An Introduction to Orthokeratology Part 1 Cary M Herzberg O.D., FIAO President, American Academy of Orthokeratology and Myopia Control Las Vegas NV 2014 How Does Ortho-K Work? Financial Disclosure The content of this COPE Accredited CE activity was prepared independently by Cary M Herzberg, OD, FIAO without input from members of the ophthalmic community. Dr. Herzberg has no direct financial or proprietary interest in any companies, products or services mentioned in this presentation. The content and format of this course is presented without commercial bias and does not claim superiority of any commercial product or service. Pull Squeeze Film Force When the pre-corneal tear film is distributed unequally across the corneal surface i.e. thinner in the center, thicker in the periphery, a pressure is created as the fluid tries to find equilibrium. (Negative Pressure Force) 7.15 47.25 10 microns x Positive Push Force Negative Pull Force This pressure is a positive (push force) in the center of the cornea and a negative (pull force). BC: 38.00 D. (8.90 mm) Dia: 10.5 OZ: 6.0 35 microns 55 microns Steep Reverse Curve .575 microns RZD .600 Steep RC 55 microns 1 Push Function of the Zones/Curves (Positive Pressure Force) x BC: 38.00 D. (8.90 mm) Dia: 10.5 OZ: 8.4 Clearance Touch Treatment Curve • • • • AKA base curve Applies positive pressure to tear film Causes epi cells to migrate towards periphery Creates a decreased saggital height Alignment Curve • • • • • AKA fitting curve Flatter than RC Keeps lens centered If lens ride high or excessive mvmt, steepen If lens rides low or too tight, flatten Reverse Curve • • • • Secondary curve Tear reservoir surrounding Tx zone Induces negative pressure (pull) Receives migrating cells resulting in increased corneal thickeness Peripheral Curve • Tear circulation • Edge lift • Ease of removal 2 3 Curve Lenses • Base Curve • Reverse Curve • Alignment Curve‐counterformal 5 Curve Lenses • Base curve, RC, PC • Multiple Alignment curves‐conformal • AC1 steeper than AC2 4 Curve Lenses • Optic zone, RC, Edge lift • Alignment curve‐conformal • Designed to match peripheral cornea for a better seal. Standard Myopic Orthokeratology Compliments of Charl Laas and Chris Eksteen Hyperopic Orthokeratology • The FDA has approved Ortho‐K for the treatment of myopia up to ‐6D • Accuracy and repeatability high allowing for advanced computer programs with data collected over thousands of fits to design for best results. • Early results from the SMART study indicated a first fit success rate of 80.5%. • Also there was a 95% success rate with a second fit(Eiden,et al,2009 3 TORIC ORTHOKERATOLOGY Incomplete/Apical Limbus-to-Limbus Design Choices For The Toric Cornea Toric Alignment Zone • Toric Alignment Zone Design – Contours peripheral cornea – Reduces inferior lift-off on w-t-r corneas Double Toric Designs • Toric reverse and alignment zones – Contours entire cornea – Utilizes different design for each meridian 4 Fitting The Presbyopic Patient • Monovision • Progressive Designs Center Distance(CD) Center Near(CN) PRESBYOPIC ORTHO‐K Rx: ‐5.75 ‐2.00 x 180 TOPOGRAPHY IS THE STANDARD OF CARE All Topography Maps Are Not = Difference Map Just About Everything Refractive Map Treatment zone size, Rx Topography Maps Which One Is The Best For Corneal Reshaping Evaluation? 5 All Topography Maps Are Not = Axial Map Treatment zone size,Rx Tangential Lens position during sleep TROUBLESHOOTING THE ORTHOK LENS Fitting Rules for Reverse Geometry Lenses  Steepening reverse curve(RC) by .15mm(.75D) increases lens sag and apical clearance by 10 microns  Flattening the RC by .15mm decreases lens sag by 10 microns Common Complications  Position/Movement  Lateral Rider  Low Rider  High Rider  Refractive  Steepening the alignment curve by .05 mm(.25D) increase apical clearance by 5 microns  Flattening the AC by .05mm decreases the apical clearance by 5 micron.  Central distortion  Not enough effect  Health  Central Staining  Infection Low Riding Lenses Position Frowney Face Map 6 Low Riding Lenses  Not a significant problem unless lens adheres or patient experiences ghosts  Because peripheral cornea is flatter than central cornea the lens may exhibit heavy touch in the superior quadrant of the alignment zone Low Rider‐Symptoms     Decreased Acuity Monocular Diplopia Morning Lens Adhesion No Symptoms  Solution: Flatten the alignment curve by .10mm. It will be necessary to change the RC to maintain desired relationship. Low Rider‐Cause  Cylinder  Tight Lens High Riding Lenses Low Rider‐Cure  Toric Design  Loosen AC  Loosen FC High Riding Lenses • Insert a smiley face  Careful attention to NaFl pattern will tell source of problem  Often alignment zone is not parallel to cornea in superior quadrant. Allows lens to move up without resistance.  Solution: Steepen the alignment curve by .10mm and make appropriate change in RC.  If NaFl looks perfect  increase CT while decreasing edge thickness  utilize prism to pull the lens down‐rare Smiley Face Map 7 Lateral Decentration Lateral Rider‐Symptoms       Decreased acuity Increased acuity Lateral monocular diplopia Decreased holding time Discomfort No symptoms Lateral Decentration (Nasal and Temporal) Lateral Rider‐Cause  Most difficult problem to solve  Corneal cylinder  Asymmetry of cornea  Tight lids  Observe NaFl in nasal and temporal quadrant  Too much pressure at RC nasally will push the lens temporal  Too much pressure at RC temporally will push lens nasal  Solution:  Increase lens diameter by adding additional alignment curve and decreasing Width of RC Adherence Adherence • Risk factors – – – – – – Light lids Minimal toricity Decreased corneal rigidity Thin cornea Is patient dependent Flat lens ‐ Fennestration doesn’t help 8 Refractive Refractive Problems  Central Distortions  Corneal distortion  Residual cylinder  Central islands  Small areas of distortion at or near visual axis resulting in poor acuity and/or ghosts  Not enough effect  Need more myopia reduction  Effect fading over time Central Islands  If poor centration, Make changes to achieve centration  Lateral decentration  High rider  Low rider  If lens centers and moves properly  If lens centers and moves properly  Decrease the sagittal depth by modification of design between AC and PC  If this does not solve problem flatten BC and modify RC to maintain alignment Central Distortion Central Distortion ‐ Symptoms     Decreased vision Irritation after lens removal Vision clears after a few hours Does not occur every day Central Distortion ‐ Cause  Lens adhesion in morning  Not using rewetting drops before insertion  Coated lens 9 Central Distortion ‐ Cure     Refractive Problems Lens Deposit Formation Inspect lens for deposits Review insertion techniques Change rewetting drops Steepen Base Curve Deposit Formation Refractive Problems Residual Cylinder • Will cause poor or unstable treatment • Review care techniques • Switch to H2O2 Residual Cylinder ‐ Cure  Toric Design  Flatten Reverse Curve Vision‐ related problems Under Responders  Some respond slower or to a lesser degree  Rigidity of Cornea  Dry Eye  If NaFl looks perfect  Time is in your favor: Revaluate patient in 2‐3 weeks.  If NaFl pattern shows insufficient apical touch  Flatten the BC by .50 to .75 D  Verify patient is compliant with your instructions  Some patients do not change as much as we anticipate 10 Vision‐related problems Poor retention (VA does not hold all day) Consider the amount of change the cornea has undergone Observe the centering characteristics Vision‐related problems Ghosting at night  Lens is decentered  Central Island  Large pupils If there is not sufficient applanation of the cornea, flatten the BC Vision‐Related Problems Health Issues – Central Staining Lens Imprint on Cornea Lens is decentered AC is too tight Dirty lens Health Issues – Central Staining Central Corneal Staining  Due to either  Potential for infections  Treat aggressively  If can not resolve, take patient out of lenses. Mechanical irritation  Inside surface of the lens dirty  BC too flat  If all of the above in order switch to a higher Dk  Corneal physiology Basement cell membrane defects Dry Eye 11 Health Issues – Iron Lines Health Issues – Iron Lines  Common  No associated health issues  Transitory Health Issues Fischer‐Schweitzer Polygonal Mosaic • Rarely seen following orthoK wear • Disappears within 10 min after removal • Of no clinical significance Courtesy of Orthokeratology Principles and Practice (Mountford, Ruston, Dave) MICROBIAL KERATITIS  1 in 2500 daily contact lens wears and 1 in 500 overnight wearers in the USA develop bacterial keratitis each year 12  The introduction of disposable lenses did not reduce the risk of infection  Poggio et al (1999)/incidence of bacterial keratitis rose with extended wear soft use to 20.9 per 10,000  Risk of infectious keratitis in disposable lens wearers was increased relative to daily wear soft or gas‐permeable lenses.  Ren et al (2002) Silicone hydrogels and hyper DK RGPs showed reduced pseudomonas binding  The primary risk factor for developing contact lens– related bacterial keratitis is sleeping with the lenses in. Cary Herzberg, O.D., FOAA, FIAO • Corneal Reshaping Lenses have no more risk than extended wear SCLs • (Bullimore)  Thirty years of practice  Leadership in the field of contact lenses      Advisory board GPLI Consultant to the contact lens industry Co‐inventor of the macrolens elite Co‐inventor of the macrolens “OK” lens Design consultant C&H contact lens  Leadership in the Optometric community  President Orthokeratology Academy Of America  Board member Orthokeratology Academy of America  Fellow of the Orthokeratology Academy of America  Fellow of the International Academy of Orthokeratology  Advisory Board member for PRIO Corporation  Children’s Advisory board president PRIO Corporation American Academy of Orthokeratology and Myopia Control and the International Academy of Orthokeratology Benefits of Membership • Mentor program for new fitters • International Google forum to discuss orthoK‐related issues and problems • Largest corneal reshaping annual meeting • Cutting edge information related to orthoK • www.orthokacademy.com 13 Thanks!  E‐mail:  [email protected]  Office:  2853 E. New York Ave.  Aurora,Il 60502  Phone:  630‐851‐3338  Fax:  630‐851‐2740 14