YWV 5;\gJf Sub Main [U>@,BH K=dR%c( '用户输入对话框 sV/l5]b] Begin Dialog UserDialog 320,126,"Input parameters" ' %GRID:10,7,1,1 N|mJg[j@7 TextBox 220,21,40,21,.TextBox1 'default: 0 S${Zzt" Text 20,21,190,21,"Accommodation (in Diopters):",.Text1,1 Kv37s0|g OKButton 40,91,90,21 ZrO!L_/ CancelButton 190,91,90,21 *4S-z&,.c Text 20,49,190,14,"Pupil diameter (4 mm default):",.Text2,1 Fk"Ee&H)( TextBox 220,49,40,21,.TextBox2 'default: 4 4[yIOs End Dialog :u6JjW[a) Dim dlg As UserDialog Ej=3/RBsV VA] e ok = Dialog (dlg) eg/<[ A: 6KHN&P If ok=0 Then 'cancel button was pressed .pPm~2]z Print "Execution cancelled." /J3ZL[o?Q End p =(@3%k End If b| M3`
mO*^1 'Assign accommodation and pupil diameter & use defaults if field left empty ~YP Jez If dlg.TextBox1 = "" Then <IJu7t> A = 0 'Default accommodation :i~W
}r Else {2&m`Dbm A = CDbl(dlg.TextBox1) yNg9X(U End If 59r_#(uo OFk8 >"| If dlg.TextBox2 = "" Then 'sh~,+g pupilDiam = 4 'Default pupil diameter h.eM
RdlO Else yWDTjY/ pupilDiam = CDbl(dlg.TextBox2) 6at1bQ$ End If 7F^#o-@=J B9R(&<4 Print " " .zg8i_ Print "Accommodation = " & A & " Diopters" Cx<0 H Print "Pupil Diameter = " & pupilDiam & " mm" *\}}Bv+9 |re}6#TgcT ' Calculate new parameters with accommodation \1"'E@+ taq = 0.55 + 2.97 - 0.04*A 'Aqueous thickness p;T{i._iL [XVEBA4GI Rant = 12.0 - 0.4*A 'Radius of anterior lens *&BnF\?m CCant = -7.518749 + 1.285720*A 'Conic constant of anterior lens m: n`g1 P{OAV+cG Rpost = -5.224557 + 0.2*A 'Radius of posterior lens KRAcnY;u CCpost = -1.353971 - 0.431762*A 'Conic constant of posterior lens dU) ]:>Uz =m89z}Ot tlens = 3.767 + 0.04*A 'Lens thickness #Z+i~t{e( Tm}rH]F& nlens = 1.42 + 0.00256*A - 0.00022*A^2 'Lens index of refraction &H}r%%|A kOOGw:/ 'Adjust parameters to account for accommodation N`@NiJ(O; o?L'Pg '************************************************************************* b-ll 'Aqueous thickness (Position of Lens) zGKyN@o '************************************************************************* "@R>J?Cc+ eID = FindFullName( "Geometry.Arizona Eye.Lens" ) {]_uMg#! GetCustomElement eID, entity @"a6fn T>TWU: parID = FindFullName( "Geometry.Arizona Eye" ) [x=jH>Y ~h}Fi ' Delete any shift(s) in z ~5Pb&+<$ count = 0 9.'h^#C While GetOperationCount(eID)>count '* mH*?Y GetOperation eID, count, op ,}oM-B If op.Type="ShiftZ" Then =4V&*go*\ DeleteOperation eID,count ^;!0j9"*: count=count-1 ,B?~-2cCz End If glD cUCF3 count=count+1 lC:k7<0Ji Wend Lbe\@S &'cL%. 'Set new shift in X%z }VA op.Type = "ShiftZ" ojYbR<jn9 op.val1 = taq GjoIm? op.parent = parID infl. AddOperation eID, op ?
WJ> p Print "Set aqueous humor thickness = " & taq-0.55 SJD@&m%?[ #/PA A '************************************************************************* ~wg:!VWA) 'Radius and conic constant of anterior lens zvABU+{jD '************************************************************************* V5+SWXZ eID = FindFullName( "Geometry.Arizona Eye.Lens.Anterior" ) coYij GetConic eID, entity, curv, conic " \I4u{zC RMMd#/A@} SetConic eID, entity, 1/Rant, CCant <: &* Print "Set anterior lens radius = " & Rant & " and conic constant = " & CCant 2,ECYie^ /Mb"V5S(W '************************************************************************* ),%6V5a+E 'Radius and conic constant of posterior lens oIUy -| '************************************************************************* zD?oXs eID = FindFullName( "Geometry.Arizona Eye.Lens.Posterior" ) <ZU=6Hq GetConic eID, entity, curv, conic 3?Y 2L \fr-<5w7 9 SetConic eID, entity, 1/Rpost, CCpost hig2
Print "Set posterior lens radius = " & Rpost & " and conic constant = " & CCpost xsWur(> ] WJI[9@^I~ '************************************************************************* THmb6^ 'Lens thickness (Position of posterior lens surface) SG6sw]x '************************************************************************* ^vG8#A}] 9UvXC)R1 parID = FindFullName( "Geometry.Arizona Eye.Lens" ) Mq';S^ N !TW! ' Delete any z-shift(s) !w&kyW?e count = 0 oK 6(HF'& While GetOperationCount(eID)>count <n3!{w3< GetOperation eID, count, op CI3XzH\IX* If op.Type="ShiftZ" Then J\e+}{ DeleteOperation eID,count AT5aDEb^^ count=count-1 DTWD|M End If iNMx"F0r count=count+1 Tw + Wend asJ)4ema +F
dB ' 'Set new z-shift m3o,@=b op.Type = "ShiftZ" g-Pwp[!qkf op.val1 = tlens z=$jGL op.parent = parID =4 h+
M$2 AddOperation eID, op Bn>8&w/P Print "Set lens thickness = " & tlens &+G"k~% ou
%/l4dC '************************************************************************* b(9FZ]7S 'Lens index of refraction 4H@Wc^K '************************************************************************* .^b;osAU eID = FindMaterial( "Lens" ) ^e+a GetModelMaterial eID, mat ?
w^- D %JlbH8 mat.Nd = nlens O]qU[y+ SetModelMaterial eID, mat "?| > btr Print "Set lens index of refraction = " & nlens 41fJ%f`
G eI@
q|"U '************************************************************************* u ElAnrm 'Pupil diameter q 4V7 '************************************************************************* ?&Pg2]g< eID = FindFullName( "Geometry.Arizona Eye.Pupil.Iris" ) P6MRd/y | ne^imht 'Adjust pupil diameter (trimming volume inner hole) u[{tb JgHM?AWg| SetTrimVolHole eID, pupilDiam/2, pupilDiam/2, 0, 0, "Cylinder" iDf,e Kk$' wY"Q o7 ' Adjust pupil location to just in front of the lens KoS*0U<g6 parID = FindFullName( "Geometry.Arizona Eye" ) bGorH=pb5R eID = FindFullName( "Geometry.Arizona Eye.Pupil" ) Znetzm=0 count = 0 %TsPyiYl While GetOperationCount(eID)>count x"~~l GetOperation eID, count, op f
nI| If op.Type="ShiftZ" Then {W##^L~ DeleteOperation eID,count +*_5tWAc count=count-1 [V}S<Xp End If /<rt1&0 count=count+1 5Vi>%5A>l Wend (!:cen~|[ op.Type = "ShiftZ" E#s)52z=B op.val1 = taq-0.01 t-LG }nv op.parent = parID M?;y\vS?. AddOperation eID, op /y>>JxAEb ~xoF6CF Print "Set pupil diameter = " & pupilDiam wfjnA~1h G}9=) 'Update AZ Eye subassembly Description D$JHs4 eID = FindFullName( "Geometry.Arizona Eye" ) xzx$TUL GetEntity eID, entity w;l<[q?_ entity.Description = "Accommodation = " & A & "D" c*R/]Dn SetEntity eID, entity ^gFqRbuS Q~Z=(rP20 Update z.}[m,oTF Print "DONE!" n6k9~ "? D_8x6`z End Sub *&
m#qEv }@r{?8Ru 如果屈光度是4,光瞳直径是4,则会输出如下数据: 'KPASfC WAn'kA Accommodation = 4 Diopters {?`al5Sz Pupil Diameter = 4 mm 07hF2[i Set aqueous humor thickness = 2.81 yZ!T8"mz{ Set anterior lens radius = 10.4 and conic constant = -2.375869 YX*Qd$chZ Set posterior lens radius = -4.424557 and conic constant = -3.081019 n!qV> k9Y Set lens thickness = 3.927 j;Z?WXWDh Set lens index of refraction = 1.42672 f#Xyoa% Set pupil diameter = 4 $k$4%
7 DONE! 'fL"txW
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