Pro-Fit Contact Lens Fitting Guide
Contents
1. ccccccccccccceeeeeeceeeeeeeeeeeeenees 11 PEIRAO EIE dd A AR EEE A E A 13 Using Pro Fit to select soft spherical and soft toric lenses eeeeeeeeeeeeeeees 13 Post Fitting COMSIGS LAN OMS ocr cate i aaa eile ares cual 15 FOIOW UID JANALYSIS tucccuaseesseicer A eee eee e DAC ARUN Gy 15 Refitting the Previous Wearer sassaaveecccesaeececsaesauueeudvacceeeceesaaaavevaeeceasaeeeeaavddeeaee 16 Special Lens Fitting Applications yvayewwrnnnrnannrrrrnieeiecreccnsensaannvasvaavoonccediend nits 17 IG ATO CONUS ereere oeiee AEAEE LALALA AARETE ELATERO REEAAAA 17 Proposed Methods for Choosing Diagnostic Lenses ececeeeeeeeeeeeeeeeees 17 Avera g No MEN Od ea aaa oT 17 Apex Value and Size Method sssssssssessnnessseeersrrrrnnrrrnserttrrrrrnnnnrnseerrnrnrrnnen 18 Piggy Back Fitting System cccccceeeeeeeeeceeeeeeeee settee ee eeeeeeeecaaeeeeeeeeeeeeeeeeeeeaas 18 Refractive Surgery ccc EEEE 18 Post SAU AS Yaa acta ee aaa allele al lle Ua 19 Introduction For decades many contact lens fitters have recognized the importance of determining and defining the corneal surface of their patients but have been unable to do so for lack of proper instrumentation To achieve the perfect fit more knowledge of the cornea is needed than what one can glean from central and peripheral keratometric readings using manual or automatic keratometers In the past designing contact lenses using methods and nomograms based on K readings has bee2. Custom RGP Select a Constant Diameter for use in this protocol Next select a stock or manufacturer s RGP lens design as well as the choice of diameter preference Note All Default setups are easily changed in several of the RGP fitting screens Click on Save at the bottom of the screen to add a new protocol to the protocol selection list To delete a previously saved protocol highlight the protocol name and click on the Delete button at the bottom of the screen Click on the Patient Evaluation button to begin the fitting process How to use the Patient Evaluation screen A fitting protocol must first be selected before further information can be entered Keratometric and corneal eccentricity information displayed is derived from the topography data of the eye image exam selected for the fitting process Type in the patient s refraction that will be used for the contact lens power calculation see Figure 2 Remember if plus cylinder was indicated for use in the protocol the refraction will be entered in plus cylinder format However the software will convent all plus cylinder refractions to minus cylinder format standard for contact Wz 7 lens prescription calculations for final power calculations This conversion takes place after exiting the Patient Evaluation screen It is not necessary to enter the plus or minus sign between the spherical component and the cylinder component Vertex distance should also b
3. Selections may be made for type of peripheral curve blend center lens thickness and special edge designs For example a lens that will ride high on the cornea due to an area of superior steepening located when viewing the Color Map may indicate the need for a prism ballast Select Prism Ballast from the Special edge design box and notice another box Prism Ballast Choices will appear below You may specify the amount of prism to be added from a range of 50 Diopters to 3 00 Diopters Special lab instructions may be typed in the Notes box Dispensing information can be typed in the lower right hand box located at the bottom of this form You may select from a list of authorized laboratories from which to order the lenses or type in your own laboratory s name phone and fax numbers Laboratories that have been added will appear in the list the next time you return to this screen The Ordered By and Delivery boxes can be customized for your clinic in the same manner Click on the Print Order button to print a hard copy of the order form for your patient s records or to use to fax directly to the lab How to fit a Manufacturer s Design RGP Lens Upon entering the contact lens fitting software select a protocol on the Patient Evaluation screen Enter the patient s spectacle refraction and select all other fields necessary Select RGP on the right and left eye information boxes Click on the Continue button on the bottom of the
4. The default values for the Absolute view of the fluorescein scale are from zero to 75 microns and have been determined to be the most realistic values for fluorescein simulation in most cases Each eye can be enlarged or zoomed to evaluate the patterns in greater detail Click on the button with the arrow located in the upper right hand corner of each eye to activate the zoom function 11 Reposition Lens button Clicking on this button enables you to view the pan and tilt controls of the software Pro Fit tm the only software package that provides an interactive analysis with automatic or manual lens tilt as well as manual lens positioning Replicating the actual position of the contact lens on the patient s eye image is accomplished by moving the simulated lens as if you are facing the patient right numbers or left numbers in 0 1 mm increments The Pan U D enables movement of the contact lens up numbers or down numbers in 0 1 mm increments to correspond with superior or inferior displacement of the contact lens Click on the Up Down arrows on the right hand side of each box to in Figure 9 crease decrease the numbers then click on the OK button to view the change in the Simulated Fluorescein Display The Tilt controls default to automatic as the system normally computes the best lens tilt angles for any Pan position Tilt is best described in relationship to each individual s topography A lens will tilt in the direct
5. the reflected keratometry image is another measure of whether contact lenses are fitting properly However since the keratometer derives its measurements from a very limited area of the central optical zone of the cornea it is not necessarily the best tool for evaluating effects of contact lenses on corneal topography Computer assisted videokeratography provides a more comprehensive view of the cornea Not only can the clinician determine if simulated K s at the three millimeter zone are within plus or minus 50 diopters of the original readings but the clinician can compare quantitatively readings at the three five and seven millimeter zones by semi meridians By comparing post fitting data to pre fitting data the clinician can determine the presence location and degree of corneal warpage distortion and or apical displacement that may be caused by improperly fit contact lenses This information along with a qualitative evaluation using the EyeSys Color Map illustrates the effect of the contact lens on the patient s corneal topography and provides a more accurate picture of corneal topography changes induced by the wearing of rigid or soft contact lenses On each follow up visit computerized videokeratoscopic imaging is performed and the new data is compared to the prefitting data Most of the display screens can be used for comparative purposes 15 The Difference Map display is useful in checking the cornea for changes that could be ta
6. 0 and 10 5 mm If the greatest area of the graft is steep a diagnostic lens with a steep base 19 curve such as 48 00 diopters and a diameter around 9 0 mm to 9 5 mm should be used After performing a slit lamp evaluation of the initial diagnostic lens the clinician will know whether to go steeper flatter smaller or larger and whether a special lens design will be necessary to help center and stabilize the lens over the graft There are several factors that affect how a lens will position and move over a corneal graft The lens will always attempt to position over the area of greatest steepening If the patient s cornea is steeper in the inferior temporal quadrant the lens will position low and temporal on the cornea In most circumstances it will be necessary to use larger diameters in the range of 9 0 to 10 5 mm as mentioned previously to help center and stabilize the lens over the patient s visual axis The degree of steepness at the graft host junction will directly affect the way the lens positions on the cornea and will dictate which lens design is best suited for the patient It may be necessary to order an orthokeratology type design aspheric lenticular prism ballast cone softperm or piggyback lens design td improve the centering and movement of the lens It should be noted that with the Softperm and or piggyback lens designs these lenses and lens combinations may decrease the amount of oxygen to the cornea For some corneal transplant
7. A Comprehensive Guide to Fitting Contact Lenses with EyeSys Pro Fit Contact Lens Fitting Software 1 Sopr Ilai anith faphe Priel by Beth A Soper COA NCLC This page intentionally left blank A Comprehensive Guide to Fitting Contact Lenses with EyeSys Pro Fit Contact Lens Fitting Software by Beth A Soper COA NCLC EyeSys System 2000 Version 4 0 We wish to thank Linda J Rhodes H F C L S A for her contributions to this contact lens fitting guide Table of Contents MOA COE AEEA EERE T E eini waa naan eeee wena eUnaaaAGORR 4 Accessing ProFit siacunucucecccoucotetasuecesuuastessisiasnnanamieeeeee 4 Acquiring eye images to be used for CL fitting DUrDOSES ccccceccceeeeeeeeeeeeeeees 4 Adjusting the view of the simulated fluorescein pattern cccccceeeeeeeseeeeeeeeeees 5 When trial lenses are recOMMENdeA 0 ccccccceeeeeceeeeeeeeseeseeeeeeeeeeesesaasesseeeees 5 Saving the contact lens fitting information eee eeeeeeeeee eee eeeeeeeeeeeeteeeeeeeeeeeeeees 5 How to set up a fitting protocol ain 5 How to use the Patient Evaluation Screen ssssssssssssssseseseseereerrrereerrrererrrrerereen 6 How to use Pro Fit to fit an RGP lens seseeseeseiseeseieeisieresresresrreresrrerrerrerresreern 7 How to design a Custom RGP IONS ccpeeevcceewereees so canecce wacassseeac seca eS 8 FRCS COG ee Ons a eile i ee lille TE 11 How to fit a Manufacturer s Design RGP Lens
8. Color or Numeric Map is used to determine an initial lens for diagnostic purposes Generally the central three millimeters of the topography is grossly affected by the surgery therefore data at 3 millimeters is of little value in fitting these patients Data from the mid periphery approximately three to four millimeters from geometric center measured by semi meridian or the readings at the 5 mm zone on the Numeric Map 18 are used to determine the base curve of the diagnostic lens For example the radius of curvature in the center of the cornea may read 34 00 diopters while at four millimeters from the center the reading is 44 50 diopters see Figure 15 on page 20 In this case a 44 50 Diopter lens with a 9 0 mm diameter would be the first choice for the diagnostic contact lens If an air bubble formed under the lens the Clinician would need to go to a flatter base curve such as a 40 00 Diopter lens and increase the diameter of the lens to 9 5 or 10 5 millimeters It is necessary to use a large diameter lens when fitting this much flatter to achieve stability and the best centering RGP lenses will usually position over the steepest portion of the cornea If the superior cornea dem onstrates a greater area of steepening the lens will probably want to ride up under the upper lid If the inferior portion of the cornea has a greater area of steepening the lens will ride low It may be necessary to order special lens designs to help center some len
9. Diopter flange could be tried over all diameter 7 5 to 8 5 mm If an aspheric lens design is tried the clinician would select an initial diagnostic lens with a 49 25 Diopter base curve diameter 8 0 to 8 5 mm Usually small central cones can be fit with small diameter lenses starting around 7 5 to 8 8 mm regardless of the lens design If the cone is grossly displaced the same base curve of 49 25 diopters either in the Soper Cone design or an aspheric design should be tried first However the clinician will need a larger diameter somewhere between 8 8 and 9 5 mm and a larger optical zone to insure the patient s field of vision will be adequately covered 17 Apex Value and Size Method A second fitting method utilizes the relative size of the cone and the degree of steepness at the apex of the cone to determine what base curve should be used for the first diagnostic lens With this method the cursor is placed on the steepest reading of the cone and the reading is noted The clinician then moves the cursor 2 5 mm laterally to the right of the cone then 2 5 mm to the left of the cone and records those readings see Figure 14 on page 20 These two peripheral readings are then averaged This average is used to select the initial diagnostic lens For example if the reading nasally 2 5 mm from the steepest reading on the cone is 52 50 diopters and temporarily 59 62 diopters the average is 56 00 Diopters An initial diagnostic lens with a base c
10. Lens Order Form to view the order or to produce a hard copy of the patient s contact lens prescription RGP Order Form The patient s name ID number and today s date appear on the order form automatically The lens parameters determined in the Simulated Fluorescein Display are also automatically displayed on this form Special lab instructions may be typed in the Notes box Dispensing information can be typed in the lower right hand box located at the bottom of this form You may select from a list of authorized laboratories from which to order the lenses or type in your own laboratory s name phone and fax numbers Laboratories that have been added will appear in the list the next time you return to this screen The Ordered By and Delivery boxes can be customized for your clinic in the same manner Click on the Print Order button to print a hard copy of the order form for your patient s records or to use to fax directly to the lab Using Pro Fit to select soft spherical and soft toric lenses Contact lens selection and ordering utilizes an extensive and comprehensive database that is updated on a regular basis The software does NOT recommend a specific lens to best fit the patient as there 13 are hundreds of lens names in the database from which to choose The software WILL calculate a suggested power for the lens Suggested power calculations are based on spherical equivalent for mulas vertex distance compensation and mon
11. When using previously saved exams the patient s name must first be selected from the patient locator screen Highlight the exams to be used for fitting then click on the Display button Click on the Contact Lens button to begin the fitting process Note Contact lens fitting may be performed for either one or both eyes simultaneously Acquiring eye images to be used for CL fitting purposes Proper placement and positioning of the patient before the system is required before acquisition of the eye image Adjust the table so that it is comfortable for the patient Put the patient s forehead on the forehead strap his chin all the way in the chin rest and turn his head slightly in the opposite direction of the eye being examined This allows maximization of the data acquired The patient should be looking directly at the fixation light and should be asked to blink before the image is captured Once the image is acquired care should be taken to properly edit the images of any limbal lines or artifacts Failure to do so may cause the software to calculate very flat RGP lens base curves as limbal lines create a false flat periphery Note Please refer to your EyeSys User s Manual for instructions on editing eye images Adjusting the view of the simulated fluorescein pattern Initial display of simulated fluorescein patterns can be dramatically affected by the brightness and contrast level of the monitor used with the system We suggest after fit
12. alistic values for fluorescein simulation in most cases Each eye can be enlarged or zoomed to evaluate the patterns in greater detail Click on the button with the arrow located in the upper right hand comer of each eye to activate the zoom function Reposition Lens button Clicking on this button enables you to view the pan and tilt controls of the software see Figure 7 Pro Fit is the only software program that provides an interactive analysis with automatic or manual lens tilt as well as manual lens positioning Replicating the actual position of the contact lens on the patient s eye image is accomplished by moving the simulated lens as if you are facing the patient right numbers or left numbers in 0 1 mm increments The Pan U D enables movement of the contact lens up numbers or down numbers in 0 7 mm increments to correspond with superior or inferior displacement of the contact lens Click on the Up Down arrows on the right hand side of each box to Figure 7 increase decrease the numbers then click on the OK button to view the change in the Simulated Fluorescein Display The Tilt controls default to automatic as the system normally computes the best lens tilt angles for any Pan position Tilt is best described in relationship to each individual s topography A lens will tilt in the direction of the steepest part of the cornea This function enables Pro Fit to replicate simulated fluorescein patterns as t
13. ct any other axis to view by simply clicking the left mouse button anywhere on an axis inside the fluores cein pattern The position of the mouse cursor is located by the angle notation located at the bottom of the graph To view the circumference graph click on the button next to the word Circumference The data initially displayed is at the center of the lens thus giving the user a quick read out of the central sagittal depth The clinician may select any radius around which to display the amount of tear film thickness for 360 degrees by clicking on an area with the left mouse button The distance from center is indicated in the lower portion of the graph When there is missing data in the periphery of the eye image the software uses extrapolation and indicates extrapolated data points with red dots on the circumference graph 12 Suggested Parameters This group of controls initially displays the software suggested contact lens parameters The controls allow modification to some of the following BC diopters or millimeters The lens base curve Lens Power Diopter The lens refractive power Diam mm The overall lens diameter Corneal e The eccentricity value of the patient s cornea Axial Edge Lift A display only field for the distance between the edge of the contact lens and the virtual prolongation of the lens base curve The software has determined the base curve based on the sagittal depth previously specified in the fitt
14. e selected when compensation for the spherical com ponent is necessary The software will default to 12 mm of vertex distance for power calculations if one is not selected Visible Iris diameter measurement may also be entered however this value is not used for any contact lens parameter computations The software will default to 12 mm VID Figura A unique feature of this software is calculation of Predicted Residual Astigmatism Predicted Residual Astigmatism or PRA is the amount of uncorrected astigmatism that may be present for a certain lens type This calculation is based upon the patient s spectacle refraction corneal toricity and a lens ability to correct astigmatic errors The software will also calculate changes in power for monovision fits see Figure 3 Monovision is the practice of fitting one eye with a power that corrects for distance vision and one eye that is corrected for the patient s reading vision This is used for patients who normally wear bifocal spectacles and have chosen not to wear bifocal contact lenses Select a power for the Near Add or reading lens and notice the box that appears at the bottom of the screen Indicate if the powers for the lenses are to be calculated for distance vision in both eyes or monovision Next select which eye is to be used for the reading or near lens The clinician should decide if the full reading power or 100 is to be used for final power calculations
15. ein pattern The position of the mouse cursor is located by the angle notation located at the bottom of the graph To view the circumference graph click on the button next to the word Circumference The data initially displayed is at the center of the lens thus giving the user a quick read out of the central sagittal depth The clinician may select any radius around which to display the amount of tear film thickness for 360 degrees by clicking on an area in the simulated fluorescein pattern with the left mouse button The distance from center is indicated in the lower portion of the graph When there is missing data in the periphery of the eye image the software uses extrapolation and indicates extrapolated data points with red dots on the circumference graph Suggested Parameters This group of controls initially displays the software suggested contact lens parameters The controls allow modification to most of the following BC displayed in either diopters or millimeters The lens base curve Lens Power Diopter The lens refractive power Diam mm The overall lens diameter O Z mm The optic zone width PC1 diopters or mm The first peripheral curve curvature PC2 diopters or mm The second peripheral curve curvature PC3 diopters or mm The third peripheral curve curvature Width mm The width of the peripheral curve displayed below each curvature reading Sph e A display only field for the eccentricity value of a sph
16. ent Once the best soft lens has been determined and the lens in on the patient s cornea a videokeratoscopic image is taken of the front surface of the soft lens If the curvature findings and overall topographic findings over the soft lens are suitable simulated K s over the soft lens are used to determine the base curve of the rigid contact lens Particular attention should be paid to the proper fitting of the RGP lens to insure that it will move freely over the surface of the soft lens and position adequately over the patient s visual axis If the lens does not move the effect of two lenses can cause corneal edema and decreased visual acuity Refractive Surgery The term refractive surgery is used here to cover all corneal surgery performed to alter the patient s cornea in an attempt to meet a particular visual need Although there are many of these surgeries being performed everyday not all will be successful as the surgeon or patient may want them to be Surgical manipulation of cornea topography with a poor result can be quite challenging to the contact lens fitter Most clinicians agree that it is best to wait at least four to six months after most refractive surgery before the fitting of contact lenses is to be considered Once the cornea is deemed stable fitting contact lenses on these patients can be made easier using computer assisted videokeratography A videokeratoscopic image of the patient s cornea is first obtained Information from the
17. erical lens zero Corneal e The eccentricity value of the patient s cornea Lens e The eccentricity value of the optic zone of an aspheric contact lens Axial Edge Lift A display only field for the distance between the edge of the contact lens and the virtual prolongation of the lense s base curve Modifications to most of these parameters can be done manually by clicking on the Up Down arrows on the right hand side of each box then clicking on the Recalculate button The simulated fluorescein display will then reflect any operator entered changes Any change made to the base curve of the lens will automatically change the power Reset Fitting Values button Clicking on this button restores the original parameters suggested by software to all fields once a modification has been made 10 Print Clicking on this button will print a hard copy of the fluorescein screens once the screen is exited You may return to either the RGP Selection screen or proceed to the Lens Order Form by clicking on the appropriate buttons located at the bottom of the screen Once a lens design is complete click on the Lens Order Form to view the order or to produce a hard copy of the patient s contact lens prescription RGP Order Form The patient s name ID number and today s date appear on the order form automatically see Figure 9 on page 12 The lens parameters determined in the Simulated Fluorescein Display are also displayed on this form
18. es was the RGP custom design of choice for these patients A 20 micron sagittal depth for desired tear film was selected to use in the fitting protocol 9 2 mm lens diameters were chosen for both lenses The software calculated the following parameters using the patient s topographic information along with the criteria indicated in the fitting protocol Peripheral Edge Patient Base Curve Power Diameter Apical Sag Curves Clearance 1 7 72 43 62 4 37 9 2 20 microns 9 16 11 04 11mm 2 7 64 44 12 4 62 9 2 19 microns 8 85 10 36 10 mm In order to attain the same lens cornea relationship for both patients the software calculated different base and peripheral curves designing custom lenses to fit the unique topography of these patients Due to topographical differences and the higher eccentricity value of his cornea Patient 1 was fit with a flatter lens than Patient 2 The program searched for the closest base curve to achieve the desired apical sag of 20 microns resulting in what is commonly referred to as an on K fit for Patient 1 The software selected a steeper base curve to achieve virtually the same lens cornea relationship for Patient 2 How to design a Custom RGP lens Upon entering Pro Fit select a protocol from the Patient Evaluation screen Enter the patient s spectacle refraction and select all other fields necessary Choose RGP on the right and left eye information boxes Click on
19. has been incorporated in the software but which we are not permitted to disclose to the general public The software applies the same iterative process for calculating the base curve but only selects from the manufacturers available base curves The manufacturer s peripheral curve system is utilized to create the simulated fluorescein display To further illustrate this unique feature of Pro Fit we will fit the left eyes of two patients with a custom designed RGP lens These patients have in common almost identical K readings and very similar spectacle refractions The difference between the two patients is that Patient 1 has a corneal eccentricity value of 54 while Patient 2 has a corneal eccentricity value of 32 We must remember that a sphere has an eccentricity or e value of 0 00 The human cornea is not spherical but ellipsoi dal in shape with eccentricity values ranging from 0 00 to 1 00 The average corneal e value is 50 Therefore the larger the e value of the cornea the flatter that cornea is in the periphery Thus the cornea of Patient 1 flattens more towards the periphery than the cornea of Patient 2 Topographical analysis and clinical evaluation reveal the following Corneal Spectacle Patient Eccentricity Refraction Keratometry Readings 1 54 4 00 1 25x015 43 37x013 44 62x103 2 32 4 00 1 25x165 43 37x162 44 62x72 A spherical base curve with 2 spherical peripheral curv
20. hey actually would appear on the patient s cornea Recalculate button Click on this button when changes have been made to any of the lens parameters to display a new fluorescein pattern for the modified contact lens design Show Color Map button To visually correlate the patient s corneal topography and the simulated fluorescein pattern a color map can also be viewed next to either of the fluorescein maps Click on the Show Color Map button and a normalized color map will appear see Figure 8 Viewing the Color Map is essential when determining where the contact lens will position once it is placed on the patient s eye Figure 8 A contact lens will always attempt to position over the area of greatest steepening thus moving away from a flat area of the cornea When looking at the color map use the Pan function to position the simulated lens over the steepest area of the cornea The simulated fluorescein pattern will change to reflect the new position of the contact lens Once the Color Map is displayed the user may select to overlay different features by clicking on the Color Map Options button Click on OK to close this feature Sagittal Meridian and Circumference Graphs The Sagittal Meridian Graph initially displays the amount of tear film thickness across the flat meridian of the patient s cornea The clinician can select any other axis to view by simply clicking the left mouse button anywhere on an axis inside the fluoresc
21. ing protocol and availability of the appropriate base curve by the manufacturer Note if a base curve is not available to produce the sagittal depth specified in the fitting protocol the software will recommend the closest base curve available from the manufacturer to produce the specified lens cornea relationship Optical zone values and peripheral curve information are not displayed for manufacturer designed lenses as this information is often proprietary and not available to the general public The user has the option of changing the base curve of the suggested lens You will be able to select from only the base curves available for the selected diameter Modifications to the base curve can be achieved manually by clicking on the Up Down arrows on the right hand side of each box then clicking on the Recalculate button The simulated fluorescein display will then reflect any operator entered changes Any change made to the base curve of the lens will automatically change the power Reset Fitting Values button Clicking on this button restores the original parameters suggested by software to all fields once a modification has been made Print Clicking on this button will print a hard copy of the fluorescein screen once the screen is exited You may return to either the RGP Selection screen or proceed to the Lens Order Form by clicking on the appropriate buttons located at the bottom of the screen Once a lens design is complete click on the
22. ion of the steepest part of the cornea This function enables the EyeSys software to replicate simulated fluorescein patterns as they actually would appear on the patient s cornea Recalculate button Click on this button when changes have been made to any of the lens parameters to display a new fluorescein pattern for the modified contact lens design Show Color Map button To visually correlate the patient s corneal topography and the simulated fluorescein pattern a color map can also be viewed next to either of the fluorescein maps Click on the Show Color Map button and a normalized color map will appear Viewing the Color Map is helpful in determining where the contact lens will position once it is placed on the patient s eye A contact lens will always attempt to position over the area of greatest steepening thus moving away from a flat area of the cornea When looking at the color map use the Pan function to position the simulated lens over the steepest area of the cornea The simulated fluorescein pattern will change to reflect the new position of the contact lens Once the Color Map is displayed the user may select to overlay different features by clicking on the Color Map Options button Click on OK to close this feature Sagittal Meridian and Circumference Graphs The Sagittal Meridian Graph initially displays the amount of tear film thickness across the flat meridian of the patient s cornea The clinician can sele
23. king place from one visit to the next This display subtracts the difference in curvature obtained from one exam from a second exam The Difference Map is displayed using a separate normalized scale in half Diopter steps which allows the fitter to assess areas of the cornea that have been affected by the lens Viewing data in this manner can demonstrate that a lens may need only minor modification to the peripheral curve system as opposed to major changes in the overall fitting method or design Once modifications have been made to the lens the cornea can be imaged again and assessment made by viewing the difference Map displays Refitting the Previous Wearer Computerized videokeratography can play a vital role in refitting rigid contact lens wearers who have developed corneal warpage from poorly fitting rigid contact lenses A key function of videokeratography in refitting rigid contact lenses is the system s ability to demonstrate when a cornea is stable Serial viedokeratoscopic images are performed on successive visits until the simulated keratometric readings are stable and the topographic color maps indicate similar scaling and patterns Once stability has been achieved the patient is ready to be refit After the patient has been refit videokeratography allows the clinician to follow and maintain a stable fit by evaluating corneal topography on subsequent visits It is also possible to refit rigid or soft contact lenses without discontinuing
24. m To design a protocol click on the Protocol button located at the bottom of the Patient Evaluation screen see Figure 1 The first step is to give the new protocol a name We suggest using the doctor or clinician s name and the type of RGP lens to be designed Pro Fit includes five back surface designs from which to select Aspheric or spherical base curves can be paired with spherical or aspheric peripheral curves The design selected will be applied to all custom designed lenses utilizing this particular protocol For example Doctor Smith likes to use an aspheric back surface design for some of his patients Type in the name Dr Smith s Asphere in the box next to the label Fitting Protocol Next click on the selection Aspheric Base with 1 Aspheric Peripheral Curve Using the sample fluorescein pattern in the area entitled Lens Cornea Relationship establish the desired sagittal depth for this protocol The software will recommend RGP lens parameters based on these preferences and the lens design This is accomplished through an iterative process where the system calculates the base curve of the optical zone until the desired sagittal depth is achieved between the front surface of the cornea and the back surface of the contact lens For example Dr Smith wants a 20 micron vault for his aspheric lens design Click on the arrow in the steeper direction until you reach the number 20 Click on Recalculate Fluorescein to see the am
25. months post op usually because the patient has become impatient with not being able to see as well as he would like to Most post keratoplasty patients require the fitting of a rigid contact lens due to high degrees of irregular corneal astigmatism Some have very flat grafts in relationship to steeper hosts and others have very steep grafts in relationship to grossly flatter hosts In all of these situations computer assisted videokeratographs are valuable tools in determining the best fit for post keratoplasty patients Data from the simulated K readings and information from the Topographic Color Map is used to choose an initial diagnostic lens The following chart is designed to give the clinician a starting point for choosing a diagnostic lens Simulated K s 34 00 to 49 00 Diopters 42 00 to 49 00 Diopters 42 00 to 70 00 Diopters Suggested Base Curves 38 00 to 40 00 Diopters Standard Fit 48 00 to 60 00 Diopters Suggested Diameters 9 5 to 10 5 mm 9 0 to 10 5 mm 9 0 to 9 5mm For example if the largest area of the graft is flat with a smaller area of steepening the clinician should choose an initial diagnostic lens with a flat base curve and a 10 0 mm diameter If the graft measures between 42 00 diopters in the flat meridian and 44 00 diopters in the steep meridian the patient can quite possibly be fit using standard fitting methods It may be necessary to use a larger diameter of between 9
26. n a process of necessity With the arrival of corneal topography our knowledge of the cornea has greatly increased along with our methods for designing contact lenses Pro Fit EyeSys new contact lens fitting software enables clinicians to fit RGP lenses using topo graphical data and provides access to the most comprehensive soft and soft toric contact lens data base available today Predicted residual astigmatism is calculated for each lens type and these calculations are displayed to assist in selecting the lens to best fit your patients Contributing elements that affect the positioning of the contact lens such as tear dynamics lid tension and asymmetric topography are factors that currently are not taken into consideration However with the ability to replicate the actual position of the contact lens on the cornea using the Pan and Tilt features of this program and by viewing the simulated fluorescein pattern displays clinician time for refits and patient adaptation time is reduced to a minimum Note The fitting methods utilized in the 4 0 version of Pro Fit have been developed to be used with NORMAL EYES Special applications for Keratoconus Penetrating Keratoplasty post refractive surgery abnormal corneal curvatures due to trauma and symmetric astigmatism greater than three diopters will be discussed at the end of this guide Accessing Pro Fit Videokeratograph images must first be acquired before accessing Pro Fit
27. or if a smaller percentage of the near power is to be considered Spherical soft soft toric and RGP lens information can be accessed in this program The best fit for each patient is a lens that has a low or zero PRA How to use Pro Fit to fit an RGP lens After selecting a Protocol and entering refraction information on the Patient Evaluation screen click on the radio buttons next to RGP on both the right and left sides Click on Continue at the bottom of the screen The software will now take you to the RGP Selection screen see Figure 4 A wide variety of RGP fitting philosophies can be encom passed by designating sagittal tear depth and over all lens diameter Corneal eccentricity as well as central corneal radius information is used to design a lens relative to each patient s unique topography while maintaining the fitter s preferred lens cornea relationship specified in his fitting protocol The fitter need only to select the diameter of the lens Figure 3 Figure 4 Figure 5 to view the results of the fit reflected in the simulated fluorescein display Custom designed lens peripheral curves will achieve as close to a 08 mm corneal edge clearance as allowed by each patient s unique topographical information Various manufacturers RGP lens designs can also be accessed in this new program see Figure 5 These designs are composed of proprietary information supplied by the manufacturer that
28. or the selected lens material Once the lenses have been selected for both eyes click on the Lens Order Form button at the bottom of the screen The Soft Lens Order Form can be printed to use as an order form and or to insert into the patient s record see Figure 13 Patient information is automatically printed on the form as well as the Clinic name and address entered in the Protocol screen The telephone and FAX numbers must be entered in the appropriate boxes at this time also Once this information is entered it will become a choice for selection for future ordering The Ordered By box may be customized in the same manner There are three pre programmed choices in the Delivery box however this box can be customized with your own selections too Notes or comments to the lab or dispenser can be typed in the Comments box Click on the Print Order button for a hard copy of this form 14 URRE NRE RID SR IP Fan Rate meenen Aare a he Figure 10 Figure 11 Figure 12 Figure 13 Post Fitting Considerations Follow Up Analysis Clinicians use several criteria for determining whether a rigid or soft contact lens is fitting properly One of those criteria is if corneal measurements have been maintained within certain limits Measurements taken on follow up visits that are within plus or minus 50 diopters of the original keratometry readings are considered acceptable when measured by keratometry The quality of
29. ount of fluorescein created by this vaulting effect Selecting 10 15 microns of rear tear layer approximates an Alignment or parallel fit whereas 18 22 microns will display an Apical Clearance fitting technique The range you may select from is 0 60 microns 5 Clicking on the left or flatter arrow will decrease the sagittal depth while clicking on the right or steeper arrow increases the sagittal depth The slide bar can also be moved achieving the same effect by clicking on the bar and holding the left mouse button until reaching the desired position Note 12 microns of sagittal tear depth creates an approximate one half Diopter tear lens and 25 microns creates an approximate one Diopter tear lens Refractions may be entered in either minus or plus cylinder format Should the clinician choose to enter refractions in plus E cylinder notation the software will automatically convert each Figure 1 entered Rx to minus cylinder format standard for contact lens prescriptions calculations RGP curvature display is indicated by selecting either Radius or Diopter Custom and Manufacturer Lens Preferences can be designated in the Lens Default area Diameters for lens designs will be calculated by selecting either a constant diameter or designated by using a formula of millimeters subtracted from the HVID Horizontal visible Diameter Your preference for custom lens RGP materials can be assigned in the drop down menu under the heading
30. ovison considerations When using the software for toric lens fitting the suggested power of the lens may not always be available for the selected lens name We suggest ordering the CLOSEST lens parameters in this situation or selecting another lens that may provide the exact power needed Upon entering Pro Fit software select a protocol on the Patient Evaluation screen Enter the patient s spectacle refraction and select all other fields necessary Click on either soft spherical or soft toric for one or both eyes Click on the Continue button at the bottom of the screen The contact lens database is sorted by daily wear lenses extended flex wear lenses or you can choose from a combined list of lenses with various wearing options Information located in the toric lens and spherical lens analysis box refers to previously entered refraction information suggested power for lens selection and simulated over refraction power calculations for the suggested power see Figure 10 Lenses may be selected by manufacturer or by the lens name in alphabetical order Selecting the lens name first will automatically fill in the manufacturer s name The software will indicate which base curves are available for that particular lens as well as diameter power and lens color information Should you choose a lens power different from the suggested power the software will now note this as the User Selected Power and recalculate the simulated o
31. patients insufficient oxygen transmission may cause graft rejection When Softperm or piggyback lenses are used these patients should be followed frequently To maximize the amount of oxygen available with piggyback fitting systems both of the lenses should have a high DK value ETA Dentin Tretackonpes Borst Figure 14 Figure 10 Eyesys Eyesys Technologies and EyeSys Software are registered trademarks Pro Fit and Eyesys 2000 Corneal Analysis System are trademarks of EyeSys Technologies Inc Copyright EyeSys Technologies Inc 1995 All Rights Reserved Printed in the U S A 1997 20 This page intentionally left blank lid EyeSys SOFTWARE EyeSys Technologies 800 553 0302
32. r Aspheric and Bi Aspheric lens designs on moderate to advanced cones For any fit to be successful the clinician must be able to identify the type size position and degree of advancement of the cone Although cones can be located any where on the cornea most begin in the inferior temporal region of the cornea Using computer assisted videokeratographs the clinician can determine if a cone exists long before there are clinical signs They can identify the shape of the cone locate the position in relationship to the center or mid line of the cornea determine the degree of steepening and determine where to start with diagnostic lenses Proposed Methods for Choosing Diagnostic Lenses Several methods have been proposed for determining how to choose the best diagnostic lens Two of these methods are as follows Averaging Method Using the topographic Color Map the clinician places the cursor on the steepest area of the cone and records the radius at that point The flattest reading of the cornea is then located and is recorded The average of these two readings is used to select the initial diagnostic lens For example if the steepest reading is 56 37 diopters and the flattest reading is 42 12 Diopter the average of these numbers is 49 25 diopters A diagnostic lens with a 49 25 Diopter base curve is tried on the patient If the majority of the cone is located close to the midline a Soper Cone design lens with a base curve of 49 25 with a 43 00
33. r in time the patient s cornea will stabilize and this reading will become more normal This method of refitting may slow the cornea s ability to stabilize To date there are no statistically significant long term studies using computer assisted videokeratography which demonstrate the time it takes for the cornea to stabilize using this or any other refitting method If this method is used it would be wise to inform the patient that it may take from one month to one year for the cornea to stabilize However using the information from the Map displays and the patient s best corrected acuity with a manifest refraction the clinician can determine when corneal topography has become stable 16 Special Lens Fitting Applications Art and science go hand in hand when it comes to fitting patients who have Keratoconus corneal transplants refractive surgery and other corneal irregularities due to trauma or corneal disorders Although the EyeSys Corneal Analysis System currently does not have a contact lens fitting program to design rigid lenses for these typically very difficult cases analyzing the data produced by the Color Maps can decrease patient chair time and reduce the number of diagnostic lenses necessary to achieve a good fit Keratoconus Current methods of fitting rigid contact lenses on patients with Keratoconus involve the use of standard design lenses on patients with incipient cones and the use of either the Soper Cone McGuire Cone o
34. screen On the RGP Selection screen click next to Select From Manufacturer s Designs for both the right and left eyes Selecting the Auto Fill OU button will fill in the default manufacturer or stock lens information designated in your protocol However selection can be made independently by simply selecting a lens name diameter lens material and color choice Selections for the right eye can be automatically transferred to the left eye by clicking on the OD OS button Clicking on the More Lens Detail button will provide information concerning the lens you have selected as well as manufacturer information Clicking on the individual folder tabs Lens Info Manufacturer Info Additional Info Custom Info displays files specific to each lens material or design Proceed to the simulated fluorescein display by clicking on the Fluorescein Display button Note The software will select the appropriate base curve based on the sagittal depth specified in your fitting protocol and the lens diameter selected It does not use the manufacturers own fitting methods or nomograms to design a lens Simulated fluorescein patterns and tear depth graphs are displayed for both eyes simultaneously A grid representing 1 square millimeter divisions overlay the simulated fluorescein pattern The scale to the left of each pattern corresponds to the amount of fluorescein in microns simulated for the contact lens as it would appear on the cornea
35. ses For lenses that ride high a prism ballast lens may be used to help position the lens properly If the lens rides low on the cornea it may be necessary to use a lenticular design to lift the lens In some cases just going to a slightly larger diameter or steeper base curve will be sufficient to stabilize if not center the lens Several rigid contact lens manufacturers make lenses with a periphery that is steeper than the base curve These lenses were first developed for clinicians who were attempting to fit patients using orthokeratology This type of lens has a flatter base curve to fit the flatter central cornea and steeper periphery to fit the steeper transitional zone of the cornea Aspheric lenses have been used in some refractive surgery cases however these lenses work best when the central cornea is steeper than the transitional and peripheral zone of the cornea The beauty of videokeratography in working with refractive surgery patients is that the clinician can easily visualize the corneal topography which is a wonderful aid to help the clinician select the right contact lens for these patients Post Keratoplasty Some clinicians prefer to wait until the patient is one year to eighteen months post op and or after sutures have been removed before the fitting of contact lenses are initiated on a cornea transplant Others fit lenses within one to two months with all sutures intact Most clinicians initiate fitting around four to six
36. the Continue button on the bottom of the screen On the RGP Selection screen see Figure 6 click next to Design a Custom Lens Based on Protocol for both the right and left eyes Protocol information is noted at the bottom of the screen in an information box Selecting the Auto Fill OU button will fill in the default manufacturer or stock lens 8 information designated in your protocol However selection can be made independently by simply selecting a diameter lens material and color choice Information chosen for the right eye may be copied directly to the left eye by clicking on the OD OS button Clicking on the More Lens Detail button will provide information concerning the material selected as well as manufacturer information Clicking on the individual folder tabs Lens Info Manufacturer Info Additional Info Custom Info displays files specific to each lens material or design Now click on the Fluorescein Display button Simulated fluorescein patterns and tear depth graphs are displayed for both eyes simultaneously A grid representing 1 square millimeter divisions overlay the simulated fluorescein pattern The scale to the left of each pattern Figure 6 corresponds to the amount of fluorescein in microns simulated for the contact lens as it would appear on the cornea The default values for the Absolute view of the fluorescein scale are from zero to 75 microns and have been determined to be the most re
37. the use of lenses and waiting for the cornea to become stable It requires the clinician to obtain keratometry measurements from a time when the patient had been without their lenses for a minimum of one to two months This information may be obtained from the patient s original contact lens fitter or from a subsequent fitter As long as the patient has been out of lenses for an extended time the K readings can be considered relatively reliable Once the clinician has the original K readings videokeratoscopic images should be obtained If the patient s original K readings differ from the videokeratograph K s the base curve of the lens to be fit is calculated using the original K data This base curve is then substituted in the Simulated Fluorescein Display screen The simulated fluorescein pattern and sagittal vaulting effect over the patient s current topography are then evaluated If the lens parameters produce a reasonable fluorescein pattern and vaulting effect this lens should be ordered If the parameters produce a poor vaulting effect the base curve and or diameter and peripheral curve system can be altered on the Simulated Fluorescein Display screen until the desired vaulting effect is achieved If the wearing of contact lenses has caused the K s to flatten significantly and lenses are reordered based on the original K s the clinician may find that the Simulated Fluorescein Display will show a tremendous increase in the sagittal values Howeve
38. ting a lens suggested by the software evaluate the actual fluorescein pattern of the lens on the patient Adjust the brightness and contrast level of your computer monitor to match more closely the appearance of the actual fluorescein pattern to that of the simulated fluorescein display This will ensure that the brightness of the display will match the actual brightness for subsequent exams provided that no additional adjustment is made to the monitor brightness level When trial lenses are recommended The presence of irregular astigmatism may cause RGP power calculations to be somewhat inac curate Sphero cylindrical refractions obtained for these patients usually do not accurately reflect the best corrected visual acuity Best corrected visual acuity is be obtained by fitting an RGP lens then performing an over refraction Therefore we strongly recommend the use of trial lenses and overrefractions to calculate final parameters for these patients Saving the contact lens fitting information Contact lens fitting information is not saved in this version 4 0 We suggest printing the order form and making note of the refraction and eye images used Saving and accessing patient history and contact lens information will be available in a future version How to set up a fitting protocol The basis of this software program is such that all clinicians may customize their own fitting preferences or protocol defaults to use throughout the progra
39. urve of 56 00 diopters is tried on the patient Again the design of the lens and the diameter will depend on the location of the cone and its relative size As with the previously mentioned method the optical zone and diameter of the diagnostic lens should be sufficient to satisfy the patient s optical needs Either one of these methods should provide the clinician with adequate information to determine the best starting point for diagnostic lens evaluation The initial diagnostic lens will determine whether the clinician needs to go steeper flatter smaller or larger Using these methods can decrease the amount of time spent trying different diagnostic lenses and should produce more successful fits The choice of using one type of lens design over another is up to the clinician and what they are comfortable with In general aspheric and Bi aspheric cone designs work best with small central cones that are located close to the midline of the cornea whereas the Soper Cone lens works well for almost all cones Piggy Back Fitting System On advanced and difficult to fit cones it may be necessary to fit the patient in a piggyback system Although this type of fitting is more cumbersome and requires greater patient compliance the rewards can be great in the form of relieving the stress over the cone reducing the risk of corneal abrasions and increasing the visual acuity for many of these patients A soft lens with a high DK value is first fit on the pati
40. ver refraction The original suggested power can be accessed by clicking on the Suggested Power button The Trial Fit function can be activated for soft toric lens fitting see Figure 11 Click on the Trial Fit button and enter the amount and orientation of rotation that is present with the trial lens you are fitting on the patient The software will automatically recalculate the axis necessary to fit the patient Computations based upon trial lens fitting will be highlighted in red You must then re select the appropriate axis in the axis field box To clear all fields once a selection has been made click on the Reset Lens Parameters button Extensive information regarding the selected lenses can be accessed by clicking on the Show More Lens Detail button see Figure 12 Lens material name water content oxygen permeability and recommended disinfecting systems can be displayed by clicking on the Lens Info Folder tab at the top of the screen Manufacturers address telephone numbers and customer service lines can also be referenced by clicking on the Manufacturer Info Folder tab Most toric lenses U S version only have the manufacturer s fitting guide scanned into the database for quick and easy reference The Additional Info Folder provides lens care recommendations as well as noting the life expectancy of the material selected Custom Info Displays availability of custom design parameters and all color choices f
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