Using Orthotool Software

Using Orthotool Software

OrthoTool 101010 (2008) Original Design with 5 Curves. You can just use the new version 2013 Toric RC, AC & PC only with OT 2008 so far Hyperopic ortho-k GP lens design Aspheric multifocal design For empirical designs

Select Lens Design Toric FC/AC/PC Type in 1.0, 1.25 etc 1. Fill in patient s name & reference 2. Fill in Rx: K readings, refraction, e value (if available) 3. Choose lens design (for simplicity, use CC Chow 1-10.8mm or smaller & CC Chow 2 11mm & above)--- go to preference page for that 4. Clear right/displace right, clear left/displace left 5. Go to Preference page

Click the button and you ll have different choices Most commonly used: Chow 1, Chow 2, Aspheric multifocal

Choose the DESIGN you want (CC Chow 1 ) If you get lost, click Top of Form at right hand corner, and it will lead you to the preference page again * Use Asphere 75 9.8 for hyperopia ortho-k & multifocal

Understanding Control Clearance Philosophy RED LINE = Pre determined values

(1) (2) (1) This is pre determined. Only adjust Apical clearance from 0.05 to 0.08 (5 to 8 microns) Use 0.09 for higher targeting (2) Choose your desired diameter/width a. diameter largest possible/>90% of HVID b. RC width: low target smaller--- plano to -3D width of 0.4mm (this is the general rule, you can adjust accordingly depending on the results) -3.5 to 5D width 0.5mm -5 to -7D width 0.7mm, above use 8.0mm You need more room for high target, narrower the width, higher the force

You can make your own choice. 2 nd & 3 rd curve=ac1 & AC2 Adjust AC1 & AC2 to come up with desired OZ diameter OZ as small as possible for myopia control purpose Go to Preference Page again:

Adjust E value of cornea to match AC from trial lens. Adjust the e value number at column 8, (2 nd curve=ac1) Click here to choose lens designs. For the time being, just use CC1 or CC2 and aspheric 75/9.8 for multifocal & hyperopia designs Press steeper or flatter for desired targeting power

Most of time the width should be 0.6 (mideum range). For extreme high targeting, use 0.80. If radius of Reverse Curve (RC) gets too steep (e.g. below 6.0mm (56.25), it s difficult for the lab to manufacture. Widen RC width. For low powers, you can use width of 0.5mm or even 0.4 mm

Choose the proper AC curves If you have a set of trial lenses (10.8 mm from Dr. Chow s recommendation), based on the corneal e value, you can choose one that is close enough to find out if the fit is acceptable (360 degree rather heavy touch still with ample movement). Use your two fingers as instructed at the lecture instead of slit-lamp. The new set of trial lens with 12 lenses is sufficient for targeting power from plano to -8D (see next page) If you don t have trial lens, just use flat K to start, or go 1/2D flatter Since most of the e values are not reliable, once I found out the proper ACs from the trial lens, I usually adjust the e value to match the number. Now there is only one trial set (12 lenses) targeting @ -4D with RC width of 0.6mm If you want to use the same trial set for higher targeting (>-8D), change your width @ Preference Page to 0.7mm or even 0.8mm Later on, you can ask me to design an aspheric trial set

Treatment Zone (OZ) & Pupil Size Determine the pupil diameter in room illumination Go as small as possible for myopia control purpose. The smaller the treatment zone, the better the myopia control effect The most commonly used BOZD=5.4 mm

Toric FC,AC & PC For high astigmatism (limbal to limbal), displaced corneal apex, extremely low shape factor (low corneal e value), extremely flat corneas, or an extremely large HVID, use toric design Choose from 1.0, 1.25, 1.50 or higher if necessary NOTE: if you are using the new upgrade (Chow 5.1 & 5.2), toric design may not be necessary. Just find a trial lens with AC showing good alignment (360 degree dark circle while the lens is stable). Ignore the central bearing in the beginning and adjust RC width/tlt later for optimum result. With the use of apsheric 6-curve design, toric curve(s) are not necessary

Lens Diameter First determine the corneal HVID Choose diameter approx 0.4 mm smaller than HVID to avoid tight fit (e.g. HVID 11.4mm, use 11.0mm lens diameter, HVID 11.0mm use 10.6mm) If you have to use a tighter AC, reduce OAD by 0.2mm and use PC width of 0.3mm and apply a steeper PC radius (don t usually go below 10D) Total diameter of lens is dependent on lens fit. Normally you want to cover as much corneal surface as possible in order to have enough room for all curves Or just go to largest possible. Use slip-lamp to determine the final size. As long as the lens is still within the HVID Extreme large lens may cause tight fit. Based on the Controlled Clearance theory of OrthoTool, balance and sufficient TLT under lens is vital

A. Central Optical Zone B. Fitting Zone C. Facilitation/Relieve/Enh ancement Zone D. Alignment Zone(S) E. Periphery Zone Double Reverse Curves: Most powerful for successful Ortho-K practice Edward Chow, OD

OrthoTool Tear Film Analysis Chart Controlled Clearance Diagram Shows the Exact Amount of Tear Volume under Lens 3 8 1 2 4 5 6 7 9 Front Optical Zone, Anterior Bowl The tear film analysis chart shows us the voided area (space) between the lens and the corneal model If the model is off, then the entire lens and tear film is off

OrthoTool Tear Film Analysis Chart (Cross-Section of Lens) Total Diameter=10.6 mm, BOZ Diameter=5.40 mm RZ=1.60 mm (0.8) PC=0.6 mm (0.3) BOZ=5.40 mm AC=3.0 mm (1.5) 5.40 mm 10.6 mm There is a designated area/volume in each zone for different target and condition

Force Concept Represents True Tear Volume & Force Applied at Various Points of Interest 5 Curves 6+ Curves Surface Tension Surface Tension Force Negative Force: Pull Positive Force: Push Small Capillary Force

Forces Concept (Depending on corneal rigidity, sometimes works well) Imbalanced Excessive Fluid Force Balanced Fluid Force

Forces Concept Low Target At time, harder to mold low Rx due to insufficient force applied Increased Force Showing Balanced Force Tear film distributed unequally, pressure is created Depth of tear film in each zone is critical

Facilitation/Relieve/Enhancement Curve Functions: To create tear film equilibrium To create extra pressure for the steepening of the midperipheral corneal tissue (sucking tissues from AC, the capillary force) To align/bridge FC1 & AC1 (both may be too tight/or force too strong) Form a smooth transition between these 2 curves, especially if aspheric BOZ is applied Help to re-fit old or new patients currently on reverse geometry or GP lenses who are not responding to treatment Difficult corneas that are not responding to treatment (enough targeting but not responding) Enhancement for higher targeting When all other designs failed Enhancement of fit so patients can stay out of lenses for a couple of days

Designing Your Own Trial Lenses The first curve(s) to be determined is the Alignment Curve(s) Set the targeting power Use the preference sheet to set the desired parameters tear clearance & width Change the corneal e value to come up with the desired Alignment Curve(s): Desired AC s: 8.54, 8.44, 8.33, 8.23, 8.13, 8.04, 7.94, 7.84, 7.75, 7.67, 7.58 & 7.50 The software will calculate for you the correct FC (RC)

New Software Orthotool 2013

Design Format/Preference Void area (value 0.00) Pre-determined, DO NOT CHANGE Standard values

Comparing Original Software & Orthotool 2013 Aspheric BOZ Go extra steeper for RC, use with care!

Spherical vs Aspheric Design Tear Volume Tear Volume

Tear Film Diagram Reverse Curve is split into TWO (FC 2 is flatter than FC 1) 29 Tight Fit FC2 AC starts here Edward Chow, OD

Desired TLT Diagram (Chow 5.1) Relieve Curve

If you find the lens is still too tight, change FC2 TLT Make sure they match 1. Maintain width @ 0.3 all the time, change TLT (1a) from 0.05 to 0.07 (0.06 mostly used) 2. Apex TLT from 0.005 to 0.008mm depending on target (5 to 8 microns)

Simple Approach to start the program Standards: pre-determined A. Base Curve (usually target extra: 2.0D or more) B. Diameter C. Centre thickness: 0.24mm D. Edge thickness: 0.14mm E. Anterior Bowl (front optical zone diameter): 6.0-7.0 mm. Use 7.0 mm to tighten fit. Control lenticular flange thickness

Variables: change according to different situations A. E values: best to find out with trial lenses of known AC B. RC widths: depending on amount of targeting, usually with wider width for higher targeting (e.g. 0.4, 0.5, 0.7, 0.8mm) -3D or less=0.4 mm, -3.50 to -5D=5.0 mm, -5.50 to -7D=6.0 mm, >-7.50 D=7.0 or 8.0 mm, etc. Most common use is 0.5 mm. Adjust accordingly with FC2 if encountered tight fit. For more aggressive results, use a narrower width. Usually use a smaller width for more effective result C. AC radius: based on the e value & trial fit. Software will calculate the best RC radius D. BOZD: determine the desired diameter and adjust ACs & PC width to accommodate

Design Format/Preference 1a curve width always set at 0.3, 1a TLT set at 0.05 and can go up & down depending on the fit. Change of this TLT also make changes for AC1 (which is adjacent to the 1a curve. RC TLT can go up & down to adjust SAG

Type your name & address Chow 5.1 & 5.2 with additional curve (1a curve & width 1. Chow 1 & 2 are the old version 2. Chow 5.1 & 5.2 are new version. 3. Use aspheric trial set for aspheric design in both version

Using spherical trial sets (if using aspheric trial set, go directly to Chow 5.1 & 2 design) 1. Once the values @ Chow 2 are set, it can be used as a design format/model to be adjusted by Chow 5.1 2. For some corneal shape, you may want to fit a tighter AC. You have to adjust 1a TLT & width to accommodate the changes

Now matched by increasing RC TLT to 0.025 If you want to have an extra force, set at 0.02, and you can go less

Variables: 1. OZ: adjust diameter/rc/ac/pc width to come up with desired OZ diameter 2. RC: adjust width with amount of targeting (e.g. <-4D use 0.5mm, -4.5D to -6D use 0.6mm, >-6D to -8D use 0.7mm, etc.) 3. BC eccentricity=boz asphericity: small OZD you can use higher e value (5mm=1.4, 1.5 or more), larger OZD use lower e values (5.4=1.4, 5.6mm=1.3, 5.8mm=1.2, 6mm=1.0) 4. Target power: minimum 2D and you can go as high as 3.5D or more. Over-refract to determine how much more to target 5. Most used value for 1a width is 0.3mm (serves the purpose of sucking more tissue from AC1 & balance off FC1 & AC1) 6. These 2 values (AC1 & 2) can be interchanged 7. Edge curve width=pc: most of time at 0.3 mm 8. Edge clearance (4 th curve radius): use the value as close to the TLT provided at Design Page (just round off to the highest value and not lower than 10D. Usually 11.0 or up to 12.0

1&2 OrthoTool Tear Film Analysis Chart Controlled Clearance (6-Curves Design) Diagram Showing Tear Layer Thickness (TLT) at Various Sites 9 Front OZ Diameter (AB) 1 2 3 4 5 6 7 8 Lens should be constructed in a way that is close to the desired end result, but with a small additional flattening beyond the exact result desired (the new Jessen Rule) 1. Apex with TLT from 5 microns to >8 microns 2. Increase in TLT (RZ) with application of aspheric Back Optical Zone

Spherical VS Aspherical Base Curve Flatten Faster

Aspheric BOZ As Function Of Treatment Zone BC Radius Flatten Faster Towards Edge Of BOZ OZD=5.2 mm OZD=6.0 mm

OrthoTool Tear Film Analysis Chart Total Diameter=10.6 mm, BOZ Diameter=5.40 mm 3 & 4 RZ=1.60 mm 0.5/0.3 mm PC=0.6 mm (0.3) BOZ=5.40 mm 10.6 mm 0.3 mm AC=3.0 mm (0.9-0.6 mm) 5.4 mm Most powerful area in forces. Success depends on the force in this area for myopia control. Changes in forces determine the position of lens location (trouble shooting for displacement such as lateral, low and high riding)

Comparing RC1 & RC2 Different between 0.2 vs 0.3 mm 6.21/7.23 vs 6.21/7.50

OrthoTool Tear Film Analysis Chart Total Diameter=10.6 mm, BOZ Diameter=5.40 mm 5,6 &7 AZ=3.0 mm PC=0.6 mm (0.3) (Average 30% of total diameter) (0.9-0.6 mm) 10.6 mm Requires minimum TLT in this area (for centration) AZ=1.50 mm

Alignment Curves 1 2 3 1 st curve(s) to be determined Provides lens movement & assist centration Provides surface tension force that will help to build up tissue at the Reverse Zone

Hyperopic Ortho-K The forces are OPPOSITE to myopic OK Myopic: compression centrally, tension peripherally. Hyperopic: Tension centrally, compression peripherally.

Topographical changes driven by mid-peripheral compression At 5.0 mm

Plano = 20 microns of Apical Clearance +1.00 = 20 + 10 = approx. 30 microns +2.00 = 20 + 20 = approx. 40 microns +3.00 = 20 + 30 = approx. 50 microns +4.00 = 20 + 40 = approx. 60 microns

Eccentricity Required to Accomplish the Desired Apical Clearance +1.00 D correction use an eccentricity of 1.60 +2.00 D correction use an eccentricity of 1.70 +3.00 D correction use an eccentricity of 1.80 +4.00 D correction use an eccentricity of 1.90 +2.00 D. correction eccentricity of 1.75 40 microns +4.00 D. correction eccentricity of 2.00 60 microns

+2.00 D. Correction +4.00 D. Correction

+2.00 D. Correction +4.00 D. Correction

Hyperopia Orthokeratology Tension & Compression Tension Compression

RC is going to be a radius between 7.20 to 7.50 (width 0.5mm) Radius of RC needs to be adjusted flatter and flatter until the first radius that lifts the lens in the periphery AC approximately 1.0D flatter than flattest K (width 0.8mm) PC should provide 110 to 120 microns of clearance

Reminder: 1. BOZ should be as small as possible 2. RC width (Chow 5.1): from 0.4 to 0.8mm. Rarely goes to 1.0 mm unless it s for very high targeting (>-10.0 D) 3. RC radius (TLT): starting from 0.02 or 20 microns (and lower to 0.015 to increase force at RC. Or increase to 0.022 or higher for more relieve) 4. 1a (relieve/enhancement curve, Chow 5.1) width: usually 0.3mm. If necessary, you can go to 0.4mm (for extreme tight AC, e.g. toric cornea, or lateral decentration) 5. 1a clearance (TLT): usually sets at 0.006 or 6 microns. Rarely you have to go to 0.08 or above. Go to 0.005 for reduced TLT or 0.007 to increase TLT 6. In some cases that you have to fit a tighter AC, reduce OAD by 0.2mm & change PC width to 0.3mm & steeper PC radius

8. Learning to read the topographer maps: a. insufficient central bearing: flatten RC radius b. insufficient RED zone: extra targeting, increase BOZ asphericity (adjust BOZ diameter to a smaller value), reduce RC zone width (smaller width creating more force) or adjust all features. c. AC width: please understand that the total width of AC comprises a small percentage of the OAD (normally <2mm, usually 1.5mm). You can go as steep as possible especially with the relieve curve bridging FC1 & AC1 d. Displacement (lateral): only need to adjust the 1a curve with AC the same e. Superior displacement: AC too loose or not enough force at RC f. Inferior displacement: AC too tight. Loosen AC & Steepen RC

Preferred Labs In U.S. and Canada (This is important since the lens designs are complicate. I have tested out the quality of lenses manufactured over a period of 3 years. OrthoTool users have a lower fee per lens than normal fee in the market) 1. GP Specials (Att. Mark: 800 889-0379) 2. Precision Optics (Vancouver) Att. Randy They provide lower fee per lens compared to other labs with one free exchange within 120 days.