AU2015203775A1 - Electronically controlled fixation light for ophthalmic imaging systems - Google Patents

Abstract

ELECTRONICALLY CONTROLLED FIXATION LIGHT FOR OPHTHALMIC IMAGING SYSTEMS 5 Tibor Juhasz, Guy Holland and Ferenc Raksi An electronically controlled fixation light system is described for ophthalmic systems. The ophthalmic system can include an ophthalmic imaging device that generates an image of a portion of an imaged eye, a fixation light controller that includes an input module, configured to receive an input in relation to the image generated by the ophthalmic imaging device, and a 10 control signal generator that generates an electronic fixation light control signal in response to the received input, and a fixation light source, configured to receive the fixation light control signal, and to generate a fixation light according to the received fixation light control signal. A surgeon can image a portion of an eye with the imaging device, determine a misalignment of the imaged eye relative to the imaging device based on the image, and 15 control the fixation light with an electronic control signal to reduce the determined misalignment.

Description

ELECTRONICALLY CONTROLLED FIXATION LIGHT FOR OPHTHALMIC IMAGING SYSTEMS [00011 The present application is a divisional application from Australian Patent 5 Application No. 2011302161, the entire disclosure of which is incorporated herein by reference. TECHNICAL FIELD [0001a]This patent document relates to systems and techniques for ophthalmic imaging. In more detail, the patent document relates to systems and methods for providing an 10 electronically controlled fixation light for improving a precision of docking of an ophthalmic imaging system to a patient's eye. BACKGROUND [00021 A variety of advanced imaging devices have been developed over the years for ophthalmic imaging, diagnostics and surgery. For some applications, these imaging devices 15 perform best when their optical axis is aligned with the optical axis of the imaged eye. Once the eye is brought into a position aligned with the optical axis of the imaging device, some devices enhance the precision of the imaging by keeping the eye essentially immobilized in this aligned position with a patient interface of an eye-docking system. The alignment of the optical axes is typically achieved by orienting the eye so that its optical axis is parallel to that 20 of the imaging system and then docking the patient interface on the eye in a concentric manner. Therefore, as the precision of the imaging devices improves, the demand for eye docking systems which provide more precise alignment also increases. [00031 Achieving good alignment can be challenging, however, as without feedback and guidance systems the patient module often ends up docking to the eye in an off-center 25 position with the eye's optical axis tilted relative to that of the imaging system. [00041 In some systems, the operator of the imaging device can improve the alignment by adjusting the imaging system, the patient's eye, or both during the docking process. The operator can direct the docking iteratively by directing the patient verbally, manually orienting the eyeball, or adjusting portions of the imaging device, such as its objective or Page 1 of 28 pages gantry. However, the inaccuracy of these approaches can make the docking process quite time consuming and frustrating. [00051 In some systems, such as in some surgical systems using excimer lasers, the alignment is aided by a fixation light. The fixation light can be centered with the optical axis 5 of the imaging system. The patient can be instructed to train his eye on the fixation light, aligning the patient's eye. However, even these fixation light systems have limitations. SUMMARY [0005a] According to a first aspect, the present invention provides an ophthalmic system, comprising: an eye-docking system, including a docking tip; an ophthalmic imaging device, 10 combined with a secondary OCT imaging system, configured to generate an image and an OCT image, of an anterior portion of an imaged eye of a patient; the ophthalmic imaging device comprising an OCT imaging module, configured to computer-generate and to display a reference pattern on the image of the anterior portion of an imaged eye, related to the docking tip of the ophthalmic imaging de vice, and to indicate a misalignment of the imaged 15 eye and the reference pattern, determined from an analysis of the OCT image displayed by the OCT imaging module; a fixation light controller, comprising an input module, configured to receive an input from the system operator in relation to the indicated misalignment, and a control signal generator that generates a fixation light control signal in response to the received input; and a patient-fixation light source, configured to receive the fixation light 20 control signal, and to generate an adjusted fixation light according to the received fixation light control signal. [0005b] According to a second aspect, the present invention provides a method of aligning an eye with an ophthalmic system, the method comprising: providing an eye docking system, including a docking tip; providing an ophthalmic imaging device, combined 25 with a secondary OCT imaging system, and an electronically adjustable patient-fixation light system; positioning a component of the imaging device and an imaged eye of a patient for generating an image and an OCT image of a portion of the imaged eye; generating an image and an OCT image of a portion of the imaged eye; determining a misalignment of the imaged eye relative to the imaging device based on an analysis of the OCT image displayed by an 30 OCT imaging module of the OCT imaging system; indicating the determined misalignment of the imaged eye and a computer-generated reference pattern displayed on the image of the portion of the eye; adjusting a fixation light of the patient-fixation light system by generating Page 2 of 28 pages an electronic control signal according to the determined misalignment to cause the alignment of the imaged eye; and docking the docking tip to the aligned eye. [00061 This patent document discloses fixation light controller systems with improved functionalities. In some systems, the fixation light is simply centered with the optical axis of 5 the imaging device. In such systems, in the typical case of the center of the imaged eye being off the optical axis of the imaging device, even if the patient looks at the fixation light, his or her eye will not be properly aligned with the optical axis of the device. [00071 In some systems, including some YAG lasers and slit lamps, the fixation light is not fixed and thus can be manually adjusted. However, since the adjustment is only 10 mechanical, typically it lacks precision. In addition, such mechanical adjustments can still be quite time consuming and frustrating because of their limited precision. The just described lack of precision of some systems can hinder the performance of these devices, including ophthalmic surgical, imaging and diagnostic systems. [00081 The present patent document discloses fixation light controller systems that offer 15 solutions for the above described problems The disclosed examples and implementations can control a fixation light for an ophthalmic imaging system by non-mechanical control systems. For example, an ophthalmic system can include an ophthalmic imaging device that generates an image of a portion of an imaged eye, a fixation light controller, including an input module, configured to receive an input in relation to the image generated by the ophthalmic imaging 20 device, and a control signal generator that generates a fixation light control signal in response to the received input, and a fixation light source, configured to receive the fixation light control signal and to generate a fixation light according to the received fixation light control signal. [00091 In some implementations, where the ophthalmic imaging device is configured to 25 generate the image essentially optically, the ophthalmic imaging device can include a microscope, an ophthalmic microscope, or a stereo microscope. In some implementations, where the ophthalmic imaging device is configured to generate the image at least in part electronically, the ophthalmic imaging device can include an electronic sensing system that Page 2a of 28 pages s'esacoected imaging ight from the imaged eye, niuding at lea st one of Chare Coupled Device (CC>hOa Coml~plemlliIty Mctali~xidc Semicondutor (CMOS) aray. a pixelaray, and anelectronic sensor arry. The ohthalmicmaging device can also IVclude elconic diphy sstem tiat displaysthe ige of a pori ti of the imaged eye in lation to theceased coected imaging light, finding at ast one of agl Emitting Diod (LED)display a plasma scree'an electronic display a computer display, a iquid Crystal Display,'(LD) screen, a athode Ray Tube &RT) display, vdeo-modue, a vide microscope dispay, a sereo video microscope displaya high definition (i-lDvideo microscope a processior-:sed image system, and an opeumechanical projection psae implementations, the ophthamic imaginge device can include an optical coherence topographic OCT imaging system 10001 In some inplementadonsthe ophthalmic imaging device caninclde an imaging module configured to icate a nisaiignment of' the imaged eye and a reference-cotmponent of the ophthalmic imaging device. inasome imnpiementationsthe reference-conmponent of the imain device can be an jective a patient module, a docking lipaninatrface acat lens a pupila ideng franea reference frame.or an internal lens of the Ophthalici systenih The imaging module can b configured to diplay a reference pattem related to the reference-component tat can assist a system operator to estirnate the misalignment ofthe imaged eye and the reference-omponent of theimaging device. [011 HIn sedeicimpicnentations the ophthalmic imaging deviceacan include an image processor. configured to analyze the iage ofA e porton of the imaged eye and the reference pattetrnand to determine the rmisahgnme it of the imaged eye an d the reference-comnponent of the ia~giugd'evice, and the image noduhe is configurmd to diplay n indication of thec misalignment, determined by the image-processor. [0012] In some implementations, the input module is configured to receive an electronic. miechaical, optical, rsenised input. The input module can include a tuch- pd, a touche screens a joystice an electro-nmechanieal censor, a position setnsor, an opticalI sensora voie prompted actuator, or anelectro -mechanical controller. in some implementationsthe fixation light coure canrinlude at leadt one of a LED arm'a ailacrma screan. electronic display, a computer display, an LCD screen, a video--module, an opto-mechanical projector, a CRT displaya slit-lamp, a proessov-basod image sysetm, and a lighi--soree movable by arn eleto- mechanical actual Perat o 28 pg (OI30] In some implementations th faon light source is configred to display the fiction lght tor a nonimaged eye of the patient, and to move the isplayc fixation Hlt according to the received fixation light control signal toassis a reduction of a misalignment betven the imaged cy and a reference-component of the ophthalmicsystem insme iplementations. the tix'rtion -91 soreisonigrdt geeae the fiatonight for the imaged eye, aod to adjustih generated fxation light according to the received tfa&nn light controlsignalto assist a reduction oft a nicahgnmient between theimaged eye and a referene c e ponent ofthe ophthalmic system. [00141I sonie implemenations method ofC aligning an eye with an ophthamic system can include providing an imaging deice and n electronically adjustable fixation light syst'nposiionnga conponen of the imaging dvNce and an ta ged eye of a pkatiet for generating an image of a portion ofte imaged eye, imagi g a portion of the imaged cov deter A"hig a rnisaignment of theimaged eye reae to the inning device based on rte image. and con hing a fixation eight of the fixation ght system wh an electronic control signal in accordance with the determined misalignment. [0015] In someinmpementaios tihe providing the imaging device can nclude providing aiciroscope.an opithalmic microscope. a stereo microscopea 'idec microscope a Light Emitting Diode (ED) display, a plsma screen, an electronic display, a computer display, a Liquid Qystal isply LC creen, a Cathode Ray Tube (CRT disply, a video-udue, a video microscope dsplar a stereo video microscope display a high definition (HD video tmicroscope a processorobased image system; or an opto-meehanicai projector i some implementations the providing the imaging devie can include providing an optcal colterence tomogiaphic(0C T) system. [001) in some implamentations, the poshioning the concpntmof the inWaging deie can include positioning at least onof an objective a patient module a docking tip, a contact 1ens, a pupiv, aving frame a referenc if me, and internal Iens of rte ophthali system .t a spatial relation w ith a struture of the imaged eye itbi for i mai in some implementationsthe deerrlining the misa ignment can aclude determining at least one "fa lateral misaliginment and a rotational alignment. [0017] In some imlementationste doterminiig the misagnmecnaan include determining the misalignment ith a passive assistance ofteimgng deice the imagg Paer 4 of2Spwags device displaying an i mag of aportion of themaged ecc and a reference pattern. Li sonic implementations, he determining tnisalignmtent can include determining the misalignment with an active assistanceofthe im aing device the imaging device displaying an image of a poWonohe imaged eye, a refeence patten and a misalinment indcato. [001>1 In some implentnations the controlling thefixation light can induae generating the eletronic ctrolsignal with a fiaUtio eight contrller ein thefiAAtion tight controller caninude a touch-pada to"chscen a joystick, an elctr-mechanical sensor.a position sensor, n optical sensor, avice-prormpted actuator, or an elecniecnahanical controller. Lxsonic imnplementations. the generatng. the electronic control signal caninclude generating the electronic controlsignal to cause a fixatiolight sourceto generate theixation light t gide thepatient to reduce the determined misalgmtentt [0019t In someeinrlementamins, the fixataion gh ource can be a LED) arraya plasma screen an electronic display a computer displayan fisplayN a(RT display a video md ea Nslit-lm, a prcesso-baeed image system or a lght-oured movable by an electro mechanical actuator n Asonme inmplementations, he genetitig the electronic control signal can include generating the electronic control signal for at least one ofthe inaged eye and a noni-mag ed ev, i nic irn3emetntatin the deteining them n isalignien a" the controlling the fixation lght can be repeated ieratvely [00201 In sonic impementatios a methd of aligning an eye wth an ophihamic system can include imaging aiportionof a pacedureeye of a patient by an ophthalmic magin' device, displaying the image of the ocdure eye by an imagine module, displaying a reference pattern in relation to the displayed image to indicate-a mIsalignment of the imaged evye nid a reterenceeeent of the ophthalmicystem eceivingafixado light control command by a fixation light controller, anddplaying fixa An lig by a Maon lighi source in response to the fixatonlght control command to assist the parent to reduce the isaliginment. [00211 In sonic implentations the receding the Li ation ight control command cn include receiving the fixation light controlcommand through at east one of a touch-pad, a touch screen a joystick, an electramechanical sensor position senr, an optalsensor, a voiceprompted aetuatt, and an eleetro-mehanicai controlleN In soe implmentationthe displayingth fixation light can ineude displaying th tion ht by at leas one of a LED Pace of{28 arraya'plasma screen ane onic dispiaN a computer display, an IL screen, adeo moedule, anopto-niechanicalprojector, a slitlamp, a prxcessorbased image system, and a htgh-source movable by an electro-mechanicai actmator. In so me imiplem entations, the displaying the fixation light can inlde dispIaytng thefixation light for one of the procedure eye ora t non-procedure eye. BRIEF DESCRIPTION OF THE DRAWINGS [0022] FIG. illustrales a human eye. [00231 FIG. 2 illustrates an ophthalmic imaging apparatus. 100241 FIGS 3AA-C illustrate various misalignments of an eye and an objective. [00251 FIG. 4A llustates an ophthalnie system 100 with a fiation light system 120. 10021 FIG. 45 ihustraes 'a vew of an ophhahic inwagmg device i 10 ad tihe fixation light systern0 Iaen by a patient 100271 FIGS. A-C ilusta an imaging interface of the imaging module 115, a fixation light controlr 130 and a fixation light source 140. [0028j FIG. 6 illustrates a method of openation 200 of the aixtion light system. 100291 FIGS 7A-D illustrate an imAlementation ofthe method of FIG. 6, 0030 FiG. S illustrates a method 300 of aigng a ye ith n ophhmic imaging sys tern. [00311 FIGS. 9AB illustrate a single optical path implenentationof a surgical opihalmic system 100. [00321 FIG 1 istrates an implementaion1O" fan ophthalmic system wib a sttrgieal ophthalmic aipparatus and a fixation light system with asecondary im aging system.s [00331 FIGS IIA-D illustrate an opeation of the opitha imie syst 100" of FIG. 10. Pagc a of 2lpw's DEAILED DESCRITION [00341 FIG. Nihutates a human eye I in sue detail. The eye I includes aconea that receives and re it the incoming ght, an Ir 3. a pupil 4 that provides an opening for the light to enter the inner eye, and lens 5 hat focuses the light on the retina 6 [00351 ImplemerUarins and embodiments inthis patentocument provide a fixation light syEni for phthalmic iiaing'evices frk increasing de precision ofhe alignnt of the imaged eye and the imaging; device [00361 FIG. 2 ilhsraes an ophthalme imaging system10 and its operation A patient can he laid on a supporting bed. An iuaging light source 1 i can shine an imaging light on an imaged cyc i i, A pontin of the inaging light reflected by theimnaged eye iican be collected byan objective 12 an d guided as a collected imaging light 3 to an Opti or opcal s stem The opti I e can guide te collectedimaging light 13 to an imaging module 15. A surgeon or medical professionalcan analyze theimage proided by the imaging module 15 and give instrucons to topa o mo he inaged eye 11 to improve its alignment wil a optical axis of the inaging system 10. I other cases, the surgeon Can niapulat tll Imaged "ye i manually toimprovethealignment These steps can he practiced to prepare.the tmaged eye or dekag a patent interest it Such patent muRaces can be used tar simp imaging th ye i, or for perfoming an ophthalmic surgical procedu. In othr systems, a non conact aging pNroceduean be perrmed after the alignmeti 1P yeother syems, tie alignmen can be followed by a diagnostic procedur a ever the ophthanc icmaging systenr10 can not provide the surgeon with an iiage ofsifficintly high precision b cause the algnment provides is enyapproximat> limiting its accuracy. 100371 FIC 3Ailustrate that after the usethis ini ted precision oihtanic imitg system 10, a rsidual nualignment between the ee I and the ophthalmic inagig system 1i can persist In detaila distal end 20 of the ophthaNic system 10 cant' the obiecuve 12. or contc mode a docking unit a distalip an interface or an applanation modue. In any of these desigs the disnd end 20 can iniude a liotng 21 ti ht support: adital ns 21 An opticalails 2 of the opthanic imaging system 10, typically shared with a optical axis of thedmstal lens 2, can remain misaligned with a n optical axis S of the eve i even after the above linitcdprecision dekng procedure has bec perfored, Pap of "ts [003 FI 3Aillustate: firhmisalignment can be a lateral Insalgnment characterized by a (Arg) vector between the optical axes 8 of the eve and the optical axis 28 of the obiective lying approxiniatelvin the lateral plane perpendicula r to the optical axis 288 [0039] FIG31 illusrats that te misalignment can alsobeaotannalrislignment in geneal the rotatioina alignment can be charactrized by the Q01 Euler angles between the optical axis 8of the eye and the opticalaxis? 8 of the objective 12. in many asesthe misalignment can be a combinaon oralaterl anda rotational misalignment. 0040] FIG C Mustraw that in an iragin g nLtee othe imaging module 15 eithr misalignment can appear as a displacement of the is 3and pupil 4 relative to a trgetg patten 1 7,such asa target circle IThe surgeon Can give verba instructions to the parent to move the maged ey'aii or to manipulate the eye iimacn ally based on this displayed displacement, [o041] However, veal instrtictions can be unclearto an already iorenemd paiem, and maniulating the eye can be cumbersome and nprcise A Mte patient is iy to undo or resist tile actions 0f the surgeon or technicianp [0042] Some ophthnnccstems can utize a fixation light to provide guidance fir the patient However fixation lightdevices still have shorcomingsas discussed above: Some devices provide adjustable fixation ights as an uprovent 1-oweer. even iuch ssten0the location of thesis fypicaly adjusted manually stil resuming in tn adjustment prc ,i lied recision, [0043] FIGS.4-5 llustrate an ophthalmic imaging systen 100 thatcan he used to align the imtaged eve i adhe ophlhnmie system 100 with imp oedgveeisiorn. The ophthalmic system 100 can include an ophthalmic magng device I "O and a fxation light system 10. [00441 FIG. 4A illustrates that the ophthalmic imaging device I t) that can generate an imagr'of a portioi of theimaged eyeIi. The ophthalmic aging device 110 can in elude a imaging light sotre ll that ovides an imaing light fo the imaged eye li The imaging light source ill can be a single light a ring of 4 6 or lig, or a light source waih a continuous ring shape n A objectiee 112 can MiQIlt a fraction of the imaging Hg, returnIed by the imae ye liU and direct it a a collected imaging light 113 to an optic 114. The optnc Parc8at2 fgas 114 can guidethe collected imaging ligh 113towards an imaging module 11 in gneral, the opt 114 can be quite complexincluding' large numberof senses, and mirror The optc can also be multifunetonai, for examph aSo configured to guide a surgicallaser beam to the imarged ye 1i. The imaging nodule 115 can providean image fo-an operator of the imaging syntem 100 via an imagine interfa~cel 100~ -i [00451 in some impglenmenitrions. theophthalmic singing deoice 110 can generate the image essentiailv onciall For example, he ophthalmic imaging device 110 can include a microscope, an ophthalnic microscope, or a stereo microscoe.n An imagng interface of these mitcroscop~es can include the eyepiece of these microscopes. 100461 In some implmentaions he ophthalmic imaing device10 can generate the image at least inart eletrcnically For exampe hthalmic imaging device 110 can include an eleronic sensing system dthaenses the collected imagingight 113 The electronic sensing system caninchude a Chargne-Go upiedDevice (CDgarray, a Coinenar Metal Oxde Semiconductor MOS)rray, a piil-arMay or- n etronic sensor arag to sense the calietd inmaging light 113 100471n these electronic imaging systems theimaging mode 115 can include an electronic dia system a an imaging interfhecc This electronic diSplay can display a eectronic imageof a potion of h imaged eye i i based on the sense ight 1. Ts electronic displayorimaging interface can be, for example a LghtniA Diode it display, a plasma screen. an electronic display a computer disphy, a Liquid rystal Display (CD) scene , Cathode Ray Tube (CR1) display, a video-modle, a ideo M scope displaY a stereo video niroseop dispa, a Highefnition (D videoAmicroscope a processor-based image system, an opto-meehanical projector, or alight-source movable by an electrmechaniac actuator In some impiementaons the elements of teoptical anhe electronic imaging systems can be combined. [0048'] in sonme mplementations, he ophthalmic imaging devie can unclude. an optical cohernce tomographic OCT imagine system. as descrbed in relation to FIGS 940. [00491 FIG. SA ilhstrates that the imaging: nodule I 5 can indicate mialignnent of the naged eye I and a re ferene-component of the ophthalmic imaging device 110 by siultaneously displaying an image porion of the imaged ey'e iiand a eference or targeting pattern 117.such as a target circle, via its imagig interfaie Parc9 of 28g [0050] The refrence-component of the imaging device 10 can be an objective, a patient module, a docking ti, aninteface contact lns, a pupil a vewig fa, a referee frane, an eternal lens of th e ophthalmc system. or any equivalnts. [00511 The location or displyof the targeting patted 117 on be Bed toe reference> componentin effect indicating the position of the referenegcmponent Therefore the simultaneous disply of theuiage portion of the imaged eye 1i and the targeong pattern 117 by the aging module 115 can effectively ast the determaten of the misalgnment of the imaged eve 11i [00521 This assistance can be passive, the imagng module 15 only displaying the image pertion of theiaaged eye Ii nd the reference pattern 1 '?,so tinata system operator can determine a degree of the misaiignient of the imaged eye liand the reference-component f the ophth imic systein 100. [00531 Insome linpiemnenrations.stcht as in electronic iang modules 115, theo 1magn module 1i can acti v assist the determine non offthe mfisalignment of the imaged eye Ii and the reference-component of the ophthaimic intaginh system 100, Such active enmbodimrents can include an image-processor that analyzes the inmage portionof the imaged eyeli andthe target pattemt 117and computes te Tialgne the image module 1 15 then can display an indication of the computed misalignment erg.in the form of an arrow233 (as shown in FIG I),a numerical dedication, a propose' verbal command, or any equivalents [0054] hI addition to the ophthalicicmaging device 110, the ophthalmic imaging system 100 can include the gldtronically contrihlld fixationlgh . tem 120. This elecrtonically controlled fixation lihsysterm 120 can include a fiation light controller 130 ad a fixation light source 1410 100551 FIG. SBilustrate:that the fixation light coat oiler 130 can include an input module 1351 hat can receive an input from a system operator in relation to the nage generated by the inaging module 115. For uxampile a stereo ophthainic mieroscooc of an optical imaging ncldte 115 en present an image of the iii 3 of theaimaged eye Ii i an eyepiece of the stereo microscope and oveday on it a targeting cross ha i 11.In another implementation a ideosplay of a electronic imaging mode 15 an display an image of the pigpil 4 and a circular target patternr117sinultaneovulv, ossibly even actively showing Pa c AMe Sq a qs an arrow to in d thle isaigmmelt. in either embdiment a operatr ofhine imaging sye n100 carmalyze th imageporton of the imaged eye I and the overid targeing pattern 117 to determine a degree of the misalignment of -t imaged eyeL i and the ophthalmic system 100. [00561 in response to the determined nuisahignment the operator ofnhe imaging system 100 can generate an input or comaMnd for he fixation liht system I1 tough the input module 135ofthe fix tion light comroller 130 This input can represent a command regardin how the imaged eye should he moved toredn e th minalganment in a annier descriMed below inn example. if, from the image ofthe aging module 115 the operator determinedhat tie center ofthe imaged eye is millimeters to the ight ofe center of the objetie 11,then the opatos can InpuA command throu h input modu U i5 tN ill ause the patient to movethe imaged eve 2niiineters to the lef to achieve an improved alignment, [00571 The int mod e 135 can be an electronic mechanical, optical, or sensed input module For example, the inpntnodde 15 can be a touch-pa a toucren.ajoyctick, an alectronechanica senor a potIM sensoran opical sensor avoice-promted actuatO, or an ciectroiechanitcalctroller. [00581 FG SB illustrate a rouh pad eAbodiment of h input module 135, wIhee the inpVt cromand is enered by a touring and movement of a finger 9 Ufa system operator. The movement ofM th finger can represent a commandfor the patient how to move th imaged 'ye ii to reduce themisalignment with the ophthalmic system 100 [10591 Once the mmand an entered inothe input module 135, a ntol signal generator of the input modol 135 ca generate a fixation light control signal response It the received command A largevarietyifWell kn eleCric smnal geerators can he utilized for this function. [00601 FIG. SC illustrates that the fixation ight contrler 130 can send the genated fixation ght control ignial to the fixatin ight sure 140 The fiwation light source can receivethe fixatkon light control signal and generate. or display fixation light 145 according to the received fixation light controlsignal1 Paep Li of'tM Pame [0061] The iaon light ouree 140 can in de a LED aa'y a p1sma screen, an akconic display; a cOmaper display an LCD screen, a idemodule, an opto-mechanical projctora sliit-ampaprocessor-ased image system, or a light-source, movable by an electro- mechanicalI actuatcer 100621 IG 4B filutrates that in some implementations the fition ii ght source 140 can gen'rate and disph t fixaion eight 145 fan a nonmaged or control, cv' ithe p Ien 7, The fxatipn iight source 140 canfrst generate and display the ation eight 15. and then move the displayed nation light 145 acordit to the received fixaion ghiontrol signa Since the movementof the control eve i and theimaged eveli closely track each other. as te ontrol eye 1 c is moved by thepatien accordng to e displyedfiaonight 145fte imaged eve I i tesiin a correlated manner. Becauseof this correlation between the movements of the imaged eve 1 and the conmo eve" c the fixation light system120 ca asai1 the reduction of the misalignment of thnaged eye irlitive to the ophthalmic imaging system 110. [00631 Other embodints may simply display the Ation light145 on the fixation light source 140 at a Ication according to the station light contrl signal. instead olng it In enher ofthee embodiments, the patient can he intructed to fov.w the fati light 145 with the control eye l. [00641 FIG B 4 iustratesi he appearace of the ophthalmicsystem 100 fr the patient 7 in some embodiments The left pan uows that the imaged eye i cansee ebetive 112, surrounded by giimaging light sources I 1 The right panel shows that the non imaged/cuntrol eye can ee the fixationlight 1i displayed on the fixation lights oute 140' Ithis embo-imentthe fixation light source 140 cp be an LD seen or an equivaent and the fixt ion ligh145 can he a hight spodisayed on the dark ICD screen 140 [0065] To facitateprocedres on both eves, soni embodiments may include tn fixation light soures 140, one on each side of the objectie 112. [0066] FIG 6 ilustrtes a methd200 for operating the ophthalmic imaging sytem 100. The method 200 can include providing an imagine d e - 2 iDoa and an electronically adustabi fixation ght systm - 2 10bP itioNn a component ofhe imaging device and an imaged eye of a patient fn imaging -20D aging a portionofthe imagede'ye230; Pate oz M pcs determining amisalignment of the inaged eye and the component of the imaging device 240; and controlling a nation light electronically according to thedeteined niis-ali ment [00671 The providingthe imaging deiee 210a can include povding a icroscope an ophthaici microscope, a stereomicroscopeavidemicroscope, a Light nting Dode (LD) displv, a asmna screen n electro display computer display, Liquid Crysw Disp lay LCU) screna Cathode Ray Tube(RTIdplay avdeo-modulea video microscope dipiaa steeo video tmcrosco display , agih definitn HD video microscope a proesobasd imge ) yt"em, an opto-mechanical proctor or an optical C ec o .rphiCisy.tet in some of hese maging devices 10 the obi clive !12 cr captin the colleted aging light 113 retuned by the inmged eye il optic 114 can guide the coiieted imaging light 113 to thc imaging module H5 aud disply in g. by the imaging interface of the imainod 11 [0068]he prvding th-' electronically adjtabie fixationelight system 210b can include providinte fix ton light console 130 and the ation light source 140. 900691 Te positioning 22 can indude positioning at east one of the objective I2 the pjaticnrmodule, the hclkig tip, the cctaet iens, the pupil the viewing framne the refetren ce frameor an interallens of tha ophthalic system to hin up ith astructe of the managed eye it Theositioning 220 can also inc ne moving he imaged eye ito a position stitabie for angn h mgdeye 1i1 The positioning can also include moving both the objective 112 of the ophthalmic imaging device 10fSand the imaged eye i to osiionsitble for imaging the imaged eve mii [070] in sme implemeniationsafer the positioning 2.20 the imaged eyeW k and the imnaging device lt) can Ie close bagt tet in phydcal oorntaet; In others terecan the a partial physical contact that still aluovs for a movement ofthe imaged eye i by either the patient of the sargeoni. [00711 he imaging a perapn of the iaged eye 2.30 caninclude thesurgeon imaging a portion of the irmaged eve i with at least one of a croscope, nnhtha nic stereo microscope, a video microscope, a stereo video microscope, a high definition (l-D) video microscope, or an optical coherence tomographieOC syst Pate 1 A o2f Tals [00721 IG. Iillustrate:nhat in some implementation: the detertnuing the misialignnat 140 can includedetermineat leatone of a dretion and a magnitude of a lateral isalimnent or an angle of rotaton oa rotationalmisaignmentthat remained Per the positionngl220 100731 The determining the misalignmnnt 240 can be performed by the operate of the ophthahnimnaging syst'i 100, such as a surgeon. in sT h implementationstheimagin device 10 can assit the determining 240 passively by displaying an imaged prdon of the imaged eve ii and the refeence or targeting patten l7ninultuneously by the inglg interlace of the imainemodue 115. FIG. 7A lustrates an exampk where t image ) theO iris 3 and pupil 4 of theimaged eye 1i is orlad with a display ofte targeting circle 11 Byana ing the two cerdaid inagtus, the sugeon can determine the misalignmet 100741inicangementatims the imaging device 110an assist he deteunining 240 aciv ely y displaying the imagod portio of the imaged eye i the reference or targeting pattern I and a computed misalignment indiator 23 hy th imaging interface of the imaging module 15. FIG. 7A ilutten example, where the ige of the iris 3 anod pupil 4 of the imaged eye 1i is shown simnitaneouisiy with the targeting circle 17 in addition, the ophthalmic inmaginig :item 100 oan detemindet ma u of the miaignment arid indicate it by displaying a maiignment indicator arrow 233 The misalign eat arrow 233 can for eampe point fromihe center Tv, targeting enr Ic I1l to Hie center of the pil 4, or to the center of toelimbus as deternnd by an inage pocesstnggprotocol. [00751 Thae ntrolling the fixation liht 250 can include generating a electronic control signal according te deterUned misalignment in some implementation the electronic control signal can be generated by operating at leat otm of vtoefooad, a toueh-screen, a joystick, an elect.ri-mechanic.aI sensor, a position sensor an otpncal sensor a oice--pompted actuator or an ecetro-nmechanicai contraoler. [0076j The contrlln the AWMdn ieht50 Can als inhdAgnrtigt e i ci Coaril signto cause the fixation light surce 10 display the fiation lght 145 toguide the patient to reduce the misa ligament between the imaged eye Iiand the nphthahnic imaging systems 110 [00771 FIG, B ilustra~tes that :in an exa mpie the surgeon ay analyze the mage of the imaged eye ii and targeting pattr 17on the aging motdle 1 '5 and determine that th Pay LA Of My'a pupil of the imagd eve li is misalign'd relative to the targeting patem 1 in the uppe-left direction, using tihe imaging interface of the imaging modul 11.5 as a referenae The surgeon' determination may he aided by the niagUment indicator 233. [00781 in responscthe surgeon car decide thatthe fixationIigt 145 should be adjusted or moved to the lower-right direction by the fiation light source 140 to guide the patient to reduce ad compensate this misalgnment ornsondingly dhesurgeon can ceat a fixaton light controconmnand or input to represent the compensating adjustment of the fixton ight 14 In this example, thue Srgeon can mio is finger on a touchnad 35 of the fixation light controller 13) in the lower-ght direction. The input of this fixaton light control command can lead tohe generation of an electronic control signal bythe fix tlion light control 30 that causes the iatio Iige source 140 to move the fixation light 14? in the lower-ih tird on an LCD scren. In other embodiments other type: of movement of thesegeonu si can represent thenecesay compensatng ad justmen such as a movement in the ripper-efdiretion. 100791 FTC 7C illstrates that the above exanpiemovng the surgeonM fine 9 in the Ioe or-right direedon can cause thefixaton iight source 140 to correspondingly adIus the disply of'the fixation light 145 asi e tower-right direction on the LCD screen of rth fixation light source 140. The patient can be instructed follow this adjustment of the fixation 1igh 45 with the ion-imaged country' Ic Te movement of the control eye lc is onowed or ta eked by ite ntovaent of the imaged eye 1 Thereflir the method '00 can reduce te misaligntent of the imaged eye Ii ardSte opihaimic iagin g device 110 [0080 FIG. 7D ilhstrates some aspects of the misalignmentreauctin. Th objectve 112 can include various elements in varidtuaimpimentationsii In some exariplesghe Objective 112 carn include a housing 1 I1 to~ suprt a distallens 11-2 This distal lens 11-2can be the application tin ofthe ophthahmic system 100 in some eases directly making contact xithi theeee Inthese embodirnintsthe above system 100and method 200 can be used toan the distalJ ens 112-2 with the imaged eye li. [00811 In other examples, possibly disposable patient interface 123 can be attached to the objecve 112 Thpatie interface 112W3can include a intact lens or applanatin late 112-4ad a vacuunnkirt A uction sa 112-5. In these enbodimentsthe aboe system 100 Pate 15o MS pa3s and method200 can be used for algning either the contact lens 4 r the dital lens 112-2 4ith the imaged eye li, 100821 FIG 7D illustates that in any othe above embodinents the surgeon can enter a misalignmen-compensang coant i command no the fiation light cntrolier 130. generating an electronic centre signal that cases the fixation ght source 140 to adjust the ian mgh 145 The patient can follow the adjsted atiaonrbght145 withthe conteve ic. eauing the imaged eye ir move accordingly The surgeon typigaly enter control commnands that will cause thepatient to m e his imaged eye Ii to reduce the isalinnt with the ophthalni imaging device 110. 10083] A lateral misalignmen canm be compensated by the patient following th adjied fixation light 145 to moethde ingd eye iatendly by nor in general by the ialignment Vector NzhAr% In other inpiemnem taons the V eral misalignment can be also compensated by the smg keen mondg the objecie iI l with a lateral adjutment a , or ingeneral by (rt I in some as's both the imaged eye i and theojeetive 112 ca be adjusted compensate the lateral mnisaiignmernt together [0084] I yet 4cr embodiments, rotational misalignirntn can be reduced by the patients tbllowing te adjusted fixation light 145 caring the imaged eye to rotate by an angle a, or in general by the Euer angles 4; [00851 Finaly, in some ashes both lateral and rotational iialignment can be present betweenthe itmged eye Ii and the ophthaii system 10a. in such cassthe surgeon ma guide the compens to n of thm oti a n tmian igmen by adestingthe :ainlightn 5an by instructing the patient to flulow the 5:alion lights while laterally moving the objectie 11 to comptensate the lateral mn inmxn [0086] As often the St fion light control commahnd i result in a reduction.of die misaiignment but not in its elininatiet, afte the patient reacte~d to the adjusted fixation light 145, the stgoeencngeeatthe detgemiing a reidualmisaiginment 240 and tire contoling the fixationi light :ith the control signal 250 to further reduce the mis.aignment iteratvivl. Tis ieration can he continued until te misaligttment has been compensated witit a desired precision. Paii6i 4 'ac [0087] As bxforedhe fixation light source 140 can include a Et arraya plasma screen, an electronic displea computer displayan LCD srecn. a vido--modui, a Mitlamp a presor based image systemor a ligt-source movable by an electro mechanical actuator. [0088 FIG 8A illustrates a method of of o thephthalmic g sem 100 describing thesstem' operations. [00891 aligning bimaged eyeii eye with the ophthalmi system 100 can include imaging portion of a procedem eye of a patient by an ophthalmic imagn device 310 displaying the image ofhe Procedure eye by m imagi g module 320; playing a refernce pattern reatio to the displaYd image to indicate a Mnisaigpnw n of the imaged eve and a rcferenceelement of the ohhahic system - 330 receiving a fixation light contol cortmand by a fixation light controller 140; and displaying a fixation light by a fixation light soure in response to the fixation lit control command to ssistine patient t reduce the misalignment 3dO. [0O901 Thea s 30430 have been desrnbed easier in deal fromtevewpoint of the operate r the ophthalmic system 100, suh as the surgeon The recenfi h t night control command 340 can include preceivi ng the fixation light control commandatrough at least one of a tottehpad a touch-sereen. a joystck, an electmo-mechanical sensor, a pondton sensor, an optical sensor, a voie-prompted actuator, or an elctro-meedanicai conrioller. [00911 The displaying the fixation light o5 caninclde displaying the Oiation light by at least of a LED array a plasma scrUean ectroic display computer display, n LCD screen, a vidco-module an opto-mnechanical rjctra slit-lampa procesorbased inagd system, or aligh-source movable by an ieto-mnechanical actuator. [0092.1 he displaying the fixation light 350 can inclUde disp'laying 4the fixation lightftor one of the procedure eve or the non-procedure eye. [00931 FIGS. 9AMilIstate anothernplementation of the ophthalmic system 100' The earlier described functionalities he elements 110-145 can characterize the present implentation of the elements 11043 asc weand will not he repealed here. 100941 o addition, theel nes 1 1-l45' can have fncicaitiesreaed to ti feature that in this implemeation of the imaging system 100 thefixationlight 145 is not displayed via separate fixation light display or source140 fer the control eye Ic Inteadafiation Pat 17O2agcs light controller 130 can aln ectronic fixation light contmlsignal to a fixaton light source 140' that projets a projected fixation Bgt1tdgteoptical pathway of the maging device 1 iAssuch the imaging device 110 andthe nation ligt sysAmn 1 share some elemnte as shown by he doed lines in some impkmetations the projected fixation light 145' can be coupled into the optic 114 that connan adidional adjustable tnrorsto adjns the opicl path ofhe projected fixation ght 145 This coupling can take place between the opti l4adthe imaging modul or somewhere iong thep tic l 4 eg by a m spotter BS, as shown. In other embodiments the projeed fixaton light 145' can have a eparte optil ain or pathway to ausit it path an can be Coupled Lino the OpticaI pathway of the taing device 110 Just before the objev eprector 1121 [00951 FTG. 9B as that in these impienttation the projeccd fixationlight 145 can be projected by the objectivecprojector 112' into the imaged eye i In these cmbodimntthe parent can be instrued to folNe projected fxation light !45' directly by te inaged eYe h to reduce theisannt [00 FO 10 illusrtes other inpiemneaton of these ophthalmic system 100" The earlier described fncionalidies ofthe elements 110-145 can characerrne the preserrt iplementation of theelements 11(0"- 4 a a idn will not he repeated here. [00971 In addition, the client: ii 0"-145 can hae fnnctionalities related to the feature thatthe ophthamicsystem 1004 can incde a secondary imaging device 150. The secondary imaging devce 150 can be. Or exantpe an optical coherence tornographic (O sstem, NumeroOT' aging systems ar kawa including tieeomain OCT stemss and frequency domain OCT systems"vvih a specuomme er yr aswept source Aw wide' ariety of these OCT uyster Can be used ir&the ophthaion sysem 100to achieve ious advantage. The imaging bean for the secondary imaging device 150 can be coupled into te maioptic ; pathway via a beam splitter 31. [0098] Smc impiementatiooft e ophthalmdcsstem 100"can also inchde a pruodure laser 160 to 'nous ophthamic nurical procedures. Furher, someembodinss cant include a patient interface 17 to provjidefirmer connection b~etweent the unaged eye li and the ophthalmic imaagig device application of vacuum suction This patientinface 17 can be analogous to the aduent interface 112 in FIG 7 Patey iof >p~S [0O99] In some imnplementations of he onhthahn ic system 100" he imaging can be pertbrned by the imaging module I in which ease theytem 100 and it; operation an be largely analogus to the earlier described embodiments. [0100j In otherimplementation, though, the seeondary/OCT imaging system 150 can be used to image the imaged leye ii. OCT imaging can be particularly usefu toimage a stn ttre of'teyeetht is not 'isible for an oriftha ie microscope, An exampleis imaging the lens 5 of the eye Becaus of its soft supporting system, the lens 5 is often not concentric with thevible structures of the eye suh as the pupil 4. Further, as the weight f the objective e 112 pressures the eye through the interface 170. the lens 5 can beradditionally displaced and Milted. A he same time angng the ophthalmic system 0n W ith the lens 5 insead of the pu&.il 4 or theimbus can be p articlarly imporanat Juring catara't srgenres where dhe quality of the capsuttomy and oher procedures can be improved by such an align eat, [001011 1i1.11A4dillhstrate an operation of this implementation of the ophtlihle system 100". [00102] FIG, I IAllustrates that the OCT imaging system 150 cnn perform fast Oneimensional t D an such asa line scan 81 N When th lens hon by a dotted line as it may not be d dectly visible by a video microscope15 no deon'entri ith the puil 4, typical a center 82 of the OCT scan does not coincidewith a center 1813 of the lens [roo031 FIG. B illustrate hat in this offcenter ease the OCT image -ofthe lens 5o an OCT imaging module 155 displaying the I Dan along the line 181 can exhibit a partial image 2C of the conea, an image 5a of the anterior capular surface and n image 5 of the posterior capsular surfae. The tilted and of-center position of the capsular surfaces Sa ando can he indicativeothe eer 183 of the lens 5 heing ff the optical axis 28 ofthe im agingsystet 100 and the opaa axis 8 of the ln th IN e livo e optical as 28. Other OCT implementations can generate and display two'-dimen sional (2Dyimrages by rastersanniung the lns5 [001041 FIGS. 110D illutrate that the suren can determine the miaignment of a reference element of the imaging systen11 and the im ged lens5 from the anais of the OCT image shown by the OCT lunging module 155 3Ad then proved anaeogously to th method 200, In particula the surgeon can eter fixatiodn ight controlcmmand through Pag 1 I of M aLs the input module 135 of the fixation light controller 1 30 in accordance with the determined nisaii ntT commind genratc an electronic control signal for the fixation lihi source 140 to adjust te fixati li A ght ht5 s t guides .he patient to mo ve his/her eyes to reduce the isalignnent. [001O5 Wile this specification "ontais mnany specifics the should not be construed as limrunons on the scoe OF the inmetion oof Wha can be claimed bu rrahe as descriptiong of features specific to paticular embodiment. Certain features that arc deswbed in this specification in t conexi fungarte enbodiient:a cn al o be imply renrned in combination ini a single ernbodimient. Converely.various feature: that are described in the context of a singl embodiment can alo be implemented in multiple emlbadimtnts scpamately ore in n suable snbcomLintlion. Moreoveratihough features can he described above as actng in certain combinations and even initially claimed as such, one or me featues from a cAimed combination can in smee cases be ecisd fromithe cOnibination l and the i'ed cobination can he directed to asuhconbination or aridon ofa subcombinaera Pae 2 at' cas

Claims (18)

1. An ophthalmic system, comprising: an eye-docking system, including a docking tip; 5 an ophthalmic imaging device, combined with a secondary OCT imaging system, configured to generate an image and an OCT image, of an anterior portion of an imaged eye of a patient; the ophthalmic imaging device comprising an OCT imaging module, configured to computer-generate and to display a reference pattern on the image of the 10 anterior portion of an imaged eye, related to the docking tip of the ophthalmic imaging device, and to indicate a misalignment of the imaged eye and the reference pattern, determined from an analysis of the OCT image displayed by the OCT imaging module; a fixation light controller, comprising 15 an input module, configured to receive an input from the system operator in relation to the indicated misalignment, and a control signal generator that generates a fixation light control signal in response to the received input; and a patient-fixation light source, configured 20 to receive the fixation light control signal, and to generate an adjusted fixation light according to the received fixation light control signal.

2. The ophthalmic system of claim 1, wherein: 25 the ophthalmic imaging device is configured to generate the image essentially optically, the ophthalmic imaging device comprising at least one of Page 21 of 28 pages a microscope, an ophthalmic microscope, a stereo microscope.

3. The ophthalmic system of claim 1, wherein: the ophthalmic imaging device is configured to generate the image at least in part 5 electronically, the ophthalmic imaging device comprising an electronic sensing system that senses a collected imaging light from the imaged eye, including at least one of a Charge-Coupled Device (CCD) array, a Complementary Metal-Oxide 10 Semiconductor (CMOS) array, a pixel-array, and an electronic sensor array; and an electronic display system that displays the image of a portion of the imaged eye in relation to the sensed collected imaging light, including at least one of a Light Emitting Diode (LED) display, a plasma screen, an electronic display, a computer display, a Liquid Crystal Display (LCD) screen, a Cathode Ray Tube (CRT) 15 display, a video-module, a video microscope display, a stereo video microscope display, a high definition (HD) video microscope, a processor-based image system, and an opto mechanical projector.

4. The ophthalmic system of claim 1, the ophthalmic imaging device comprising: 20 an image-processor, configured to analyze the OCT image of the portion of the imaged eye and the reference pattern; and to determine a measure of the misalignment of the imaged eye and docking tip of the imaging device; and 25 the image module is configured to display an indication of the measure of the misalignment, determined by the image-processor. Page 22 of 28 pages

5. The ophthalmic system of claim 1, wherein: the input module is configured to receive an electronic, mechanical, optical, or sensed input. 5

6. The ophthalmic system of claim 1, the input module comprising: a touch-pad, a touch-screen, a joystick, an electro-mechanical sensor, a position sensor, an optical sensor, a voice-prompted actuator, or an electro-mechanical controller.

7. (Previously amended) The ophthalmic system of claim 1, the patient-fixation light 10 source comprising at least one of: a LED array, a plasma screen, an electronic display, a computer display, an LCD screen, a video-module, an opto-mechanical projector, a CRT display, a slit-lamp, a processor-based image system, and a light-source movable by an electro-mechanical actuator. 15

8. The ophthalmic system of claim 1, wherein: the patient-fixation light source is configured to display the fixation light for a non-imaged eye of the patient; and to move the displayed fixation light according to the received fixation light control 20 signal to assist a reduction of a misalignment between the imaged eye and the docking tip of the ophthalmic system.

9. The ophthalmic system of claim 1, wherein: the patient-fixation light source is configured 25 to generate the fixation light for the imaged eye of the patient; and Page 23 of 28 pages to adjust the generated fixation light according to the received fixation light control signal to assist a reduction of a misalignment between the imaged eye and component docking tip of the ophthalmic system. 5

10. A method of aligning an eye with an ophthalmic system, the method comprising: providing an eye-docking system, including a docking tip; providing an ophthalmic imaging device, combined with a secondary OCT imaging system, and an electronically adjustable patient-fixation light system; positioning a component of the imaging device and an imaged eye of a patient for 10 generating an image and an OCT image of a portion of the imaged eye; generating an image and an OCT image of a portion of the imaged eye; determining a misalignment of the imaged eye relative to the imaging device based on an analysis of the OCT image displayed by an OCT imaging module of the OCT imaging system; 15 indicating the determined misalignment of the imaged eye and a computer generated reference pattern displayed on the image of the portion of the eye; adjusting a fixation light of the patient-fixation light system by generating an electronic control signal according to the determined misalignment to cause the alignment of the imaged eye; and 20 docking the docking tip to the aligned eye.

11. The method of claim 10, wherein the providing the imaging device comprises: providing a microscope, an ophthalmic microscope, a stereo microscope, a video microscope, a Light Emitting Diode (LED) display, a plasma screen, an electronic 25 display, a computer display, a Liquid Crystal Display (LCD) screen, a Cathode Ray Tube (CRT) display, a video-module, a video microscope display, a stereo video microscope display, a high definition (HD) video microscope, a processor-based image system, or an opto-mechanical projector. Page 24 of 28 pages

12. The method of claim 10, wherein the determining the misalignment comprises: determining at least one of a lateral misalignment and a rotational misalignment. 5

13. The method of claim 10, wherein the determining the misalignment comprises: determining the misalignment with an active assistance of the imaging device, the imaging device displaying an image of a portion of the imaged eye, a reference pattern and a misalignment indicator. 10

14. The method of claim 10, wherein the adjusting of the fixation light comprises: generating the electronic control signal with a fixation light controller, wherein the fixation light controller comprises at least one of a touch-pad, a touch-screen, a joystick, an electro-mechanical sensor, a position sensor, an optical sensor, a voice prompted actuator, and an electro-mechanical controller. 15

15. The method of claim 10, wherein the generating the electronic control signal comprises: generating the electronic control signal to cause a patient-fixation light source to generate the fixation light to guide the patient to reduce the determined misalignment. 20

16. The method of claim 15, the patient-fixation light source comprising at least one of: a LED array, a plasma screen, an electronic display, a computer display, an LCD display, a CRT display, a video-module, a slit-lamp, a processor-based image system, and a light 25 source movable by an electro-mechanical actuator. Page 25 of 28 pages

17. The method of claim 15, wherein the generating the electronic control signal comprises: generating the electronic control signal for at least one of the imaged eye and a non imaged eye. 5

18. The method of claim 10, wherein: the determining the misalignment and the controlling the fixation light are repeated iteratively. Page 26 of 28 pages